Patent ID: 8253994

Claim:
An optical scanner comprising: an optical scanning means for reflecting on a reflecting surface a light flux emitted from a light source, while at the same time, scanning said light flux in a linear direction as a main scanning direction toward a prescribed surface to be scanned; and an image forming means disposed in between the optical scanning means and the surface to be scanned for forming an image on the surface to be scanned with a scanning light scanned by the optical scanning means, while at the same time, keeping a scanning speed of the scanning light nearly-constant on the surface to be scanned; and wherein, the image forming means comprises: a first lens having a positive power in the main scanning direction and a negative power in the sub-scanning direction, that is orthogonal to the main scanning direction; and a second lens disposed in a closer position to the surface to be scanned than the first lens, having a negative power in the main scanning direction and a positive power in the sub-scanning direction; and wherein the optical scanner fulfills a condition: −1.2≦φ2 m/φtm≦−0.48 when a power of the image forming means, that combines the first lens and the second lens, in the main scanning direction is φtm, and a power of the second lens in the main scanning direction is φ2m.