HeNe tube mod concepts. (may be good for your daily LOL if nothing else)

[psi seeker 34]

I have several concepts for moding my HeNe tube however I'm not sure if they are worth doing or if they would work at all.

So I'm posting my concepts/questions on these mods and I would like the advice on these concepts answered in the following order if possible ,(A) would it be possible? , (B) is it worth doing?, (C) if it's possible and or worth doing what is the best way to attempt such a feat ?,

Mod #1 this tube has 2 semi reflective mirrors in it one of them is less reflective than the other. The question is will a common slivered mirror be good enough to supplement one of these other mirrors well enough to increase the output power of the laser itself and can this be done without removing one of the existing mirrors?

Mod #2 Provided the proper equipment is available can the gas inside the tube be exchanged for a different mixture of gasses in order to change the output color? If so what color/s other than the current is most compatible with the existing mirrors? (my tube currently emits a pinkish orange)

Mod #3 If the tube breaks for any reason can the mirrors be removed without breaking them? If so what can they be used for?

Mod #4 Is it remotely possible to exchange/replace the existing mirrors (built in type) without wrecking the tube too bad to be repaired with amateur glass blowing skills , the proper gas mixture, and a vacuum pump.

 

[daguin]

I have several concepts for moding my HeNe tube however I'm not sure if they are worth doing or if they would work at all.

So I'm posting my concepts/questions on these mods and I would like the advice on these concepts answered in the following order if possible ,(A) would it be possible? , (B) is it worth doing?, (C) if it's possible and or worth doing what is the best way to attempt such a feat ?,

Mod #1 this tube has 2 semi reflective mirrors in it one of them is less reflective than the other. The question is will a common slivered mirror be good enough to supplement one of these other mirrors well enough to increase the output power of the laser itself and can this be done without removing one of the existing mirrors?

Mod #2 Provided the proper equipment is available can the gas inside the tube be exchanged for a different mixture of gasses in order to change the output color? If so what color/s other than the current is most compatible with the existing mirrors? (my tube currently emits a pinkish orange)

Mod #3 If the tube breaks for any reason can the mirrors be removed without breaking them? If so what can they be used for?

Mod #4 Is it remotely possible to exchange/replace the existing mirrors (built in type) without wrecking the tube too bad to be repaired with amateur glass blowing skills , the proper gas mixture, and a vacuum pump.

For the "average" hobbyist:
1 = No
2 = No
3 = They can be "removed" but will have little value for you
4 = No

Peace,
dave

 

[aryntha]

A vet can correct me if I'm wrong here - but, PsiSeeker - with HeNe, the color of the output is not simply a function of the gas mixture alone.

Specialized optics -i.e., mirrors created for and tuned for the desired output wavelength, have to work in conjunction with the lasing lines available in the tube to produce a desired output.

For the most part, for example, green, red, orange and yellow HeNe tubes have the same gas mixture inside; it's the optics that determine the lasing action and which line gets amplified and produced.

So to change to a different output color you'd need to affix new mirrors - not something that seems worth it. (Though when I had that dead 612, some pros did want those mirrors... - Probably for an external mirror tube; I can't imagine anyone trying to build their own 612 HeNe ...)

 

[HIMNL9]

Yes ..... basically, due also to the low efficency of the tubes, if you want to change the color of a He-Ne tube from, say, red to green, you need at least, for get the maximum possible green output, to:

Change the "cavity" lenght, for match the new wavelenght (professional assemblies)

Change the mirrors, IF they are multilayer dielectric ones, with a pair of them that have the "layers" matched for the new wavelenght

Change the angle of the Brewsted window (or windows, if the tube have two of them), with a different angle that match the new wavelenght

..... this as basical modifications

 

[psi seeker 34]

I had no idea that it would take that much work to alter a HeNe tube.

Ok so what changes if any can be reasonably done to a HeNe tube that has internal
optics (no brewster window) ?

 

[aryntha]

I had no idea that it would take that much work to alter a HeNe tube.

Ok so what changes if any can be reasonably done to a HeNe tube that has internal
optics (no brewster window) ?

Sometimes you can put magnets around them to get a stronger or more stable beam. I don't want to pretend to know how this works, but I think it has something to do with attenuating one of the IR lines.

 

[Eidetic]

I had no idea that it would take that much work to alter a HeNe tube.

Ok so what changes if any can be reasonably done to a HeNe tube that has internal
optics (no brewster window) ?

Nothing. You can build it in to something sculptural, like a lamp base or table top. Steampunk.

 

[Xplorer877]

You're thinking of High Voltage tubes. Changing the gas mixture and pressure will affect the color of HV streamers in said environment. But even though laser tubes use HV it is not the color of the plasma that dictates the color to the laser output. For example; green HeNe tubes glow a pale red yet emit a green beam.

See;

-Dave's pic-

-Tony

 

[Seoul_lasers]

a very pretty desklamp !

Too bad gas lasers are in many ways on their way out, other than CO2
I really wished someone could come up with a TEA He/Ne laser for more power, if it could be possible.

 

[psi seeker 34]

I prefer gas lasers for 2 reasons, 1 in addition to a laser you also get a neon lightbulb
and 2 it's remarkably hard to break them due to adding too much power.

 

[Seoul_lasers]

I prefer gas lasers for 2 reasons, 1 in addition to a laser you also get a neon lightbulb
and 2 it's remarkably hard to break them due to adding too much power.

True. You can't break them by a little bit too much current.

 

[LSRFAQ]

I have the facilities to mod them. I'll do anything you'd like, at 400$ a hour plus parts cost. Minimum 8 hours.

Why so expensive, because the tank of ultra pure gas alone is 270$ plus hazmat shipping. The pinchoff tool was 1800$. A pound of the helium proof glass is about 250$. The bore in one offs is 30$. The optics, if in stock, are 250$ a piece for one offs, and about 15$ a set if you buy 2000 sets.

Its expensive... get the idea? Better just to buy one already made, because when made in bulk, they are cheap.

I'm not kidding, at 400$ a hour I'm letting you off light. Hiring the glassblower, if needed is 100$ a hour.

Now if someone wanted a 300 mW vfold hene, I could do that at a bit cheaper rate. They have been done. Its not hard. Just the beam is fat in one axis.

In reality, I rework a few Coherent Inc, argon ion tubes per year. I can do anything you'd want with a ion, cheaper, faster and easier, and have more wavelengths to choose from. Including 13 line whitelights.

I got lucky, I had a investor buy me the pinchoff tool and most of the vacuum station. He needs a few custom modified ion lasers per year, and let me keep the supplies in return for researching how to do it.

There are plans in Scientific American for home made henes.

I know of a few folks who have done it:

Take a look at pulslaser.de

Then take a look at this:

http://www.jklasers.com/HeNe/HeNe_Laser_Report.htm

HENE is difficult, a fraction of a fingerprint in the wrong place, inside the vacuum system, or the smallest amount of oxygen, stops lasing.

They will probably never quite go away for the next 50 years, as they are the secondary standard for the meter for most countries.

The good news is you can make a nitrogen laser, its much easier, often works with plain air, can be done on a kitchen table, and in many ways, more fun. No exotic parts, either. Once you get N2 going, you can generate just about any color you want with a dye pumped by the N2 laser. Plans are freely available and I'd be shocked if the materials cost is more then 50-100$, provided you know how to scrounge. Youtube videos are all over the place.

I have a commercial, used, N2, it does 100-150 Kilowatt, peak power, pulses at 20 hz. It has no trouble pumping Rhodamine dye. its not for sale.

I also have a 1 brewster hene tube setting here if you want to play without cracking the glass. I paid 75$ for it and a power supply. Let me know if you really, really, really want it and I'll see if its in good condition. The mirror inside will allow 615, 640, 633, and some of the rare oranges to lase as well as the Raman red line. I think Sam got a little,, ie microwatts, of 584 yellow from the same type.

Until them I suggest you read:

Sam's Laser FAQ - Helium-Neon Lasers

and the external mirror trick:

Sam's Laser FAQ - Helium-Neon Lasers

I do know a fellow who got yellow from a green tube without changing mirrors, using the external mirror trick.

And if Daguin is bored, I have gotten other lines from single line air cooled, sealed mirror argons. Hint, Hint.



Steve

 

[psi seeker 34]

Cool !!!!

How much would it cost if I wanted to have my HeNe filled with the gas mixture they often put in Co2 lasers ?

 

[LSRFAQ]

Cool !!!!

How much would it cost if I wanted to have my HeNe filled with the gas mixture they often put in Co2 lasers ?

171$ plus shipping.

Already done and on ebay, 171$:

NEW 40W CO2 LASER TUBE CUTTING ENGRAVING WATER-COOLED - eBay (item 370395525294 end time Jul-12-10 06:03:13 PDT)

HENE mirrors have a coefficient of expansion of 32 x 10-7 cm per degree C of temperature change. The Kovar metal the mirrors and tube glass are hard sealed to has a expansion of 34 x 10=7 cm/deg.

The Zinc selenide used in small co2 optics has a COE of 6 x 10-7 cm/deg, your metal has to match your mirror material within 6 parts per million. So it cannot be done. Your 26 off on the COE.

The gas again, would cost me about 300$ and shipping. The fill tube, made of nickle, about 20$. The real issue is the bore size is way too small for Co2, you'd get a pretty bluish white glow, but no lasing.

Steve