PURPOSE: To reduce cross talk and to improve spatial resolution by laminating transmission type dynodes and insulating plates alternately and making the dynodes and the insulating plates with different members.
CONSTITUTION: Mesh dynodes 1 of fine mesh structures held between two mask electrodes 2A,2B respectively and insulating plates 3 are laminated on each other alternately. Where, apertures of the electrodes 2A,2B and apertures of the plates 3 are opposed to one to one, and these apertures are positioned corresponding to respective anodes. That is, as mesh or lattice-shaped dynodes 1 are laminated on both sides of the plate 3, insulation between respective dynodes can be improved, and as secondary electrons are incident to the next step dynode 1 through the apertures of the plate 3, cross talk can be prevented perfectly. In addition, the dynodes 1 and the plates 3 are provided with different members, hence the relation between the pitch of the dynode 1 meshes and the pitch of apertures of the plate 3 can be specified arbitrally to improve spatial resolution.
HAKAMATA TOSHIICHI
MATSUI MASAO
NAKATANI TAKANORI
