| 摘要 |
PURPOSE:To reduce the beam intensity of stray light sufficiently by an optical component which is arranged on the incidence surface side of a photodetecting element and converges a laser beam in a subscanning direction by setting the upper limit of the laser beam transmissivity of the optical component to 65% and the lower limit to such a value that the photodetecting element can detect the laser beam. CONSTITUTION:The transmissivity of the correcting lens 73 of the plastic optical component 70 which is arranged on the incidence surface side of the photodetecting element 76 has its upper limit set to 65% and its lower limit to such a value that the pin diode 76 can detects the laser beam. The beam intensity is therefore reduced while the laser beam is transmitted through the correcting lens 73, and also reduced again while the laser beam which is reflected by a photodetection part 84 is transmitted through the corresponding lens 73. Consequently, the beam intensity can be reduced sufficiently and even if the beam returns to a polygon mirror 54 and is incident on a photosensitive body 62 as stray light, a false image is prevented from being formed.
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