How does Infrared Thermometers Work? : Application Advantages

What are Infrared Thermometers?

Infrared (IR) thermometers or contactless/non-contact thermometers can measure surface or body temperature from a distance using infrared radiations.

The use of non-contact IR thermometers to measure body temperature has increased drastically due to current Covid conditions. In this article, we will discuss in detail the infrared thermometerClick this link to know the various types of temperature sensors and their applications.

How Infrared Thermometers Work?

An Infrared thermometer works or measures a body/surface temperature by detecting infrared radiations coming from that body or surface.

Therefore to understand the working of an infrared thermometer, we need to understand what infrared radiations are? 

What are Infrared Radiations?

Infrared radiation is a type of electromagnetic radiation or heat due to the temperature difference between a body or surface and the atmosphere.

All hot bodies emit IR radiations that can even travel in a vacuum. The amount of IR radiation emitted by a body depends on its temperature and emissivity. Here emissivity is a material property that measures a body efficiency to emit thermal radiations.

Only a part of IR radiation is visible to human eyes because the light in IR -radiation wavelength (700 nm to 1 mm) range is not visible to humans.  Click here to know in detail about emissivity and the black body concept.

Working of Infrared Thermometer

As shown in the below image, IR Thermometers works and measure a body or surface temperature in the following four steps:

Step-1: Focus the energy coming from a body or surface in the form of infrared rays on a sensor known as a thermopile.

Step-2: Thermopile absorbs IR radiations in heat form and converts them into a voltage output. The output is in the range of tens or hundreds of millivolts.

Step-3: This output voltage is sent to the processor to calculate the temperature.

Step-4: Processor analyses the output and map its value with stored values to calculate the temperature. Afterward, the display shows the measured temperature.

This image shows the Working of Infrared Thermometer
Working of Infrared Thermometer

IR thermometers compare the IR radiations emitted by the object and a reference point to determine a body temperature. It ensures environmental temperature has a minimal impact on thermometer reading.

Applications of Infrared Thermometer?

IR thermometers have the following applications in healthcare and engineering fields.

  • Infrared thermometers are an alternative to temperature probe.
  • Check body temperature.
  • Check food or drink temperature during cooking or serving.
  • During product validation, engineers use an IR thermometer to check product temperature.
  • Check goods temperature during transportation.
  • Various agencies are using IR thermometers to monitor body temperature and control the spread of covid-19.

Advantages and Disadvantages of IR Thermometer?

Compared to traditional probe type or mercury thermometers, infrared thermometers has the following advantages:

  • IR Thermometers are very fast. Depending on thermometer quality. You can get reading even in less than 1 second.
  • Contactless temperature measurements are possible.
  • Digital IR thermometers come with memory options as well.
  • Easy to use.

Compared to traditional probe type or mercury thermometers, infrared thermometers has the following disadvantages:

  • IR Thermometers are more costly compared to conventional thermometers.
  • For a low-cost Infrared thermometer, temperature measurement accuracy is a concern.
  • IR thermometers requires a clean environment for temperature measurements.
Frequently asked questions: FAQ

It depends on the quality of the thermometer. Clinical grade infrared thermometers are available in an accuracy range of ±0.3º. ASTM E 1965-98 has defined the Standard Specification for Infrared Thermometers for intermittent determination of patient temperature.

Yes, We can use IR thermometers to measure a surface or skin temperature. But thermometers designed to measure a surface or body temperature can not be used to measure skin temperature.

In other words, to measure skin temperature accurately, you require FDA-approved IR thermometers for medical use.

Infrared thermometers don’t emit any radiation to measure temperature. They are sensing devices. For more safety

  • You can turn off the laser attached to the thermometer.
  • Use only clinically approved thermometers
  • Follow best practices for temperature measurement.

For more details, contact your doctor.

To sum up, Infrared thermometers are one of the best ways for contactless temperature measurement. It is also available at reasonable prices. 

We will keep updating this article on how infrared thermometers work. Write your suggestions and questions on the Working of Infrared Thermometers in the comment box.

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