Thermal imaging cameras work by detecting and measuring infrared radiation, known as heat signals, emitted by objects. To do this, a thermal imager must first be equipped with a lens that can pass infrared frequencies. The lens can focus infrared frequencies onto a special sensor array to detect and read those frequencies.
The sensor array consists of a grid of pixels, each of which responds to incoming infrared wavelengths and converts them into electrical signals. These signals are then sent to a processor in the body of the camera, which uses algorithms to convert them into color images with different temperature values. This colormap is then sent to the monitor.
Many thermal imaging cameras also include a standard form of photography for the visible spectrum, similar to a one-button digital camera. This makes it easy to compare the same lens in infrared and general form; this helps to quickly identify specific problem areas once the user moves away from behind the lens.
The use of thermal imaging cameras
People often ask about the use of thermal imaging cameras in specific situations and the effectiveness of the technology in specific environments or applications. Let's look at the problem.
Why do thermal imaging cameras perform better at night?
Infrared cameras generally perform better at night, but this has nothing to do with the brightness of the surrounding environment.
Since the ambient temperature at night (and importantly the temperature of unheated objects and the center of the environment) is much lower than during the day, thermal imaging sensors can show warm areas with higher contrast.
Even on cool days, the sun's heat is absorbed by buildings, roads, vegetation, building materials, etc. During the day, various objects absorb heat at ambient temperature. The difference between these objects and other warm objects to be detected is not very noticeable when using thermal imaging sensors for detection.
Likewise, if you're in the dark for a few hours (not after the sun has set), most thermal cameras will clearly show warm objects; even during the day, early morning is more visible than noon.