[OPTICAL REVIEW Vol. 4, No. 5 (1997) 588-592]

High Accuracy Phase Measurement in Phase-Shifting Speckle Interferometry*

Yoshihiro OSHIDA,1 Yoshihisa IWAHASHI2 and Koichi IWATA3

1Nara National College of Technology, 22, Yata-cho, Yamatokoriyama, Nara, 639-11 Japan, 2Junior College, Osaka Sangyo University, 3-1-1, Nakagaito, Daito, Osaka, 574 Japan, 3College of Engineering, Osaka Prefecture University, 1-1, Gakuen-cho, Sakai, Osaka, 593 Japan

(Received August 26, 1996; Accepted June 10, 1997)

A method for accurately measuring information about the deformation of a rough surface object using a phase-shifting speckle interferometer with a television camera and a computer is considered. In this case, the intensity change of the speckle by phase-shifting varies randomly in space because of the statistical property of the speckle. Then, at points with small intensity change, the accuracy of the phase measurement is affected significantly by the quantization error of an analog to digital converter for data recording. To improve the accuracy, the statistical property of the interference speckle must be clarified. This is done theoretically and experimentally, and the experimental results show that higher measurement accuracy can be attained by selecting large amplitude points.

Key words : phase-shifting method, speckle interferometer, phase measurement, statistical property of speckle, quantization error

*Presented at 1996 International Workshop on Interferometry (IWI '96), August 27-29, Saitama, Japan.