NVGNVGNight Vision Goggle OperationsNight Vision Goggle Operations

Presented By:Presented By:

Capt John WithelderCapt John Withelder

39th Rescue Squadron39th Rescue Squadron

HUMOR TIMEHUMOR TIME

Iraqui Navy

Turning Night Into DayTurning Night Into Day

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

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)

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

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)

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

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)

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

NVG DevelopmentNVG DevelopmentGen 2 vs. Gen 3 PerformanceGen 2 vs. Gen 3 Performance

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.

NVG ComponentsNVG Components(Gen 3)(Gen 3)

Night Vision GogglesNight Vision Goggles

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

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

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 !!

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

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.

NVG RescueNVG Rescue

FLIR VideoFLIR Video

Questions ?Questions ?

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”