Night Vision Goggle Field-expedient Visual Acuity Adjustment Procedures
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Published: 1996
Total Pages: 54
ISBN-13:
DOWNLOAD EBOOKRead and Download eBook Full
Author:
Publisher:
Published: 1996
Total Pages: 54
ISBN-13:
DOWNLOAD EBOOKAuthor:
Publisher:
Published: 1996
Total Pages: 22
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DOWNLOAD EBOOKAuthor:
Publisher:
Published: 1996
Total Pages: 46
ISBN-13:
DOWNLOAD EBOOKThe 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.
Author: Jean L. Dyer
Publisher:
Published: 1998
Total Pages: 82
ISBN-13:
DOWNLOAD EBOOKAuthor: U.S. Army Research Institute for the Behavioral and Social Sciences
Publisher:
Published: 1994
Total Pages: 246
ISBN-13:
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Published: 2000
Total Pages: 248
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DOWNLOAD EBOOKAuthor: Arthur Bradley
Publisher:
Published: 1994
Total Pages: 44
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DOWNLOAD EBOOKAuthor: Harry L. Task
Publisher:
Published: 1994
Total Pages: 21
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DOWNLOAD EBOOKParameters typically used to characterize night vision goggles (NVG) are visual acuity (resolution) and field-of-view (FOV). An increase in FOV is accomplished by providing higher magnification of the image intensifier tube. However, increased magnification means that the pixels will subtend a larger angle, thus leading to lower NVG visual acuity. An inverse relationship between visual acuity and field-of-view is expected based upon this optical/geometrical relationship. This relationship should be examined as production of NVG resolution quality increases. A trade-off study examining FOV and resolution was conducted with three observers having 20/20 corrected Snellen acuity. The NVGs had fields-of-view of 40, 47, and 52 degrees, respectively. Five levels of ambient scene illumination (corresponding to output luminance levels of 0.01, 0. 03, 0.08, 0.26, and 1.4 ft-L) were provided by a 2856K light source. The targets used in the study were 95+% contrast square wave targets ranging in size from 45 cycles/degree to 5 cycles per degree. A walk-back method of adjustment was employed. The results indicate that the geometric relationship between field-of-view and visual acuity is valid. Night vision devices, Visual acuity, Night vision goggles.