Online control for Cs-O layer of NEA photocathode
摘要
As compared with III generation intensifiers, IV generations have bigger sensitivity and much broader spectral response for low light level imaging detectors. IV generation intensifier properties are improved for NEA photo-cathode sensitivity and spectral response. In this paper, a new method is introduced to increase NEA photo-cathode sensitivity and expand infrared response. In the method, spectral response of GaAs:Cs-O NEA photo-cathode is controlled with automatic survey instrument of dynamic spectral response on photo-electronic materials. During processing NEA photo-cathode, it is observed that sensitivity rises slowly when photo-cathode is illuminated with incident ambient radiation, and infrared sensitivity begins reduction when photo-cathode is measured with automatic survey instrument. The reduction of infrared sensitivity has influenced on spectral matching factor of photo-cathode-object combination and detecting distance and has resulted in the practical use of low light level night vision instrument. During processing NEA photo-cathode with Cs-O layer, we can keep watching spectral response change with automatic survey instrument: when sensitivity rises slowly as photo-cathode is illuminated with incident ambient radiation and infrared sensitivity reaches a highest peak value, we can achieve optimum GaAs:Cs-O photo-cathode for low light level imaging detectors. We studied the thickness of a layer GaAs:Cs-O photo-cathode with take off X-Ray photo-electron spectroscopy, it is clear that the thickness of Cs-O layer is about 0.7~1.0 nm.