<title>Precision calibration and systematic error reduction in the long trace profiler</title>

Abstract

The Long Trace Profiler has become the instrument of choice for mirror surface figure test and slope error measurement of 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 FT lens using this technique. The use of a 0.03 arc second resolution theodolite coupled with the sensitivity of the LTP detector system can be used to calibrate 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 (mu) rad rms within whole testing range of the LTP.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.