STABILIZED 3-WAVELENGTH SOURCE CALIBRATED BY ELECTRONIC MEANS FOR HIGH-ACCURACY ABSOLUTE DISTANCE MEASUREMENT

Multiple-wavelength interferometry offers great flexibility in working distance and sensitivity by permitting an appropriate choice of the d ifferent wavelengths used, and it can be operated on rough surfaces. T he accuracy of distance measurement with this approach depends on the stability and the calibration of the different wavelengths. A novel co ncept of a multiple-wavelength source that uses laser diodes has been developed. It allows one to obtain an absolute calibration of the synt hetic wavelengths by the use of electronic beat-frequency measurements . Experimental results show that a calibration of the synthetic wavele ngth in the millimeter range with an accuracy of better than 10(-5) is feasible. (C) 1996 Optical Society of America