Methods for night vision adaption

Night Considerations Agenda Methods for night vision adaption. Ways to maintain night vision. Techniques for observing objects at night. Techniques for engaging targets at night. The Human Eye Functions like a camera Receives, focuses, organizes light Three basic parts of the eye: Pupils Lenses Retina Rods Cones Disection of eye Pupils Smaller in bright light Larger in dim light and in dangerous situations Decreased image sharpness in low light / darkness If you need even minor corrective lenses, you must wear your glasses in dark Lenses Focuses images on retina Incorrectly focuses too close at night Works better under blue green light than red lights Objects illuminated by red light light require more focusing power than those lighted by blue-green light Retina: (Rods and Cones) Visual reception portion of the eye: Rods and Cones: Cones (fast reactors) Sharp vision/depth perception Color vision and day vision Rods (slower reactors) Reduced visual acuity (20/200) No color – shades of gray Factors Affecting Night Vision Fatigue Lack of Oxygen Long exposure to sunlight Heavy Smoking Drugs Headaches Illness Alcohol (48 hours) Improper Diet Night Vision Adaption The time required for the eye to shift from using the cones to the rods Slow process No shortcuts Night Vision Adaptation Method #1 Remain in an area of darkness for 30 minutes Indoors or Outdoors Not able to perform tasks while acquiring Night Vision Adaptation Method #2 Remain in darkened area under low intensity red light 20 min 10 min in total darkness Produces almost complete night vision adaption Allows for performance of tasks Maintaining Night Vision Minimize all ambient lighting Close one eye when you know you will be exposed to bright light source Small arms fire of short duration will not seriously reduce dark adaptation Rocket blast or flare for more than1 sec may cause temporary TOTAL loss of night vision Observation Technique Off-Center Vision Pay attention to an object without looking directly at it. Very effective at night Maximizes use of the rods Movement easily detected with peripheral vision Never look directly at object 6-10 degrees away from the object Observation Technique Figure 8 Scanning Short, abrupt, irregular eye movement around an area Move eyes in figure 8 pattern Pause for a few seconds at each point of observation Rest eyes frequently 4-10 Seconds Most effective in prone position Creates a silhouetted view. Illumination Ground and Air Ambient/artificial light affects Depth perception Apparent target distance / size Light from close behind /between Makes objects appear closer Light from a distance beyond Makes objects appear more distant Air Illumination Fixed objects appear to move. Night Operations: Advantages Increases chance of surprise Technology Enables soldiers to ID, engage, and destroy targets Direct Fire ranges are reduced Increases lethality Can engage before being detected Night Operations: Disadvantages Very difficult C2 Grouping/Bunching up Disorientation Target ID difficult “shoot anything that moves” Fratricide increases Urban Effects on Night Vision Devices White Out Street Lights, headlights, etc. Fires/dust limit thermal imagers Reflective Surfaces Induce errors in laser range finders & target designators Dust, smoke, fog Limit target acquisition w/ NVDs Movement Considerations (1 of 2) Control your noise Stop and listen for enemy noise Remove any distorting headgear Smell Touch - operate gear by feel Movement Considerations (1 of 2) Concealment Don’t get careless because it’s dark – use the shadows Observing – search the horizon Low power optics work Acquiring Targets Keep head above your sights Increases field of view Improves sharpness of detail Keep both eyes open Increases field of view Improves depth perception Engaging Targets Tendency to Shoot High Difficulty picking up front sights Muzzles elevated too high Muzzle Flash Technique Use flash to align sights No Light Shooting Technique Mount flashlight The Night Combat Mindset Affects all your senses Higher stress Must eliminate hesitation/ fear Focus actions to make well aimed shots Attention is easily diverted Summary Gain/maintain night vision with knowledge of factors that control it. Improve capability with use of effective observation techniques and illumination. Acquire/engage urban targets in darkness with use of NVDs and dedicated training. In an urban environment, most of the high-risk work is done in some type of reduced light. Therefore, in order to hit our targets we must deal with the hazards and physical limitations of darkness and low light conditions. Normally, we want to use night vision devices to see objects or parts of objects that would otherwise be too small to see in reduced light. On the other hand, we can help ourselves by learning as much as we can about ways to optimize our unaided night vision. 1. Since most of a person’s sensory input is obtained from the visual system, we can increase our effectiveness with an understanding of the system’s basics. 2. The Human Eye functions like a camera. It receives, focuses, and organizes light in order to process vision. The three major parts of the eye that affect night vision are: a. Pupils b. Lenses c. Retina, made up of: i. Rods Cones 1. The pupils of your eye become smaller under bright lighting conditions and larger during lowered levels of illumination. The pupils also become larger during times of general excitement such as facing dangerous situations. 2. Increased pupil diameter decreases sharpness of images in the eye’s optics. For example, soldiers with refractive errors may not need to wear spectacles during daylight due to a relatively small pupil size. At night, however, with diminished lighting intensity, the pupil is larger and vision becomes unacceptably blurred unless corrective lenses are used. So, if you are not wearing your glasses at night, you seriously decrease your vision—and much of your depth perception. 1. The lens of your eye focuses (on the retina) the image that you are viewing. a. It incorrectly focuses too close at night or in reduced visibility. b. Works better in under blue green lights than red lights. Objects illuminated by red lights require more focusing power than objects illuminated with blue-green lights. Your retina is the visual receptive portion of the eye. Made up of rods and cones, it has a central area and a peripheral area. The central area is made up of cones, while the peripheral retina is composed mainly of rods. 1. Major functions of cone cells are: a. Fast acting—very quick response to visual stimulus. b. Sharp visual acuity. i. 20/15 vision. c. Responsible for color vision. d. Gives you very accurate depth perception. e. Sensitive from sunlight down to full moonlight. f. Responsible for night blind spot. 2. Major functions of rod cells are: a. Slower reactors b. Reduced visual acuity c. 20/200 at best d. No color perception e. Just black and white, with shades of gray Sensitive in reduced light down to individual photons. Once night vision is acquired, it is essential to maintain it in order to operate effectively. This can be accomplished by the following actions: 1. Adjust your ambient lighting as low as possible, consistent with the mission. 2. Minimize use of exterior lights (e.g., vehicle headlights). 3. Close one eye when you know you will be exposed to a bright light source. a. Night vision is rapidly destroyed by exposure to normal or bright light. b. Small arms fire of short duration will not reduce dark adaptation appreciably; However, rocket fire, machine gun fire or exposure to a flash, flare or searchlight beam for longer than one second in duration may cause temporary or total loss of night vision. 1. Ambient light is the existing, or surrounding light. Its source can be either natural or artificial. It comes from things such as the sun, moon, and stars. Ambient light can also come from streetlights, building lights (windows) spotlights, flares, explosions, etc. a. It is affected by the time of the year, weather, terrain, and vegetation. b. Artificial Light is produced by other than natural means. It is categorized into either ground-sourced or air-sourced. 2. Both natural and artificial light affect depth perception, apparent target distance and size, and night vision. a. If a light source comes from close behind or between objects, it will make the object appear closer. i. Shadows will be taller. b. If a light source comes from a considerable distance beyond the object, it will make the object appear farther away. i. Shadows will be shorter. c. If a light source comes from the air, it will create moving shadows, making stationary objects appear to be moving. 1. Sounds. a. Your ears can provide you and your adversary with information. It is necessary to exercise every precaution to prevent the enemy from hearing you or vice versa. b. When moving at night, stop and listen. c. Headgear that distorts sound should be removed. d. Most important, be aware that because there is less ambient noise at night, sound is a lot more important than it is in the daytime. 2. Smell. a. Use your nose as well as your ears to compensate for lack of vision. b. A sense of smell can detect unusual or distinct types of activities. It is the strongest of all human senses. 3. Touch. a. Learn to operate and adjust equipment at night by touch. Using your hands instead of your eyes will save time and lives. b. Training is key to develop your muscle memory. 4. Concealment. a. This is provided by complete darkness at night. b. Apply the same methods you would for daylight, but do not get careless because it is dark. c. Use the Shadows. 5. Observing. a. Search the horizon. Low power optics can increase your range of vision and aid in movement. Operations at night are essential to achieving success in all environments, especially the urban one. It is up to every individual soldier though, to practice common sense steps while operating at night in the urban environment. If this occurs and night vision, mental preparedness, and low light level shooting techniques are employed, night operations can and will be successful.