| 摘要 |
PURPOSE: To solve the shortage of information recording surfaces by installing first and second signal detectors and using each signal detector for detecting the information regenerative signals of the first and second recording surfaces of a hologram disk. CONSTITUTION: When a first light source 12A reproduces a signal on the first recording surface 33 of a hologram disk 30, a second light source 12B is tuned off. Light beams 13A from the light source 12A are input to a first diffraction device 50 at that time while being divided into zero and ±first-order three beams 15A. The focus of beams is adjusted onto the first recording surface 33 of the hologram disk 30 by an objective 56, and beams 17A reflected by the recording surface 33 are projected to a second diffraction element 60. A pair of diffracted light beams 18, 19 are forwarded to a first detector 24. On the other hand, a second detector 25 reads an information regenerative signal from the second recording surface 35 of the disk 30 with the light source 12B turned on, for reproducing information from the second recording surface 35. |
