Thermal Imaging

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Thermal Imaging

Thermal Imaging is the conversion of radiated or reflected heat into real-time pictures or images. A thermal image is an analogue visual representation of temperature differences. All objects above absolute zero (-273 degrees) emit radiation waves that are infrared. Depending on temperature and emissivity, most objects in the world can be thermally imaged.

Thermal Imaging can be applied in many varying circumstances to simplify the detection, location and assessment of temperature related problems. Thermal imaging is used for a variety of heat detection tasks including checking for leaks (for all substances have slightly different temperatures) to surveillance/night vision (detecting body heat for when visual detection isn' t possible). Thermography is a science capable of providing very detailed images of situations invisible to the naked eye. Thermal infrared imagers are transverse wave detectors and lens combinations that give a visual representation of infrared energy.

The most common tool used for thermal imaging today is the thermal infrared camera. Thermal infrared cameras can be used to detect and display the presence of anything radiating heat above absolute zero. They supply visual representation of the infrared energy emitted by all objects. These cameras come in two types, those that take stills (like photos) and those that record motion imagery (like video). All imagers can only see through a limited density of material. For example if you took an image of a pipe at the right detection setting you would see the pipe and any leaks but you wouldn't see what was happening inside the pipe. Thermal imagers can passively see all objects regardless of ambient light. Video images, colour or black-and-white hard copy, or electronic data format can be captured for further manipulation.

The infrared spectrum

Thermal energy is transmitted in the infrared wavelength ( 1 micron to 100 microns ). You can see by the image above that thermal energy is closely related to visible light in that it travels in a wave. The human eye can only see the narrow middle band of visible light that encompasses all the colors of light in the rainbow. Thermal infrared imagers translate the energy transmitted in the infrared wavelength into data that can be processed into a visible light spectrum video display.

Heat transmission between objects

The first image displays two adults and a child through an infrared thermal imager. After a minute of sitting on the couch the thermal infrared energy of the people is transferred and stored in the couch until they get up.

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