Approaching sub-50 nanoradian measurements by reducing the saw-tooth deviation of the autocollimator in the Nano-Optic-Measuring Machine

作者：Qian Shinan^*; Geckeler Ralf D; Just Andreas; Idir Mourad; Wu Xuehui

来源：Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment , 2015, 785: 206-212.

DOI：10.1016/j.nima.2015.02.065

• Nano-accuracy metrology
• Optical surface measurements
• Figure
• Synchrotron radiation

Since the development of the Nano-Optic-Measuring Machine (NOM), the accuracy of measuring the profile of an optical surface has been enhanced to the 100-nrad rms level or better. However, to update the accuracy of the NOM system to sub-50 mad rms, the large saw-tooth deviation (269 nrad rms) of an existing electronic autocollimator, the Elcomat 3000/8, must be resolved. We carried out simulations to assess the saw-tooth-like deviation. We developed a method for setting readings to reduce the deviation to sub-50 nrad rms, suitable for testing plane mirrors. With this method, we found that all the tests conducted in a slowly rising section of the saw-tooth show a small deviation of 28.8 to <40 nrad rms. We also developed a dense-measurement method and an integer-period method to lower the saw-tooth deviation during tests of sphere mirrors. Further research is necessary for formulating a precise test for a spherical mirror. We present a series of test results from our experiments that verify the value of the improvements we made.

• 出版日期2015-6-11