Lasers, Comments & Links


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

Home Made Laser Page 1
Home Made Laser Page 2
Home Made Laser Page 3
Home Made Laser Page 4
Home Made Laser Page 5

alt.lasers Newsgroup - Excellent place to ask questions
sci.optics Newsgroup - Useful Q&A forum

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