Frequency comb-based depth imaging assisted by a low-coherence optical interferometer

We proposed a system composed of a frequency comb interferometer and an optical interferometer of an optical frequency comb mode-locked femtosecond laser to measure the profile of an object. The profile of the object was fast measured by the frequency comb interferometer by means of a single pixel camera. Because of the larger size of the sampling point of the masks integrated in the single pixel camera and the long wavelength of the radio frequency, the profile of the object obtained in this step has low spatial resolution. Since then the measurement was carried out by the optical interferometer using Michelson's setup. The very accurate and high lateral and axial resolution object's profile can be partly observed by using low-coherence interference chromatic phase shifting technique. Resultantly, the combination of the frequency comb interferometer and the optical interferometer by matching the relative phases allowed measuring the object's profile with meter order depth and nano-scale resolution. Employing the proposed system, the whole object or parts of the object with very high resolution can be determined and the measurement time was reduced, dramatically.