| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical pickup device which selectively receives only returning light from a desired recording layer without using a pin hole. SOLUTION: In the optical pickup device in which light emitted from a light source 1 is condensed on a desired recording layer 6a of a multilayer recording medium 6 which has a plurality of recording layers in the direction of the thickness via an objective lens 5, returning light from the multilayer recording medium 6 is separated from the approaching route via the objective lens 5, returning light from the desired recording layer 6a among the returning light from the multilayer recording medium 6 is selectively received by a photodetector 10, a surface plasmon resonance film 9 which is composed of a metallic thin film is provided on the light-receiving face side of the photodetector 10, the returning light from the multilayer recording medium 6 is made incident so that the returning light from the desired recording layer 6a of the multilayer recording medium 6 which has a plurality of recording layers in the direction of the thickness is made incident on the surface plasmon resonance film 9 as a parallel light flux at a prescribed incident angle and a surface plasmon resonance occurs, thus only the returning light from the desired recording layer 6a is selectively received by the photodetector 10. |
