Light beam scanning apparatus

摘要

A light-beam scanning apparatus includes at least two holograms with an optical path length difference DELTA PHI along a scanning beam light flux. The path length is measured from a light source to a scanning surface in the first hologram, and is represented by DELTA PHI <C( lambda 2/D lambda ) where C is a constant less than 0.5. The path length is related per the above equation to a wavelength, lambda , at the center of the light source, and a wavelength displacement DELTA lambda measured from the wavelength lambda at the center of the light source.