| 摘要 |
PURPOSE:To ensure the automatic switching for the size of the scanning light spot in a simple method, by inserting the round slit into the optical path which illuminates the rectangular slit. CONSTITUTION:Round slit 9 is inserted into the optical path between lens 5 and rectangular slit 6 of rotary optical system 1. As a result, the laser beam is kicked by slit 9 and thus illuminates slit 6 in the same size as slit 9. Accordingly, the scanning light spot formed on the film surface by image forming lens 8 is reduced more for its width in the secondary scanning direction than the case of only slit 6. The diameter of slit 9 is set to the value that is decided by the density of the scanning line, and thus the scanning light spot to secure the optimum receiving picture can be set by selecting a proper distance between slits 6 and 9. In this way, system 1 is turned round the center axis of system 1 to perform the main scanning and with selection of the light spot. While the secondary scanning is carried out by shifting hollow cylinder 2 toward the axis. Thus the sharp recording is ensured. |
