THERMOGRAPHY

THE BASICS NEAR INFRARED MID INFRARED THERMAL INFRARED

ATOMS TWO ENERGY ORBITALS LOW ENERGY ORBITAL HIGH ENERGY ORBITAL ELECTRON MOVES TO HIGHER ORBIT WHEN COMES BACK RELEASES ENERGY AS PHOTON

THERMAL ENERGY Thermal images, or Thermograms, are actually visual displays of the amount of infrared energy emitted, transmitted, and reflected by an object. Incident Energy = Emitted Energy + Transmitted Energy + Reflected Energy Second law of thermodynamics and Emissivity

RADIATIVE HEAT EXCHANGE

EMISSIVITY Emissivity is a term representing a material's ability to emit thermal radiation

THERMAL IMAGING SYSTEM

INFRARED TEMPERATURE MEASUREMENT

MODERN INFRARED THERMOMETER

Planck's Equation shows, the peak energy shifts towards shorter wavelengths as the temperature increases.

TWO COLOR THERMOMETRY

TYPES OF INFRARED DETECTORS UNCOOLED INFRARED DETECTOR COOLED INFRARED DETECTOR Use a sensor operating at ambient temperature. Cooling is not necessary. Use sensors that work by the change of resistance, voltage or current when heated by infrared radiation. Use sensors with operating range from 4k to just below room temperature. The cooling is necessary for the operation of the semiconductor materials used. Use sensors that work by catching IR radiations.

Require cryogenic coolers for cooling. UNCOOLED INFRARED DETECTOR COOLED INFRARED DETECTOR Do not require bulky, expensive cryogenic coolers They are smaller and less costly. Materials used for uncooled infrared detection are vanadium(V) oxide lanthanum barium manganite amorphous silicon lead zirconate titanate(PZT) Lanthanum doped lead zirconate titanate Require cryogenic coolers for cooling. They are expensive both to produce and to run. Materials used for cooled infrared detection are indium antimonide indium arsenide mercury cadmium telluride lead sulfide lead selenide

ADVANTAGES It shows a visual picture It is capable of catching moving targets in real time It is able to find deteriorating It can be used to measure or observe in areas inaccessible or hazardous for other methods It is a non-destructive test method It can be used to find defects It can be used to detect objects in dark areas

DISADVANTAGES high price range Images can be difficult to interpret accurately when based upon certain objects Accurate temperature measurements are hindered by differing emissivities and reflections from other surfaces Most cameras have ±2% accuracy or worse Only able to directly detect surface temperatures

APPLICATIONS Condition monitoring Digital infrared thermal imaging in health care Thermology Veterinary Thermal Imaging Night vision Research Process control Nondestructive testing Surveillance in security, law enforcement and defence Chemical imaging Volcanology Building

Condition monitoring

In health care

Process control Steel Ladle Manufacturing

Veterinary Thermal Imaging

Defence

Surveillance in security

REFERENCES Rogalski A. and Chrzanowski K. 2002, “Infrared Devices and Techniques”, Contributed Paper: Opto-electronics Review Darling, Charles R.; "Pyrometry. A Practical Treatise on the Measurement of High Temperatures." Published by E.&F.N. Spon Ltd. London. 1911 www.wikipedia. org www.howstuffworks.com

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