| 摘要 |
PURPOSE:To enable the securing of a broad dynamic range with a single unit, by changing a voltage to be applied to a photoelectric multiplier tube according to a light detection output. CONSTITUTION:A light detection current Ip output from a photoelectric multiplier tube 1 according to the quantity of light l to be detected, converted into a voltage E0 with a current-voltage converter 3 of a detection circuit 2 and a high voltage is applied via a switch SW from a power source 5. Consequently, the voltage 5 supplies the voltage E0 by reducing the absolute value of a small driving voltage (-VH) all for the larger voltage E0. Therefore, the sensitivity of the multiplier tube 1 is automatically heightened for less quantity of light and it automatically lowered for a larger quantity of light, thereby compressing variation of the detection voltage E0. This can secure a broad dynamic range with a single photodetector.
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