| 摘要 |
PURPOSE:To reduce the size of a device and to provide the device with the function of a diffraction grating by joining a concave lens with the end surface of a beam splitter on the light emitting source side and forming grooves for applying the function of the diffraction grating on any one of joint surfaces between the beam splitter and the concave lens. CONSTITUTION:An objective lens 2 is arranged on the upper surface of a beam splitter consisting of two triangular prisms 1, 3 oppositely to the surface of a disk 31 to be a recording medium and the concave lens 4 is sticked to the end surface of the beam splitter on the light emitting source side, so that the optical of the light emitting system can be shortened and the size of the device can be reduced. Many grooves are formed on any one of joint surfaces between the prism 1 and the lens 4 to provide the device with the function of the diffraction grating. The positioning of the light emitting source 5 can be attained highly accurately on the basis of the recessed part 4a of the concave lens 4 and the forming position, shape, etc. of the stepped part 4b. |
