| 摘要 |
PURPOSE:To enable to obtain a highly accurate detective value irrespective of a spot diameter by scattering a laser beam with a photo-scattering filter and taking it out as a photo-intensity signal with a photo-sensor or located on a photo-receiving surface. CONSTITUTION:A photo-filter 1, a photo-scattering filter 2 and a photo-sensor 4, etc. are installed. A laser beam 9 is introduced to the filter 2 via the filter 1, scattered as an arrow 9a and irradiated on a photo-receiving surface 3 while eliminating the high frequency range of the spatial frequency of a laser beam. Thus, removing an influence of the folded frequency enables to obtain the meaningful data when the recording is regenerated. I.E., by irradiating a scattered laser beam on the sensor 4 located on the photo-receiving surface 3, a photo- intensity signal of an irradiated beam is taken out by the sensor 4 and the signal is calculated with a Gaussian distribution characteristic by a computer 5. Thus, a center position of a laser beam irradiation spot can be obtained accurately. |
