| 摘要 |
PROBLEM TO BE SOLVED: To make magnification of a going path and magnification of a return path different from each other. SOLUTION: A laser coupler 1 is arranged so that laser beam exiting from the coupler 1 is reflected on a mirror 31 and subjected to S polarization. This S-polarized light is transmitted through a polarization hologram plate 32, subjected to circuit polarization in a λ/4 plate 33, reflected on the mirror 3, converged by an objective lens, and irradiates a recording medium 5. The light reflected on the recording medium 5 is made incident on the λ/4 plate 33 through the objective lens 4 and the mirror 3, subjected to P polarization, and made incident on the polarization hologram plate 32. The P-polarized light is processed by a convex lens and a concave lens in the polarization hologram plate 32, and reflected on the mirror 31, thereafter made incident on a photo-disk of the laser coupler 1. |
