MIKES METROLOGY Calibration Services · Calibration of direct voltage and current ... High voltage and high current..... 36 Acousic ct alibrations

MIKES METROLOGY

Calibration ServicesInternational competitiveness

and reliability

2 — VTT MIKES METROLOGY Calibration services

Copyright © VTT MIKES 2018

VTT Technical Research Centre of Finland LtdP.O. Box 1000 (Vuorimiehentie 3, Espoo), FI-02044 VTTTel. +358 20 722 111, fax +358 722 7001www.vttresearch.com

http://www.vttresearch.com/

VTT MIKES METROLOGY Calibration services 2018 — 3

VTT MIKES Metrology

Mass, pressure, flowCalibration of weights ........................................................................... 6Calibration of pressure measuring devices ............................................ 8Calibration of force and torque ........................................................... 10Water flow meter calibrations ............................................................. 12Calibration of gas flows and density of liquids ...................................... 14Acceleration of free fall ....................................................................... 16

Humidity, temperatureCalibration of hygrometers ................................................................. 18Calibration of radiation thermometers .................................................. 20Fixed point calibration of platinum resistance thermometers ................. 22

Electricity, acousticsCalibration of direct voltage and current............................................... 24Calibration of alternating voltage and current ....................................... 26Calibration of capacitance and inductance standards ........................... 28Calibration of resistance ..................................................................... 30Calibration of power and energy at line frequency ................................ 32RF- and microwave calibrations ........................................................... 34High voltage and high current............................................................. 36Acoustic calibrations............................................................................ 38

TimeCalibration of time, time interval and frequency .................................... 40

OpticsOptical quantities ................................................................................ 42

Length, geometryQuantitative Microscopy – Atomic Force Microscope ........................... 44Characterization of nanoparticles ....................................................... 46Calibration of laser interferometers ..................................................... 48Interferometric calibration of gauge blocks ........................................... 50Calibration of gauge blocks by mechanical comparison........................ 522D and 3D measurement of form and surface roughness ..................... 54Optical measurement of surface microstructures ................................. 56Calibration of tachymeters ................................................................. 58Angle and perpendicularity measurements .......................................... 60Measurements of accurate inner and outer dimensions........................ 62Coordinate measurement.................................................................... 64Optical coordinate measuring – vision measuring ................................ 66Calibration of line scales and distance meters ..................................... 68Interferometric measurement of flatness and form ............................... 70Machine tool measurements .............................................................. 72Measurement of roundness................................................................ 74Calibration of microscopes and calibration standards............................ 76Length in geodesy .............................................................................. 78

ChemistryWater quality ...................................................................................... 80

4 — VTT MIKES METROLOGY Calibration services 2018

VTT MIKES MetrologyVTT MIKESTekniikantie 1FI-02150 ESPOO

VTT MIKES-Kajaani, Tehdaskatu 15,Puristamo 9P19FI-87100 KAJAANI

Tel. +358 20 722 111 (call centre)Email: [email protected]

Finland has a slightly distributed metrology infrastructure. MIKES is the National Metrology Institute andit acts as the National Standards Laboratory for most of the quantities. MIKES designates the other Na-tional Standards Laboratories and Contract Laboratories.

MIKES is a specialised research institute for measurementscience and technology. As the National Metrology Instituteof Finland, MIKES is responsible for the implementationand development of the national measurement standardssystem and realisation of the SI units in Finland.

The number of staff is 65 supported by VTT ltd. administra-tion.

The MIKES building is situated in the city of Espoo and itsbranch office in Kajaani is the northernmost National Stand-ards Laboratory in the world. The high-quality laboratoriesprovide the most accurate measurements and calibrations– close to 1600 certificates per year – in Finland.

MIKES also performs high-level metrological research anddevelops measuring applications in partnership with indus-try. The activities of MIKES aim to improve industrial com-petitiveness, the national innovative environment, and pub-lic safety.

MIKES is a signatory to CIPM MRA (International Commit-tee for Weights and Measures, Mutual Recognition Ar-rangement) and a member of EURAMET (European Asso-ciation of National Metrology Institutes). Through interna-tional collaboration, MIKES is linked to the internationalmeasurement system and to the European and interna-tional metrology research community. MIKES takes activelypart in the European Metrology Research Programme(EMRP and EMPIR).

• We realize SI-system of units in Finland

• We do high level research in the field ofmetrology

• We develop measurement methods forindustry and society

• We offer high level calibration service,expert service and training

http://www.mikes.fi/


The Metre Convention

The National Measurement Standards System

Figure 1. National measurement standards system in Finland. Aalto = MIKES Aalto Metrology Institute, SYKE = FinnishEnvironment Institute, FMI = Finnish Meteorological Institute, STUK = Radiation and Nuclear Safety Authority, NLS =National Land Survey of Finland, and FGI = Finnish Geospatial Research Institute.

Calibration and Measurement Capa-bilities (CMCs) recorded in the BIPMkeycomparison database, KCDB

Acoustics: 30Length: 59Time and frequency: 11Thermometry: 44Optics: 53Mass and related quantities: 28Electricity: 99Ionising radiation: 30Chemistry: 5

Total Finland 359 / total 24031 entriesSource :BIPM July 1, 2015, kcdb.bipm.org

Voluntary peer review project

MIKES is a coordinator in the EURAMET TC-Q pro-ject Peer reviews of Quality Management Systems(QMSs). The other partners in the project are CMI(CZ), GUM (PL) and SMU (SK). The project supportsthe evaluation and improvement of QMS processesand procedures of the participating institutes. Learn-ing from each other and sharing the best practice forQMS implementation are other goals of the project.The QMSs of the institutes are based on ISO/IEC17025. A programme with on-site visits by peers isplanned on an annual basis and one or two fields ineach institute are reviewed every year. In 2012, theQMS of MIKES in the field of length metrology waspeer reviewed by an expert from GUM, and viceversa. In addition, the humidity laboratory of MIKESwas peer reviewed by a GUM expert.

Figure 2. CIPM MRAlogo tells us, that ourmeasurement resultsare accepted globally.

Electricity, acoustics, time, frequency, length, tempera-ture, humidity, pressure, mass, force, torque and flow

Water quality Air quality Ionising radiationLength in geodesy andacceleration of free fall

Photometry andradiometry


Mass, pressureand flow

Temperatureand humidity

Electricity, timeand acoustics

Optics Length andgeometry

Chemistry

Calibration of weightsHeikki Kajastie, ResearcherTel. +358 50 410 5511(Espoo)[email protected]

Kari Kyllönen, Research TechnicianTel. +358 50 4434180 (Kajaani)[email protected]

MIKES, Tekniikantie 1, FI-02150 EspooMIKES-Kajaani, Tehdaskatu 15,Puristamo 9P19, FI-87100 KajaaniTel. +358 20 722 111, www.mikes.fi

TraceabilityThe weight standards of MIKES mass laboratory aretraceable via the Pt-Ir prototype number 23 of kilo-gram to the international prototype of kilogram kept atthe BIPM. The comparability of measurement stand-ards of mass laboratory is maintained by internationalcomparisons (e.g. EURAMET key comparisons). Wecarry out research and development related to scalesand weights and offer expert services on the usage ofscales and weights. Our mass laboratories are of highquality and we have scales equipped with automaticweight handlers. Our laboratories are located in Es-poo and Kajaani.

Measurement methodsThe measurement range of mass at MIKES is 1 mg... 2000 kg. The calibrations of weights are performedby using generally accepted weighing methods: thedirect comparison method and the subdivisionmethod. In the first method, the weight is directly com-pared to a standard and in the latter, a set of weightsis calibrated by using one or several weight stand-ards.

mailto:[email protected]



Massa,paine ja virtaus

Lämpötilaja kosteus

Sähkö, aika jaakustiikka

Optiikka Pituus jageometria

KemiaCalibration of weights


Calibration servicesMIKES is capable to calibrate weights of OIML clas-ses E1, E2, and F1, whose nominal masses are atmost 20 kg (E1), 50 kg (E2) and 2000 kg (F1). In ad-dition, MIKES offers calibration services for weightsof lower OIML classes, whose masses are between10 kg and 2000 kg. MIKES also calibrates otherweights such as weights of pressure balances. In thecalibration certificate, the masses are given as con-ventional masses or as true masses. The smallestachievable measurement uncertainties in mass cali-brations are presented in table 1. Weights whosenominal mass is 50 kg or bigger are calibrated atMIKES Kajaani.

Calibration of volume ofweightsWhen calibrating a weight, a correction due to the airbuoyancy has to be made to the weighing result. Themagnitude of the correction depends on the volumeof the weight and on the density of air. In order to beable to make the correction accurately enough, thevolumes of the most accurate weights have to beknown. Mass laboratory calibrates volumes and den-sities of solid artefacts. The density standard is eitherdistilled water or silicon. The measurement methodsis hydrostatic weighing. The measuring equipment issuitable for volume calibration of 2-kg weights orlighter. If needed, volumes of bigger weights can bedetermined by using e.g. dimensional measurements.The measurement uncertainties of volume calibra-tions of weights are presented in table 2.

Table 1. Measurement uncertainties of weight calibrations.

Mass Measurement uncertainty(k=2)

2000 kg *) 3000 mg1000 kg *) 1500 mg500 kg *) 750 mg200 kg *) 300 mg100 kg *) 200 mg50 kg *) 30 mg

20 kg 3.0 mg10 kg 1.5 mg5 kg 1.0 mg2 kg 0.3 mg1 kg 0.05 mg

500 g 0.03 mg200 g 0.02 mg100 g 0.015 mg50 g 0.010 mg20 g 0.008 mg10 g 0.007 mg5 g 0.005 mg2 g 0.004 mg1 g 0.003 mg

500 mg 0.003 mg200 mg 0.002 mg100 mg 0.0015 mg50 mg 0.0015 mg20 mg 0.0010 mg10 mg 0.0008 mg5 mg 0.0008 mg2 mg 0.0008 mg1 mg 0.0008 mg

*) Calibration in MIKES-Kajaani.

Table 2. Measurement uncertainties of calibrations ofweight volumes.

Mass Volume Uncertainty (k=2)1 g – 2 kg 0.1 – 255 cm3 0.000 3 – 0.008 cm3






Chemistry

Calibration of pressuremeasuring devicesMonika Lecklin, Research TechnicianTel. +358 50 410 [email protected]

Sari Saxholm, Senior ScientistTel. +358 50 410 [email protected]

MIKES, Tekniikantie 1, FI-02150 EspooTel. +358 20 722 111www.mikes.fi

Figure 1. Pressure balance is used for the traceable reali-zation of pressure unit.

MIKES has good capabilities to calibrate differentmeasuring devices of pressure. The measuring rangefor gauge pressure is 0 ... 500 MPa and for absolutepressure 0.0005 Pa ... 1.75 MPa. The best measure-ment standards at MIKES are pressure balances,which are used to realise pressure according to its

definition p = F / A, i.e. pressure is force divided byarea. The force is produced by the mass of the pistonof the pressure balance and by the masses of weightsloaded over the piston. The local value for the accel-eration of free fall must be known. The area A is theeffective area of the piston cylinder assembly of thepressure balance.

Pressure balances are used for gauge and negativegauge pressure measurements and for absolutepressure measurements. To cover a wide range ofpressures, several piston cylinder assemblies of dif-ferent sizes are needed in order to be able to realisedifferent pressures and to keep the number of weightsstill easy to handle.

In pressure ranges below the range of pressure bal-ances, capacitive sensors and spinning rotor gaugesare used as measurement standards. The lowestpressures (absolute pressures 0.0005 Pa ... 2 Pa) arecalibrated by using spinning rotor gauges. Thesemeasurements are demanding, as they require longstabilisation and measurement times.

Measurement methods and devices used for pres-sure depend on the pressure range.

Figure 2. Pressure measurements are made in a very broad pressure range, for instance from 10-9 Pascals requiredin particle accelerators to over 109 Pascals, i.e. 1 GPa, pressures used in powder metallurgy. Measuring devices andtheir operational principles are very different in different pressure ranges. The measurement range in MIKES is from0.5 mPa to 500 MPa and is marked with blue bar in the figure.








KemiaCalibration of pressure measuring devices


Figure 3. In practice, measurement of pressure is alwaysmeasuring differential pressure. Depending on the refer-ence point various names are used for pressure and diversedevices used.

Absolute pressureThe ideal vacuum as reference point (vacuumgauges).

Atmospheric pressureAtmospheric pressure is the absolute pressurecaused by the atmosphere so the reference is theideal vacuum (barometers).

Gauge pressureThe reference point is the atmospheric pressure.E.g., the tyre pressure of a car is gauge pressure. Anygauge pressure can be converted to an absolutepressure by adding the momentary atmosphericpressure.

Negative gauge pressureThe reference point is the atmospheric pressure.When converted to absolute pressures, negativegauge pressure is thereby lower than the atmos-pheric pressure. Thus, negative gauge pressuremeans that the objects pressure is lower than thepressure in its environment.

Differential pressurePressure is called as differential pressure especiallywhen the reference pressure is other than the vac-uum or the atmospheric pressure. The referencepressure is then usually called as a line pressure.

Absolute pressuregaseous medium

Pressure range (Pa)

Relative measurementuncertaintyk = 2 (%)

Gauge pressuregaseous medium

Pressure range (Pa)


0.0005 9 100 0.030.001 6 1000 0.010.01 3 10 000 0.0040.1 3 100 000 (0,1 MPa) 0.003

1 2 1 000 000 (1 MPa) 0.002

10 0.5 10 000 000 (10 MPa) 0.004100 0.1 16 000 000 (16 MPa) 0.004

1000 0.01

Figure 4. Piston cylinderassemblies of differentsize for pressure balances.

10 000 0.005100 000 (0.1 MPa) 0.0041 000 000 (1 MPa) 0.004

1 750 000 (1.75 MPa) 0.003

Negative gauge pressuregaseous medium

Pressure range (Pa)


Gauge pressure,in oil medium

Pressure range (Pa)


–100 0.03 500 000 (0.5 MPa) 0.005–1000 0.01 1 000 000 (1 MPa) 0.004

–10 000 0.005 10 000 000 (10 MPa) 0.003–100 000 (–0.1 MPa) 0.004 100 000 000 (100 MPa) 0.003

500 000 000 (500 MPa) 0.01






Chemistry

Calibration of forceand torqueSauli Kilponen, Research TechnicianTel. +358 50 443 [email protected]

Jani Korhonen, Research EngineerTel. +358 50 443 [email protected]

MIKES, Tehdaskatu 15, Puristamo9P19, FI-87100 Kajaani,Tel. +358 50 443 4213,www.mikes.fi

Traceabilityand calibration of force

VTT MIKES-Kajaani performs force calibrations from1 N to 1.1 MN. Calibrated measurement devices areusually force transducers, force measurement de-vices, balances (e.g. hook, wheel weight and airplane)and pull force testers. The smallest measurement un-certainty is 2×10-5.

The calibration of force is based on the ISO 376 stand-ard. The force calibration from 1 N to 110 kN is carriedout in dead weight force standard machines. A deadweight machine is a mechanical structure that gener-ates force by subjecting dead weights to the local grav-itational field. Hydraulic force standard can be used inthe calibrations from 20 kN to 1.1 MN.

The masses that are used in VTT MIKES-Kajaani aretraceable to the national standard of mass, which is inturn traceable to the international prototype of the kil-ogram held in the BIPM. Force traceability is realisedfrom mass calibrations and international comparisons. Figure 1. A 1-MN hydraulic force standard and a 100-kN

direct load force standard. The total equipment height iseight meters, including the load masses below floor level.

Table 1. Measurement ranges for force.

Load method Measurement range Measurement uncertainty (k=2)

Direct load Compression / pulling: 10 N ... 10 kN 2 × 10–5

Direct load Compression / pulling: 10 kN ... 100 kN 5 × 10–5

Hydraulic load Compression / pulling: 20 kN ... 1 MN 1 × 10–4

Field calibration of force 1 N ... 1 MN 5 × 10–4








KemiaCalibration of force and torque


Traceabilityand calibration of torque

MIKES-Kajaani performs calibrations of torque in therange 0.1 Nm ... 20 kNm, the smallest uncertainty be-ing 5×10–4. The calibration of torque is carried out us-ing reference standards for torque or standards basedon reference sensors.

The need for torque calibrations can be classified inthree groups of different types of devices. The moststringent accuracy requirement (< 0.05 % ... 0.5 %) isfor calibration of torque sensors that are used e.g. inmeasurement of torque in research of rotating ma-chines such as pumps and motors. The second groupis devices used for calibration of torque-controlled as-sembly tools. In calibration of these devices, the un-certainty of the torque standard should not exceed 0.5%. The third group is calibration of torque-controlledassembly tools for industries that do not have theirown calibration devices. The calibration uncertaintyfor torque-controlled assembly tools is typically from1 % to 10 %.

There exist only a few standards for torque calibra-tions. For torque-controlled assembly tools is thestandard ISO 6789, which however mainly describestest methods but also defines a calibration procedure.There is no standard for devices used for calibrationof torque-controlled assembly tools. For torque sen-sors, there exists the recommendation Euramet/cg-14.

Torque is a derived quantity that consists of knownmasses and a known length of a lever arm. Eventhough traceability for masses and length can beachieved separately, verifying the consistency oftorque in entity is mainly verifying the consistency oftorque in entity is mainly based on interlaboratorycomparisons

Figure 2. A 2-kNm torque standard used for comparisonmeasurements in the range 100 Nm – 2 kNm and forcalibration of torque sensors.

Figure 3. A 20-kNm torque standard based ona reference sensor.

Torque standard Measurement range Measurement uncertainty (k=2)Lever - mass 0.1 ... 10 Nm right / left 5 . 10–4

Lever - mass 10 ... 2000 Nm right / left 5 . 10–4

Reference standard 2 ... 20 kNm right / left 5 . 10–4






Chemistry

Water flow metercalibrationsMika Huovinen, ResearcherTel. +358 50 415 [email protected]

Timo Nissilä, Research EngineerTel. +358 50 443 [email protected]

MIKES, Tehdaskatu 15, Puristamo 9P19,FI-87100 Kajaani, Tel. +358 50 443 4213www.mikes.fi

Calibration providesreliabilityAccurate liquid flow measurements are needed inmany areas of industry, such as process, mining andenergy industry. To maintain global competitivenessand high quality of the end products, accurate liquidflow measurements make it possible to optimise dif-ferent industrial processes and in this way reduce rawmaterial consumption and emissions to environment.Regular calibration and stability tracking of liquid flowmeters are essential part of measurement reliability,regardless of the application.

Figure 1. Graphical user interface of the D200 liquidflow calibration rig.








KemiaWater flow meter calibrations


TraceabilityThe most important activities of MIKES Kajaani are toimplement the traceability of the flow measurements inFinland, maintain liquid flow measurement standards,and provide calibration and expert services. These areachieved by participating in international and domesticresearch and intercomparisons projects. The MIKES’sliquid flow calibration laboratory’s quality managementsystem is based on the ISO/IEC 17025 standard.

Calibration servicesMIKES Kajaani has three different calibration rigs forliquid flow calibrations. One of the rigs is the nationalmeasurement standard of flow. In this rig, the measur-ing principle is gravimetric and the measurements car-ried out are traceable to the national standards ofmass, temperature and time.

The gravimetric reference standard of water flow isbased on weighing the water. In the measurements,water is first continuously pumped up to a constanthead tank located 20 m above ground level. The wa-ter level is held constant in the tank by sufficientoverflow and by adjusting the water flow in a meas-uring pipe section, where the flow meters under testare placed. The calibration is done by comparing theresults of the balance and the meter under test read-ing.

In the closed loop type calibration rigs, the referencemeters are usually magnetic or coriolis mass flowmeters. In these rigs, the source of traceability up toDN200 is based on the national flow standard. Forpipe sizes DN200 >, the source of traceability is aforeign NMI, typically PTB from Germany.

The measuring principles, ranges, and reachablemeasurement uncertainties are shown in Table 1.

Table 1. Measuring ranges of the liquid flow calibration rigs and the measurement uncertainty.

Equipment Measuringprinciple

Pipe sizes Volume flow Pressure Measurementuncertainty (k=2)

D100 reference meter DN 15DN 50

0.3 l/s … 20 l/s <0.7 MPa 0.3 %

D500 reference meter DN 150DN 500

7 l/s … 750 l/s <0.5 MPa 0.3 %

D200 gravimetric DN 10DN 50DN 100DN 200

0.1 l/s … 200 l/s 0.2 MPa 0.03 %

For pulp and paper industry, MIKES Kajaani has a mass circulating rig applied with a cooling system. Con-sistency area 0–12 % and flow speed 0.5–3 m/s.

Figure 2. Part of the D500 liquid flow calibration rig.






Chemistry

Calibration of gas flowsand density of liquidsRichard Högström, Senior ScientistTel. +358 50 303 [email protected]

Heikki Kajastie, ResearcherTel. +358 50 410 [email protected]


Calibration gives reliabilityNowadays, measurement of small gas flows isneeded in various applications. For instance, in healthcare and medical industry is very important to assurethe safety of customers. In order to maintain interna-tional competiveness and to guarantee the high qual-ity of products, the accuracy of gas flow measure-ments in process industry has to be reliably verified.No matter what the application is, the regular calibra-tion and stability monitoring of gas flowmeters is anessential part of quality control. MIKES calibrates gasflowmeters in the flow range 5 ml/min ... 110 l/min andoffers research and expert services in the field of gasflow measurements and their reliability.

TraceabilityMIKES provides circumstances for traceable gas flowmeasurements in Finland by developing and main-taining standards for gas flows and offers calibrationand expert services.

The traceability of gas flows at MIKES is based on adynamic weighing system, DWS developed at theflow laboratory of MIKES. The measurements per-formed using this system are traceable to the nationalstandards of mass and time. The DWS equipment isused to calibrate measurement standards based onlaminar flow elements (LFE) and customers’ deviceswhose relative accuracy level is better than 1 %.

The high level of our gas flow measurement activitiesis maintained by actively participating in internationalresearch projects and comparisons and by carryingout own research projects in this field.








KemiaCalibration of gas flows and density of liquids


Calibration services

If the relative accuracy level of a gas flowmeter is bet-ter than 1 %, the DWS equipment will be used in thecalibration. Typical examples of such flowmeters arehigh-quality laminar flow elements and some piston-cylinder volume flowmeters.

Most of our customers’ flowmeters are calibrated atMIKES using the LFE calibration equipment. It ismuch more convenient to use than the DWS equip-ment and it does not have such a strict tolerances forenvironmental conditions. Performing of calibrationsare thus more flexible and faster. The equipment hasproven to be well suited for calibration of gas flowme-ters having relative accuracy above 1 %. Such metersinclude thermal mass flowmeters and controllers.

Furthermore, MIKES performs liquid density meas-urements. We calibrate for instance areometers anddensity meters based on vibrations and determinedensities of customers own liquid samples in the den-sity range 600 kg/m3 ... 2000 kg/m3.

Table 1. Measurement ranges and best achievable calibration uncertainties at MIKES.

Quantity Measurement range Measurement uncertainty (k=2)

Mass flow (DWS) 0.1 mg/s ... 625 mg/s 0.3 % ... 0.8 %

Mass flow (LFE) 0.1 mg/s ... 625 mg/s 0.4 % ... 0.9 %

Volume flow (LFE) 5 ml/min ... 30 l/min 0.4 % ... 0.9 %

Density of liquid (LDCS) 600 kg/m3 ... 2000 kg/m3 15 ppm

Calibration of areometers (HCS) 600 kg/m3 ... 2000 kg/m3 0.05 %

DWS = Dynamic weighing system,LFE = Laminar flow elementLDCS = Liquid density calibration systemHCS = Hydrometer calibration system






Chemistry

Acceleration of free fallMarkku Poutanen, Prof.Tel. +358 29 531 [email protected]

Mirjam Bilker-KoivulaSenior Research ScientistTel. +358 29 531 [email protected]

Hannu RuotsalainenSenior Research ScientistTel. +358 29 531 [email protected]

Finnish Geospatial Research Institute,FGI, Geodeetinrinne 2, FI-02430 Masala,Tel. +358 29 530 1100,www.fgi.fi

Finnish Geospatial ResearchInstitute, FGIThe Finnish Geospatial Research Institute, FGI, ofthe National Land Survey of Finland maintains meas-urement standards for geodetic and photogrammetricmeasurements and is the National Standards Labor-atory of acceleration of free fall and length. The FGItakes care of the fundamental measurements in Finn-ish cartography and of geographical information me-trology and carries out scientific research in geodesy,geographic information sciences, positioning, naviga-tion, photogrammetry and remote sensing.

Methods and traceabilityThe national measurement standard is the absolutegravimeter FG5-221. Its results are directly traceableto length and time standards. We have participated inall international comparisons since the year 1989. Ata customer’s site, the measurements are usually per-formed with a relative gravimeter, measuring thegravity difference with respect to a point with knowngravity.

Acceleration of freefall andgravityThe acceleration of free fall depends on location andtime. The time dependence originates from tidalforces (variation in Finland 3 μm s–2) and from massvariations of groundwater and atmosphere (at leastan order of magnitude smaller). When the most im-portant time variations are removed from the acceler-ation of free fall by using agreed methods, the resultis the acceleration due to gravity, which can betreated as a time independent quantity.

Figure 1. Acceleration of free fall in Finland, unit ms–2.




http://www.fgi.fi/





KemiaAcceleration of free fall


Calibration services anduncertaintyWe measure gravity at requested sites and report thevalue for the acceleration of free fall. The time varia-tion is included in the uncertainty of 4 μm s–2 (k=2). Ifneeded, we supply an accurate value for gravity (thesmallest uncertainty is 0.008 μm s–2) and methods topredict the time variation (the smallest uncertainty0.10 μm s–2). We maintain an open calibration linewhere customers can verify their gravimeters.

Research, developmentand reportingWe carry out research and develop national infra-structure for measurements of gravity and accelera-tion of free fall for all applications (e.g. geodesy, geo-physics and geology). With the help of the 30 000points in the national gravity grid, the acceleration offree fall can be estimated with an accuracy of 0.1 mms–2 without any new measurements. We have per-formed measurements using absolute gravimeters in20 countries.

Figure 2. A measurement using Figure 3. The absolute gravimeter FG5X-221 is based on a relative gravimeter. a free fall experiment.

Figure 4. Superconducting gravimeter (Metsähovi, Kirkkonummi) registerseven 0.1 nm s–2 variations in the acceleration of free fall.






Chemistry

Calibration ofhygrometersRichard Högström, Senior ScientistTel. +358 50 303 [email protected]

Heikki Kajastie, ResearcherTel. +358 50 410 [email protected]


Reliability from calibrationsReliability of humidity measurements is important,e.g. in storage of wood, paper, food, etc. in aviationand environmental monitoring as well as in diversefields of industry and research. Calibration of hygro-meters at regular intervals and monitoring their stabil-ity is an essential part of verification of measurements.

MIKES provides high-quality calibration services forinstruments measuring humidity of gases and expertservices on research and development related to hu-midity measurements and their reliability.

Traceability to humiditymeasurementsMIKES creates conditions for traceable humiditymeasurements in Finland by developing and main-taining measurement standards for humidity and byoffering calibration and expert services.

The high quality of the humidity laboratory is main-tained by taking part in international research andcomparison projects and by carrying out own re-search projects.








KemiaCalibration of hygrometers


TraceabilityTraceability of humidity measurements is based on adew-point temperature scale. The scale is realised byusing a humidity generator, which is the nationalmeasurement standard in Finland.

The core of a dew-point generator is a saturator inwhich total saturation of air with respect to water or iceis reached. The dew point temperature of the air com-ing out of the generator is calculated from the satura-tor temperature and from the pressure difference be-tween the saturator and the device under calibration.When saturated air is led into the measurement cham-ber of the generator, the equipment is also suitable forcalibration of relative humidity sensors.

Figure 1. Calibration of chilled mirror hygrometers.

The dew-point meter under calibration is directly con-nected to the dew-point generator. In calibration of arelative humidity sensor, the sensor is placed in themeasurement chamber system. The reading of thesensor is compared to the value of relative humiditythat is calculated from the dew-point temperature andthe air temperature inside the chamber.

Calibration servicesMost dew-point meters are calibrated using a dew-point generator. The measurement standards of hu-midity laboratory at MIKES cover the dew-point tem-perature range –80 °C to +84 °C. Dew-point calibra-tions are also carried out as comparison calibrationsin calibrators, for instance for capacitive dew-pointmeters.

Most relative humidity sensors are calibrated in a cli-matic chamber. The dew-point temperature and theair temperature in the chamber are measured by us-ing a chilled mirror hygrometer and a digital thermom-eter, respectively. The relative humidity is calculatedfrom measured temperature and dew-point tempera-ture. If the achievable uncertainty is not sufficient orthe temperature range extends to below +10 °C, thecalibration is performed using a humidity generator.Relative humidity sensors are calibrated in the range10 %rh to 95 %rh at temperatures between –20 °Cand +85 °C.

In cases of other humidity quantities, calibrationsare performed with the same equipment the relativehumidity calibration systems. The values of thesequantities are calculated from measured dew pointtemperature, temperature, and pressure.

Quantity Measurement range Measurement uncertainty (k=2)Dew-point temperature –80 °C ... –60 °C

–60 °C ... +84 °C0.2 °C ... 0.1 °C0.05 °C ... 0.06 °C

Relative humidity 10 %rh ... 95 %rh(–20 °C ... +85 °C)

0.1 %rh ... 1.0 %rh(generator)

Relative humidity 10 %rh ... 95 %rh(+10 °C ... +85 °C)

0.4 %rh ... 2.0 %rh(climate chamber)






Chemistry

Calibration of radiationthermometersOssi Hahtela, Senior ScientistTel. +358 50 303 [email protected]


Measurement methodsBlackbody radiators are used in calibration of radia-tion thermometers. The operation range of MIKES ra-diators is –40 °C ... 1500 °C.

The temperature of a blackbody radiator can bemeasured using e.g. a temperature sensor that is em-bedded in the radiator wall. When calculating the ra-diation temperature from the measured temperature,the emissivity of the wall and bottom materials of theradiating cavity and the geometry of the blackbody ra-diator as well as the temperature gradients are taken

into account. The radiation temperature measured bya radiation thermometer is often lower than the sur-face temperature of the measured object, since thesurface emissivity is usually lower than the emissivityof an ideal blackbody (the emissivity of a blackbody is1 but the emissivity of a glossy copper surface is 0.1).

In MIKES, radiation thermometers are calibrated byusing either a calibrated reference pyrometer or refe-rence radiators.







KemiaCalibration of radiation thermometers


TraceabilityThe international temperature scale ITS-90 is realisedabove the temperature of 962 °C with a reference py-rometer and fixed-point radiators (962 °C, 1064 °Cand 1085 °C). Of these fixed-points MIKES has thefirst and the last one, which are the freezing points ofsilver (figure 1) and copper. Below the temperature of962 °C, ITS-90 is realised by using resistance ther-mometers instead of a pyrometer. The referenceequipment for radiation temperatures between –40 °C… 962 °C at MIKES are based on resistance ther-mometers calibrated according to the ITS-90.

Size-of-source-effectThe size of the radiation source (size-of-source-ef-fect, SSE) affects the calibration results of a radiationthermometer. A radiation thermometer detects ther-mal radiation also outside the blackbody radiator orthe object to be measured. The significance of thisadditional thermal radiation depends on the construc-tion of the optics (figure 2).

On demand, the size-of-source-effect is measured atMIKES.

Figure 1. A silver cell that is used in thecalibration of a reference pyrometer.

Figure 2. SSE: In this example, a pyrometerdetects lower temperatures when the apertureof the radiator is less than 15 mm and thetemperature of the radiator is higher thanambient temperature.

Vocabulary • reference meter: measurement standard • pyrometer: radiation thermometer (infrared thermometer) • a black-body radiator does not reflect at all radiation coming from the outside. The temperature of an object depends only from theheat energy brought to the object and hence its radiation intensity is proportional to the temperature of the object.

Outer cover graphite

Inner cover graphite

Silver






Chemistry

Fixed point calibration of plati-num resistance thermometersOssi Hahtela, Senior ScientistTel. +358 50 303 [email protected]


Calibration objectsand methods

Standard platinum resistance thermometers (SPRT)of good quality (i.e. stable) are calibrated at the fixedpoints of the ITS-90 temperature scale. A fixed-pointcell (Figure 1) usually contains pure metal, e.g. tin,zinc, aluminium or silver (Table 1) sealed in a cruciblef purified graphite. The purity of the metal is typicallyca. 99.99995 %. The graphite crucible is enclosed ina fused quartz tube.

The fixed-point cell is placed in a vertical tube furnaceand the temperature is slowly raised until the meltingis complete. At this stage, the furnace temperature isreduced to a value slightly below the melt tempera-ture in order to start solidification. When the metal isin a supercooled state, the thermometer to be cali-brated is carefully inserted into the cell. The thermom-eter is coupled to a resistance bridge using four-wirecoupling. The solidification state can be maintainedup to 10 hours (Figure 2) and the temperature of thefixed point cell stays within ±0.5 mK.

The resistance bridge is used to measure the electri-cal resistance of the thermometer during the solidifi-cation state. The thermometers are usually calibratedusing three or five different fixed points.

Figure 1. Pt25-sensor (SPRT) in a fixed-point cell.







KemiaFixed point calibration of platinum resistance thermometers


Calculation of calibrationcoefficientsThe temperature T90 is determined according to theITS-90 temperature scale. First a resistance ratioW(T90) = R(T90) / R(T0.01°C) is calculated by dividingthe sensor resistance at a given fixed point by the re-sistance value at the water triple point. A deviationfunction of the resistance ratio and calibration con-stants (a, b,) are determined for each sensor undercalibration. The deviation function can be e.g.

W(T90) – Wr(T90) = a[W(T90) – 1] + b[W(T90) – 1]2

where W r(T90) is a reference function given in the ITS-90 scale. The deviation function to be used and thenumber of calibration constants depend on the tem-perature range and the used fixed points.

The deviation function can also be used to determineany temperature between the fixed points when theconstants a and b are known. In this case, W(T90) isfirst determined at the unknown temperature and theresulting Wr is used to calculate T90.

Uncertainty in fixed pointcalibrationThe uncertainties of the fixed points at MIKES are be-tween 0.0002 ... 0.010 °C. The lower limit is reachedat the triple point of water and the upper limit at thefixed points of aluminium and silver. The uncertaintyof the resistance thermometer calibrations is largersince it includes also uncertainties of the calibrationequipment (resistance bridge, reference resistor) andthe stability of the thermometer during the calibration.

Other fixed point calibrationsNoble metal thermocouples of B-, R- and S-type arealso calibrated at fixed points. The highest fixed-pointtemperature is the freezing point of copper at1084.62 °C.

TraceabilityThe MIKES fixed points are part of the realisation ofthe international ITS-90 temperature scale. The sta-bility of the fixed-point cells are monitored and thetemperatures they provide are compared to the tem-peratures from similar cells at our own and foreign la-boratories.

Table 1. MIKES fixed points for resistance thermometers.

Subtance Temperature (°C) State *

Argon (Ar) –189.3442 t

Mercury (Hg) –38.8344 t

Water (H2O) 0.01 t

Gallium (Ga) 29.7646 m

Indium (In) 156.5985 f

Tin (Sn) 231.928 f

Zinc (Zn) 419.527 f

Aluminium (Al) 660.323 f

Silver (Ag) 961.78 f

* t = triple point, m = melting point, f = freezing point

Figure 2. Freezing curve of zinc.

Abbreviations:Pt25 = 25-ohm platinum resistance thermometerHTPRT = high temperature platinum resistance ther-mometer

Time (h)

Tem

pera

ture

(°C

)






Chemistry

Calibration of directvoltage and currentPekka Immonen, ResearcherTel. +358 50 410 [email protected]

Ilkka Iisakka, ResearcherTel. +358 50 410 [email protected]

MIKES, Tekniikantie 1, FI-02150Espoo, Tel. +358 20 722 111,www.mikes.fi

Accuracy of almost all electrical measuring instru-ments is based on traceability of direct voltage andresistance. MIKES maintains the national standard ofdirect voltage and direct current in Finland. The unitof direct voltage, volt, is determined very accurately(repeatability even 10–10) by using Josephson voltagestandard. The volt is transferred from the Josephsonstandard to Zener working standards and further tocalibrators and multimeters. The measurement rangeis extended above 10 V by using resistive voltage di-viders. In practice, traceability of direct current comesfrom voltage and resistance using Ohm’s law. Trace-ability of currents smaller than 100 pA can be realizedalso by charging a capacitor by a linearly increasingvoltage. One research topic is the development of aquantum standard for direct current based on single-electron phenomena in nanostructures.

The methods and measuring instruments developedat MIKES are of high international level. One demon-stration of this is the excellent success in internationalcomparison measurements with other national me-trology institutes. Moreover, MIKES research on di-rect current metrology is in the international front line.Most important research topics are development ofvoltage standards based on microelectromechanicalsystems (MEMS) and closing the so-called quantummetrological triangle to prove by Ohm’s law that thereis a mutual agreement between the quantum stand-ards of electric current, voltage, and resistance.

Figure 1. The traceability of direct current is based on aJosephson standard cooled in liquid helium.






KemiaCalibration of direct voltage and current


Calibration servicesIn addition to accredited calibration laboratories,MIKES provides services to all customers requiringlow measurement uncertainty. The most importantcalibration subjects in the field of direct current aresolid-state voltage standards, dc- and multifunctioncalibrators as well as precision multimeters. Zenerstandards are calibrated usually by comparison toMIKES working standards. A relay scanner connectsthe voltage difference of the standards to a nano-volt-meter and the results are recorded at regular intervalsfor a couple of weeks. Routine calibrations of directvoltage and current ranges of calibrators and multi-meters are carried out using a reference multi-meterand a multifunction calibrator. The measuring rangesand uncertainties of calibrations for voltages up to1 kV are presented in table 1.

Direct current calibrations are usually performed forcurrents between 0.1 mA and 1 A with relative uncer-tainty of 10 μA/A and for 100 fA – 100 μA with uncer-tainties varying from 600 μA/A to 20 μA/A.

When lower uncertainties are needed, calibrationscan be performed by using directly the MIKES Jo-sephson standard. On special order, calibrations ofmultimeters and calibrators can be carried out usingdirectly the Josephson and Zener standards and a re-sistive voltage divider. Direct current calibrations re-quiring lower than 10 μA/A uncertainties and meas-urements above 1 A current levels can be performedby measuring the voltage across a resistance stand-ard. The lowest achievable uncertainties of thesemeasurements are listed in table 2. Resistive voltagedividers are calibrated by comparison to the MIKESreference divider or with the Josephson standard.The value of voltage or current together with its un-certainty is given in the calibration certificate.

Stability or temperature dependence measurementscan be carried out on customer’s request. MIKES fol-lows the long-term stability of customers’ voltagestandards and can attach follow-up results to the cal-ibration certificate if needed.

In addition to the calibration, we carry out special as-signments related to voltage and current measure-ments and actively participate in research and devel-opment projects in these fields.

Figure 2. A Zener direct voltage standard.

Table 1. The smallest measurement uncertainties for the most common direct voltage calibrations. By using special tech-niques, even much lower calibration uncertainties can be achieved.

Device Zener-standard Calibrator or multimeterVoltage (V) 1 1.018 10 0 ... 10 10 ... 100 100 ... 1000Uncertainty (μV) 0.2 0.2 2 0.3 ... 20 70 ... 610 1000 ... 10000

Table 2. The smallest uncertainties of direct current calibrations for currents less than 20 A.

Device Zener-standard Calibrator or multimeterCurrent < 0.1 pA (0.1 ... 100) pA (1 ... 100) nA (0.1 ... 100) μA (0.1 ... 100) mA (0.1 ... 20) AUncertainty 0.1 fA (1 ... 0.6) mA/A (0.1 ... 2) pA 20 μA/A 5 μA/A (5 ... 20) μA/A






Chemistry

Calibration of alternat-ing voltage and currentIlkka Iisakka, ResearcherTel. +358 50 410 [email protected]


In society, many important functions such as themeasurement of electrical energy, which is suppliedby electrical power networks to consumers, are basedon the accurate measurement of alternating voltageand current. MIKES is responsible for the traceabilityof alternating voltage and current in Finland. Thetraceability of the most accurate measurements of ACvoltage is based on thermal converters and range re-sistors acting as secondary standards. The traceabil-ity of AC voltage and AC current ranges of multifunc-tional calibrators and precision multimeters comesfrom AC voltage standards calibrated at MIKES or atother national metrology institutes and from their cal-ibrated range and shunt resistors. The reliability of re-sults is verified by taking part in international compar-isons.

MIKES performs also high-level research on AC volt-age metrology. Especially, MIKES is at the top of in-ternational metrology research in development workof two different types of AC voltage standards in do-mestic collaboration with VTT: a primary standard forAC voltage based on Josephson effect and an ACvoltage working standard based on micromechanicalsensors (MEMS).

Figure 1. Equipment of the national metrology laboratory foralternating voltage and current.






KemiaCalibration of alternating voltage and current standards


Calibration servicesMIKES has accurate AC voltage meters and calibra-tors as working standards. We calibrate voltages from1 mV to 1000 V in a frequency range from 10 Hz to 1MHz and currents from 100 μA to 20 A in a frequencyrange from 50 Hz to 10 kHz (up to 8000 A in the fre-quency range 45 Hz …. 65 Hz). Typical devices thatwe calibrate include thermal converters, precisionmultimeters and calibrators, and current sources andsensors. In addition, other devices can be calibratedin agreement with a customer. Usually customer’s ACvoltage and current devices are calibrated by compar-ing their AC/DC difference to the AC/DC difference ofa Fluke 5790A working standard and Fluke A40AC/DC current shunts or by comparing the rms valuesdirectly to the rms value of a MIKES device. Themeasuring ranges and smallest achievable uncertain-ties for these calibrations are shown in the tables be-low.

Figure 2. AC-DC-relay and two thermal converters.

Table 1. Measurement ranges and smallest relative uncertainties in parts per millions from measurement results (μV/V) forthe alternating voltage range of a multifunctional calibrator.

Frequency

10 Hz 20 Hz 40 Hz 53 Hz 400 Hz 1 kHz 10 kHz 20 kHz 50 kHz 100 kHz 500 kHz 1 MHz

1 mV 1200 1200 1200 – 1200 1200 1200 1200 1200 1400 3300 50002 mV 590 590 590 – 590 590 590 590 590 680 1600 460020 mV 130 120 120 – 120 120 120 120 120 140 350 580100 mV 50 50 30 – 30 30 30 30 35 60 220 4501 V 40 40 20 – 15 15 15 15 30 50 110 44010 V 40 40 20 – 20 20 20 20 30 45 140 400100 V 40 40 30 – 20 20 20 20 35 40 – –1000 V – – 50 50 50 – – – – – – –

Table 2. Measurement ranges and smallest relative uncertainties in parts per million of measurement result (μA/A) for thealternating current range of a multifunctional calibrator.

Taajuus

40 Hz 400 Hz 1 kHz 5 kHz 10 kHz

100 µA 80 80 80 90 110

1 mA 35 35 35 35 4010 mA 35 35 35 35 50

100 mA 35 35 35 35 601 A 35 35 35 50 11010 A 110 110 110 150 21020 A 110 110 110 180 260

Cur

rent

(rms

valu

e)Vo

ltage

(rms

valu

e)






Chemistry

Calibration of capacitanceand inductance standardsIlkka Iisakka, ResearcherTel. +358 50 410 [email protected]


Capacitors and inductors are essential componentsin electronics. Moreover, capacitive sensors are usedin many high-precision measurements: e.g. in meas-urements of position, distance and level. For calibra-tion of precision LCR meters, inductance and capaci-tance standards are needed. Therefore, traceablemeasurements of capacitance and inductance are ofutmost importance. In Finland, MIKES is responsiblefor the traceability of capacitance and inductance.

In MIKES, ac coaxial bridges are used to providetraceability of the decade capacitance standards inthe range 10 pF – 1 μF to resistance and frequency

Figure 1. Traceability to capacitance from resistanceand frequency in MIKES impedance laboratory.

— quantities which are maintained at MIKES. The re-liability of the results is verified by international com-parisons and by taking advantage of capacitancemeasurement services at the BIPM. The capacitancevalues between calibration points are interpolated byusing measuring bridges based on inductive dividers.

Inductance standards in the range 100 μH – 100 mHare traceable to the MIKES capacitance and resistan-ce standards.

Calibration servicesMIKES calibrates capacitance standards in the range0 pF … 1 μF using a very stable capacitance bridgeand reference capacitance standards. The measure-ments are usually carried out at 1 kHz but other meas-urement frequencies are also possible. The calibra-tion is performed using either two-terminal or three-terminal method by connecting the calibrated capaci-tance standard through a 16-channel coaxial relay tothe capacitance bridge and by measuring automati-cally for about two or three days. The device undercalibration is placed together with a Pt-100 sensorinto avolume having a constant temperature. Temper-ature is varied during the measurement by about oneor two degrees in order to measure the temperaturecoefficient of the device under calibration. The resultsare corrected to the temperature of 23 °C.

Traceability of inductance standards at MIKES is ba-sed on the link to the capacitance (100 pF) standards,which are calibrated at BIPM and the resistancestandards, calibrated from the Quantum Hall Re-sistance in MIKES. The 100 mH inductance is linkedto capacitance standards at 1 kHz and 1.59 kHz withthe use of series resonance method, where 253 nFand 100 nF capacitors are used as references.






KemiaCalibration of capacitance and inductance standards


Sampling method, which is based on the use of twoDVMs is used to define the values of inductance stand-ards in the range 100 μH – 10 mH. Impedance of thecalibrated inductors is compared with the impedanceof the reference resistor, by measurements of the volt-age ratios at frequencies below 1 kHz.

In addition to the calibration of capacitance and induct-ance standards, we carry out special assignments re-lated to impedance measurements and actively partic-ipate

Figure 2. AH2500A measuring bridge and a 1-nF capaci-tance standard under calibration.

Table 1. Measuring ranges and smallest calibration uncertainties at MIKES for calibration of capacitive standards at 1 kHzfrequency. The expanded relative uncertainty (k = 2) is expressed as parts per million of measured capacitance.

Capasitance value 10 pF 100 pF 1 nF 10 nF 100 nF

Relative uncertainty(µF/F)

5 5 10 30 100

Table 2. Measuring ranges and smallest calibration uncertainties at MIKES for calibration of capacitive standards that havecapacitance values smaller than 10 pF or larger than 100 nF or whose value is not even decade. The expanded relativeuncertainty (k = 2) is expressed as parts per million of measured capacitance. For capacitances lower than 10 pF a basecapacitance of 5 aF is added to the uncertainty.

Capasitance value 0 pF – 10 pF 10 pF – 1 nF 1 nF – 10 nF 10 nF – 100 nF 100 nF – 1 μF

Relative uncertainty(µF/F)

10 (+ 5 aF) 10 30 200 400

Table 3. Measurement methods, inductance values, and reference standards used in calibration of inductance standardsat 1 kHz.

Method Inductance Impedance 1 kHz Reference Uncertainty 2s

Relative uncertainty(µF/F) 5 5 10 30

2 DVM 0.1 mH 1 W 1 W 50

2 DVM 1 mH 10 W 10 W 50

2 DVM / SR 10 mH 100 W 100 W 20

SR / 2 DVM 100 mH 1 kW 253 nF / 100 W 20






Chemistry

Calibration of resistanceIlkka Iisakka, ResearcherTel. +358 50 410 [email protected]


Resistance is the most important quantity of electricalmeasurements together with direct voltage. In addi-tion to resistance calibrations, resistance standardsare needed for providing traceability to other electricalquantities. MIKES is the national standards laboratoryof resistance. The traceability of resistance standardsat MIKES is based on its own quantum Hall standard,which connects the unit of resistance to the values ofphysical constants with a relative uncertainty of 10–8.The dissemination to secondary and working stand-ards, which are stored in oil or air baths, is performedby using a cryogenic current comparator or a directcurrent comparator resistance bridge. Traceability ofresistance standards with value above 1 GΩ is real-ized by using a modified Wheatstone bridge.

The accuracy of MIKES’s resistance standard calibra-tions is at high international level, confirmed by goodresults in international resistance comparisons.MIKES has also participated in coordination of inter-national key comparisons, in which the accurate re-sistance transfer standards developed at MIKEShave been used.







KemiaCalibration of resistance


Calibration servicesIn addition to accredited calibration laboratories,MIKES provides services to all customers requiringvery low measurement uncertainty. In resistance cal-ibration, the resistance of the device under calibrationis measured and the uncertainty of the measurementresult is calculated. On demand, temperature, power,or voltage dependence of resistance standards canbe determined, too. MIKES follows the long-term sta-bility of customer’s resistance standards and when re-quested attaches the results to the calibration certifi-cates. In addition to resistance standards, other cali-bration services for calibration of precision multime-ters and multifunction calibrators are offered.

In the range 0.0001 Ω ... 100 MΩ, the resistance stan-dards are calibrated by comparing them to the prima-

ry and working standards of MIKES by using a MI6242B resistance bridge. When special accuracy isneeded, the measurements can be carried out by us-ing a cryogenic current comparator. In the range 1MΩ ... 100 TΩ, a modified Wheatstone bridge is used.During the calibration, the resistance standards areplaced in a thermal bath. Either two point or four pointmeasurements are used and when needed a guardedmeasurement is carried out. The resistance ranges ofmultimeters are calibrated by using MIKES multime-ters.

In addition to calibrations, we provide special assign-ments related to resistance measurements and ac-tively participate in research and development pro-jects in this field.

Figure 1. Measurement ranges and measurement uncertainties for resistance standards.

Unc

erta

inty

ppm

Resistance to be calibrated/ Ω

Resistance standards by cryogenic current comparatorResistance standards by direct current resistance bridgesMultimeters by resistance standardsCalibrators by direct current resistance bridges






Chemistry

Calibration of power andenergy at line frequencyEsa-Pekka SuomalainenSenior Scientist,Tel. +358 50 382 [email protected]

Tapio Lehtonen, ResearcherTel. +358 50 511 [email protected]

Pekka Immonen, ResearcherTel. +358 50 410 [email protected]

MIKES, Tekniikantie 1,FI-02150 Espoo,Tel. +358 20 722 111,www.mikes.fi

The measurement of electric energy consumptionhas a huge economic importance. Through the de-velopment of electric energy market, the importanceof measurement accuracy and traceability is furtheremphasised. Accurate electric power standards arerequired in the calibration of energy meters. At MI-KES, measurements of electric power at 50 Hz aretraceable to SI units through a sampling powerstandard. Calibrations are performed using eithersingle-phase or three-phase measurements. Typi-cal devices that we calibrate are electric power me-ters and converters.

At MIKES power laboratory, the traceability of elec-tric power at 50 Hz is based on direct voltage froma Josephson standard and resistance realised by aquantum Hall equipment. The sampling power stan-dard consists of two 8½ digit voltmeters, which areaccurately synchronised. Currents smaller than 20A are converted to voltages using specially con-structed shunt resistors, whose resistance valuesare traceable to the quantum Hall resistance stand-ard. Because of the construction of the shunts, theirfrequency dependence is very small. Measurementresults of voltage meters are based on fast samplingand are traceable to the Josephson voltage stand-ard. The same measurement equipment with a cur-rent sensor based on a Rogowski coil is used tomeasure currents and current ratios up to 8000 A.The measurement uncertainty of the MIKES powerreference equipment is 0.005 % at its best.

Figure 1. In power and energy measurements, traceabilityfor large currents is also needed. Parts of 8000 A meas-uring setup based on a Rogowski coil

The methods and equipment of MIKES power labora-tory represent international top quality. The high qualityof measurements is verified by taking part in interna-tional comparison measurements together with na-tional metrology laboratories from other countries.MIKES is also an active member in different expertworking groups at international level and takes part innational as well as international joint research projects.Several projects are in the European Metrology Re-search Programmes EMRP and EMPIR.









KemiaCalibration of power and energy at line frequency


Calibration servicesMIKES calibrates especially reference standards ofcustomers who need the best available measuringaccuracy. Typical instruments are power comparatorsand converters. The calibrations are performed byconnecting the same current and voltage to the cus-tomer’s device and the reference meter of MIKES. Ifnecessary, effect of the power source used in the cal-ibrations is minimized by accurately synchronising themeters. The reference meter used in the calibrationsis either a single-phase sampling power standard ora three-phase power comparator.

In addition to power standards, we calibrate currentand voltage transformers and transducers up to 200kV voltage and 8 kA current. We carry out special as-signments related to the measurement of electricpower and energy and take part in research and de-velopment cooperation projects in this field. More-over, we organise educational opportunities in thisfield and custom tailored training.

Figure 2. A coaxial shunt resistor of the sampling power standard.

Table 1. Measuring ranges and calibration uncertainties at MIKES for calibrations of power and energy at line frequency.

Measured quantity Expanded relative uncertainty (k = 2)Single phase, 30 V – 500 V, 5 mA – 10 AActive power 50 μW/VAReactive power 100 μvar/VA3-phase, 50 V – 350 V, 5 mA – 12 AActive power 120 μW/VAReactive power 250 μvar/VAActive power 120 μWh/VAhReactive power 250 μvarh/VAh






Chemistry

RF- and microwavecalibrationsKari Ojasalo, ResearcherTel. +358 50 410 [email protected]

Jari Hällström, Senior ScientistTel. +358 50 382 [email protected]


The importance of measurement reliability is empha-sized along with the continuously increasing amountof applications in RF- and microwave ranges. MIKESis the national metrology institute in this field and of-fers traceability with low uncertainty to internationallyaccepted measurement standards in RF and micro-wave power measurements and measurements of Sparameter (reflection and attenuation). We calibratepower sensors and attenuators for instance.

Our calibration equipment is equipped with precisiontype N connectors, thus our measurement range ex-tends to 18 GHz. The measurements and the analysisof results are mainly automated. The measurementsare carried out in a controlled 23 °C temperature in anelectromagnetically shielded room.

The high standard of the measurements is verified byactively taking part in international comparisons to-gether with other national metrology institutes. Thetraceability is based on power and attenuation cali-brations at NPL (National Physical Laboratory) in U.K.and on the primary standards at MIKES.

Figure 1. Measurement ofpower sensors.








KemiaRF- and microwave calibrations


Calibration servicesPowerThe calibration coefficients of sensors are determinedwith measurement equipment based on a power di-vider. Measurement of reflection coefficient by usinga vector network analyser is included in the sensorcalibration. Typically, calibration takes five workdays.The calibration of the absolute power of a power ref-erence in a power meter is performed for thermocou-ple and diode power sensors. The reflection coeffi-cient of the power source is determined at the sametime.

AttenuationAttenuation calibrations are carried out by traceablevector network analyser measurements. Determina-tion of reflection coefficient by is included in the cali-bration. We calibrate fixed value attenuators as wellas step attenuators. The step attenuators can be con-trolled by using a GPIB bus, RS-232 connection ordirectly using the step attenuator controller Agilent11713A.

Reflection coefficientTraceable measurements of reflection coefficient areperformed using a vector network analyser. The im-pedance of the impedance standards used in themeasurements is determined at MIKES with accuratedimensional measurements. Dimensional measure-ment services for N-type airlines are offered for cus-tomers, also.

Figure 2. Measurement set-up for power sensors.

Figure 3. Measurement of reference step attenuator.

Table 1. Measurement ranges and uncertainties.

Quantity Measurementrange

Measurementfrequency range Uncertainty

Calibration coefficient of power sensors 1 mW 10 MHz – 18 GHz(1) 0.4 % – 1.1 % (k=2)(2)

Absolute power 1 mW 10 MHz – 18 GHz(1) 4 mW/W – 11 mW/W (k=2)Attenuation 0 dB – 80 dB 300 kHz – 6 GHz 0.02 dB – 0.17 dB (k=2)Attenuation 0 dB – 60 dB 6 GHz – 18 GHz 0.05 dB – 0.18 dB (k=2)Reflection coefficient (realand imaginary parts)

between –1 and 1 10 MHz – 18 GHz 0.013 – 0.024 (k=2.45) (3)

1) Frequencies for power calibrations: 10 MHz, 30 MHz, 50 MHz, 100 MHz, 300 MHz, 500 MHz, 1 GHz, 1,5 GHz,2 GHz – 18 GHz in 1 GHz steps.

2) Absolute value of reflection coefficient ≤ 0,083) A 95 % coverage for the complex uncertainty of a complex variable is obtained when k=2.45.






Chemistry

High voltage andhigh currentEsa-Pekka Suomalainen, Senior ScientistTel. +358 50 382 [email protected]

Jussi Havunen, ResearcherTel. +358 50 590 [email protected]


High voltage quantitiesThe importance of high voltage measurements hasbeen emphasized with the opening of electricity mar-kets. The quality of electricity, transmission lossesand the sale of electricity for industry and for privatehouseholds have become more important measuringand monitoring subjects. In addition to electricity,electronics and information industries, high voltageusers can be found, in almost every industrial sector.High voltage metrology at MIKES is internationally re-spected and provides services on traceability also atcustomers premises in Finland and globally.

TraceabilityThe high voltage measurements at MIKES are trace-able to capacitance, resistance and voltage, which inturn are based on quantum primary standards: quan-tum Hall resistance standard and Josephson voltagestandard. We have performed well and also acted asa coordinator in international comparisons in highvoltage metrology. As an example of this is the coor-dination of broad European and worldwide compari-sons of lightning impulse voltage measuring systems.








KemiaHigh voltage and high current


Calibration servicesMIKES offers calibration services for almost all highvoltage quantities and measuring systems up to 200kV voltage. The range of alternating current calibra-tions extends to 6 kA. The measuring range for pulsequantities covers a voltage range from millivolts up tomegavolts and currents up to tens of kiloamperes.Our expert services cover different aspects of calibra-tion of measuring systems. If wanted, we evaluatecustomer’s measuring systems and modify them tobe more accurate and stable if needed. In future, ourarea of qualification will be extended to calibrationsrelated to measurements on the quality of electricity.

The best calibration uncertain y is achieved, whencalibrations are performed in a laboratory at MIKESbut calibrations can be carried out at customer’spremises, also. Measuring systems can be calibratedon-site when the voltage level, the size of the system,grounding conditions or proximity effects necessitateit.

Calibration subjectsDevices that we calibrate include.

· voltage dividers· voltage and current transformers· measuring probes, voltage and current sensors

and current shunts· high voltage inductors and capacitors· transient recorders, peak voltage meters· surge-, EFT- and ESD- test devices· voltage testers· pulse calibrators· partial discharge calibrators

Table 1. Calibration services of high voltage.

Quantity Measurement range Uncertainty (k=2)

Direct current 1 kV – 1000 kV 0.0005 – 0.01 %Alternating voltage, voltage ratio 1 kV – 200 kV 0.002 – 0.01 %

– angle error 0 – 100 mrad 0.02 mrad

Alternating current, current ratio 1 A – 6 kA 0.0025 – 0.02 %

– angle error 0 – 100 mrad 0.2 – 0.4 mrad

Capacitance 1 – 100 kV / 10 pF – 200 µF 0.002 – 0.05 %– loss coefficient tan δ 1.10–5 – 2 1 % (1.10–5 abs)Inductance / losses 1 µH – 10 H 0.03 % / 0.2 mradLightning impulse 50 mV – 400 kV 0.1 – 0.5 %Switching impulse 1 V – 200 kV 0.1 – 0.2 %Other voltage impulses (e.g. surge) 1 V – 400 kV 0.1 – 0.5 %Current impulses 1 A – 10 kA 3 %ESD-pulse 1 A – 50 A 5 %Time parameters of pulses 0.7 ns – 100 ms 0.5 – 5 %Apparent charge of a pulse (partial discharge) 1 pC – 1 nC 2 % (0,2 pC abs)






Chemistry

Acoustic calibrationsKari Ojasalo, ResearcherTel. +358 50 410 [email protected]

Jussi Hämäläinen, ResearcherTel. +358 50 410 [email protected]


The need of accurate acoustic measurements isgrowing for instance due to regulations and legisla-tions concerning noise emissions and exposure to vi-brations. A good measurement accuracy requires, inaddition to high-quality measurement devices, regu-lar and traceable calibrations. In Finland, MIKES isresponsible for the traceability of the acoustic quanti-ties: sound pressure and acceleration.

Sound pressure is transformed into an electrical sig-nal by using accurate condenser microphones,whose primary calibration equipment is in use atMIKES. Sound level calibrators are calibrated usingthese condenser microphones. The traceability chainof sound pressure level starts from the calibration oflaboratory grade microphones by using a so-calledreciprocity calibration system. This calibration givesthe voltage-pressure sensitivities of the microphones.The method is described in the standard IEC 61094-2 (1992-03) and it is in use in several other nationalmetrology institutes.

A vibration transducer produces a signal, typically avoltage or a charge, which is proportional to the ac-celeration of mechanical motion. Therefore, in the cal-ibration of a vibration transducer, the sensitivity (typi-cally mV/(m/s2) or pC/(m/s2) of the sensor is deter-mined as a function of frequency. MIKES calibratesvibration transducers by comparing their readings toa known vibration produced with a vibration exciter.The real amplitude of acceleration and frequency issimultaneously measured by using a reference sen-sor. The method is described in the standard ISO16063-21:2003.

Figure 1. A reciprocity calibra-tion of microphones is startingin the soundproof laboratory atMIKES.








KemiaAcoustic calibrations


Calibration servicesMicrophonesWe calibrate ½ (LS2P) and 1 (LS1P) inch condensermicrophones described in the standard IEC 61094-1(Table 1). The calibration method depends on the ac-curacy required by the customer. The smallest cali-bration uncertainties can be achieved by using thereciprocity method. In many cases, a comparison witha reference microphone by a sound level calibrator isadequate.

Table 1. Uncertainties of calibration for microphones.

Type ofmicrophone

Frequency[kHz]

Uncertainty[dB]

LS 1

0.0315 0.060.063 ... 2 0.044 0.055 0.068 0.0810 0.10

LS 2

0.0315 0.080.063 0.060.125 ... 8 0.0510 0.0612.5 0.0816 0.1020 0.14

Sound level calibrators

Sound level calibrators and pistonphones are themost common devices calibrated at MIKES acousticslaboratory. We calibrate the sound pressure levels atfixed frequency points. At the same time, the distor-tion and frequency of the sound source is measured.

Vibration transducers and loggers

We calibrate vibration transducers, loggers and vibra-tion measurement devices in the frequency range1 Hz – 10 kHz. Typical nominal acceleration is10 m/s2. The calibration gives the magnitude and thephase of the sensitivity of the vibration transducer.The uncertainty of the calibration depends on thetransducer under calibration. Typical uncertainties forthe magnitude are 1–3 % and for the phase 1–2° de-pending on the frequency (Figure 2).

Figure 2: The measurement ranges and uncertainties ofcalibration of vibration transducers.

Table 2. Calibration ranges and uncertainties for sound level calibrators. The type of the measurement.

Type of calibrator Frequency (Hz) Sound level [dB re 20 µPa] Uncertainty [dB]

Single-frequency 125 – 1000 70 – 130 0.08

Multi-frequency31.5 94 – 114 0.15

63 – 4000 94 – 114 0.158000 – 12500 94 – 114 0.15






Chemistry

Calibration of time, timeinterval and frequencyIlkka Iisakka, ResearcherTel. +358 50 410 [email protected]

Anders Wallin, Senior ScientistTel. +358 50 415 [email protected]


Measurements of frequency and time interval areneeded in various direct and indirect measurements,e.g., in telecommunication; therefore, precise andtraceable frequency and time interval measurementsare important nationally. The importance of absolutetime is increasing, too (e.g. time stamps).

MIKES is responsible for the traceability of time, timeinterval, and frequency in Finland. MIKES time labor-atory maintains the official time in Finland with an un-certainty of 10 ns in relation to the coordinated univer-sal time (UTC) and national frequency with a 1•10–13

relative uncertainty. The reference standards for timeand frequency are one caesium atomic clock, four hy-drogen masers and several GPS receivers. Finlandparticipates in maintaining of the UTC with its five ref-erence standards through GPS based time compari-son.

Figure 1. The traceability of time and fre-quency is based on hydrogen masers (inthe figure left) and on caesium atomicclocks, which are located in enclosureshaving with a special climate control.








KemiaCalibration of time, time interval and frequency


Calibration servicesWe calibrate e.g. GPS receivers (frequency), oscilla-tors, time interval counters, stopwatches, strobo-scopes, and optical tachometers. The frequencyrange is 1 mHz to 5 GHz. We make time intervalmeasurements according to customer’s need, with alower limit of approximately one nanosecond. Fur-thermore, MIKES has a transmitter for time code andprecise 25 MHz frequency for those near the Helsinkimetropolitan area who need precise time and fre-quency.

In addition to calibration, we carry out special assign-ments related to time and frequency measurementsand participate in research and development collabo-ration projects in this field.

NTP - network time serviceComputer clocks can be synchronised with the na-tional time in Finland maintained by MIKES by usingNetwork Time Protocol, NTP. The achievable uncer-tainty depends on network connections but it isaround one millisecond at its best. MIKES maintainsNTP servers subject to charge for institutions andcompanies. We have four servers of the highest level(stratum-1): two of them are synchronised directly toMIKES atomic clocks and two to GPS receivers.Moreover, we control two public NTP servers that arelocked to MIKES servers. These servers are availablefree of charge for public use. Figure 3. Stabilities of various frequency standards as a

function of integration time.





Optics Length and ge-ometry

Chemistry

Optical quantitiesFarshid Manoocheri, Dr,Tel. +358 9 470 22337,[email protected]

Petri Kärhä, Dr,Tel. +358 9 470 [email protected]

Metrology Research Institute,Otakaari 5A, FI-02150 Espoohttp://metrology.tkk.fi

MIKES-Aalto MetrologyResearch InstituteMetrology Research Institute (MIKES-Aalto Mittaus-tekniikka) is a joint laboratory of Aalto University andMIKES. It is the national standards laboratory of opti-cal quantities in Finland. The laboratory is a researchand education unit belonging to the Department ofSignal Processing and Acoustics at the Aalto Univer-sity. The laboratory carries out basic research on LEDmeasurements, temperature measurements, opticalproperties of materials, measurement electronics andon various measurement methods of photometry andradiometry. In addition to calibration services, the la-boratory offers expert services and educates DiplomaEngineers (M. Sc.) and Doctors of Technology for de-manding professional tasks in academy and industry.

Research activitiesResearch activities and assignments of a nationalstandards laboratory require continuous internationalcooperation. International comparisons have an es-sential role in creating traceability chains and verify-ing measurement uncertainties. The laboratory hasan active role in, e.g. EURAMET, CCPR, and CIE or-ganisations and takes actively part in the EU researchprograms.

Figure 1. Integrating sphere isused as a light source in cali-bration of luminance and radi-ance. The sphere has a uni-form spatial distribution of theout coming light intensity.



http://metrology.tkk.fi/





KemiaOptical quantities


Calibration servicesMetrology Research Institute offers calibration ser-vices to the optical quantities listed in the followingtable. All measurements are traceable to nationaland international measurement standards. Meas-urement uncertainties are verified by internationalcomparison measurements. We are pleased to givefurther information, e.g. on the contents of calibra-tion services and on the measurement uncertainty indifferent measurement and wavelength ranges.

Calibration objectslnstruments that we calibrate include among others:

• illuminance meters• standard lamps• radiance and luminance meters• laser power meters• optical filters• reflectance references• UV-meters• fluorescent samples.

Figure 2. The spectral irradiance of a lamp is measured bypositioning the lamp at an accurately determined distancefrom a radiometer, whose spectral responsivity and surfacearea are known.

Figure 3. Part of the calibrations can be car-ried out as field calibrations at customer’s la-boratory premises. A filter radiometer devel-oped in our laboratory for calibration of spec-tral irradiance or illuminance of standardlamps is shown in the figure.

Quantity Measurement range Wavelength range Uncertainty (k=2)Luminous intensity 1 – 10 000 cd – 0.5 %IlluminanceIlluminance responsivity 0.1 – 5 000 lx – 0.5 % – 0.7 %

LuminanceLuminance responsivity 1 – 40 000 cd/m2 – 0.8 % – 1.0 %

Luminous flux 10 – 10 000 lm – 1.0 %

Spectral irradiance 100 μW m–2 nm–1

– 500 W m–2 nm–1 290 – 900 nm 0.8 % – 2.9 %

Spectral radiance 100 μW m–2 sr –1 nm–1

– 1 W m–2 sr –1 nm–1 360 – 830 nm 1.4 % – 4.2 %

Colour coordinates (x, y) 0,1 – 0,9 – 0.0005Colour temperature 2800 – 3250 K – 5 KOptical power 0.1 – 0.5 mW 325 – 920 nm 0.05 % – 1.0 %

Spectral responsivity 0.01 – 20 μW0.05 – 5.0 mW

380 – 1700 nm250 – 380 nm

0.5 % – 4.0 %2.0 % – 5.0 %

Transmittance 0.0001 – 1 250 – 1700 nm 0.2 % – 5.0 %Absorbance 0 – 4 250 – 1700 nm 0.0009 – 0.022Reflectance (5° – 85°) 0.01 – 1 250 – 1000 nm 1.0 % – 5.0 %Diffuse reflectance factor 0.1 – 1 360 – 830 nm 0.4 % – 1.0 %Fibre optic power 1 nW – 200 mW 1310 – 1550 nm 1.2 % – 2.0 %






Chemistry

Quantitative Microscopy –Atomic Force MicroscopeVirpi Korpelainen, Senior ScientistTel. +358 50 410 [email protected]


Development and research in nanotechnology has in-creased the need for accurate measurements in re-search institutes and industry. Different kinds of Scan-ning Probe Microscope (SPM) measurements arecommonly used in many institutes and companies. Inorder to guarantee accurate and reliable dimensionalmeasurements at nanometre range, MIKES has atraceably calibrated Atomic Force Microscope (AFM).Thus, MIKES can provide customers with traceablemeasurements also at nanometre range.

MIKES provides accurate AFM measurement ser-vices to match the needs of customers. In addition, wecalibrate SPM transfer standards.

Figure 1. Alignment of laserbeams for interferometriccalibration of y-axis of theAFM.







KemiaQuantitative Microscopy – Atomic Force Microscope


MIKES has a PSIA XE-100 AFM, which is calibratedinterferometrically and with grating calibrated by la-ser diffraction at MIKES. The AFM is traceable tothe definition of the metre. The xy-movements of theAFM are mechanically separated from the z-move-ments. This increases the linearity of the move-ments, decreases out of plane movements andeliminates crosstalk. The structure of the device al-lows rather large samples to be measured. Meas-urements can also be done using the most usualmeasurement modes: contact, non-contact, tappingand lateral force. The measurement results can beanalysed using SPIP software 1.

Scale errors of uncalibrated SPMs typically rangefrom 2 % to 20 %. In addition, measurement errorsmay cause distortions in the measured figure, whichmight be difficult to detect from the figure. Therefore,the device has to be calibrated. New, more advan-ced SPMs have increased measurement precision,but the development does not remove need for cal-ibration. Especially in all quantitative form measure-ments, the measurements should be traceable tothe definition of the metre. Usually SPMs are cali-brated by using calibrated transfer standards.1 The Scanning Probe Image Processor SPIPTM

http://www.imagemet.com

Property DataSample size <100 mm × 100 mmSample thickness <20 mmSample mass <500 gMeasurement range (xy) 100 µm × 100 µmMeasurement range (z) 12 µm

Resolution (xy) 0.15 nm0.02 nm (low voltage mode*)

Resolution (z) 0.05 nm0.01 nm (low voltage mode*)

Uncertainty (k=2),x and y directions Q [3; 2 L/µm] nm

Uncertainty (k=2),z direction

Q [3; 2 L/µm] nm

Q [x; y] = (x2 + y2)1/2

Figure 2. 2-D grid standard.

Figure 3. AFM image of Seeman tiletype DNA nano-origami structures.

http://www.imagemet.com/






Chemistry

Characterizationof nanoparticlesVirpi Korpelainen, Senior ScientistTel. +358 50 410 [email protected]


Nanoparticles are widely used in many applications.Accurate characterization of the nanoparticles is im-portant in research, production and applications inseveral fields including industry, health, safety and re-lated regulation. At VTT MIKES metrology, the parti-cles can be characterized using two different meth-ods: Dynamic Light Scattering (DLS) and atomic forcemicroscopy (AFM). The measurements are traceableto the definition of the metre via MIKES interferomet-rically traceable metrological atomic force microscope(IT-MAFM). Both methods have advantages and lim-itations. DLS is fast method and the results are statis-tically representative. In DSL measurements, even asmall number of large particles can prevent detectionof small particles. AFM can be used to measure bothsize and shape of single particles. The disadvantageof AFM measurements is that only limited number ofparticles can be measured which leads to poor statis-tics. Tip sample interaction is important especiallywhen measuring small particles. In addition, samplepreparation might be challenging.

Figure 1. AFM image of 100 nm nanoparticles.

Figure 2. DLS measurements.

Table 1. VTT MIKES metrology has two instruments suita-ble for nanoparticle measurements.

Instrument Zetasizer Nano PSiA XE-100

Measurement method DLS AFM

Measurands Size distributionZeta potential

SizeShape

Measurement range 0.3 nm – 10 µm 5 nm – 5 µmMeasurementuncertainty 2 % from 1 nm







KemiaCharacterization of nanoparticles


Zetasizer NanoDynamic Light Scattering is used to measure particleand molecule sizes. This technique measures the dif-fusion of particles moving under Brownian motion,and converts this to size and a size distribution usingthe Stokes-Einstein relationship.

Laser Doppler Micro-electrophoresis is used to meas-ure zeta potential. An electric field is applied to a so-lution of molecules or a dispersion of particles, whichthen move with a velocity related to their zeta poten-tial.

Services for nanoparticlecharacterization

• Nanoparticle size and shape measurementsusing AFM

• Nanoparticle size distribution in solution usingDLS

• Nanoparticle surface charge (Zeta-potential)measurements in solution

Atomic force microscopy (AFM)An AFM uses a cantilever with a very sharp tip to scanover a sample surface. As the tip approaches the sur-face, the close-range, attractive force between thesurface and the tip cause the cantilever to deflect to-wards the surface. However, as the cantilever isbrought even closer to the surface, such that the tipmakes contact with it, increasingly repulsive forcetakes over and causes the cantilever to deflect awayfrom the surface.

In AFM images the topography of a sample surfaceby scanning the cantilever over a region of interest.The raised and lowered features on the sample sur-face influence the deflection of the cantilever, whichis monitored by a position-sensitive photo diode(PSPD). By using a feedback loop to control theheight of the tip above the surface the AFM can gen-erate an accurate topographic map of the surface fea-tures.

Figure 3. DLS results of ~100 nm nanoparticles.






Chemistry

Calibration of laserinterferometersJeremias Seppä, Senior ScientistTel. +358 50 410 [email protected]

Veli-Pekka Esala, Senior ScientistTel. +358 40 866 [email protected]


Laser interferometers together with gauge blocks arethe most important measurement standards in mod-ern length metrology. At 1980s a common under-standing was that laser interferometers are accurateand hence do not need any calibration. However,ever-increasing demand for accuracy and long expe-rience on usage of laser interferometers have shownthat it is necessary to calibrate laser interferometers,also. At MIKES, we have traceable procedures to cal-ibrate laser interferometers. The calibration of laserinterferometers improves their reliability and accuracyessentially.

Figure 1. Functional testing of a laser interferometer.

Figure 2. An iodine-sta-bile HeNe-laser used forthe practical realisationof the metre.








KemiaCalibration of laser interferometers


Calibration procedureCalibration of laser frequency

The vacuum wavelength of lasers used in laser inter-ferometers is calibrated using iodine-stabilised lasers.Traceability to the definition of the metre is guaranteedas frequencies (vacuum wavelength) of the iodine-sta-bilised lasers are determined by an optical frequencycomb referenced to an atomic clock.

MIKES maintains the following lasers that are lockedto iodine absorption lines according to internationalrecommendations: He-Ne lasers at wavelengths: 633nm (Figure 2) and 543.5 nm and a Nd:YAG-laser at532 nm. These laser have a relative frequency uncer-tainty better than 10-10 (expanded uncertainty, k=2).

The frequency of the laser under calibration is com-pared to the frequency of an iodine-stabilized laser.The calibration includes a long-term frequency (vac-uum wavelength) calibration and repeatability meas-urements. Moreover, the frequency difference of thehorizontally and vertically polarised lights is deter-mined and the separation of the polarisation planes in-spected. Together these measurements provide goodindication of the frequency stability of the laser undercalibration. Lasers that operate at wavelengths notreachable by iodine-stabilized lasers can be calibratedusing a frequency comb.

Figure 3. Errors in environmental sensors can have remark-able effects on the readings of a laser interferometer.

Table 1. Uncertainty of calibration.

Quantity Measuring range Uncertainty (k=2)

Wavelength 633 nm; 543.5 nm;532 nm

~10–9 (relative)

Air pressure 970…1050 hPa(730 … 790 mmHg)

40 Pa

Air temperature 17…25 °C 0.10 °CMaterialtemperature

15…25 °C 0.050 °C

Calibration of functional testing ofenvironmental sensors

In addition to laser vacuum wavelength calibration,the environmental sensors are calibrated and theiroperation tested. These measurements are neces-sary to achieve the naturally good measurement ac-curacy of a laser interferometer. Especially, by cali-brating the environmental sensors order of magni-tude better measurement accuracy can be achievedfor a laser interferometer.

The calibration of environmental sensors includesthe calibration of air temperature sensors, atmos-pheric pressure sensors and material temperaturesensors. The functional testing is performed in atemperature-stabilised laboratory room by measur-ing the locations of a moving carriage equipped witha retroreflector with the laser interferometer undercalibration and with a reference laser interferometer(Figure 1). In these measurements, both laserbeams travel through the same optical componentsand data is collected with and without the environ-mental sensors operating. In addition, the anglescale is tested using a reference laser. If necessary,the quality of the optical components is tested witha flatness interferometer.

If the readings of the environmental sensors deviateremarkably from readings of the reference instru-ments, they should be adjusted. By adjusting, theaccuracy of the laser interferometer can easily beimproved (Figure 3), e.g., the adjustment is relativelyeasy to perform in Agilent laser interferometers.

TraceablityThe frequencies of the iodine-stabilised lasers thatare the national measurement standards of lengthare determined using an optical frequency comb ref-erenced to MIKES atomic clocks. The instrumentsused in the calibration of environmental sensors arecalibrated in the corresponding national standardslaboratories. Thus, the measurements are traceableto the corresponding definitions of the units.






Chemistry

Interferometric calibra-tion of gauge blocksPasi Laukkanen, Research EngineerTel. +358 50 382 [email protected]

Antti Lassila, Senior ScientistTel. +358 40 767 [email protected]


Calibration of gauge blocksGauge blocks are the most important measurementstandards of length in industry. Interferometric meas-urement of gauge blocks provides an absolute cali-bration method. By using interferometers, the practi-cal realisation of the metre is transferred to a gaugeblock via the calibrated wavelength of the frequency-stabilised laser used in the interferometer. Gaugeblocks calibrated by comparison must be traceable togauge blocks calibrated by interferometry. The lengthof a gauge block is defined in an ISO standard as thedistance from the centre of the gauge face to an aux-iliary reference plane wrung to the other end of thegauge block at 20 °C temperature and at 1013.25 hPabarometric pressure. Gauge block sets calibrated byinterferometry give a lower uncertainty for mechanicalcalibrations e.g. in accredited calibration laboratories.

Interferometers at MIKESMIKES have gauge block interferometers for short(0…300 mm) and for long (100…1000 mm) gaugeblocks and end standards. The interferometers are lo-cated in a laboratory room having well stabilised en-vironmental conditions and they are equipped withtemperature, humidity and pressure sensors. Low un-certainties for refractive index of air and for thermalexpansion compensation can be achieved with a pre-cise control and monitoring of the environmental con-ditions. Difference in surface roughness between thegauge block face and the reference plane is meas-ured and corrected for in results. The parallelism andflatness of the surfaces can be measured, also.

The MIKES PSIGB interferometer for short gaugeblocks (Fig. 1) uses stabilised He-Ne lasers at 633 nmand 543.5 nm. The interferometer is equipped with alarge wringing bed, which enables fast and auto-mated calibration of even 14 gauge blocks in se-quence. In the Tesa interferometer, the gauge blocksare positioned vertically.

Figure 1. Tesa-NPL gauge block interferometer.

The long gauge block interferometer (Fig. 2) utiliseswhite light and 633-nm laser light interference pat-terns. By using white light, beforehand knowledge ofthe length of the end standard is not required. Theend standards and gauge blocks are positioned hori-zontally and supported at the Bessel points in such away that the weight of the reference plane is compen-sated for.








KemiaInterferometric calibration of gauge blocks


TraceabilityThe regular calibration of length standards and lengthmeasuring equipment is a necessary part of meas-urement quality control. Traceable calibrations andknowledge on the measurement uncertainty are basicdemands for good and constant quality. The tracea-bility to gauge block calibrations is achieved by cali-brating the wavelengths of lasers used in the interfer-ometers against national measurement standards oflength, iodine-stabilised He-Ne lasers. Measuring de-vices for temperature, humidity and pressure used inthe interferometers are calibrated in correspondingMIKES laboratories. The reliability of calibrations areverified by taking regularly part in international com-parisons.

Calibration servicesGauge block interferometers can be used to measureeven other artefacts whose surfaces are flat andsmooth enough; for instance to determine the thermalexpansion coefficient of ceramic sealings and tomeasure the air gap between two parallel glassplates. Interferometric calibration sets also demandsfor gauge blocks: their end surfaces must be parallel,flat and without scratches. MIKES calibrates gaugeblocks of grades K (00) and 0 and end standards, e.g.quartz metres, according to the following table.

Figure 2. MIKES length bar interferometer for calibration oflong gauge blocks.

Table 1. Calibration subjects and measurement uncertainties.

Device Measurement range Uncertainty (k=2)

Gauge blocks, small 0.5 mm ... 300 mm Q[20; 0.3L] nm

Gauge blocks, long 100 mm ... 1000 mm Q[30; 0.11L] nm

Quartz meters 1000 mm 72 nm






Chemistry

Calibration of gauge blocksby mechanical comparisonArttu Ollikainen, Research AssistantTel. +358 50 395 [email protected]



Mechanical comparison measurement is the mostcommon way to determine the length of a gaugeblock. In this method, the length of the gauge blockunder calibration is compared to the length of a cali-brated gauge block with same nominal length by us-ing a specific comparator, Figure 1.

Gauge block measurementComparison measurements of gauge blocks thathave the same nominal length and that are of thesame material are simple, reliable, fast and inexpen-sive. The method is also applicable to gauge blockswhose surfaces have been worn-out in use. MIKEScalibrates steel, hard metal, and ceramic gaugeblocks in lengths 0.1 ... 1000 mm (Table 1). In calibra-tion, we check the flatness of the surfaces and re-move splatters that could prevent reliable use of thegauge blocks. A regular inspection of gauge blocksprevents a possible damage to affect the whole set.The use of uncalibrated gauge blocks in productionquality control and in calibration of measurementequipment causes extra risks and costs

Figure 1. The sensor of the gauge block comparator identi-fies the location of the surface by using 0.6 Nm measure-ment force.

Table 1. Calibration of gauge blocks by mechanical comparison.

Measurement device Measurement range Uncertainty

Tesa gauge block comparator 0.1 mm …100 mm Q[0.050; 0.00087L] µm

MIKES comparator for long gauge blocks 100 mm …1000 mm Q[0.20; 0.00087L] µm

L is the nominal length in millimetres








KemiaCalibration of gauge blocks by mechanical comparison


TraceabilityThe reference gauge blocks used in mechanical com-parison measurements are regularly calibrated usingMIKES gauge block interferometers. The wavelengthsof lasers used in these interferometers are calibratedby national measurement standard of length, iodine-stabilised He-Ne lasers

Table 2. Accuracy grades of ISO 3650:1998 standard.

Nominal length rangemm

Calibration gradeK

mm

Grade0

mm

Grade1

mm

Grade2

mmLowerlength

Upperlength ±te tv ±te tv ±te tv ±te tv

0.5 10 0.20 0.05 0.12 0.10 0.20 0.16 0.45 0.30

10 25 0.30 0.05 0.14 0.10 0.30 0.16 0.60 0.30

25 50 0.40 0.06 0.20 0.10 0.40 0.18 0.80 0.30

50 75 0.50 0.06 0.25 0.12 0.50 0.18 1.00 0.35

75 100 0.60 0.07 0.30 0.12 0.60 0.20 1.20 0.35

100 150 0.80 0.08 0.40 0.14 0.80 0.20 1.60 0.40

150 200 1.00 0.09 0.50 0.16 1.00 0.25 2.00 0.40

200 250 1.20 0.10 0.60 0.16 1.20 0.25 2.40 0.45

250 300 1.40 0.10 0.70 0.18 1.40 0.25 2.80 0.50

300 400 1.80 0.12 0.90 0.20 1.80 0.30 3.60 0.50

400 500 2.20 0.14 1.10 0.25 2.20 0.35 4.40 0.60

500 600 2.60 0.16 1.30 0.25 2.60 0.40 5.00 0.70

600 700 3.00 0.18 1.50 0.30 3.00 0.45 6.00 0.70

700 800 3.40 0.20 1.70 0.30 3.40 0.50 6.50 0.80

800 900 3.80 0.20 1.90 0.35 3.80 0.50 7.50 0.90

900 1000 4.20 0.25 2.00 0.40 4.20 0.60 8.00 1.00

Note: The calibration ISO grades 0, 1, and 2 correspond to accuracy classes A, B, and C in OIML standard no. 30, respectively

Abbreviations in the table 2:te = deviation of length from nominal lengthtv = variation in length






Chemistry

2D and 3D measurement ofform and surface roughnessBjörn Hemming, Senior ScientistTel. +358 50 773 [email protected]

Maksim Shpak, ResearcherTel. +358 50 415 [email protected]


The manufacturing tolerances of modern productsand the aim to high quality require the ability to meas-ure different form measurands of small artefacts hav-ing complicated shapes. Examples of such formmeasurands are straightness, parallelism, radius ofcurvature and surface roughness. MIKES measure-ment and calibration services using a computer con-trolled form and surface texture instrument providesone solution to these measurement problems.

Form mesurementThe form measurement instrument can detect formdeviations even as small as 0.6 nm. Examples of typ-ical form measurements are accurate measurementsof straightness, inner and outer determinations of ra-diation of curvatures and diverse dimensional meas-urements of small artefacts (Figure 1). These includedeterminations of grooves lengths and depths and in-ner and outer angle measurements. The most im-portant technical specifications of the Taylor HobsonForm Talysurf instrument are gathered in table 1.

Figure 1. Straightness measurement on a cylindrical sur-face.








Kemia2D- and 3D- measurement of form and surface roughness


Surface roughnessmeasuremensIn addition to calibration of surface roughness stand-ards, the surface texture instrument at MIKES is usedfor tasks related to quality control and product devel-opment. The surface roughness measurements atMIKES are based on the following standards: ISO5436-1 and ISO 4287.

Measurement subjects• traceable calibration of surface roughness stand-

ards• diverse measurements in development of pros-

thesis in health care industry• measurement of tribological samples• profile measurements of blades of excavation

machinery• geometrical measurements in product develop-

ment and quality control of electronic components• product development and quality control meas-

urements of metal packings and components inhydraulics and pneumatics.

TraceabilityTraceability to the form measurement instrumentcomes from interferometrically calibrated gaugeblocks, a line scale, an optical flat and a sphere.

Figure 2. Measurement of sideline.

Table 1. The most important technical specifications of the Taylor Hobson Form Talysurf instrument.

Property Information

Instrument and operational principle Taylor Hobson Form Talysurf Ser. 2, Type 112/2815-02, inductive

Measurement tips Diamond tip, radius 0.002 mm,Spherical sapphire tip, radius 0.397 mm.

Measurement forces 1.0 mN (using diamond tip),15–20 mN (using sapphire tip)

Surface texture parameters R3y, R3z, Ra, Rc, Rda, Rdc, Rdq, RHSC, Rku, Rln, RLo, Rlq, Rmr,Rmr(c), Rp, RPc, Rq, RS, Rsk, RSm, Rt , Rv, RVo, Rz, Rz(JIS).In addition, a series of waviness parameters.

Longest measurement length 120 mmMaximum height of artefact 700 mm, maximum width in 3D measurement is 50 mmLargest allowed deviation 28 mm (120 mm arm)Measurement speed 1 mm/sResolution 0.0006 µmLowest uncertainty Q[10; 70P] nm, where P is the deviation from flatness in micrometers






Chemistry

Optical measurement ofsurface microstructuresVille Heikkinen, ResearcherTel. +358 50 415 [email protected]

Björn Hemming, Senior ScientistTel. +358 50 773 [email protected]


Micro to millimetre range structures can be measuredat MIKES using scanning white light interference mi-croscope (SWLI).

The SWLI has sub-nm vertical and µm level horizon-tal resolution. It can measure square mm areas in asingle scan. Benefit of SWLI compared to other in-struments with similar vertical resolution include largemeasurement area ability to measure high steps andability to measure overlapping surfaces inside oftransparent structures. See table 1 for more proper-ties of the instrument.

Real life measurement uncertainty is case dependentand depends on measurement environment, proper-ties of instrument and properties of measured sam-ple. At MIKES, we take care that the sample is clean,sample temperature is known and the sample is wellattached and properly aligned. Measurements aredone traceably under consistent conditions and re-sults are well documented.

Examples of potentialmeasurement objects:

• Bearings, contact surfaces, surface topographyand wear

• Semiconductors and MEMS• Medical instruments and implants• Optical components• Precision machined components

Figure 1. Bruker ContourGT-K scanning white light inter-ferometer.

We do different measurementsusing the SWLI

• Different type of objectso surface shape measurementso x,y,z dimensions of details on a surfaceo film thickness measurement, layer separationo surface roughness (2D and 3D ISO rough-

ness parameters), flatness, deviation from ashape

• Calibration of different instruments• Calibration of reference artefacts

o step heights, air gap artefacts, film thicknessartefacts








KemiaOptical measurements of surface microstructures


Optimal measurement conditionSWLI is in underground measurement room with (20± 0.1) °C temperature. Most heat sources in the roomhave been eliminated by venting warm air out.

TraceabilitySWLI is traceable to the SI-metre through MIKES’sown transfer standards such as step height stand-ards, gauge blocks and laser interferometer.

Table 1. Properties of SWLIProperty InformationOptical x-y resolution 3.8 – 0.7 µmPixel size 7.2 – 0.2 µmVertical resolution < 0.1 nmStep height measurement:

• repeatability < 0.1 %• accuracy < 0.75 %

Sample reflectivity: 0.05 % – 100 %Maximum surface tilt (smooth samples): 3° (2.5× objective), 18.9° (20× objective)Magnifications 2.5× and 20× objectives, 0.55×, 1× and 2× zoom lensesMeasurement area (X × Y × Z mm3):

smallest magnificationMeasurement area (X × Y × Z mm3):3.5 × 4.6 × 3.5

largest magnification 0.4 × 0.6 × 3.5Measurement area in pixels 640 × 480Programs Vision64 Analysis Software, MountainsMap, MatLab

Maximum size of measured object 10 cm high × 20 cm wide, one dimension can be longer

Ability to measure overlapping surfaces 2 surfaces in single measurementMaximum depth is dependent on refractive index, geometry andmagnification, e.g. it is possible to measure through 0.3 mm thickglass. 7 mm maximum depth limited by working distance.

Figure 2. Measurement of machined aluminium surface

Figure 3. Measurement of a groove on a glass surface.






Chemistry

Calibration oftachymetersJarkko Unkuri, ResearcherTel. +358 40 410 [email protected]

Antti Lassila, Senior ScientistTel. +358 40 767 [email protected]


MIKES calibrates angle and distance measurements functions of tacheometers.

Calibration of a distance metrein a 30-metre measuring railReadings from a distance meter of a tachymeter iscompared to readings from a laser interferometer ofthe 30-metre measuring rail. The measurement axisof the tachymeter and the laser interferometer arealigned to be parallel. The reading of the interferome-ter is set to zero at the beginning of the measuringrail. The observed reading of the distance meter atthe zero point of the interferometer is subtracted from

the readings of the distance meter. In the calibrationcertificate, the deviations from the references dis-tances and the expanded measurement uncertaintyare given for each target point. The target point canbe a prism, a reflector tape or a target plate. Themeasurement uncertainty depends on the scatter ofthe measurement results and is typically between0.05 – 0.25 mm for accurate distance meters.

Figure 1. MIKES 30-mmeasuring rail.








KemiaCalibration of tachymeters


Calibration of angle meas-urements by using a rotarytable and collimation tubesThe vertical and horizontal scales of a tachymeter arecalibrated by using an Eimeldingen rotary table as areference. The rotary table is calibrated using poly-gons and collimation tubes.

In the calibration of the horizontal scale, the tachym-eter is placed to the rotary table in such a way that thevertical axis is aligned to the rotational axis of the ta-ble (Figure 2). The table is rotated 360° in 30° stepsand at each step the reading of the tachymeter thathas been targeted to the collimation tube are rec-orded.

The vertical scale of the tachymeter is calibrated inthe same way but now the rotary table is turned tovertical position by using optomechanics that havebeen designed especially for this purpose. Figure 2. Calibration of the horizontal plane of a tachymeter

in an Eimeldingen rotary table with a collimation tube as atarget point.

Contents of tacheometer calibration Typical measurement uncertainty

Calibration of length scale

deviation from referenceprecision target 0.15 mmspherical target 0.15 mmreflector tape 0.20 mmwithout target

calibration of angle scale

scale error of the vertical circle 2" – 3"scale error of the horizontal circle 1" – 2"tilting axis error 1" – 2"index error of the vertical circle 0.5" – 1.5"line-of-sight error 0.5" – 1.5"crosshair alignment and perpendicularityinfluence of focussingchecking the readings of the environmental sensorsdivergence test of automatic targeting






Chemistry

Angle and perpendicu-larity measurementsAsko Rantanen, Senior ResearchTechnician, Tel. +358 400 925 [email protected]



Angle measurements are important in all mechanicalengineering and construction industry. The signifi-cance of angle measurements is increased also in di-mensional measurements when dimensions in-crease. Perpendicularity that is related to right anglesand square blocks is an important special case of an-gle measurement.

The SI-unit for angle is radian (rad) but depending onthe branch of industry and the measurement subjectother units are commonly used. In mechanical engi-neering angles are normally expressed in degrees [°],minutes ['] and seconds ["], in geodesy the most com-monly used unit is gon [gon] (also referred to asgrade). In earth-moving work and for small angles theunit [mm/m] is generally used. The diverse group ofunits for angle include also the following ways to ex-press the angle: percent [%] and length ratios.

Perpendicularity according to the ISO1101 standard:

• As a result the width t of tolerance zone is given• One side is defined as the reference side and

only against this side the perpendicularity is de-termined.

Figure 1. Polygon attachedto a rotary table. Errors fromthe rotary table and the poly-hedron can be separated byperforming a measurementseries using a Moller WedelHPR autocollimator.








KemiaAngle and perpendicularity measurements


Instruments for measuring angleThe most typical objects of calibration in mechanicalworkshops are rotary tables of machine tools andmeasuring machines, universal bevel proctractors,angle blocks, and different kinds of spirit (bubble) lev-els. Typical angle measurement instruments used inmachine installation and in construction engineeringare e.g. electronic levels, theodolites, levelling instru-ments, tacheometers, laser interferometers, autocol-limators and polygons.

Figure 2. Calibration of the horizontal scale of a tacheome-ter using an Eimeldingen rotary table and an autocollimatoras a target point.

Measurement uncertaintyAll measurements are performed in a well-controlledlaboratory room at temperature +20 °C ± 0.1 °C. Theachievable measurement uncertainty depends criti-cally on the artefact under calibration and its proper-ties (e.g. form errors and surface roughness)

Figure 3. Calibration of a granite square using a measur-ing machine developed at MIKES.

Table 1. Examples of lowest uncertainties for angle measurement instruments.

Instrument Measuringrange

Measurementuncertainty (k=2) Limitations

Optical polygons 0° – 360° 0.2"

Rotary index table 0° – 360° 0.5" indexing angle n x 15°

Rotary table 0° – 360° 0.2"

Autocollimator 0° – 1° 0.02"

Electronic level 0° – 360° 0.2"

Theodolite 0° – 360° 0.2" instrument limits the vertical angle

Angle block 0° – 360° 0.2"

Steel or granite squares 90° 0.5" max. length 1 m

Cylinder square 90° 0.5" max. length 1 m

Optical right angle 90° 0.5"






Chemistry

Measurements of accurateinner and outer dimensionsPasi Laukkanen, Research EngineerTel. +358 50 382 [email protected]



Measurements using SIPlength measuring machinePrecise measurements of inner and outer diametersare performed using SIP length measuring machineeither by using its own scale or by referencing to astandard of equal length (Figure 2). In the measure-ment, a contact is made using a ceramic sphericalmeasuring probe, a flat tip or in inner measurementsa lever probe. If the measurement depth in innermeasurements is over 15 mm, special hook-shapedjaws are used. The measuring force can be tuned be-tween 0.3…11 N. By measuring with several differentforces, the deformations due to the measuring forcescan be eliminated from calculations and the resultgiven at so-called zero-force. This is essential whenthe reference and the artefact under calibration aremade of different materials or have different shapes.

The accuracy of the length scale in SIP length meas-uring machine can be improved by using a laser in-terferometer (5528A) and a separate readout pro-gram. Measurements are performed in a well-con-trolled laboratory room at temperature +20 °C ± 0.1°C. Different types of heat sources are eliminated byusing vent pipes, heat shields, and when necessarywith a separate laminar flow. In addition to the meas-urement length, the measurement uncertainty de-pends on the measured artefact (shape and surfacetexture), on measuring instrument, measurementconditions, and on the method used.

In addition to diameter measurements, the SIP lengthmeasuring machine is used for thread measurementsand tolerance comparisons. The inner threads aremeasured using spherical probes and in outer threadmeasurements, three-wire method is used.

Figure 1. Measurement usingSIP length measuring machine.








KemiaMeasurements of accurate inner and outer dimensions


Measurements supplement-ing diameter measurementsIn order to get a precise picture of the features of anaxially symmetrical artefact that is under measure-ment, one should also measure its roundness, sur-face roughness and straightness of sides using ap-propriate instruments.

TraceabilityMeasurements made using the SIP length measuringmachine are traceable to corresponding transferstandards that are calibrated at MIKES. The linearscale is calibrated using a laser interferometer, thereference gauge blocks are calibrated interferometri-cally, and the temperature sensors are calibrated intemperature baths against reference Pt25 thermo-couples.

Table 1. Measurement uncertainties achievable in diame-ter measurements.

Measurement artefact Measurement uncertainty(k=2)

Thread plug 0 – 550 mm Q[0.2; 0.87L] µm

Ring gauge 1 – 500 mm Q[0.2; 0.87L] µm

Sphere 0.2 mm … 200 mm Q[0.15; 0.7L] µm

L in metres

Figure 2. Mounting side by side the artefact under calibra-tion and the reference in a comparison measurement.

Figure 3. SIP 550M length measuring machine.






Chemistry

Coordinate measurementPasi Laukkanen, Research EngineerTel. +358 50 382 [email protected]



The coordinate measuring services at MIKES includemeasurements with an optical coordinate measuringmachine and with a high-accuracy industrial size con-tact probe coordinate measuring machine.

Contacting coordinatemeasurementThe basic properties of MIKES coordinate measuringmachine are accuracy, flexibility, speed, and auto-matic calculation of results.

The MIKES 3D coordinate measuring machine is aMitutoyo Legex 9106 with portal structure (Figure 1).Further information on this machine can be found inTable 1. The true measurement uncertainty is alwayscase-specific and depends on the environmental con-ditions, on the machine, and on the properties of thework piece. We pay special attention in our workingon surface cleanliness, temperature, mounting (Fig-ure 2), alignment, measuring system, and on the doc-umentation of results.

Figure 1. Mitutoyo Legex coordinate measuring machine.








KemiaCoordinate measurement


The coordinate measuring machine is used for:• custom measurements of 3D-workpieces

(figure 3) and difficult shapes– scanning– digitizing point clouds

• various calibration of measurement devices– rulers, surface plates, gauges, cones, squares

• calibration of transfer standards for coordinatemachines– step gauges, ball cubes.

Optimal measurementconditions undergroundThe coordinate measuring machine is located in alarge volume underground laboratory room held at(20 ± 0.2) °C constant temperature. Most of the heatsources in the laboratory are eliminated using ventpipes. Moreover, the room is equipped with a 1000-kg load lifter on rails and a lift with 4000 kg maximumload capacity can be used to haul the goods into thelaboratory.

TraceabilityIn commissioning, various laser and gauge blockmeasurement were carried out on the coordinatemeasuring machine. Furthermore, the machine isregularly calibrated using our own measurementstandards: step gauges, ball plates, and a laser inter-ferometer. The measurement uncertainty and tracea-bility are verified in each case separately using so-called substitute method, i.e. results are corrected us-ing the results of a calibrated standard.

Figure 3. A typical artefact that can be measured usinga coordinate measuring machine.

Figure 2. The proper mounting of work pieces is important.

Table 1. The main properties of the coordinate measuringmachine.

Property DataPerformance checked ac-cording to ISO 10360-2:• maximum error in

length measurements• maximum 3D contact

deviation• maximum error in scan-

ning measurement

MPEe = (0.35 + L /1000) µm,L = mmMPEP = 0.35 µm

MPEthp = 1.4 µm

Scales Mitutoyo Zerodur scales withfloating mounting, resolution0.01 μm.

Travelling length X-910 mm, Y-1010 mmand Z-610 mm

Contact probe Renishaw indexing headPH10MQ Renishaw SP25Mcontact and scanning probe

Software Mitutoyo COSMOS software• Geopak-Win geometry

program• Statpak-Win geostatistical

analysis for quality control• Scanpak-Win form

measurement• 3Dtol-Win/ MCAD300 com-

parison with CAD modelsand importing CAD data

Measuring force 0,03 N…0,09 NMax. workpiece mass 800 kgDiameter of probes 0.5 mm…30 mm






Chemistry

Optical coordinate meas-uring – vision measuringVille Byman, ResearcherTel. +358 50 386 [email protected]



The manufacturing tolerances of modern productsand the aim for high quality require ability to makeprecise measurement of dimensional measurands onsmall artefacts of complicated shapes. The use of vi-sion measuring machines and machine vision is wellestablished in non-contact high-precision measure-ment.

MIKES have a Mitutoyo Quickvision Hyper QV-350vision measuring machine (optical CMM or videomeasuring machine) that is equipped with a CCD-camera as well as with a contact probe. In non-con-tact optical measurements, the machine takes ad-vantage of the measurement point location detectedby the CCD camera and location information from theprecise scales attached to mechanical guides.

Figure 1. The artefact under study can be illuminated withring, coaxial or stage light.








KemiaOptical coordinate measuring – vision measuring


The machine is computer-controlled and measure-ments are fully automated. The machine is capable tomeasure length, diameter, angle, straightness, flat-ness, parallelism, and roundness.

The machine is especially suitable for measurementsof circuit boards, thin-walled fragile plastic and metal-lic artefacts, and other artefacts that are inconvenientor impossible to measure with techniques using con-tact probes.

The artefact under study can be illuminated with ring,coaxial or stage light. There are four controllable seg-ments in the ring light and its height can be adjusted.

MIKES provides precise optical and contact dimen-sional measurements tailored according to custom-ers’ needs. Depending on the work order, a calibra-tion certificate or a field log is provided.

Table 1. Properties of the vision measuring machine.

Property Data

Measuring volume 350 mm x 350 mm x 150 mm

Size of the bench 490 mm x 550 mm

Max. workpiece mass 15 kgLowest measurementuncertainty (k=2),optical mode

U1XY = (0.8 + 2 L/1000) µm *U2XY = (1.4 + 3 L/1000) µm *U1Z = (3 + 2 L/1000) µm *

Lowest measurementuncertainty (k=2),contact mode

U1XY = (1.8 + 2 L/1000) µm *

Max. speed (rapid travel) 100 mm/s

Maximum acceleration 490 mm/s2

* L is length in mm. U1 uncertainty along one axel, U2 along two axels.

Figure 2. A contact probe complements the vision measuring machine






Chemistry

Calibration of line scalesand distance metersJarkko Unkuri, ResearcherTel. +358 40 410 [email protected]

Antti Lassila, Research ScientistTel. +358 40 767 [email protected]


Calibration services at inter-ferometric measuring railsLine scale interferometerMIKES calibration equipment for precision line scalesallows calibration of up to 1.12-m long line scales withbest possible accuracy. The measuring instrument islocated in an air-conditioned laboratory room in whichthe temperature is held at (20 ± 0.05) °C and the rel-ative humidity at (45 ± 5) %. The instrument performscomputer-controlled measurements of distances be-tween the graduation lines using a microscopeequipped with a CCD camera for line detection and aMichelson interferometer for position measurement ofthe microscope. The line scales are supported at Airypoints which minimizes bendings. The refractive in-dex of air is calculated from the measured air temper-ature, pressure and humidity data by using updatedEdlen’s equation. Thermal expansion is corrected to20 °C using material temperature measured with fourPt100 sensors attached to the line scale. The gradu-ation line distances can be between 10 µm ... 1.12 m.The line scale interferometer is suitable for calibra-tions of metallic or glass graduated line scales.

Calibration of line scalesand distance meters30-m measuring railMIKES 30-m measuring rail (Figure 2) offers goodpossibilities for calibration of precise length measur-ing devices. The temperature of the measurementroom is kept at (20 ± 0.5) °C and the relative humidity

at (45 ± 5) %. The 30-m rail is realised using a high-quality linear motion guide and a movable measure-ment carriage. A microscope, a CCD camera and amonitor used in line scale measurements aremounted on the carriage, The position of the micro-scope is measured using a laser interferometer.

The temperature stability of the measurement roomand precise gauges and sensors allow precise ther-mal expansion and refractive index of air compensa-tion.

Figure 1. Line scale interferometer.








KemiaCalibration of line scales and distance meters


The rail is suitable for calibration of various lengthstandards. The calibrated devices can be physical ar-tefacts like tapes and machinist scales or e.g. opticaldistance meters. Tapes and other flexible lengthstandards are tensioned using a standardized force,a force given by the manufacturer or a force sepa-rately agreed with customer. Most commonly a 50-Nm force of is used for tapes.

For thermal expansion compensation, a measuredtemperature and a coefficient given by the manufac-turer or by the customer are used.

Figure 2. 30-m measuring rail.

TraceabilityThe wavelengths of the lasers used in the line scaleinterferometer and in the 30-m measuring rail are cal-ibrated using national measurement standard oflength, iodine-stabilized He-Ne laser. The tempera-ture, pressure, and humidity sensors used in themeasuring rail are calibrated at MIKES.

Table 1. Line scales, measuring ranges and measurementuncertainties.

Device Measuringrange

Uncertainty(k=2)

Precision linescales, micro-scope scales

10 µm ... 1 m Q[6.2; 82L] nm**

Tapes, wires 0.001 m ... 30 m,(60, 90 ...) m Q[35; 2L] µm

Machinist scales 0.001 m ... 5 m Q[4; 1L] mm**

Circometer 0.1 m ... 9,55 m(diameter) Q[7; 2D] mm**

Plumb tapes 1 m ... 30,(60, 90) m Q[250; 5L] mm**

Other devices 0 m ... 30 m (case dependent)

L, D = measured length or corresponding diameter in me-ters

*The uncertainty of calibration is usually larger than theaforementioned uncertainties due to the uncertaintyresulting from the device to be calibrated.

**Calculation of uncertainty Q[x; y]=(x2+y2)1/2






Chemistry

Interferometric measure-ment of flatness and formBjörn Hemming, Senior ScientistTel. +358 50 773 [email protected]

Ville Byman, ResearcherTel. +358 50 386 [email protected]


FlatnessThe surface structure and especially the flatness ofthe surface are important features of various compo-nents used in different areas of technology and phys-ics. Examples of these include silicon wafers in sem-iconductor industry, sealing faces, bearing areas,contact surfaces in contact measurement methodsand surfaces of optical flats and lenses used for re-flecting and refracting light.

An optical flat is an easy to use transfer standard forflatness. In industry, optical flats are used, e.g. for

flatness measurements of gauge blocks and contactsurfaces of micrometre gauges. In these cases, thequality of the surfaces of optical flats is of essentialimportance for successful measurements of subjectsurfaces. Moreover, optical flats are used to transferflatness to interferometers measuring flatness and toother devices inspecting flatness in industry.

MIKES provides aforementioned measurements andmetrological traceability with its equipment for flat-ness and form measurements (Figure 1).

Figure 1. Calibration of an optical flat.








KemiaInterferometric measurement of flatness and form


Measurement methodThe measurement device for flatness at MIKES is aFizeau interferometer that uses a He-Ne laser atwavelength 633nm as a light source. Interferencefringes are obtained by adjusting a small angle be-tween the reference plane and the plane to be meas-ured. The shapes of the interference fringes are ana-lysed by using a so-called phase stepping method. Asa result, one receives deviations of the plane underinspection from the reference plane (Figure 2). Theadvantages of the method are speed, precision, andthe fact that the entire measurement area is meas-ured at once.

TraceabilityThe reference plane of the optical flat used in the in-terferometer is of high quality: deviations from a per-fect plane are less than 20 nm. The reference planeis calculated either by using an absolute three-pointmethod or by comparing it to a liquid plane. Opticalflats having different reflection coefficients are availa-ble which allows inspections of mirror surfaces as wellas glass surfaces.

Measurement servicesThe MIKES equipment (Zygo GPi) can be used forsurface profile measurements of objects that have di-ameters below 150 mm, best available measurementprecision being 45 nm. A prerequisite for such meas-urements is that the height variations of the artefactare less than 12 µm and slowly varying. As themethod is based on interference of light and thus it isa non-contacting method, it is also applicable for frag-ile materials. Moreover, it is applicable for very de-manding measurement tasks due to its precision.

Figure 2. An example of measured surface profile of an op-tical flat.

Figure 2. An example of measured surface profile of an optical flat.






Chemistry

Machine toolmeasurementsAsko Rantanen, Senior ResearchTechnician, Tel. +358 400 925 [email protected]



Demands of production and quality systems requireknowledge on the precision of machine tools. Differ-ent measurement are performed on machine toolsduring acceptance inspection, in connection withtransfers, and when striving for preventive mainte-nance. MIKES provides its wide experience on di-mensional and geometrical measurements, position-ing and repeatability accuracy measurements, andmeasurements on machine-tooled test work pieces.

The competent and experienced personnel of MIKES,modern equipment and continuous development ofnew measurement methods guarantee customers'precise measurements performed according to stand-ards.

Figure 1. Scale measurement for a machine tool.

Figure 2. Setup for machine tool measurements.








KemiaMachine tool measurements


Geometrical measurementsGeometrical measurements are used for finding outthe form defects in the most important organs of amachine tool and the mutual locations and positionsof the organs. MIKES performs geometrical measure-ments according to ISO and DIN standards. The mostimportant measurements subjects are measurementof spindle runout, the parallelism between the spindleand the machine, perpendicularity measurements,and straightness and perpendicularity measurementsof machine movements.

Accurate positioning andrepeatability measurementsSpindle positioning and repeatability measurementsreveal errors at different points of the spindle. Errorsin spindle movement can be compensated for by giv-ing the compensation values to the control unitmemory of the machine tool. The positioning meas-urement performed using MIKES laser interferometeris a fast and precise way to adjust the spindle move-ments of a machine (Figure 3); the measurement pre-cision is at its best below 0.001 mm/m.

Measurement of testworkpiecesMachine-tooling tests are used to find out the preci-sion of the machine in true machining circumstances.MIKES geometrical measurements and measure-ments on work pieces made in machine-tooling tests

complement each other. The work pieces are meas-ured in a temperature-controlled laboratory room us-ing versatile and modern measurement devices andmethods. MIKES have a variety of the most commonworkshop measurement equipment and a selection ofspecial tools (see Table 1).

TraceabilityAll measurement standards used in machine toolmeasurements are calibrated using similar but moreaccurate MIKES transfer standards.

Table 1. Devices used in machine tool measurements.

Geometrical,positioning andrepeatability meas-urements:

Measurements oftest workpieces

– laser interferometers– surface structure, form,

roundness and lengthmeasuring machines

– autocollimators – inductive sensors

– electronic spirit level – common workshopmeasurement devices

– inductive sensors – coordinate measuringmachine

– plumb

– other devices

Figure 3. X-axis errors of a broachingmachine before laser measurementand adjustment and after.






Chemistry

Measurement ofroundnessBjörn Hemming, Senior ScientistTel. +358 50 773 [email protected]



Roundness in mechanicalengineering industryApproximately 80 % of machined work pieces haveelements with surfaces of revolution. Roundness hasan important role for guaranteeing faultless operationof machines and devices. This is even emphasizedwhen reliability, longevity, low operating costs, andfriendliness to the environmental are required.

At MIKES, we perform measurements of roundnesson ring gauges, screw-plug gauges, slide bearings,metallic packings and hydraulic and pneumatic com-ponents. We also measure runout eccentricity, coax-iality, parallelism and straightness (Figure 1).

Figure 1. Roundness measurement is an essential part ofworkshop manufacturing.








KemiaMeasurement of roundness


Measurement potentialRoundness is measured either by using a rotatingspindle or by using a roundness measurement instru-ment equipped with a rotating table. Measurementscan be performed using several different filters ac-cording to the ISO 1101 standard’s definition (MZ) orother computing methods (MC, MI, and LS). The useof two alternative machines guarantees the customerthat the artefacts can be measured properly and costeffectively. More information on the machines can befound in table 1.

Cylindricity is measured using a machine equippedwith a rotating table (Figure 2); with almost the samesettings, the following measurement can be per-formed, also: coaxiality, runout eccentricity, parallel-ism and straightness. Cylindricity measurements area part of the calibration of ring gauges and screw-pluggauges.

TraceabilityTraceability to the sensors in both machines comesfrom magnification standards that are calibrated usingMIKES form measurement instrument which in turngets it traceability from gauge blocks calibrated usingan interferometer. The guide bars and shafts in themachines are calibrated using error separation.

Figure 2. Measurement instrument Talyrond 262 for round-ness and cylindricity.

Table 1. MIKES roundness and cylindricity measurement instruments.

Model Rotatingpart

Maximumheight of

the artefactmm

Maximuminner/outerdiameter ofthe artefact

mm

Maximummass of

the artefactkg

Other Expandeduncertainty

(k=2)

Talyrond 73HRroundness

spindle 400 175 / 300 100 surface can bediscontinuousor asymmet-rical

Q[0.01; 0.01R ] µm

Talyrond 262cylindricity

table 500 – / 350 50 surface can bediscontinuous

Q[0.1; 0.5L] µm

R is the deviation from roundness in micrometres; L is the height of the cylinder in metres; Q[x; y] = (x2+y2)1/2






Chemistry

Calibration of microscopesand calibration standardsVirpi Korpelainen, Senior ScientistTel. +358 50 410 [email protected]


Reliable measurement results in research, manufac-ture and quality control require knowledge of accu-racy of measurement instruments. Calibration is thebest way to check the accuracy and stability of theinstrument. The calibration can be done with cali-brated transfer standards. Official calibration certifi-cate guarantees traceability to the definition of themetre.

For optical microscopes MIKES provides calibrationof high quality line scales.

Scanning probe microscopes (SPMs) can be cali-brated using several kinds of transfer standards [1,2],which can be calibrated at MIKES. 1-D and 2-D grat-ings are calibrated either by laser diffraction or by me-trology atomic force microscope (MAFM). Pitch andorthogonality of the grid can be measured. Stepheight standards or z scale of 1-D or 2-D gratings canbe calibrated.[1] Guideline VDI/VDE 2656 Part 1 (Draft): Determination of geo-

metric quantities by Scanning Probe Microscopes - Calibrationof Measurement Systems.

[2] V. Korpelainen and A. Lassila, Calibration of a commercialAFM: traceability for a coordinate system, Meas. Sci. Technol.18 (2007) 395–403.

Figure 1. MIKES interferometrically traceable metrologyAFM (MIKES IT-MAFM).







KemiaCalibration of microscopes and calibration standards


Calibration itself gives information about the accu-racy of the instrument. Accuracy of the measurementcan be increased by corrections of the errors de-tected in the calibration either directly in the meas-urement software or after the measurement withseparate software.

The first step in the calibration is measurement of xand y scale errors by 1-D or 2-D gratings and z scaleerrors by step height standards. The calibration ofthe x and y scales gives also information about thelinearity of the scales. The linearity of the z scaleneeds to be checked by several different step heightstandards. Orthogonality errors can be detected

by 2-D grids. Out-of-plane errors can be measured us-ing a flatness standard. In the most accurate calibra-tions also some other error types has to be measuredand corrected; e.g. orthogonality of z-axis, rotationaland other guiding errors. There are also other errorsources, which should be taken into account, e.g. tip-sample interactions, vibrations, noise and thermal drift.Calibration period depends on the stability of the de-vice, e.g. microscopes with open loop scanner needcalibration before and after each measurement.

Figure 3. Some error types of SPMs.

Table 1. Calibration services for SPM standards.

Range Uncertainty

1-D grid (diffraction measurement)Pitch 300 nm – 10 µm 50 – 100 pm

2-D grid (diffraction measurement)Pitch 300 nm – 10 µm 50 – 100 pmOrthogonality

1-D grid (AFM measurement)Pitch, p 100 nm – 10 µm Q [3.4; 0.2 p/µm] nmOrthogonality 14 mradStep height, h 10 nm – 2 µm Q [2; 0.2 h/µm] nmFlatness 100 µm × 100 µm 5 nm

Step height standard 10 nm – 2 µm Q [2; 0.2 h/µm] nmFlatness standard 100 µm × 100 µm 5 nm






Chemistry

Length in geodesyMarkku Poutanen, Prof.Tel. +358 29 531 [email protected]

Paavo Rouhiainen,Senior Research ScientistTel. +358 29 531 [email protected]

Jorma JokelaResearch ManagerTel. +358 29 531 [email protected]

Finnish Geospatial Institute, FGIGeodeetinrinne 2, 02430 Masala,Tel. +358 29 530 1100,www.fgi.fi

Finnish Geospatial ResearchInstutute, FGIThe Finnish Geospatial Research Institute, FGI, ofthe National Land Survey of Finland maintains meas-urement standards for geodetic and photogrammetricmeasurements and is the National Standards Labor-atory of acceleration of free fall and length. The FGItakes care of the fundamental measurements in Finn-ish cartography and of geographical information me-trology and carries out scientific research in geodesy,geographic information sciences, positioning, naviga-tion, photogrammetry and remote sensing.

Calibration servicesThe FGI calibrates high precision electronic distancemeasurement (EDM) instruments, geodetic base-lines and photogrammetric test fields. Moreover, wecalibrate precise levelling rods, digital and traditional,and system calibration of digital level instruments.The calibrations are performed in addition to the Ma-sala laboratories at Nummela Standard Baseline andat Metsähovi Fundamental station. Most of our workis carried out in field conditions or conditions analo-gous to operating situations.

Figure 1 and 2. The Nummela standard baseline measuredby using the Väisälä comparator has been one of the mostaccurate and stable lengths over the past half decade.




http://www.fgi.fi/





KemiaLength in geodesy


Traceability and uncertaintyNational measurement standards for length at theFGI are a Väisälä interference comparator with aquartz meter system and a levelling rod comparatorsystem with a laser interferometer. All the measure-ments are traceable with a known uncertainty. Base-lines (864 m and 432 m) measured with the Väisäläinterference comparator have typically a measure-ment uncertainty ranging from 0.1 ppm to 0.2 ppm(k=2) and the measurement uncertainty for otherbaselines (1 m – 10 km) is at its best 0.2 ppm. Themeasurement uncertainty for calibration of levellingrods is 1 ppm and 5 ppm for calibration of levellingsystems.

Figure 3. Calibration of the most accurate distance metersof the world can be done at the Nummela Standard Base-line. Nummela scale has been transferred also to severalforeign baselines.

Research and developmentThe FGI carries out research and development onmethods and equipment for the measurements forgeodesy and geospatial information science. In addi-tion to length measurements, we perform other preci-sion measurement in surveying, e.g. measurementsof angle, azimuths, determination of coordinates andsatellite positioning. We also participate in GNSS me-trology related projects. International cooperation is acentral part of our work and we have measured base-lines in about 20 countries.

Figure 4. Calibration of a digital precise level instrument andsystem calibration of a barcode rod.

Figure 5. Research on the accuracyof GNSS antennas can be made atthe test field of the Metsähovi obser-vatory.






Chemistry

Water qualityTeemu Näykki, PhD, Associate ProfessorTel. +358 29 525 [email protected]

Timo Sara-Aho, ResearcherTel. +358 29 525 [email protected]

Finnish Environmental InstituteHakuninmaantie 6, FI-00430 Helsinki,Tel. +358 29 525 1000,www.syke.fi/envical/en

ENVICAL SYKE is focusing on the research and de-velopment of metrology in chemistry. Our activities in-clude development of accurate and traceable calibra-tion methods, testing the reliability of new measure-ment techniques and validation of methods of analy-sis and quality assurance.

Traceable calibrationsThe SYKE accredited calibration laboratory (K054:EN ISO/IEC 17025) produces calibration results withhigh accuracy and traceability and is responsible fordeveloping methods based on primary techniques.

In general, Isotope Dilution Mass Spectrometry(IDMS) can be regarded as one of the main reference

methods for elemental analysis, and appropriately ap-plied it offers the highest accuracy and smallestmeasurement uncertainty.

This method is used to measure the elemental con-tent (usually mass fraction) of an unknown test sam-ple, which has natural isotopic composition. Thissample is mixed with another sample (spike) contain-ing a known amount of the same element under in-vestigation. Isotopic composition of the spike sampleis known and it is different from the isotopic composi-tion of the test sample; usually such a way that therarer isotopes of the element are enriched. When thetest sample and the spike are completely mixed, theresulting mixture (blend) has a new (isotope diluted)

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KemiaWater quality


isotopic composition, where the isotope ratios are be-tween the test sample and the spike sample added.The isotope ratios of the mixture are measured andthe result is directly proportional to the mass fractionor concentration of the element in the sample.

At present, the scope of SYKE’s calibration laboratoryaccreditation includes measurement of lead (Pb) innatural water and mercury (Hg) in natural and wastewater. The methods are based on the isotope dilutioninductively coupled plasma mass spectrometric (ICP-MS) technique. The range of measurements is beingcomplemented with tests for dissolved oxygen andalso nickel and cadmium, listed as priority substancesin the Water Framework Directive. The isotope dilu-tion mass spectrometric technique is widely utilizedby SYKE also for measurement of organic chemicalcontaminants.

Our customer base consists of public and private par-ties requiring accurate and reliable measurement re-sults for their environmental samples. For instance,we have produced traceable reference values for pro-ficiency tests (PTs).

Research activitiesThe comparability of the measurement results is in-ternationally very important. Reliability and compara-bility of the measurement results can be improvedwith the realistic measurement uncertainty estima-tion, validation of the measurement methods, and en-suring the traceability of the measurement results.

ENVICAL SYKE is an experienced in research anddevelopment of the instrument’s reliability and proce-dures for measurement uncertainty estimation. Wehave constructed new tools for both laboratory meas-urements as well as for portable and continuous fieldwater quality measuring devices to indicate and im-prove the reliability of the measurement results. Ex-amples of these tools are MUkit- and AutoMUkit-measurement uncertainty calculation software.

We also actively participate in organizing proficiencytests for water quality sensor measurements.

In addition to maintenance of measurement stand-ards’ international traceability, our activities includenational and international communication, publica-tion, and training in the field of metrology. Upon re-quest, we arrange customized training in the estima-tion of measurement uncertainties in chemical meas-urements or validation of analytical methods.

Table 1. CNC data.

Quantity /method /

object

Measurementrange

CMC, Ex-pressed asexpandeduncertainty

(k=2)Chemical analysis, amount of substance

Mass fraction ofsoluble total mer-cury (Hg) in syn-thetic water, freshnatural water (notsea water) andwaste water

30 – 125 ng/kg>125 – 5000 ng/kg

6 %3 %

Mass fraction ofsoluble total lead(Pb) in syntheticwater and freshnatural water (notsea water)

0.200 – 1.00 μg/kg>1.00 – 100 μg/kg

0.030 μg/kg3 %

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Chemistry

VTT MIKES MetrologyTekniikantie 1FI-02150 Espoo

VTT MIKES-KajaaniTehdaskatu 15, Puristamo 9P19FI-87100 KAJAANI

Tel. +358 20 722 111Email: [email protected]


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MIKES METROLOGY Calibration Services · Calibration of direct voltage and current ... High voltage and high current..... 36 Acousic ct alibrations