Cloaking device

A cloaking device was a technology utilized by numerous species to render ships, stations, equipment, personal and even planets invisible to the naked eye and/or sensors.

Applications
Cloaking devices were most commonly employed on starships, often for purposes of subterfuge, allowing a vessel to move unhindered by unaware opposition. However, cloaking devices were also been used for various other purposes to make best use of the technology.

The power consumption of cloaking devices was often seen as a limiting factor, making even cloaking small starships difficult, however, with the correct technical expertise it was possible to cloak much larger objects. The planet Aldea was equipped with a cloaking device capable of making the entire planet invisible, though it did have the unfortunate side effect of damaging the planet's ozone layer, resulting in widespread radiation poisoning from the Aldean sun's ultraviolet rays, resulting in the Aldean race become sterile. 

Large scale cloaking was also used by the Sphere Builders to hide their spheres in the Delphic Expanse. Cloaking was also used at smaller scales. The Federation and Romulan Star Empire both utilized cloaking mines. 

Personal cloaking devices were also been used by both states, in isolation suits by the Federation and cloaking bands by the Romulans. 

History
Cloaking technology existed in the galaxy for some time, however in the affairs of the major Alpha and Beta Quadrant powers the technology only started to come into use in the 22nd century.

The 22nd century
Humans first encountered cloaking technology in confrontations with the Suliban Cabal who used the technology on their cell ships and stealth cruisers. After their initial encounters, the Enterprise (NX-01) was fitted with Quantum beacons (provided by temporal agent Daniels) capable of penetrating Suliban cloaks. (, et al.)

The Enterprise encountered three other species who employed stealth technology (analogous to cloaking technology): The Xyrillians, who used it to hide out of fear rather than for great tactical advantage, the Sphere Builders, and the Romulans.

The Sphere Builders were an extra-dimensional race who used cloaking fields to hide their space transforming spheres in the Delphic Expanse. The spheres had been placed in the expanse approximately a thousand years ago and the Sphere Builders had temporal technologies so the origins of this particular type of cloak are as mysterious as those of the Suliban. In 2152 the Enterprise stumbled into a cloaked Romulan mine field. By using the quantum beacons they could successfully detect the mines but not the two Birds-of-Prey in the area. This encounter was a one off though, Romulan stealth technology was still very much in its infancy, the cloaked mines were considered a relative success but the power requirements for cloaking a whole ship were problematic; sometime after the encounter with the Enterprise, the prototype cloaking ship Praetor Pontilus was destroyed in an antimatter containment failure caused by its stealth systems. It would be decades until a successful system could be developed. 

An arms race
The Romulans finally developed a successful cloaking system by 2266, which they tested on a next generation Bird-of-Prey, that they dubbed a ghost ship, in raids against Federation outposts along the neutral zone. 

The new Romulan cloak used so much power it precluded the use of weaponry and warp drive and the USS Enterprise (NCC-1701) was able to track it. However it could still be considered a success and the Romulans quickly advanced the design to make its use more practical. 

While the Romulans were developing their new device Klingon agents became aware of it and the Klingon operative Korlat was sent to begin talks with the Romulans to make an alliance between the two powers, with the Klingons hoping to gain access to the technology in the process. The alliance was agreed upon by the power-hungry new praetor, though other parts of the Romulan government saw other advantages in the alliance, such as "containing" the Cardassians. 

As they hoped the Klingons did receive cloaking technology in the alliance, while the Romulans were given Klingon starships. (et al.)

With two enemy states using cloaking technology, the Federation was keen to find ways to detect cloaked vessels to the extent that they even stole a Romulan cloaking devise from a Romulan battlecruiser in 2268. Over the next few decades the Federation learned to detect sensor blips associated with cloaks; in return, cloaking technology advanced. In 2293 the Klingons successfully modified a Bird-of-Prey to be able to fire weapons while cloaked. Captain Kirk and his crew eventually defeated this vessel by using a specially modified torpedo which tracked the ships plasma exhausts. 

For a significant period of time Dr Scott Heisenberg was credited for single handedly refining Starfleet's sensors to detect Romulan cloaking devices. However this period came to an end when the Romulans retreated behind their boarders following the Tomed Incident. 

By the 24th century cloak detection was becoming commonplace; Federation borders used gravimetric sensor nets and interphase scanners. The Romulans countered this by improving their interphase generators. In 2368 the USS Enterprise (NCC-1701-D)'s chief engineer Geordi La Forge developed a more advanced technique, the tachyon detection grid, using tachyon beams transmitted between different locations to expose cloaked vessels. 

The Dominion and Cardassians used antiproton beams to located cloaked ships. 

By 2379, the latest iteration of the cloak had overcome all these problems. The Warbird Scimitar's cloak did not give off any tachyon emissions or residual antiprotons, making it undetectable. In addition, the Scimitar could maintain shields and fire through its cloak. The Scimitar was only stopped by the heroic efforts of the USS Enterprise (NCC-1701-E)'s crew, in particular Commander Data, who sacrificed himself to destroy the Warbird. 

Later development
In an alternate future created by the formation of the Red wormhole (which started the War of the Prophets), by 2400 the Romulan Star Empire had developed a more advanced effective cloak known as a transmorphic cloaking device, which used biogenic components obtained from Grigari technology. These transmorphic cloaks made the ships virtually undetectable. This future timeline was erased by the crew of the USS Defiant (NX-74205) (I). 
 * The novel does not specify how transmorphic cloaks differed functionally from standard cloaking devices.

The Federation and cloaking technology
Under the Treaty of Algeron, the Federation was banned from using cloaking technology without the explicit permission of the Romulans. However, before and throughout the 24th century, the Federation was active in the development of cloaking technology but did not implement it in the fleet. 

The Federation also secretly developed an interphase cloaking device in 2358. However, the test ship for the device, the USS Pegasus (NCC-53847), was lost. The Pegasus was rediscovered in an asteroid field in 2370, where the USS Enterprise (NCC-1701-D) recovered and used the interphase cloak before making its existence known to a Romulan Warbird in the vicinity. 

The Federation occasionally circumvented the Treaty of Algeron by enlisting the aid of cloak-enabled Klingon ships in certain operations. 

Both incarnations of the USS Defiant (NX-74205) were fitted with Romulan cloaking devices, under special arrangement with the Romulans that the cloak only be used in the Gamma Quadrant, and that Starfleet share all intelligence thus gathered with the Romulans. Such restrictions, however, did not prevented occasional unauthorized use of the cloak by Defiant commanders Benjamin Sisko and Elias Vaughn (, et al.)

Following the Dominion War the Romulan Senate moved to allow the Defiant to keep the cloak, recognizing the importance of the vessel, and DS9, as the first line of defense against further Dominion attacks. 

In 2375, a cloaked Federation holoship was discovered on planet Ba'ku, though this vessel was initially utilized by Section 31, who frequently bypassed legality in favor of their goals. 

The Ba'ku duck-blind mission also made use of small scale cloaks in isolation suits. 
 * The use cloaks in isolation suits may suggest the Treaty of Algernon cloaking ban only applies to larger scale employment on starships and facilities.

In 2380, the USS Titan deployed a cloak on a shuttle during operations undertaken at the behest of the Romulan government. 

Throughout the 2370s, the Federation encrypted the means of cloaking in the computers of all new starships so that it would be available to Federation vessel in cases of extreme need, although the data could only be accessed with the access codes of an admiral. In 2380, the USS Enterprise (NCC-1701-E) was authorised by Admiral Kathryn Janeway to use this data to cloak the ship for a sneak attack on a Borg cube.

At the time the Federation was also reconsidering its relationship with the then-shattered and unstable Romulan Empire and the restrictions of the Treaty of Algeron. 

In the Delta Quadrant
In her time in the Delta Quadrant, the USS Voyager encountered relatively few species with cloaking technology. Delta Quadrant species know to use cloaking technology include the Ba'Neth and the Hierarchy. (, et al.)

The Voth and Srivani made use of interphase cloaking devices. 


 * It is also worthy of note that the Borg, in their thousands of years of existence and many recorded encounters with cloak capable species, must have at some point assimilated cloaking technology. Though to date they have not been depicted using the technolgy.

In the mirror universe
In the mirror universe cloaks were also used by the Suliban in the 22nd century. The ISS Enterprise (NX-01) used a Suliban cloaking devise from a captured cell ship to enter Tholian space in 2155. The Enterprise was able to use weapons through the cloak. 

In the 23rd century the Klingons, like their regular universe counterparts, developed a cloak which could be fired through. They planned to use a fleet of these vessels to attack the Terran Empire. However, the fleet in construction was destroyed when Praxis exploded. 

The Klingon-Cardassian Alliance of the 24th century also had cloaking technology used on number of ships. However, in 2375 the Alliance kidnapped the regular universe Grand Nagus Zek to blackmail Quark into stealing a Klingon cloaking devise from a regular universe vessel. 
 * This was either a slightly different mirror universe (several variations of the mirror universe have been established) or just as in the regular universe cloaks and sensors had advanced to a point where a new type of cloak was required.

Interphase cloaks

 * See main article: Interphase cloaking device.

Along side the development of standard cloaks all three of the major powers experimented in the development of interphasic cloaks. An interphasic cloak will not just make the target invisible but also capable of passing through solid materials. The Federation was successful in developing the technology in 2358 though that fact was unknown to them for some time when the test ship for the device the USS Pegasus (NCC-53847) was lost. The Pegasus was rediscovered in an asteroid field in 2370 where the Enterprise-D recovered and used the interphase cloak before making its existence known to a Romulan Warbird in the vicinity. 

The Klingons also tried and failed to develop their own phase cloak, as did the Romulans. The Klingons abandoned their attempts while the Romulans' initially failed. By 2376, the Romulans had succeeded and implemented phase cloaks in Tal Shiar vessels. 

Dark Matter cloaks
A new form of cloaking technology was developed by the Romulan Star Empire in 2356 with the aid of the rogue Shepherd Ambassador Lhiau. This form of cloak was undetectable by normal means and was capable of firing when cloaked. This was available to at least thirteen Romulan warbirds which were interfaced with advanced Shepherd technology. There were numerous complications with this form of cloaking as it produced a mutated strain of Dark matter that infected the crew causing madness as well as death. This brought about an end to this program which was discontinued considering the dangers of dark matter. 

Transmorphic cloaks
A newly developed form of cloaking created by the New Romulan Star Empire in the alternate future produced by the War of the Prophets. This technology was virtually undetectable by its enemies but was only possible through the addition of Grigari organic components. 

Tantalus mask
The Tantalus mask was another form of cloaking technology used by the First Federation which was indetectable by gravimetric distortions or radiation making it superior to the standard cloak. 

Users of cloaking technology

 * Cardassian Union
 * Obsidian Order Keldon class
 * Hierarchy
 * Klingon Empire
 * Klingon-Cardassian Alliance (MU)
 * Romulan Star Empire
 * 22nd century Bird-of-Prey • 23rd century Bird of Prey • •  •  •
 * Sphere Builders
 * Suliban Cabal
 * Cell-ship • Stealth Cruisers
 * The Terran Empire (MU)
 * ISS Enterprise NX-01
 * The United Federation of Planets
 * USS Pegasus (NCC-53847) • USS Defiant (NX-74205) • USS Enterprise (NCC-1701-E)
 * Voth
 * Xyrillians
 * Voth
 * Xyrillians

Appendices

 * See also: Holographic masking system