LENS FOR OPTICAL SCANNING, SCANNING AND IMAGING LENS, AND OPTICAL SCANNER

摘要

PROBLEM TO BE SOLVED: To relax the tolerance of an assembly common difference by composing the scanning and imaging lens of the lens for optical scanning which increases in the absolute value of the radius of curvature in a deflection orthogonal plane toward a maximum value with the distance from the optical axis and then decreases after exceeding the maximum value position. SOLUTION: The lens which is closest to a scanned surface 8 between lenses 6 and 7 is the lens for optical scanning. The lens 7 for optical scanning is a 'meniscus lens having its concave surface on the side of an optical deflector', and the surface on the side of the optical deflector is a 'barrel-shaped concave toroidal surface having an axis of rotation parallel to a main scan corresponding direction'. Further, the surface on the side of the scanned surface monotonously and smoothly increases in the absolute value of the radius of curvature in the deflection orthogonal plane toward the maximum value with the distance from the optical axis in the main scan corresponding direction and then decreases with the same tendency after exceeding the maximum value position. Further, the line obtained by connecting the centers of curvature in the deflection orthogonal plane on the side of the scanned surface is curved in the deflection plane along the main scan corresponding direction.