Shedding Some Light on Infrared Illumination
Filed under: CCTV Articles, CCTV Camera, General Technology, IP Cameras, Security Camera
Let’s talk a little bit about infrared (IR) lighting. When confronted with low to no-light situations, infrared cameras are the common go-to for a quick and easy fix. But peel the layers of the onion back, and understanding camera sensors and infrared lighting becomes a much more complex matter.
Camera sensors are made up of two main materials: germanium and silicon – the material used will factor how the lens will react to light. An interesting note – many of the sensors which CCTV cameras use are actually manufactured by camcorder makers. Camcorder makers invest a good deal of time and money to develop a sensor that operates within the spectrum of light that our eyes can see. The human eye can see light in the approximate wavelength spectrum of 380nm to 760nm. Infrared light is considered any light wave length above 715nm. This leaves approximately 45nm of IR light spectrum we can see, which is why you can see a red glow around the lens at night.
One interesting thing to note about camera sensors is that all sensors are monochrome (use the grey scale, or are in black and white). Color is achieved by inserting a red, blue, and green filter in front of the sensors. These filters lead to a drop in resolution and quality in image over the monochrome image. Also, with the filters in place, the camera cannot view IR lights. Despite this, there are dual-mode cameras that can do both color and monochrome. When the light sensor detects the light dropping below a certain lux, the camera will remove the filters and turn on the IR lights. The image will go from color to black and white.
Despite other technological advancements in night vision, like Sense-up, infrared lighting remains king when you need to see in the dark.
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