Optical instruments aid your ability to see clearly in otherwise difficult environments. Humans, compared to other species, have significantly poorer night vision. In order to see clearly in the dark, some people use night vision goggles. Night vision goggles can produce images in the lowest levels of light. There are a few different types of night vision goggles available; each has its own set of advantages and disadvantages.
Passive Night Vision Goggles
Passive night vision goggles accumulate the ambient light within the user's general area, such as stars in the night sky. Through the use of embedded light intensifiers, the light is magnified several times over. The user then can view objects, other people, and their surroundings in great detail over a fairly long distance. The color green is used to display these images to the user. This color allows users to discern detailed images easier than they would with a brighter color such as red or yellow. Additionally, the green color helps the eyes to readjust to natural environments when the goggles are taken off.
Active Night Vision Goggles
Instead of using natural light as a source, active night vision goggles emit an infrared light source. An image is produced from the reflection of the infrared light. Because the light source is artificially produced, active night vision produces higher resolution images than their passive night vision counterparts. Commercial equipment such as home surveillance devices use this technology. The military shies away from using active night vision goggles, as the infrared light source can compromise the user's location.
Thermal Imaging
Thermal imaging goggles are night vision goggles that can function without any light. Thermal imaging goggles perceive thermal radiation. Thermal radiation is any radiation emitted from material due to the material's temperature. Thermal imaging goggles can see through total darkness, and weather obstructions such as rain, fog, and smoke, as long as the slightest amount of thermal activity is present. United States armed forces use thermal imaging devices when scanning a general area and acquiring a target.
Tags: light source, night vision, vision goggles, active night, active night vision, imaging goggles, infrared light
