Upload
others
View
9
Download
0
Embed Size (px)
Citation preview
Optical 3D micro coordinate measurement | Form & roughness
The advantages of Optical 3D Surface Metrology
Measurement
on AM Surfaces
Optical 3D micro coordinate measurement | Form & roughness
Agenda
» Traditional measurement methods of surface measurement
» Optical methods
» Focus Variation as a measuring principal
Optical 3D micro coordinate measurement | Form & roughness
Preview
➢ The measurement of complex surfaces such as AM surfaces presents
problems when it comes to surface finish measurement
➢ Growing need to build the product with the finished surface
➢ The surface to be measured is generally not homogenous and can be very
rough in nature and often will have a geometric form/free shape
➢ Point and line based measurements do NOT reflect the true surface but only
a line on the surface
➢ This leads to a requirement for an area based measurement
Optical 3D micro coordinate measurement | Form & roughness
Traditional Mechanical Contact Instruments
The basis of the technique is to record the
mechanical movement of a precision stylus as it is
scanned across the surface to be measured
Many Different Stylus
& Probe Designs
available Today
including hand held
devices, providing a
2D measurement
Optical 3D micro coordinate measurement | Form & roughness
Stylus
Beam
Knife Edge Pivots
)
Coil
Coil
Simple Contact Measurement
Surface to be Measured
Optical 3D micro coordinate measurement | Form & roughness
Stylus Tip
B
A
Profile produced by Stylus –
Smoothing the Surface B
A
Reproducing the Surface – Limitations / Smoothing
Reproducing The Surface
Actual surface
being measured
Optical 3D micro coordinate measurement | Form & roughness
3D Measurements with Stylus Instruments
Y Axis Incremental Movement
X Traverse Direction
A map is built up of a number of X traces in Y (up to ~250)
Disadvantages:
Takes a long time to produce the 3D map (~30min or much longer)
Subject to drift depending on environment
Need to ensure the X start position of each trace is the same
Optical 3D micro coordinate measurement | Form & roughness
Variances in Measurement with Profile Measurement (on an Optical Device» Rough “AM” Type
Surface
1.16µm Ra
1.36µm Ra
0.99µm Ra
Optical 3D micro coordinate measurement | Form & roughness
Benefits of area based measurementsWHY OPTICAL 3D METROLOGY?
»
=
≠Area
Profile
In some cases profile based measurements
do not give enough information
Optical 3D micro coordinate measurement | Form & roughness
Area Versus Profile Measurement
Extracted profile:
Same profile butcompletely different surface structure
- Profile Measurement gives only limited information
- You have to know your surface and what you are doing
- Area Measurement can help obtaining more reliable results
Optical 3D micro coordinate measurement | Form & roughness
Summary of Tactile Measurements
➢ Tactile measurements provide information about the line, NOT the surface
➢ There can be large variations in line measurement results across the surface,
which one is the correct answer? – or do you move it until the correct answer
is found
➢ Very subjective and user affected
➢ Stylus smoothing of surface greatly affects the results
Optical 3D micro coordinate measurement | Form & roughness
Optical Surface Measurement
Optical Techniques offer many advantages over tactile probing.
➢ They are non contact, do NOT cause surface deformation or damage
➢ They allow easy measurement of both line based (R values) and area
based (S values) measurement
➢ With line based they allow correct positioning of the profile line
➢ They allow both form and finish to be measured on the same surface
➢ The results are NOT subject to “stylus smoothing”
➢ There are 2 main types of instrument
Optical 3D micro coordinate measurement | Form & roughness
1) Interferometry
➢ Interferometry is a family of techniques in which waves are superimposed
causing an interference pattern to extract surface information, commonly
used in science and industry for the measurement of small surface
variations
➢ These techniques are ideal for the measurement of smooth and flat
surfaces (these are typically not AM surfaces)
➢ They would not measure slopes greater than 30 degrees
➢ They are subject to environmental variations and results need to be
“interpreted” rather than “read”
Optical 3D micro coordinate measurement | Form & roughness
White Light Interferometer
The Reference and Test beams must travel equal distances
from their point of creation in order for interference to be created from
the flat reference mirror
CCD
Test Beam
Reference Beam
Test Beam Length = Reference Beam Length (Optical
Path Difference (OPD) = 0)
Optical 3D micro coordinate measurement | Form & roughness
WLI Slope Limitations
Sample is not flat
WLI use a flat reference so can only measure low sloping surfaces
Sample is steppedSample is tilted
Higher Magnification Lenses (required for roughness
measurement) can only measure up to 30 degrees and
have a small field of view
Optical 3D micro coordinate measurement | Form & roughness
2) Focus Variation
➢ Focus variation is a method to calculate a sharp optical 3D datasets, from
Optics with a limited depth of field on which measurements are made
➢ This technique is ideal for the measurement of surfaces from submicron
to millimetres and allows measurement of line AND area based
measurement
➢ It is possible to measure slopes up to 870 and rough and sculptured
surfaces
➢ The technique is very robust and NOT generally affected by environmental
variations. Results can be easily obtained and “read”.
➢ The ideal solution for AM surfaces
Optical 3D micro coordinate measurement | Form & roughness
How Focus Variation Works“Simple“ Explanation
9 m
DOFDOF
5 m
5 m 9 m5 m 9 m
Optical 3D micro coordinate measurement | Form & roughness
Focus-Variation Coaxial Illumination
The specimen is
illuminated with modulated
light
The light is reflected by
the specimen and
projected on to a digital
sensor in the precision
optic
As the distance
between specimen and
objective is varied the
change of sharpness
is measured
Optical 3D micro coordinate measurement | Form & roughness
Patented* illumination Focus Variation Ring Light Illumination
objective &
concentrator
*patent pending
The ring light helps to measure
High Angled Surfaces
Super low reflective surfaces
Optical 3D micro coordinate measurement | Form & roughness
Optical Measurement Complex Structures Measurement of Very Rough Surfaces
• 3D Surface datasets can be joined together with image stitching
• Surface over lap, true colour and localised features all contribute to the stitching algorithm pulling the
data together
InfiniteFocus Optical 3D Measurement
3D Sensor Objective: Alicona 50x
Optical 3D micro coordinate measurement | Form & roughness
Results from Area Based (Functional) Parameters
Optical 3D micro coordinate measurement | Form & roughness
Results from Area Based (Functional) Parameters
Optical 3D micro coordinate measurement | Form & roughness
Results from Area Based (Functional) Parameters
Vmp 0.03Peak material volume of the topographic surface (ml/m²)
Vmc 0.89Core material volume of the topographic surface (ml/m²)
Vvc 1.04Core void volume of the surface (ml/m²)
Vvv 0.17Valley void volume of the surface (ml/m²)Vvc/Vmc 1.17Ratio of Vvc parameter to Vmc parameter
Optical 3D micro coordinate measurement | Form & roughness
Alicona Measurement Instruments
Optical 3D micro coordinate measurement | Form & roughness
Summary of Focus Variation on AM surfaces
» Provide full details of a surface – not just a line
» Provide “Texture” information on the surface
» Not subject to operator variances – so reduces operator influence of the measurement
» Robust and Repeatable
Optical 3D micro coordinate measurement | Form & roughness
EdgeMasterX
InfiniteFocus G5
IF-SensorR25
ToolCobot
IF-ProfilerInfiniteFocusSL
EdgeMaster
PortableRL
µCMMCompactCobot
DiscCobot
AliconaMeasurement solutions
Optical 3D micro coordinate measurement | Form & roughness
27
• IF is a Focus Variation based
measurement instrument that
combines
– An high powered optical
imaging system
– Optical surface profiler
Alicona Infinite Focus
Measurements:
– Non-destructive
– Accurate and quantitative 3-D surface characterisation
– Fast
– Capable of measuring a wide range of materials and surfaces
Optical 3D micro coordinate measurement | Form & roughness
Measure 87 Degree SlopesMachine Tool Tip Cutting Edge Measurements
Positive Bevel Negative Bevel Edge Roundness
Chipping Basket Arch
Type 1
Type 2
Type 3
Type 4
Type 5
Optical 3D micro coordinate measurement | Form & roughness
29Critical Dimensions
Measure:
Heights, Sizes,
Angles, Volume,
Form, etc.
Optical 3D micro coordinate measurement | Form & roughness
Technology: Focus-Variation
Contouring Roughness
&
Optical 3D micro coordinate measurement | Form & roughness
IF - Technical Specifications
Optical 3D-surface metrology based on a colour focus sensor
InfiniteFocus G5 InfiniteFocus SL
Vertical resolution >10nm >20nm
Lateral resolution >440nm >640nm
Scan height <22mm
<36mm (with new HX lens)
<25mm
Scan area 200mm x 200mm 50mm x 50mm
Optical 3D micro coordinate measurement | Form & roughness
Application independent
» Tool industry » Micro precision manufacturing
» Medical technology and pharmaceutics
» Injection moulding » Automotive industry » Aerospace and aeronautics
Optical 3D micro coordinate measurement | Form & roughness
Thank You for Listening