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.

1. IR DETECTORS
SUBMITTED BY-
MUHAMMED RAEES PC
MUNAWAR CK
NEDHEESH J BOSE

2. Moon Mineralogy Mapper

3. Near-IR Spectrometer (SIR-2)

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