More Single Brewster HeNe shots! 632.8nm, 611.9nm, 594.1nm and 543.5nm

[ultimatekaiser]

Title says it all! succeeded in very careful, and VERY precise alignment and got some yellow out of my 1-B tube. Also got a proper super-polished red HR for it. Note these beams are NOT fogged.

Output in a clean room is usually 60W+ @ 632.8nm according to MG spec and a little math on my part. losses are likely incurred in my room from dust and possibly some other small factors. the green head is rated for 0.71W

Enjoy! :tinfoil:

Some shots of the tube:

Huge amounts of red!

An amazing amount of orange!

Let's get a close-up of all that yellow!

And a green brewster laser head:

 

[Jstr]

Re: More Single Brewster HeNe shots! 632.8nm and 594.1nm

Nice pics! That yellow is awesome.

 

[Sigurthr]

Re: More Single Brewster HeNe shots! 632.8nm and 594.1nm

Ahh what a beauty! Sam has a 1b tube that is sputter damaged that I'm tempted to experiment with at some point (or turn into a lamp, haha).

Tell me, exactly what are the specs of the mirror you are using the for 594.1nm open cavity emission?

Is this an integral HR or OC brewster, and do you know the specs of the integral mirror? It looks like it is integral HR, but never can be sure sometimes.

Nice find on the super-polished red HR. I want to do similar with a GreNe one day (for ~500mW intracavity 543!) but super polished mirrors are hard to come by.

Btw, got specifics on the adjustable XY mirror mount? I'd like to get one like that eventually. I've been using DIY mounts -_- .

I'm currently buying a 594.1 from Sam (installment payment plan) and asked him about doing an extended cavity. He thinks I'd need to place the HR on the integral HR side though, which is a bit of a bummer since it is a full head and I'd have to pull the end cap off. I may give it a shot on the OC side at some point anyway.

 

[Mattronium]

Re: More Single Brewster HeNe shots! 632.8nm and 594.1nm

Absolutely beautiful :cryyy::cryyy::cryyy:
That intra-cavity beam is neat how it has soo much virtual power and is completely eye safe, granted that the output is <5mW.

 

[ultimatekaiser]

Re: More Single Brewster HeNe shots! 632.8nm and 594.1nm

Ahh what a beauty! Sam has a 1b tube that is sputter damaged that I'm tempted to experiment with at some point (or turn into a lamp, haha).

They're fun, but if you want one, get a nice one. It's worth it.

Tell me, exactly what are the specs of the mirror you are using the for 594.1nm open cavity emission?

Is this an integral HR or OC brewster, and do you know the specs of the integral mirror? It looks like it is integral HR, but never can be sure sometimes.

It's a 5m RoC NOS HR made by MG

Nice find on the super-polished red HR. I want to do similar with a GreNe one day (for ~500mW intracavity 543!) but super polished mirrors are hard to come by.

That is because the super polished mirrors are only made in pairs with the 1-Brewster tubes. You won't find someone who just has one "laying around" generally. They give off a lot more light than a regular HR, & cost about 10 times as much. And green is only possible with a green brewster.

Btw, got specifics on the adjustable XY mirror mount? I'd like to get one like that eventually. I've been using DIY mounts -_- .

Just browse eBay for 2-axis mirror mount. I just use the 1in to 8mm adapter to hold the mirror. They're usually around 30-70$ plus a baseplate.

I'm currently buying a 594.1 from Sam (installment payment plan) and asked him about doing an extended cavity. He thinks I'd need to place the HR on the integral HR side though, which is a bit of a bummer since it is a full head and I'd have to pull the end cap off. I may give it a shot on the OC side at some point anyway.

This would depend on what kind of cavity you would want to make, but yes. This is because the yellow HR quenches red by letting it pass through the HR side on MG tubes. If you add the red back in, you'll just end up killing the yellow though, as the gain of red is around 15x greater per pass.. The OC is specialized for yellow, but it will reflect red too.

 

[Sigurthr]

Re: More Single Brewster HeNe shots! 632.8nm and 594.1nm

They're fun, but if you want one, get a nice one. It's worth it.



It's a 5m RoC NOS HR made by MG



That is because the super polished mirrors are only made in pairs of the Brewster tubes. You won't find someone who just has one "laying around" generally. They give off a lot more light than a regular HR, cost about 10 times as much. And green is only possible with a green brewster.



Just browse eBay for 2-axis mirror mount. I just use the 1in to 12mm adapter to hold the mirror. They're usually around 30-70$ plus a baseplate.



This would depend on what kind of cavity you would want to make, but yes. This is because the yellow HR quenches red by letting it pass through the HR side on MG tubes. If you add the red back in, you'll just end up killing the yellow though, as the gain of red is around 15x greater per pass.. The OC is specialized for yellow, but it will reflect red too.

Re: the sputtered tube. It's damn near free and Sam has no idea how to repair such tubes. I have a theory that depending on the thickness of the sputtered metal I may be able to erode it using localized capacitively coupled plasma. I do want a nice 1B tube eventually though.

It's a 5m RoC NOS HR made by MG

Any specifics on reflectances/transmittances?

Yep, green requires an isotope change. Sam does have a green 1B tube though afaik. I've also read a few places you can squeeze yellow out of green tubes.

Didn't know the super polished mirrors were only made for 2B tubes. That explains the rarity. I would have thought they would be available from major optics places like Edmund for various research applications.

This would depend on what kind of cavity you would want to make, but yes. This is because the yellow HR quenches red by letting it pass through the HR side on MG tubes. If you add the red back in, you'll just end up killing the yellow though, as the gain of red is around 15x greater per pass.. The OC is specialized for yellow, but it will reflect red too.

I was wondering if he thought I had meant a 632 extended cavity when he said that, but wasn't sure. That makes sense. No, I'd be going for a 594.1 extended cavity, much like you did with the 1B.

The end goal would be to attempt a cavity dump one day.

 

[ultimatekaiser]

Re: More Single Brewster HeNe shots! 632.8nm and 594.1nm

Re: the sputtered tube. It's damn near free and Sam has no idea how to repair such tubes. I have a theory that depending on the thickness of the sputtered metal I may be able to erode it using localized capacitively coupled plasma. I do want a nice 1B tube eventually though.

They can't be fixed. the sputtering is on the inside. but you can salvage the window and rinse it with acid to remove the aluminum. Even if it was fixable, then it'd just get dirty again. tubes that sputter usually are doing it because they're end of life. so it'd just gulp more aluminum down the bore eventually again and again more frequently as it ages. It'd be good for parts only.

Any specifics on reflectances/transmittances?

nope.

Yep, green requires an isotope change. Sam does have a green 1B tube though afaik. I've also read a few places you can squeeze yellow out of green tubes.

Well you don't need it...but it helps. he offered me the green tube, but I don't have the money for it atm. sometimes yellow is close enough to be able to get yellow. but that's usually it. The problem is that again...the yellow will take over the cavity, and overtake the green generally.

Didn't know the super polished mirrors were only made for 2B tubes. That explains the rarity. I would have thought they would be available from major optics places like Edmund for various research applications.

Not really. Brewster tubes and their mirrors are not really produced any more. just one in a very long while at request...and they're much more expensive than normal ones. That little tube does 8.2mW+ with a good OC, compared to most others that size are usually more like 2-3mW.

I was wondering if he thought I had meant a 632 extended cavity when he said that, but wasn't sure. That makes sense. No, I'd be going for a 594.1 extended cavity, much like you did with the 1B.

The end goal would be to attempt a cavity dump one day.

Doesn't really work that well. I've tried. The HR lets too little through, and the OC end you lose power from the second mirror surface and the fact that the mirror is concave, so coming at it the other way it's convex...so....it's rather less than effective...scattering it away and not keeping it in the cavity, so it doesn't really amplify at all.

 

[Cyparagon]

Re: More Single Brewster HeNe shots! 632.8nm and 594.1nm

The end goal would be to attempt a cavity dump one day.

11W for 1.7ns (length of the tube)? That's like 18nJ. That's just the light flux though... how much would the plasma energy contribute?

 

[Sigurthr]

Re: More Single Brewster HeNe shots! 632.8nm and 594.1nm

11W for 1.7ns (length of the tube)? That's like 18nJ. That's just the light flux though... how much would the plasma energy contribute?

Ya, it's not like it would be some stellar output. IIRC some university did cavity dumped HeNes and got like 110mW average out, and that was for 632 and probably on a 60W 2B tube.

It would be more for the "neat factor", plus Bloom and I (individually, then later realized we both had the same idea) have had a theory that a mechanical dump system would be possible (read: not optimal, but possible) avoiding the large expense and complexity of a pockel's cell and driver.

 

[ultimatekaiser]

Re: More Single Brewster HeNe shots! 632.8nm and 594.1nm

I was talking with bloom about that a while back too. It would be fun to try

 

[Sigurthr]

Re: More Single Brewster HeNe shots! 632.8nm and 594.1nm

I think the hardest part would be sourcing and mounting the small mirrors in such a way that they don't fly off at high rpm, haha. Conceptually, I can't see why it wouldn't work. We may not get a "beam" of output, but we should still get output, and that is really the only goal.

 

[bloompyle]

Re: More Single Brewster HeNe shots! 632.8nm and 594.1nm

It's nice to see others with similar interests.

It's also nice to see recent 1-B tube work. All previous media is old poor quality photos. something like this is a nice refreshing change to that.

Cavity dumping of a HeNe HAS been done. Using an AOM, a university got something like <10mW average.

 

[Sigurthr]

Re: More Single Brewster HeNe shots! 632.8nm and 594.1nm

Thought so. Doing that does result in a stable output vector, but I think there are large losses in the PBS cube during the quiescent state.

 

[ultimatekaiser]

Re: More Single Brewster HeNe shots! 632.8nm and 594.1nm

They're not huge losses if the alignment is still and spot on. But it does introduce some. Problem is, cost and stability of the surfaces.

 

[bloompyle]

Re: More Single Brewster HeNe shots! 632.8nm and 594.1nm

You get losses from anything in the optical path. PBS elements are not held to the standard 99.999%R that our mirrors are. 99.5-99.9% at best. Same with T, but never both. You generally cannot find a PBS element with HT/HR. 99.95% of one, and 95-98% of the other.

Your main significant loss comes from the electro-optic element. AOMs are slow. You need a fast rise pockel's cell. Something in the <6ns domain. You need an incredible rise time. This is possible from a pockels cell, not even close using an AOM/PCAOM.

That's where their losses came from. Time.

Another problem is the design of the pockels cell. It needs to have brewster windows cut specifically for 632.8nm. Otherwise, it's almost useless.

The perfect setup would include the following, in the order given.

super-polished HR -> 2-B HeNe -> pockels cell -> PBS element -> output.

To the right (or bottom of your screen) after the PBS element would be your second super-polished HR.

You want the PBS element to have focus on the R property. High reflect limits the cavity's transitions from one medium to another, by half (air to glass/glass to glass). A specially made PBS can have an R of 99.95%+ and be of great use. A T of only 95% is fine. 5% losses on ONE passes, versus 5% losses on EVERY pass in the cavity.

Think about it.

It's possible. It truly is possible. With a budget, you can get a specially made pockels cell for the job. Thorlabs has one specifically for something like 680-690nm, that'd be a good place to start. Especially if the inputs are brewster cut. After that, a high rise time driver is also needed. Without a driver capable of getting ~5ns rise times from the cell, it is useless, your cavity is useless, and your entire design will fail. At least gfail to get the desired result. You are in a race against time here. The time between one polarization and another, is light lost in the transition.

It is entirely possible, with the right parts, and budget.

 

[ultimatekaiser]

Re: More Single Brewster HeNe shots! 632.8nm and 594.1nm

Exactly. If everything is Brewster cut appropriately than you actually will have minimal losses everywhere because all the polarizations match with some care... But the cost of all of that...well, it's quite high indeed. Indeed the AOM is the main worry. But all of this would be on the order of several grand new at a minimum.

The sp-127 would be a good candidate for this though.