A basic infrared temperature sensor, also known as an infrared thermometer or pyrometer, measures surface temperature by detecting the infrared radiation emitted by the object being measured. All objects with a temperature above absolute zero (-273.15°C or -459.67°F) emit infrared radiation in the form of electromagnetic waves. This radiation is directly proportional to the temperature of the object, following the principles of blackbody radiation.
Here's how a basic infrared temperature sensor works:
Infrared Detection: The sensor contains an infrared detector, which is usually made of a thermopile or a semiconductor material like thermopiles, thermocouples, or bolometers. These materials generate a small electric current when exposed to infrared radiation.
Optical System: The sensor has an optical system that focuses the infrared radiation from the object onto the infrared detector. This system may include a lens or a mirror to help focus the radiation onto the detector element.
Measurement: When you point the sensor at an object and pull the trigger (for handheld devices), the sensor detects the incoming infrared radiation. The amount of radiation reaching the detector is directly related to the temperature of the object. The detector converts the incoming radiation into an electrical signal.
Signal Processing: The electrical signal generated by the detector is very small and needs to be amplified and processed to provide a meaningful temperature reading. Signal conditioning and amplification circuits in the sensor convert the weak electrical signal into a measurable voltage.
Calibration: Infrared temperature sensors need to be calibrated to provide accurate temperature readings. This involves comparing the sensor's response to the radiation from objects of known temperatures. Calibration compensates for factors like sensor drift, emissivity (how well the object emits infrared radiation), and environmental conditions.
Display/Output: The sensor's output can be displayed on a screen or provided as an electronic signal for further processing. Handheld infrared thermometers often display the temperature directly on their screens. In industrial applications, the output might be integrated into a control system for automated temperature monitoring.
It's important to note that infrared thermometers are most accurate when measuring the temperature of objects that are relatively close to the sensor and fill a significant portion of the sensor's field of view. Additionally, the sensor's accuracy can be affected by factors such as the target's emissivity, distance, and environmental conditions (such as dust, humidity, or smoke) that can influence the emitted and received radiation.