Doctor Doom developed this device, made up of two differente parts: A transmitter no bigger than a button, that was used as a camera, and a portable projector that could be held and manipulated with a single hand. When the projector activated, it broadcasted a holographic image of whatever images were being seen at the transmitter's location, in real time. A single projector could provide images of up to three transmitters at the same time, and some projectors could also send the sound at the transmitter's location - and vice versa, thus favoring teleconferences. Some models of transmitters had a limited range while others allowed for long-range communication without revealing the position of the transmitter.
Doctor Doom used one spherical projector to give an ultimatum to King Vladimir just before deposing him. Years later, he started outfiting his minions and robots, including Doombots, with these devices to monitor their activities. When Prince Rudolfo raided Castle Doom in an attempted coup, he and his men found themselves apparently surrounded by several Doctor Dooms. Most of them were simply shimmering holograms to confuse the attackers, but the last one was not even Doom himself, but an armed Doombot. Although Rudolfo destroyed the Doombot, he was defeated at that point, prey to Doom's Hypno-Probe.
A holographic Doom also entered Spectorcorp's offices to demand a meeting with their CEO Marc Spector. A security guard noticed that Doom projected no shadow and correctly identified him as a hologram, prompting him to vanish, but Spector was contacted nonetheless. Marc Spector -secretly the superhero Moon Knight- later infiltrated Doom's Latverian Consulate and used Doom's holo-technology to project an illusory image on himself, impersonating Mr. Fantastic for a short time. Doom soon understood he was in front of a hologram of his (Doom's) own design, which was hiding someone different than Mr. Fantastic.
The book Machines of Doom Vol 1 1 mistakenly lists this item's first appearance in Avengers #332, but it was really in Avengers #333 - unless we consider previous hologram projectors created by Doom such as the one in Astonishing Tales #1 and Super-Villain Team-Up #5 or the one used by Doom's Scanbot in Fantastic Four vs. the X-Men #2.
The nature of the Hologram Projector is quite different from Doom's Image Projector: The Hologram Projector can reproduce anything Doom thinks of, while the Image Projector can only reproduce Doom. However, the Image Projector provides a Doom that can attack enemies, while the Hologram Projector does not. Besides, the Hologram Projector cannot be incorporated seamless in Doom's Armor