| 摘要 |
An optical scanner for use with laser printers and the like. In the optical scanner, a semiconductor laser device is combined with an aperture and a collimator lens which is one single spherical planoconvex lens for collimating the emerging laser beam, the aperture and the collimator lens being arranged in that order on the side of the laser device from which the laser beam issues. The planar side of the collimator lens is directed towards the semiconductor laser device. The collimated laser beam is focused by a cylindrical lens to form a line image elongated in the main scanning direction. A polygonal mirror for deflecting the incident laser beam at a substantially uniform angular velocity in the main scanning direction is positioned in such a way that a reflecting surface of the mirror coincides with the position where the line image forms or with a nearby area. The beam reflected from the polygonal mirror is launched into an f theta lens, which converges it in such a way that a beam spot is scanned at a substantially uniform speed over the surface of a photoreceptor drum. For an installation-related reason, a reflector mirror is also provided between the f theta lens and the photoreceptor drum.
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