Xuefeng ZHAO, Takamasa SUZUKI and Osami SASAKI

Faculty of Engineering, Niigata University, 8050 Ikarashi 2, Niigata 950-2181, Japan

(Received September 6, 2001; Accepted December 5, 2001)

We propose a photothermal phase-modulating laser diode interferometer equipped with a high-speed feedback control system. The CCD camera's shutter-function raises the modulating frequency, which in turn elicits a higher feedback response, thus enabling us to eliminate nearly all external disturbance. With the recent application of a system purpose-built for discriminating between numerous fringe sequences, we have also reduced processing time.

photothermal modulation, laser diode, interferometer, electronic-shutter, integrating-bucket method, sinusoidal phase modulating, feedback control