| 摘要 |
PURPOSE:To provide an optical head in which availability of light can be enhanced and focus error signal can be detected with high sensitivity and accuracy. CONSTITUTION:The optical head comprises a light source 16, means 14 for focusing the light from the light source 16 onto an optical recording medium 25, a hologram element 13 for diffracting light 27 returning from the optical recording medium 25, and optical detecting means 20, 21 for receiving light diffracted through the hologram element 13. The hologram element 13 comprises holograms 24a, 24b for pupil splitting a part of the optical recording medium 25 in parallel with the recording track direction, wherein the return light 27 subjected to primary diffraction through the holograms 24a, 24b is received by the optical detecting means 20, 21 thus detecting focus error signal of the focusing means 14 with respect to the optical recording medium 25. |
