Imaging Science and Photochemistry ›› 2017, Vol. 35 ›› Issue (2): 114-119.DOI: 10.7517/j.issn.1674-0475.2017.02.114

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Surface Testing of Primary Mirror in Cassegrain Optics with Computer-generated Hologram

WANG Zhaoming1,2, ZHANG Jiyou1, LI Mengjuan1, YIN Ganghua1, LI Ling1   

  1. 1. Beijing Institute of Space Mechanics and Electricity, Beijing 100076, P. R. China;
    2. Graduate University of China Academy of Space Technology, Beijing 100086, P. R. China
  • Received:2017-01-20 Revised:2017-02-15 Online:2017-03-15 Published:2017-03-15

Abstract:

A binary phase computer-generated hologram(CGH)is designed for precisely testing an aspherical surface in Cassegrain optics. the design principle and is reviewed, Key questions about Optimal Designing of CGH phase function, calculation of Step position and depthare discussed.the concept of virtual glass is introduced for modelling tested surface quickly, the diffraction order is separated by joining coaxial carrier in allusion of center hole of primary mirror in cassegrain system, complexity of phase quantification is simplified, the optimal depth is gotten by numerical simulation,reducing the processing difficulty. design methods are proposed. an instance and simulation is presented and the CGH is produced. root-mean-square(RMS)error obtained from surface testing is 0.018λ,the test result is compared with that of compensatory mirror test meth, which is 0.019λ(RMS).It is demonstrated that the results show a good agreement.The design method is effective,can be used insurface testingof primary mirrorin Cassegrain optics.

Key words: computer-generated holograms, aspheric-surface testing, Cassegrain optical system