LIGHT BEAM COMPOSITING METHOD, LENS FOR COMPOSITED LIGHT BEAM, AND MULTI-BEAM LIGHT SOURCE UNIT

摘要

PROBLEM TO BE SOLVED: To composit light beams having different wavelengths into a light beam group suitable for a multi-beam scan and to image the respective light beams at a deflecting and reflecting surface position of an optical deflector as a linear image which is long in the horizontal scanning direction. SOLUTION: The light beams which have the different wavelengths are composited into the light beam group for multi-beam scanning by using dichroic mirrors 7 and 8 and the composite light beam group is imaged at the position of the deflecting and reflecting surface 10A of the optical deflector 10 as the linear image which is long in the horizontal scanning direction by a common anamorphic lens 11. The positions of incidence of the respective light beams on the anamorphic lens 11 are shifted from one another in the horizontal scanning direction and set and the arrangement style and/or shape of the anamorphic lens is so set that the respective light beams form the line image at the position of the deflecting and reflecting surface 10A irrelevantly to the wavelengths.