| 摘要 |
PURPOSE:To realize an effective separation of plural pieces of luminous flux through a small-sized device, by making at least two pieces of luminous flux forming a slight amount of angle to each other incident to the boundary surface of media having different refractive indeces with angles larger and smaller than the critical angle. CONSTITUTION:A main beam A and secondary beam B of a laser beam source 1 are condensed on a recording surface 7 of a disk 6 via a collimator lens 2, a polarizing prism 3, a 1/4 wavelength plate 4 and an objective lens 5 respectively. The reflected light goes backward and is made incident to a boundary surface 9-1 of a detecting prism 8 after passing through the prism 3. The main beam A is made incident to the surface 9-1 with an ange larger than the critical angle; while the secondary beam B is made incident with an angle smaller than the critical angle respectively. The beam B transmits through the surface 9-1 to be detected by a photodetector 11. The beam A is reflected on the surface 9-1 and then made incident again to a boundary surface 9-2 with an angle larger than the critical angle to be detected by a photodetector 10 after repeating the reflection. In such way, plural pieces of luminous flux can be effectively separated through a small-sized device. |
