| 摘要 |
PURPOSE:To omit an optical member fitting board, to easily position a light emitting source on an optical system member and to reduce the size of the whole device by joining a concave lens with a beam splitter for guiding the reflected light beam obtained by reflecting a light beam radiated from the light emitting source by a recording medium into a photodetector and building the light emitting source in the recessed part of the joined part. CONSTITUTION:A triangular prism 1 is arranged on the inside of a movable part body 16 and an objective lens 2 opposed to the surface of a recoding medium disk 31 is arranged on the upper surface of the prism 1. Another triangular prism 3 is sticked to one inclined surface of the prism 1 to constitute the beam splitter and a sealing prism. On other hand, the concave lens 4 is sticked to the other side of the prism 1, the light emitting source 5 such as a laser is built in the recessed part 4a formed on the opposite side of the prism 1 to position the insertion depth of the light emitting source. Many grooves are formed on the adhering surface A between the prism 1 and the lens 4 so as to be provided with the function of a diffraction grating. A photodetecting element 8 as a photodetector is fixed on a space part 7 surrounded by both the rectangular prisms 1, 3. |
