| 摘要 |
PURPOSE:To improve inspection ability and inspection efficiency by deciding on the photodetection level of reflected light from a body to be inspected and the extent and direction of a displacement in photodetection position, and discriminating whether a surface defect of the body to be inspected is present or not and its kind on the basis of said decision results. CONSTITUTION:A video disk 1 is set on an inspection table 3 and rotated at a constant speed, and its surface is irradiated with laser light 4a from a laser device 2. Its reflected light 4b is photodetected by a position detector 6 continuously, and amplified by an amplifying circuit 7 and processed by the addition and subtraction of an adding circuit 8 and a subtracting circuit 9 respectively to detect the photodetection level and displacement in photodetection position. Then, a pohotodetection level decision circuit 10 decides on the photodetection level obtained by the adding circuit 8. A displacement extent decision circuit 20, on the other hand, decides on the signal which is obtained by the subtracting circuit 9 and shows the displacement in photodetection position. Further, a displacement direction decision circuit 30 decides on the displacement in photodetection position. A decoder 40 discriminate on whether a defect is present or not and its kind on the basis of the respective decision results. |
