Measurement of distance to diffuse surfaces using non-scanning coherence radar

An interferometer without moving parts is proposed for measurement of distances to, or distance differences between, diffuse surfaces. The interferometer, which is a variation of the non-scanning white-light interferometer, utilizes the limited coherence of the light source. The light is divided by a beamsplitter and reflected from two surfaces, one reference and one object surface. After recombination it is spatially filtered. A distance difference causes a delay between the reflections. The delay can be measured with the non-scanning white-light interferometer, by finding the positions of the correlation peaks. Since there are no moving parts, the interferometer can be used to measure rapidly moving objects.