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Proceedings Paper

Night vision goggle luminance disparity and the Pulfrich phenomenon
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Paper Abstract

When night vision goggle (NVG) image intensifier tubes (I2Ts) are replaced during maintenance, the output luminances of the two channels must not exceed a ratio of 1.5 (brighter channel luminance divided by the dimmer channel luminance) in order to meet the current allowed binocular luminance disparity specification. Two studies were performed to investigate the validity of this requirement. The first study estimated thresholds of binocular luminance disparity detection for observers looking through NVGs. For eight observers, the 25% corrected-for-chance probability of detecting an ocular luminance difference, yielded an average ratio of 1.43 indicating that the current 1.5 specification is perhaps too loose. The second study investigated the Pulfrich phenomenon, a pseudo-stereo effect that can be induced by presenting luminance imbalances to the eyes. This study created NVG luminance imbalances using neutral density (ND) filters and then investigated whether or not the various imbalance levels were sufficient to cause the Pulfrich phenomenon to be perceived. Results indicated an imbalance ratio of 1.10 was insufficient to cause the effect to be seen, but a ratio of 1.26 was sufficient (p ≤ 0.0003) for the effect to be seen, at least part of the time. Based on these results, it is apparent the allowed binocular luminance disparity ratio should probably be tightened to at least 1.3 with a goal of 1.2.

Paper Details

Date Published: 8 September 2004
PDF: 10 pages
Proc. SPIE 5442, Helmet- and Head-Mounted Displays IX: Technologies and Applications, (8 September 2004); doi: 10.1117/12.540703
Show Author Affiliations
Alan Pinkus, Air Force Research Lab. (United States)
Harry Lee Task, Task Consulting (United States)

Published in SPIE Proceedings Vol. 5442:
Helmet- and Head-Mounted Displays IX: Technologies and Applications
Clarence E. Rash; Colin E. Reese, Editor(s)

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