Hologram

A hologram is a three-dimensional photograph recorded via refracted lasers onto a two-dimensional surface. In the Fallout world, holograms appear as they do in other works of science fiction, i.e. as three-dimensional volumetric projections of objects and people made of beams of monochromatic light and outputted through advanced projector that utilizes holographic technology.

Background
 Before the war, research efforts were undertaken to weaponize holography, such as at the Big MT research facility. Based on RobCo Stealth Boy technology reverse-engineered from captured Chinese stealth suits, the researchers attempted to create a design capable of matching the Chinese technological edge. Despite promising initial results, holograms required excessive amounts of electricity to power, as well as the cost of materials and manufacturing, greatly limiting their potential. Mobile holograms, and those that could be deployed as weapons, never reached any popularity in the United States likely due to the recent developments in 2077.

Person holography was pursued at Big MT, under the name "Hologram Project," where the entire program teetered on the brink of cancellation due to poor results. However, the insistence of Frederick Sinclair, support from N.E. and significant financial backing from Sinclair's pockets kept it going for his personal project, the Sierra Madre Casino & Resort. The researchers at Big MT's Z-38 lightwave dynamics research facility (equipped with an enormous laser array) developed the first working, mobile holograms, creating 3-D human figures (including a replica of Sinclair's love Vera Keyes). This iteration of holograms and their functionality was limited as they were only good as holographic greeters and walking cameras; completely unsuited for combat. Its only weak point were the emitters, which could be destroyed despite their space-age alloy housing or disabled if someone tampered with circuits. However if the emitters were safe, custom energy recycling emitters could keep them going indefinitely. 

Outside of Big MT and the Sierra Madre, Professor Calvert developed his own hologram projector to communicate with the Point Lookout tribals in Point Lookout, who worshipped him as a god.

Vault-Tec also has access to hologram technology in the form of a holographic communications device, capable of projecting one's face between two communicators holographic image, which was used in the Vault prototype and the Secret Vault.

Characteristics
 Sierra Madre holograms, as projections, rather than actual physical entities, are invulnerable to damage. They are divided into two distinct groups: Service and security holograms, all modeled after actual Sierra Madre personnel. The former are simple utility projections, providing the automated systems of the Villa and the casino (such as vending points or casino games) with a user-friendly interface. These are non-hostile and are not equipped with an EBE device. In case of an emergency, the service holograms are disabled and replaced with security variants.

The security holograms are a completely different affair. As invulnerable as the service holograms, they are designed for enforcing order and security at the casino and the Villa, designed to supplant traditional security guards. Their security protocols allow them to perceive their environment in a roughly 90 degree cone in front of them, with the planned 360 degree perception arc upgrade never materializing due to the war. These blindspots represent the only advantage an unauthorized invader has over the holograms, as staying out of the hologram's field of view will prevent retaliation.

If detected, the holograms will first display a warning color (changing their silhouette to yellow), and then transfer to engagement mode (signified by a red-colored silhouette), attempting to subdue the offender with their discharge beams. The holograms were programmed to engage intruders and people committing criminal activities. All holograms in the Sierra Madre have their EBE systems configured to kill, rather than subdue. If the target evades the hologram, it will resume its normal routine after some time. This is made easier by the fact that the emitters have a limited range and will only pursue the target as far as their perimeter allows.

The only way to permanently disable a hologram is to destroy its emitter. Although housed in space-age alloys, they can be destroyed with blunt force or disabled by tampering with their circuits. 

Appearances
Holograms appear in the Fallout 3 add-ons Point Lookout and Mothership Zeta, in the Fallout: New Vegas add-ons Dead Money and Old World Blues and in Fallout: Brotherhood of Steel.

Behind the scenes
They were also to appear in Van Buren, the canceled Fallout 3 by Black Isle Studios.

Bugs

 * When seeing a hologram and then quickloading the game, the hologram's color can go dark.They still flicker, but they won't be blue anymore, and it may be hard to see them. Only way to fix this is to open console click on the hologram till the hologram non-player character's ref. ID shows up and type "resurrect."
 * Rarely, they can be killed with gas bombs, frag grenades or C4 and give 10-20 XP.