| 摘要 |
PURPOSE:To form a fine spot without the generation of unevenness over the whole range of a scanning direction by compensating the defocusing of a condensed beam which may be generated at the time of constant speed plane scanning by a constant speed reflector through the 1st condenser. CONSTITUTION:A laser beam radiated from a laser light source 1 is modulated by a modulator 2, expanded to parallel light by a beam expander 3, reflected by a reflector 9, and then turned to a condensed beam by an autofocusing condenser 10 and a condenser 11. The condensed beam is scanned by a rotating polyhedral reflecting mirror 5 and then scanned on a recording part at a constant speed by a constant speed reflector 12 and reflectors 13, 14. Since the autofocusing condenser 10 can moved in the optical axis direction, the arc-like locus of the condensed spot is converted into a linear locus by the condenser 10, so that the defocusing of the condensed spot beam is not generated. |
