| 摘要 |
PURPOSE:To obtain a scanning optical system which can reduce the influence caused by a temperature variation without increasing the number of component pieces of a scanning lens. CONSTITUTION:The system is constituted so that a semiconductor laser 1 and a collimating lens 10 are attached to a lens barrel 2 made of plastic, a first lens 21 made of plastic, having positive power in the main scanning direction and being anamorphic is provided in a cylindrical lens 20, a luminous flux is deflected by a deflector P provided in the vicinity of an image formed position of the luminous flux by the cylindrical lens 20, and the deflected luminous flux is subjected to image formation on the image face by an anamorphic scanning lens 30 made of plastic, and the system is set so that the linear expansion of the lens barrel 2 and the focal fluctuation of a first lens 21 are mutually canceled in the main scanning face, and linear expansion and a focal fluctuation of the scanning lens 30 negate each other in the sub-scanning face. |
