| 摘要 |
PURPOSE: To improve signal throughput by obtaining high reflectances concerning TM-polarized light and TE-polarized light by using binary reflection element. CONSTITUTION: A laser light source 12 emits a linearly polarized TM mode light beam. A binary reflection element 16 is arranged at an angle of 45 degrees to the directions of the light source 12 and a pickup lens 18. TM-polarized light made incident on the element 16 is reflected onto a 1/4 wavelength plate 28. The TM-polarized light is converted into left circularly polarized light, and is focused on an optical storing medium 24 by the lens 18. A radiation density reflected from the medium 24 is determined according to contents of the information coded in the medium 24. Further, right circularly polarized light is linearly TE-polarized by the wavelength plate 28, and is reflected by the element 16 to a quad detector 22. On the quad detector 22, the radiated light is decoded, and a focus is determined and a proper focus adjustment signal is transmitted to the lens 18. |
