Deflector shields, also known as deflector screens, deflectors or simply shields, were translucent or transparent energy fields produced by deflector shield generators. These generators could be placed on planets, droids, starships, space stations and individual buildings. The primary purpose of the shield was to block or deflect projectiles and lasers from hitting the object under protection. They could also provide a significant atmospheric speed boost, in some cases 36 times the speed of sound.
- "Their deflector shield is too strong."
- ―Ric Olié
There were two distinct types of deflector shield: ray shields, also known as energy shields, and particle shields. The former protected against energy-based attacks, such as blaster or laser cannon fire, while the latter was developed in response to physical attacks, ranging from projectile missiles and incoming vehicles to asteroids and meteors. Commonly, larger ships and structures were protected by both types of shield, though starfighters often only projected ray shields.[source?] Ray shields were also used as capture devices onboard capital ships; Obi-Wan Kenobi, Anakin Skywalker and Supreme Chancellor Palpatine were caught in a ray shield trap onboard Invisible Hand. Although designed to counter energy attacks, the energy given off by the ray shield would likely have disintegrated the Jedi duo had they attempted to pass through it.
The Gungan shields used during the Battle of Naboo blocked lasers, but droids could pass through because of their relatively slow movement in comparison to the laser bolts. Some shields only held back anything with a high-energy output, allowing sentients to pass through unharmed. Others were deadly to anything upon contact. Some Trade Federation droids, notably the droideka, were equipped with shields making them almost invincible in infantry combat.
Deflector shields worked in a layered defense fashion: A volumetric field effect extended out from the surface of the shield projector, attempting to reduce the coherency of any beam attacks and deflect physical objects. The shield itself behaved in a manner similar to that of a thermally conductive material—energy applied was quickly diffused and re-radiated back into the environment, but the shield itself could also absorb some of the energy. The absorbed energy was shunted into heat sinks, and re-radiated at a lesser rate by the shield and neutrino radiators. The use of deflector shields on starfighters and other small craft, made them capable of hypersonic speeds in planetary atmospheres.
The strength of a deflector shield was a factor depending on how close the shield was to the projector, the efficiency of the projector, the power applied, and the surface area of the shield. It was common for starship deflectors to be projected a few molecules underneath the hull plating, and then extended outwards to protect hull integrity. Starship shields could handle massive amounts of energy or punishment, although it was possible to disable a shield by concentrating fire on a specific location.
Aside from the standard defensive shields carried by most ships, there were other variants:
- Shift shields: These shields protected any ship traveling in hyperspace from collisions with interstellar atoms, dust, or dark matter. An unprotected collision would destroy the ship. Failure of the shift shields in a meteor shower was how Darth Vader explained the loss of Tantive IV to the Imperial Senate prior to its dissolution.
- Relativistic shields: Not shields in the classic sense, but relativistic shields still insulated the user from outside forces, thus justifying their name. Under the normal application of physical laws, as one accelerated to speeds approaching that of light, time would dilate. Time flow was slowed for the traveler, yet for any (relatively) stationary observers, their specific experience of time would be much more rapid than the close-to-lightspeed traveler. Relativistic shields or Stasis fields effectively anchored the contents of the field to a specific relative condition of time passage. This function was essential for travel in hyperspace as it is strongly indicated that physical laws and phenomena do not behave the same there as in Realspace. Without Stasis fields, after a brief hyperspace jump, perhaps only seconds would have passed, or perhaps one would find themselves untold thousands of years in the future. See also: stasis fields.
Deflector shields were first developed during the early years of space exploration, designed to absorb heat and radiation encountered in space and within a planetary atmosphere. Before the introduction of deflector shields, pilots had to rely solely on thick, armored hulls and panels of reflective armor for protection against meteors and laser attacks. More advanced versions of the energy shield were developed centuries later, until eventually modern shielding was able to combine ray and particle protection. Eventually, shield technology improved enough to allow some ground vehicles to have dedicated shield generators.
Some of the largest and most powerful deflector shields produced were those that protected the Death Star battlestations of the Galactic Empire. The second Death Star was protected by a SLD-26 planetary shield generator on the moon of Endor. This effectively forestalled any attack against the station, until Han Solo's strike team destroyed the generator.
By the time of the Battle of Naboo, personal shields that covered an entire being existed, but produced radiation and magnetic fields that were dangerous for sustained use.
During the Galactic Civil War through the Yuuzhan Vong War, however, personal shield tech was all but lost. Very few armies equipped their soldiers with personal shielding, due to their ineffectiveness with modern weapon technologies, assuming that they were small enough for personal use. Notable exceptions include the Trade Federation droidekas, the mercenary Kyle Katarn and his student Jaden Korr, Durge, Republic clone commandos, and possibly[source?] the bounty hunters Boba Fett and Jango Fett.