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thermal imaging imageWhat is a Thermal Imaging Camera?

Posted on: 24th, July 2015

A thermal imaging camera can also be referred to as an infrared camera or thermal imager. At their most basic level, they convert infrared energy into electrical signals that are displayed on a screen for trained human operators to interpret. In this blog we explore the basics.

thermal imaging image

A thermal imager is a powerful tool, allowing well-trained thermographers to measure temperatures without coming into physical contact with the target. However, the thermographer still must interpret the data being measured.

More advanced thermal imagers; those that measure temperature, are referred to as being ‘radiometric’. Unlike contact temperature measurement techniques, such as thermocouples or resistance temperature devices (RTD); using a thermal imaging camera to measure temperature is easier. As opposed to simply displaying a thermal image, it requires a complex set of algorithms and supplemental sensor inputs to achieve repeatable and accurate readings.

How does a thermal imaging camera work?

It would be simple to assume that a thermal imager operates in the same way as a digital camera, and that the rules which apply to digital imaging are translatable to infrared imaging. Whilst in some instances this is correct, there are key situations where a thermal imager operates in a distinctly different way to a digital camera.

The most important difference between the two camera types is what is placed between the camera and the object or heat source being observed, and how the camera responds to the interposing body. A digital camera operates in much the same wavelength as the human eye; in that exactly what a human sees, the camera does, too. A thermal imaging camera, on the other hand, operates in an infrared ‘band’. Typically, for today’s thermal imagers, this band is 8-14μm, also known as the long wave part of the infrared spectrum. This means that the thermal imaging camera is looking at a different section of the electromagnetic spectrum than the human eye and therefore the thermal camera distinguishes things an eyeball cannot. Heat is a good example of this, but the thermal imaging camera is also restricted by obstacles such as plastic or glass for example; whereas our eyes are not. A thermal imager cannot see through glass, most plastics, and many other materials; even if they are visually transparent.

Unlike a thermal imager, an infrared window is, for the most part, an inert device with an ‘optic’ manufactured from a material transparent in the infrared spectrum; or part of it at least. Infrared windows are permanently installed into electrical equipment cabinets allowing a thermographer to inspect the equipment’s interior without defeating safety interlocks, opening equipment doors and exposing themselves to energised points inside the equipment.

Unfortunately, all infrared window types are also not 100% transparent and therefore they act as a filter with respect to data observed by the thermal imager. Although the camera image displayed by a thermal imager may be clear, the measurement temperature values displayed will be incorrect.

The ultimate goal for any equipment user and thermographer is detecting the most accurate temperature measurement, in a cost effective manner. The CorDEX TC7150 NRTL listed infrared camera and the CorDEX TC700 ATEX and IECEX certified infrared camera will help you do this.

For more information on our range of thermal imaging cameras or any of our other intrinsically safe products, browse our website or contact one of our advisors on +44 (0) 1642 454373.

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