How Infrared Cctv Cameras Work

By Author: Ray Shadman
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When it comes to video surveillance security applications, it's easy to see why night-vision-the ability to see in the dark-could be a significant bonus. Infrared closed-circuit television cameras make this a reality, effectively monitoring the darkness for your surveillance system. Even though we've seen countless examples of thermal imaging in film ever since Predator first hunted Arnold Schwarzenegger and company, we still wonder how does this technology work? What is it that allows an infrared CCTV to see clearly in the dark?

Thermal Imaging
The process used by infrared CCTV cameras for night-vision is known as thermal imaging. People and objects constantly emit a level of heat referred to as thermal energy. Thermal energy resides in the electromagnetic spectrum which in turn occupies the top of the infrared light spectrum. Thermal energy is invisible to the naked eye because it is emitted from a source, as opposed to being reflected by light.

Infrared CCTV cameras use thermal imaging to capture various levels of thermal energy and convert it to a light-based image that is visible to the human eye. ...
... This process of revealing the invisible occurs over several steps:

A. Infrared Lens
The specially designed lens of an infrared camera is used to focus the levels of invisible infrared radiation within its view.

B. Thermogram
Infrared detectors review the radiation focused by the lens and proceed to create a temperature map known as a "thermogram." The completed thermogram is then translated into a series of electric impulses.

C. Signal-Processing
Once converted into electric impulses, the thermogram is sent to a chip on the camera or server known as the signal-processing unit. This unit rebuilds the electric impulses as usable data.

D. Display
Once translated, the usable data is sent to the display, where it is appears as a graphic rendition of the contrasting heat emissions that were originally captured. These images exist in the visible spectrum, allowing the human eye to see the subject via its own thermal energy.

Cooled or Uncooled
Most infrared cameras fall into the "uncooled" category, meaning that camera is not equipped with any kind of onboard cooling mechanism. Cryogenically cooled infrared cameras, on the other hand, are higher-end devices featuring a sophisticated cooling device. Although this variety of camera is considerably more expensive than the more common uncooled versions, it provides the camera with an extremely high level of sensitivity to thermal energy variations. This means that cryogenically cooled infrared CCTV cameras can receive a much finer range of information, resulting in images with much more detail and depth.

In the Dark
Because infrared CCTV cameras draw all of their images from a person or object's level of infrared radiation, their performance and image quality is in no way affected by light. Whether covering an area engulfed in darkness or filled with blindingly bright lights and flares, an infrared CCTV camera will always perform at the same level.

Advantages of Infrared CCTV Cameras
In addition to providing reliable video monitoring regardless of lighting conditions, infrared cameras boast other useful features. An infrared CCTV camera equipped surveillance system can help alert you if anything is amiss by highlighting things about your surroundings that would be invisible to the naked eye. For example, if a wall or object were secretly damaged and repaired, the level of thermal radiation coming from the area in question would be lower and therefore darker than its surrounding emissions. This feature is not only useful for surveillance applications but has obvious military and law enforcement uses as well.

In fact, infrared cameras were initially developed as a means for the military to detect hidden targets. But it didn't take long for the commercial and private sectors to find a multitude of uses for the technology. Today, infrared cameras have applications ranging from traditional security, surveillance, and military to things like hunting, navigation, and even treasure hunting and paranormal investigation.

While this technology can be preferable to a standard CCTV camera in many situations, the once sky-high prices for thermal imaging-based applications are dropping dramatically with the rapid proliferation of infrared CCTV cameras. If you've ever had a need to see in the dark, now is the time to look at what infrared closed-circuit televisions can offer you.
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