| 摘要 |
PURPOSE:To correct the deterioration of a spherical aberration in a collimater lens with a semiconductor laser as a light source by varying the special air interval of respective lens groups. CONSTITUTION:A correction ring 111 is rotated in either direction, a rectilinear ring 110 moves parallel to the condensing lens via a guide pin 109 and a long hole 105a at the optical axis. When the ring 110 moves, the guide pin 109 also moves along the long hole 105a and hence a rear lens-barrel 107 will also move in a direction parallel to the optical axis of the condensing lens. Accordingly, the interval of the lenses between the front groups L1, L2 and the rear group L3 will vary. Thus, the best spherical aberration matched to the wavelength of the used laser light can be obtained, and the irregularity of the protective transparent plate can be corrected. |
