The Use of Infra-Red Light for Video Surveillance Systems


13 March 2023

What is Infra-Red Light? 

Cameras, just like people, need light to see at night. Lighting plays a critical role in any security system achieving high-quality, reliable images. Raytec are lighting experts and have a wide range of options to choose from depending on the requirements and lighting objectives. 

Infra-Red light for video surveillance, sometimes referred to simply as ‘IR’, is a form of electromagnetic radiation which is invisible to the human eye. Within the electromagnetic spectrum, Infra-Red waves occur at frequencies above those of microwaves, and just below those of red visible light. 

Although we can’t see it with the human eye, Infra-Red light is actually all around us. All objects in the universe emit some level of IR radiation. While it may be invisible to the human eye, video surveillance cameras can detect Infra-Red light meaning it can be used to help the camera to see at night.



The Benefits of Using Infra-Red for Video Surveillance 

Because Infra-Red light is not visible to the human eye, it provides an ideal solution for covert surveillance. It allows the camera to achieve high quality images during night-time when there is little or no ambient light. Surveillance can be carried out without the need of additional visible light which could assist an intruder or notify them that they’re being watched.  

Infra-Red illumination is also an effective solution for applications where there is a concern for light pollution and the use of visible light may be considered obtrusive. 

Compared to visible light, Infra-Red has longer wavelengths that can travel through dust and moisture. This means the IR can be used to improve image quality compared to using White-Light, or relying on ambient light during daylight hours.  

Using VARIO2 Infra-Red, there is a clear difference between the quality of image when no light is used to illuminate the area. 

850nm vs 940nm

As shown in the image at the beginning of the article, Infra-Red waves span the electromagnetic spectrum between 700nm and 1mm. Within this range, there are generally two wavelengths of IR light which are most commonly used for security applications: 850nm and 940nm.  

850nm IR is the preferred choice for the majority of CCTV systems. Security cameras are most receptive to this wavelength of IR, meaning it can deliver longer distances and provides the camera with the best possible images. Sometimes referred to as semi-covert, an 850nm illuminator gives off a slight red glow, but this is only visible up close or when looking directly into the illuminator. This is due to the fact that 850nm is lower down the electromagnetic spectrum, closer to visible light wavelengths). For the majority of security applications this does not cause an issue. 

940nm is a fully covert wavelength of IR which does not emit any red glow from the illuminator. However, cameras are not as receptive to this wavelength meaning more light is required to achieve a high quality image. If possible, we would always recommend the use of 850nm over 940nm.

Raytec offer a wide range of Infra-Red illuminators as part of the award-winning VARIO2 range. VARIO2 illuminators deliver outstanding distances, and is available as a number of variants to suit different requirements. View the range here, or get in contact with our team of lighting experts to discuss your application – +44 (0) 1670 520055

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