Patent ID: 6114621
Filing Date: 2000-09-05
Classification: H01J

Abstract:
A light detecting apparatus, comprising:a photocathode provided to receive light from a light emitting source originating externally to said light detecting apparatus and to emit photoelectrons in accordance with the light detected;an electron multiplying portion provided to multiply the photoelectrons from said photocathode;an anode provided to collect electrons from said electron multiplying portion;an envelope accommodating said photocathode, said electron multiplying portion and said anode; anda magnetically-shielding structure having:a housing made of a material magnetically shielding at least said photocathode while accommodating said envelope, said housing having a first opening for passing through the light to be detected toward said photocathode;a lens element transparent to the light to be detected, supported by said housing so as to close said first opening and to direct light to said photocathode; anda positioning structure provided so as to place said envelope at a predetermined position so as to define a distance between said photocathode and said lens element.