NVG NOMENCLATURE, CHARACTERISTICS, LIMITATIONS, AND OPERATIONS Flashcards
Describe how light passes through the ANVIS.
OPMPFE
Other People’s Money Pays For Everything
Objective Lens (inverts image, minus blue filter)
Photocathode (changes photons to electrons)
Microchannel Plate (multiplies electrons)
Phospher Screen (electrons to protons, creates the lighted image)
Fiber Optic Inverter (inverts the image)
Eyepiece Lens (allows the eye to see the image)
What is Automatic Brightness Protection (ABC)?
ABC automatically adjusts microchannel plate (MCP) voltage to maintain image brightness at preset levels by controlling the amount of electrons that exit the MCP. ABC is to protect the wearers vision, not to protect the goggles.
What is Bright Source Protection (BSP)?
Reduces the voltage to the photocathode when exposed to bright light sources. This protects the goggles from damage and enhances its life (however, it lowers resolution). Exposure to bright light sources could result in damage to the photocathode, MCP, or the operator’s eye.
What is an operational defect?
Defects that relate to the reliability of the image intensifier and are an indication of instability. An operational defect is an immediate cause for rejection.
What are the operational defects?
FESE
Flashing, Flickering, or Intermittent Operation
Edge Glow
Shading
Emission Point
Describe Flashing, Flickering or Intermittent Operation.
Light appears to flicker or flash. Can be in either one or both monoculars.
Describe Edge Glow.
A bright area in the outer portion of the viewing area (could be caused by a series of emission points). Check by covering the light entering from the objective lens. If it remains, it is edge glow.
Describe Shading.
You will not see a fully circular image, regardless of the adjustment. Begins at the edge and works inward. There will be a high contract area with a distinct line of demarcation.
Describe an Emission Point.
A steady or fluctuating pinpoint of bright light in the image area and does not go away when all light is blocked from the OBJ lens.
What is a cosmetic blemish?
A manufacturing imperfection / maintenance imperfection that does not affect image intensifier reliability. Not normally a cause for rejection unless they interfere with ability to perform the mission.
What are the cosmetic blemishes?
IF I C BOB
Image Distortion
Fixed Pattern Noise
Image Disparity
Chicken Wire
Bright Spots
Output Brightness Variation
Black Spots
Describe Image Distortion.
Evidenced by vertical objects (poles / trees) appearing to bend when you move your head vertically or horizontally. Ground surfaces may appear to swell or sink as well.
Explain Fixed Pattern Noise.
AKA Honeycomb
Faint hexagonal pattern throughout the viewing area that most often occurs at highlight levels.
Explain Image Disparity.
Difference in brightness between the two image intensifier assemblies within the same binocular.
Explain Chicken Wire.
An irregular pattern of dark thin lines in the field of view either throughout the image or in parts of the image. Under worst conditions, these lines will form hexagonal shaped lines (think of it as the beginning of honeycomb)
Explain Bright Spots.
These are SIGNAL induced - a bright spot is a small bright area that may flicker or remain constant.
Explain Output Brightness Variation.
Evidenced by Areas of varying brightness in or across the image area. DO NOT CONFUSE WITH SHADING. There are no distinct lines of demarcation
Explain Black Spots.
These are blemishes in the image intensifier or dirt, hair or debris between the lenses.
What 6 things do we use to talk about the characteristics of the NVGs?
DIAL VP
Definition
Intensification
Acuity
Limited field of view
Voltage low indicator
Power Supply
What is the definition of the NVGs?
Helmet mounted binocular vision, passive light intensifier device that allows pilots to fly at terrain flight altitudes during low ambient light levels.
What is the intensification of the NVGs?
2000 - 3000 times
What is the visual acuity of the NVGs?
Best is 20/25 when looking through the center of the tubes. At the periphery, the acuity can decrease to 20/70
What is the field of view of the NVGs with a proper OSAP?
40° FOV
How do you know if you have low battery (voltage) on the NVGs?
A blinking red light at the bottom of the helmet mount (comes on at approximately 2.2 - 2.4 VDC).
How much time is remaining on the battery pack if the low voltage indicator comes on?
Approximately 30 minutes.
What are the 3 sources of power available for the NVGs?
1) Battery pack
2) Aircraft via power converter
3) COPS (Clip On Power Source)
What is the breakaway force for the NVGs?
10-15 Gs
What are the considerations for using NVGs?
CALM WWAD SOS
Color Discrimination
Airspeed and Groundspeed Limits
Lights
Magnification
Weather
Weapons
Aircraft Lighting
Depth Perception and Distance Estimation
Scanning Techniques
Obstruction Detection
Spatial Disorientation
Explain the NVG consideration - Color Discrimination
Color Discrimination is absent under NVGs Monochromatic (single color): green hue due to type of phosphor used Chromatic Adaptation: green hue may cause crewmembers to experience a pink, brown, or purple after image when they remove NVGs. (this is normal).
Explain the NVG consideration - Airspeed and Groundspeed Limits
NEVER OUT FLY YOUR VISIBILITY / THE CAPABILITY OF THE NVG’s. Consider:
- Type, age, and condition of NVGs
- Cleanliness of aircraft windscreen or sensor window
- Moisture content in the air (humidity)
- Individual and collective proficiency and capability
- Weather Conditions (fog, rain, low clouds, dust) and ambient light.
Explain the NVG consideration - Lights
PET
Performance Relations - proportional to ambient light available (high ambient light = high visual acuity and potential fixed pattern noise, honeycomb, chicken wire) / (low ambient light = low visual acuity and potential scintillation)
Effects of Bright Light: ABC (voltage to the micro-Channel plate reduced) and BSP (voltage to the Photo Cathode)
Tunnel Vision: landing light, searchlight or IR - avoid concentrating on the area illuminated by the light.
Explain the NVG consideration - Magnification
NVGs do not magnify an image; they enhance the illumination of an object. Magnification is 1:1 (meaning there is none).
Explain the NVG consideration - Weather
Aviators may fail to detect entry into or presence of IMC because we can see through slight obscurations (fog, rain, haze, dust, smoke) Watch for:
- HALOs: artificial light may produce brighter appearing halos around the source
- Scintillation: (video noise)
- Loss of celestial lights / moon
Explain the NVG consideration - Weapons
While firing, aircrews may briefly lose sight of the target - cause for concern for the impact area. The recovery from bright flash illumination is more rapid with NVGs than unaided.
Explain the NVG consideration - Aircraft Lighting
ANVIS-6 designed to operate with blue - green cockpit lighting Red Cockpit lighting is not compatible and NOT AUTHORIZED External aircraft lighting should be turned off depending on the operation.
Explain the NVG consideration - Depth Perception and Distance Estimation
Depth perception in a given situation is dependent upon:
- Available light
- Type and quality of NVGs
- Degree of contrast in the FOV
- User experience
Explain the NVG consideration - Scanning Techniques
Aviators head and eyes must rotate slowly and continuously to view an entire area.
Explain the NVG consideration - Obstruction Detection
Obstructions w/ poor reflective surfaces (wires, small tree limbs) are difficult to detect. Best way to find wires is to look for the support structures.
Explain the NVG consideration - Spatial Disorientation
Maneuvers requiring large bank angles or rapid attitude changes tend to induce spatial disorientation. An aviator should avoid making drastic changes in attitude / bank angles and use proper scanning and viewing techniques.
