NIGHT VISION TECHNOLOGY A SEMINAR REPORT

[seminar class]

PRESENTED BY
MANJEERA
ANITHA

---

[attachment=10766]
NIGHT VISION TECHNOLOGY
Introduction
 NVT allows us to see in the dark
 Originally developed for military use
 Now used for site security, surveillance as well as search and rescue
 Evolved from bulky optical instruments in lightweight goggles through the advancement of image intensification technology.
Types of night vision
 Categorized by generations
 Each substantial change NVT establishes a new generation
 Categorized into:
Generation-0
Generation-1
Generation-2
Generation-3
Generation-4
Generation-0
 Created by US Army
 Uses active infrared
 A projection unit called IR illuminator is attached
 Full moon operation
 Use anode in conjunction with cathode to accelerate the electrons
 Problems –acceleration causes distortion of image as well as reduction of life of the tube
 Also, it was quickly duplicated by the hostile nations
Generation-1 (1960’s)
 Uses passive infrared
 Uses ambient light provided by the moon and the stars
 Don’t require a source of projected infrared light
 Don’t work well on cloudy or moonless nights
 One quarter moon operation
 Uses same image-intensifier tube technology as Generation-0
 Same problems as faced by the Generation-0
Generation-2 (1970’s)
 Offer improved resolution and performance over Generation-1 devices
 Considerably more reliable
 Able to see in extreme low light conditions due to the addition of microchannel plate(MCP) to the image-intensifier tube
 The images are less distorted and brighter
Generation-3 (1990’s)
 Currently used by the US Army
 Better resolution and sensitivity
 Photocathode is made up of Gallium Arsenide
 MCP is coated with an ion barrier
 Tube life is increased
Generation-4 (2000’s)
 Known as “filmless and gated” technology
 Shows significant improvement in both high- and low-level light environments
 No ion barrier in MCP
 Responds quickly to different lightning conditions
 Reduced background noise
 Enhances signal to noise ratio
 Images are less distorted and brighter
Thermal imaging
 This technology operates by capturing upper portion of the infrared light spectrum, which is emitted as heat
 Hotter objects emit more of this light than the cooler objects
 These elements then create a thermogram
 Thermogram àelectric pulsesà display data
WORKING
 A special lens focuses the IR light emitted by all of the objects in view.
 The focused light is scanned by a phased array of IR detected elements.
 This scanning create a very detailed temperature pattern called thermogram.
 The thermogram created by the detector elements is translated into electric impulses.
Thermal imaging
Thermal imaging devices
 Two types:
1. Uncooled.
2. Cryogenically cooled.
 Great for detecting people or working in near-absolute darkness
Image Enhancement
 It is also known as Image intensification
 Relies on image intensifier tube to collect an amplify infrared and visible light
 Lens captures the light which is then sent to image intensifier tube
 It has photocathode that converts photons into electrons
 When electrons pass through MCP ,more electrons are presented
 This causes chain reaction where atoms are released
 Electrons reach phosphor screen and photons are released
 Those phosphor create green image
Performance Attributes
 Sensitivity (photo response)- tube’s ability to detect the available light
 Signal- plays a key role in night vision’s performance
 Resolution- ability to dissolve detail in the image
Technical Characteristics
 Textures, Light and Dark
 Depth Perception
 Fog and Rain
 Honeycomb
 Spots
Equipments
Three categories
 Scopes
 Goggles
 Cameras
Equipments
 Scopes- monocular, handheld, better look at a specific object and then return to normal viewing conditions.
 Goggles- binocular, handheld or worn, excellent for constant viewing
 Cameras- send the image to a monitor for display or to a VCR for recording.
Applications
 Military
 Law enforcement
 Hunting
 Wild life observation
 Surveillance
 Security
 Navigation
 Hidden-object detection
 Entertainment
ADVANTAGES
 Night vision devices are compact in size and is easily portable.
 It is widely used in military purposes so it is reliable.
 It’s working is very simple so it is easy to use.
 It is designed for a long life.
DISADVANTAGES
 Night vision devices is very costly.
 It cannot properly be used in rain and fog as it degrade its performance.
 Poor quality images due to black spots.
Conclusions
 Although the term ``night vision'' currently encompasses three distinct technologies, it is the evolution of image intensification technology that first made devices practical and widely used.
 Their success was the result of advancements in light amplification and resolution techniques.