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Performance was measured on an editing task which required counting the number of occurrences of an assigned letter in a paragraph of random letters. The task was presented in three different display modes: (a) a video display (VDT) with white characters on a black background, (b) a white-on-black photograph of the VDT display, and (c) a black-on--white photograph of the VDT task display. The viewing conditions for the three display modes were matched. Defocus was introduced by cylindrical lenses (simulated astigmatism) and by plus lenses. Performance was measured by time and accuracy in completing the counting task. There were 19 normally-sighted young adult subjects tested with the task in the three display modes under 6 levels of defocus.For the hard copy displays, performance was significantly faster (on average by 6.6%) for black characters on a white background. Performance with the black background photographs was consistently, but marginally (0.9%), faster than with the VDT displays. Cylindrical defocus of 1.50 diopters substantially impaired efficiency, but low-power plus lenses did not affect performance.

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Articles you may be interested inPerformances by the electron optical system of low energy electron beam proximity projection lithography tool with a large scanning field J. Vac. Sci. Technol. B 23, 2754 (2005; 10.1116/1.2062435 Stochastic Coulomb interaction effect in ion-neutralized electron-beam projection opticsElectron optical image correction subsystem in electron beam projection lithography Scaled measurements of global space-charge induced image blur in electron beam projection systemIn projection electron-beam systems resolution and throughput are linked through electron-electron interactions collectively referred to as space-charge effects. Hence, a detailed understanding of these effects is essential to optimizing the lithographic performance of a projection electron-beam lithography system. Although many models have been developed to describe one or more of the various aspects of the Coulomb interactions that occur in the beam, there is minimal experimental data available. We have performed a series of experimental measurements in the scattering with angular limitation projection electron-beam lithography ͑SCALPEL͒ proof-of-lithography system to characterize the space-charge effects for such an optical configuration. The results of those measurements have been compared to a combination of computer simulations and analytical models. The agreement between the models and experiments was good, within the limits of experimental error. We determined the exponent in the dependence of blur on beam current to be 1.029Ϯ0.16 ͑1͒, consistent with more recent models. Additionally, we comment on the use of blur modeling for system optimization.