| 摘要 |
PROBLEM TO BE SOLVED: To make a pickup small in size and the degree of freedom of design large by differenciating the center of the surface on which a light beam from a light guide member is entered/emitted from the incident part of the beam. SOLUTION: A light beam emitted from a light source 1, reflected by a divergent angle converting hologram, a diffraction grating and a beam splitter film proceeds to an optical medium through a passing part 200 of the surface 5e of a member 5. The light beam reflected by the optical medium is passed again through the part 200, made incident on the member 5 and reaches a photodetector. In this case, a passing center of the part 200 of the surface 5e is made out of a center line 202 perpendicular to the transmitting direction 204 of the light from the light source 1 and a center line 203 along the direction 204 and provided close to the surface 5g of the member 5. Consequently, the inside of the member 5 is effectively utilized and the optical path long enough is obtained. Since the optical path between the light source 1 and the part 200 is made long enough, the light beam is efficiently guided around and the design of optical path is facilitated. |
