Thermal screening devices use infrared technology to display the surface temperature of the observed object. The infrared light is invisible to the naked eye, but the special sensors installed in this device are designed to capture different levels of it.
Heat is transferred in several ways, infrared radiation being one of it. A scalding tea, for example, emits a considerable amount of infrared radiation – if you touch the tea with your finger, the heat is transferred to it.
The amount of radiation produced is proportional to the heat of the object – the hotter the object, the more infrared radiation it emits. Thermal devices are designed so that they convert the emitted radiation to stimuli that our eyes can detect. The sensors on night vision devices work in a similar way – the infrared light, invisible to the human’s naked eye, is converted to an image that we can see.
The measuring devices that capture the infrared radiation are called detectors – each pixel is equipped with it. Once the detector measures the temperature, the corresponding pixel is assigned a specific colour – the temperature pattern created is called a thermogram. The information, obtained almost in an instant, is then translated into electric impulses. These are sent to a unit that processes the signal (a circuit board) and translates the acquired information into data that can be shown on the display. On the display, the information is shown in various colours which mark the intensity of the infrared radiation emitted. The combination of the information acquired by all the detectors forms an image that we see on the display.
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