What is a thermal imaging camera?

A thermal imaging camera is a camera that converts a part of the infrared light of the electromagnetic spectrum (EMS) into an image or video. A human being looks in the visual part of the EMS between 380nm and 780nm. But thermal imaging cameras are primarily built to view the IR spectrum from 780nm – 14000nm. You could divide the systems into 2 major groups. Namely the measuring instruments and the surveillance cameras.

In the market you will come across several synonyms for the word “thermal imaging camera”. Some examples include: thermal camera, infrared camera, IR camera, thermographic camera, thermocamera, … All these descriptions reflect what the thermal imaging camera does, namely, give us insight into how the heat is distributed over a given area or surface.

There are therefore many different types of cameras, just as there are for visual cameras. There are fixed setups for continuous monitoring, but there are also portable systems that can be taken into the field on a battery. To understand exactly what a thermal imaging camera does, it is important to properly define the terms ‘heat’ and ‘infrared light’.

Thus, a thermal imaging camera is capable of converting an amount of infrared light into a thermal image. This image contains the ratio of thermal radiation from different objects and allows us to analyze the status of these objects and how they behave in relation to each other. The science for analyzing these thermal images is called thermography.

How does a thermal imaging camera work?

How a thermal imaging camera works

A thermal imager receives IR radiation in a certain wavelength. This radiation is optimized and transmitted through a lens to the detector. This in turn transmits the information to the electronics that convert the image to a screen or viewfinder with or without the help of an additional computer.

Taking a visual picture therefore requires a different sensor that is sensitive to visual light. This is why many thermal imaging cameras are equipped with both a visual camera and a thermal sensor. Some properties of light are the same for a visual camera as for an IR camera. But there are also certainly many differences.
It is up to the thermographer to interpret these images correctly, taking into account the spectral properties of the IR spectrum, the capabilities of the camera, and the environmental factors.

More information on the IR spectrum, and on the entire electromagnetic spectrum (EMS) can be found in our article ‘What is Infrared Light?’

The impact of the thermographer

Although a thermal imager is often used to measure temperatures, it is not always the most accurate tool.
The thermographer has a huge impact on how well the thermal measurement is performed by setting radiation parameters such as emission, reflection and transmission. For this, it is recommended to take courses and/or verify that the thermographer is competent in their field. The knowledge required to analyze thermographic images is vastly underestimated. This also applies to other measuring instruments. However, because the camera immediately provides an image with a temperature, it is often considered a simple measurement tool.

Applications of a thermal imaging camera

Nevertheless, the thermal imaging camera is the most suitable measuring instrument for depicting the ratio of heat.
As a result, thermal imagers can be used on an infinite number of applications.

The most common applications are building thermography and measuring electrical panels. But the list of possibilities is endless. A small selection of the possible sectors in which thermal imaging cameras have already proven their usefulness are: preventive maintenance in industry, gas visualization/Optical Gas Imaging (OGI), medical sector, automotive industry, surveillance, chemical and petrochemical sector, food industry, electronics and consumer goods, science and research, aerospace, research on plants and animals, …

Important aspects to evaluate

Because of the wide range of possibilities, it is important that you let yourself be guided by the right people with knowledge and experience to have a thermographic investigation performed, or before purchasing a thermal camera.

There are distinctions between the quality and usefulness of thermal imaging cameras in several areas. The most important we can assign to following aspects:

  • Resolution and spatial resolution
  • Properties of the spectral range of the camera
  • The speed of measurement / measurement frequencies vs. image frequency
  • The possibility of synchronizing a thermal camera or not
  • The sensitivity of the sensor
  • A portable camera vs a fixed setup
  • The way to save images and analyze them afterwards in software
  • The ease of use of the thermal imaging camera

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