| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical scanner capable of reducing the uneven density of an image by using a post-deflection optical system including a plastic lens. SOLUTION: The optical scanner 1 is provided with a pre-deflection optical system 7 including a lens 9 for converting the light emitted from a laser diode 3 to collimated light or convergent light, a slit 10 for controlling the light quantity of the collimated light or the convergent light, and a lens 11 whose power at main scanning is different from that at sub-scanning, an optical scanning means 5 for scanning an object to be scanned with the collimated light or the convergent light, a pair of image forming optical systems 30 for transmitting the light scanned by the optical scanning means so as to form the image of the object to be scanned, and the slit of the predeflection optical system is provided with an aperture whose diameter is larger than the diameter of 13.5% of the light intensity of the light from the laser diode in at least one of the main and sub-scanning directions. Thus, flare is reduced and the uneven density of the exposed image is suppressed.
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