| 摘要 |
PURPOSE:To obtain a light beam which has small transmission loss and a flat light quantity distribution in a scanning direction by providing aluminum as the lowermost layer of a light beam inflection mirror, a 1st dielectric layer with a small refractive index as its upper layer part, and a 2nd dielectric layer with a high refractive index as its upper layer part. CONSTITUTION:A laser beam 4 which is deflected through a newly provided cylindrical mirror 9 is incident on the inflection mirror 3 and the electric-field directional component E of the laser beam 4 is made nearly perpendicular to a deflection scanning surface. The inflection mirror 3 has an aluminum film 16 on a glass substrate 15, the SiO2 film 17 with the low refractive index on it, and the TiO2 film 18 with the high refractive index further on it. In this case, the respective films are so formed that nd is nearly lambda/4, where (n) and (d) are the refractive indexes of the SiO2 film and TiO2 film and lambda is the wavelength of the laser beam 4. Consequently, the loss of light laser transmission from a light source to a photosensitive body is reduced and the distribution of the quantity of light incident on the photosensitive body can be uniformed.
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