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Night Vision Goggle Assessment Techniques with Incompatible Cockpit Lighting and a Modified Class B Goggle.

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Master's thesis,

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Visual acuity VA is the standard form of measuring visual performance among pilots in the U. S. Air Force. Yet, during cockpit light evaluations using night vision goggles NVGs, it has been noted that VA remains constant despite noticeable loss in apparent visual contrast. Therefore, contrast sensitivity CS may be a useful measure of visual performance under degraded viewing conditions. The objective of this research was to demonstrate that CS is a viable, additional visual performance tool in NVG cockpit light compatibility evaluations. This study investigated both NVG-aided CS and VA performance with incompatible cockpit lighting. Green and red lights, used in NVG compatible cockpits, were used to accomplish the degradation from a baseline or no-light condition. The lights were placed directly in the NVG field of view FOV. Twenty subjects were assessed under three light conditions. The subjects viewed three newly developed NVG CS charts and two VA charts. The 3 CS charts had spatial frequencies of 3, 6, and 12 cycles per degree cpd and 16 levels of decreasing contrast. The two VA charts were the NVG Resolution chart and the USAF 1951 Tri-bar chart. The type of NVG used contained a new NVG Class B filter, which enables a pilot to view the heads-up display HUD. The CS charts proved to be an effective tool in evaluating an incompatible cockpit light. The two different VA charts were compared and found to produce the same VA scores in all conditions. The combined assessment procedures of CS and VA provided an accurate visual performance assessment of an NVG under an incompatible light. The modified Class B filter demonstrated that it meets all the cockpit lighting requirements of the military specifications.

Subject Categories:

  • Anatomy and Physiology
  • Optical Detection and Detectors
  • Non-Radio Communications

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