Raster scanner, mirror supporting structure of the same and method for adjusting mirror angle using the structure

摘要

A raster scanner characterized in that at least one reflecting mirror is supported by a movable supporting mechanism in a manner capable of moving along an incident optical axis while being kept in a certain angle attitude or that an optical sub-frame provided with a beam generating means, a beam deflecting means and an imaging lens is supported by a movable supporting mechanism in a manner capable of moving along an output optical axis while being kept in a certain angle attitude to be able to avoid assuredly an occurrence of unbalance in image widths in the main scan direction at both ends of the image when length of optical path is adjusted. This invention also presupposes that the reflecting mirror is a cylindrical mirror. Angle adjusting performance of the cylindrical mirror is kept in good condition by rotating one end portion of the cylindrical mirror following to a rotation of the other end portion of the same centering on an axis parallel to a generating line of the cylindrical mirror. It also allows to correct inclination of the cylindrical mirror itself caused due to precision of the parts assuredly by minutely rotating one end portion of the cylindrical mirror while securing the other end portion of the same.