I think that Mike did an excellent job of going over the history of temperature sensors and how they work. When I was assigned this post, I immediately though of a thermistor, however it is important to think about the history of temperature sensor, and that the analog approach has worked very well for a long time. I personally got very interested while reading Elda's post when she talked about the use of infrared thermometers. Elda talks about how infrared thermometers are used to detect temperatures without the need for surface contact. This brought me to the idea to discuss thermography as a type of "temperature sensor."
A paper written by Maldague shows there are two main types of thermography, passive and active. These two types of thermography are discussed as a means of Non-Destructive Evaluation Techniques (NDT). The idea behind active thermography is to send a wave of energy (in the form of heat), and see how the heat moves in the observed medium. Passive thermography on the other hand uses energy already found in the observed medium such as the difference in temperature of a pipe or electric box that generates or takes heat to show how the materials around it act. Thermography can easily be used to determine if an electrical box is overheating and needs attention. It can also be used for firefighters to determine what is going on in a household in the event of a fire, and where people are located inside the burning structure.
The most basic description of thermography, is the use of an infrared camera to detect the radiation from a given material, that then is translated to a surface temperature. It is important (according to NDT sources) to know the emissivity of the material observed to get an accurate reading of what temperature is being observed. If the wrong emissivity is chosen, than the entire process of thermography can become a fruitless exercise.
One can see each different way of measuring temperature has its pros and cons, and there is no one solution fits all approach for measuring temperature.
A paper written by Maldague shows there are two main types of thermography, passive and active. These two types of thermography are discussed as a means of Non-Destructive Evaluation Techniques (NDT). The idea behind active thermography is to send a wave of energy (in the form of heat), and see how the heat moves in the observed medium. Passive thermography on the other hand uses energy already found in the observed medium such as the difference in temperature of a pipe or electric box that generates or takes heat to show how the materials around it act. Thermography can easily be used to determine if an electrical box is overheating and needs attention. It can also be used for firefighters to determine what is going on in a household in the event of a fire, and where people are located inside the burning structure.
The most basic description of thermography, is the use of an infrared camera to detect the radiation from a given material, that then is translated to a surface temperature. It is important (according to NDT sources) to know the emissivity of the material observed to get an accurate reading of what temperature is being observed. If the wrong emissivity is chosen, than the entire process of thermography can become a fruitless exercise.
One can see each different way of measuring temperature has its pros and cons, and there is no one solution fits all approach for measuring temperature.
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