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NVG

NVG. Night Vision Goggle Operations. Presented By:. Capt John Withelder 39th Rescue Squadron. HUMOR TIME. Iraqui Navy. Turning Night Into Day. Overview. The visual process Components of Vision NVG Theory and Development NVG Components Types of NVGs Visual Performance

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NVG

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  1. NVG Night Vision Goggle Operations

  2. Presented By: Capt John Withelder 39th Rescue Squadron

  3. HUMOR TIME

  4. Iraqui Navy

  5. Turning Night Into Day

  6. Overview • The visual process • Components of Vision • NVG Theory and Development • NVG Components • Types of NVGs • Visual Performance • NVG Limitations • Welcome to the NVG Lab

  7. The Visual Process • Cone cells - (day vision, require high light, best for resolution and color vision) • Rod cells - (night vision, low level light, best for peripheral vision, blind spot at Fovea)

  8. Components of Vision • Focal Vision • Limited to the central 2° of vision (Fovia) • Consious function, slow process • Allows one to clearly identify objects/read displays • Ambient Vision ( peripheral vision) • subconsious function, primary role to orient an individual in the environment. • Works with focal vision to provide spacial orientation

  9. Components of Vision • Dark adaptation • varies between people • sensitivity increase 10,000 fold first 30 minutes • complete adaptation 30 to 45 minutes • Extreme exposure to bright light may destroy dark adaptation for hours, even days. • NVG image perceived in shades of green using both rods and cones. ( dark adaptation critical)

  10. NVG Theory • Electro-optical system • NVGs collect reflected ambient light • Invert and focus image on image intensifier • Image intensifier convert light into electrons • Electrons stikes phosphor screen creating visible image • Image reinverted by fiber optics and transmitted to eye-piece

  11. NVG Theory • Illuminence (illumination) • light striking an object/surface at a distance • ex. Moonlight striking the ground • Luminance • amount of light reflected from a surface • ex. Moonlight reflected from the terrain • Albedo • ratio between illuminence and luminance • NVGs intensify reflected energy (luminence)

  12. NVG Development World War II IR (Infra-red) exploitations Early 60’s Army NVG work Generation I tubes Heavy/awkward/Starlight Scope Generation II tubes Early 70’s development Microchannel plate Shorter/lighter/helmet mounted Generation III tubes intensifier tube into the near IR spectrum “Gallium Arsenide” photocathode (Starlight level performance) What we use now

  13. NVG DevelopmentGen 2 vs. Gen 3 Performance

  14. NVG Components(Gen 3) • Advanced night vision system • Binocular style, helmet mounted • Amplify visible and near IR energy • Passive process, no emission by goggles • Image is green due to phosphor type used.

  15. NVG Components(Gen 3)

  16. Night Vision Goggles

  17. Types of NVGs Type I Type II • Direct View • USAFAN/AVS-6 ( ANVIS) • Optical performance better • Type used in HC-130/HH60 Ops. • Indirect View • Use of combiner glass to reflect image on HUD • Less obstruction to pilots field of view

  18. NVG Specifications LIMITS: AN/AVS-6AN/AVS-9 VERTICAL MOTION- 19.5mm 16mm FORE AND AFT- 15.8mm 16mm TILT- +/-5 degrees EYE SPAN- 51mm-72mm OBJECTIVE FOCUS- 254mm--> <61cm--> FIELD OF VIEW- 40 degrees MAGNIFICATION UNITY 1X WEIGHT- 500g 790g OPERATING TEMPERATURE- -25F to +125F STORAGE TEMPERATURE- -31F to +159F COST- BETWEEN $7500 and $8500

  19. Visual Performance • Vision limited while using NVGs • Detection ranges increase • Recognition of targets, terrain severly limited • NVGs Do Not Turn Night Into Day !!

  20. NVG Limitations • Field of View (FOV) (peripheral vision) • Current Type I NVGs, 40° FOV • Current Type II NVGs 30° FOV • Normal eye vision FOV 120° x 80° • Resolution capability of 20/25 to 20/40 Snellen • Exceeds eyes unaided night vision of 20/200 to 20/400

  21. NVG Limitations • Depth perception and distance estimation • NVGs degrade capability of distance estimation • NVGs will not correct for sight deficiencies. • NVG use incurres loss of contrast and definition. • Reduction in FOV requires aggressive visual scan technique.

  22. NVG Rescue

  23. FLIR Video

  24. Questions ?

  25. Welcome to the NVG Lab • Review NVG Adjustment video • Wear NVGs in the “visual test lane”

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