Vision of night
The expressions vision of night or night vision can indicate;
capacity with naturally seeing in the black
It can be a question of an animal (the owl or the lynx for example, which are animals night or semi-night) or the human being (poor vision in the black night).Cette capacity depends on a particular type of cells of the Oeil, located in the Rétine (the cells in stick, which are more sensitive to the light, and connected to part of the brain more sensitive to the movements, in particular those perceived in the side field of vision, but which do not perceive the Couleur S. They are also much more sensitive to the dazzling)
An artificially assisted vision
It east is used as detection or observation aid to see in the black or the semi-darkness. They are binocular, monocular binoculars or materials of the glasses type allowing more brought closer sight. They are generally materials based on the electronic amplification of Lumière, used on the aircraft, the boats, like in the Infanterie of some Armée S, or by various police force.There exist three types of vision of night:
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Intensifier of light: it makes it possible to see in the darkness by amplifant the sources of light weak (the Moon, star S). One amplifies the photons detected (coming from ambient light) on the principle of the Photomultiplicateur.
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Near Infra-red: the syteme is equipped with a Diode emitting in the infra-red close relation and who allows to light the scene of rays nonvisible with the eye. This system makes it possible to see in the total black. To note that on certain models infra-red LED is visible when it functions. The diode can be separate material of vision, and to be used like directionally like one does it of a flashlight.
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Thermal Vision : the system is sensitive to the thermal radiation of the objects and the scene. The levels of gray returned to the screen translate the Température each object (when it is about an image in black and white).
Un system of graduation by colors is often used on the screens of thermic analyzes for a better visual analysis of the scene observed. The vision is the same one of day or in the total black.
See too
- scotopic Vision
- night Nyctalopie
- Environment
- luminous Pollution