Fiber optic velocity interferometer with very short coherence length light source

A novel fiber optic velocity interferometer for velocity measurements of moving surfaces has been developed and tested. The interferometer is based on optical fibers or fiber coupled components only and therefore is compact, portable, easy to align, and enables measurements in hard to reach locations. It also does not require a source of long coherence length (only a few wavelengths, regardless of the optical path difference or the surface displacement). This interferometer removes the directional ambiguity of the acceleration using a [3×3] optical coupler.