Two-wavelength interferometry is a well known technique to enlarge the ambiguity range of conventional interferometric systems without loss of resolution. Two laser emission lines with a spectral distance of a few nm form a so-called synthetic wavelength, which is used for absolute ranging. Due to the lack of an inexpensive and compact light source providing for a tunable synthetic wavelength, two-wavelength interferometry has been without technical importance up to now. We present a new light source for absolute ranging two-wavelength interferometry based on stabilized semiconductor lasers. Two semiconductor lasers operating at different wavelengths are prestabilized concerning their chip temperatures and their injection currents. Then the generated synthetic wavelength is stabilized directly by a Fabry Perot resonator. The stability and the performance of the synthetic wavelength control is shown.
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