The Holographic masking system, or Incursion Technology is a type of stealth technology used to create a false image of a starship for purposes of stealth and deception.
Conceptually the process is quite simply, the vessel selects a preferred identity and then uses its array of holographic emitters to create the image of that ship around its self, presumably the technology is somewhat more sophisticated so that the user might take on the appropriate warp field frequency and other markers that would give away its true origins.
Holographic technology has been utilised throughout history as a means of disguise and deception, but it was not until the 22nd century that anyone conceived of using it to falsify the existence of a starship.
The Romulans were the first to use the idea, modifying a number of T'Liss-class birds-of-prey into remote drones to carry out attacks on other vessels. They utilised the system to take on the identity of other species vessels in the hopes creating tensions between usually amicable races. The earliest deployments of these vessels were thwarted by the Starship Enterprise, and in fact resulted in a greater feeling of unity between the species the Romulans were hoping to propel into war. The Romulans planned to use more of these modified vessels in future attacks but were unable to obtain the necessary special pilots. (ENT episodes: "Babel One", "United", "The Aenar"; ENT novel: The Good That Men Do)
In the 24th century, the Federation developed their own version of the system, which was deployed on the USS Incursion, a Starfleet Intelligence vessel which used the system to go undercover into enemy territory. The ability to hide amongst their enemies was a crucial factor in the Incursion's successful defeat of the Wardens in 2377 and later they were a crucial cog in the war with Species 8472, taking on the identity of 8472 vessels to infiltrate their space and locate installations. (TNG video games: Away Team, Armada II)
In 2379, the Romulan Tal Shiar covertly entered Federation Space and stole the experimental Incursion Technology from Starfleet Test Range Theta. The Romulans viewed the technology as similar enough to a cloaking device that it would violate the Federation's stipulation in the Treaty of Algeron that forbade the Federation from researching cloaking technology. They then began to refit their own ship with the technology an attempted to start a war between the Federation and Klingons. Eventually the Federation and Klingons both discovered this and begain to attack the Tal Shiar shipyards and other important bases. After the conflict ended the Federation agreed to stop all research into Incursion Technology. (TNG video game: Starfleet Command III)
- Whether or not Starfleet took inspiration from the earlier Romulan usage of the concept is unknown, however it would seem the Starfleet system was a significant step forward in the concept to warrant the Romulans stealing it.
- See also: Cloaking device