[OPTICAL REVIEW Vol. 5, No. 2 (1998) 115-118]

Si Micromachined Pinhole and Surrounding Photodiode for Incident Beam Position Sensing and Automatic Alignment

Minoru SASAKI, Yuji ARAI and Kazuhiro HANE

Department of Mechatronics and Precision Engineering, Tohoku University, Sendai, 980-8579 Japan

(Received January 12, 1998; Accepted February 3, 1998)

The spatial filter of a Si micromachined pinhole integrated with photodiodes is fabricated. The photodiode cells placed around the center pinhole can detect the relative position between the incident beam spot and the pinhole. The position signal obtained from a two or four cell type photodiode and position sensitive detector show the sensitivity even when the beam spot is near the center pinhole. Combined with the feedback control of the shape memory alloy actuator based on the obtained position signal, the pinhole is aligned automatically.

Key words : Si micromachining, pinhole, photodiode, shape memory alloy, spatial filter, automatic alignment