Night vision


Published on

Published in: Technology, Business

Night vision

  2. 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. 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. 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. 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. 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. 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. 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. 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. 10. GENERATIONS (cont..) Fig:- Generations1 Night vision Sources:
  11. 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. 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. 13. GENERATIONS (cont..) Fig:- Generations2 Night vision device Sources:
  14. 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. 15. Applications Military Law enforcement Hunting Wildlife observation Surveillance Security Navigation Hidden-object detection Entertainment
  16. 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. 17. References
  18. 18. Thank you!