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In order to take full advantage of the telescope resolution, both the pair of MCPs in the detector and the resistive anode readout system are curved, like a watchglass, to match the optimum focal surface. A CsI photocathode is deposited directly onto the front face of the front MCP to enhance the EUV quantum efficiency.   The detector spatial resolution is substantially (a factor >2) better than that of the mirror nest and consequently does not contribute significantly to the net performance of the WFC. A focal plane turntable can be used to select one of two identical detector assemblies in flight. Table 6.2 gives details of the detectors.



Diameter tex2html_wrap_inline17875
Active diameter tex2html_wrap_inline17877
Radius of curvature tex2html_wrap_inline17879
Channel diameter tex2html_wrap_inline17881
Channel pitch tex2html_wrap_inline17883
Open area 63%
Length-to-diameter ratio 120:1
Front MCP bias angle tex2html_wrap_inline17885
Rear MCP bias angle tex2html_wrap_inline17887
Photocathode (front MCP only) tex2html_wrap_inline17889 CsI
Table 6.2: WFC detector characteristics

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