Night Vision Devices Flashcards
Thats the function of the cornea?
Protect the eye
What is the iris?
The colored membrane around the pupil
Function of the iris
Adjusts the pupil size to allow light into the eye
What is the function of the lens?
- To focus light on retina
- Hardens with age
What is the retina?
The light sensitive part of the eye
What component of the eye adjusts the pupil size to allow light into the eye?
Iris
Cones work best in ____.
Daylight - 50% illumination and up
Rods work best in _____.
Low light - 0% illumination and up
Cones have a 1:_____ ratio.
1
Rods have a 1:_____ ratio
Thousands
What is the Fovea Centralis and what are its characteristics?
- Contains only cone cells
- 15* off center
- Direct or central vision
- 2 mm diameter
- 85% of visual information comes from Fovea
What is the optic disc?
Where the optic nerve enters the retina
- Called the day blind spot
What does the Parafovea contain? (Rods/cones)
Both rods and cones
Which type of vision is characterized by lack of color perception and requires off center viewing?
Scotopic
What is Rhodopsin and how long time does it take to build up?
- “visual purple”
- Requires buildup to see at night
- 30-45 minutes to build up
- Bleached by bright light
How long times does it take to readapt after exposure to bright light?
5-45 min
What does the Peripheral regin contain? (Rods/cones)
Rods
Scotopic vision is when:
Light environment are below 50%
Mesopic vision is when:
Light is between 50% and daylight
Photopic is when:
Its daylight
How to preserve your eyes?
- Dark sunglasses with a neutral grey tint
- Light transmission of 15% or less
- Authorized Protective Eyewear List
How to make eyes healthy?
Vitamin A in the form of Milk, Cheese, Carrots, Green vegetable, Liver, Fish
- Multivitamin
If there is bright light, the area around it will what?
Blacken out
How to avoid muzzle flashes and tracers?
- Close or cover 1 eye
- Limit burst length
- Turn away
Cockpit illumination should be set to:
Lowest easily readable level
Night blind spot covers ____ - ____ degrees?
5-10 degrees
What is the cause of the day blind spot?
Optic nerve
How do we compensate for day blind spot?
Viewing with binocular vision
What is the “Field of Regard”
What you can see in a given helicopter
3 scanning techniques
- Stop turn technique
- Ten degree circular overlap
- Off center viewing
Why is the circular overlap 10*?
To ensure a cover area larger than the night blind spot
What are the Monocular cues?
- GRAM*
- Geometric perspective
- Retinal image size
- Aerial Perspective
- Motion parallax
Types of Geometric perspective:
- LAV*
- Linear perspective
- Apparent foreshortening
- Vertical Position in the field
Types of Retinal image size:
- KITO*
- Known size of objects
- Increasing or decreasing size of objects
- Terrestrial association
- Overlapping contours
Types pf Areal perspective:
- FLaP*
- Fading color or shades
- Loss of detail or texture
- Position of light source and direction of shadow
What is a laser?
Intense, narrow beam of light
NOHD is short for:
Nominal Ocular Hazard Distance
- The minimum distance where a laser is considered to be eye safe
Class 1 lasers are:
Cheap lasers such as cd players
Class 2 lasers are:
Lazer pointer and comercial scanners
- Caution do not stare directly into
Class 3a ( low power) lasers are:
Aircrew laser pointer
- Potential hazardous if the direct of reflected beam is viewed by the direct eye
Class 3b (high power) lasers are:
High power laser sights for firearms
Class 4 lasers are:
Laser range finders or target designator
- Capable of producing diffuse reflection, fire and skin hazards
Class 5 lasers are:
Anti missile/ship defense
- Capable of burning objects directly exposed to energy
safety wise class 3 and 4 lasers can be compared to:
Firearms
What precautions must aviators take to ensure laser safety?
- Threat a laser like a loaded weapon to avoid injury
- Do not point any laser directly at other people
- Do not look into any infared laser beam
- Do not point any laser beam at mirror-like surfaces
- Laser eye protection should be worn when operating, Maintaining, servicing, or testing the ALP in high power mode
- Never view any laser through magnifying optics without appropriate safety filters
- Only operate lasers inside the cockpit of an aircraft in accordance with the appropriate AWR and local procedures
How much exposure time is required to cause miosis?
Dependent on amount of exposure
What are the visual illusions?
F-ire F-ire F-ire CRASH CARS
- Flicker vertigo
- False horizons
- Fascination/fixation
- Confusion w/ground lights
- Relative motion
- Altered planes of reference
- Size-Distance
- Height-depth perception
- Crater illusion
- Autokinesis
- Reversible perspective
- Structural
What tool can help maintain a/c control when hovering over contrast or disorienting surface?
HUD
What is White Hot?
The hotter the whiter and is used for target acquisition
What is the thermal systems ability to detect small differences in temperature called?
Minimum resolvable temperature (MRT)
Which polary setting is best for selecting hot spots?
White hot
Which lens has the anti blue coating?
Objective lens
The Field of view with NVGs are _____ degrees
40
Best NVG Visual acuity:
20/25
Worst NVG visual acuity:
20/70
Best unaided Visual acuity (at night):
20/200
Operational deficiencies
- Shading
- Emission points
- Edge glow
- Flashing/flickering and intermittent operation
Types of natural light at night:
- Moonlight (moves across the sky at 15 degrees/h)
- Starlight
- Sunlight
Visual illusion and Spatial D is more like to occur at night due to:
- Inexperience
- Degraded visual acuity
- Limited FOV
- High task loading
- Fatigue
In daytime you can use color vision and high level of visual acuity, but at night time you must rely on:
- Size
- shape
- contrast
- reflectivity
What factors increase the likelihood of experience visual illusion or Spatial D?
- Inexperience
- Degraded visual acuity
- Limited FOV
- High task loading
- Fatigue
The level of contrast at night depends on?
- Color and texture
- Level and type of ambient light
- Reflectivity
Types of terrain we can fly in:
- Urban
- Vegetated/rolling terrain (the best to fly NVG in)
- Mountains
- Desert
- Arctic/snow
- Over Water
WARNING: Exercise extreme caution when flying from ____ ambient light conditions to ____ ambient light conditions.
Under _____ light conditions the google loose some acuity that they have under _____ light conditions.
Flying from _____ to ____ light conditions quickly reduces the sharpness and definition of terrain images.
Hight , Low
Low , High
High , Low
High moon elevation provides:
More ambient light at a high elevation than at low elevation
Low moon elevation can be beneficial by:
Making minor terrain features more apparent due to the shadows that form.
- The shadows can also get to large and degrade scene detail
If ambient light levels unexpectedly decrease what indications may be present?
- Scintillation
- Increase in halo intensity
- Loss of celestial light
- Loss of ground light
Degraded visual environment includes:
- Clouds
- Fog
- Rain
- Dust
- Snow
Battlefield light sources can negatively impact the ANVIS image due to what power supply functions being activated?
- Automatic rightness control (ABC)
- Bright source protection (BSP)
(Both of the functions there are)
___ is the best tactical field lighting for a LZ
Inverted Y
What about night flight does 95-1 say?
You need a flashlight
General considerations regarding NVG mission planning:
Psychological and physiological stress
- Navigation
- Radio communication
- Battlefield light source
- Obstructions
- En route data
- Altitude changes
- Meteorology
The commanders considerations are:
- Crew endurance
- A/C maintenance
- Safety
- Environment
- Planning cell
