nvg
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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 - PowerPoint PPT PresentationTRANSCRIPT
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NVGNVGNight Vision Goggle OperationsNight Vision Goggle Operations
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Presented By:Presented By:
Capt John WithelderCapt John Withelder
39th Rescue Squadron39th Rescue Squadron
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HUMOR TIMEHUMOR TIME
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Iraqui Navy
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Turning Night Into DayTurning Night Into Day
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OverviewOverview• The visual processThe visual process
• Components of VisionComponents of Vision
• NVG Theory and Development NVG Theory and Development
• NVG ComponentsNVG Components
• Types of NVGsTypes of NVGs
• Visual PerformanceVisual Performance
• NVG LimitationsNVG Limitations
• Welcome to the NVG LabWelcome to the NVG Lab
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The Visual ProcessThe Visual Process
• Cone cells - (day vision, require high light, best Cone cells - (day vision, require high light, best for resolution and color vision)for resolution and color vision)
• Rod cells - (night vision, low level light, best for Rod cells - (night vision, low level light, best for peripheral vision, blind spot at Fovea)peripheral vision, blind spot at Fovea)
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Components of Vision Components of Vision
• Focal VisionFocal Vision– Limited to the central 2° of vision (Fovia)Limited to the central 2° of vision (Fovia)
– Consious function, slow processConsious function, slow process
– Allows one to clearly identify objects/read displaysAllows one to clearly identify objects/read displays
• Ambient Vision Ambient Vision ( peripheral vision)( peripheral vision)
– subconsious function, primary role to orient an subconsious function, primary role to orient an individual in the environment.individual in the environment.
– Works with focal vision to provide spacial orientationWorks with focal vision to provide spacial orientation
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Components of VisionComponents of Vision
• Dark adaptationDark adaptation– varies between peoplevaries between people– sensitivity increase 10,000 fold first 30 minutessensitivity increase 10,000 fold first 30 minutes– complete adaptation 30 to 45 minutescomplete adaptation 30 to 45 minutes– Extreme exposure to bright light may destroy Extreme exposure to bright light may destroy
dark adaptation for hours, even days.dark adaptation for hours, even days.– NVG image perceived in shades of green using NVG image perceived in shades of green using
both rods and cones. both rods and cones. ( dark adaptation critical)( dark adaptation critical)
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NVG TheoryNVG Theory• Electro-optical systemElectro-optical system
• NVGs collect reflected ambient lightNVGs collect reflected ambient light
• Invert and focus image on image intensifierInvert and focus image on image intensifier
• Image intensifier convert light into electronsImage intensifier convert light into electrons
• Electrons stikes phosphor screen creating Electrons stikes phosphor screen creating visible imagevisible image
• Image reinverted by fiber optics and Image reinverted by fiber optics and transmitted to eye-piecetransmitted to eye-piece
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NVG TheoryNVG Theory• Illuminence (illumination)Illuminence (illumination)
– light striking an object/surface at a distancelight striking an object/surface at a distance– ex. Moonlight striking the groundex. Moonlight striking the ground
• LuminanceLuminance– amount of light reflected from a surfaceamount of light reflected from a surface– ex. Moonlight reflected from the terrainex. Moonlight reflected from the terrain
• AlbedoAlbedo– ratio between illuminence and luminanceratio between illuminence and luminance– NVGs intensify reflected energy (luminence)NVGs intensify reflected energy (luminence)
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NVG DevelopmentNVG 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
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NVG DevelopmentNVG DevelopmentGen 2 vs. Gen 3 PerformanceGen 2 vs. Gen 3 Performance
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NVG ComponentsNVG Components(Gen 3)(Gen 3)
• Advanced night vision systemAdvanced night vision system– Binocular style, helmet mountedBinocular style, helmet mounted
• Amplify visible and near IR energyAmplify visible and near IR energy• Passive process, no emission by gogglesPassive process, no emission by goggles• Image is green due to phosphor type used.Image is green due to phosphor type used.
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NVG ComponentsNVG Components(Gen 3)(Gen 3)
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Night Vision GogglesNight Vision Goggles
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Types of NVGsTypes of NVGs
• Direct ViewDirect View
• USAFUSAF AN/AVS-6 AN/AVS-6 ( ANVIS)( ANVIS)
• Optical performance betterOptical performance better
• Type used in HC-130/HH60 Type used in HC-130/HH60 Ops.Ops.
Type IType I Type IIType II
• Indirect ViewIndirect View
• Use of combiner glass to Use of combiner glass to reflect image on HUDreflect image on HUD
• Less obstruction to pilots Less obstruction to pilots field of viewfield of view
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NVG SpecificationsNVG Specifications
LIMITS:
AN/AVS-6 AN/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
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Visual PerformanceVisual Performance
• Vision limited while using NVGsVision limited while using NVGs
• Detection ranges increaseDetection ranges increase
• Recognition of targets, terrain severly limitedRecognition of targets, terrain severly limited
• NVGs Do Not Turn Night Into Day !!NVGs Do Not Turn Night Into Day !!
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NVG LimitationsNVG Limitations
• Field of View (FOV) Field of View (FOV) (peripheral vision)(peripheral vision)
– Current Type I NVGs, 40° FOVCurrent Type I NVGs, 40° FOV
– Current Type II NVGs 30° FOVCurrent Type II NVGs 30° FOV
– Normal eye vision FOV 120° x 80°Normal eye vision FOV 120° x 80°
• Resolution capability of 20/25 to 20/40 SnellenResolution capability of 20/25 to 20/40 Snellen– Exceeds eyes unaided night vision of 20/200 to 20/400Exceeds eyes unaided night vision of 20/200 to 20/400
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NVG LimitationsNVG Limitations
• Depth perception and distance estimationDepth perception and distance estimation– NVGs degrade capability of distance estimationNVGs degrade capability of distance estimation
• NVGs will not correct for sight deficiencies.NVGs will not correct for sight deficiencies.
• NVG use incurres loss of contrast and NVG use incurres loss of contrast and definition.definition.
• Reduction in FOV requires aggressive visual Reduction in FOV requires aggressive visual scan technique.scan technique.
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NVG RescueNVG Rescue
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FLIR VideoFLIR Video
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Questions ?Questions ?
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Welcome to the NVG LabWelcome to the NVG Lab
• Review NVG Adjustment videoReview NVG Adjustment video
• Wear NVGs in the “visual test lane”Wear NVGs in the “visual test lane”