Nuclear Science and Techniques ›› 2019, Vol. 42 ›› Issue (1): 10103-010103.doi: 10.11889/j.0253-3219.2019.hjs.42.010103

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Position error compensation for large-aperture mirror stitching measurement

Dingxiao LIU1,2,Ming LI1,2,Weifan SHENG1,2()   

  1. 1. Institution of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2018-03-04 Revised:2018-07-28 Online:2019-01-10 Published:2019-01-25
  • Contact: Weifan SHENG E-mail:shengwf@ihep.ac.cn
  • Supported by:
    Supported by National Science Foundation for Young Scientist of China (No.11005123)

Abstract: Background

In order to realize the high precision measurement of large-aperture mirror, a stitching method is established. The position errors between adjacent surfaces affect the stitching results, so compensation algorithm is needed to solve this problem.

Purpose

This study aims to reduce the effect of position errors in stitching measurement by proposing a global optimization algorithm for position error compensation.

Methods

Firstly, the basic theory of stitching measurement technology is applied to dividing the whole test mirror into several parts, each part of the surface should meet the requirement of a single measurement. Then, based on BFGS algorithm, pixel motion and two-dimensional linear interpolation, a stitching method for compensating position error is established. Finally, a ZYGO Fissor interferometer is employed to construct stitching measurement equipment to measure the 120 mm × 20 mm area in reflector by using stitching measurement method.

Results

Compared with full aperture measurement, the peak-valley (PV) and root mean square (RMS) of the height residual achieved by stitching measurement are 8.7 nm and 0.5 nm, respectively.

Conclusions

The experiment result showed that this optimization method can compensate the position error more effectively than the direct stitching method.Key wordsLarge aperture mirror, Interferometry, Optic measurement, Stitching