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 i s based on optical fibers or fiber coupled components only and therefo re is compact, portable, easy to align, and enables measurements in ha rd to reach locations. It also does not require a source of long coher ence length (only a few wavelengths, regardless of the optical path di fference or the surface displacement). This interferometer removes the directional ambiguity of the acceleration using a [3x3] optical coupl er. (C) 1996 American Institute of Physics.