| 摘要 |
PURPOSE:To obtain a small-sized, inexpensive device with high performance by composing an optical image formation system of a single aspherical lens arranged between a laser diode and a rotary polygon mirror deflecting device and satisfying specific conditions. CONSTITUTION:This optical scanning device is equipped with the laser diode 2 which emits divergent luminous flux, the optical image formation system which converges the divergent luminous flux into a spot of desired size on an image plane, and the rotary polygon mirror deflecting device which deflects and scans the luminous flux. The optical image formation system consists of the single aspherical lens arranged between the laser diode and rotary polygon mirror deflecting device and meets requirements shown by expression, where (f) is the focal length of the lens, r1 the radius of curvature of the 1st surface of the lens at the peak, s1 the distance between the light source and the 1st main plane of the lens, s2 the distance between the image formation surface and the 2nd main plane of the lens, l1 the distance between the deflecting mirror surface of the rotary polygon mirror deflecting device and the image plane, and l2 the effective scanning width. Consequently, a uniform spot diameter with small aberrations is obtained only by the small-diameter single lens and the small-sized, inexpensive device with high performance is obtained. |
