| 摘要 |
PROBLEM TO BE SOLVED: To realize a high C/N ratio in the optical head in which record and reproduction are conducted for disks, that are selectively arranged and have different thicknesses, without switching plural objective lenses. SOLUTION: Linearly polarized luminous fluxes from a light source are made incident on plural objective lenses 5 and 6 by an optical prism 4. The prism 4 has a luminous flux incident plane 4a on which the fluxes are made incident, a luminous flux branching plane 4b consisting of the polarizing film which branches the incident luminous fluxes, that are made incident on the plane 4a, into reflection and transmissive luminous fluxes at a prescribed ratio and a reflection surface 4f which emits the transmissive fluxes parallel to the reflection fluxes or emits the reflection fluxes parallel to the transmissive fluxes. The head has the prism 4, a luminous flux separating means which is located between the prism 4 and the light source and separates the luminous fluxes from the source and the returned light beams from an information recording medium by a polarizing film and a λ/4 plate 24 which is located between the prism 4 and the means above. |
