Convert a red HeNe to yellow

[DJZ]

I've always wanted to play around with HeNe optics to see if I could get something other than red from one. I recently noticed that Sam G. sells HeNe optics of various colors on eBay so I figured I'd give it a shot. I ordered up a set of yellow HeNe optics and spent hours trying to get yellow from a Spectra Physics 127 while at SELEM. Unfortunately it didn't work out, no luck at all.

I tried again this past weekend with a Spectra Physics 124 and finally had success! I would guesstimate that it's only doing 1mW but that's enough for me.

For the HeNe, power supply and optics I think it all cost me right at $150.

 

[Alaskan]

How did the optics produce yellow? i'm not tracking how yet, very cool.

 

[FRITZ HID]

Awesome!

i was thinking of trying that with my 127b but will have to wait till i can get a stable base to work on, everything here shakes too much for optics! lol

what exactly is the diff between your 127 & 124 that allowed yellow?

 

[diachi]

How did the optics produce yellow? i'm not tracking how yet, very cool.

Sounds like he used optics for yellow instead of optics for red.

Depends on the tube, sometimes you can keep the existing optics on there and still get yellow, only option with an internal mirror tube. External mirror tubes make life easier as you can just swap the existing mirrors.

IIRC gas pressure has an effect too.

 

[paul1598419]

Yeah, I've seen this done before. It is pretty touchy to get the alignment correct. External mirrors is always the easiest and best way to go.

 

[ultimatekaiser]

How much red does the tube do? I've not personally tried this yet with mine. I can't imagine it would do a ton, but 1mW isn't terrible. In theory it could do more than 5 if it was optimized correctly. They're quite long. Also welcome to the 124 club, there's not many of these that still work. I was starting to think me and Phil had the only last ones that still work. Also, I assume you used some of Sam's mirrors for this. you also might have better luck using the anode end of the tube for output it tends to work better. have you tried that?

 

[icecruncher]

I've always wanted to play around with HeNe optics to see if I could get something other than red from one. I recently noticed that Sam G. sells HeNe optics of various colors on eBay so I figured I'd give it a shot. I ordered up a set of yellow HeNe optics and spent hours trying to get yellow from a Spectra Physics 127 while at SELEM. Unfortunately it didn't work out, no luck at all.

I tried again this past weekend with a Spectra Physics 124 and finally had success! I would guesstimate that it's only doing 1mW but that's enough for me.

For the HeNe, power supply and optics I think it all cost me right at $150.

Glad you finally got it going. I was really hoping to see it at SELEM.

As already asked, why the success with the 124 and not the 127

And 1mw seems low ??? You were looking for 15 mw or so, if I remember correctly, from the 127. Any reason on this??


I always get the 124 and 125 mixed up.

125 is the one I never have seen a working one of... I'm sure there is one somewhere

 

[ultimatekaiser]

the 124 is 70cm (rated >15mW red)
the 127 is just shy of 1m (rated >35mW)
the 125 is about 2m and is a cheater-it's technically 2 tubes end to end sharing a common cathode (or RF excited by option, and rated >50mW)

the 124 is easier to do experiments with due to a lot of optics being <1m radius of curvature and the typical HeNe resonator is long radius design-usually concave OC and planar HR. Power on lines other than red is limited due to the tubes being filled to be red efficient. the other lines require different pressures and gas mixes to reach maximum power. The 124 was made to do red or IR by request. the other lines weren't really ever used back then. by the time those other lines were being discovered and applied, hard sealed, low cost tubes that we use today were already commonplace and the external tubes were on their way out-about the early 80s. It'd do alot more of the other colors if the pressure and mirrors were optimized for it, but that'd cost thousands of dollars to do.

 

[icecruncher]

I guess what I should have said was...

i get confused and I always think of the 125 when people start talking about the 124.

But a quick question

I know the 127 is hard sealed and the 125 is soft seal

what about the 124? I'm guessing soft seal, especially with the comments about not finding people who have working ones, but I'm not sure.

If it is softseal, I would think it might make a difference in tube fill ratios over time, to make certain 124 tubes either easier or harder to get an exotic color, like yellow, out of it as compared with the 127.

But, I'm just making an educated guess.

the 124 is 70cm (rated >15mW red)
the 127 is just shy of 1m (rated >35mW)
the 125 is about 2m and is a cheater-it's technically 2 tubes end to end sharing a common cathode (or RF excited by option, and rated >50mW)

the 124 is easier to do experiments with due to a lot of optics being <1m radius of curvature and the typical HeNe resonator is long radius design-usually concave OC and planar HR. Power on lines other than red is limited due to the tubes being filled to be red efficient. the other lines require different pressures and gas mixes to reach maximum power. The 124 was made to do red or IR by request. the other lines weren't really ever used back then. by the time those other lines were being discovered and applied, hard sealed, low cost tubes that we use today were already commonplace and the external tubes were on their way out-about the early 80s. It'd do alot more of the other colors if the pressure and mirrors were optimized for it, but that'd cost thousands of dollars to do.

 

[ultimatekaiser]

they were only made with the red standard fill. all of them. some came with the option for IR mirrors at extra cost in addition to red ones. they're all softseal except the 127. but a truely optimized IR one could be done at request. and orange was briefly offered then discontinued. yellow and green were not offered until much later and only in hard seal tubes. helium loss would've killed those even faster than the red ones and were far more touchy and expensive to produce.

 

[CynicalBrad]

Neat conversion. +REP

 

[icecruncher]

they were only made with the red standard fill. all of them. some came with the option for IR mirrors at extra cost in addition to red ones. they're all softseal except the 127. but a truely optimized IR one could be done at request. and orange was briefly offered then discontinued. yellow and green were not offered until much later and only in hard seal tubes. helium loss would've killed those even faster than the red ones and were far more touchy and expensive to produce.

I don't know enough about gas fills, thank you

Still cool to see yellow from a large frame laser.

DJZ, may you can bring it to the next SELEM with the yellow???

 

[LSRFAQ]

I arranged for DZ to have a sweet little box of optics at SELEM.
Don't want to steal his thunder, so stay tuned.

Did see two line operation at one time while at SELEM.

Steve

 

[paul1598419]

That was very generous of you, Steve. Will be looking forward to what DJZ is able to do with them. + Rep.

 

[MarioMaster]

I figured I would bump this thread, DJZ spent a bunch of time at SELEM 2018 playing musical mirrors with my SP-127 and was able to get orange out of the tube. The SP-127 is now his and hopefully he will update this thread with his new findings

 

[kecked]

Was fun to watch. DZ in the sandbox. He got a flash of green I think as well.