| 摘要 |
PURPOSE:To improve the detection precision of surface defects by reducing effectively the noise which is generated inevitably in case of defect detection. CONSTITUTION:The light which is irradiated from a light projector A and is reflected on a part to be detected of hot metallic materials S is condensed together with the spontaneous light of the part to be detected and is made incident on an image pickup device B. This incident light strikes a cold mirror 2 as a spectral filter and has visible rays reflected but has near infrared rays transmitted through, and thus, the incident light is separated into its spectral components. However, since near infrared rays are mixed in the reflected light, an infrared ray absorbing filter 3 is arranged before a linear array image sensor 4. Similarly, since near ultraviolet rays and read region rays are included in the light transmitted through the mirror 2, the light is filtered by an infrared transmission filter 5 to allow a linear array image sensor 6 to receive only the spontaneous light in the near infrared region. The reflected light and the spontaneous light from the part to be detected are converted photoelectrically by sensors 4 and 6 respectively and are sent to a signal processing circuit C as electric signals of two systems. |
