Articulation

Articulation, in the context of night vision, refers to the ability of some binocular devices (and by extension, monocular and binocular bridges) to swivel each pod around the forwards axis.

Advantages

Articulated devices have multiple advantages.

• Selective use of each side of a binocular, advantageous in some conditions, like aiming a firearm
• Ability to move pods out of the field of view quickly and without having to move the entire device into the stored position on top of the helmet
• When in the stored position on top of the helmet, the pods can be swiveled until flush with the helmet, moving the center of gravity back and reducing the overall height, making it less cumbersome to wear in stowed position when in tight spaces, e.g. vehicles or doorways

Disadvantages

A downside of the articulation is the introduction of a failure point with the rotating joint. Joints breaking due to accidental collisions or drops have been documented on several occasions.

Some articulated devices feature inter-pupillary distance (IPD) adjustment by providing thumb screws to change where the swiveling motion ends. This, however, means that depending on the IPD, the pods have a different rotation relative to each other, which makes "simple collimation" using rotating eyepieces imperfect. "True collimation" used by some military night vision devices however is still possible.