Download - Laser Trackers: Testing and Standards
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Dr. Steven D. PhillipsDr. Steven D. PhillipsDimensional Metrology Program ManagerDimensional Metrology Program Manager
National Institute of Standards and TechnologyNational Institute of Standards and Technology
Laser Trackers: Laser Trackers: Testing and StandardsTesting and Standards
Large Scale MetrologistsLarge Scale MetrologistsBalaBala MuralikrishnanMuralikrishnan
Dan SawyerDan SawyerChris BlackburnChris BlackburnBruce BorchardtBruce Borchardt
Tyler Tyler EstlerEstlerCraig Craig ShakarjiShakarji
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OverviewOverview
Briefly about Laser TrackersBriefly about Laser Trackers B89.4.19 Standard & Tests ResultsB89.4.19 Standard & Tests Results VDI/VDE 2617 Draft Standard VDI/VDE 2617 Draft Standard Final RemarksFinal Remarks
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XY
Z
x
y
z
Horizontal Axis
R
V
e
r
t
i
c
a
l
A
x
i
s
Laser Trackers:Laser Trackers:Coordinate Measuring Machines Coordinate Measuring Machines Using Spherical CoordinatesUsing Spherical Coordinates
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Laser Trackers:Laser Trackers:Optics Link the Workpiece & CMM Optics Link the Workpiece & CMM
Allows large measurement volumesBring the tracker to the workpieceLower capital costs than large conventional CMMsFactory can be reconfigured
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Laser Trackers:Laser Trackers:Type of Ranging Systems Type of Ranging Systems
Laser Radar Non cooperative target OK
Moderate accuracy
More expensive
HeNe Interferometer Very High Accuracy
Do NOT break beam during measurement
Requires cooperative target, e.g. retroreflector
Absolute Distance Measuring System Good Accuracy
Can break beam & measure directly to targets
Requires cooperative target, e.g. retroreflector
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ASME B89.4.19 Laser Tracker StandardASME B89.4.19 Laser Tracker Standard
Designed to Test Cooperative Target SystemsDesigned to Test Cooperative Target Systems Focused on Manufacturing (Indoor) EnvironmentFocused on Manufacturing (Indoor) Environment Tests Ranging and Volumetric PerformanceTests Ranging and Volumetric Performance Does not address:Does not address:
Outdoor EnvironmentsOutdoor Environments Rain; Fog Rain; Fog
NonCooperativeNonCooperative Targets: Targets: Concrete; Wood; DirtConcrete; Wood; Dirt
Dynamic effectsDynamic effects Motion in the field of viewMotion in the field of view
Available At www.ASME.org
(search on B89.4.19)
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Ranging Test using 6 Calibrated LengthsRanging Test using 6 Calibrated Lengths
L1 L2
L3 L4
Target Nests
Nest b
Nest a
h
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1D Cooperative Target Range Facility1D Cooperative Target Range FacilityNIST System ConfigurationNIST System Configuration
Interferometer
Instrument under test
Carriage can accommodate a variety of targets
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11--D Cooperative Target Range FacilityD Cooperative Target Range Facility
Reference retroreflector
Target retroreflector
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11--D Cooperative Target Range FacilityD Cooperative Target Range Facility
Range: 60 m (200 feet)
Temperature: 20 0.2 CSensors:
U(T) = 0.01 C, spaced @ 10 mU(P) = 20 Pa
U(RH) = 1 % RH
U(L) = 5 m + 3 10-7
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11--D Cooperative Target Range FacilityD Cooperative Target Range FacilityRanging test of an IFM tracker showing vacuum wavelength errorRanging test of an IFM tracker showing vacuum wavelength error
0 1 0 2 0 3 0 4 0 5 0 6 0- 0 . 0 7
- 0 . 0 6
- 0 . 0 5
- 0 . 0 4
- 0 . 0 3
- 0 . 0 2
- 0 . 0 1
0
0 . 0 1
0 . 0 2
D is p la c e m e n t ( m )
E
r
r
o
r
(
m
m
)
R u n # 1C o r r e c te d r u n # 1R u n # 2C o r r e c te d r u n # 2E r r o r d u e to i n c o r r e c t w a v e l e n g th
1 x 10-6
Wavelength in instrument = 632.990400 nmCalibrated wavelength (NIST) = 632.991061 nm Difference = 0.6 10-3 nmRelative length error = 0.6 10-3 nm / 633 nm = 1 10-6
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11--D Cooperative Target Range FacilityD Cooperative Target Range Facility
0 5 1 0 1 5 2 0 2 5 3 0 3 5-0 . 0 4
-0 . 0 3
-0 . 0 2
-0 . 0 1
0
0 . 0 1
0 . 0 2
0 . 0 3
0 . 0 4
D is p la c e m e n t (m )
E
r
r
o
r
(
m
m
)
R u n # 1R u n # 2R u n # 3M P E
Ranging test of an IFM tracker; passing specificationsRanging test of an IFM tracker; passing specifications
+MPE
MPE
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11--D Cooperative Target Range FacilityD Cooperative Target Range FacilityRanging test of an ADM tracker passing specificationsRanging test of an ADM tracker passing specifications
0 1 0 2 0 3 0 4 0 5 0 6 0-0 . 0 8
-0 . 0 6
-0 . 0 4
-0 . 0 2
0
0 . 0 2
0 . 0 4
0 . 0 6
0 . 0 8
D is p la c e m e n t (m )
E
r
r
o
r
(
m
m
)
R u n # 1R u n # 2R u n # 3M P E
+MPE
MPE
Significantly morepoints sampled than required by B89.4.19
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Ranging System Test on ADM #2-2
0.000
0.100
0.200
0.300
0.400
0 5 10 15 20 25
Length, m
E
r
r
o
r
,
m
m
11--D Cooperative Target Range FacilityD Cooperative Target Range FacilityRanging test of an ADM tracker showing complex Ranging test of an ADM tracker showing complex range errors before compensation & small errors range errors before compensation & small errors after compensationafter compensation
Before Cal
After Cal
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Volumetric System Tests:Volumetric System Tests:Check OpticalCheck Optical--Mechanical AlignmentsMechanical Alignments
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Volumetric System TestsVolumetric System Tests
b
a
A
D h
Target stands
Standing axis
a
bh
D
Target nestsA
Standing axis
Horizontal Positions Vertical Positions
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Volumetric System TestsVolumetric System Tests
Right Diagonal Position Left Diagonal Position
45 degrees0.7A
h
a
b Target nests
D
0.7A
Standing axis A
45 degrees
h
0.7A
D
a
b
Target nests
0.7A
Standing axis
A
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Large Scale Volumetric Test FacilityLarge Scale Volumetric Test Facility
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B89.4.19 Volumetric System TestsB89.4.19 Volumetric System Tests(Horizontal Tests)(Horizontal Tests)
Back to back target SMRs
LaserInterferometer
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B89.4.19 Volumetric System TestsB89.4.19 Volumetric System Tests(Horizontal Tests (Horizontal Tests Physical Artifact)Physical Artifact)
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B89.4.19 Volumetric System TestsB89.4.19 Volumetric System Tests(Diagonal Tests)(Diagonal Tests)
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Volumetric Performance Test on ADM #6
-0.15
-0.10
-0.05
0.00
0.05
0.10
0.15
E
r
r
o
r
,
m
m
1st reading
2nd reading
3rd reading
+MPE
-MPE
Vertical Right DiagonalHorizontal Left Diagonal User
All readings in ADM mode unless otherw ise indicated
3m
6m
3m
6m
3m
6m
3m
6m
1m
3
m
5
m
0 9 0 18 0 2 7 0 0 9 0 18 0 2 7 0 0 9 0 18 0 2 7 0 0 9 0 18 0 2 7 0 0 9 0 18 0 2 7 0 0 9 0 18 0 2 7 0 0 9 0 18 0 2 7 0 0 9 0 18 0 2 7 0
B89.4.19 Volumetric System TestsB89.4.19 Volumetric System TestsVolumetric test of an ADM, passing MPE specificationsVolumetric test of an ADM, passing MPE specifications
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B89.4.19 Volumetric System TestsB89.4.19 Volumetric System Tests
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
E
r
r
o
r
(
m
m
)
1st reading2nd reading3rd readingMPE
3m 6m 3m 6m 3m 6m 3m 6m0 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270
3 m 6 m
3 m6 m
3 m6 m
3 m6 m
1 m
Horizontal Vertical Right Diagonal Left Diagonal
Volumetric test of an IFM tracker, failing MPE specificationsVolumetric test of an IFM tracker, failing MPE specifications
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B89.4.19 Volumetric System TestsB89.4.19 Volumetric System Tests
H o r 3 m
H o r 6 m
V e r 3 m
V e r 6 m
R D 3 m
R D 6 m
L D 3 m
L D 6 m
0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0
E
r
r
o
r
Beam Tilt (X)
Beam Tilt (Y)
Horizontal Angle Encoder Eccentricity (Y)
Horizontal Angle Encoder Eccentricity (X)
0 5 1 0 1 5 2 0 2 5 3 0 3 5-0 .4
-0 .2
0
0 .2
0 .4
E
r
r
o
r
(
m
m
)
M e a s u re d e rro rsS im u la te d e rro rs
H o r 3 m
H o r 6 m
V e r 3 m
V e r 6 m
R D 3 m
R D 6 m
L D 3 m
L D 6 m
0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0
(0 5 1 0 1 5 2 0 2 5 3 0 3 5
-0 .4
-0 .2
0
0 .2
0 .4
E
r
r
o
r
(
m
m
)
M e a s u re d e rro rsS im u la te d e rro rs
0 5 1 0 1 5 2 0 2 5 3 0 3 5-0 .4
-0 .2
0
0 .2
0 .4
E
r
r
o
r
(
m
m
)
M e a s u re d e rro rsS im u la te d e rro rs
H o r 3 m
H o r 6 m
V e r 3 m
V e r 6 m
R D 3 m
R D 6 m
L D 3 m
L D 6 m
0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0 0 9 0 1 8 0 2 7 0
(
Simulated and actual errors for the volumetric testSimulated and actual errors for the volumetric test
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B89.4.19 Two Face TestB89.4.19 Two Face Test
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B89.4.19 Two Face TestsB89.4.19 Two Face Tests
0
0.05
0.1
E
r
r
o
r
(
m
m
)
1st reading2nd reading3rd readingMPE
0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270
D minimum 3 m 6 m
Low Mid High Low Mid High Low Mid High
Two face test of an ADM tracker, passing MPE specificationsTwo face test of an ADM tracker, passing MPE specifications
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B89.4.19 B89.4.19 Two Face Two Face TestsTests
0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270
D minimum 3 m 6 m
Low Mid High Low Mid High Low Mid High
0
0.1
0.2
0.3
0.4
0.5
E
r
r
o
r
(
m
m
)
1st reading2nd reading3rd readingMPE
Two face test of an ADM tracker, failing MPE specificationsTwo face test of an ADM tracker, failing MPE specifications
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B89.4.19 B89.4.19 Two Face Two Face TestsTests
0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270 0 90 180 270
D minimum 3 m 6 m
Low Mid High Low Mid High Low Mid High (Kz)
E
r
r
o
r
Horizontal angle encoder eccentricity (X) Horizontal angle encoder eccentricity (Y)
0 5 10 15 20 25 30 350
0.1
0.2
0.3
0.4
0.5
E
r
r
o
r
(
m
m
)
Measured errorsSimulated errors
Simulated and actual errors for the two face testSimulated and actual errors for the two face test
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VDI / VDE Tracker Draft
Use a measurement volume 3 x 6 x 10 m with multiple calibrated lengths created via distances between fixed mounts
Evaluate the observed errors against the manufacture's MPE specification
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VDI / VDE Tracker Draft
Projecting the lengths onto a wall and moving the tracker makes the set up easier
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VDI / VDE Tracker Draft
Probe Test to check the SMR size and form
Similar to the ISO CMM probe test
25 measurement points on a calibrated test sphere:
Report: Size and Form error
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Final Thoughts On Laser TrackersFinal Thoughts On Laser Trackers Large Measurement Volumes; range Large Measurement Volumes; range > 30 m> 30 m
Very Low Cost Compared to Large CMMsVery Low Cost Compared to Large CMMs
Portable, Bring the Tracker to the WorkpiecePortable, Bring the Tracker to the Workpiece Allows Factory Floor to be Easily ReconfiguredAllows Factory Floor to be Easily Reconfigured
ADM Systems Yield Direct MeasurementsADM Systems Yield Direct Measurements No Issue with Beam Breakage or No Issue with Beam Breakage or WalkoutWalkout
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Standardized Tracker Tests AllowTracker Tests Allow For manufacturers to specify performance For users to test performance Detection of most tracker errors
Test results that are metrologically traceable (e.g., per ASME B89.7.5)
Final Thoughts On Laser Trackers
ISO Working Draft for Trackers Combines B89 & VDI work Improves sensitivity to errors Includes SMR probe test Includes workpiece CTE compensation test
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Laser Trackers: Laser Trackers: Testing and StandardsTesting and Standards
Q & AQ & A
Disclaimer:
Data on commercial products are only provided for the sake of describing experimental results. NIST does not endorse or recommend any commercial products or imply that this equipment is the best for any particular application.