A basic infrared temperature sensor, often referred to as an infrared thermometer or IR temperature sensor, measures the temperature of an object by detecting the infrared radiation emitted by the object. This process relies on the principles of blackbody radiation and the Stefan-Boltzmann law.
Here's a simplified explanation of how it works:
Infrared Radiation Emission: All objects with a temperature above absolute zero (-273.15°C or 0 Kelvin) emit infrared radiation as a result of their thermal energy. The amount and wavelength of this radiation depend on the temperature of the object. Warmer objects emit more radiation, and the distribution of emitted radiation shifts towards shorter wavelengths as the temperature increases.
Infrared Sensor: The infrared temperature sensor consists of a lens, an infrared detector, and an electronic circuit. The lens focuses the infrared radiation from the object onto the detector.
Detection: The infrared detector is typically made of materials sensitive to infrared radiation, such as thermopiles or microbolometers. These materials absorb the incoming infrared radiation and convert it into a change in electrical resistance or voltage.
Temperature Calculation: The electronic circuit in the sensor processes the electrical signals from the detector. The amount of infrared radiation detected is proportional to the temperature of the object. By using a calibration curve that relates the detected radiation to known temperatures, the sensor can convert the detected signal into an approximate temperature reading.
Emissivity Compensation: Emissivity is the measure of how efficiently an object emits thermal radiation. Different materials have different emissivity values. To get accurate temperature readings, the sensor often has an adjustable emissivity setting that allows the user to account for the emissivity of the object being measured. Some sensors also have a fixed emissivity value, which works well for certain common materials.
Display or Output: The sensor may have a built-in display that shows the temperature reading directly. In industrial settings, these sensors can be connected to data acquisition systems or controllers to integrate temperature measurements into automated processes.
It's important to note that while basic infrared temperature sensors are quite useful for non-contact temperature measurements, they have limitations. They typically work well for a wide range of temperatures but may not be as accurate as contact-based methods like thermocouples or RTDs in certain high-precision applications. Additionally, factors such as the distance between the sensor and the object, as well as the presence of surrounding heat sources, can influence the accuracy of measurements.