Coherence radar
The coherence radar is a white light interferometer with which the shape of smooth and rough surfaces can be measured.
While white light interferometry on smooth surfaces has been known for a long time, it was only possible to measure rough surfaces with coherence radar. Interference creates speckle patterns on rough surfaces . In contrast to laser triangulation , in which the speckle interferes with the measurement result, here they are the carriers of the (depth) information: The distance of each small surface piece corresponds to the distance at which the speckle has the maximum interference contrast from this surface piece .
The result of the coherence radar is the topography of the surface . In the case of translucent layers, it is in principle also possible to get information from deeper layers with the coherence radar, but there are special tomography methods that are more suitable for this task, such as optical coherence tomography .
Web links
- Light source for the coherence radar
- Device description coherence radar ( Memento from August 4, 2007 in the Internet Archive )
- Original publication on the coherence radar scientific article in English (from Applied Optics, Vol. 31, No. 7, p. 919-925, 1992)