Holographic Sight

A Holographic Weapon Sight is a non-magnifying gun sight that allows the user to look through a glass optical window and see a cross hair reticle image superimposed at a distance on the field of view. The hologram of the reticle is built into the window and is illuminated by a laser diode.

Battlefield Play4Free
In Battlefield Play4Free, all assault rifles, sniper rifles, SMGs and LMGs can be equipped with a Holosight. The differences seem to be purely aesthetic, although they can increase accuracy by a little and they can free up some open space instead of using the closed out iron sights. The Mk14 EBRhas a Holosight by default. When weapon customization got introduced to the game, all weapons (except pistols) can now be modified with a Holographic Sight.

Battlefield 3
The Holographic Sight is an attachment in Battlefield 3. It appears to be an EOTech 552-style sight.

Despite being a non-magnifying sight in real life, the Holographic Sight in-game uses 1.5&times; magnification, but shares the same aiming speed with the Red Dot Sight, Kobra, or ironsights, not slowing down aiming at all.

Its Russian counterpart is the PKA-S.

It is seen on the M240 LMG in the "Fault Line" gameplay trailer, carried by a US Marine and later by the player. It is also seen on the M4A1 Carbine on the Battlefield 3 box art. During the live console debut on Late Night with Jimmy Fallon, the EOTech seems to replace the ACOG formerly seen during the Fault Line trailers.

Bugs

 * Sometimes, the reticle on the sight disappears. This can be fixed by re-entering the server.

Trivia
In the earlier stages of Battlefield 3 the holographic sight had its reticle ,even when unzoomed.