[justify]Thermography is a non-contact, non-destructive test method that utilizes a thermal imager to detect, display and record thermal patterns and temperatures across the surface of an object. Infrared thermography may be applied to any situation where knowledge of thermal profiles and temperatures will provide meaningful data about a system, object or process.
Since infrared radiation is emitted by all objects based on their temperatures, according to the black body radiation law, thermography makes it possible to "see" one's environment with or without visible illumination. The amount of radiation emitted by an object increases with temperature; therefore thermography allows one to see variations in temperature.
Thermography is widely used in industry for predictive maintenance, condition assessment, quality assurance, and forensic investigations of electrical, mechanical and structural systems. Other applications include, but are not limited to: law enforcement, firefighting, search and rescue, and medical and veterinary sciences.
Recent History of Thermography
The major advances of the last 30 years have been with infrared thermal imaging. The surface of the human body is a highly efficient radiator and it is possible to detect the infrared emission from the skin, and create a thermal map of temperature distribution by remote sensing.The astronomer, Sir William Herschel, in Bath, England, discovered the existence of infrared radiation by trying to measure the heat of the separate colors of the rainbow spectrum cast on a table in a darkened room. He found the highest temperature to fall beyond the red end, which he reported to the Royal Society as Dark Heat in 1800. His son, Sir John Herschel, who was more interested in photography, managed to record the heating rays on the infra red side of red by creating an evaporograph image using carbon suspension in alcohol. He termed this image a thermogram. The foundation was laid for the advances that would come over a century later with the sophisticated thermal imaging devices that are used in military, industrial and medical applications.
1990 – Honeywell Research develops the microbolometer. Mid 1990’s Rockwell, Boeing and Lockheed build the 1st microbolometer based imaging systems for military applications. In August of 1997, after 4 to 5 years of development Agema Infrared introduces the 1st hand held imaging radiometer. This 570 system sold for $49,950.00 and a software package was $6995.00, bringing the total average sale price of a system to almost $57,000.00 USD. I know this because I was one of the guys I the field selling these systems.
In mid 1998, the Thermovision fixed camera system is developed and costs around $40,000.00 and is sold with software for about $47,000.00. It took Agema about six months to get the 570 handheld systems solid and stable, just as many new products today. The first hand held imagers were much noisier in terms of image quality and definitely in comparison with their PTSI, stirling cooled predecessors.
3. What makes Thermography useful?
1. It is non-contact
-Uses remote sensing
-Keeps the user out of danger
-Does not intrude upon or affect the target at all
2. It is two dimensional
-Comparison between areas of the target is possible
-The image allows for excellent overview of the target
-Thermal patterns can be visualized for analysis
3. It is real time
-Enables very fast scanning of stationary targets
-Enables capture of fast moving targets
-Enables capture of fast changing thermal patterns
Fact…Temperature is the number one form of measurement used in any process control application. As we get better at non-contact measurement and customers gain confidence, the technology will expand. Pressure and flow are also critical measurements as well, but temperature is far and away number one.[/justify]