| 摘要 |
PROBLEM TO BE SOLVED: To provide a foreign material detector which can be downsized and has high precision in detection. SOLUTION: This minute foreign material detector S comprises a floodlight unit 30 which can launch laser beam, a photosensor camera 40 having a receiver 41 with an imaging device arranged in procession on its light-receiving face 41A, and a controller 50. The controller 50 comprises CPU 51, control circuit 53, frame memory 55, RAM 56, ROM 57, and others. The CPU 51 receives image data of the photosensor camera 40 to acquire power spectrum distribution through Fast Fourier Transform of the above image data. By repeating this processing, the time shift of the power spectrum distribution is acquired. Since diffraction stripe appears in image data if any foreign material exists on a glass substrate, variation will be found in power spectrum distribution. Thus the foreign material can be detected from the time shift of the power spectrum distribution. COPYRIGHT: (C)2007,JPO&INPIT |
