Patent ID: 6016192
Filing Date: 2000-01-18
Classification: G01J,H01J

Abstract:
An external calibration device for a photomultiplier tube having a light sensitive face comprising:a reference block having a chamber therein; an elongated light emitting diode having a dome shaped end extending into said chamber; a photo cell mounted in the chamber adjacent said dome, substantially perpendicular to the longitudinal axis of said diode;mounting means for coupling said block and said tube wherein the longitudinal axis of said diode is contained in a plane disposed at an acute angle to the light sensitive face whereby light from said diode simultaneously strikes said photo cell and the light sensitive face;circuit means comprising a closed loop feedback circuit coupled between said diode and photo cell and adapted to be coupled to said photomultiplier tube for calibrating the light intensity reading of said tube with the light intensity reading of said photo cell responsive to light from said diode.