| 摘要 |
PURPOSE:To prevent damage of a photomultiplier tube by providing a dynode feedback circuit to the preceding stage of a dark current correcting circuit and controlling a multiplication factor of the photomultiplier tube according to a signal quantity before correction. CONSTITUTION:Outputs of holding circuits 10, 11 are indicated respectively by the sum of a reference light signal or a sample light signal and a dark current signal, and are denoted as R+D and S+D. The dark current components are deducted from these both signals by dark current deducting circuits 19, 20, a ratio S/R of the sample light signal to the reference light signal is calculated by a dividing circuit 21 and displayed on a displaying device 15 through a signal processing circuit 14. On the other hand, an output of the circuit 10 is a value before deducting the dark current D, and is inputted into a comparator 12 and controlled so that it becomes a fixed value by a dynode feedback. |
