| 摘要 |
<p>PURPOSE:To prevent the erroneous recognition of the size of a foreign material irrespective of the aging deterioration in sensitivity of a laser tube and a photo detector by forming a bypass for inputting a light directly to the photo detector without passing a laser light through reticles and judging the size of the material by the proportion of the scattering light of the material at that time. CONSTITUTION:The rotating angle of a vibration mirror 3 is widened so that a laser light is directed to an inlet 6 at a certain period. In case of regulating the sensitivity in a sample of known foreign material, not the absolute value of an electric signal obtained by the scattering light 7 but the ratio of an electric signal of scattering light 7 to the size of an electric signal of a photo detector 4 from the laser light obtained through a bypass 5 at a certain period is used as a criterion for judging the size of the material. The laser light is always received directly by the detector 4, and with the electric signal used as the reference the magnitude of the electric signal from the scattered light 7 is relatively judged.</p> |
