A basic infrared temperature sensor, also known as an infrared thermometer or pyrometer, measures surface temperature by detecting the thermal radiation emitted by the object being measured. Here's a simplified explanation of how it works:
Thermal Radiation Emission: All objects with a temperature above absolute zero emit thermal radiation in the form of infrared light. This radiation is related to the object's temperature and is governed by the Stefan-Boltzmann law. Hotter objects emit more intense radiation.
Infrared Sensor: The infrared temperature sensor includes a lens that focuses the emitted infrared radiation onto a detector element. This detector element is often made of materials like thermopiles or microelectromechanical systems (MEMS) that are sensitive to infrared radiation.
Detection: When the focused infrared radiation hits the detector element, it absorbs the radiation and generates a small electrical signal. The strength of this signal is proportional to the intensity of the incoming radiation, which in turn is related to the temperature of the object emitting the radiation.
Conversion: The electrical signal is then converted into a temperature reading using calibration factors and algorithms. The sensor incorporates a temperature-to-voltage or temperature-to-resistance converter, which helps translate the electrical signal into a temperature value.
Display or Output: The converted temperature value can be displayed on the sensor itself using a digital or analog readout. It can also be sent to other devices, such as microcontrollers, computers, or displays, for further processing or recording.
Emissivity Correction: Many objects don't emit radiation uniformly, and their surface characteristics can affect the accuracy of the temperature measurement. The emissivity of an object, which indicates how efficiently it emits radiation compared to a perfect emitter (a blackbody), needs to be considered. Some sensors allow you to adjust the emissivity setting to compensate for this variation.
Distance Consideration: Infrared temperature sensors measure an average temperature across the field of view. Therefore, the distance between the sensor and the object being measured can affect the accuracy of the measurement. Some sensors have adjustable focus or optics to account for different distances.
It's important to note that while basic infrared temperature sensors are effective for non-contact temperature measurements, they might have limitations in terms of accuracy, distance, and environmental conditions. More advanced sensors with additional features can overcome some of these limitations, but the basic principle of measuring the emitted thermal radiation remains the same.