Photomultiplier.

摘要

A photomultiplier has a focusing electrode plate (7) for supporting focusing electrodes, provided between a photocathode (3) and a dynode unit (60). Since the focusing electrode plate has holding springs (7a,7b) which are integrally formed with the focusing electrode plate, resistance-welding becomes unnecessary to prevent field discharge. A concave portion is formed in a main surface of the focusing electrode plate to arrange an insulating member (8a,8b) sandwiched between the focusing electrode plate and the photoelectron incidence side of the dynode unit and partially in contact with the concave portion. With this structure, discharge between the focusing electrode plate and the dynode unit can be prevented. <IMAGE>