| 摘要 |
PURPOSE:To synthesize plural laser beams to one beam without being influenced by a disturbance, by detecting optically a beam position shift, driving an actuator, and moving a lens or a laser. CONSTITUTION:Coupling lenses 13, 14 for collecting beams from semiconductor lasers 9, 10 are held by actuators 15, 16, respectively. When the laser 9 is shifted by a disturbance, two spots on a reference plate 21 move, a light quantity which is reflected and returned to a lens 23 is varied, an unbalance is generated in a light quantity of photodetectors 24, 24', and a difference is generated in an output current between opposed segments, therefore, this difference is detected and fed back to the actuator 15 as a spot shift detecting signal, and the center spot on the reference plate 21 is collected to the cross point. Accordingly, even if a position shift is generated in two condensing spots on a recording surface 12 by a disturbance, the lenses 13, 14 are moved on the surface vertical to the optical axis by an operation of the actuators 15, 16, and the two condensing spots can be adjusted so that there is no position shift. |
