Invisibility is one of the most hotly-desired technologies of all time.
OK, people may want magic wishing devices, ever-full purses, and similar items, even more – but no one even pretends that they’re technological.
Unfortunately, even in the Old Republic, true invisibility is a pipe dream.
The closest thing to true invisibility is a Counterwave System. The physics gets complicated, but the net effect is to prevent the “cloaked” vehicle (it pretty much has to be a vehicle; this requires a special, rigid, coating and a lot of circuitry underlying it) from radiating electromagnetically.
This is good; it allows a vehicle using such a device to see, to fire weapons (including lasers, since you don’t coat the emitter), and to use repulsor-based drive systems, while remaining electromagnetically invisible. On the downside, the system does not protect against detection by gravitational sensors, particle emission, or the force and causes the vehicle to take a modest amount of additional damage from laser weaponry. It’s also extremely power-hungry, and – since it prevents the vehicle using it from radiating waste energy – leaves a vehicle using the system getting progressively hotter and hotter.
More importantly, it’s generally only useful in space, during dark nights, deep under water, and in other dark environments, since the net effect is to render the “cloaked” vehicle absolutely black – which isn’t exactly inconspicious against a light background.
Black Globe Generators are based on Stygium Crystals – a distinct rarity. They generate a thin, spherical, “shell” around the generator which suppresses all electromagnetic radiation within it. This is good: the shell is absolutely black, and is perfect protection from lasers, radar systems, and similar systems. On the downside, it’s opaque from both sides – which means that, unless you poke some instruments out through the field, and find some non-electromagnetic way to feed their output back (such as by subspace transmission – another incredibly expensive way to do things), you can’t see where you’re going. You can’t fire lasers through it either, and several other weapons will have problems.
Unfortunately, since the field suppresses vacuum-energy frequencies, it constantly dumps energy into the fabric of space-time – resulting in a massive power demand. Worse, the smaller the area cloaked, the greater the range of suppressed frequencies, and thus the higher the already-massive power demand becomes.
Black Globe systems can absorb essentially-limitless amounts of electromagnetic energy however; if you’re ever making a close pass past a star, you may still show up as a globe of absolute blackness, but you won’t even feel a breath of warmth.
More practical engineers usually settle for Active Camouflage Systems. While no such system is perfect, at a distance, in a confused or shadowy environment, or against a bland background, they can be extremely effective. The very best designs can even emit a certain amount of light to blend into illuminated backgrounds, such as the sky.
Unfortunately, the best such systems can generally only be applied to rigid surfaces. Flexible surfaces, such as the classic “invisibility cloak”, greatly limit the resolution and ability to emit light. Secondarily, they’re invariably limited to a particular range of frequencies. If you want to cover enough of the spectrum to affect instruments and a wide variety of optical systems, you’re going to be spending quite a lot.
On the other hand, such systems work perfectly well in an illuminated planetary environment, require very little power, allow the user’s to see quite normally (even if that does require leaving an un-camouflaged area, such systems are far from perfect anyway), and don’t interfere in the slightest with weapons fire or other defenses.
Personal systems are available – often in the form of more-or-less literal “cloaks” – which provide substantial bonuses to their user’s ability to sneak around and pass unnoticed. While rather expensive, they don’t even call for much power.
Higher-quality systems can conceal vehicles quite effectively, especially at long range. At close range, however, perspective, lack of detail, and varying angles of view tend to give the game away – at least to alert, sapient, observers.
In legend, there are systems that can render everything within an area totally transparent to a wide range of frequencies – ignoring the fact that this would effectively blind everyone within the affected area and shut down most technologies.
Similarly legendary are systems which somehow “warp” light around the generator to be re-emitted on the far side or which “pipe” ambient light through the concealed area. Unfortunately, this particular myth begs the question of how any given photon “knows” when it’s time to be re-emitted again and how it’s direction is tracked.
Less legendary, but useful only under specific circumstances, are systems which use modulated shield systems to simply “blur” light which passes near the generator. While these are quite useful if you wish to hide an area against a vague, illuminated, background – such as the sky – the distortion generally gives the system away against any more complex background and they’re fairly useless in space, where vehicles are generally tracked by their own emissions. While Grand Admiral Thrawn would – in a much later time period – make splendid use of such systems, most groups find very little use for them.