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Proceedings Paper

Modified alignment CGHs for aspheric surface test
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Paper Abstract

Computer Generated Holograms (CGH) for optical test are commonly consisted of one main pattern for testing aspheric surface and some alignment patterns for aligning the interferometer, CGH, and the test optics. To align the CGH plate and the test optics, we designed the alignment CGHs modified from the cat's eye alignment method, which are consisted of a couple of CGH patterns. The incident beam passed through the one part of the alignment CGH pattern is focused onto the one radius position of the test aspheric surface, and is reflected to the other part, and vice versa. This method has several merits compared to the conventional cat's eye alignment method. First, this method can be used in testing optics with a center hole, and the center part of CGH plate can be assigned to the alignment pattern. Second, the alignment pattern becomes a concentric circular arc pattern. The whole CGH patterns including the main pattern and alignment patterns are consisted of only concentric circular fringes. This concentric circular pattern can be easily made by the polar coordinated writer with circular scanning. The required diffraction angle becomes relatively small, so the 1st order diffraction beams instead of the 3rd order diffraction beam can be used as alignment beams, and the visibility can be improved. This alignment method also is more sensitive to the tilt and the lateral shift of the test aspheric surface. Using this alignment pattern, a 200 mm diameter F/0.5 aspheric mirror and a 600 mm diameter F/0.9 mirror were tested.

Paper Details

Date Published: 21 August 2009
PDF: 8 pages
Proc. SPIE 7426, Optical Manufacturing and Testing VIII, 742616 (21 August 2009); doi: 10.1117/12.826659
Show Author Affiliations
Jae-Bong Song, Korea Research Institute of Standards and Science (Korea, Republic of)
Ho-Soon Yang, Korea Research Institute of Standards and Science (Korea, Republic of)
Hyug-Gyo Rhee, Korea Research Institute of Standards and Science (Korea, Republic of)
Yun-Woo Lee, Korea Research Institute of Standards and Science (Korea, Republic of)


Published in SPIE Proceedings Vol. 7426:
Optical Manufacturing and Testing VIII
James H. Burge; Oliver W. Fähnle; Ray Williamson, Editor(s)

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