A basic infrared temperature sensor, also known as an infrared thermometer or IR thermometer, measures the temperature of an object without direct contact by detecting the infrared radiation emitted by the object. All objects with a temperature above absolute zero (-273.15°C or 0 Kelvin) emit infrared radiation in the form of heat. This phenomenon is described by Planck's law of black-body radiation.
Here's how a basic infrared temperature sensor works:
Infrared Sensor: The core component of the infrared thermometer is an infrared sensor or detector, which is sensitive to infrared radiation. The sensor is usually made of a material that can absorb infrared radiation and convert it into an electrical signal. One common type of infrared sensor used is a thermopile.
Optics: The infrared thermometer is equipped with optics to focus the infrared radiation from the object onto the infrared sensor. It may use lenses or mirrors to achieve this. The optics ensure that the sensor captures the radiation from a specific spot on the object being measured, usually the area in the center of the device's field of view.
Emissivity Adjustment: The emissivity of an object determines how efficiently it emits infrared radiation. It's important for accurate temperature measurements to consider the emissivity of the object. Emissivity can vary depending on the material and surface properties of the object. Some infrared thermometers allow users to adjust the emissivity setting based on the type of surface they are measuring (e.g., metal, wood, skin, etc.).
Reference Temperature: Some infrared thermometers may include a reference temperature sensor (usually a thermocouple) that measures the ambient temperature of the surrounding environment. This reference temperature is used to compensate for any differences between the ambient temperature and the temperature of the object being measured.
Conversion to Temperature: Once the infrared sensor detects the incoming radiation, it converts it into an electrical signal. This signal is then processed by the electronics within the thermometer to calculate the temperature of the object based on the intensity of the detected infrared radiation and taking into account the emissivity and ambient temperature compensation.
Display: The calculated temperature is displayed on the screen of the infrared thermometer for the user to read.
It's important to note that the accuracy of infrared thermometers can be influenced by factors like the distance between the sensor and the object, the presence of dust or other particles that might affect the optics, and the object's emissivity. For certain applications, more sophisticated infrared temperature sensors are used, such as those used in industrial settings, which can be more accurate and offer additional features.