Abstract: This paper deals with a new active technology in optical shape measurement called inverse projected-fringe-technique. Using a programmable liquid crystal spatial light modulator (LCD- SLM) with digital pixel control a precise sinusoidal grating with arbitrary topology can be created and projected onto the object under test. In this case the grating can be adapted to the shape of the object not only to overcome possible problematic areas such as saturated regions and nonresolved fringes but to generate also a so called inverse pattern that causes straight and uniform fringes on the object if it is observed by the camera. This technique is of special advantage for shape control in the production line since only certain deviations from the uniform pattern have to be detected if the object has to be classified as good or bad. In that case a fast optical correlator can be used that needs almost the same simple filter mask for a broad variety of test objects. !10
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