Reduction of veiling glare in electro-optical image tubes

Several techniques for measuring veiling glare in image tubes are identified and the merit of each discussed. The half-field method is determined to be most advantageous and a detailed discussion of this method is included. Veiling glare is described in two regions having different slope of intensity profile away from the half-field terminator. The more sharply falling region is identified as near-field veiling glare and the nearly constant background extending essentially over the full dark field is the far-field veiling glare. Because of observation limitations, near-field veiling glare values have probable error as high as plus or minus 50%. Four types of image tubes were fabricated and evaluated for veiling glare characteristics. The emphasis was to determine the effectiveness of blackening of internal surfaces as a means of reducing veiling glare.