Optical scanner

摘要

An optical scanner that has a simple construction and which yet exhibits satisfactory imaging performance under varying temperature conditions. Of the two orthogonal scanning cross sections of scanning optics (i.e., the main and sub-scanning cross sections), the one that involves the greater movement of the image plane due to the temperature-dependent changes in optical characteristics (e.g. the variation in the operating wavelength of a light source, the index variation of a lens material and the thermal expansion of a lens itself) is adapted to be the same as the other cross section that involves the greater movement of the image plane due to the change in the distance from the light source to a collimator lens. If necessary, additional correction is effected in such a way that the scanning cross section that involves the greater overall movement of the image plane after correction for temperature changes is adapted to be different from the cross section that involves the greater amount of optical field curvature.