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OPTICAL SENSORS AND
THEIR APPLICATIONS
PRESENTED BY
ANSA M B.
INTC1517512

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TOPICS INCLUDED IN THIS
PRESENTATION
 INTRODUCTION
 WHY OPTICAL SENSORS ?
 PRINCIPLE OF OPTICAL SENSORS
 CLASSIFICATION AND COMPARISON
 SOME INTERESTING APPLICATIONS
 WHERE DO WE GO FROM HERE ?

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INTRODUCTION
 NEW REVOLUTION OF OPTICAL
FIBER SENSORS
 IT IS A “SPIN-OFF” FROM OTHER
OPTICAL TECHNOLOGIES
 SEEING THE POTENTIAL IN
SENSING APPLICATIONS –
DEVELOPED AS ITS OWN FIELD

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WHY OPTICAL SENSORS
 ELECTROMAGNETIC IMMUNITY
 ELECTRICAL ISOLATION
 COMPACT AND LIGHT
 BOTH POINT AND DISTRIBUTED
CONFIGURATION
 WIDE DYNAMIC RANGE
 AMENABLE TO MULTIPLEXING

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TEMPERATURE CHEMICAL
SPECIES
PRESSURE FORCE
FLOW RADIATION
LIQUID LEVEL pH
DISPLACEMENT HUMIDITY
VIBRATION STRAIN
ROTATION VELOCITY
MAGNETIC
FIELDS
ELECTRIC
FIELDS
ACCELERATION ACOUSTIC
FIELDS
OPTICAL SENSOR MEASURANDS

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WORKING PRINCIPLE
• LIGHT BEAM CHANGES BY THE
PHENOMENA THAT IS BEING MEASURED
• LIGHT MAY CHANGE IN ITS FIVE OPTICAL
PROPERTIES i.e INTENSITY, PHASE,
POLARIZATION,WAVELENGTH AND
SPECTRAL DISTRIBUTION

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SENSING DETAILS
EP(t)cos[ωt+θ(t)]
• INTENSITY BASED SENSORS – EP (t)
• FREQUENCY VARYING SENSORS - ωP(t)
• PHASE MODULATING SENSING- θ(t)
• POLARIZATION MODULATING FIBER SENSING

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CLASSIFICATION
 EXTRINSIC SENSORS
WHERE THE LIGHT LEAVES THE FEED OR
TRANSMITTING FIBER TO BE CHANGED BEFORE
IT CONTINUES TO THE DETECTOR BY MEANS
OF THE RETURN OR RECEIVING FIBER

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CLASSIFICATION (contd.)
 INTRINSIC SENSORS
INTRINSIC SENSORS ARE DIFFERENT IN THAT THE
LIGHT BEAM DOES NOT LEAVE THE OPTICAL FIBER
BUT IS CHANGED WHILST STILL CONTAINED WITHIN IT.

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COMPARISON OF THE TWO TYPES
EXTRINSIC INTRINSIC
APPLICATIONS-
TEMPERATURE,
PRESSURE,LIQUID
LEVEL AND FLOW.
LESS SENSITIVE
EASILY MULTIPLEXED
 INGRESS/ EGRESS
CONNECTION
PROBLEMS
EASIER TO USE
LESS EXPENSIVE
APPLICATIONS-
ROTATION,
ACCELERATION, STRAIN,
ACOUSTIC PRESSURE
AND VIBRATION.
MORE SENSITIVE
TOUGHER TO MULTIPLEX
REDUCES CONNECTION
PROBLEMS
MORE ELABORATE
SIGNAL DEMODULATION
MORE EXPENSIVE

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SENSOR TYPES
CHEMICAL SENSORS
 REMOTE SPECTROSCOPY
 GROUNDWATER AND SOIL CONTAMINATION
 MAJOR PLAYERS IN CHEMICAL SENSORS
1) PHARMACIA BIOTECH (SWEDEN)
2) FIBERCHEM
3) THE QUANTUM GROUP
TEMPERATURE SENSORS
 LARGEST COMMERCIALLY AVAILABLE SENSORS
 RANGE -40 deg C TO 1000 deg C
 US-SMALL COMPANIES, JAPAN- HITACHI n
SUMITOMO

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STRAIN SENSORS
 FIBER BRAGG GRATINGS (FBG)
TECHNOLOGY
 SENSES AS LITTLE AS 9 MICROSTRAIN
 NRL and UNITED TECHNOLOGY
RESEARCH
BIOMEDICAL SENSORS
 SPECTROSCOPIC BIOMEDICAL SENSORS
 CO 2, O 2 and pH CAN BE MEASURED
SIMULTANEOUSLY
 FLOW MONITORING BY LASER
DOPPLERIMETRY

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 FIBERS – OPTHALMOLOGIC APPLICATION
ELECTRICAL AND MAGNETIC
SENSORS
 APPEALING- INHERENT DIELECTRIC
NATURE
 LESS SENSITIVE TO ELECTROMAGNETIC
INTERFERENCE
 SMALL SIZE AND SAFER
 THEY ARE ALMOST ALWAYS HYBRID
 ABB CORPORATION RESEARCH CENTER
ROTATION SENSOR
 BASED ON THE SAGNAC EFFECT

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 TWO TYPES RING LASER GYROSCOPE
(RLG) AND FIBER OPTIC GYROSCOPE
(FOG)
 US COMPANIES PURSUING HIGH
PERFORMANCE FOG’s (HONEYWELL,
LITTON, NORTHRUP, ALLIED SIGNAL etc.)
PRESSURE SENSORS
 EARLIER BASED ON PIEZORESISTIVE
TECHNIQUE
 BASED ON MOVABLE DIAPHRAGM
 HIGH PERFORMANCE- (POLARIZATION
BASED SENSORS)
 OPERATING PRESSURE RANGES FROM 0-
70,000 torr

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DISPLACEMENT AND POSITION
SENSORS
 ONE OF THE FIRST OPTOELECTRONIC
SENSORS TO BE DEVELOPED.
 SIMPLE SENSORS RELY ON THE CHANGE
IN RETROREFLECTANCE DUE TO A
PROXIMAL MIRROR SURFACE
 ALSO REFERRED AS LIQUID LEVEL
SENSORS

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APPLICATIONS
 MILITARY AND LAW ENFORCEMENT
THIS SENSOR ENABLES LOW LIGHT IMAGING AT TV FRAME
RATES AND ABOVE WITHOUT THE LIMITATIONS OF VACUM TUBE
BASED SYSTEMS.

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NIGHT VISION CAMERA (contd.)
COMPRISES OF :
 AMPLIFIED CCD SENSOR
 ANTI BLOOMING TECHNOLOGY
 CRYSTAL POLYMER SHUTTER
ADVANTAGES :
 EXCEPTIONAL DAY LIGHT RESOLN.
 IMMUNE TO OVER EXPOSURE
 VERY HIGH CONTARAST LEVELS
 NO HALOING OR SCINTILLATIONS

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BIOMETRICS
YOUR FACE, FINGERS AND EYES IN A WHOLE
NEW LIGHT
• IMAGE CAPTURE
• IMAGE PROCESSING
• FEATURE EXTRACTION
• FEATURE COMPARISON

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PARTIAL DISCHARGE DETECTION
USES OPTICAL FIBER SENSORS
OPTICAL FIBER SENSORS ARE BEING TESTED FOR USE
IN DETECTING PARTIAL DISCHARGES IN ELECTRICAL
TRANSFORMERS. PINPOINTING SUCH DISCHARGES IS
ESSENTIAL TO PREVENTING INSULATION BREAKDOWN
AND CATASTROPHIC FAILURES.

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CONCLUSIONS
LOOKING AT THE INDUSTRY TRENDS
IN THE PAST 2 DECADES AND THE
EXPONENTIAL CURVE IT SEEMS TO
ME THAT THERE IS GOING TO BE A
LOT OF RESEARCH AND
IMPROVEMENTS TO THE EXISTING
SENSORS
OPTICAL SENSORS ARE HERE TO
STAY !!!!

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THANK YOU.