A night vision device (NVD) is an optical instrument that allows images to be produced in levels of light approaching total darkness. They are most often used by the military and law enforcement agencies, but are also available to civilian users. The term usually refers to a complete unit, including an image intensifier tube, a protective and generally water-resistant housing, and some type of mounting system. Many NVDs also include sacrificial lenses, IR illuminators, compasses and telescopic lenses. The technology has evolved greatly, leading to several "generations" of night vision equipment with performance increasing. Night vision goggles, also known as night vision devices (NVD), are used to see in environments that contain light levels that would otherwise prohibit human sight, i.e., very low levels of light.

There are two types of night vision devices: passive and active. Passive systems use naturally produced ambient light. Active devices use infrared light, which is on a different part of the light spectrum. They work by detecting and amplifying natural ambient light often produced by the moon or stars, amplifying the light using an intensifier tube and the photoelectric images are displayed on a phosphor screen. The human eye can detect wavelengths of 400 to 700 nanometers. Passive night vision devices operate in a band on the light spectrum that has a wavelength of roughly 1 micrometer while active (infrared) night vision devices operate in a spectral range from 700 nanometers to 100 nanometers, which is just beyond what the human eye can detect. For any additional information and for any orders, please feel free to contact us.