Your Own Ray Gun
On Building the
personal hand-held integrated light actuated neon defence energy
or Light Amplification by Stimulated Emission of Radiation. We all know
about them: they run our CD players, gaze into our eyes, perform minor
surgery, act as high tech pointers in lectures, oh, and DESTROY ALL
BEFORE THEM. At least, thats what Reagan wanted, and who can blame
him? Hed seen Star Wars and, with touching originality, named
a government program after it.
Who can decide what to call these things? Laser guns, phasers, ray guns,
beam weapons, blaster rays, disintegrators, and on and on and on. What
we really need is a marketing focus group to brainstorm a really catchy,
commercially viable moniker for the personal hand-held integrated light
actuated neon defence energy rifle mmm, PHILANDER is not the
family oriented image we need for such a useful domestic appliance.
Especially as people who use the weapon would be PHILANDERers.
Still, lets bike our suggestions over to Dominic and Harvey at
the agency, theyll come up with something
Perhaps for personal defence there is something rather attractive about
a non-lethal means of disabling a naughty person. We have the Taser,
of course, but a laser weapon, factory-set to stun, could actually be
quite useful for any number of things: law enforcement, nervous pedestrians
in dodgy areas and, of course, having a laugh. And there is the problem;
no sooner is the first PHILANDER on the market than some criminally
inclined school kids get hold of one and render their physical education
teacher insensible, or should I say unconscious, most being insensible
Thats what I would have done, hating rugby as I did: the problem
is that every denizen of the educational system has his or her particularly
hated subject and they run the full gamut. That means that by first
break every teacher in the establishment would be comatose
other hand, who could tell?
So, heres the science bit, as Jennifer Rachel Aniston
so memorably said while flicking her eponymous hairstyle a couple of
years back. Anything that produces light does so through electrons changing
orbit and releasing photonsthe reduction of an electrons
energy level to a ground state from an excited state produces light.
Usually this happens randomlythe light could be pulsed in any
direction. However, Einstein (he crops up all over the place, doesnt
he?) realised that if a photon hits an atom that is already excited
it releases a new photon that is identical to the incoming photon, producing
an effect called "stimulated emission". Really a sort of cloning
which amplifies the number of photons.
This all happens in the controlled lasing medium of a laser, which is
pumped so that many atoms get excited electrons, increasing the population
inversion, which is the number of atoms in the higher energy state
against those in the ground state.
So, because in laser light all the crests and troughs of
the wave line up with each other and all travel in the same direction
it is much more ordered than ordinary common or garden light. The orderly
nature of lasers gives us the ability to control it for precision applications,
and means that it is more powerful, as it can be focused more efficiently.
If we were talking potential weapons then the best bet are CO2 lasers,
because they emit in the infrared and microwave region of the spectrum.
As infrared is basically heat these lasers can melt the materials they
are focused on, even cutting steel and are even capable, some say, of
heating a pot noodle evenly.
Where does that leave us in the personal ray gun stakes? Well you might
as well get a laser pointer because lasers with any significant power
are pretty big. Even if they could be made at a portable size then we
are still restricted to giving somebody a mild case of sunburn and not
a lot else. In the long run it may be that giving any potential attacker
a case of sunburn may be sufficienteven criminals want to look
their best in this image obsessed worldand skin cancer doesnt
look good on anyone.
As far as space-borne lasers go, ostensibly this seems a lot more likely,
there being less in the way of size and weight restrictions in outer
space. Fortunately even the stimulated emissions of lasers lose their
coherence over a relatively short distance. After only a few hundred
miles were back to tanning strength only. So, unless any government
wants to undertake a mass program of melanoma induction in an enemy
territory, were not going to see any scenes from Independence
Day replayed (thank goodness).
On the personal level, then, if you must PHILANDER Id recommend
you start working out to enable you to carry the kit. But, of course,
if you work out to that extent nobody is going to bother you anyway
© Brian Runciman May 2003
The British Computer Society
Runciman writes about science for Hacks from time to time.
all rights reserved