Vehicle mounted cameras are becoming a staple in most professional security and law enforcement industries due to their ability to record every visual detail of events and incidents that these professionals might otherwise have difficulty making full note of. These cameras are making use of some very interesting technology that allows them to perform all sorts of video recording feats under a wide variety of conditions that would otherwise render video almost useless. One of the more interesting and useful ways security and law enforcement professionals overcome the shortcomings of standard video cameras is through the use of active infrared technology. Put simply, this is a way to provide illumination that although invisible to the human eye, is easily recorded by video cameras sensitive to the infrared end light spectrum.
Most modern video cameras use CCDs also known as Charged Coupling Devices to sense and sort the light coming through the cameras lens. These CCDs are generally sensitive to more than just the visible end of the light spectrum and can sense IR light as well. Manufactures compensate for this in some instances with filters that block out IR light in order to improve the cameras color resolution, but many still leave out such filters due to added costs. This means that many simple video cameras, whether they are the general home camera or professional grade equipment used by law enforcement and security professionals is capable of picking up images using IR illumination. Many manufacturers simply add a set of IR LEDs to their cameras or add a special filter and in effect create a camera that is then touted as low light or night imaging capable. There are, however, drawbacks to this.
Infrared light behaves the same as normal visible light. It is reflected off of objects, passes through transparent objects such as glass, and because of this can be used as a covert light source for devices capable of sensing it. IR light also has the same limitations as normal visible light; it can blocked by opaque objects and its reach is limited by its intensity and focus. Most camera manufacturers when offering IR capable systems include a small set of LEDs that are incorporated directly into the cameras design. When ambient light levels drop below a certain level or the operator manually triggers the low light option, these LEDs then emit IR light which the camera uses to create images in low or no light conditions. The problems encountered with this arrangement often center around the low power of the LEDs used. Because of their low power, the range and intensity of these built in LEDs limits the effective range of the camera in low light conditions as well. In addition, this low intensity IR light reduces the overall resolution of the images the camera creates, reducing the effectiveness with which the images can be used for positive identifications and record keeping.
The most obvious answer then is to increase the amount of available infrared illumination. Increasing the amount of infrared illumination has the same effect as adding additional visible light as far as the electronics within a camera sensitive to IR light is concerned. More available light means better resolution and greater visibility. Adding additional IR can be as simple as adding an auxiliary IR light source that is activated whenever the camera’s low light capabilities are switched on either automatically or manually. Depending upon the amount of light needed and the application, augmenting the cameras IR capabilities can be as simple as mounting an infrared LED emitter like a Larson Electronicss’ Infrared LED Light Emitter - 850nm or 940nm. Infrared emitters such as this can greatly improve the range and resolution of IR cameras many fold over the integral emitters they are equipped with.
With many security and law enforcement personnel tasked with monitoring oftentimes very large areas and requiring an ability to reduce the obtrusiveness of their presence, increasing the effective range of their surveillance equipment offers them this stealth and reach. Whereas the built in IR LEDs of a camera may have an effective range of only thirty to fifty feet, and auxiliary IR LED can extend that range into the hundreds of feet. And they can do this without any modifications or changes to the cameras already in use. As mentioned earlier, increasing the amount of IR light is the same to a camera as increasing the amount of visible light is to the human eye. More light means more visibility. Oftentimes these LEDs can be mounted directly to the camera itself, maintaining the systems portability and compactness if so desired.
Another consideration, however, is where within the IR light spectrum the LEDs produce their illumination. The most common range used in low or no light applications is 850nm. While this is adequate in most cases, these lights still produce a faintly noticeable red glow at the emitter. LEDs producing IR in the 940nm range, however, produce no visible light at all and represent the best option for applications that require the maximum amount of stealth possible. It is important to note before installation what the best recommended IR range is for the camera systems in question is to get the best results. What’s really great about adding an auxiliary IR source though is that any IR sensitive camera will be able to benefit. Whether it is a building mounted dedicated surveillance system or a vehicle mounted mobile system, adding an LED IR emitter will enhance and improve its capabilities.
One other issue here is control. Many low light capable camera manufacturers built an optional ability to connect auxiliary lighting systems right into their devices. With these systems, once the cameras IR capability is activated so is the auxiliary IR. Other systems can benefit by adding a dedicated switch or sensor that will allow manual or automatic activation whenever added IR light is required. Such modifications are generally straightforward and simple to perform although if an individual is unsure how to do this they are best left consulting with a professional. The benefits however outweigh what it would cost to change or upgrade an entire camera system, which makes adding a simple IR LED attractive not only practically, but financially as well.