| 摘要 |
A diffusive optical element exploiting holography is designed in such a way that, the higher the intensity of incident light in a wavelength range, the lower the rate at which the intensity of diffused light in that wavelength range is reduced with increasing angle relative to the maximum intensity direction. Thus, the lower the intensity of incident light in a wavelength range, the narrower the range of angles at which light is diffused in that wavelength range. This makes it possible to use light diffused at angles within a predetermined range relative to the maximum intensity direction, and thereby enhance light use efficiency in a wavelength range in which light intensity is comparatively low. This diffusive optical element is employed in an illumination optical system, which is used to illuminate photographic film from which to read images.
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