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22 August 2001 Measurement of visual performance through scattering visors and aerospace transparencies
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Light scattered from helmet visors and aerospace transparencies is known to reduce visual performance. One popular measurement technique, maintained by the American Society for Testing and Materials, is ASTM D 1003. It is a standard procedure used to measure haze inherent in transparent materials, which is defined as the percent of the total transmitted light that is scattered. However, research has shown that visual acuity measured through several different types of helmet visors does not correlate well with visor haze. This is most likely due to the fact that the amount of light scattered from a transparent material depends heavily on the light illuminating the transparency and on the viewing geometry, behavior that ASTM D 1003 does not characterized. Scattered light causes transparent parts to appear luminescent and imparts a veiling luminance when superimposed over a target, reducing target contrast and inducing a visual performance loss. This paper describes an experiment in which threshold target background luminance, the luminance at which a target was barely visible, was measured for a number of observers viewing a Landolt C target through several levels of veiling luminance. Threshold luminance was examined for predictable behavior with respect to veiling luminance.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Peter L. Marasco and H. Lee Task "Measurement of visual performance through scattering visors and aerospace transparencies", Proc. SPIE 4361, Helmet- and Head-Mounted Displays VI, (22 August 2001);


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