NEW DIODE-LASER LIGHT-SOURCE FOR ABSOLUTE RANGING 2-WAVELENGTH INTERFEROMETRY

Two-wavelength interferometry a well-known technique to enlarge the am biguity range of conventional interferometric ranging systems. The mai n problem with this technique is that the light source used must gener ate the desired wavelengths, which must be adaptable to the actual app lication. Those wavelengths have to be known precisely and must be sta bilized to the desired accuracy. Because of the lack of an inexpensive , compact, and intense light source that provides for the desired wave lengths, two-wavelength ranging systems previously have been without t echnical importance. We present a new light source for this purpose, w hich is based on stabilized semiconductor lasers. Our system generates two stabilized wavelengths in the submicrometer range and a synthetic wavelength in the submillimeter range, respectively. In the case of t he submillimeter wavelength, both laser wavelengths are locked to the same Fabry-Perot resonator. This method, previously known in principle , is used for semiconductor lasers for the first time.