HeNe laser tube identification please

[holocyware]

Howdy,

I have found this laser tube and I'm wondering about the specs (power etc). If anyone can identify it please do.

It may be a russian tube, and it's about 6" in lenght/2" diam. What would be the maximum obtainable power with this size? It looks like the longer the tube, the higher the power. I'd expect something like 1-3 mW but I'm looking for expert opinions.

thanks

 

[HIMNL9]

I seen something similar years ago in an electronic fair, but also the seller was not knowing from where they came (salvaged / recovered parts)

It look as a He-Ne cavity with external mirrors and Brewster windows directly "glued" on the tube ..... if so, try first with a PSU for a 5mW if it still light, cause the helium contained in these "glued windows" units, with the years, tend to lost through the glue assembly (intrinsec porosity, He atoms are small enough for pass through them) ..... if so, there is the possibility that, for make it work again, you need to refill it (if it have enough years, ofcourse)

Anyway, it looks in good conditions, from the pics.

 

[daguin]

That is a nice find even if it doesn't lase (or even give you a plasma).

If you can't get it to light, I'll trade you a working one (with PSU) for it just to set it on the shelf in my tube collection display.

It's cool looking

Peace,
dave

 

[Cyparagon]

That's a lot of heat sinking for a HeNe, dontcha think?

 

[ElektroFreak]

It could be something other than a HeNe, but I don't know what. It has the can style cathode of a HeNe.. and every HeNe I've owned gets pretty hot after awhile (not like an argon, but still pretty hot).

 

[Cyparagon]

Hot enough to require heat sinks? I've never seen a HeNe with heat sinks before.

 

[HIMNL9]

Uhm, maybe, it depend from the power ..... from the pics, i cannot say for sure, but the rear mirror is bigger than any other i've seen on He-Ne units, and at first sight, also the "capillar" tube looks "huge", and all the unit is compact, for that capillar tube size ..... wondering what really was the power.

Other than this, it look as a closed unit ..... maybe, if it had to work continuously, it can become more hot of normal ones .....

 

[Cyparagon]

You can't increase the current on HeNes to get more power like you can on most other lasers. I'm not sure why, but it just doesn't work that way. If you want more power, you need a longer tube. And as such, the operating temperature is roughly the same for all different powers.

 

[HIMNL9]

^ yes, cause the efficency of most of the gas lasers is in part a function of the lenght of the cavity, and part about the diameter of the beam (sorry, don't know how to say it more technically )

But considerate that also the surface of the cathode have part in the temperature dissipation, and that one looks big ..... other than this, as i've said, the tube is enclosed in a second tube ..... in closed tubes, the external metal tube is usually glued to the glass tube, increasing the dissipation, but not in this one, so it probably need to be more dissipated inside ..... also, note that the alignment of the tube is made with these big screws that are in the dissipator (the 8 screws placed in 2 rings of 4, at cross, are the ones that hold the tube in the dissipator and that change its alignment) ..... so, the other possibility is that is not finned for cool the tube, but for keep cooled the aluminium tube itself, for minimize the disalignment due to temperature change (any metals, more or less, change shape with thermic variations, and cause the alignment screws are in that tube, is possible that, if it become too hot, it disalign the inside tube)

Other than this ..... it's just a personal impression, or the angle of these Brewster windows is a bit different than the ones of red lasers ? ..... i mean, i can be in error, cause i only have this pic to see, but these windows looks like 30 degrees ..... and usually the different colors of the He-Ne lasers are obtained with different inclinations of these windows ..... but may also depend from what material is used for the windows, so it may also means nothing

 

[ElektroFreak]

Uhm, maybe, it depend from the power ..... from the pics, i cannot say for sure, but the rear mirror is bigger than any other i've seen on He-Ne units, and at first sight, also the "capillar" tube looks "huge", and all the unit is compact, for that capillar tube size ..... wondering what really was the power.

Other than this, it look as a closed unit ..... maybe, if it had to work continuously, it can become more hot of normal ones .....

A larger bore will result in multimode operation. This in turn allows for more power output from a short cavity. Perhaps enough extra power to require heatsinking..

 

[diachi]

A larger bore will result in multimode operation. This in turn allows for more power output from a short cavity. Perhaps enough extra power to require heatsinking..

The problem with HeNes is that the bore cannot exceed a certain size otherwise efficiency lessens. HeNe lasers rely on the atoms of the gas colliding with the walls of the bore, if the bore is too big this doesn't happen enough to create good gain in the cavity. That's why to get 50-100mW from a HeNe you need a tube that's 5ft long

 

[ElektroFreak]

To have a single-mode 50-100mW HeNe requires a 5ft tube.

Just the fact that I've never actually seen a multi-mode HeNe doesn't allow me to count it out.. After all, the same rules apply to HeNes that apply to all other lasers. It would be theoretically possible to have a multi-mode HeNe, expecially when you take into account the fact that all lasers are inherently multi-mode. They need special design tweaks to get them to run single mode TEM00 (such as a precise bore size in gas lasers). Also, less efficiency doesn't block operation. A HeNe tube with a larger bore could still work even though it is less efficient. Efficiency is lost on lasers for the most part anyway..

Really, though, the person to ask is Steve (mixedgas) over on photonlexicon.com. He would know better than any of us.

 

[Gryphon]

I dunno, but that last pic kinda reminds me of a lightsaber