| 摘要 |
PURPOSE:To reduce size and weight, by focusing the luminous flux emitted from a light source onto an object to be irradiated, focusing again a part of the reflected luminous flux thereof, conducting the same to an optical transmission body, and detecting the change in the quantity of the reflected luminous flux transmitted by the optical transmission body. CONSTITUTION:An optical fiber 5 is an optical fiber for retaining the plane of polarization and transmits the linearly reflected light which is made incident thereto from one end to the other end without changing the polarization state. The luminous flux of the linearly polarized light emitted from the other end of the fiber 5 transmits a polarized beam splitter 7 and transmits a 1/4 plate 8, by which the light is circularly polarized. Said light is condensed by a condenser lens 11 and the condensed light is condensed through a substrate 14 on an information carrier surface 15, by which the light is reflected. The luminous flux modulated in such a way is again transmitted through the plate 8 after the transmission through the lens 11 and is made into the linearly polarized light having the plane of oscillation in the direction intersecting orthogonally with the direction of the incident light. Such light is reflected by the splitter 7. The reflected luminous flux is bisected by a beam splitter 12 and is made incident to single mode optical fibers 29, 30. |
