Thermography.ppt
- 1. THERMOGRAPHYBY :SOHIT KUMAR CHAUHAN
- 3. MID INFRARED
- 4. THERMAL INFRAREDATOMSTWO ENERGY ORBITALS
- 7. ELECTRON MOVES TO HIGHER ORBIT
- 8. WHEN COMES BACK RELEASES ENERGY AS PHOTONTHERMAL ENERGYThermal images, or Thermograms, are actually visual displays of the amount of infrared energy emitted, transmitted, and reflected by an object.
- 9. Incident Energy = Emitted Energy + Transmitted Energy + Reflected Energy
- 10. Second law of thermodynamics and EmissivityRADIATIVE HEAT EXCHANGE
- 11. EMISSIVITYEmissivity is a term representing a material's ability to emit thermal radiation
- 12. THERMAL IMAGING SYSTEM
- 15. Planck's Equation shows, the peak energy shifts towards shorter wavelengths as the temperature increases.
- 16. TWO COLOR THERMOMETRY
- 17. TYPES OF INFRARED DETECTORSUNCOOLED INFRARED DETECTORUse a sensor operating at ambient temperature.
- 18. Cooling is not necessary.
- 19. Use sensors that work by the change of resistance, voltage or current when heated by infrared radiation.COOLED INFRARED DETECTORUse sensors with operating range from 4k to just below room temperature.
- 20. The cooling is necessary for the operation of the semiconductor materials used.
- 21. Use sensors that work by catching IR radiations.UNCOOLED INFRARED DETECTORCOOLED INFRARED DETECTORDo not require bulky, expensive cryogenic coolers
- 22. They are smaller and less costly.
- 23. Materials used for uncooled infrared detection are vanadium(V) oxidelanthanum barium manganiteamorphous siliconlead zirconate titanate(PZT)Lanthanum doped lead zirconate titanateRequire cryogenic coolers for cooling.
- 24. They are expensive both to produce and to run.
- 25. Materials used for cooled infrared detection are indium antimonideindium arsenidemercury cadmium telluridelead sulfidelead selenide
- 26. ADVANTAGESIt shows a visual picture
- 27. It is capable of catching moving targets in real time
- 28. It is able to find deteriorating
- 29. It can be used to measure or observe in areas inaccessible or hazardous for other methods
- 30. It is a non-destructive test method
- 31. It can be used to find defects
- 32. It can be used to detect objects in dark areasDISADVANTAGEShigh price range
- 33. Images can be difficult to interpret accurately when based upon certain objects
- 34. Accurate temperature measurements are hindered by differing emissivities and reflections from other surfaces
- 35. Most cameras have ±2% accuracy or worse
- 36. Only able to directly detect surface temperaturesAPPLICATIONSCondition monitoring
- 37. Digital infrared thermal imaging in health care
- 38. Thermology
- 40. Night vision
- 41. Research
- 42. Process control
- 44. Surveillance in security, law enforcement and defence
- 45. Chemical imaging
- 46. Volcanology
- 48. In health care
- 51. Defence
- 53. REFERENCESRogalski A. and Chrzanowski K. 2002, “Infrared Devices and Techniques”, Contributed Paper: Opto-electronics Review
- 54. Darling, Charles R.; "Pyrometry. A Practical Treatise on the Measurement of High Temperatures." Published by E.&F.N. Spon Ltd. London. 1911