| 摘要 |
PURPOSE:To enable advanced reading of a prescribed part of a face to be scanned by moving a 1st grid part at the main reading and a 2nd grid at the advanced read relatively to an optical beam so as to arrange them on the optical path of the branched light beam, respectively. CONSTITUTION:A synchronizing laser beam 2B reflected in a half mirror 6 is made incident on a grid 14 provided at a position conjugated with a storage fluorescent sheet 8 with respect to the mirror 6 while being prolonged in the main scanning direction. The grid 14 consists of a grid 14A for the main read and the grid 14B for the advanced read. A beam adjusting means 20 capable of going out and coming in with respect to an optical path of the laser beam 2 comprising an ND filter 17, a prism 18 and a concaved lens 18 is provided between a beam expander 3 and a rotary polygon mirror 4 and the means 20 is saved at the outside of the optical path at the main read, while being inserted in the optical path at the advanced read to adjust the laser beam. The luminous quantity change in the laser beam 2B is detected by a photodetector 16. Thus, the prescribed part of a face to be scanned is read in advance.
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