| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical head device capable of accurately forming a diffraction grating for reflecting/diffracting a part of a laser beam in order to control the emitted light quantity of a laser beam source. SOLUTION: The hologram lens 3 of an optical head device 1 is provided with a first diffracting area 33, in which a first diffraction grating 331 for diffracting a returned light beam Lr from an optical recording medium 5 and introducing it to a signal photodetector 7 is formed, and a second diffracting area 34, in which a second diffraction grating 341 for reflecting/diffracting a part of a laser beam Lo from a semiconductor module 2 and converging it on a monitoring photodetector 8 is formed. The second diffraction grating 341 is constituted by forming a reflection part reflecting the laser beam Lo and a non-reflecting part transmitting the laser beam Lo through in a stripe-like shape. |
