How Does Night Vision Work?

Night scopes are used to intensify human sight, even in very low light conditions; there are infrared imaging systems, or "active" night vision devices which focus infrared light on a scene. Infrared is beyond the light spectrum visible to humans, making the beam undetectable. Image converting technology transforms the infrared scene into an image visible to the human eye. Thermal imaging systems work in much the same way as infrared, meaning it converts the pattern of heat which is constantly emitted by objects, people, or animals into a visual image. The night vision devices which were originally used in wartimes and are now known as "passive" night vision systems, amplify images picked up in minimal light, such as starlight or moonlight, turning them into visible images. The view you see through a passive night vision device can be from 20,000 to 50,000 times brighter than what your naked eye can see.

Different Types of Infrared

You must understand a certain bit about light in order to fully understand night vision technology. Short wavelengths come with higher energy, and the amount of energy in a light wave is directly proportional to its wavelength. Violet has the most energy of visible light, while red has the least energy. Next to the visible light spectrum is the infrared light spectrum, which is essentially split into three categories. Near-infrared is the closest thing to visible light, with wavelengths ranging from 0.7 to 1.3 microns, while mid-infrared has wavelengths ranging from 1.3. to 3.0 microns; mid-infrared technology is used in a variety of electronic devices, including remote controls. Finally, thermal-infrared occupies the largest part of the infrared spectrum, with wavelengths ranging from 3 microns to over 30 microns. The major difference between thermal infrared and near and mid-infrared is that thermal infrared is emitted by an object rather than reflected off it. Infrared light is emitted due to what is happening at the atomic level.

Active Infrared Scopes

The infrared night vision scope intensifies available infrared light which we as humans cannot see, yet is given out by most everything surrounding us in the night. The device then takes this infrared light and converts it into something visible. Infrared scopes are similar to a regular scope except that the infrared night vision device picks up streams of infrared wavelength photons-not regular light-and converts them into a phosphor image, rendering them way more expensive, but giving you the ability to see in absolute darkness

In Short....

The basic principle of night vision lies in the fact that the incoming photons strike a photoelectric plate which reacts by releasing a number of electrons for each photon that strikes it; the electrons are then accelerated through a photomultiplier, producing even more electrons and propelling them down a tube where they strike a phosphor screen which reacts by creating pools of light, visible to the human eye. Night vision scopes continue to improve in sharpness resolution, and, although they can be fairly expensive, an avid hunter may find the cost well worth it.