| 摘要 |
PURPOSE:To detect an accurate displaced position of an electrified body in an electrostatic electroscope optically, by measuring the opening of the electrified body in the electroscope by means of the variation of bright and dark lines on a diffraction pattern. CONSTITUTION:When an ionization chamber 1 is irradiated by X-rays, pairs of ions generated in air in the ionization chamber 1 are collected in the electric field between an anode 8 and a cathode 9 to take away electric charge from an electroscope 2 and to close an electrified body. And when a laser beam 21 is irradiated on a diffraction grating attached to the electrified body to observe a diffracted beam 22, a diffraction pattern of the diffracted beam 22 can be observed depending upon the variation of the opened angle of the electrified body. By counting variations of bright and dark lines in the diffraction pattern with a photodetector 3, a closed angle of the electrified body, that is, an amount of ionization can be obtained to calculate the X-ray dose with a dose arithmetic circuit 7. Thereby the opening of the electrified body in the electrostatic electroscope can be measured by means of the variation of bright and dark lines in the diffraction pattern to obtain the displaced amount of the electrified body optically.
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