| 摘要 |
PURPOSE:To compensate the fall of a deflector and to eliminate an uneven pitch of a scanning line with a compact constitution, by forming a scanning image forming optical system which is provided between a deflector and a medium to be scanned with a single lens having a toric surface. CONSTITUTION:A scan optical system comprises the 1st image forming optical system 2 that forms the luminous flux given from a light source device 1, a deflector 3 and the 2nd image forming optical system 4 that forms a linear image into a spot on the medium 5. The system 4 includes a positive meniscus lens, i.e., a toric single lens comprising a surface having the negative refractive power at the deflector 3 side and a surface having the positive refractive power at the medium 5 side within a section vertical to the deflecting surface which is formed by the beam deflected by the deflector 3 and also includes the optical axis. As a result, both the image forming performance and the distortion properties of an image forming optical system can be compensated satisfactorily without using any means having a collimating function. |
