Automatic photoelectric detection equipment - monitors optical features, such as surface marks or other optical inhomogeneities

摘要

A light beam with a rotating polarisation plane is generated; with a reference signal whose phase is correlated with the rotating polarisation plane azimuth phase. The light beam is split in two components with complementary polarisation states; the components are directed onto the object; After the beam components have been affected by the objects, and depending on the number of coordinate directions, they are converted into electric test signals with or without taking into consideration their polarisation, the test signals are combined with the reference signal in order to produce an output signal whose polarity is determined by the phase difference between the signals to be combined, and the output signal polarity and amplitude are evaluated.