| 摘要 |
<P>PROBLEM TO BE SOLVED: To attain highly accurate and stable tracking operation. <P>SOLUTION: An optical apparatus comprises a light source 23 for emitting light, a diffraction grating 311 for dividing outgoing light emitted from the light source 23 into a main beam and two sub-beams, a hologram 312 for diffracting the return lights of the main beam and the sub-beams, and a light receiving part 25 for receiving the diffracted beams diffracted by the hologram 312; where the hologram 312 diffracts the return light of each sub-beam and divides the diffracted beam into two diffracted beams and the sizes and positions of light receiving areas of photodetectors 252b, 252c for receiving the diffracted beams of the return lights of the sub-beams in the light receiving part 25 are set so as to include a beam spot separated from the diffracted beam of the return light of the main beam out of respective beam spots based on the two diffracted beams. <P>COPYRIGHT: (C)2007,JPO&INPIT |
