APPARATUS FOR INSPECTING SURFACE OF TRANSPARENT SPECIMEN PLATE

PURPOSE:To enhance an S/N by perfectly eliminating beam reflected and scattered to a transparent specimen plate, by providing a beam trap means in the vicinity of the transparent specimen plate in the side of a laser beam transmitting direction. CONSTITUTION:A light trap means 9 is provided in the vicinity of a transparent specimen plate 8 in the side of a laser beam transmitting side. By this constitution, the laser beam transmitted through the transparent specimen plate 8 is received by the beam trap means 9 and can be attenuated by guiding said beam to the direction different from the position where the transparent specimen plate 8 has been held while said beam is reflected many times. Therefore, the beam reflected and scattered to the transparent specimen plate 8 is perfectly eliminated and the beam scattered from a part other than the surface of said specimen plate 1 is prevented from being incident to a photoelectric converter 6 receiving scattering beam from the surface of the transparent specimen plate as stray beam and a S/N ratio is enhanced.