Automatic sharp setting prior to the direction of a microscope in a surface inspection

摘要

PURPOSE:To automate observation and inspection of a plain and smooth sample plane with a surface observation device using a microscope by projecting illumination to the sample from the rear side thereof, picking up the image thereof by an image pickup means, subjecting the video signal thereof to a computation to evaluate the degree of focusing and determining the max. value. CONSTITUTION:The sample S is set on a sample stage 6 and the sample surface is segmented to small areas each sizes about 0.1mm square. A stage 6 is moved in X- and Y-directions with each segment by a control circuit 5 and an electronic shutter 14 is opened and 23 is closed by a change over switch 26 to set a focusing mode. The sample S is then illuminated from the rear. The video signal is taken by a television camera 3 into a focus detecting circuit 4 by which said signal is subjected to the computation to evaluate the degree of focusing. The stage 6 is then moved upward and downward by a pulse motor 8 and the signals are similarly subjected to the evaluation of the degree of focusing and are compared with the previous value. The illumination is changed over to reflection illumination after decision of focusing and the video signal is taken in by the camera 3. The circuit 5 makes decision of whether the video is defective or non-defective according to the presence or absence of the signal above the prescribed level and memorizes the result thereof. This operation is executed over the entire surface and the degree of focusing is evaluated by the positions and number of the defective sections. The focus detection of the plain and smooth sample is thus carried out.