Some Aimpoint® sights are compatible with NVD (night vision devices). This means that the sights can be used daytime, but also in darkness or low light conditions together with NVDs.
The performance of Aimpoint® sights is optimized for use with all generations of night vision devices, but is especially suited for 3rd generation night vision technology.
Aimpoint's unique band-pass coating on the front lens reflects select frequencies of red light at near 100% efficiency. This allows the highest possible dot brightness while transmitting nearly 100% of light in the infrared and near-infrared part of the spectrum.
The result is the clearest, brightest image possible when used with a 3rd generation NVD.
In order to maintain zero, the NVD has to be used behind the sight. It can be mounted on a helmet or on the rail behind the sight.
When you turn the dot intensity switch, the first 4-7 settings (depending on the sight model) are for use with NVDs. This means that the dot will only be visible through a NVD.
If you continue turning the switch, the dot becomes visible to the naked eye, and the sight can be used in daylight.
For visual illustration, check the animation below.