IR DETECTORS

SUBMITTED BY-MUHAMMED RAEES PCMUNAWAR CKNEDHEESH J BOSE

Moon Mineralogy Mapper

Near-IR Spectrometer (SIR-2)

IR DETECTORS

TYPES OF IR DETECTORS

• THERMAL– THERMOCOUPLE-THERMOPILE– BOLOMETER– PNEUMATIC CELL– PYROELECTRIC DETECTOR

• QUANTUM– INTRINSIC

• PHOTOCONDUCTIVE• PHOTO VOLTAIC

– EXTRINSIC

THERMAL DETECTORS

• DEPENDS ON HEATING EFFECT OF RADIATION

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.

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

REFERENCE

• NPTEL >> Chemical Engineering >> Modern Instrumental Methods of Analysis (Video) >> Infrared Spectroscopy -1

• https://www.ee.iitb.ac.in/~esgroup/es_mtech04_sem/es_sem04_paper_04307417.pdf