850nm VS 940nm, what is the difference?

Infrared radiation (IR) which is often known as infrared light uses wavelengths that are longer than those of visible light. This makes them almost invisible to the human eye (covert IR).

 

IR wavelengths are measured in nanometers (nm) which are used to specify the wavelength of electromagnetic radiation near the visible part of the light spectrum, these wavelengths can go up to a maximum of 1050nm. 

 

850nm, where is this used?

The 850nm wavelength is used in most applications. When we supply IR CCTV cameras they will generally use 850nm. The 850nm performs very similarly to the 940nm wavelength however they both come with their positives and negatives. 

The 850nm wavelength will produce a slight red glow when looking at the camera. This red glow can be mistaken for a signal and therefore not suitable for covert situations. Most cameras with an IR cut filter have a greater sensitivity to 850nm wavelength and this is why they are used for IR illumination/night vision. 

 

red glow vs covert IR

 

940nm, where is this used?

The 940nm wavelength is often referred to as 'covert IR', this is due to the wavelength not producing any visible glow. Any application that requires a covert camera will use the 940nm wavelength and this will also be used in applications where a red light is interpreted as a signal. 

 

With covert IR comes its disadvantages. The illumination range of the 940nm is 30-40% shorter than that of the 850nm wavelength. This often means that anything over 5M begins to blend into the background and picture becomes quite difficult to view. 

 

850nm vs 940nm

 

Posted in News By

Chris Bird