This article concerns itself mainly with "standard frequency" lasers, those that operate in the near infrared, visible light, and ultraviolet spectrums. Masers (microwave lasers) and Ultra-High Frequency weapons, such as Gamma ray and X-ray lasers, will be discussed in their own articles.
Lasers are everywhere in today’s society. Playing CDs and DVDs, scanning groceries, correcting eyesight, and more. But where are all the laser guns?
Lasers work by stimulating populations of atoms into repeatedly emitting photons of a certain frequency and wavelength. Listings of in-depth articles on the exact physics and workings of lasers can be found in the Related Information section at the bottom of this page. Much of the information in this article comes specifically from Fire, Fusion, and Steel: The Traveller Technical Architecture, which has the most detailed dissertation on the design of future laser weapons I’ve ever encountered.
The quick and easy reason for the lack of laser weapons today is power. In order to produce enough of a punch to do at least as much damage as a medium-caliber conventional pistols, a laser must propagate a certain level of output energy (starting at around 1.5 kilojoules) near-instantaneously at the pull of a trigger. Weaker lasers can do damage by firing on a continuous beam on the exact same spot on a target for several seconds at a time, which may be good for mechanical or medical applications but is extremely impractical for actual combat. While the controlled chemical explosions found in conventional rounds can easily deliver this much mechanical punch to a bullet, pumping 1.5+ kj into a millisecond laser pulse with a battery or generator small and light enough to fit into a pistol or a rifle has proven to be quite daunting.
Laser pistols and rifles will probably be preceded first by tactical support versions, which can take advantage of stationary and vehicle-mounted power sources. The most obvious solution is to have a controlled chemical explosion provide the energy as it does for conventional firearms. Explosive Power Generation cartridges would, to their users, function very much like ammunition cartridges for a conventional firearm.
Another solution is to have an array of advanced but conventional batteries carried in a backpack, fanny pack, or belt clip, and attached to the gun via a flexible power cable. This way, the heavy and bulky power source can be kept separate from the gun, making the weapon far easier to handle and aim than it would be otherwise. Advanced generation lasers would use compact in-weapon versions of these technologies, made modular like magazine clips for easy handling and reloading during combat.
Another somewhat significant problem is focusing. Lasers, like most light, will spread out over distance, though dispersion of a laser beam is much less for any given distance than for conventional light. Laser focusing is usually done with specially-designed mirrors, and getting these to focus and align the beam to reach long ranges and still deliver significant damage has proven difficult. While not so much a problem for hand-held weapons (which would only have to function over distances of at most 1000 meters during personal combat), this was one of the major problems with strategic laser weapons developed for SDI, which had to deliver significant damage over hundreds of kilometers or more.
Lasers damage different substances differently. With dry materials such as metal and plastic, it simply burns a hole straight through. The more energetic or higher the frequency of the beam, the farther it can "drill" into the material in a single pulse, perhaps even shooting right through it.
With wet materials, the story is completely different. The energy delivered by the beam manifests itself as heat, and the beam pumps a lot of heat into a target all at once. With water, this means an instantaneous steam explosion.
Organic tissue like skin and muscle are mostly water.
So a laser gun will NOT make neat little holes in the people that it hits. Instead, as the beam hits the skin and the viscera underneath, the water in the tissue explodes instantly into steam very messily, causing wide third and second degree burns in much of the surrounding tissue. This may be made even worse by tough clothing or armor, which would trap the steam and spread it over a larger portion of the body than it would otherwise reach.
Lasers will also very likely cause combustible materials like wood and cloth to instantly burst into flame.
To clear up one very big misconception perpetuated by some science fiction sources: You CANNOT see a laser beam, unless it actually hits a visible object or passes through a visible medium. This is easily demonstrable; get a common laser-pointer, wait until dark, and shine it at a house or a tree across the street. You’ll see a red dot as the laser hits its target, but NOT the beam itself. You can see it, however, if you spray a fine mist of water from a bottle right in front of the pointer; since the water is visible, the beam that hits the mist droplets are reflected or diffracted, and become visible.
So a battle field dominated by laser weapons would NOT be crisscrossed by colorful, movie FX-style beams. It would actually be far more unnerving, in that the deadly beams ARE there, maybe crisscrossing just a few inches from your eyes, but you would never be aware of them until too late.
Laser weapons have a very low firing signature. There is no muzzle flash and their operational noises would be no louder than the hum of your computer. Trying to pinpoint incoming fire would therefore be much harder than with conventional arms. A battlefield dominated by laser weapons would tend to be fairly quiet compared to modern battlefields, making things even more nerve-wracking for the future soldier. Invisible, laser-borne death may hit you at any moment, and even the people standing right next to you may never figure out exactly where the shot came from.
Laser weapons also have no recoil, making repeated fire much easier with them than with conventional arms. Shoulder stocks and such will probably still be present, however, to offer stabilization for precision fire.
A number of countermeasures have been proposed specifically designed to counter laser weapons. However, many of these are frequency specific. I.e., they are designed to work against only a narrow band of light wavelengths, usually one band at a time. Lasers that are capable of changing their beam frequency easily and quickly to defeat these countermeasures will have a decided advantage over those that can’t.
|MAN-PORTABLE LASER BLINDERS|
Tech Level: 10
|China's ZM87 laser blinder, circa 1995.|
These weapons are also sometimes called Dazzlers and are referred to in modern military jargon as "electro optical" weapons.
Today a laser blinder can be a euphemism for a device that can scramble police speed guns, but in the early 1990s, it referred to a far more terrifying military weapon being developed at the time by the US and other countries. Its development was arrested mostly due to international outcry that use of military blinders would be extremely cruel and inhumane, and the weapons were condemned both by the International Red Cross and the United Nations. However, as late as 1995 China was cited to still be developing and selling blinding laser weapons such as the AM87 Neodymium Laser Blinder, and such weapons may already be undergoing second or third generation development there. Also, many nations, including the US, are developing laser weapons whose secondary effects may cause blindness, as the UN conference forbids only dedicated-purpose blinding weapons.
Laser blinders started out somewhat simply as a form of non-lethal crowd control and tactical area denial. The idea was to scan a laser quickly over a crowd, using a low-powered beam to "dazzle" the people into temporary blindness. Unlike other types of laser weapons, the beam would not be tightly focused, in order to hit as large an area as practical, but would still have enough energy density to burn enough of the retina to cause vision loss.
Using the blinder gun rifle-like to target each human target’s eyes was considered impractical, both for crowd-control and battlefield use. What was needed was to play the beam quickly over a wide enough area to hit many potential targets near-simultaneously. This was solved through several methods. One was to use a focusing prism that rapidly moved or rotated on the end of the beam projector. Another was to use a large concave mirror, onto which the focused laser beam was quickly played across and reflected at the targets. Both methods allowed the weapon to cover a wide cone-like area in a fraction of a second, potentially blinding dozens of victims with every pull of the trigger.
Laser blinders also had another insidious innovation; by operating in the near-infrared spectrum, which the eye is transparent to but which does not register as light, laser-blinder weapons can do their damage without invoking the blink-reaction that normally protects the eye.
Laser blinders also have the added advantage of being able to dazzle and blind enemy visual sensors, including those on fighting vehicles, artillery, and missile emplacements. The US military has two prototype anti-sensor laser blinders in development, the Dazer and the Cobra. Both are static lasers (see below) meant primarily to detect and neutralize enemy optical and electro-optical sensors for various weapons systems. As such they are designed for pinpoint fire mode as opposed to the scanning fire mode used for "crowd control" laser blinders.
The big problem that made laser blinding weapons such political plutonium before they were ever even deployed is that the amount of energy needed to temporarily blind and permanently blind a target is a very thin and not easily defined line. Any laser that was capable of temporarily blinding a target in one instance could very easily permanently blind one in another, depending on many variables such as atmospheric conditions, range, orientation of the target, length of exposure, frequency, beam intensity, and more. These problems could not be easily solved, and laser blinders fell out of favor as a form of personnel neutralization and began to be looked upon more for weapon sensor neutralization.
Laser blinders used on a battlefield could have a very devastating effect psychologically on the troops on the receiving end of these weapons.
All other near-infrared and visible light laser weapons mentioned in this section can be used secondarily as laser blinders, either by reflection or diffraction on targets that it hits, or by powering down the beam.
STATIC LASER FIREARMS
Tech Level: 12
A so-called static laser uses a single population of atoms or molecules which are energized by electrical or light input, emit their photons, and fall to a lower energy state, and are then re-energized to emit again, over and over. Many modern real life lasers are static lasers, including ruby lasers, gas lasers, dye lasers, diode lasers, and excimer lasers. The lasers one finds in most appliances, including CD players, supermarket checkout scanners, and laser pointers, are static lasers. A static laser is probably the easiest means of creating a practical laser weapon, as it is a well-used and proven technology. It does have the disadvantage of not being able to easily change frequencies, however.
Also, their rate of fire would tend not be very high, as the electrical power would have to build up to a certain level in the weapon’s capacitors before pumped into the population atoms in order to get a large enough pulse to deliver a significant amount of damage. Because of this, static laser weapons are sometimes called capacitor, or "cap," lasers.
Continuous-beam static lasers are of course in use, but due to the nature of the technology they would not be able to deliver the kind of raw damage as a capacitor-fed pulse could. Advanced static laser weapons could probably switch between high-power capacitor pulse and low-power continuous beam modes.
Static lasers can change frequencies by two general methods: by attaching a modular prism or lens to the beam outlet, or by using dye lasers, which use certain types of complex liquid organic dyes (such as rhodamine 6G) as their energizing population.
CHEMICAL LASER FIREARMS
Tech level: 13
A chemical laser does not use the same population of atoms or molecules over and over, but continuously creates a new energized population which emits its photons and is then discarded. These atoms are not energized per se, but are created in an energized state as the product of an energetic chemical reaction. Like a bullet, chemical reaction cartridges which produce the right type of energized population can be made modular and self-contained, allowing them to be fed into the gun and then ejected in much the same way as standard ammunition. However, getting to this point of miniaturization with the cartridges would be much harder to achieve than the power pack-fed laser weapons.
This chemical reaction process creates energized populations much faster than capacitor-pulsed static lasers, and thus these weapons can have much greater rates of fire at higher energy levels. In fact, machine-gun like auto fire can be achieved with chemical lasers, making them particularly useful on the battlefield. Also, chemical laser frequencies can be altered somewhat by altering the chemicals used to produce the laser population. In other words, if someone firing a chemical laser weapons wants one frequency, he’d use one set of cartridges, and if he wants another frequency, he switches to a different kind of cartridge.
Chemical laser weapons are actively being developed as part of the US government’s ballistic missile defense program.
FREE ELECTRON LASER FIREARMS
Tech Level: 15
The third broad category of laser is a free electron laser (FEL), and is similar in performance to static lasers, but with one critical difference: it is tunable to almost any frequency. An FEL passes an electron beam through a series of magnets which bend the path of the electrons. As the electrons’ paths are bent, they are made to emit or absorb photons. By placing mirrors at both ends of the electron beam, the photons are gathered coherently to form a beam in the usual fashion. Because the electrons are free, and not bound to an atom, they are not locked into any particular quantum energy state, an therefore can absorb or emit photons of any wavelength, depending on how they are manipulated by the magnets. In this way, the FEL laser weapons can actually be tuned to emit different beam frequencies at the touch of a dial.
Lasers weapons that can easily change their beam wavelength have a definitive advantage on a battlefield where laser counter-measures are common. Because counter measures are usually effective against certain light frequencies and not against others, being able to quickly change beam frequency can give a soldier a definitive edge.
Fire, Fusion, and Steel: The Traveller Technical Architecture
On The Web:
How modern day lasers work:
Report on the US laser weapons program circa 1995:http://www.hrw.org/reports/1995/Us2.htm
Article on the state of modern-day laser weapons:http://www.icltd.org/laser_weapons.htm
On Laser Blinders:http://www.phys.ksu.edu/perg/vqm/laserweb/Ch-9/F9s3t4p5.htm
Specifics on Dye Lasers:http://188.8.131.52/lapd/General/Diagnostics/LIF/Dye.html
DOE article on laser weapon research:http://www.eurekalert.org/features/doe/2002-04/dlnl-bff053102.php
An article on lasers in science fiction:http://home.achilles.net/~jtalbot/amateur/movies/myths.html