Thermography is a technology that creates and analyzes images by detecting the heat radiating from an object. All objects, both animate and inanimate, emit varying degrees of heat that are not visible to the naked eye. By using infrared sensors, an image can be made that shows objects in the dark, or that shows areas of relative cool and warmth. A thermograph can be created without any physical contact with the object being analyzed, so thermography has military, medical and industrial applications.
How It Works
An infrared sensor picks up light from the infrared range of the electromagnetic spectrum. The infrared range is in a slightly lower frequency than the visible light spectrum that the human eye can see. As the temperature of an object increases, the amount of infrared radiation from its surface also increases. The infrared sensors used in thermography "see" this infrared radiation and create an image. Warm objects (or warmer parts of an object) stand out against cool backgrounds and vice versa. Thermographic images can be viewed in real-time, as with night-vision goggles, or they may be recorded on film for later analysis, as with the computerized thermal imaging used in the medical industry.
Night-Vision Goggles
One of the more well-known uses of thermography is night-vision goggles, which allow a user to see objects when it is completely dark. Humans and animals are warmer than the inanimate objects that surround them, so it is possible to see and track them using glasses with infrared sensors. Night-vision goggles are used by the military for surveillance at night or in closed places with no light, giving soldiers an advantage because it's possible to see another person without being seen by him or her. Night-vision goggles can also be used by animal researchers to gain information about an animal's nocturnal activities.
Swine Flu Screening
In 2009 amid swine flu fears, many airports installed thermal imaging cameras to screen incoming and outgoing passengers for infectious diseases. Because thermography is capable of detecting elevated body temperatures, passengers with fevers can be spotted without taking each person's temperature with a thermometer, allowing airport officials to quarantine passengers suspected of being ill.
Computer Thermal Imaging
Another medical application of thermography, called computerized thermal imagining (CTI), is currently (as of 2009) in clinical trials as a non-contact, less painful alternative to mammography for early breast cancer detection. Since tumors have a slightly higher temperature than normal tissue, CTI uses an infrared camera to take thermal photographs of the breast, which are digitally reconstructed to show if cancer is present.
Industrial Uses
Thermography has a wide range of industrial uses. For example, it can be used to troubleshoot electric connections and find hot spots or short circuits, it can detect heat and moisture loss in buildings and HVAC systems, it can be used to spot leaks in machine insulation systems and it can be used to monitor possible overheating in engines or other machine parts. Thermography is safe to use because surfaces can be tested and monitored without a person coming into contact with dangerous chemicals or hot machines and materials.
Tags: infrared sensors, computerized thermal, contact with, infrared radiation, infrared range
