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. 4 figs.
- Issue Date:
- OSTI Identifier:
- 46323
- Assignee:
- Univ. of California, Oakland, CA (United States) PTO; SCA: 426000; PA: EDB-95:078397; SN: 95001384532
- Patent Number(s):
- US 5,408,087/A/
- Application Number:
- PAN: 8-129,731
- Contract Number:
- W-7405-ENG-48
- Resource Relation:
- Other Information: PBD: 18 Apr 1995
- Research Org:
- University of California
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES; IMAGE INTENSIFIERS; GAIN; LASER RADIATION; HELIUM-NEON LASERS; IMAGE TUBES; PERFORMANCE; ELECTRIC CURRENTS