Lasers, Comments & Links
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I like lasers; this is due to their versatility, potential
beauty, power and ability to assist science in a variety of ways - medical
science for example, where lasers are being used to repair defective lens
muscles in the eye - or even re-welding optic nerves back to retinas. They
can also be used for a method of temperature measurement where other means
are unrealistic. For example a Torus Ring -Tokamak- fusion device which
has core temperatures far exceeding that of the surface of the sun. Actually,
although it has nothing to do with lasers whatsoever, you really should
take a look at the JET (Joint European Torus) project at their WEBSITE
if you are fascinated in leading edge technology, you will find it awe
inspiring. If you are seriously interested, they do organise visits around
the place, regard it as a "must see" - anything which has to
have it's own private 440KV pylons to the nearest power station (Didcot)
is doing something serious. The power station bless it, is only any good
for powering a couple of flywheel generators. Over a period of about 20
minutes Didcot provides the power to wind some rather large flywheels upto
speed. When they push the big button, the flywheel generators convert the
stored energy back to electricity - in a few seconds. Understandably, things
can get quite warm: 7.1 Million Amperes in the plasma ring if memory serves,
200 Million Degrees C ion temperature being the result of about half that
current, 100 Million degrees being a minimum for fusion and 300 Million
Degrees having been achevied for a brief period.
Where were we? Oh, yes - slurps tea - lasers, was beginning
to look like an advert wasn't it?
Some lasers are tiny little things which read CD and convert
the little peaks and troughs in the CD to electrical signals and, ultimately,
sound. Slightly larger lasers are found in small FX lighting like the "Laser
Crab", a popular device using a 5mW red laser diode and a couple of
motor driven mirrors. This can produce a pleasing effect - particularly
if used with a fog machine or in a smoky atmosphere. However you do need
almost complete darkness for a good effect.
Lasers come in a variety of classes, depending upon their
frequency (colour) and their output power. A high visibility (635nM) red
laser at 5mW would be a class IIIB. Anything over a class I should be regarded
with respect because although 5mW cannot cut or burn, it is strong enough
to kill off the cones and rods in the eye. Hence the rather dry phrase
laser enthusiasts often sign off with: Don't look into the beam with your
remaining good eye. When power levels get higher - certainly more than
50-100mW, then even reflected light should be handled with care - particularly
if the surface is fairly reflective. Watt class lasers can blind instantly
and irreparably.
It is possible to build your own laser, sometimes very
cheaply. You do have to have a knack for improvisation however, glass blowing
for example. If you cannot blow glass you can always arrange to have someone
do it for you, there are glass blowers all over most countries, pretty
much any of them will do something specific for you - and often cheaper
than you might imagine. You should also contact a neon sign maker too for
a few ready made metal/glass electrodes as binding metal contacts through
glass yourself is difficult - due to the different cooling/contraction
ratios. A nitrogen laser is probably the easiest to contruct - the gas
does not need to be pure - you can even use air if you aren't too fussed
about performance levels. the downside however is that you need to have
some rather hefty voltages flying around and the output from the laser
is invisible. The laser can burn and cut if reasonably powerful, it can
also blind easily as the blink reflex is inhibited as the laser output
is not in the visible spectrum. If you do a search - excite, webcrawler
et al - on Nitrogen laser and DIY, you should find some plans FOC on the
net. The links below may also be useful too.
This page will increase in detail and complexity if enough
people wish it too, at the moment I'm just trying to put a "framework"
in place for more things to come. If you have any requests for further
information, links, pictures or facts, send
me a note and I'll have a go when I next feel like a keyboard session.
Can't say fairer than that can I? I usually answer Email around 0:00 GMT
/ zulu.
Laser Links
LaserFX
Main Page - visit the "back stage" area
Holoshop - Holograms & Lasers,
second hand stuff too sometimes
MWK Lasers - Optics, Lasers,
Surplus Stock
Information Unlimited - Loads of
interesting gadgets, plans and kits
alt.lasers Newsgroup
- Excellent place to ask questions
sci.optics Newsgroup - Useful Q&A forum