NON-BLOOMING IMAGE ORTHICON.
Rept. no. 6 (final), 1 Jul 63-31 Jan 65,
WESTINGHOUSE ELECTRIC CORP ELMIRA N Y ELECTRONIC TUBE DIV
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A development program is presented for an image orthicon with a thin-film target and a trialkali photocathode, with the capability of handling very high spot-illuminations in scenes of low general illumination. The Non-Blooming Image Orthicons developed had the standard electroformed target-mesh replaced by a thick collector-mesh and a fieldmesh spaced 1 mm from the target. Major problems encountered that limited the investigation were target breakage and non-uniform electron penetration through the collector-mesh. Blooming measurements were performed with a special test-chart. Tubes were made that demonstrated only 1 loss in video information with spot-illumination at the photo-cathode at the 0.00001 foot-candle level. These figures are applicable only to measurements made with this test-chart, and substantially lower ratios are to be expected with real or simulated scenes of less than 100 contrast and bright spots of larger relative area. The best non-blooming characteristics were observed on thick-collector-mesh image orthicons with an integral target-field-mesh.