| 摘要 |
PURPOSE:To facilitate the assembly and maintenance of a device by fixing in advance parts which require an installation with high accuracy especially, among each optical element parts of a deflection scanning optical system, to a prescribed position and constituting separately an integrated unit. CONSTITUTION:On a unit base 30, an ftheta lens 13 is provided on one end part in the center line X direction of a laser beam scanning angle, and in about the center part being near its other end, a polygon scanner 12 is installed. Also, a semiconductor laser 8 is provided by projecting it by a prescribed optical path length, at an angle of 45 deg. against the center line X of a beam scanning angle from the center of the scanner 12. Moreover, a cylindrical lens 11 onto a laser beam optical axis between the laser 8 and the scanner 12. These optical element parts are fixed and installed with high accuracy so as to become the prescribed relative distance and relative angle, respectively, and a deflection scanning optical system unit 20 is constituted. In such a way, at the time of assembling a device, each optical element parts can be assembled at a single stroke with prescribed position accuracy by only screwing 21 and fixing the unit 20 to a chassis.
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