| 摘要 |
PURPOSE:To cope with several kinds of machines whose scanning speeds are different by one scanning optical system by changing the light utilization efficiency of a light source, by providing a lens holder for supporting a compressor lens, so as to be freely attachable and detachable between a collimating lens and a deflection scanning means. CONSTITUTION:In a device for scanning successively a laser light onto a photosensitive body through an ftheta lens 15 by a deflection scanning means, a compressor lens group consisting of a convex lens 18 and a concave lens 19 is supported by a lens holder 17, and its lens holder 17 is provided so as to be freely attachable and detachable between a collimating lens 12 and the deflection scanning means. In such a way, in the case of a machine whose scanning speed is high, a suitable lens holder 17 is selected and attached, and in the case of a machine whose scanning speed is low, it lens holder 17 is removed, by which the light utilization efficiency of a light source can be changed.
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