| 摘要 |
PURPOSE:To contrive to secure the reliability of an inspection result by guiding scanning light to a photoelectric converter and comparing its output with a reference voltage signal, scanning the surface of a body to be inspected with a gain controlled and set according to the deviation, and thus obtaining a detection signal. CONSTITUTION:The reflected light for gain setting is made incident on the photoelectric converter 16 from a reflecting mirror 15 through the body 11 to be inspected and the output signal S3 of the photoelectric converter 16 is supplied to one input terminal of a comparison part 174 and compared with the reference voltage signal to set an amplification part 171 to desired gain according to the deviation. Thus, the gain is controlled and then light from a rotary mirror 13 moves to an original light scan on the body 11 to be inspected. Here, irregularly reflected light from the body 11 to be inspected is made incident on the photoelectric converter 16 and amplified with the bent gain which is affected by neither the intensity variation of the scanning light nor the sensitivity variation of the photoelectric converter 16 through an automatic gain control means 17, thereby outputting the detection signal. Consequently, a defect can securely be detected even when irregularly reflected light with small light intensity is used. |
