Two-wavelength interferometer based on a two-color laser-diode array and the second-order correlation technique

A novel two-wavelength interferometer is demonstrated that uses a tunable two-color laser-diode array as the light source. The synthetic wavelength can be easily tuned from 2 to 0.043 mm by variation of the spectral separation between the two wavelengths of the laser output. By using the second-order correlation technique we can directly retrieve the phase change at the synthetic wavelength with no need for sophisticated electronic signal processing.