Different Types of Night Vision Devices

Passive Starlight Scopes

Starlight or passive night vision scopes use very large objective lenses, and are often considered the simplest and cheapest versions of night vision devices; however there are more expensive versions of the passive starlight scopes which are coated in multiple layers of a special chemical. The lenses which are coated with this chemical allow them to transmit up to 95% of the light back towards you, the viewer. A passive starlight scope captures any available light, whether it is moonlight, starlight, low level sunlight, or even a streetlamp, and condenses it to a smaller area, pushing up the photons per square millimeter, and resulting in a much brighter image. If you are in pitch black darkness of night, the passive starlight is really of no help at all; if you are planning on night hunting or night surveillance, you will need true night vision goggles, binoculars, or scopes. However, if your goal is simply to see in low light, such as dusk, moonlight or dawn, passive starlight scopes can be a good solution, plus there are no electronics involved which can malfunction and require power. Passive starlight scopes are silent and portable, and extremely good for early morning or evening nature watching. Some passive starlight scopes now have infrared projectors, which illuminate your target with a near-invisible source of light, allowing you to effectively see in the dark.

Active Starlight Scopes

Active starlight scopes work on the principle of there being at least a certain amount of light available. The active starlight scope magnifies this minute amount of light, making the image clearer than it would be if viewed by the naked ide. The active starlight scope must have power, which makes it somewhat useless if you plan on going out into the outdoors-further than your backyard, where an extension cord is available.

Active Infrared Scopes

An active infrared scope takes the infrared light which is out of our human viewing range, but exuded by most everything that surrounds us at night, and coverts it into something visible to the human eye. The operation of an active infrared scope is somewhat similar to that of a regular scope, except that the active infrared night device picks up streams of infrared wavelength photons, rather than regular light, and converts them to a phosphor image. Although this type of technology is very expensive, it does render you the ability to see in absolute darkness.

Image Intensifiers

All available light sources are used in image intensifier technology, both that which is visible to our human eye as well as that which is not. All of these lights are combined to produce excellent results, but are generally possessed only by the military due to their extravagant price range. An image intensifier tube is essentially a vacuum tube which increases the intensity of available light to enable the human eye to be able to see in low-light situations. At present there has been only one successful fourth generation tube using these image intensifiers, which uses the same photocathode as the Generation-3, however does not use the ion-barrier film and can also be used in high-light environments such as daylight.

Night vision technology continues to evolve, and we can likely expect the technology to go down in price as more advanced technology takes its place.