[OPTICAL REVIEW Vol. 7, No. 2 (2000) 158-163]

Phase-Shifting Fringe Analysis for Laser Diode Wavelength-Scanning Interferometer

Jun-ichi KATO and Ichirou YAMAGUCHI

Optical Engineering Laboratory, RIKEN (The Institute of Physical and Chemical Research), 2-1, Hirosawa, Wako, Saitama, 351-0198 Japan

(Received November 8, 1999; Accepted December 14, 1999)

A method for analyzing the fringe patterns obtained from a wavelength-scanning interferometer is proposed. It is based on phase retrieval with the phase-shifting method and derivation of its slope along the wave number axis. The accuracy and the error sources are estimated by experiments, in which a laser diode under small wavelength-modulation (~95 pm) is used as the light source. A conventional piezoelectric phase shifter was used for a phase shifter. This technique can be applied to profile measurement of stepped objects located across the zero-path position.

Key words : wavelength scanning interferometry, profile measurement, laser diode, phase-shifting technique, stepped object, mass fractal, surface fractal, combined fractal, self-similarity, power law, fractal dimension