IR THERMOMETERS
A Thermometer is a device that measures temperature or temperature gradient. It has two important elements, a temperature sensor (like the bulb of mercury-in-glass thermometer) in which changes occur with a change in temperature, and some means (say marked visible scale) that convert this change into a numerical value.
It is a product which is now seen having an important role and demand due to the ongoing COVID-19 pandemic. The frequently used Mercury Thermometer must be in contact with the human body in order to measure the body temperature. Owing to those limitations, the new IR Thermometer became more popular, which is of non-contact type, providing a faster response than traditional mercury thermometer.
IR Thermometer infers temperature from a portion of thermal radiation called Black Body radiation. They are often called laser thermometers due the use of lasers to measure temperature from a distance. By knowing the amount of infrared energy emitted by the object and its emissivity, the object’s temperature can be determined within a certain range of its actual temperature. Infrared thermometers are a subset of devices known as ‘thermal radiation thermometers’. Sometimes, especially near ambient temperatures, readings may be subject to error due to the reflection of radiation from a hotter body, including the person holding the instrument rather than radiated by the object being measured, and can lead to an incorrectly assumed emissivity.
IR thermometers mainly work on the principle of black body radiation. Like visible light, infrared can be focused, reflected and absorbed. Handheld IR thermometers use lenses for focusing the infrared energy from the object to the sensor that measures it, typically a thermopile. The sensor absorbs radiation and converts it to an electrical signal, with more intense radiation creating a stronger signal. The IR thermometers process this signal in order to deliver temperature readout. The higher the temperature, the faster the molecules move.
The molecules emit infrared radiation as they move, and emit more radiation, including visible light, as they get hotter. This is why a heated metal emits a red or white glow. Infrared thermometers detect and measure this radiation. Infrared light can be focused, reflected or absorbed like visible light. IR thermometers employ a lens to focus infrared light from an object onto a detector known as a thermopile. The function of the thermopile is to absorb infrared radiation and convert it to heat. The thermopile gets hotter as it absorbs more and more infrared energy. The excess heat is converted into electricity, which is transmitted to a detector which determines the temperature of the object.
IR is a type of radiation emitted from all bodies and is a part of the electromagnetic spectrum. This works in tandem with what is known as emissivity or the measure of efficiency in which the surface emits thermal energy.
Non-contact IR thermometers are designed for body surface temperature measurement for adults and infants without contact with the human body. Non-contact IR thermometers can also be used to measure the temperature of a hot body or room by using the surface temperature function.
While selecting thermometers, we consider the following factors:-
- Accuracy- It depends on distance-to-spot ratio. This ratio indicates the maximum distance from where a thermometer can evaluate a specific surface area. Bigger the ratio, farther the distance the temperature can be measured from.
- Emissivity- It shows how much infrared energy a thermometer can put out on a time.IR thermometers with emissivity closer to 1.00 can read more materials than the ones with lower emissivity.
- Temperature range- A wide temperature range should be selected to record various processes with different temperatures.
- Reading speed or response time- Time taken to deliver accurate reading
As the world comes to terms with the COVID-19 pandemic caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-Cov-2), many innovations have helped us cope up with this pandemic. Fever being a major symptom, IR thermometers play a major role due to its quick measurement and accuracy. When compared to the other thermometers in the market, regardless of its price, the IR thermometer has made a major significance in the midst of a pandemic.
