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How do Infrared Thermometers Work?

How do Infrared Thermometers Work?

How do Infrared Thermometers Work?

To people who haven’t seen them before, infrared thermometers might look like something straight out of an episode of Dr Who. It’s no wonder some people are hesitant about the safety of using an IR thermometer. But infrared thermometers are far more hygienic than oral, axillary and rectal thermometers, and tend to be more accurate too, provided you use a CE Certified unit.

We’ll go through how infrared thermometers work in this article.


What is a laser thermometer?

Infrared Thermometer Definition:

A laser thermometer, also called a contactless thermometer, infrared thermometer, IR thermometer, or non-contact thermometer is just want its name suggests: a device for measuring temperature without the need for physical contact.

What do infrared thermometers measure?

A laser thermometer can be used to measure the temperatures of the following:

  • Humans when they are having a medical exam or going through an infection control protocol.
  • Animals if they need medical assessment or attention.
  • Food and beverages being cooked and served to people.
  • Surfaces.
  • Objects such as car engines, fridges, and circuit breakers.
  • Patches of a wall or floor, for example, to check insulation inside.

Infrared thermometers are useful for measuring the temperature in hard to reach places like air vents, or potentially dangerous places that could otherwise require someone to be in close proximity to a hazard, like an aggressive animal or an unstable electrical unit.


How do laser thermometers work?

To understand how an infrared thermometer works it’s important to first understand infrared radiation. With every laser thermometer, how it works depends on the infrared radiation available to measure and convert to temperature.

Infrared Radiation

All objects emit infrared radiation unless they have a temperature of absolute zero. When an object or organism is not at absolute zero its atoms will move about. The more movement that occurs in an object’s atoms, the higher temperature it will be. The energy emitted by the movement of the atoms is infrared radiation.

We can’t see infrared radiation with the naked eye, because its wavelengths are not on our visible spectrum, but we can feel it as heat. The sun is probably the largest source of infrared radiation we experience on earth, and it is also the strongest source of heat.

If something gets above a certain temperature it ‘jumps’ to the visible spectrum. A piece of red hot metal is an example of infrared heat jumping to the visible spectrum. This is caused by thermal vibrations being released as photons. Incandescent light is released at around 800°c, making the object literally glow with heat.

Learn more about the accuracy of contactless thermometers in our blog.


How do infrared forehead thermometers work?

It is this infrared energy that infrared thermometers measure to determine the temperature of an object. Infrared thermometers use a lens to focus IR energy being emitted by an object onto a detector called a thermopile inside the device.

So, how does an infrared thermometer measure temperature? The thermopile is responsible for converting IR energy into a temperature reading that we can understand. A thermopile is made up of thermocouples (two dissimilar wires that are connected to form a junction) which when warmed or cooled generate a voltage or electricity. The proportionate voltage output is used to determine temperature, which is then displayed on an LED screen on the device.

This process occurs in a matter of seconds or less. The Berrcom Non-Contact Thermometer has a read time of just one second, making it a good choice for busy environments like front of house in pubs, bars, and restaurants.

Infrared Thermometer Temperature Range

How a laser thermometer works is useful to know when you need to use one at work, but what temperature range can it be used at? The temperature range of an infrared thermometer will be different depending on what its primary use is. Catering thermometers will need to measure temperatures below -15°C and into the hundreds. Body temperature thermometers do not need to measure such a drastic range.

The Berrcom Non-Contact Thermometer has a temperature range of 32.0°C–43.0°C, offering significant buffer space on either end of the spectrum for human temperatures where life-threatening hyperthermia occurs at around 40°C and hypothermia begins to affect the brain at 33°C.

The accuracy of a contactless thermometer will also be affected by where a temperature sits in its readable range. This is why human thermometers are not suitable for animals and catering thermometers are not as accurate as with humans. 

The Berrcom Contactless Thermometer has a temperature reading accuracy of:

  • 32.0°C - 34.9°C: ±0.3°C
  • 35.0°C - 42.0°C: ±0.2°C
  • 42.1°C - 43.0°C: ±0.3°C

How do Infrared Thermometers Work?

In this video, we'll go through how infrared thermometers work.

Please enter your details into the form below along with any questions or comments and a member of our team will be happy to provide you with more information:


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