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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722214555
Category :
Languages : en
Pages : 42
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Book Description
Using laboratory simulations, visual performance was measured at luminance and night vision imaging system (NVIS) radiance levels typically encountered in the natural nocturnal environment. Comparisons were made between visual performance with unaided vision and that observed with subjects using image intensification. An Amplified Night Vision Imaging System (ANVIS6) binocular image intensifier was used. Light levels available in the experiments (using video display technology and filters) were matched to those of reflecting objects illuminated by representative night-sky conditions (e.g., full moon, starlight). Results show that as expected, the precipitous decline in foveal acuity experienced with decreasing mesopic luminance levels is effectively shifted to much lower light levels by use of an image intensification system. The benefits of intensification are most pronounced foveally, but still observable at 20 deg eccentricity. Binocularity provides a small improvement in visual acuity under both intensified and unintensified conditions. Bradley, Arthur and Kaiser, Mary K. Ames Research Center ...
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722214555
Category :
Languages : en
Pages : 42
Get Book Here
Book Description
Using laboratory simulations, visual performance was measured at luminance and night vision imaging system (NVIS) radiance levels typically encountered in the natural nocturnal environment. Comparisons were made between visual performance with unaided vision and that observed with subjects using image intensification. An Amplified Night Vision Imaging System (ANVIS6) binocular image intensifier was used. Light levels available in the experiments (using video display technology and filters) were matched to those of reflecting objects illuminated by representative night-sky conditions (e.g., full moon, starlight). Results show that as expected, the precipitous decline in foveal acuity experienced with decreasing mesopic luminance levels is effectively shifted to much lower light levels by use of an image intensification system. The benefits of intensification are most pronounced foveally, but still observable at 20 deg eccentricity. Binocularity provides a small improvement in visual acuity under both intensified and unintensified conditions. Bradley, Arthur and Kaiser, Mary K. Ames Research Center ...
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 46
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Author: Arthur Bradley
Publisher:
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Category :
Languages : en
Pages : 44
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Category : Night fighting (Military science)
Languages : en
Pages : 54
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Author: Peter Demitry
Publisher:
ISBN:
Category :
Languages : en
Pages : 22
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Of all man's senses, vision is recognized as the most critical for aviators to safely fly their aircraft (Tredichi, 1985). Since the introduction of night vision goggles (NVGs), night operations continue to become more demanding as aircrews continue to expand the night operational envelope. As mission variety expands, hazards likewise multiply allowing decreased margins for distraction, error or disorientation without deadly catastrophic consequences. NVGs provide an intensified image of night scenes illuminated by ambient energy in the red and near-infrared portion of the electromagnetic spectrum, which is abundant in the night sky. The intensified imagery is roughly 2,000 to 7,000 times brighter than the original scene, depending upon the type of intensifier tube used, and provides the user with a field of view ranging from 30 - 45 degrees (Kotulak & Rash, 1992). The explosion of NVG users attests to the fact that this technology greatly enhances the ability to conduct night operations. Goggles are used extensively in both rotary and fixed- wing aircraft. Law enforcement, immigration service and military aircrews increasingly rely on night vision devices when darkness restricts normal vision. NVG & work best when the ambient illumination is relatively intense (e.g., full moon) and the contrast of the scene is high. However, scene rendering is significantly degraded when ambient illumination decreases and/or scene contrast decreases (Kotulak & Rash, 1992).
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Category :
Languages : en
Pages : 46
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The third-generation image intensification technology in night vision goggles (NVGs) used by ground forces provides at best 20/40 or 20/45 visual acuity. These acuity levels cannot be achieved unless soldiers adjust their NVGs properly. Documentation available to soldiers does not address optimum adjustment techniques developed by the aviation community nor does it address what can be used in the field to achieve a good setting. We examined the effectiveness and utility of 15 different objects commonly available to soldiers to determine which provided the best visual acuity readings with the AN/PVS-713 NVGs. After training and practice acuity improved by 25% over the baseline assessment. No large differences in readings occurred among the objects. However, a more definitive picture emerged when the average readings were combined with measures of variability and soldier preferences. The initial recommendation is to use one of the following objects for NVG adjustment: trec trunk, vehicle, vehicle trail, stars, blue chem light, or an infrared chem light. Not recommended are bright and/or red light sources, white paper, and trees silhouetted against the night sky. Problems in assessing acuity with NVGs are also discussed.
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Category :
Languages : en
Pages : 43
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The purpose of this investigation was to study the primary factors which influence visual acuity (VA) with night vision goggles (NVGs). These factors are: night sky condition, target contrast, and NVG generation. Improved methods were used to simulate the night sky and to control for differences in target contrast which result from dissimilarities in spectral sensitivity between NVG generations. The new simulation method used combinations of spectrally flat (neutral density) and wavelength selective (blue glass) filters to reproduce the spectral distribution of the night sky across the entire NVG response range. Between-generation differences in target contrast were eliminated by weighting the incident radiant flux by the sensitivity of the detector. It was found that the difference in VA between the two generations widens under two conditions: (1) when target contrast is constant and night sky irradiance decreases, and (2) when night sky irradiance is constant and target contrast decreases. Furthermore, it was found that for a given NVG generation, VA falls off more rapidly for a low contrast target than for one of high contrast when night sky irradiance decreases.
Author: Randall William Gibb
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Category : Night flying
Languages : en
Pages : 158
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Category : Aeronautics
Languages : en
Pages : 702
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Category :
Languages : en
Pages : 457
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