Abstract
When measuring the contours of spherical surfaces by direct phase measurement the Twyman-Green interferometer is usually chosen in preference to the Fizeau interferometer. In the Twyman-Green interferometer the phase reference is provided by moving a plane mirror in a direction normal to its surface. In the spherical-wave Fizeau interferometer the reflecting surfaces are spherical and, at the same instant at least, cannot be moved in a direction normal to the surfaces at all points over the optical aperture. It can be shown analytically, however, that for a spherical test surfaces having an N.A. ≲0.8, the error introduced by moving the test surface axially, rather than radially, can be made <λ/100.
© 1980 Optical Society of America
Full Article | PDF ArticleMore Like This
Peter de Groot
Appl. Opt. 34(16) 2856-2863 (1995)
Osami Sasaki, Toshiaki Okamura, and Takanori Nakamura
Appl. Opt. 29(4) 512-515 (1990)
Lin Li, Stanislaw Szapiel, and Claude Delisle
Appl. Opt. 31(7) 866-875 (1992)