Articulation VS. Fixed Bridge
One of our main goals at Licentia Arms is to educate our customers and help them make an informed purchasing decision. While helping customers select their night vision one of the most common questions is, “should I go articulation or fixed bridge?”
To answer this question, we must first understand the difference between the two. Fixed bridge binocular night vision is a housing where the optical pods are attached to a fixed bridge and do not rotate out. On fixed bridge systems the inter pupillary adjustment (the distance of the pods from each other to properly cover the eyes) is adjusted with thumb screw to move the pods in either direction on the fixed bridge. The most popular example of this is the RNVG (Ruggedized Night Vision Goggle).
Articulating night vision goggles still have two optical pods that cover both eyes; however they are adjusted very differently. Articulating goggles do just that, Articulate! Articulation is where the optical pods pivot on the bridge both out and in. This is for two reasons… first to give the user adjustability for proper inter pupillary distance and for snag free stowing of the night vision. A great example of articulating goggles is the DTNVG or PVS-31. Although these are very different systems they both articulate on their bridge.
Now that we understand the difference between the two, we can discuss the pros and cons of both types of binocular night vision… for ease of showing the differences we will list them below. One important note, for the purposes of this article we are focusing on ground optimized, up armored units. It is important to note that while the popular Anvis goggles are a fixed bridge system, they lack the inherent ruggedness discussed below.
- Ruggedness by design: By eliminating the articulating joint, fixed bridge designs eliminate the inherent weak points of an articulating system. This means an all over more durable unit.
- Speed: Since fixed bridge units do not have the ability to pivot the optical pods away from the users eyes, they do not have to be individually adjusted each time to get the pods perfectly in front of the users eyes. This means that they can just be flipped down on the mount and they are right where they need to be.
- Slim design: Even though fixed bridge goggles do not fold back toward the helmet they are generally have an overall slimmer bridge for a nice compact package.
- Height when stowed: Because of the fact that the optical pods do not articulate out the unit must be flipped up on a helmet mount to stow the goggles. This makes the footprint of the helmet taller and can hit the ceiling of vehicles.
- Lack of stowing options: Fixed bridge goggles only move horizontally on the bridge via thumb screws. Because of this the user has to manipulate the helmet mount if they want to scan with a thermal or go unaided.
- Flexibility: Articulating units give the user a lot of flexibility when it comes to how the unit is ran. Users can run the system with both eyes aided, no eyes aided, or only one eye aided. This is helpful when using a handheld thermal or reading ambient lighting conditions.
- Features: Most articulating units have either auto off when flipped up (PVS-15 & PVS-31) or each optical pod independently shuts off when stowed (DTNVG). This prevents damage when not in use.
- Ruggedness: Although most modern goggles are very sturdy an articulating unit is typically inherently weaker than a fixed bridge design like the RNVG. This is because the joint where the articulation happens is exposed and not as rugged as a contained fixed bridge system.
- Price: Articulating units are a more complex housing, so they are typically more expensive than most fixed bridge systems.
- Adjustment: With most articulating units not having IPD stops (inter pupillary distance), the user has to readjust the inter pupillary distance each time they rotate the optical pods. This could take some tweaking to the unexperienced user and take additional time than simply flipping down a fixed bridge system.
There is no right or wrong answer to which system is best for you. We recommend the style of goggle that fits your needs and the style you prefer. As a general rule, if you need to be in an out of vehicles or are scanning with a handheld thermal then we recommend an articulating goggle. If you are a civilian that uses your goggles on the flat range we say go with what fits your needs and priorities best. Both are great options, and both have a place in the market. Do your research and buy informed!