Patent attributes
The present invention relates to a photodetector that has a structure capable of realizing a wide range gain adjustment for each of electron multiplier channels respectively assigned to a plurality of light incidence regions of a multi-anode multiplier. The photodetector comprises a multi-anode photomultiplier, and a bleeder circuit unit. The multi-anode multiplier has a dynode unit constituted by N (an integer or no less than 3) dynode plates, and n-th (an integer of no less then 2) dynode plate is constituted by a plurality of control plates respectively corresponding to the multiplier channels. The bleeder circuit unit has a primary section setting each potential of a first to (n−1)-th and (n+1)-th to N-th dynode plates, and a secondary section for individually setting a potential of each control plate at any potential within the range wider than a potential difference between the (n−1)-th and (n+1) dynode plates. By expanding the potential setting range for the control plates rather than the potential difference between the dynode plates adjacent to the n-th dynode plate, the gain of each electron multiplier channel can be controlled by two digits or more.
