Taking Care of your NVG
How should you use a Night Vision Device without destroying it? People are overly cautious and don’t get the full potential out of their device. After all, for many, buying a NVD is investing in a NVD. And when you invest you want a return. That return can be maximized by knowing the limits of the device.
Note: This guide applies to military grade Gen 2+ and Gen 3 devices such as the PVS-14 or DTNVS.
You can basically divide it into 3 categories: Use, Maintenance and Storage.
Use
First of all, don’t turn it on in daylight without the daylight cap (pinhole cap) on the objective. Without it, using your device during the day is going to significantly decrease the lifetime of your image intensifier tube. Follow the manufacturer’s instructions for daytime use. When exposed to direct sunlight, permanent damage can occur. Even when your device is switched off, direct sunlight or other bright lights can permanently damage your tube. Always cover your NVG when not in use.
Rule of thumb: once it is properly dusk, you can take the cap off. As long as it still feels like daylight, leave it on. Autogated tubes are able to handle even more light. If you are going to mostly use your device in well-lit urban environments, autogated tubes are highly recommended. Not only does it preserve the tube’s lifetime in highlight environments, but also increases resolution. Autogating does not make a tube immune to very bright light, though.
Avoid direct exposure to bright light sources, such as car lights, lasers, explosions, fires. If you do happen to get exposed, turn the device away right away. Short exposure is far less dangerous than long exposure, and a quick reflex will save your tube in most cases. Lasers are the exception: a direct hit can damage the tube (and your eye) instantly.
Make sure you get that ocular diopter focus right — many people seem to struggle with that. If you don’t get it correctly focused, it is going to be like wearing a stranger’s glasses. To get a good focus, look for a small light source far in the distance (stars work well). Adjust your objective lens on that light source. After that, go back to your ocular lens and turn it all the way counterclockwise. Then slowly turn clockwise until the light source is perfectly in focus again — immediately stop there.
Use your device when it’s raining. Military grade devices are built for bad weather, so rain is no excuse to not use your NVD. How waterproof a device really is depends on the model and the condition of its seals, so check the specs before you take it into heavy rain or water. The housings are tough, just don’t smash them onto concrete.
Maintenance
Keep your lenses clean — both objective and ocular. Use one-time-use optical cloth only and blow away any sand or loose particles first. Don’t use regular cloth or even your shirt; that will scratch and damage the anti-reflective coating on your lenses. Use a brush to get rid of any dirt on the housing; you can also use water.
Don’t open your device. It’s filled with nitrogen gas to prevent corrosion and internal fogging on the lenses. It preserves the electronics by preventing oxidation. The military usually refills its devices every 6 months with nitrogen, but that is not really needed for civilian users.
Storage
Very important: store it without a battery installed. We all know that when batteries get older, they leak. Triple-check and make sure your device is turned off after usage. If left on and exposed to light, the image is going to get burned into your tube and permanently damage it. Store it in a dry place at room temperature, ideally in its case with a desiccant pack, and away from direct sunlight.