| 摘要 |
PROBLEM TO BE SOLVED: To make variable the aspect ratio of the laser light beams emitted from a semiconductor laser and to irradiate an optical disk with laser light beams having sufficient power for a signal recording. SOLUTION: A semiconductor laser 1 generates laser light beams having a wavelength of 635 nm. A collimator lens 2 makes the laser light beams from the laser 1 parallel. An optical means 3 diffracts the light beams in the short axis direction of the laser light beams, that are made into parallel beams by the lens 2, to the outside the optical axis, makes the beams parallel, and emits the laser light beams having a prescribed aspect ratio. A half mirror 4 passes the laser light beams from the means 3 and reflects half of the reflected light beams at a signal recording surface 8a of an optical disk 8 toward the direction of a photodetector 7. An objective lens 5 converges the laser light beams and irradiates the surface 8a with them. A condenser lens 6 converges the laser light beams from the mirror 4. The photodetector 7 detects the laser light beams. The means 3 is preferably arranged in the region where the laser light beams are made parallel. |
