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Title: Image intensifier gain uniformity improvements in sealed tubes by selective scrubbing

The gain uniformity of sealed microchannel plate image intensifiers (MCPIs) is improved by selectively scrubbing the high gain sections with a controlled bright light source. Using the premise that ions returning to the cathode from the microchannel plate (MCP) damage the cathode and reduce its sensitivity, a HeNe laser beam light source is raster scanned across the cathode of a microchannel plate image intensifier (MCPI) tube. Cathode current is monitored and when it exceeds a preset threshold, the sweep rate is decreased 1000 times, giving 1000 times the exposure to cathode areas with sensitivity greater than the threshold. The threshold is set at the cathode current corresponding to the lowest sensitivity in the active cathode area so that sensitivity of the entire cathode is reduced to this level. This process reduces tube gain by between 10% and 30% in the high gain areas while gain reduction in low gain areas is negligible.
Inventors:
 [1]
  1. (Livermore, CA)
Issue Date:
OSTI Identifier:
869841
Assignee:
Regents of University of California (Oakland, CA) LLNL
Patent Number(s):
US 5408087
Contract Number:
W-7405-ENG-48
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Country of Publication:
United States
Language:
English
Subject:
image; intensifier; uniformity; improvements; sealed; tubes; selective; scrubbing; microchannel; plate; intensifiers; mcpis; improved; selectively; sections; controlled; bright; light; source; premise; returning; cathode; mcp; damage; reduce; sensitivity; hene; laser; beam; raster; scanned; mcpi; tube; current; monitored; exceeds; preset; threshold; sweep; rate; decreased; 1000; times; giving; exposure; set; corresponding; lowest; active; entire; reduced; level; process; reduces; 10; 30; reduction; negligible; channel plate; image intensifier; light source; laser beam; microchannel plate; cathode current; beam light; active cathode; plate image; raster scan; raster scanned; image intensifiers; set threshold; bright light; /250/

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