Infrared – 850nm VS 940nm
The Human Eye’s Sensitivity to Infrared Light
The human eye can see the light wavelengths in the range of about 380nm to 700nm. Light above 700nm in the infrared spectrum (IR Light) is not visible to the human eye. The shorter “near-infrared” wavelengths, which are closer to visible light, from about 700nm to 900nm, can appear as a faint red glow when looking directly at a high powered IR LED source. However, it is invisible to human eye as “light” that illuminates other objects.
Security Camera Sensitivity to IR Light
Most security cameras have sensors which are sensitive to the IR wavelengths that are invisible to the human eye. This is why IR light (IR illuminators) are used to enhance security camera performance in low-light and at nightime. Since infrared is invisible it can be used without causing light pollution and/or covertly. Images a security camera captures using infrared light will be black & white, only full spectrum “white” light can produce color images. If both invisible IR surveillance and colored image capture are needed, AXTON Hybrid lights are a good option.
IR Illuminator Wavelengths – 850nm compared to 940nm
The most commonly used infrared wavelength for security camera lighting is 850nm IR, it provides best performance versus invisibility balance. Although 850nm IR is invisible to the human eye as “light”, it does produce a slight red glow at the LED light source. For this reason, it is not suitable for covert surveillance applications, such as those for Government or Law enforcement. For covert surveillance, 940nm IR light is recommended, because it is completely invisible to humans, even at the light source.
Even high powered 940nm IR illuminators produce no source red glow. However, 940nm IR may have up to 50% less range than 850nm IR does. Also, security cameras are not as sensitive 940nm as they are to 850nm IR. This is why 850nm IR is used for most long-range security applications, with a longer range, any slight red glow at the lights source will most likely not be noticed. When considering the advantages in expanded coverage range and camera sensitivity, 850nm is usually the best choice for medium to large Security applications.
For applications when total invisibility is required or for small spaces, an 940nm IR illuminator is a good option. Before choosing a 940nm IR illuminator, please check your cameras specs, to make sure it is sensitive to the 940nm IR wavelength.
AXTON’s Tactical series 940nm IR Illuminators are completely covert, invisible to the human eye even at the light source. Tactical Illuminators are available in several models, including: PoE powered, Solar/Battery powered, Compact NANO and Indoor IR Fixtures, more: Tactical IR Illuminators.
