Alok

THERMAL(IR) IMAGING TECHNOLOGY BY

PUNEET GOYAL Email: [email protected]

SANT LONGOWAL INSTITUTE OF ENGG. & TECHNOLOGY, LONGOWAL

Imaging Basics

Electromagnetic Spectrum

Visible

THERMAL IMAGING (THERMOGRAPHY) THERMOGRAPHY IS CONVERSION OF INFRARED(HEAT) RADIATION INTO A REAL TIME VIDEO PICTURE

THERMOGRAM IS PICTORIAL REPRESENTATION OF TEMPERATURE AND EMMISSIVITY DIFFERENCES ACROSS THE TARGET WITH RESPECT TO BACKGROUND

Physics Behind Plank’s law of radiation

To determine over a spectral band of interest we integrate the Plank’s curve

Physics Behind cont.. Stefan Boltzman Law The total energy emitted at all wavelength by a black body is related to the absolute temperature as

Wb= Where

T4

Wb : total energy emitted : constant=5.67x10-18 m-2K-4 T

: temperature of the object

Why Thermal Imaging?

It is quite easy to see everything during the day..

...but at night, you can see very little.

Thermal imaging lets you see again.

Why Thermal Imaging? Cont….

 OPERATES IN TOTAL DARKNESS : TRULY PASSIVE  LESS AFFECTED BY SMOKE, DUST OR LIGHT RAIN  CANNOT BE BLINDED BY SEARCH LIGHT & FLARES  REVEALS THE THERMAL DETAILS OF THE SCENE  DETECTS THERMAL FOOT PRINTS  LONGER DETECTION RANGE POSSIBLE

How does aWhich TI converts work? Which collects the infra red radiation and focus it on to the detector array

infra red radiation in to electrical signal

Different Elements of Imaging Process TARGET

 TYPE  SIZE (H x V)  EMITTANCE THERMAL CONTRAST  MOTION  DAY TIME

ATMOSPHERE

ABSORPTIONS TEMPERATURE VISIBILITY

PLATFORM

 TYPE OF VIBRATION  SPEED  ALTITUDE

SENSOR/DEVICE

 RESOLUTION SYSTEM PARAMETERS  DETECTOR  SIGNAL PROCESSING

DISPLAY

      

SIZE OF SCREEN RESOLUTION BRIGTHNESS CONTRAST

OBSERVER

 TRAINING   EXPERIENCE    AGE    IQ    EYE MTF

Infrared Detector Types Thermal Detectors (Uncooled Operation): Detector element is sensitive to the change in its temperature due to variation in incident radiant power, resulting in change in material property. Response of the detector is directly proportional to the energy absorbed. Bolometer : A temperature change causes a change in resistance of detector material. Thermocouple : Current flows due to change in temperature Typically operates at or near room temperature with modest sensitivity, but available at low cost

Infrared Detector Types cont.. Photon (Quantum) Detectors (Cooled) Detector element consisting of Infrared sensitive semiconductor like MCT, InSb etc. encapsulated in a dewar and is sensitive to the change in its electrical property brought by fluctuations in the number of incident photons. Response of detector is directly proportional to photon absorbed. PC Mode Detector : Variation in incident Photon cause corresponding variation of current through the detector. PV Mode Detector : It absorbs photons to create an e--h pair across p-n junction. This current is generated without the need for external bias. Typically operates at cryogenic temperatures(4-200K)with high sensitivity, but at higher cost

Uncooled Detectors – Enabling Technology

Cooled Market segment       

High performance Long range High resolution Relatively high cost Heavy High power Cool down time required

Uncooled Market segment        

Short range Low resolution Low cost Small size, light Low power Noiseless Instant operation readiness Maintenance free

Complementary: Not Competing

APPLICATIONS OF THERMAL IMAGING •MILITARY •INDUSTRIAL •MEDICAL •POLICE •FIRE SAFETY •MARINE •FORESTRY •NEWS MEDIA

APPLICATIONS - Military •AIR SURVEILLANCE AND RECONNAISANCE •TARGET ACQUISITION FOR MISSILE LAUNCHING •TARGET DETECTION AND ACQUISITION IN FIRE CONTROL SYSTEMS •NIGHT BOMBING •INFRARED SEARCH AND TRACK SYSTEMS •INFRARED SEEKERS •HAND HELD THERMAL IMAGER FOR TROOPS •MINE DETECTION

APPLICATIONS - Military

(Missiles (end game Missiles

Tank sighting & Rifle sights Smart Munitions

Missiles

APPLICATIONS - Military Surveillance Helicopter with FLIR

Aerial IR image of tank

Factory & ships in backgound

APPLICATIONS - Military TARGET ACQUISITION FOR MISSILE LAUNCHING

APPLICATIONS - Military

iR image of Battleship

Aerial IR image of tank

Factory & ships in backgound iR image of Bridge and coastline

APPLICATIONS - Medical

Inflammation in cervical region

Low back asymmetry

along with extremely poor circulation in arms (blue colors).

APPLICATIONS - Medical

Excellent symmetry in the lower extremities

Asymmetry is due to fracture of the fibula on left leg

Muscle tear in the upper leg. Asymmetrical lower extremities.

APPLICATIONS - Medical

Blood Circulation

Blood Flow Vascular Scan

APPLICATIONS - Police •SURVEILLANCE •RIOT CONTROL

APPLICATIONS -Industry

Infrared facility roof survey. The brighter shades on this image represent trapped moisture on the roof

Heat loss of a residential home

APPLICATIONS -Industry

Tank level analysis

Thermal Imagers Developed In India

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