NVG

Question 1

What are the 5 major structures of the eye?

Answer 1

• cornea
• iris
• pupil
• lens
• retina

Question 2

What is the purpose of cones in the eye?

Answer 2

• identify colors
• utilized during daylight
• sharp visual acuity due to 1:1 ratio of cone cells to neuron cells
• uses photochemical iodopsin

Question 3

What is the purpose of rods in the eye?

Answer 3

• operate in low illumination
• identify shades of black, grey and white
• 10:1-10,000:1 ratio of rod cells to neuron cells
• utilize photochemical rhodopsin (visual purple)

Question 4

Describe the day blind spot

Answer 4

• exists because the optic disk contains no photoreceptors cells
• covers an area of 5.5-7.5 degrees
• compensated for by binocular vision

Question 5

Describe the night blind spot

Answer 5

• occurs when the fovea is inactive in low light
• covers 5-10 degrees
• an object will fade if stared at for longer than 2 seconds

Question 6

What are the three night vision techniques? (SOS)

Answer 6

• scanning
• Off center viewing
• shapes and silhouettes

Question 7

What are the three types of vision?

Answer 7

• photopic (day)
• mesopic (dawn/dusk/full moonlight)
• scotopic (dimly lit nights/partial moonlight/starlight)

Question 8

Monocular cues (GRAM)

Answer 8

• geometric perspective (LAV)
  - linear perspective
  - apparent foreshortening
  - vertical position in the field
• retinal image size (KITO)
  
  • known size of objects
  • increasing or decreasing size
  • terrestrial association
  • overlapping contours
• Aerial perspective (FLP)
  
  • fading of colors and shades
  • loss of texture and detail
  • position of light source
• Motion Parallax

Question 9

Describe dark adaptation

Answer 9

-The process by which the eyes become more sensitive to low levels of illumination

-optimal night vision acuity approaches its maximum level in about 30 to 45 minutes

• if the eyes are exposed to bright light after dark adaptation, their sensitivity is temporarily impaired
• illness adversely affects dark adaptation due to higher than normal oxygen consumption rate

Question 10

Visual Illusions

FFAACCSSSSVH

Answer 10

• fascination/fixation
• false horizon
• aerial perspective
• autokinesis
• confusion with ground lights
• cratering
• structural
• size-distance
• size constancy
• shape constancy
• vection
• height-depth perception

Question 11

How can you identify deteriorating weather conditions at night under NVGs?
(FLASH)

Answer 11

• fog
• loss of moon or stars
• ambient light levels
• shadows
• halo effect

Question 12

What are the NVG considerations?

CALMWWADSOS

Answer 12

• color
• air/ground speed
• lights
• magnification vs. intensify
• weather
• weapons
• aircraft lighting
• depth perception/distance estimation
• spatial disorientation
• obstacle detection
• scanning techniques

Question 13

Describe the image intensifier of the NVGs.

6 parts

Answer 13

• objective lens
• photocathode
• micro channel plate
• phosphor screen
• fiber optic inverter
• eyepiece lens

Question 14

How does ABC work?

NVGs

Answer 14

Automatic Brightness Control
-adjusts MCP voltage to maintain brightness at preset levels by controlling number of electrons that exit the MCP (micro channel plate)

Question 15

How does BSP work?
(NVGs)

Answer 15

Bright Source Protection

-reduces voltage to the photocathode when exposed to bright light sources

Question 16

What are the NVG characteristics?

DIALVP

Answer 16

• definition : a helmet mounted Light intensification device that allows aircrews to conduct operations at terrain flight altitudes during low ambient light levels, to include overcast conditions
• intensification, not magnification
• acuity : enhances visual acuity from unaided 20/200 to approximately 20/25 under optimal conditions
• Limited field of view : 40°
• Voltage low indicator
• Power supply: batteries, aircraft power, or COPs

Question 17

Describe the counterweight recommendations as pertains to the ANVIS

Answer 17

-recommended initial weight is 12 ounces however, maximum allowable weight is 22 ounces

Question 18

How can the aviator avoid spatial disorientation when using NVGs?

Answer 18

-avoid making drastic changes in attitude and bank angles, use proper scanning and viewing techniques

Question 19

What are the operational defects of the ANVIS?

SEEFFI

Answer 19

• shading
• edge glow
• emission points
• flashing
• flickering
• intermittent operation

Question 20

What are the cosmetic blemishes of the ANVIS?

BBICFO

Answer 20

• bright spots
• black spots
• image disparity
• chicken wire
• fixed pattern noise (honeycomb)
• output brightness variation

Question 21

What is OSAP?

Answer 21

Optimal Site Adjustment Point
-The optimal sight picture when the optical axis of the goggles are aligned with your visual line of sight and the goggles eyepieces are at the maximum distance from your eyes that still allows you to see the full field of view

Question 22

How far/fast does the moon travel in the sky?

Answer 22

Approximately 15 degrees per hour

1 degree every 4 minutes