Frequency-comb-referenced two-wavelength source for absolute distance measurement

We propose a new tunable laser source concept for multiple-wavelength interferometry, offering an unprecedented large choice of synthetic wavelengths with a relative uncertainty better than 10⁻¹¹ in vacuum. Two lasers are frequency stabilized over a wide range of frequency intervals defined by the frequency comb generated by a mode-locked fiber laser. In addition, we present experimental results demonstrating the generation of a 90 μm synthetic wavelength calibrated with an accuracy better than 0.2 parts in 10⁶. With this synthetic wavelength we can resolve one optical wavelength, which opens the way to absolute distance measurement with nanometer accuracy.