| 摘要 |
A technique is provided which enables proper correction of optical characteristics in accordance with change in ambient temperature. An optical beam scanning device capable of causing a luminous flux from a light source to scan a photoconductive surface of each of plural photoconductors in a main scanning direction, includes: a polygon mirror 80 which reflects and deflects an incident luminous flux by plural reflection surfaces arrayed in a direction of rotation, and thereby causes the incident luminous flux to scan in the main scanning direction; and a post-deflection optical system A which includes plural optical devices and which guides the luminous flux reflected and deflected by each of the plural reflection surfaces in the polygon mirror 80, to a photoconductive surface of a photoconductor to which the luminous flux should be guided. Of the plural optical devices forming the post-deflection optical system A, in at least one optical device on which a principal ray of the luminous flux which should be guided to each of the plural photoconductors becomes incident at different incident positions from each other in a sub scanning direction orthogonal to the main scanning direction, a diffraction grating is formed at least on one of an incident surface and an exit surface of the luminous flux in the optical device.
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