Night Vision Security Cameras - Catch Them In The Dark

Night vision cameras are cameras having “eyes” to see in poorly lit or dark conditions objects that would not be visible to the human eye. Unlike ordinary cameras, which use visible light to capture images, night vision cameras use the invisible, infrared part of the electromagnetic spectrum to produce images. This explains their use in night security camera surveillance. A good quality night vision security camera, for example, can make visible a person standing 200 meters away on a moonless cloudy night.

What is the purpose of a night vision security camera?

The main purpose of a camera night security vision is obviously monitoring human activity in poorly lit or dark regions in the vicinity of your business.

Even inside the well-lit premises of an office or a manufacturing unit working overnight, installing wireless camera night surveillance vision at crucial locations is a wise policy because catching offenders who may try to sabotage your business by first incapacitating the electrical lighting system becomes easy.

In some instances, one of the employees may try to steal some confidential documents or important information by switching off the lights and using a miniature torch instead.

Various types of night vision cameras and their uses

Security cameras night vision is of two types depending upon which part of the infrared spectrum they utilize for imaging.

An image enhancement type of infrared camera works by effectively enhancing and amplifying the normally imperceptible-to-the-eye image of an object. The image is formed by gathering minuscule amounts of light reflected by the object - when whatever amount falls on it from the near-dark ambience - along with some reflected radiation from the lower-wavelength, higher-frequency part of the infrared spectrum (lying immediately next to the red part of the visible spectrum but not picked up by a normal camera). This image is then amplified to a level that it becomes visible to the human eye.

Note that the working of this type of camera is similar to a normal camera in the sense that both use the light (whether infrared or visible) reflected by the object.

A thermal imaging night vision camera, on the other hand, employs the blackbody heat radiation spectrum of the object. Blackbody radiation is the thermal, or heat, radiation emitted by all objects by virtue of their being at a finite temperature (on the Kelvin scale). This emitted heat radiation lies in the higher-wavelength, lower-frequency part of the infrared range, away from the visible part of the electromagnetic spectrum.

Hotter objects, e.g. human bodies, emit more of this radiation than cooler objects, like the surrounding trees, water bodies, and buildings. It is because of these differentials in temperature that a thermal imaging camera is able to pick up images. The thermal image is then processed by the camera to yield a visible image. For example, the brightest (in other words, the warmest) parts of the image would show up as white, intermediate temperatures would show up as reds and yellows, and the dim faintest (in other words, the coolest) parts would show up as blue.

A thermal imaging camera is also called a thermo graphic camera or an FLIR (Forward Looking Infrared) camera. The most attractive advantage of thermal imaging cameras is that they can operate in absolute darkness, because ambient light does not come into picture at all. It is the pattern of the body heat of the object that is mapped to ultimately create its image.

There also exist wireless versions of night vision cameras, which have additional advantages of the wireless technology.

Advantages and disadvantages of night vision security cameras

First the advantages:

• Infrared cameras are easy to install and adaptable to a variety of situations.
• They help monitor security in areas not accessible to the human eye.
• Their versatility can be enhanced drastically using advanced optics and sophisticated software interfaces.

Now the disadvantages:

• The resolution of infrared cameras is considerably lower than that of optical cameras.
• They are much more expensive than their visible-spectrum counterparts.
• The image is not shown in true colors because different infrared wavelengths do not always map uniformly into the color vision system of the human eye.

How to choose the right night vision camera for your office

Before you choose a night vision security camera for your office, it is important to understand exactly your requirements. And also what all is available in the market. For example:

• Whether you need a day/night camera or only night vision camera. The former type camera works as a normal color camera during the day and automatically switches to black & white or green phosphor shades at night in order to yield optimum performance under poor lighting conditions.
• What kind of Lux rating you would require for your night vision camera. (Lux rating refers to the minimum illumination required for a camera to be able to capture images.) The closer the Lux rating of a camera is to zero, the better would be its performance for nighttime security.
• Whether you need the camera for indoor or outdoor application.
• Whether you need a low-resolution or a high-resolution camera.
• Whether you want a static model or a PTZ (pan, tilt, zoom) model.

Commercially available cameras come in various categories of price range, complexity and efficiency, from the relatively inexpensive, simplest ones - called Generation 1 night vision cameras - to the most advanced and sophisticated, and high-priced models fit enough to be used for military applications - called Generation 4 night vision cameras. So you have to decide which generation of night vision cameras suits your security needs and your pocket.