Technology for low lighting imaging
RGB-InfraRed (RGB-IR) is a different filter type where one green spot in the standard Bayer Color Filter Array (CFA) is substituted with a spot which admits the Near-Infrared (NIR) wavelength to reach the sensor.
|Standard Bayer RGB CFA||RGB-IR|
This RGB-IR filter lets the sensor to be used as a standard color and as a NIR sensor. This is very useful in applications where the camera needs to be used in very different light conditions (i.e. day and night): during the night, the scene can be illuminated with a InfraRed light source which is only visible by the camera and not by the human eye.
The drawback of this technology is a loss of the quantum efficiency for the RGB wavelengths.
Here two quantum efficiency plots are taken from a sensor which shows the difference between a conventional Bayer CFA and an RGB-IR filter. As you can see, using the RGB-IR filter will slightly drop the quantum efficiency of the RGB wavelengths.