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Night vision


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  • 2. Introduction  Night vision is used to locate an object which is 200 yards away even in moonless, cloudy night  Night vision can work into two different ways, depending on the technology used  They are image enhancement and thermal imaging. Image enhancement works by collecting lower portion of infrared light spectrum  Thermal imaging operates by capturing the upper portion of the infrared light spectrum
  • 3. TYPES OF NIGHT VISION It is broadly classified into two types  Biological Night Vision  Molecules in the rods of the eye undergo a change in shape as light.  Molecules in the human rods is insensitive to the light.  Technical Night Vision  Image intensifier  Thermal imaging
  • 4. Technical Night Vision  Image Intensifier  Night vision amplifies light to achieve better vision .  A conventional lens, captures ambient light.  The gathered light is sent to the image-intensifier tube.  The light energy released electron from the cathode and accelerated.  These electrons enter micro channel plate and bounce off and generate more electron.  Thousands of other electrons to be released in each channel.  Original electrons collide with the channel , exciting atoms and causing other electrons.  New electrons collide with other atoms, creating a chain. 
  • 5. Technical Night Vision (cont..)  In image-intensifier tube, the electrons hit a screen.  The energy of the electrons release photons and create green image on the screen.  The green phosphor image is viewed through another lens.
  • 6. Technical Night Vision (cont..)  Thermal Imaging All objects emit infrared energy as a function of their temperature.  A lens focuses the infrared light.  The focused light is scanned and create temperature pattern.  The pattern created is translated into electric impulses.  The impulses are sent to a circuit board that translates the information into data for the display.
  • 7. Technical Night Vision (cont..) The signal-processing unit sends the information to the is play, and appears as various colors. Thermal images are black and white in nature.
  • 8. NIGHT VISION DEVICES Night vision devices are basically divided into three categories  SCOPES  They are monocular normally handheld or mounted on a weapon. GOGGLES  They are binocular and worn on the head. CAMERAS  Used for transmission or recording of images mostly if the location is fixed.
  • 9. GENERATIONS Generation 0 The earliest (1950's) night vision products were based on image conversion, rather than intensification. Generation 1  Vacuum Tube Technology  Full Moon Operation  Amplification: 1,000  Operating Life: 2,000 Hours
  • 10. GENERATIONS (cont..) Fig:- Generations1 Night vision Sources:
  • 11. GENERATIONS (cont..)  Fiber optic plates collimate incoming light before impacting a photo cathode which releases electrons, which in turn impact a phosphor screen  The excited screen emits green light into a second fiber optic plate, and the process is repeated  The complete process is repeated three times providing an overall gain of 10,000
  • 12. GENERATIONS (cont..) Generation 2  First Micro channel Plate Application  One-Quarter Moon Operation  Amplification: 20,000  Operating Life: 2,500 Hours Generation3  Improved Micro channel Plate & Photocathode  Starlight Operation  Amplification: 40,000  Operating Life: 10,000 Hour
  • 13. GENERATIONS (cont..) Fig:- Generations2 Night vision device Sources:
  • 14. GENERATIONS (cont..)  In second-generation night visions the addition of the micro channel plate (MCP) collimated electron flow and increased the light-amplification gain Current image intensifiers incorporate their predecessor's resolution with additional light amplification  The multi alkali photo cathode is replaced with a gallium arsenide photocathode; this extends the wavelength sensitivity of the detector into the near infrared  The moon and stars provide light in these wavelengths, which boosts the effectively available light by approximately 30%, bringing the total gain of the system to around 30,000
  • 15. Applications Military Law enforcement Hunting Wildlife observation Surveillance Security Navigation Hidden-object detection Entertainment
  • 16. CONCLUSIONS  Night vision devices are basically designed for utmost defensive purposes but the application within the scientific or the civilian range is often prohibited by law.  In present scenario the applications of night vision technology is very essential to combat terrorism which is a major problem being faced by mankind.  It is mainly used in military purposes as well as navigation , surveillance and targeting .  Night vision is used to locate an object which is 200 yards away even in moonless , cloudy night
  • 17. References
  • 18. Thank you!