Multiple-wavelength interferometry offers a great flexibility in working distance and sensitivity by an appropriate choice of the different wavelengths and it can be operated on rough surfaces. A novel concept of a multiple-wavelength source, using laser diodes, has been developed. It allows to get an absolute calibration of the synthetic wavelengths by electronic beat-frequency measurements. Experimental results show that a calibration of the synthetic wavelength in the millimeter range with an accuracy better than 10^-5 is feasible. A three-wavelength heterodyne interferometer is described and results with 9 μm accuracy on a range of 200 mm are presented. Moreover, a lock-in CCD image sensor has been developed and implemented in our system for applications with non-cooperative targets.

Date Published: 1 September 1996
PDF: 2 pages
Proc. SPIE 2778, 17th Congress of the International Commission for Optics: Optics for Science and New Technology, 2778EJ (1 September 1996); doi: 10.1117/12.2316212

Published in SPIE Proceedings Vol. 2778:
17th Congress of the International Commission for Optics: Optics for Science and New Technology
Joon-Sung Chang; Jai-Hyung Lee; ChangHee Nam, Editor(s)