Ir detectors
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This document discusses different types of infrared detectors, including thermal and quantum detectors. It provides details on thermal detectors such as thermocouples, bolometers, and pneumatic cells which detect infrared radiation by measuring the heating effect. Specifically, it describes how thermocouples generate a potential difference from heating a junction of dissimilar metals, and how pneumatic cells measure infrared intensity through the expansion of gas in a sealed chamber upon heating.
Ir detectors
- 1. IR DETECTORS SUBMITTED BY- MUHAMMED RAEES PC MUNAWAR CK NEDHEESH J BOSE
- 11. IR DETECTORS
- 12. TYPES OF IR DETECTORS • THERMAL – THERMOCOUPLE-THERMOPILE – BOLOMETER – PNEUMATIC CELL – PYROELECTRIC DETECTOR • QUANTUM – INTRINSIC • PHOTOCONDUCTIVE • PHOTO VOLTAIC – EXTRINSIC
- 13. THERMAL DETECTORS • DEPENDS ON HEATING EFFECT OF RADIATION
- 14. THERMOCOUPLE TYPE • MOST WIDE • SIGNAL ORIGINATES FROM A POTTENTIAL DIFFERENCE CAUSED BY HEATING A JUNCTION OF UNLIKE METALS • ONE JUNCTION BETWEEN THE TWO METALS IS HEATED BY IR BEAM • OTHER JUNCTION IS KEPT AT CONSTANT TEMP.
- 17. PNEUMATIC DETECTOR • GOLAY-1947 • MEASURES THE INTENSITY OF IR RADIATION BY FOLLOWING THE EXPANSION OF GAS UPON HEATING • GOLAY CELL-A CHAMBER CONTAING XENON-LOW THERMAL CONDUCTIVITY GAS • SEALED AT FRONT END BY BLACKENED RECIEVER • REAR WALL- FLEXIBLE MEMBRANE WITH A MIRRORED SURFACE • IR ENERGY FALLING ON RECIEVER WARMS UP GAS IN CHAMBER • RISE IN TEMP OF GAS IN CHAMBER – A DISTORTION OF MIRROR DIAPHRAGM-WHICH REFLECTS THE LIGHT TO S PHOTO CELL
- 19. REFERENCE • NPTEL >> Chemical Engineering >> Modern Instrumental Methods of Analysis (Video) >> Infrared Spectroscopy -1 • https://www.ee.iitb.ac.in/~esgroup/es_mtech 04_sem/es_sem04_paper_04307417.pdf