| 摘要 |
<P>PROBLEM TO BE SOLVED: To remove stray light or inter-layer cross talk smoothly with an inexpensive and simple configuration while keeping the availabilty of reflected light rays highly. <P>SOLUTION: Phtodetectors 112a, 112b, 112c are arranged at a position away from a condenser lens 110 than a converged position Fp of reproduced light rays Ln, and a hologram element 111 is arranged at a position closer to the condenser lens 110 than a converged position Fp of the reproduced light rays Ln. The hologram 111 divides the upper half part of the reproduced light rays Ln and guides the divided light rays to the phtodetector 112b. The photodetector 111a receives the lower half part of the reproduced light rays Ln. When the hologram 111 is removed, the upper half part of the reproduced light rays Ln is made incident on the photodetector 111c. Signals output from the photodetectors 112a, 112b, 112c are defined as Sa, Sb, Sc, respectively, then a reproduced signal S is obtained by operation of S=Sa+Sb+Sc. Thus, the influence of stray light to the reproduced signal S is removed completely. <P>COPYRIGHT: (C)2010,JPO&INPIT |
