The traditional optical test for an off-axis segment of a parabolic mirror utilizes an autocollimation flat and requires considerable test-bay space. We describe several other test configurations that will minimize space requirements. One method involves a null corrector, and three others require no auxiliary test optics. Combinations of the methods described will be useful in providing full independent evaluation of the figure of the segment under test.
Aden B. Meinel,
Marjorie P. Meinel,
"Optical Testing Of Off-Axis Parabolic Segments Without Auxiliary Optical Elements," Optical Engineering 28(1), 280171 (1 January 1989). http://dx.doi.org/10.1117/12.7976904