What is a thermal imaging camera? Thermal cameras or thermal imagers are devices that translate thermal energy (heat) into visible light (color) in order to analyze a particular object or scene. thermal imaging camera The image produced by thermal imaging cameras is known as a thermogram and is analyzed through a process called thermography.
How do they work? Nearly all objects radiate thermal energy from their surface. Modern thermal imagers use a detector called a microbolometer to sense this thermal energy. Microbolometers are composed of an array of pixels which are made of a variety of different materials most commonly, amorphous silicone and vanadium oxide. When thermal energy given off by an object strikes the pixel material, the material is heated changing its electrical resistance. This resistance can then be measured and translated into a temperature value. A thermogram is then produced by assigning colors or shades to each of these temperature values.
What do I look for when purchasing a thermal camera? There are numerous components that contribute to both the quality and the cost of a thermal imager. The two most important factors are the detector resolution and the thermal sensitivity.
The detector resolution describes the number of pixels in the microbolometer array. The most common resolutions of detectors are 160X120, 320X240, and 640X480 pixels. These values represent the number of horizontal pixels times the number of vertical pixels in the array. A 320X240 detector produces an image composed of 76,800 pixels. Since each pixel has a temperature associated with it, that is also 76,800 temperature data points. Higher resolutions also produce visibly clearer images (similar to digital cameras).
Thermal sensitivity is the smallest temperature difference the camera can detect. A sensitivity of 0.05°C means the camera can distinguish two surfaces with only a five hundredths of a degree temperature difference.
What features can I expect to find on a thermal imager? All of the portable imagers we carry capture images onto an included memory card which can then be transferred to a PC via USB interface. Each imager includes software that allows the user to analyze the images and create a report. As with most electronic devices, there are certain features or “selling points” that may make one imager more attractive to a potential user than another. Our thermal imaging comparison chart highlights these differences (link here). Here are a few to look for:
Built-in digital camera Field of view and the ability to add lenses (telephoto, wide, closeup) Video output to another device such as a computer, TV, or projector. Imager LCD display size Refresh rate (how fast the image updates, 60Hz = 60 refreshes per second) Touch screen capability Ability to focus lens automatically or manually Ability to add voice/text annotation Rugged, ergonomic design Who makes thermal imagers and infrared cameras? We carry three major manufacturers of thermal imagers and infrared cameras: Flir, Fluke, and Testo. Each manufacturer offers different design and functionality to best suit your application.
Flir has been in the thermal imaging business for over 30 years. For the first twenty years, their cameras were used primarily in government and military applications including aircraft, marine, and law enforcement. Since the cost of manufacturing has fallen over the past few years, Flir has been able to offer cameras for a wide range of applications at a variety of different price points.
Fluke has been designing and manufacturing test and measurement instrumentation since 1948. Fluke is known for their reliability and rugged design, intended for the toughest of industrial applications. All of Fluke’s thermal imagers are manufactured in the United States.
Testo has a very strong presence in the HVAC market especially with combustion analyzers, anemometers, and moisture products. Their imagers offer terrific value as well as strong performance in a variety of different applications.
How can I use my thermal imager? Now that you have a brief understanding how thermal imaging cameras work and what to look for, let’s discuss some common applications.