Evaluation Of Visual Acuity With Gen Iii Night Vision Goggles PDF Download

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).