LASER SCANNING OPTICAL SYSTEM

摘要

PURPOSE:To reduce side lobe generated by diffraction and to improve the quality of an image by arranging a density filter maximizing transmissivity on an optical axis and continuously dropping the transmissivity in accordance with a distance separated from the optical axis in an optical path before a polarizing means. CONSTITUTION:The density filter 18 is arranged between a collimeter lens 4 and a rotary polygon mirror 12. The filter 18 has transmissivity characteristics minimizing the transmissivity on a center part corresponding to the optical axis and increasing the value in accordance with the distance from the center part to a peripheral part. When parallel light is shaped by the density filter, i.e. a kind of an aperture, having said transmissivity characteristics, the influence of diffraction can be reduced differently from shading due to an edge part of an ordinary aperture. Consequently, side robe in the distribution of beam intensity on recording paper can be reduced and the quality of picture can be improved.