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Old 04-13-2010, 07:29 PM   #323
Darth Avlectus
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Join Date: Dec 2006
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Current Game: Poisoning pigeons in the park.
Most of these I have not done--or shall we say not to a tee as described by the article. Still I find these to be of interesting and pleasant reading.

The Amateur Scientist columns I have obtained on home built lasers from earlier days of Scientific American. Sure people make these things now more moderm, somewhat, but I love the fabulous detailed descriptions and explanations--makes it more fun to read than a technical book at times. Even though the information in some of these pamphlets dates back to 1964. I have articles on the following lasers/packets:

"How a persevering amateur can construct a Gas laser in the home"
Original gas laser using Helium Neon (HeNe) had been developed for amateur level/skill construction. What makes this so much more interesting is:
1) how you yourself get to construct the discharge tube by glass blowing and working, and the importance of the work of Sir (David?) Brewster in optics as you have to incorporate it for maximum efficiency of the optics in your system using Brewster angle windows at both ends.
2) making your own vacuum system and mercury manometer--this alone is a science in itself
3) making the support frame for the assembly of the entire thing--a good exercise in machine shop fabrications
4) Intricacies of every aspect of making one of these things work I.E. Considerations for the power supply and whether or not to operate it high or low frequency as well as AC or DC (I always thought beforehand that gas lasers were DC), perfecting the gas mixture for lasing, creating "Getters" as purging elements to excise contaminants in the operation setup, the shop cleanliness practices, and final alignment of the resonator mirrors.
Also, for anyone who knows about laser resonators, you know that the pair of facing mirrors for the resonator must be as perfectly close to parallel as possible--you must use special mounts to put the HeNe laser mirrors into in order to achieve this perfection.
This laser outputs an orange-red beam @ 6328 Angstroms or ~633 nanometers.

"How to construct an Argon Gas laser with outputs at several wavelengths"
Very similar design to the above, this article teaches you how to build a (very crude) argon gas laser. Except the gas system has more requirements, the mirror mounts and adjustments are a little more sophisticated.

Lastly you have a similar power supply but what is different is the gas requires a much higher initial voltage potential to start the breakdown into ionization. In this particular case it utilizes an RF (Radio Frequency) field via an "Oudin coil" like the kind used to test glass parts of vacuum systems for leaks. This means it creates the high potential field around the tube and ignites the gas without any physical contact whatsoever. Similarly to some strobe lights where you see the small thin wire around the lamp itself. Since I think this acts like a sensor (it's a parasitic oscillator of the main filter capacitor, yes a simple inductor-capacitor oscillator) it probably cuts off when the main sustaining discharge levels take over.

This "ancient" design, I am not sure in what way it would self destruct because there are so many ways. Off hand, I'd say compromised seals of the electrodes if not outright discoloration and deformation due to overheating making it unusable. Another one is ablation of miniature irregularities that may be present on a microscopic level inside the tube. The arc will chew and drill away at it until the tube has been compromised and you have a leak.

A side word if you think you can keep up with relatively minor comparisons between different Argon laser power supplies:
Show spoiler

Lastly, the most fun part is by different current input levels, you can control the (color) frequency of the output. It has green, cyan, blue, indigo and violet discharge outputs.



Right now I don't feel like giving detailed reports of the next 3 laser data packets but I'll give you a preview of what's coming up next:

A homemade Mercury-Vapor Ion laser that emits both green and Red-Orange
The first gaseous ion vapor laser that has an unusual characteristic of simultaneous emission of two different wavelengths.

"An unusual kind of gas laser that puts out pulses in the Ultraviolet"
(My senior project in high school! ) This is by far the simplest laser project of the bunch and requires nothing fancy, but its design can be a pain if certain considerations are not taken.

"A Carbon Dioxide laser is constructed by a High School Student in California"
A high power output infrared laser outputting several watts that can burn and cut many materials. I'm actually working on a similar but much more modern design--admittedly more cookbook style with much of it already pre-made because I'd like something more powerful and more useful than just for display. However the principle is much the same.


We'll murder them all, amid laughter and merriment...except for the few we take home to experiment!

"I cant see S***! --YOU GO TO HELL!" --Tourettes guy
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