| 摘要 |
A coupling lens couples a light flux from a light source to form a parallel light flux, a convergent light flux or a divergent light flux. An optical deflector includes a deflective reflection surface which deflects the light flux from the coupling lens at a uniform angular velocity. A scanning image-formation optical system converges the deflected light flux received from the optical deflector on a surface to be scanned to form a beam spot. The device scans the surface to be scanned with the beam spot at a uniform velocity. A depth increasing component, increases the depth of focus determined by the entire optical system of the device, on the optical path between the light source and the deflective reflection surface.
|
