Precision calibration and systematic error reduction in the long trace profiler

The long trace profiler (LTP) has become the instrument of choice for surface figure testing and slope error measurement of mirrors used for synchrotron radiation and x-ray astronomy optics. In order to achieve highly accurate measurements with the LTP, systematic errors need to be reduced by precis...

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Bibliographic Details
Published in:Optical Engineering 2000-01, Vol.39 (1), p.304-310
Main Authors: Qian, Shinan, Sostero, Giovanni, Takacs, Peter Z
Format: Article
Language:English
Subjects:
accuracy
angle calibration
CALIBRATION
ERRORS
EXPERIMENTAL DATA
focal error
INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
long trace profiler
MEASURING INSTRUMENTS
MIRRORS
OPTICAL EQUIPMENT
system error
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Summary:The long trace profiler (LTP) has become the instrument of choice for surface figure testing and slope error measurement of mirrors used for synchrotron radiation and x-ray astronomy optics. In order to achieve highly accurate measurements with the LTP, systematic errors need to be reduced by precise angle calibration and accurate focal plane position adjustment. A self-scanning method is presented to adjust the focal plane position of the detector with high precision by use of a pentaprism scanning technique. The focal plane position can be set to better than 0.25 mm for a 1250-mm-focal-length Fourier-transform lens using this technique. The use of a 0.03-arcsec-resolution theodolite combined with the sensitivity of the LTP detector system can be used to calibrate the angular linearity error very precisely. Some suggestions are introduced for reducing the system error. With these precision calibration techniques, accuracy in the measurement of figure and slope error on meter-long mirrors is now at a level of about 1 rad rms over the whole testing range of the LTP. ©
ISSN:0091-3286
1560-2303
DOI:10.1117/1.602364