| 摘要 |
PURPOSE:To make the head small in size and low in cost and to facilitate the assembling thereof. CONSTITUTION:Laser beam exciting from a semiconductor laser 11 and reflected on a medium 1 is made incident to a hologram element 3 and light diffracted thereon is entered into two bi-secting light detectors 9 and 10. Then, one of diffracted light becomes circular polarization by a Q-wave-length 4. Only the component of one polarization direction passes through an analizer 5, and entered into a light detector 9 to detect a light quantity distribution. The other diffracted light becomes circular polarization by a Q-wave-length plate 7. Only the component of a polarization direction which is orthogonal to the polarization direction passes through an analizer 8, and enteres into a photodetector 10 to detect a light quantity distribution. At this time, since laser light 12 is straight polarized light, it can be considered to be synthesized right-handed circular polarization and left-handed circular polarized light and the components are respectively detected by the photodetectors 9 and 10. |
