A chopper wheel, a bicell photodetector, and an electronic phase detector are used in a mechanization of the Foucault optical test to obtain a linear focus error voltage for an isolated point image. Geometrical and diffraction analyses of the technique are included which show the sensitivity of the technique to aberrations of higher order than focus.
© 1983 Optical Society of America
David G. Kocher, "Automated Foucault test for focus sensing," Appl. Opt. 22, 1887-1892 (1983)