Patent ID: 6847028
Filing Date: 2005-01-25
Classification: H01J

Abstract:
1. A photomultiplier tube comprising: a tube-shaped vacuum vessel extending along a tube axis, the tube-shaped vacuum vessel having a first end and a second end in relation to the tube axis; a photocathode positioned on the first end of the tube-shaped vacuum vessel, for converting incident light to electrons; a plurality of dynodes arranged in n stages each having a secondary electron emitting surface formed on an inner wall thereof, for multiplying electrons sequentially; and an anode for receiving the electrons multiplied by the plurality of dynodes, the anode including a mesh electrode and an anode frame for retaining the mesh electrode, wherein the anode frame is substantially rectangular in shape wherein an electron converging part at which electrons multiplied by the plurality of dynodes converge is formed near a center part on one long side of the anode frame, and wherein inner surface of the anode frame has a such a shape that is nearest to the one long side of the anode frame at a center point of the one long side and that is gradually farther from the one long side with increased distance from the center point, so that the anode frame grows thicker on the one long side with increased distance from the center point.