| 摘要 |
PURPOSE:To obtain an accurate picture signal fitting an actual picture by decreasing the amount of accelerated phosphorescence afterglow by scanning the surface of an X-ray picture conversion panel with excitation light while sequentially repeating its irradiation and stopping. CONSTITUTION:A signal applied with photoelectric conversion by a photodetector 401 is converted to a voltage by a current-voltage converter 402, and inputted to a sample holding circuit 404 via an amplifier 403. In the mean time, a synchronizing signal generating device 407 synchronizes the timing of the modulation (irradiation) of a laser beam which is the excitation light with the timing of the sample-holding of the circuit 404. Accordingly, the circuit 404 detects an output signal from the amplifier 403 in synchronization with the irradiation of the laser beam, and holds it in order to interpolate a signal in the state of stopping the laser beam. As a result, since the signals corresponding to the amount of afterglow are decreased by the modulation of the laser beam, a logarithmic converter 408 supplies an accurate picture signal well corresponding to the actual picture.
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