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Chegg Decks > NVG_Notes_deck > Flashcards

NVG_Notes_deck Flashcards

1
Q

Light, in the form of photons, ___

A

reflects off objects in the field of view and enters the eye.

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2
Q

What is the Cornea?

A

the transparent protective tissue located over the front of the eye.

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3
Q

What does the pupil allow?

A

It allows light to enter the eye and stimulate the retina.

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4
Q

What is the purpose of the Iris?

A

The iris contains the ciliary muscle, which automatically adjusts the size of the pupil and regulates the amount of light entering the eye.

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5
Q

What is the purpose of the lens and where is it located?

A

The lens flexes so the light entering the eye is properly focused on the retinal walllocated behind the pupil

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6
Q

The lens is flexible when the individual is young and hardens with age. What does this cause?

A

This causes presbyopia, a slight nearsightedness due to reduced flexibility of the lens

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7
Q

What is the Retina?

A

A thin multi-layered membrane which covers most of the back of the eye. It contains many tine photoreceptor cells known as rods and cones.

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8
Q

How are light levels defined?

A

Light levels are defined as daylight, twilight, or night with a percentage of illumination. 100% illumination is defined as the light level provided by a full moon at maximum azimuth on a clear night.

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9
Q

Retinal photoreceptor cells are named for their shape. What is the primary use of Cone cells and what is the primary use of Rod cells?

A

Cone cells are used primarily for day or high intensity light vision. They provide color vision, but function only in high illumination. The lowest light level in which the cones can function is 50% illumination.Rod cells are always functioning, to varying degrees. During daylight, they provide vision in the peripheral regions. Can’t distinguish colors, but have a higher sensitivity to light than cones. Dimmest level that rods can function is approx. 0%.

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10
Q

Cones are almost exclusively concentrated in the center vision. What is the high-concentration area called and what is it responsible for?

A

The Fovea - this tiny area is responsible for central vision and provides the highest resolution. 85% of visual information comes from this area.There are no rod cells in the fovea - night blind spot

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11
Q

What is the Optic Disk?

A

The optic disk is where the optic nerve enters the retina. Because the optic disk contains neither rods nor cones, nothing can be seen by that part of the retina.day blind spot

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12
Q

What is the Parafovea?

A

The area between the fovea and the periphery, contains both types of photoreceptor cells.

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13
Q

The peripheral area of the retina contains only ___ and is ___.

A

rodsmuch more sensitive to movement and light than the fovea and parafoveal regions

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14
Q

What are the three types of vision?

A

PhotopicMesopicScotopic

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15
Q

What is Photopic vision?

A

Photopic vision is experienced during daylight or under high levels on artificial illuminations. Cones concentrated in the fovea centralis are primarily responsible for vision in bright light.

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16
Q

What is Mesopic vision?

A

The transition zone between photopic and scotopic vision, where the level of illuminations varies between daylight and 50% illumination. Both rods and cones function over a wide range of light intensity levels and, at intermediate levels of illumination, they function simultaneously.

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17
Q

What is Scotopic vision?

A

experienced in light environments below 50%, rods are the primary source of visual input.Visual acuity decreases to 20/200 or less and color perception is lost

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18
Q

Both rods and cones contain light-sensitive chemicals called ___. The ___ in the rods is called ___.

A

photopigments.photopigments, rhodopsin

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19
Q

What bleaches out rhodopsin?

A

high light levels bleach out rhodopsin, making the rods less effective.

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20
Q

The average time required to attain the greatest sensitivity or adaptation to a dark environment is ___.

A

30 to 45 minutes

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21
Q

What color sunglasses does the Army recommend?

A

dark sunglasses with a neutral gray tint.

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22
Q

___ deficiency hinders production of rhodopsin.

A

Vitamin A

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23
Q

Flash blindness. The degree of impairment depends on the ___.

A

intensity and duration of exposure.

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24
Q

Depending on brightness (intensity) and exposure duration or after repeated exposures, complete dark adaptation recovery time ___.

A

can range from 5 to 45 minutes depending.

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25
Q

Cockpit illumination is not and adjustment to “set and forget.” Cockpit illumination should be ___.

A

kept illuminated at the lowest easily readable level.

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26
Q

Visual acuity is the ___

A

ability to resolve detail in an object.

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27
Q

The night blind spot occurs due to ___. The night blind spot is compensated for by ___.

A

the total absence of rod cells in the fovea and the lack of cone cell stimulation within the parafoveal regions.using proper scanning techniques and off-center viewing.

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28
Q

The day blind spot is ___. What compensates for the day blind spot?

A

offset from the center of the retina. No cones or rods are present at the attachment point.Viewing with binocular vision

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29
Q

What scanning technique should be used during unaided flight?

A

Stop-turn-stop-turn motion scanning technique.

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30
Q

Distance estimation and depth perception cues can be ___

A

Binocular or monocular

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31
Q

What are the types of monocular cues?

A

Geometric perspective - object appears to have different shape when it is viewed at varying distances and from different anglesRetinal Image Size - image focused on the retina is perceived by the brain to be of a given sizeAerial Perspective - object’s clarity and its shadow are perceived by the brain and cues for estimating distanceMotion parallax - apparent, relative motion of stationary objects as viewed by a moving observer.

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32
Q

The factors that aid in determining distance using the retinal image are ___.

A

Known size of objectsIncreasing and decreasing size of objectsTerrestrial associationOverlapping contours

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33
Q

Define motion parallax.

A

It is the apparent, relative motion of stationary objects as viewed by a moving observer. Judging Airspeed and Direction.

34
Q

Describe the False Horizon Illusion.

A

occurs when a pilot confuses cloud formations with the horizon or ground.

35
Q

Define Fascination or fixation.

A

When flying, can be separated into two categories: task saturation and target fixation.TS - become so engrossed with a problem or task they fail to properly scan outside the aircraftTF - ignore orientation cues and focus their attention on an object or goal.

36
Q

Define vection (induced motion illusion).

A

falsely perceived self-motion in relation to another object’s motion

37
Q

Define autokenisis.

A

after about 6 to 12 seconds of visually fixating on the light, an individual perceives movement at up to 20 degrees in any particular direction or in several directions in succession, although there is no actual object displacement.

38
Q

Position lights (using ANVIS). ANVIS is more sensitive to red lights than green lights. This causes a ___

A

tendency to drift in the direction of the red light toward the area of greater visibility.

39
Q

The aircrew should treat visual obstacles, such as shadows or dust clouds the same as physical obstacles. Takeoff from a hover should be ___

A

performed as an ITO

40
Q

Approaches can be made to the ground or terminate at a hover. Field LZ approaches are normally planned to terminate at ___

A

a hover because it is difficult to determine the surface condition.

41
Q

The objective lens contains a “minus-blue” coating. This is a special coating in the objective lens of the ANVIS that ___

A

filters out light from the instrument panel and NVG compatible supplemental cockpit lights.This makes the ANVIS “blind” to the lighting so the glare does not interfere with viewing outside the aircraft.

42
Q

The Image Intensifier is an electronic device that amplifies light energy. The power supply circuitry also provides ___.

A

automatic brightness control (ABC)bright-source protection (BSP)

43
Q

Image Intensifier. What does ABC do?

A

automatically reduces the voltages to the MCP (microchannel plate) to keep the image intensifier’s brightness within a set limit.creates and maintains a stable image for the aviator, and prevents the NVG output from becoming bright enough to impact the aviator’s dark adaptation.

44
Q

Image intensifier. What does the BSP do?

A

reduces the voltage to the photocathode when the ANVIS is exposed to bright light sources.

45
Q

What are the components of the Image Intensifier?

A

PhotocathodeMicro-channel Plate (MCP)Fiber-optic inverter

46
Q

What is the function of the Eyepiece Lens?

A

The function of the eyepiece lens is to focus the image from the fiber-optic inverter onto the eye, adjusting for individual eye acuity.

47
Q

TRUE or FALSE. The eyepiece diopter adjustment is not intended to compensate for corrective lenses.

A

TRUEIf your DD Form 2992 states that corrective lenses will be used for flight, then lens correction must be used with ANVIS

48
Q

The ANVIS is a ___ that amplifies light and provides sufficient imagery for flying from overcast starlight to moonlight conditions.

A

passive light amplification/intensification system

49
Q

What is the optimal FOV for the ANVIS?

A

40 degrees

50
Q

How much does the ANVIS weigh?

A

20.8 oz

51
Q

What is the best sight you can have when wearing the ANVIS? Under worst-case conditions, what is the worst visual acuity?

A

20/2520/70

52
Q

The ANVIS has a ___ force breakaway capability.

A

10 to 15 gram

53
Q

As illumination drops below 50%, visual acuity degrades more rapidly, causing the ___ around light sources to be more pronounced.

A

halo effect

54
Q

As illumination levels drop below 35%, ___ becomes more apparent.

A

scintillation (static)

55
Q

The halo in the ANVIS is the result of what?

A

electron scatter between the photocathode and the MCP

56
Q

The ANVIS is sensitive to the visible spectrum. Additionally, the sensitivity for ANVIS extends ___.

A

well into the near IR range.

57
Q

Incandescent light produces approximately ___as much heat as it does light.

A

five times

58
Q

What are the four operational defects that are an immediate cause for rejecting the ANVIS?

A

ShadingEdge GlowEmission Point(s)Flashing, flickering, or intermittent operation

59
Q

What are the basic components of the ANVIS?

A

Binocular Assembly (two identical monocular)Pivot and adjustment shelfSpring Loaded ball bearingsEyepiece lensObjective lensEye span adjustment knobFore and aft adjustment wheelTilt leverObjective focus RingEyepiece focus Ring

60
Q

What types of batteries are authorized for ANVIS aviation use?

A

1.5V Lithium or Alkaline

61
Q

Put the primary batteries on the wearer’s ___ and the Alternate “zero-time” batteries on the ___.

A

rightleft

62
Q

How should you clean the gold-plated electrical contacts?

A

Clean dirty contacts using a pencil eraser.

63
Q

The optimal sight picture occurs when the optical axis of the monocular is aligned with the operator’s ___, and the eyepiece is at the maximum distance from the eye while still providing the entire FOV

A

visual line of sight

64
Q

When you are satisfied with the alignment for both eyes, use the fore and aft knob to move the ANVIS ___ (___) to compensate for shifts that occur during flight.

A

slightly closer to the eye (about 1/2 turn)

65
Q

Moonlight is the greatest source of natural illumination at night. The moon moves across the sky at ___

A

15 degrees per hour.

66
Q

The sun also has a significant impact on illumination for approx. the first hour after sunset and the first hour before sunrise. This is called ___.

A

sky glow

67
Q

___ provides illumination used by NVGs when the moonlight is insufficient.

A

Starlight

68
Q

The increase in ___ provided by NVDs is the most significant advantage of using such technology.

A

situational awareness.

69
Q

The normal FOV of the human eye is approx. ___

A

120 degrees vertical by 200 degrees lateral

70
Q

The level of ___ and ___ in the ANVIS image depends on the reflective properties, color and texture of the terrain, and objects being viewed.

A

contrast image detail

71
Q

WARNING. Under low flight conditions, the goggles ___ some acuity that they have under high light conditions.

A

lose

72
Q

During aided flight, glare will also drive down the ___, reducing image detail.

A

NVG Gain

73
Q

IR searchlights can be a useful source of artificial illumination during terrain flight operations, however, ____

A

enemy capabilities must be considered prior to their use during tactical missions.

74
Q

Forward Flight. To counteract the limited field of view, aviators should ___. This allows them to build a mental image of the surrounding environment.

A

continually scan throughout the field of regard.

75
Q

Tactical Field Lighting. The inverted “Y” configuration is ___.

A

the most common configuration used by US forces

76
Q

Terrain features should be easily identifiable and ___.

A

unique in shape.

77
Q

What is the biggest consideration that the Command must fully understand when it comes to night terrain flight operations?

A

Crew endurance.

78
Q

Avoid planning routes that head directly into a ___.

A

low rising or setting moon.

79
Q

Formal mission briefings must be conducted sufficiently in advance of the scheduled departure, to allow ___ to resolve identified problems raised during the briefing.

A

time

80
Q

Supplemental lighting is described as ___.

A

lighting that is not part of the aircraft lighting system.

81
Q

What color should supplemental lighting be?

A

Supplemental lighting can be any color, it does not state anywhere that it should be a certain color.

Chegg Decks (24 decks)

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