High Precision Laser Interferometer Feedback Systems

8/9/2019 High Precision Laser Interferometer Feedback Systems

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High-precision laser interferometer

feedback systems


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In todays semiconductor and electronics marketplace, manymanufacturing equipment suppliers are having to adopt morefor less strategies to retain a competitive edge. This hasresulted from the continual drive to accommodate smallerfeature sizes, increase throughput and reliability whilstsimultaneously decreasing equipment footprints and costs.These requirements impact on every component integratedinto the final system.

For providers of position encoders this means ongoing OEMdemand for higher system resolution, velocity and accuracyspecifications, coupled with rapid installation times, low initialpurchase price and low cost of ownership.

Renishaw offers motion system equipment vendors a rangeof complementary solutions that can be effectively appliedto address these issues, over a broad range of applications,within many industrial sectors.

This document provides details on the range of laserinterferometer based encoders and related systems availablefrom Renishaw. It also provides an overview of linearand rotary encoder products, and the laser interferometercalibration system. A summary of each of these productranges follows.

Laser interferometer based feedbacksystems

- Provides interferometer performance (sub-nanometreresolution) with the ease of use normally associated withtraditional, scale based encoders.

Linear and rotary encoders

- A diverse selection of high speed linear encoders, highprecision angle encoders, magnetic rotary encoders andinterpolators.

Product scope

Laser interferometer calibrationsystem

- Providing 0.5 ppm linear measurement accuracy. Opticalaccessories available allow the determination of a machineslinear, angular, straightness, squareness and rotaryaccuracy.

Product

scope

High-precision laser interferometer feedback systems


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Experts in interferometryRenishaw began manufacturing the worldleading ML10 interferometer based calibrationsystem in the late-1980s, and has recentlyintroduced the next generation solution, theXL-80.

The success of the ML10, combined withRenishaws unsurpassed reputation in thefield of metrology, led the machine tool andaerospace industries to request a Renishawlaser system suitable for positional feedbackapplications. Consequently, during 1994,utilising the field proven technology of theML10, the HS10 laser scale was released.

This robust unit consistently confirmed itsreliability, operating in inhospitable machineenvironments worldwide on axis lengths to60 m.

In 2001, the RLE10 opened up the world ofinterferometry to applications which werepreviously unable to use laser interferometerbased encoders: traditional integrationbarriers associated with conventionalinterferometer systems were entirelyeliminated with the release of Renishaws newfibre optic based system.

The RLE range now includes a rangeof complementary components allowingconfiguration of the ideal solution on anapplication-by-application basis.

Why interferometry?

Laser interferometers provide the highestpositioning accuracy for your motion system:

Interferometers have an intrinsically highresolution- The measurement reference ofthe RLE interferometer is the internationallyrecognised wavelength of Helium Neon(HeNe) laser light. At 633 nm, this is muchfiner than the pitch of typical scale gratingsused in many optical encoder systems.This enables the RLE to easily achieve highresolutions, free from the sub-divisional(interpolation) errors experienced whenusing conventional encoders.

System development

ML10 calibration laser

HS10 laser scale

Dual axis RLE system

XL-80 calibration system

Interferometers have the ability toeliminate Abb errors- Mechanicalconstraints often necessitate thatconventional encoders are mounted aroundthe periphery of the working zone. Theresulting offset, between the measurementaxis and the work surface, leaves systemaccuracy extremely sensitive to any pitchor yaw errors within the motion system. Incontrast, the absence of the mechanicalscale and the ability to measure off aplane mirror target optic, allows the laserinterferometer to take measurementsdirectly in line with the work-piece, therebyavoiding Abb offset and the sensitivity toaxis pitch and yaw.

Abb error can be calculated as d Sine

Overcoming traditionalbarriers

Conventional laser interferometer schemes

use separate laser heads, interferometers,

reflectors and detector units. The laser beamis routed between these isolated components

by a complicated network of beam splitters

and benders, resulting in a bulky, complex,

system which is time consuming and difficult

to set-up, align and maintain.

The RLE uses optical fibres to deliver the

laser beam directly to remote launch units

which also contain the interferometer optics

and detector. This method gives the RLE a

number of crucial advantages that minimise

integration time and hence cost.

System footprint is dramatically reduced -

only the reflector and miniature launch unit

are mounted on the motion system. The laser head can be mounted remotely

from the measurement axis, eliminating a

potential heat source.

Complicated beam routing optics become

redundant, reducing alignment to just two

components.

A beam steerer, incorporated into each

launch unit, provides beam adjustment for

rapid alignment to the axis of motion.

d

Abb error

3

System

development


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The RLE system is a unique, advancedhomodyne laser interferometer systemspecifically designed for position feedbackapplications.

Each RLE system consists of an RLU laserunit and one or two RLD10 detector heads,the model of which is dependent upon therequirements of the specific application.

The system provides the user with sub-nanometre resolution capability at velocities ofup to 2 m/sec (80 inch/sec) for axis lengths ofup to 4 m (160 inches).

To maximise application flexibility, all RLEsystem components are compatible, enabling

the best solution for individual applications tobe selected at component level. The rangeof user selectable components within theRLE system includes two laser units and sixRLD10 detector heads.

RLU10 laser unit


Introduction to the RLE

RLE10 laser system

RLU laser unitsThe laser unit is the heart of the RLE system,containing the HeNe laser tube, the fibreoptic launch and the majority of the systemelectronics.

Due to its fibre optic launch method, the RLUlaser unit can be mounted remotely from theprecision motion stage thereby eliminating apotential heat source without any increaseddemands on alignment stability. This ensuresreliable operation.

The position output from the RLU is directlyavailable in differential digital RS422 formatand/or 1 Vpp analogue sine/cosine formats.From the digital output, resolutions to10 nm are available. The signal period forthe analogue output is 158 nm when usinga double pass plane mirror or differentialinterferometer, and 316 nm for a single passretroreflector based system. Optionally,the RPI20 parallel interface can be usedin combination with the analogue output toprovide resolutions to 38.6 picometres.

Two RLU models, referred to as RLU10and RLU20, are available with frequencyspecifications of 50 ppb and 2 ppb overone hour respectively. Accordingly, thesystem is referred to as either RLE10 orRLE20. (RLE10 systems incorporate anRLU10, RLE20 systems an RLU20.)

X-Y stage application- Anorad - RockwellAutomation

Introduction

totheRLE


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RLE system benefitsThe unique fibre optic launch basedarchitecture allows the RLE to provideinterferometer system performance with theease of use normally associated with glass ortape scale based encoder systems.

Architectural advantages are achievedthrough a combination of the followingfeatures:

Fibre optic laser launch- Enables thelaser light to be taken directly to wherethe axis position needs to be measured,eliminating the requirement for remotebeam benders, splitters and associatedmounts. Installation time and alignmentcomplexity are significantly reduced whilstthe reduction in space required aroundthe motion system for laser beam pathscan provide an opportunity for substantialfootprint reduction.

Integrated laser beam steerers-Incorporated in all RLD10 detector heads tofurther reduce alignment complexity.

Integrated interferometer optics- MostRLD detector heads include pre-alignedinterferometer optics and fringe detectionsystem, making installation a case of simplyaligning the RLD10 head with the target

optic fitted to the moving element. This isan operation not dissimilar to aligning areadhead and scale on a linear encodersystem.

Removal of potential thermal errorsource- The fibre optic launch enables theRLU laser head to be mounted in a locationthat is insensitive to the heat dissipated,without affecting laser alignment complexityor alignment stability requirements.

RLD10 single passinterferometer

RLD10 double passinterferometer

RLD10 differentialinterferometer

Introduction to the RLE

Beam steering capabilities of the RLD10differential interferometer detector head

Reference beampitch (left) and yaw(right) adjusters

Measurement beampitch (left) and yaw(right) adjusters

RLD detector unitsMost RLD10 detector units contain the fr ingedetection scheme, interferometer optic andintegrated laser beam steerer(s). Six differentRLD detector heads are available based onfour variants.

Single pass interferometer - Uses anexternal retroreflector target optic forlinear applications with axis lengths to4 m. Available with 0 or 90 beam launchorientation. Directly produces a sinusoidaloutput with a signal period of 316 nm thatenables digital quadrature resolutionsto 20 nm to be provided. Optionally, the

RPI20 parallel interface can be used toextend resolution (LSB) to 77.2 picometres.

Double pass interferometer- Requires anexternal plane mirror target optic forX-Y applications with axis lengths to 1 m.Available with 0 or 90 beam launchorientation. Directly produces a sinusoidaloutput with a signal period of 158 nm thatenables digital quadrature resolutions to10 nm to be provided. Optionally, theRPI20 parallel interface may be used toextend resolution (LSB) to 38.6 picometres.Low power dissipation models (0.14 W) arealso available.

No internal interferometer - The absenceof interferometer optics within this headenables the RLE system to be utilised withexternal optics to perform linear, angle andstraightness measurements. Only availablewith 0 beam launch orientation.

Double pass differential interferometer(column reference)- Requires externalplane mirror targets for both reference andmeasurement interferometer arms for X-Yapplications with axis lengths to 1 m. Thereference arm should be a fixed distance ofup to 0.5 m. Produces a sinusoidal outputwith a signal period of 158 nm, enablingdigital quadrature resolutions to 10 nm.

Use of the RPI20 parallel interface willextend resolution (LSB) to 38.6 picometres.

As the measurement and reference beampaths have an element of commonality, thisdetector head offers a number of benefits.

Measures stage versus column or

workpiece versus tool for a true differentialmeasurement.

Removal of errors due to thermal translation

of the interferometer mounting position. Minimisation of the effects of laser

frequency instability as the differentialpath length (between measurement andreference paths) is reduced.

Common mode environmental effectsenable the detector head to be mountedoutside the process chamber with minimalaffect on positioning accuracy.

5

Introduction

totheRLE


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Unique fringe detectionsystem

Every RLE interferometer system comprisesa combination of RLU laser unit and RLDdetector head(s). The RLD detector headcontains the interferometer (single pass,double pass or differential), laser beamsteerer and fringe detection scheme. Figure1 shows a schematic of a double passinterferometer RLD detector head.

The unique fringe detection scheme includesa multi-channel integrated photodetector.This advanced approach to homodyne fringedetection is fundamental to the superior

performance provided by RLE systems.

The multi-channel photodetector (see figure 2)enables simultaneous real-time productionof sine, /sine, cosine and /cosine. Inaddition, this approach minimises alignmentsensitivity (see figure 2, page 7) and reducesinterferometer system footprint.

Within the detection system, the individual,orthogonally polarised, reference andmeasurement beams are recombined andoverlaid by an optical wedge. Here thecoherency of the two beams causes thewavefronts to interfere (as shown in figure 5).Bright interference fringes appear where

intersecting wavefronts are in phase with eachother. Dark fringes are generated when thewave fronts are in anti phase. Adjacent brightand dark fringes are separated in phase by180.

The sinusoidal interference pattern producesfour simultaneous real-time outputs of sine,

/sine, cosine and /cosine from the integratedphotodetector, shown as A, B, C and D (infigures 4 and 5), representing a sampling ofthe interference pattern at four points acrossthe 360 fringe separations.

Following fringe detection, the signals areprocessed by a combination of pre-amplifiersand differential amplifiers. The differentialstages amplify the difference voltage betweenthe two inputs of sine, /sine, cosine and

/cosine. This removes any DC offsets,

generating sine and cosine signals equal tothe phase difference alone and independentof any common signal noise.

Figure 1: RLD detector head

Figure 2: multi-channelphotodetector

Figure 3: photodetectorPCB from detector head


21stcentury homodyne interferometry

Figure 4: optical wedge and interference patterns Figure 5: constructive and destructive interference

21st centuryhomodyne

interfero

metry

Photodetector

633 nm

Wave fronts out of phase:

destructive interference

Photodetector

Relative movement of the

wave fronts in and out causesa movement of the fringe

pattern on the photodetectorfrom left to right.

The angle between the beams

determines the fringe pitchincident on the photodetector.

Fringe

pattern

Wavefronts

in phase:constructive

interference

Dashed and continuous lines

are separated in phase by 180

Optical wedge

Fringe patternPhotodetector

Measurement beam(vertically polarised)

Reference beam

(horizontally polarised)

Photodetector

top surface

Fringe pattern

B C DA B C DA B C DA


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Mirrors mountsTo enable mirrors to be mounted and alignedon the motion system, Renishaw can alsoprovide adjustable mounts for use with mirrorsup to 350 mm in length with 25 mm x 25 mmcross section.

These mounts enable adjustment of bothmirror pitch and yaw, with screw adjusterspositioned to allow easy access from the frontand sides of the mirror respectively.

The mirror mounts provide up to 2.5 ofyaw adjustment (actual adjustment range isdependent on the length of the mirror) and1 of pitch adjustment.

Mirror mounting block

Mounted mirror

RLE system accessories

X-Y stage application- Aerotech Inc

AccessoriesTo complete an RLE interferometer systemrequires only one additional, external targetoptical component fitted to the motion system.(When using the differential interferometer,optics are required on the motion system anda fixed reference point e.g. column/tool.)

In applications where a single passinterferometer is used, a housed retroreflectoris supplied with the RLE system kit.

For applications that use standarddouble pass or differential interferometerconfigurations, Renishaw can supply planemirrors and adjustable mirror mounts, ifrequired.

Plane mirrors

Plane mirrors are manufactured on aZerodur(or similar) substrate and have ahard oxide dielectric coating. A summarymirror specification is shown below. Pleasecontact Renishaw for a detailed specificationof specific mirror lengths.

Local flatness 97%

Operating 0 C to 40 C temperature Cross section 25 mm x 25 mm

RLEsystem

accessories



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The RPI20 parallel interface acceptsdifferential analogue 1 Vpp sine/cosine signalsand provides an output in parallel format withup to 36-bits of position data being available.

Features of the RPI20 include:

4096x interpolation Analogue input bandwidth of


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The REE range of interpolators producehigh-resolution digital quadrature signalsfrom analogue 1 Vpp sine and cosinesignals supplied by the position encoder. Theresolution of the digital output quadrature isa function of the distance represented by one360 cycle of the input analogue signals, andthe interpolation factor.

When REE interpolators are used withthe RLE laser interferometer, the followingresolutions can be obtained:

Interferometer type Double pass(plane mirrortarget optic)

Sinusoidal input resolution 158 nmAvailable output resolutions 0.39, 0.79,

1.58 nm*

Interferometer type Single pass(retroreflectortarget optic)

Sinusoidal input resolution 316 nmAvailable output resolution 0.79, 1.58,

3.16 nm*

Interpolation technique

REE 200 interpolator

Performance summary table

REE series interpolators

= arcTan x

y

Sine (x)

Cosine (y)

* Note that maximum system velocity reduces as output resolution becomes finer. For part numbering and velocity limitationinformation, please refer to the table above.

** For information on the compatibility of other interpolators with the RLE system, please contact your local Renishawrepresentative.

Each interpolator module includes referencemark circuitry, analogue input amplitudedetection and interpolation integrity monitor.

Analogue input amplitude is communicatedto the user through an integral multi-colourLED, error output signal, and tri-stating of theoutput quadrature when inoperable amplitudelevels are reached.

Additionally, the error line is asserted if themotion system velocity exceeds the specifiedmaximum indicating an overspeed condition.

REE interpolators are available withinterpolation factors of 100, 200 AND 400**with each interpolator recommended for use

with laser interferometers having output anupdate rate of 20 MHz.

An REE used with a plane mirrorinterferometer that has an analogue signalperiod of 158 nm would directly produce edgeto edge separations of 39.5 nm. With x400interpolation, this resolution is increased to0.395 nm.

Interpolator type Part number Plane mirror system Retroreflector system

Resolution (nm) Maximum velocity(mm/s)

Resolution (nm) Maximum velocity(mm/s)

REE 100 REE0100A20B 1.582 17.7 3.164 35.4

REE 200 REE0200A20B 0.791 8.8 1.582 17.7

REE 400 REE0400A20B 0.395 4.4 0.791 8.8

Linear air bearing stage- Danaher Motion

0

REEseries

interpola

tors



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11

RCU10c

ompensation

systemThe Renishaw RCU10 quadraturecompensation system provides significant

improvements in process accuracy andrepeatability by addressing environmentalerror sources associated with the feedbacksystem, the workpiece and the machinestructure; all in real time.

To achieve this, the RCU10 compensator islocated directly within the position feedbackloop. Taking readings from the encoder andenvironmental sensors, the position feedbackis then modified to remove associated errorsbefore the signals are supplied to the motioncontrol.

The system can be used with any linearencoder that produces differential digitalquadrature and can implement userselectable combinations of the followingalgorithms:

Refractive index compensation (for laserinterferometer based encoder systems)

Scale compensation (for tape or glassbased encoder systems)

Workpiece compensation Machine structure compensation

The RCU10 system accepts a wide range ofdiscrete digital quadrature resolutions and theuser can select to receive the compensatedoutput in either differential digital or differentialanalogue 1 Vpp sine/cosine formats.

To perform compensation, the RCU10 unitconverts the quadrature input supplied by theencoder into unit of resolution count pulsesand an associated direction (up/down line).This is followed by a digital scaling circuitwhich allows the effective resolution to bechanged, enabling the conversion of laserwavelength related units into more standardengineering units. (For example, in machinetool applications 633 nm is often converted

to 1 m.) After the scaling circuit, an injectorarrangement allows unit of resolution pulsesto be added or subtracted into the countpulse stream. It is through a combinationof scaling and injection of unit of resolutionpulses that the compensation is implemented.After these corrections have been applied tothe feedback, it is then converted to digitalquadrature or analogue sine/cosine anddispatched to the control system. This wholeprocess incurs a delay of less than 2 s.

RCU10 compensationsystem

Internal view of RCU10

RCU10 compensation system

Distance scalingfunction

Pulse injectionor subtraction

Quadrature regeneratorand counter

Refractive index

compensationThermal expansion

compensation

Digital signal processor

Environmental

sensor network

Motion control system

Quadrature from encoder

Quadrature decoderand counter

RCU10 compensation unit


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When using any laser interferometer systemin non-vacuum conditions and where itis not possible to reference the encodersystem output against a known distance(for example the distance between fuducialmarks on a wafer), some form of refractiveindex compensation is required to maintainaccuracy under changing environmentalconditions.

This is because the fundamental fringespacing (unit of count) is a function of thewavelength of the laser light which varies veryslightly depending on the refractive index ofthe air through which it travels. This dependsprimarily on its temperature, pressure and

humidity.

The following changes in environmentalconditions will result in a 1 ppm variance inlaser wavelength*:

~1 C variance in air temperature ~3.3 millibar variance in air pressure ~50% variance in % RH

* These sensitivities are based on changesfrom a nominal atmospheric environment of20 C, 1013.25 millibars, 50% RH

Correction for refractive index variation iscalculated within the RCU10 using Edlensequation, with the environment being sampled

at intervals of fractions of a second via theunits pressure and humidity sensors.

The RCU10 system offers the followingfeatures/benefits:

1 ppm positioning (with refractive indexcompensation only) over a broad range ofenvironmental conditions.

Simultaneous implementation of multipleerror correction algorithms.

Use of individual air temperature sensorsfor each axis allows the environment inclose proximity to the laser beams tobe sensed, rather than inferring that theenvironment is consistent throughout themachine.

Application flexibility through theRCU10-CS configuration software enablesthe RCU10 system to be configured tomatch the requirements of the application.Following configuration, the PC isdisconnected and the RCU10 operates asa standalone system.

One to six axis capability. Although eachRCU10 unit is a single axis compensator,multi-axis systems can formed using anumber of individual RCU10 compensatorsconnected via a high-speed serialcommunications link to facilitate datasharing.

Extended diagnostic and error reportingsystem enables integrity of thecompensated signal to be assured.

RCU10 compensation system

2

RCU10c

ompensation

system

System configurationscreen

Sensor configurationscreen

Multi axis RCU10 systemconfiguration

Input format

A

B

Aquad

B quad

Output formats

RCU10Motion controller

RG linear encoder

RLU10/RLU20

The RCU10 can be used to compensate digital position feedback signals from a variety ofsources and can produce compensated output in analogue or digital format.


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13

Typicals

ystem

configur

ations

Retroreflector (single pass) RLE interferometer system forlinear applications with axis lengths of up to 4 m. Optionally,the RCU10 compensation system can be used to correct forrefractive index variation.

RLU10 and RLU20 laser units are fully compatible with thecomplete range of detector heads: RLD10 0 output and 90output (available configured for either retroreflector (singlepass) or plane mirror (double pass) applications), and theRLD10 DI differential interferometer.

RLU10 and RLU20 laser units are available in single or dualaxis variants supplied with one or two RLDs as appropriate.

RLE interferometer system with REE interpolator used toconvert analogue sinusoidal output (from RLE) to high-resolution differential digital quadrature signals. Suitable forretroreflector (single pass), plane mirror (double pass) anddifferential configurations.

RLU10/RLU20

RLD 0

RLD 90

RLD DI

motion controller

RLU10/RLU20(single axis)

RLD

REE interpolator

Typical system configurations

Plane mirror (double pass) RLE interferometer system forX-Y applications with axis lengths of up to 1 m. Optionally,the RCU10 compensation system can be used to correct forrefractive index variation.

motion controller

2 off RLDs

RLU10/RLU20(dual axis )

2 off RCU10


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Typical system configurations

4

Typicals

ystem

configur

ations

RLE interferometer system with dual axis VME configuration(2 off RPI20 36-bit parallel interface modules) for ultra-highresolution applications.

RLE interferometer system with RPI20 36-bit parallel interfacefor ultra high-resolution applications.

RLE interferometer system with differential interferometer(RLD10 DI) detector heads.

motion controller

RLD

RPI20RLU10/RLU20(single axis)

motion controller

2 off RLDs

RLU10/RLU20(dual axis)

2 off RPI20(VME)

motioncontroller

RLU10/RLU20(dual axis)

processchamber

column


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15

Typicals

ystem

performance

The graph below has been compiled from results ofindependent system testing performed by Physikalisch-Technische Bundesanstalt (PTB), Germany.

The graph shows the measurement difference between thePTB reference laser system and a Renishaw RLE10 laserinterferometer system measured over a range of 0 m to 2 m.Compensation for refractive index variation was applied tothe outputs of both lasers. Corrections to the PTB laser werecalculated using sensors and an algorithm supplied by PTB.The Renishaw laser output was compensated by a RenishawRCU10 quadrature compensation system.

Typical system performance

The Renishaw RLE10 system tested comprised an RLU10,with a single pass (retroreflector) interferometer RLD10detector head. The RCU10 was configured to performrefractive index compensation only: no material compensationwas applied to either the PTB or Renishaw laser.

The specification for an RLE10 interferometer systemcompensated for refractive index effects by an RCU10 is1 ppm, as indicated by the upper and lower limit lines on thegraph. Actual results achieved in this test show the accuracyof the tested system to be approximately 0.24 ppm, equivalentto 0.24 m/m.

System accuracy is quoted to the internationally recognised95% confidence level (k=2).

PTB is the German national metrology laboratory based in

Braunschweig, and is a signatory to the Mutual RecognitionAgreement for national measurement standards and forcalibration and measurement certificates issued by NationalMetrology Institutes, signed in October 1999. This agreementmeans that results obtained by PTB are recognised by asignificant number of national laboratories including thosein The Peoples Republic of China, Israel, Japan, TheNetherlands, Sweden, United Kingdom and United States ofAmerica.


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6

Warranty,service

andsupport

WarrantyAll Renishaw laser encoder products arecovered by a 24-month warranty as standard.

Service and support policy

Renishaw has served the metrologyrequirements of the manufacturing sector forover thirty years, allowing the development ofunparalleled, first hand knowledge of servicerequirements and expectations.

Building on this knowledge, Renishaw hasestablished a first class, global service andsupport network, backed by specialisedapplication engineers who can providedetailed recommendations regardingindividual proposed applications.

The support function provided by theseengineers is further enhanced by our servicestaff. Service technicians are ready toprovide prompt and efficient service andrepair assistance.

A range of service levels are available to suitindividual customer needs.

Service options Advance RBE(repair by exchange)

Through this service we ship you as newreplacement product. This simple to useoption is designed to minimise downtimecaused by in-service failures. To takeadvantage of this option, simply call yourlocal Renishaw office, tell us the serialnumber of your system, and well ship youa replacement.

Post inspection RBE This quick response option provides you

with factory standard, replacement product,after we have inspected your returned

system. Send us your faulty system, ourtechnicians will inspect it, diagnose anyfaults and either fix it or provide you witha replacement system, built to as newstandard.

These RBE service options enable existingcustomers to replace faulty product, withminimal expenditure and downtime, withoutcompromising process integrity.

To take advantage of the RBE policy andpricing structure, original product must bereturned to your local Renishaw office.

Repair Skilled technicians at our UK service centre

will test your returned system and repairidentified faults.

Repair charges will always be advised, andauthorisation received, prior to any repairwork being undertaken.

Warranty, service and support

Specialised applicationsengineers are availablefor immediate telephonesupport

Frequency stability testfacility; Renishaw plc

Global sales andsupport network


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17

Complem

entary

solutionsand

Complementary solutions and product offerings


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Complementary solutions: optical encoder products

RGH22

RGH24

RGH22 Compact and robust housing Integral interpolation and set-up LED Resolutions available: 5 m, 1 m, 0.5 m,

0.1 m and 50 nm Reference mark and single or dual limit

switch sensors 16.0 mm x 44.0 mm x 27.0 mm

(H x L x W) Mitsubishi Melservo serial comms

compatible version also available

RGH24

Super-compact and robust housing

Integral interpolation and set-up LED Resolutions available: 5 m, 1 m, 0.5 m,

0.2 m, 0.1 m, 50 nm, 20 nm and 10 nm Reference mark or single limit switch

sensor 14.8 mm x 36.0 mm x 13.5 mm

(H x L x W)

RGH25F

Ultra-high resolution Ultra-compact and robust housing Resolutions available: 5 m, 1 m, 0.5 m,

0.2 m, 0.1 m, 50 nm, 20 nm, 10 nm and5 nm

Self-tuning adaptive electronics give low

SDE Ultra-high vacuum version available 10.5 mm x 36.0 mm x 13.5 mm

(H x L x W) Reference mark or single limit switch External interpolation with set-up LED

Optical linear encodersRenishaw also offer a wide range of compactoptical and magnetic encoder systems tosuit the requirements of the diverse industrysectors served.

Renishaws innovative non-contact opticalscheme provides excellent metrology and highresolution with zero mechanical hysteresis,yet can withstand a variety of contaminantssuch as dust, light oils and scratches withoutcompromising signal integrity.

The flexible gold plated scale can be cut tosuit any axis length and the special formulaself-adhesive backing removes the need fordrilling and tapping: saving time and money.

RG2 20 m

The RG2 is an open, non-contact opticalsystem, eliminating friction and wear, whilstpermitting reliable high-speed, high-resolutionoperation. Unique filtering optics ensureexcellent signal stability even in workshopenvironments.

All readhead types come with industrystandard analogue or square wave outputs,with 20 m analogue signal period and digitalresolutions from 5 m to 5 nm. All systemsincorporate a unique, integral set-up LED,

which lights green when optimum installationhas been achieved.

Automated circuit boardtester - Probetest

8

solutions:optical

encoder

products

RGH25F


19/24

Complementary solutions: optical angle encoders

Available in a wide range ofdiameters

software

Features of the range include: Non-contact open optical system IN-TRACbi-directional reference mark

and dual limit outputs Graduation accuracy to 0.5 arc second System resolution to 0.0038 arc second Patented taper mount simplifies integration

and minimises installation errors Large internal diameter for ease of

integration 30 mm to 550 mm with line counts from

4,720 to 86,400 Operating temperatures up to 85 C Speeds over 4,500 rev/min Dynamic signal control ensures a cyclic

error typically better than 30 nm Integral LEDs for optimum set-up and

system diagnostics Comprehensive software

for ease of installation and real-timediagnostics via USB

Filtering optics providing excellent dirtimmunity

19

Complem

entary

solutions:optical

RESM angle encoderRenishaws encoder range offershigh-speed, reliable, non-contact performancecombined with advanced features includingthe IN-TRAC auto-phase optical referencemark. The RESM angle encoder comprisesthe RESM ring, the SR readhead and Siinterface.

The RESM is a one-piece stainless steelring with 20 m scale marked directly on theperiphery. It features the IN-TRAC opticalreference mark, which repeats, regardless ofdirection, at operational speeds over4,500 rev/min (52 mm) and up to 85 C. The

SR readhead is sealed to IP64, enabling aquick recovery from coolant splashes andimmersions.

In addition, the RESM angle encoder usesintelligent signal processing to

ensure excellent reliability and low cyclicerror, whilst comprehensive software enablesoptimum set-up and real-time systemdiagnostics via a PCs USB port.

For applications that require the highestangular accuracy the REXM angle encoderoffers new levels of performance - better than1 arc second total installed accuracy, zerocoupling losses and exceptional repeatability.

REXM features a thicker cross-sectionto minimise all installation errors excepteccentricity, which is easily correctedusing Renishaws new DSi (Dualinterface).


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Linear vacuum - REF Resolutions available: 0.2 m, 0.1 m,

50 nm, 20 nm, 10 nm and 5 nm System comprises: RGH25F UHV readhead REF interface RGS20-S scale

Rotary vacuum - REF

Resolutions available: 0.2 m, 0.1 m,

50 nm, 20 nm, 10 nm and 5 nm System comprises: RGH20F UHV readhead REF interface

RESR ring

Complementary solutions: UHV encoder products

RGH25F UHV

Thermo VG Scientific

For further information on the available range of Renishaw optical encoder products, please contact your local Renishaw office.


Ultra-high vacuumcompatible readheadsystems

Renishaws vacuum range has beenspecially constructed from clean UHVcompatible materials and adhesives to givelow outgassing rates and a clean RGA. Thereadheads also consume less current tominimise heat dissipation. The RGH20FUHV is designed for use with Renishaws20 m RESR angle encoder to provideprecision feedback for rotary motion in UHVenvironments.

The RGH20F UHV and RGH25F UHVreadheads are used with the REF interfacewhich incorporates automatic gain controland unique self-tuning adaptive electronics.Combined with filtering optics, these ensureexcellent signal strength integrity and lowcyclic error.

Key features of the range include: Clean RGA Bake out temperature of 120 C Low outgassing rates Low power consumption readheads (50 mA) Resolution to 5 nm Low cyclic error (


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XL-80 calibration laser

The optics family

Ease of set-up and adjustment- Tripodmounting removes the laser from the machineunder test, helping to reduce thermal effectsand the risk of damage during operation,whilst the tripod stage provides angularrotation and translation of laser position.Laser pre-heat is less than six minutes, andthe USB connectivity of both XL-80 andXC-80 eliminates the requirement foradditional interface units.

Environmental compensation- The greatestuncertainty in most laser measurementsarises from variations in environmentalconditions (air temperature, air pressure andrelative humidity) from NTP values. Typical

variations in these conditions can introduce20 ppm uncertainty to a measurement.Without accurate sensors and compensationyou cannot achieve accuracy except undercontrolled laboratory conditions e.g. in avacuum. To compensate for environmentalfluctuations during measurements, Renishawuse highly accurate environmental sensorsand the XC-80 environmental compensationunit.

Performance specifications- Renishawsaccuracy specification is derived inaccordance with recognised procedures forthe calculation of measurement uncertaintyfor laser stability, sensor output and all key

parameters and calculations affecting thefinal measurement. Overall system accuracyis quoted to the internationally recognised95% confidence level (k=2), and includesallowance for drift in service.

Constant visibility- Status LEDs provideconstant indication of current system status.

Complementary product offerings: calibration hardware

XL-80 laser measurementsystem

The Renishaw XL-80 laser measurementsystem is designed to take motion systemcalibration to the next level. A compact,lightweight laser head (XL-80) andindependent environmental compensator(XC-80) provide linear measurement accuracyof 0.5 ppm over the complete environmentaloperating range: 0 C to 40 C and 620 mbarto 1150 mbar.

With linear, angular, rotary, flatness,straightness and squareness measurementcapability, the single frequency XL-80 laser

unit provides nanometre resolutions atfeedrates of up to 4 m/s and by selecting theswitchable long-range option, axis lengths to80 m can be calibrated using a single laser.

When you purchase a laser system fromRenishaw, you are not only buying the mostaccurate and flexible system available,you are also buying into a worldwidesupport network that understands machinemetrology, machine service and the demandsof maintaining accuracy in a productionenvironment.

Interferometry is traceable- All XL-80measurements are interferometric and

therefore utilise the traceable internationalstandard of laser light. Other systems whichuse electronic targets to measure pitch, yawand straightness errors often compromisemeasurement accuracy and stability.

Separate interferometer- The XL-80 systemutilises a remote interferometer rather thanone mounted on or inside the laser head, thusavoiding thermal drift.

Laser frequency stability- 0.02 ppm overany one hour and 0.05 ppm over one year.

Intelligent- System auto-senses/auto-adjuststo the input voltage.

21

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entary

product

offerings:


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To coincide with the release of the XL-80laser calibration system, Renishaw have alsolaunched revised and updated versions of itstwo calibration software packages, LaserXLand QuickViewXL.

These multi-lingual packages are compatiblewith WindowsXP and Windows Vista only.

LaserXL

LaserXL measurement software allowsusers to perform static and dynamicmeasurements to determine a machineslinear, angular, flatness, straightness andsquareness measurements, with the dynamic

measurement mode offering 12 userselectable data capture rates between 10 kHzand 50 kHz

Standard report options conform to a numberof international machine performancechecking standards, including ISO, ASME,JIS and GB, plus comprehensive Renishawdeveloped analyses.

QuickViewXL

QuickViewXL is designed specifically toprovide real-time information on the dynamicbehaviour of your motion system. Whetheryour application is in machine tool, sensors,printing and imaging equipment, electronicor biotechnology process equipment,QuickView is an ideal metrology tool.

Knowledge of a position sensitive machinesdynamic characteristics - acceleration,velocity, vibration, settle time, resonance anddamping - is critical in many applications, asthese characteristics will influence operationalcapabilities such as positional accuracy,repeatability, surface finish, throughput andwear.

For years, electronics engineers haveused oscilloscopes to study high-speedvariations in voltage or current. Renishawsnew QuickViewXL software offers similar

capability to mechanical engineers, allowingthem to study live traces of linear or angularposition versus time.

With QuickViewXL, your XL-80 systembecomes a tool not just for equipmentcalibration, but also an investigative andanalytical tool for use during developmentand build processes. Quality assuranceprogrammes, continued development ofhigher speed machining processes and thedemand for increased reliability, have allhighlighted the requirement for such a tool.

Complementary product offerings: calibration software

For further information on the available range of Renishaw calibration products, please contact your local Renishaw office.


Optional small linear opticskit reduces mass effects ondynamic performance

Typical application fordynamic data capture:gantry flat panel inspectionstage (photo courtesy ofDanaher Precision Inc)

An intuitive and easy-to-use softwarepackage, QuickViewXL provides a real-time, graphical view of the XL-80 lasersmeasurement data sampled at 50 kHz, with1 nm linear and 0.01 arc second angularresolution.

Using an icon based interface, with a singlescreen for set-up and data viewing, theoscilloscope function provides a graphicdisplay of the captured data. Followingon-screen review, data can be exported forfurther analysis into various applicationssuch as MathCAD, Mathmatica and Excel, inaddition to FFT analysis within RenishawsLaserXL software.

Capabilities include: Live data display of position, velocity or

acceleration traces Choice of triggering modes (rising edge,

falling edge, single shot, multi-shot)

Typical benefits: Streamline your R&D process, bringing

new product to market more swiftly Diagnose production problems Enhance field service capabilities

Support packages

A comprehensive, multi-lingual systemmanual is supplied on CD-ROM with each

laser system when shipped. This manualcontains written and illustrated set-upinformation for each measurement option.

The manual can be installed on your PC andaccessed directly via the Help button withinyour software application, or as a stand-aloneoption, read directly from the CD.

Additional/replacement CDs are availablefree of charge from your local Renishawrepresentative.

2

product

offerings:

calibrationsoftware


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Available datasheets

Renishaw reserves the right to change specifications without notice.

All latest version datasheets are available as pdf documents at www.renishaw.com/rle

L-9904-2346 (RLU10) L-9904-2347 (RLD 90) L-9904-2348 (RLD 0)

L-9904-2350 (RLU20)L-9904-2349 (RCU10) L-9904-2351 (RLD DI)

L-9904-2352 (RPI20) L-9904-2446 (plane mirrorsand mirror mounts)

L-9904-2391 (RLE systemperformance)

23

Available

datasheets

L-9904-2347-04-AData sheet

Forthe fibre optic laserencoder

Renishaws RLEfibre optic laserencoderuses

interferometry to provide high resolution,high linearity

position feedback.

The RLEsystem comprises an RLUlaser unit and one or two

RLDdetector heads. This data sheet describes the RLD90

detector head.

The detector head is the core of the opticalmeasuring system

containing the interferometer, reference optics, fringe detector,

laser shutter and beam steerer.

To complete the interferometer configuration, only one

additionaloptic is required in either plane mirror or

retroreflector based configurations. For easy installation, the

integralrotary beam steerer allows finaladjustments to be

made to optimise beam alignment after the head has been

secured.

The head dissipates negligible power (


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Renishaw plc

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Renishaw worldwideAbout RenishawRenishaw is an established

world leader in engineering

technologies, with a strong

history of innovation in product

development and manufacturing.

Since its formation in 1973, the

company has supplied leading-edge products that increase

process productivity, improve

product quality and deliver cost-

effective automation solutions.

A worldwide network of subsidiary

companies and distributors

provides exceptional service and

support for its customers.

Products include:

Dental CAD/CAMscanning

and milling systems

Encoder systemsfor high

accuracy linear, angle and

rotary position feedback

Laser and ballbar systemsforperformance measurement and

calibration of machines

Medical devicesfor

neurosurgical applications

Probe systems and software

for job set-up, tool setting and

inspection on CNC machine

tools

Raman spectroscopy

systemsfor non-destructive

material analysis

Sensor systems and

softwarefor measurement on

CMMs (co-ordinate measuring

machines) Stylifor CMM and machine tool

probe applications
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Documents

High Precision Laser Interferometer Feedback Systems