Monoculars, Binoculars, and Bi-Oculars
Head-mounted night vision is typically divided into three main categories - monoculars (devices with one optical channel), binoculars (devices with two independent optical channels), and bi-oculars (devices that project a single inbound channel into two optical channels). A fourth category that is outside of the scope of this article are panoramic night vision devices such as the GPNVG-18.
Night Vision Systems are defined by four major parts:
- Objective lens (forward-facing lens)
- Housing (what holds the image intensifier - think about this as the "chassis" of a car) - this is the part that will have the most variability in terms of features
- Intensifier tube (the actual part that amplifies light)
- Ocular lens (rear-facing lens that the operator looks through)
It is important to note that intensifier tubes, objective and ocular lenses can be interchanged between various monocular, binocular, and even bi-ocular devices. The housing will determine the format of the device, as well as the form factor and features.
Monoculars are, by volume, some of the most widely-used night vision devices in existence. These devices collect light through a single channel, amplifies it via the single image intensifier tube inside, and projects it to one of the user's eyes. Benefits of monoculars are reduced overall weight and size, reduced cost, and at times, higher levels of situational awareness due to the user's un-aided eye providing supplementary information about surrounding ambient light levels. This last aspect of monoculars is often over-looked but can be a very powerful tool. The typical field of view (FOV) of monocular night vision systems is about 40 degrees, whereas unaided night vision (your natural eyesight) has 135 degrees.
For common monoculars and their features and considerations, click HERE.
Binoculars are the next most-popular group and one that most users gravitate towards - and for good reason. Binocular night vision have two independent optical channels that gather light, use two image intensifier tubes, and project to two optical channels - left and right eye. This is most similar to "normal" stereoscopic vision that most individuals are used to using during their day-to-day lives. Because stereoscopic vision is much more natural, this is often the option that a lot of users gravitate towards. However, because there are now two additional lenses, and one additional intensifier, the starting cost of binocular night vision is almost always higher.
It should be noted - and stressed - that most binocular night vision systems do not offer substantially more visual information. At most binoculars provide a few more degrees of FOV. However, systems like the Panobridge, and the RPNVG provide the ability for users to point each optical pod on a binocular sideways on the horizontal plane, providing greater than the standard ~40 degrees of Field of View, with the Panobridge providing up to 75 degrees of Field of View - an increase of almost 100% more visual data. The downside of these panning night vision systems is reduced depth perception due to the lack of overlap between the two optical channels.
For more information on common binoculars, their features & considerations, click HERE.