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Appendix A Operating Specifications
Table A-7. Straightness measurement specifications
Characteristic
Straightness measurement
range
Straightness measurement
1
accuracy
Optical reference accuracy
for short range optics
Optical reference accuracy
for long range optics
Straightness measurement
resolution for short-range
optics
Straightness measurement
resolution for long-range
optics
2
Axial separation
1
Straightness measurement accuracy is analogous to the traditional straightedge and indicator method of
measuring straightness.
Optical reference accuracy, listed in Table A-7, corresponds to straightedge accuracy. Optical reference
accuracy can be eliminated by using straightedge (mirror) reversal techniques.
Measurement accuracy corresponds to the indicator accuracy. It depends on the optics being used, and the
temperature range. See table A-8 or A-9.
2
Axial separation is the distance between the interferometer and the reflector with proper alignment and air
temperature between 15° and 25° C (59° and 77° F).
A-8
Specification
± 1.5 mm (0.059 in)
Overall accuracy = Optical reference accuracy
+ Measurement accuracy
2
± 0.15 M
μm where M is the distance the
1
moving optic has traveled in meters;
2
± 0.5 F
μin where F is the distance the
moving optic has traveled in feet
2
± 0.015 M
μm where M is the distance the
1
moving optic has traveled in meters; ± 0.05
2
F
μin where F is the distance the moving
optic has traveled in feet
0.01 μm (0.4 μin)
0.1 μm (4 μin)
0.1 to 3 m (4 to 120 in) with short range optics,
1 to 30 m (3 to 100 ft) with long range optics
Measurements Reference Guide
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