Post on 17-Jul-2015
INFRARED IMAGING
By
Sonawane Swapnil R
Sub.: CV
Department of Electronics & Telecommunication
VIIT, Pune
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OUTLINE
Infrared light
Emissivity
Infrared Thermography
Principle
Image format
Image camera
Advantages
Disadvantages
Applications
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INFRARED LIGHT
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Sir William Herschel
EMISSIVITY
a = absorption
t = transmission
r = reflection
For a blackbody, absorptivity=emissivity=1
Practically, absorptivity + transmissivity + reflectivity = 14
PLANCK’S LAW
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INFRARED THERMOGRAPHY
Detect the infrared energy emitted from object and
produce images of that radiation, called
thermograms.
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PRINCIPLE
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IMAGE FORMAT
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INFRARED CAMERA
Infrared cameras operate in wavelengths as long as
14,000 nm (14 µm)
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INFRARED CAMERAS...
Two types having:
Cooled Infrared detectors
Uncooled Infrared detectors
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Cooled Detector Uncooled detector
1. Use sensors with
operating range from 4K
to just below room
temperature
Use a sensor operating at
ambient temperature
2. Cooling is necessary for
operation of
semiconductor materials
used
Cooling is not necessary.
3. Use sensors that work by
catching IR radiations
Use sensors that work by
change of resistance,
voltage or current when
heated by infrared
radiation
4. Require cryogenic
coolers for cooling
Do not require such
bulky, expensive
cryogenic coolers
5. They are expensive both
to produce &run
They are smaller & less
costly
6. Materials used: indium
arsenide, lead sulfide
Materials used:
amorphous silicon,
vanadium oxide
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ADVANTAGES
It shows a visual picture so temperatures over a large area can be
compared
It is capable of catching moving targets in real time
It is able to find deteriorating, i.e., higher temperature components
prior to their failure
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 in shafts, pipes, and other metal or
plastic parts
It can be used to detect objects in dark areas
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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
Only able to directly detect surface temperatures
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APPLICATIONS
Preventive maintenance applications in building systems
Moisture inspection
Medical imaging
Night vision
Military
Conditional monitoring
Veterinary thermal imaging
Research
Process control
Nondestructive testing
Chemical imaging
Volcanology 14
REFERENCES
Roglski A. Chrzanowski K. 2002, “Infrared devices
& Techniques” contributed paper: Opto-electronics
review
www.wikepedia.org
www.howstuffworks.com
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THANK YOU
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