Hideo FURUHASHI, Ryota SUGIYAMA, Yoshiyuki UCHIDA, Kiyofumi MATSUDA¹ and Chander P. GROVER²

Department of Information Network Engineering, Aichi Institute of Technology, 1247 Yachigusa, Yakusa-cho, Toyota, Aichi 470-0392, Japan
¹National Institute of Advanced Industrial Science and Technology, 1-2-1 Namiki, Tsukuba, Ibaraki 305-8564, Japan
²Institute for National Measurement Standards, National Research Council Canada, M36, 1200 Montreal Road, Ottawa ON K1A OR6, Canada

(Received October 4, 2004; Accepted December 9, 2004)

A new optical phase measurement method using a differentiation filter is proposed. The new method uses two images obtained by shifting the filter. This method has an advantage in that non-uniformity of the wavefront intensity does not produce errors. We present herein the theory of the newly proposed method and verify the theory by computer simulation. The effects of non-uniformity of the wavefront intensity, noise, and bias shifting length for errors are discussed. The system has been demonstrated for a plane wave and a spherical wave. For the proposed method, although the number of errors due to noise increases, the number of errors due to non-uniformity decreases. Therefore, the proposed method is useful for the phase measurement of a wavefront for which the intensity is not uniform. In addition, it improves the accuracy of the phase measurement system using a differentiation filter.

Key words: phase measurement, optical differentiation, phase shifting, wavefront measurement