Introduction

Welcome! This page is meant to help newcomers find their way around the world of night vision.

Therefore it is only fair to say the information below is intended to give an easy overview and general outline of some of the science, terminology, function and peripherals.

While this means an experienced night vision enthusiast might (and probably will) find statements and information to object on we ask these readers for patience on the basis of the intended nature of this page.

What is Night Vision?

What is light?

Not even physicists can actually tell you what light is. If you ask them, they will probably start talking about how light is both a wave and a particle, or neither.

When thinking about light in the context of night vision, it is best to think of it as particles travelling at the speed of light, where each particle has a frequency which defines which color it is.

Besides the visible spectrum of light there is a whole range of other wavelengths, for example the infrared spectrum. Infrared has a lower frequency than visible light. Night vision usually is most sensitive to infrared light, and is often used in light sources when the unaided eye should not be aware of it.

Light will have a varying success of reflecting from surfaces and under night vision reflected light is what you most likely will be relying on when using night vision. That light might originate from the moon, the stars, human civilization (street lights, buildings, airports) or of course illuminators.

What does an analog night vision device do?

At its most simple it allows you to see in the dark, thousands of times brighter than the naked eye can. Obviously there is quite some technical detail going on within the device. Here is a simplified explenation with correlating links to a more in-depth descriptions of how this works.

As mentioned in the previous section light particles travel at different wavelenghts. Night vision recieves an extended range of wavelenghts compared to human eyes and particularly in the infrared spectrum. These wavelenghts enter the device as light particles (scientific term is photons). These photons will be converted to electrons by what is called a photocathode.

Now that the light has been converted to electrons these electrons will enters a microchannel plate or MCP. In the microchannel plate these electrons are amplified (this amplification is dependent on what make and model components you use). After the output of electrons is amplified we need to convert them back to something visible. This is done by a phosphor screen. The electrons react with the phosphor screen which produces photons again, but now in wavelenghts visible to the human eye. So now we can see a produced image. Which is several thousand times brighter than what we’d see with the naked eye.

What does a digital night vision device do.

A digital night vision device will act much like your phone camera, except that it will generally have a larger sensor that has its Infrared filter removed. The whole process after the light hitting the sensor is all digital and the amplification of light is also done digitally. Currently the digital technology is way behind analog options. However these digital devices often do have onboard options to record video without the need of extra attachments and during normal use. Also there are some digital photographic cameras that have had thier infrared filters removed to be more viable for use in astronomy and particularly low-light subject photography.

Applications

History

Whilst night vision devices have been primarely used for avionic applications after its invention, which was around 1929 in Hungary, the earliest adopters of night vision was the German Wehrmacht in the later years of WW2. With the ongoing war and the subsequent cold war, many other countries encountered the devices and so the "arms race" to see in the dark began to ramp up.

But widespread use of night vision would take many years yet. The aviation field has been a strong driving force in the developments and new technological discoveries that later have been adopted for military use.

These days it is employed on a way larger scale and some units across the world are all deployed with night vision. Night vision devices made their way over to hollywood, gaming and other media. With this wider spread of screentime the popularity of these devices is increasing. With technological improvements and widespread use the manufacturers obviously have been producing more and more devices meaning that the second hand market also has seen a steady growth. Both because functional image intensifier tubes that dont deliver enough for military contracts are sold on to distributors as well as complete units are being phased out in favor of newer and even higher performance units.

Applications of night vision

As mentioned before it was primarily used for military operations but the technology is currently implemented in various ways. Helicopter pilots, individual soldiers, tanks, boats, drones and more. For civilian uses we can clearly see a wide enployment in scientific research, astronomy, wildlife observation, hunting and any other recreational use in the dark.

Buying and owning night vision devices

Things to look out for

When starting to look around to get yourself a device there are obviously a few considerations to make. As mentioned this technology goes back almost a 100 years so not all devices are made equal. A good reminder for first time buyers is to consider what they want to do with the device and look into which devices fulfill these criteria sufficiently.

Price is not always the perfect indicator: there are very expensive and modern devices that will outpreform all others while there are also collectors items that are expensive because of their rarity or pristine condition but still do not preform as well as the newest and latest. It’s not uncommon that devices of these two very different natures have similar price-tags.

Besides looking at different specs and models its very important to set realistic expectations on the device you want to get. In the following paragraphs there will be a few points to consider and research before starting your actual search.

One of the first things to consider:

Be aware that some devices need an IR-lamp (illuminator is the technical term) emitting a beam of infrared light to function while others rely solely on available environmental light.

Emitting light is in some cases (for example in more "tactical" implementations) unfavourable but for surveiling your front door or observing animals in the dark without disturbing them it is more than sufficient. If emitting light is not an issue for you, you can look at earlier generations of devices as these will most often be cheaper compared to more advanced technology. An example of device that performs well enough in these situations is first generation digital night vision, often present in entry-level night vision hunting scopes.

If you do not want to emmit light or dont wish to carry a whole set of IR lamps to see your surroundings then you would want to look at generation 2 or later.

These will be more expensive than generation 1 or digital units, depending on their quality and condition.

There is no shame in getting a generation 1 device if this suits your needs, there is no shame in just getting generation 2 instead of the newest: It all depends on your use case and the possibility to spend as much or as little money as needed.

Types of night vision devices

Binocular

Commonly referred to as ”binos” among enthusiasts. This device consists of two seperate image intensifiers (tubes or digital sensors) and because there are two of them they will be able to give users a perception of depth.

Biocular

This device uses one amplifier but will emit a visible view to both eyes. This will help your brain adapt quicker and have a better sense of depth than a monocular. It is sometimes shortened to ”biocs” among ethusiasts.

Monocular

This type of device (referred to as ”mono” in everyday conversations) uses one amplifier and will emit a visible view to one eye. They take longer to adjust to than biocular vision but it has the advantage that one eye will be quicker to adapt to brighter lights where a night vision device is not needed. This is the most common type entering the market these days alongside binoculars. Most likely this is what beginner purchasers get up getting.

Other types

While there are other categories and setup possibilities we will leave these alone for the scope of this introduction.

Mounting Capabilities

There are many different accessories for mounting your nightvision device. It could be for astronomical purposes, for hands free movement or for photography.

Hands free movement

The most common and preffered method for handsfree movement is to mount the NVG to a helmet, head harness or a skullcrusher. To use a helmet or head harness it typically requires that they should come with an adapter plate / shroud. If it has this, it is possible to add a wide array of flip up mounts from brands such as Wilcox or Norotos. Typically you have to combine a flip up mount together with a J-arm, or a binocular bridge.

Taking care of your gear

Care, maintenance, dos & don’ts

- Always remove the battery after use.

- Use only quality lithium batteries, avoid all alkaline batteries.

- Use microfiber cloths with a cleaning solution, camera cleaning pens, or wet lens wipes.

- If your night vision goggle (or NVG) is wet from rain or has been out in sub-zero temp it is recommended to let it dry and/or reach room temp at an even pace before closing it up in its storage case to avoid condensation forming.

- Store your NVG with the lens cap on, in a dark and dry place.

- Turn your device off, or use a protective lens cap when entering a brightly lit area.

- Do not shine lasers (visual or ir-spectrum) into your NVG regardless of wether it is on or off.

- Do not open your NVG housing, and expose its internals, while batteries are plugged in.

- Consult a knowledgeable person before attempting to fix or modify your devices or accessories, there might be far less risky or delicate fixes available.

- It is highly recommended to also get sacrificial lenses to protect the actual lenses of your device.

Legality

Since there are a number of country specific laws applying to night vision technology and their use in civilians hands, it is advisable to follow the following advice:

Always make sure you know what specific laws that apply in your country regarding NVG and their accessories as well as being mindful of following any laws regarding importing and exporting NVGs to and from the countries you want to bring your devices to and from.

Same goes for using night vision in the vicinity of military facilities unannounced, if spotted it could cause alarm and unwanted situations. Be careful, be smart, dont scare people if you can avoid it.

Nomenclature

Below is a list (incomplete and in development) of technical terms, lingo and expressions one will likely encounter wether shopping for night vision devices or talking among enthusiasts:

• FOM: this number will reflect the amplification strength
• SNR: "Signal-to-Noise Ratio": a ratio-number that will indicate the amount of clarity or noise. (higher means the vision will be more clear)
• Resolution: Indicates how much detail a device will show. Expressed in line-pairs per square millimeter (lp/mm2) and as with most specs the higher the number the better the stat.
• Gain: a number referring to how many times the input is multiplied inside device.
• Autogain: the devices capability to automatically adapt its amount of gain. This does not protect the device from brighter sources.
• Autogating: the devices ability to block incomming light, this will protect the device from damage from brighter sources.
• Chickenwire / beehive: a sometimes visible effect of how the MCP is constructed, looks like a chickenwire fence or hexagonal pattern in the display. It is normal, often faint and no cause for worry.
• GEN1/2/3/4..: this will denote the generation of the device. This will give you a general idea of what preformance to expect from a device.
• DOM: Date of manufacturing.
• FOV: ”Field of View”, A number between 1-360 (degrees of a circle) and this number will represent the angle of vision you will get from the device. (Higher number will mean a wider vision)
• Green phosphor (GP): The phosphor layer that converts the electrons back to photons and will create the green shade to the output.
• White phosphor (WP): The phosphor layer that converts the electrons back to photonds and will create a white/grey shade to output.
• HUD: Heads up display, a overlay in the emitted view that can give you various indications (such as if an emitter on the device is on or a battery is low)
• Blemish (blem): dark spots in the device. these occur in the intensifier so are often permanent.
• Black boxing: a method of stimulating the peculiar ”self-healing” process that some (if not many) analog tubes have been found to have.
• Burn: Permanent damage, often visible as a picture in the output, caused by over-exposure to a light source.
• Emission: this is the oposite of a blemish or burn, you will have a permanent bright spot in your view. This is likely to worsen and may lead to tube death sooner than later.
• Ghost / ghosting: temporary bright spot caused by exposure to a very bright source.

• Scintillation (scints): This an effect caused when the device is not getting enough light to amplify, this will look like the same way when you point your phone camera in the dark: random sparks and spots
• Spot: single point imperfection in the image (sometimes defined by zones 1-3 where zone one is the inner 1/3th of the vision and zone 3 the outer layer. this will give you an indication of how disturbing a imperfection will be)
• Peppering: multiple tiny to small imperfections that are scattered around an area just like how it would like if you were to grind pepper on a plate.