The entire process of designing the test setup with a computer-generated hologram (CGH), fabricating the CGH with a laser direct writing system and performing the CGH-null test of an asphere will be described in detail. New considerations in designing the null corrector with calculating CGH's phase function, filtering off unwanted diffraction orders and aligning CGH to the interferometer are discussed. A laser writing machine is used to fabricate designing patterns onto plane substrate and substrate figure error, pattern distortion, etching and duty cycle variations that influence the reconstructed wavefront are quantitatively analyzed in theory and corresponding error equations are obtained. The CGH used for measuring a paraboloid mirror is designed and fabricated. Experimental results of interferometric CGH-null test are presented.

Date Published: 12 March 2008
PDF: 8 pages
Proc. SPIE 6624, International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing, 66240K (12 March 2008); doi: 10.1117/12.791080

Published in SPIE Proceedings Vol. 6624:
International Symposium on Photoelectronic Detection and Imaging 2007: Optoelectronic System Design, Manufacturing, and Testing
Liwei Zhou, Editor(s)