| 摘要 |
PROBLEM TO BE SOLVED: To receive diffracted lights with a photodetector having a narrow width by bringing optical paths of diffracted lights to be generated from a holographic pattern near a light source. SOLUTION: Diffraction gratings are formed on the first surface 60b of an optical element receiving the beam reflected on an optical storage medium. The first surface 60b and the second surface 60a of the optical element have a nonparallel relation. After diffracted lights 73, 74 generated in diffraction gratings are refracted at the time of being transmitted through the second surface 60a and the paths of the lights are deflected to the sides near to the light source, the lights are received with a photodetector 50. |
