| 摘要 |
PURPOSE:To facilitate a fine adjustment correction of an illuminance spot and to reduce the manufacture cost of the device by composing a light shield plate of a thin plate type elastic body and installing it at a specific angle to an optical axis, and curving and deforming the light shield plate near its end part. CONSTITUTION:A holding plate 18 is vertically movable along a stay 17, so variance in the absolute level of an output due to variance in the F number of a lens 6, sensitivity of a photodetecting element CCD7, etc., is adjustable by varying the light shield quantity of luminous flux. Further, screws 22a and 22b are shifted in position in screw holes 23a and 23b to slant the holding plate 18 and light shield plate 19 to the horizontal direction, thereby varying the inclination of the light shield quantity on the whole. Further, the curvature of the light shield plate 19 is varied by adjusting finely left and right adjusting screws 21a and 21b to obtain a left-right uniform light quantity distribution. Consequently, the fine adjustment correction of the illuminance spot is facilitated and the device cost is reduced.
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