Night Vision Defined

[Zarvan]

What is night vision? When we think of night vision we normally visualize images from the iconic green phosphorous image intensifier seen in countless movies and video games. However, we often do not realize that thermal is also an important component of night vision technology as well. Like firearms, night vision is yet just another tool that if used properly can be significantly beneficial to the user. The basic premises behind night vision is rather self explanatory, as a tool that allows the user to see in the dark.

Image Intensifiers
Image intensifiers are used to intensify or amplify ambient light so the user can better see in the dark. In areas with no light, image intensifiers can also utilize infrared light or IR light. IR light is not visible to the human eye. The image intensifiers take photons, convert them to electrons, multiply the electrons, and then convert the electrons back to photons through a phosphor screen in order to produce the image we see.

This graphic provides a visual reference explaining image intensifier technology.
Source: https://tnvc.com/technology/

This system gives us the best opportunity to identify a friend from a foe.

Notice even when the subject is somewhat backlit identification is extremely difficult under these lighting conditions.

Here we can not only identify the individual but we can also identify a pistol in his gloved hand.

Not only can we see that he is carrying keys and an envelope but we can easily see facial features and get a positive ID.

While the image is set at a single focus point in which objects farther or closer are not in focus, the intensifiers can be manually adjusted for focus at varying distances. Since image intensifiers are simply utilizing light, barriers such as a windshield or thin glass do not present much more of an issue for identification than such barriers would make during the day. For threat identification and navigation image intensifiers are extremely helpful.

Thermal Technology
Thermal technology utilizes thermal-infrared waves. These waves make up the largest portion of the infrared spectrum ranging from 3 to 30 microns. As opposed to the near and mid infrared sections thermalinfrared is emitted from the source rather than reflected. IR energy is released in varying amounts based on the amount of heat radiating from the source.

Above we see how the IR energy is converted to an image that allows us to visually discern variations in temperature. Source: https://www.atncorp.com/howthermalimagingworks

Using thermal technology the user can easily identify differences in heat and therefore can easily see the outline of a human or creature. This helps the user quickly find a warm body against a cooler background. However, facial features can not be easily identified and threat ID is difficult. Thermal units also do not perform well with barriers.

Notice that the thermal unit definitely helps identify the location of a heat source but facial features are not recognizable.
Source: https://www.midwayusa.com/product/1...x-19mm-640×480-stadiametric-rangefinder-black

Using a thermal unit you can not obtain a temperature difference through a window of a vehicle or the wall of a building. Unlike image intensifiers, thermal units can be used in any lighting condition. Thermal units also require no light to function. This eliminates problems with a light source visible to opposition possessing an image intensification device.

Conclusion
Many often do not think to combine the two technologies. While expensive, using a thermal unit to scan an area and then an image intensifier to identify the heat signature can provide a significant force multiplier. Night vision is nothing more than a tool and learning which tools combine to produce the best results is extremely beneficial. Newer units like the PSQ-36 now integrate both thermal and image intensification technology into a single unit.

The PSQ-36 allows standard thermal overlay as seen in this picture as well as an outline setting to trace the outside of the heat source. Source: https://tnvc.com/shop/l-3-anpsq-36-fgs/




http://www.thefirearmblog.com/blog/2018/05/31/night-vision-defined/

 

[Zarvan]

Natural Night Vision

Night vision goggles are a great tool but are not always practical. Sometimes we simply have to utilize our natural night vision. In order to get the most out of our natural night vision we should understand how our eyes see at night.

While dual tube night vision is very beneficial it is not always practical. Photo Credit: @sweetmarlena87

Anatomy and Functions
Our eyes see in a vast span of lighting conditions, from a bright sunny day to the darkest night. This is accomplished by different parts of the eye working together. These parts are the pupil, rods and cone cells, and photopigments. The pupil is responsible for how much light is allowed into the eye. Like the aperture on a camera it grows and shrinks to allow the proper amount of light. This can be seen when someone is exposed to a bright light and their pupil quickly shrinks.

As the pupil grows or shrinks it increases or decreases the amount of light allowed into the eye.
Source: https://www.allaboutvision.com/resources/anatomy.htm

The rod and cone cells determine the color and perceived detail. With enough light cone cells pick up color and fine details for the image we see. In the dark rod cells allow us to see better but provide a black and white image with poor detail.

The rod and cone cells determine the color and perceived detail.
Source: https://askabiologist.asu.edu/rods-and-cones

Reaction to Light
Photopigments are light-sensitive chemicals in both rods and cones. Light causes a chemical reaction with the photopigments that convert the light to electrical energy our brain can interpret. Rhodopsin is the photopigment that enables night vision. However, it is very light sensitive and will decompose when exposed to bright light sources. Some animals that need to see in the dark have many more rods than a human eye.

Light is allowed into the eye through the pupil and is converted to electricity by the rod and cone cells which is a visual signal sent to the brain.
Source: https://askabiologist.asu.edu/rods-and-cones

If decomposed, rhodopsin can be regenerated in darkness as the eye again attempts to adjust to its surroundings. It can take over half an hour for the human eye to fully regenerate Rhodopsin and have peak night vision. This is in sharp contrast to cones that only take 5 to 7 minutes to attain maximum sensitivity.

The eye being set up in this fashion is extremely beneficial. The pupil allows in a regulated amount of lightand the discs containing rhodopsin or photopsin are continually recycled. This ensures your visual system remains healthy. The discs are next to the epithelial cells (retinal pigmented epithelium: RPE) in the back of the eye. This makes it so that parts of the RPE are easily carried away. RPE is also able to take in scattered light. This clarifies your vision for a much cleaner image. Light can have damaging effects on the eye and having the pupil limiting light with the rods and cones at the back of the eye helps to protect them from damaging amounts of light.

Why is this Important?
It is no secret that a large portion of crime happens under the cover of darkness. While we prefer to train when it is 70 degrees and sunny, we must realize that it is likely we could get into an engagement in the dark. If we understand the eye and how it functions we can better prepare ourselves and allow ourselves to see what we need to see.

One tip that helps us protect our night vision is to wear sunglasses during the day. A few hours of bright exposure can increase the time it takes the eye to adjust to darkness by as much as 10 minutes. Wearing sun glasses will reduce the brightness over extended periods and help protect your night vision.

Tinted eye protection is a great way to protect your night vision as well. Photo Credit: @sweetmarlena87

Before going into a low light environment, wearing red lenses for 20-30 minutes will help improve night vision as the rods do not react to the color red. This is also why there are often red filters used on militarylights to allow for a small amount of light that is not easily visible at a distance. Lowering the brightness on electronic devices also helps reduces the amount the eye has to adjust. Also realize the effect of light on an aggressor.

Situational Awareness
By maximizing our natural night vision we are enabling ourselves to have better situational awareness and may be able to simply avoid an incident all together. However, when necessary light can also be used as a positive tool just light during transitions between white and IR light with NVGs.

Seeing what you need to see is important when assessing unknowns. Photo Credit: @sweetmarlena87

Light will also negatively impact the rods in your opponent’s eyes and can help provide you with an advantage. Carrying a quality light with a good hot spot will also help with controlling an unknown or a known threat.

Putting the hot spot of the light in the eyes of the unknown and using the spill to assess what is in their hands can be an effective use of a light. Photo Credit: @sweetmarlena87

What’s Up Doc?
How do carrots affect your eyes? From what grandma told you growing up you probably thought you would get super vision powers from eating them. Photoreceptors contain a pigment molecule called retinal. Light enters the eye in the form of photons which is absorbed by retinal. Through this process retinal is destroyed. Vitamin A is needed to regenerate retinal. While carrots provide vitamin A and this is healthy for your eyes, getting vitamin A from carrots or other foods will help with eye health but will not improve vision clarity.

Source: http://www.johnnyseeds.com/vegetabl.../hercules-pelleted-f1-carrot-seed-2735JP.html

Conclusion
We often don’t think of getting enough vitamin A, not smoking, or wearing sunglasses outdoors as a tactical decision. However, each of these factors help improve eye health and together will increase our night vision and give us an advantage.

A normal pocket dump does not contain night vision. Whether running aided or natural night vision, understanding how the eye works and taking small steps to maximize ocular health will provide you with an advantage. Photo Credit: @sweetmarlena87











http://www.thefirearmblog.com/blog/2018/05/31/natural-night-vision/

 

[Zarvan]

NVG Head Harness

Hands Free Systems
Night vision is an incredible tool, but to utilize it to its full potential it often must be able to be used in a handsfree manner. Everyone sees the “tacticool” helmet systems worn with NODs by all the tier 1 units. These are effective, but not all users need ballistic protection, strobes, or have the extra cash to devote to a helmet setup. Bump helmets are a good compromise, but again these are still relatively expensive and too bulky for some uses. Finally, many have seen and used a NVG head harness like the standard “skull crusher” that comes in the kit included with most PVS-14 units. While cheap, this system is so uncomfortable that it really is ineffective. During nearly any form of movement as the night vision bounces around and away from the eye.

Standard skull crusher head unit. Notice how the unit uses solid material from the mount back to the user’s ear.
Source: http://www.nightoptics.com/product/A3144268.htm

Compact Package
For those wanting a light, compact, and concealable retention system that would allow for night vision to be readily mounted, few options exist on the market. Will’s Optics will be releasing a new Ultra Lightweight Nylon NVG Head Harness that was designed for this exact purpose.

The head unit works well even with light dual tube systems.

First we notice that there is not a hard skeletal structure like skull crushers, so the unit could easily fold down on itself and be stowed in a hoodie or jacket pocket.

The head set conveniently fits in hoody or jacket pockets when not in use.

When folded up, the head harness fits into the palm of your hand.

Adjustable
As heads can vary in size, the head unit has numerous adjustments that can be set to the individuals preferences.

The numerous adjustments really help with the fit of the system.

The primary complaint with the skull crusher was how uncomfortable it was to wear. With the hard skeletal structure, the old skull crusher was bulky and resulted in numerous hotspots around the head and forehead. This was improved on by adding a thin padding beneath the mount where the weight of the monocular or goggle would press down on the forehead.

This padding is extremely important to the comfort of the head harness when worn.

The straps were made to a width that would still remain low profile but would be wide enough to be comfortable with the added weight of the goggles. Wraps are placed near the head size adjustments and not only help retain the excess material, but double as cable routing and management systems.

Loops are found on each of the adjustments to retain the extra material and can be used for battery or com cable routing.

Accessory Mount
On the back of the head unit there is also a small area with loop Velcro. While the design was to eliminate bulk, some users may still require a small amount of support equipment. This area is small due to the nature of the system, but is large enough to attach a battery pack or IFF patch.

On the back is a small velcro section for battery packs and IFF patches.

Personally for extended uses I would prefer a bump or ballistic helmet, but for short uses Due to their not being a secondary means of retention I have decided not to use a battery pack with the system for fear of losing or damaging my battery pack. However, this system is more for concealment and not extended use. Even in cold weather conditions, the battery life provided by a new lithium AA exceeds my needs for short uses.

Like anything in the night vision realm the price is not cheap, but you get what you pay for. This head harness retails for $295 and is available here.

Final Thoughts
This system does not replace a helmet but definitely serves a different purpose. While far more comfortable than a skull crusher, this unit still is uncomfortable for extended use. A PVS-31A was used for testing and worked, however a PVS-14 or MOD3 would be more concealable and would reduce weight. Like any other tool this is for a niche use.

Personally for extended uses requiring a battery pack I would prefer a bump or ballistic helmet, but for short uses a battery pack would not be necessary. Their is not a secondary means of retention, and losing or damaging a battery pack can be costly. However, this system is more for concealment and not extended use. Even in cold weather conditions, the battery life provided by the onboard battery should be sufficient for the short uses I would utilize this head harness for.

Having the ability to see at night is a game changer, but for many carrying a helmet with dual tubes is not practical. For those worried about maintaining a lower profile and reducing bulk this head harness does the job well.

http://www.thefirearmblog.com/blog/2018/05/31/nvg-head-harness/

@Path-Finder @Arsalan @Horus

 

[Zarvan]