A Study of Asphereic Surface Tesing

• Main Authors: Haung, Wou Yuan, 黃文源
• Other Authors: Chang, Ming ; Ho, Chwen Shell
• Format: Others
• Language: zh-TW
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/73547422048036993082

碩士 === 中原大學 === 應用物理學系 === 82 === In this study, we tested the asphereic mirror by applying Sub- Nyquist interferometry (SNI) into two-wavelength method and lateral shearing interferometry. SNI is an extension of phase shifting interferometry (PSI) , which can expand the range of asphereic testing of PSI and also increase the precision of phase reconstruction by developing new algorithm of PSI. The major problem in using interferometry for optical asphereic testing is that the resulting interferogram contains too many fringes to analyze. If the spatial frequency of fringes excesses the Nyquistfrequency of detector array, we can''t obtain the phase distribution correctly with PSI. Two- wavelength method has been used to solve this problem, but it will decrease the precision of testing. When the curvature of the asphereic mirror is high, two-wavelength method will not overcome this problem. In this situation, the best way is to introduce lateral shearing interferometry to decrease the number of fringes. In this work, we took the surface characteristics and the Nyquist frencuncy of the detector array into account in the testing and compared the testing ability of PSI and SNI. Finally, we suggest different ways with economic, effective and high precision for various tested objects.