Haike GUAN, Masahiro YAMAGUCHI and Nagaaki OHYAMA

Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, 4259, Nagatsuta, Midori-ku, Yokohama, 226 Japan

(Received January 31, 1995; Accepted June 8, 1995)

We analyze the influence of error in the measurement of shear value, which is a major source of error in tested results by the lateral shearing interferometer. A novel method is proposed for accurately measuring the shear of this interferometer. By introducing a defocused wavefront and making use of the wavefront slope data of the defocus and the parameters of the interferometer, we can calculate the shear value precisely, with an error less than the sampling interval of the detector. An experiment was conducted to show the effectiveness of the method.

Key words : lateral shearing interferometer, phase reconstruction, shear amount, sampling interval, measurement of shear, defocused wavefront, least squares method