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Y. Didosyan, H. Hauser, J. Nicolics:
"Magneto-optical Surface Evaluation";
Poster: 6th Int. Workshop on Electromagnetic Non-destructive Evaluation, Budapest, Hungary; 28.06.2000 - 30.06.2000; in: "Proceedings of the ENDE 2000", (2000), S. 55 - 56.

The progress of many optical methods of measurements of geometrical quantities is restricted because of a lack of appropriate light detection techniques. In many cases of non-destructive testing and evaluation it is necessary to measure the position of a light beam interacting with the surface to be measured (reflection, deflection, etc.). These measurements have to be done with a high spatial accuracy combined with high sampling rates. The existing photodetectors - charge-coupled devices (CCDs) and position sensitive detectors (PSDs) - however do not comply with these demands. Sampling rates of CCDs are typically as large as 1 ms and the pixel size is about 5 µm [1]. PSDs provide higher spatial resolution, but the reproducibility of the measurements is rather poor: e.g. for a 18 mm long receiving area the reproducibility equals 26 µm in the center of the photodetector and it is 4 times worse in the peripheral areas [2]. Moreover, the PSDs cannot measure positions of several light spots simultaneously.