How Fiber Optic Temperature Sensor Works

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Fiber Optic Temperature Measurement Technology
OPERATING PRINCIPLE

• Based on a well known and reproducible phenomenon
• The band-gap variation in the absorption spectrum
  of the semiconductor GaAs (Gallium Arsenide)
  with respect to temperature
• GaAs can also be looked at as a variable optical
  filter (low pass)
• Wavelengths towards visible are blocked
• Wavelengths towards infrared are transmitted
• A Direct Contact temperature sensor
• GaAs material properties will never change with
  time, ever !
• No DRIFT
• No RECALIBRATION

100
0
? Visible
Infrared ?
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Fiber Optic Temperature Measurement Technology

• SYSTEM DESIGN
• The System consists of

FIBER OPTIC TEMPERATURE SYSTEM

• Light source
• Optical coupler
• Rugged Spectrometer
• Electronics for Data Processing, Storage
  Visualization

While Light Source
GaAs Sensor

• An optical fiber delivers white light to the
  semiconductor GaAs sensor glued at the Probe Tip
• Some of the light is absorbed Depending on the
  temperature of the GaAs Crystal at the Probe Tip
• The light is reflected by a dielectric mirror and
  returns through the same fiber for analysis by
  the on-board Spectrometer
• Highly reliable monitors suited to automotive
  environments

Fiber Optic Probe
Optical Coupler
Spectrometer
Dielectric
Mirror
Fiber Cladding
Coating
Injected Light
Reflected Light
GaAs Crystal (Sensor)
Fiber Core
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Fiber Optic Sensors Immunity to Environments
High voltage Greater than 1200kV
Radiation Nuclear
Radio Frequency (100 kHz up to 10 MHz)
Magnetic Field Greater than 25 Tesla
Chemicals All pH levels (0 14)
Vibration 10g Force
Microwave (300MHz to 300GHz)
Bio Safe Sterile Environments

• No Need for Isolation Highly dielectric strength
• Avoid complex compensation and Calibration
  Immune to Noise
• Ultra Fast Response Accurate Thermal Profiling
• Smaller Size and Intrinsically Safe Easy to use
  and handle Sensors
• Explosion Proof Suitable for Explosive
  Environments

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Benefits of Fiber Optic Sensors over Traditional
Sensors

• Electric vehicles are going to 1000V, 700A for
  cars and 2400V, 1000A for trucks
• Traditional thermocouples are too slow and
  significant limitation above 200V
• Thermocouple output is in millivolts and gets
  affected by Electric and Magnetic fields
• Safety Risk from Thermocouples Risk of short
  circuit at higher voltages, Corrosion etc.
• Thermocouples are Non-Linear Sensors are
  non-linear, require complex compensation
• Thermocouples are large not suitable to fit into
  tiny spaces on PCBs, Power Electronics, Charging
  Points
• Slower Response Thermocouples are not fast
  enough for accurate thermal profiling
• Variation from Batch to Batch Impact accuracy
  and repeatability of testing
• Susceptible to High Voltage and Magnetic Fields
• Thermocouples are not suitable for Explosive
  Environments

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Fiber Optic Temperature Sensors applications

• Transformer Winding Hot Spot Monitoring
• Switchgear Temperature Monitoring
• Motor Winding Temperature Monitoring
• Cable Termination Temperature

• Microwave Heating
• Microwave Digestion
• Microwave Ablation
• RF / Microwave Drying
• Food Packaging
• Soil decontamination

RF / Microwave
Energy/ Utilities

• EV Motors
• EV Battery Cells
• EV Battery Module
• EV Battery Pack
• Power Electronics
• Charging Equipment

Application for Fiber Optic Temperature Sensors

• Glass Manufacturing
• Process and Control
• Mining Applications

E-Mobility
Industrial

• MRI Machines / Coils
• Sensor for Catheters
• CT scan, PAT scan
• Clinical Trails
• Cancer Treatment

• Cryogenic Research
• Pharmaceutical Research
• Consumer Product Research
• Environmental Research

Research Lab
Medical
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