| 摘要 |
PURPOSE:To obtain a compact light beam scanning device of simple constitution which is large in the scanning angle of a rotary polygon mirror and short in the optical path length by equipping the rotary polygon mirror with a light reflecting member and a lens member. CONSTITUTION:The rotary polygon mirror 1 consists of the light reflecting member 11 and an integrated lens member 12. The light reflecting member 11 uses aluminum or its alloy, etc., and the integrated lens member 12 uses glass, plastic, etc., for an optical lens which transmits a light beam in use well. It can, therefore, be considered that a light source is inside the focal length of an equivalent cylindrical lens and the light emitted from the light source inside the focal length of the cylindrical lens 12 is diverged by the cylindrical lens 12, so the scanning angle theta2 of the reflected light beam from the rotary polygon mirror 1 becomes larger than the scanning angle theta1 of a reflected light beam from a conventional rotary polygon mirror. Namely, when the rotary polygon mirror has the same number of surfaces, shorter optical path length is realized and the compact light beam scanning device is obtained. |
