Wavelength scanning interferometry using multiple light sources.

A novel sensing method is proposed for wavelength scanning interferometry using multiple tunable light sources. As it is well known, a deterioration of depth resolution usually occurs when multiple phase intervals, corresponding to the multiple tunable light sources, are used for distance measurement purposes. It is shown here, that it is possible to regain depth resolution characteristics of a complete scan by means of a temporal phase unwrapping extrapolation method. With the proposed method, the resulting phase differences among multiple phase intervals can be successfully unwrapped to find out the intermediate phase. This effectively allows the application of whole-scan phase sensing for distance measurement using reduced scanning intervals, increased speed, and improved depth detection.