Sights with illuminated reticle

Aiming mark illumination

— the presence in the sight of a special illumination for the aiming mark.

Collimator models and "night lights" have this function by definition — the aiming mark in them represents either a light mark on the lens (in the first case), or a set of pixels on the screen (in the second). But in optics, the backlight is intended for situations where the reticle itself is poorly visible — for example, when aiming at a dark target against a dark background at dusk. Note that the backlight usually requires a battery to work; there are systems that do not require power (tritium illumination), but they are practically never found in civilian sights.