| 摘要 |
PURPOSE:To detect precisely defects by receiving reflected and transmitted light beams from a subject to be inspected and separating the penetrating part and existing part of the subject to be inspected. CONSTITUTION:The laser beam of a laser spot beam scanning part 1 is reflected by a semi-transparent mirror 2, and scans the surface of the subject to be inspected 5. The laser beam 1b reflected on the surface passes through the mirror 2 and makes incident on a reflected light receiving part 3. On the other hand a laser beam 1c passing through the penetrating part of the subject to be inspected 5 makes incident on a transmitted light receiving part 4. The transmitted light beam 1c and the reflected light beam 1b are converted into electrical signals by photoelectrical converting parts 8 and 6. A synchronizing signal 7a takes synchronization in a separation processing part 9, and a reflected light signal 6a and a transmitted light signal 8a are added to output a signal 9a available from separating the penetrating part. Then the signals 7a, 8a and 9a are inputted to an edge removing part 10 to output a defect signal 10a. In a deciding circuit 11 the signal 10a is inputted and compared with a comparison reference signal, which detects a part becoming a low level as a defect. Accordingly even when the subject to be inspected has a penetrating part, defects can be detected. |
