I use thermal camera very often at my job at the Petroleum Industry of Serbia. I use Fluke Ti55. This is excellent camera. Usually I have made thermal pictures of transformer stations, distribution boards, electric motors and pumps.
How thermal camera works?
Our eyes work by seeing contrast between objects that are illuminated by either the sun or another form of light. This is in the electromagnetic visible spectrum. In terms of frequency, this corresponds to a band in the vicinity of 430 – 770 THz.
Thermal cameras work is by “seeing” heat energy from objects. All matter with a temperature greater than absolute zero emits thermal radiation. Most of the thermal radiation emitted by objects near room temperature is infrared (300 GHz – 430 THz). Thermal camera creates images from infrared thermal radiation.
Emissivity is a term describing the efficiency with which a material radiates infrared energy. Real-world objects have emissivity values between 0 and 1.00. An emissivity of 0.90 implies that the material is 90% efficient at radiating energy. An emissivity of 0.40 implies that the material radiates only 40% of that which it is capable of radiating.
More about emissivity can be finds here: http://www.optotherm.com/emiss-table.htm
More about thermography will be in future posts.