| 摘要 |
PURPOSE:To improve the photodetection efficiency of reflected light or the like from a storage medium by allowing a light waveguide element arranged between a photodetector and the recording medium to make a read light incident on the recording medium to bring the photodetector sufficiently close to the recording medium. CONSTITUTION:The photodetector 20 is provided in face with a rotary drum 10 storing a storage fluorescent sheet 13 on which radiation picture information is stored and recorded and the light waveguide element 25 is fixed to a photodetection face 20a of the detector 20. The element 25 is arranged in a way that a light incident grating coupler 28 is unlocked from the detector 20, receives stimulated light 24 and a light radiation light condensing grating coupler 29 is opposed to the circumferential surface of the drum 10. Then the element 25 is made very thin as 1mm or below including the thickness of a disc 26 and the distance between the photodetection face 20a of the detector 20 and the sheet 13 is set sufficiently smaller even taking the optical path length for focusing the light 24 into consideration. Thus, the detector 20 is brought very close to the sheet 13 and the photodetection efficiency of the reflected light or the like from the sheet 13 is improved.
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