| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical scanner with an excellent beam spot shape, stable beam spot size and optical power and high availability of optical power. SOLUTION: This optical scanner is constituted so that a real image 63 of an aperture 61 is arranged so as to be placed on a deflector side of a surface to be scanned 17, and the real image 53 of a light source 1 is arranged so as to be placed on the side opposite to the deflector of the surface to be scanned 17 in the sub-scanning direction, and the surface to be scanned 17 is arranged on a nearly beam waist position in the sub-scanning direction, and the aperture 61 is set so as to shield the part of the outside in the sub-scanning direction from a position of 25% or below for a central intensity of a light beam, and the fluctuation in the beam spot size due to the defocus of the surface to be scanned 17 is minimized, and the part that the beam spot size is minimum is used, and further, the availability of the optical power is enhanced. |
