optics and photonics for defense and security.

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Optics and Photonics for National Defense and
Security
By DIVYA BHARTI Sem. -IV, ISP
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Why Technologies in Battlefields.

• To improve the effectiveness of
• the combatant.
• To minimize casualties.
• For rapid detection and control of nuclear,
  chemical,
• and biological threats and dissemination 

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What are we talking about?

• Range Finders
• Optically guided weapons
• Night vision goggles
• Thermal Imaging
• Laser Guided Munitions
• Direct energy Laser weapons.

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• Range Finders
• It calculates the distance, or range, to a
  desired target
• It can be either handheld or mounted on a tank or
  aircraft.

• Simulating Battlefield Conditions
• Special light bursting gun is used instead of
  real one.
• Target is equipped with light detecting sensors.
• When a burst of light is fired and hits a sensor
  on an "enemy" soldier, the sensor registers the
  light and everyone knows immediately that the
  soldier is "dead.

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• Underwater Communications
• Traditional way using ordinary radio.
• Disadvantages
• Radio waves do not travel well underwater and
  require large antennas to broadcast them long
  distances.
• There is always the risk that the enemy will pick
  up the signal, which immediately reveals the
  sub's location and exposes it to danger.
• Laser communication.
• Message is encoded in green blue pulsed laser
  form, transmitted to satellite and then
  retransmitted to a submarines.
• Travels easily through ocean water.
• Submarine is equipped with a special receiver
  that registers only blue-green light.

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The beam carrying the message is transmitted to a
satellite orbiting high above the ocean. The
satellite then relays the beam down to the sub,
which is equipped with a special receiver that
registers only blue-green light. In less than a
second the sub's computer decodes the signal so
the crew can read the message. If there are any
enemy lookouts nearby it is unlikely they will
know about the signal beam, which the satellite
flashes for only a few millionths of a second.
This is not enough time for the lookouts to see
the beam with their naked eyes. And even if they
have a receiver that detects laser light, it has
to be tuned to receive the exact shade of
blue-green in the beam. Their receiver also has
to be underwater near the sub because that is
where the satellite aims the beam. Meeting these
conditions would be very difficult for the
lookouts, so chances are good that the sub will
get the message and still remain undetected.
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Night Vision Devices (NVD)

• Image Enhancement.
• Increase amount of light reaching the eye
• Light amplification
• Thermal Imaging.
• Collect infrared radiations of the object.

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Image Intensifier

• Amplify existing light.
• Available light (photons) is collected and
  focused on the image intensifier.
• Conversion of photon to electron.
• CAN NOT see in complete dark.

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Image intensifier tube
Converts photons to electrons and back again
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• Thermal imaging
• Every object emits continuous radiation with a
  specific peak in infrared region depending on its
  absolute temperature.
• Device capture the upper portion of the infrared
  light spectrum, which is emitted as heat by
  objects.
• Hotter objects, such as warm bodies, emit more of
  this light than cooler objects like trees or
  buildings.

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How Infrared images form.
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• Thermal Imaging Cameras
• Advantages
• The highest possible thermal sensitivity.
• Able to detect people and vehicles at great
  distances.
• Not affected by bright light sources.
• Able to perform high speed infrared imaging.
• Able to perform multi-spectral infrared imaging.

Day Time image
Night Time image
infrared image
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Laser-Guided Weapon (LGW)
A weapon which uses a seeker to detect laser
energy reflected from a target marked by a laser,
and through signal processing provides guidance
commands to a control system which guides the
weapon to the point from which the laser energy
is being reflected.
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• Major Components
• Laser
• Seeker
• Munitions
• Delivery System
• Target
• Laser
• Light from the laser is reflected and scattered
  of the target.
• Can originate from the ground or from an
  aircraft.
• Typically in near infrared
• Allow for day and night use
• Smoke, dust and chemical particles in the air may
  attenuate or reflect the laser beam.
• Specular reflection is bad.

Indian Laser Guided Bomb
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• Seeker
• Seeker has Riflescope like optics
• Very narrow field of view
• The electronics samples the reflected laser
  energy from the target and corrects its
  trajectory
• Onboard guidance system guides the unit to the
  target

• Why use LGW
• Cheaper
• Higher Accuracy
• less Munitions Required
• less civilian Casualties
• Greater Target Damage
• Simple to convert from Old Munitions

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Airborne Laser Mine Detection System (ALMDS)

• Detect, classify, and localize floating and
  near-surface moored sea mines.
• Use high-powered blue green laser fan beam and
  utilizes the forward motion of the helicopter in
  a push broom configuration to generate volume
  images of surface and near-surface mines. 
• The images are processed by automatic target
  recognition (ATR) algorithms. This configuration
• does not have moving parts and
• allows high system reliability. ALMDS
• is capable of day and night operations
• without any equipment modifications.

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"YAL-1A, is a high-energy laser weapon system for
the destruction of tactical theatre ballistic
missiles. It consists of four lasers, advanced
adaptive optics, sensors, and computers to
locate, track and destroy missiles. 
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• It works like this
• Infrared sensors detect the heat signature of a
  boosting missile and report information to an
  Active Tracking Laser.
• The Active Tracking Laser tracks the missile and
  reports relevant tracking information (distance,
  speed, altitude).
• The Tracker Illuminator Laser scans the target
  and figures out where best to aim the high-energy
  laser.
• The Beacon Illuminator Laser shines on the
  target, determines the amount of atmospheric
  turbulence between the ABL and the target, and
  relays this information to the adaptive optics
  system in the aiming mechanism of the high-energy
  laser.
• The Adaptive Optics system is made of deformable
  mirrors that compensate for atmospheric
  turbulence.
• The COIL laser fires a megawatt beam at the
  target.
• The high-energy laser beam penetrates the skin of
  the target missile and disables or explodes it,
  depending upon where the beam strikes.
• All of the operations are coordinated by computer.

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• Factors that limit laser weapons operational
  utility
• Atmospheric attenuation and turbulence.
• Line-of-sight dependence.
• Minimal effects on hardened structures and
  armored vehicles.
• Single wavelengths that limit the range of
  operational
• conditions in which they are effective.
• Eye safety issues.
• Chemical fuels and exhaust.

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Thank you