| 摘要 |
PROBLEM TO BE SOLVED: To achieve a scanning optical device capable of excellently correcting image surface curve and distortion aberration, and also reducing influences by variations in a spot diameter due to an image height, etc. SOLUTION: This device is constituted of a first optical element 2 converting a luminous flux emitted from a source of light means 1 into convergent light, a second optical element 4 forming an image of this luminous flux in a main scanning direction on a deflected surface of a deflection element 5 in a form of a longitudinal line, and a third optical element 9 forming an image of the luminous flux deflected by the deflection element 5 on the scanned surface in a form of a spot. In this case, this device is arranged so that the third optical element 9 is provided with a spherical lens 6 and a toric lens 7 located from the side of the deflection element 5; the surface of the spherical lens 6 is formed of a meniscus shape of a positive refracting power with the concave surface faced to the side of the deflection element 5; and the toric lens 7 is, in a main scanning section, formed of the meniscus shape of a positive refracting power in which the surfaces of both lenses 6, 7 are aspherical and the convex surface faces the side of the deflection element five in the neighborhood of the scanning center. |
