Star Wars: The Strategic Defense Initiative

Ok time for a little science and fun..
I know you may be wondering sometimes, while watching the outstanding skills of a jedi with his lightsaber, is it actually possible to have laser-guns ?

The coherency of laser light is useful for measurements, communications, and information storage, but the power of lasers motivates
other applications.

It may seem weird but per unit area, lasers can be brighter than the sun, and such energy is remarkably destructive when it is concentrated on a target for any length of time. Destructive energy produced by powerful lasers can actually have important medical uses such as eye surgery etc.

Lasers can also be used in war. Many weapon systems already use lasers but only for guidance—the beam is part of the apparatus instead of being the weapon itself.

But the “death rays” of early science fiction stories are possible, in the form of high-power lasers. Although handheld laser weapons are not likely in the
near future (such as a lightsaber) because they do not contain enough of the medium’s material to generate powerful beams but powerful lasers do exist! Among the strongest are CO₂ lasers that emit beams with a power of a billion  watts or more, millions of times the power of the fastest car
engines. So creating such a small weapon that can generate such giagentic amounts of energy is quite impossible but keep dreaming...

Now little history...

One of the most ambitious plans for the military use of lasers
came to light when President Ronald Reagan made a speech in 1983 proposing the Strategic Defense Initiative (SDI). In the 1980s the cold war with the Soviet Union continued to rage, and
President Reagan’s idea was to use a variety of defensive weapons to intercept and defeat a possible nuclear attack.
A key element of SDI was a shield of protection created by satellite-based X-ray lasers. X-rays have high frequencies and there-fore a tremendous amount of energy, useful for penetrating tissue
during medical exams or, at high intensity, burning an enemy’s missile!!! Using an array of satellite sensor systems to detect rocket launches, any missile launched by the Soviet Union would be
intercepted and destroyed by high-power laser beams in midair, long before it reached United States soil.
The proposal became controversial for several reasons, including expense, practicality, and the effect such a system would have on already tense relations with the Soviet Union.

Source :Light and Optics , Kyle Kirkland PhD