[OPTICAL REVIEW Vol. 13, No. 2 (2006) 53-63]
© 2006 The Optical Society of Japan

Laser-Diode Phase-Shifting Joint-Transform Correlator with Multiple-Object Recognition

Takeshi TAKAHASHI* and Yukihiro ISHII1†

Department of Electronic System Engineering, University of Industrial Technology, 4-1-1 Hashimotodai, Sagamihara, Kanagawa 229-1196, Japan
1Department of Applied Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan

(Received November 14, 2005; Accepted December 28, 2005)

A joint-transform phase correlation is made by an extracted phase from the joint power spectrum using a phase-shifting Mach–Zehnder interferometer with a wavelength-shifted laser diode (LD), and then by numerically Fourier-transforming a measured phase. The algorithm in six steps is insensitive to the power changes in an LD. The phase correlator gives the best discrimination performance. Discriminative multiple-object recognition is performed with no intermodulation noise and artifact noise-free correlation by arranging the multiple objects in a regularly equal-spaced array. The experimental and numerical results are shown.

Key words: laser diode, wavelength tunability, phase-shifting interferometer, joint-transform phase correlator, multiple-object recognition

*E-mail address: take@uitec.ac.jp
E-mail address: y.ishii@rs.kagu.tus.ac.jp