| 摘要 |
PROBLEM TO BE SOLVED: To converge two kinds of light different by wavelengths, which correspond to optical recording mediums different by recording capacities respectively, on the same position on a light detection means. SOLUTION: An optical pickup device 31 includes an optical recording medium 33, a light source 32 which emits two kinds of light different by wavelengths, a first converging means 34 which is arranged between the light source 32 and the optical recording medium 33 and converges the light emitted from the light source 32 on the optical recording medium 33, a light detection means 35 which detects reflected light from the optical recording medium 33, and a second converging means 36 which is arranged between the light detection means 35 and the optical recording medium 33 and converges reflected light on the light detection means 35. The second converging means 36 includes a diffraction grating 37, and the diffraction grating 37 makes one light incident on the center of the light detection means 35 without correcting the optical path of one light and corrects the optical path of the other light, which is different from that of one light, to make the other light incident on the center of the light detection means 35. Thus the light detection means 35 can obtain a detection signal of high precision for either light. |
