Ear thermometer for checking fever

How Does an Infrared Thermometer Work? 

Ear thermometer for checking feverInfrared or IR thermometers are among the top choices to measure temperature both in industrial and clinical environments. These temperature measurement devices, while considered non-contact, are as accurate as traditional thermometers. Moreover, IR thermometers function well in areas that other thermometers cannot reach or are not practical.

IR thermometers come in different types; one of the most commonly used is the infrared forehead thermometer. It looks like a tiny gun and requires to be pointed on the forehead for temperature reading. However, this type of IR thermometer requires near contact with the person to be checked.

Body temperature screening kiosks are now becoming more popular. It is now normally used at every establishment’s entrance. It is easy to use and does not require human assistance. Just stand in front of it, and it can read your temperature.

Infrared thermometers use the concept of infrared radiation to get any surface temperature without physical contact. It is now commonly used in all establishments as the first line of defense to pandemic COVID-19.

Infrared radiation 

Each object has atoms moving in it; no object has a zero temperature. The speed of the atoms’ movements affects the object’s temperature. The faster they move, the higher temperature they produce. The moving molecules release energy, forming infrared radiation.

Your naked eyes cannot see this radiation as its wavelength is longer than the visible light is producing. But the radiation can become visible if the object becomes too hot. An excellent example of this is a red-hot glowing metal.

While infrared radiation is not visible, it can be sensed in the form of heat. The best examples for this are the heat that we feel from sunlight, fire, or radiator. This is the heat that the IR thermometers are detecting to read your body’s and other object’s temperature.

Infrared thermometers 

Like the visible light, infrared light can also be focused, absorbed, or reflected. Infrared thermometers utilize a lens to direct the infrared light that is being released from the object onto the detector called the thermopile.

Thermopile is the thermocouples that are connected in a series of parallels. When the infrared radiation reaches the surface of the thermopile, it, then, will get absorbed and converted into heat. Gradually, it produces a voltage output that is equal to the incident infrared energy, and the detector uses this output to read the temperature, which will show up on the screen.

The whole process may sound complicated. However, this process takes only a few seconds for the IR thermometer to read the temperature and display it on the unit.

This is how an infrared thermometer works. So, how do you choose a good IR thermometer?

Temperature range 

The range of the infrared thermometer affects your work if you are going to use it. It is good to choose an infrared thermometer that offers a more comprehensive temperature range to record multiple processes with different temperatures.

On the other hand, an IR thermometer with a narrower temperature range performs better when you need higher resolutions. This ensures the correct temperature control of a certain process.


Accuracy is the most vital aspect of any thermometer. The accuracy of an IR thermometer relies on its D/S ratio (distance-to-spot ratio). The rate tells the max distance where the thermometer can read the temperature of a particular area.

For instance, you have an infrared thermometer with a D/S ratio of 8:1; it can detect temperature from a max distance of 32 inches (8:1 x 4). Thermometers with more significant ratios can see temperature from a farther distance. However, the area it covers widens as the distance increase.

Response or reading time 

The time an infrared thermometer needs to get you an accurate reading after its process is called the response or reading time. This aspect is crucial if you need to read the temperature of a moving object or objects that quickly heats up.


The amount of energy a thermometer can produce at a time is called emissivity. IR thermometers that are nearly around 1.00 emission level can read and measure more materials compared to thermometers with reduced emissivity value.

You may choose a thermometer with an adjustable emissivity level so that you can adjust the amount of infrared energy emitted. This will then compensate for the energy returned by the material that needs the temperature to be read.

There are other features that you may consider when buying an IR thermometer, but the ones that are mentioned above are essential. This is especially true if you are purchasing a body temperature screening kiosk.

So, this is how the IR thermometer works and if you need one, make sure to visit a reputable store that can give you quality products. Moreover, these thermometers are fragile, so make sure that it comes with a warranty.