| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical head capable of monitoring anterior light of a semiconductor laser, and also small in size and easy to assemble. SOLUTION: This is an optical head 10 equipped with a semiconductor laser 1, an objective lens 3, a hologram lens 2 having diffraction hologram 21 formed for diffracting reflected light from a recording medium 4 to be sent in a different direction from the semiconductor laser 1 and an error signal photodetector 5 to receive the diffracted light from the diffraction hologram 21, an anterior monitor photodetector 8 to receive a part of the anterior light of the semiconductor laser 1, and the error signal photodetector 5 and the anterior monitor photodetector 8 are provided on the same substrate 7, and a reflecting type hologram 22 for reflecting a part of the anterior light from the semiconductor laser 1 to be led to the anterior monitor photodetector 8 is directly provided on the hologram lens 2. |
