| 摘要 |
A high-resolution light-beam scanning apparatus utilizing only mass-producible holograms instead of utilizing auxiliary optical systems such as optical lenses or a mirror having curvature, and capable of compensating for disadvantages including scanning beam thickening and variation, failure of a rotatable hologram to rotate at a constant velocity, displacement of a scanning beam position in the scanning direction and the cross scanning direction due to a mode hop of a wavelength of a semiconductor laser, and deviation of a base of rotatable hologram from a parallel state. These disadvantages are detrimental to efforts for increasing the resolution of a hologram scanner and lowering the cost thereof. The 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 surface.
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