| 摘要 |
PURPOSE:To accurately decide a surface defect at a high speed by comparing light intensity signals of scattered light detected by a relative large photodetector and a small photodetector as to the regularly reflected light of beam light, and deciding the defect of a body to be inspected. CONSTITUTION:The beam light L from a light source 20 is projected vertically on the surface of the body 2 to be inspected through an objective 21. Light receiving elements 24 and 25 are installed at the angle of theta1 and theta2 (theta1>theta2) to the regularly reflected light R0 of the beam light via condenser lenses 22 and 23 so as to capture the reflected light of the light L. Those lenses 22 and 23 converge scattered light beams R1 and R2 on the surface of the body 2 to be inspected to form images on the elements 24 and 25. Those elements 24 and 25 convert their photodetected light beams photoelectrically and send electric signals V1 and V2 to a trailing arithmetic circuit 26. Then when the voltage V2 exceeds a threshold value VTH2, the presence of a projection surface defect is recognized. Here, a border line shown by V2=bV1<c>+d [where (b) and (c) are constants while b>0 and c>0 and (d) is a constant] where the signal V2 increases monotonously with the signal V1, and the signals V1 and V2 are compared to accurately obtain the defect. |
