REO Ohmeda Raman Gas Analyzer

So this unit popped up on fleebay for about $125 give or take. Looking a little familiar, it activated my brain a little. I did some looking through the pictures on the auction, and the description, and nothing looked bad. So I forwarded it to Sam, and he confirmed it's uniqueness.

We pulled the trigger, I had it sent to him and some tests were done.

OH NO! No power! What's happening?! Turns out this one was a soft seal and hadn't been run in ages. This meant it had to be run through the gauntlet to tray to get some power back. He ran it for 24/7 for several days:

Sam said:

May 6: 0 uW dim pink/blue
May 7 PM: 19 uW 633 nm dim pink
May 8 AM: 40 uW 633 nm brighter pink
PM: 95 uW 633 nm brighter pink
PM: 110 uW 633 nm brighter pink (Adjusted external mirror.)
May 9 AM: 140 uW 633 nm
PM: 180 uW 633 nm almost normal
May10 AM: 200 uW 633 nm
PM: 235 uW 633 nm
May11 AM: 280 uW 633+640 nm
PM: 313 uW " "
May12 AM: 385 uW " "
PM: 448 uW " "
May13 AM: 578 uW 612,629,633,635,640,650 nm

Click to expand...

Sam said:

*May 16 2013*
It's up to almost 1.2 mW, 5-1/2 lines (640 nm is very weak). But the
really neat thing is that the intensity of the other lines doesn't
differ by that much (probably less than a factor of 2). So, one would expect
633 nm to be far brighter but it isn't. Rather, the 650 nm Raman line -
which isn't a fundamental lasing line at all - is similar or may even
be brighter than 633 nm.

Click to expand...

Finally, we're up to par with what we're looking for here. 1.2mW and 5-6 lines later, we're lasing a wonderful laser.
612, 629, 633, 635, FAINT 640, and 650nm

Though the last hurdle is still one to not underestimate. Seeing them all!
Via regular means, the 629, 633, and 635nm lines all blend to one due to their proximity. I have pictures from Sam depicting it well through his tests, though I am unable to replicate them with my current setup. Jealousy.

SO! You won't get any beamshots, but you do get to see a beautiful laser

Without further adieu, enjoy!





Here you can see the issues that I am faced with when it comes to getting the 629-635 lines to separate. I am going to invest into some decent focal length lenses, and a refraction grating. Should really help out here.




A picture of my output from Sam.


This is his tube:

Excuse my ignorance but what are those tubes near the laser for? (Plastic tubes with a filter on the end? Water cooling?)

Thats quite an extraordinary way to restore the output.. :beer:
Is there any time of the day when you're not hunting wavelengths?

I want to get me a ML HeNe

norbyx said:

Excuse my ignorance but what are those tubes near the laser for? (Plastic tubes with a filter on the end? Water cooling?)

Click to expand...

In my readings I haven't come across anything referencing the tubes. Though, they're connected by a series of valves, so whatever it is, I think it's pressurized. My theory is that it is a direct line to the tube of gas allowing a refilling if necessary (it is a soft seal after all). These aren't your typical tubes at all. REO did some very interesting things. Whereas MG and Uniphase did the standard wavelengths and tube uses, REO was way out in left field doing these sorts of things. Research Electro-Optics = REO.

sinner said:

Thats quite an extraordinary way to restore the output.. :beer:
Is there any time of the day when you're not hunting wavelengths?

Click to expand...

Vigilance Is there? Uh...not really. Hunting wavelengths has, in a way, become an obsession. Even as we were working on this one, I was told of another unit I'd be interested in. Not because it's a new wavelength for me, but because it's class IIIB 612nm. I look at Aryntha as not only an inspiration, but a challenge. Part of my hunting is ego driven, and the other part is just to have a one of a kind. I like exclusive.

Speedy78 said:

I want to get me a ML HeNe

Click to expand...

They're quite joyful once you get them up and running. Talk to Sam, he could hook you up if you really want to go down that road. Although your bank statements may not look to fondly at your decisions

Just about anything from REO is a unique gem all on its own, but this is surely something to make even Aryntha curious. I'll have to stop by Omaha sometime soon to peek at all your unique wavelengths. Not everyone gets to see them like this.

May the pressure go down, and the overall power go up again!

REO is easily my favorite laser producing company. I have plans to get a single window REO, assorted HR mirrors, and a mirror mount. Should be fun

I'll send him a pm/email in the morning, see if he's curious. Though with everything going on, I'm sure he has more to do.

Ha, this isn't too much too look at until I can develop a method of splitting the lines. But let me know if you ever wanna visit! Small dorms though

What are you using to split the beams now? I'm guessing a transmission grating? You might need a mirror grating like they use in monochromators. Iirc lower lines per millimeter will spread the beams more but produce less orders of beams.

I need a diffraction mirror myself for my ML argon, but can't afford one currently.

It's a pretty elaborate setup. That picture was the output going through a reading glass lens, otherwise the divergence is hell.. After lens, to a mirror at a 90* angle, then another, then a diffraction grating.

I'd like a diffraction mirror. I plan to send it through the lens, then mirror, then back through the lens a second time to get the smallest dot size possible. Really the biggest issue is separating 629/633/635. They're just so close that they make a blob, at best, a 3 way venn diagram of sorts.

Any ideas? The pictures Sam took were done via the same method I'm looking to accomplish with the mirror.

Time for some rest, early morning. I'll do some reading tomorrow afternoon for ideas.

My desired end result is having just one spread of beams, and seeing all 5-6 separately. Getting there is the challenge...

You can use an ordinary audio CD's reflective surface to separate the lines. Use multiple CDs in series if the distance required to view the split up is limited.

Meatball said:

You can use an ordinary audio CD's reflective surface to separate the lines. Use multiple CDs in series if the distance required to view the split up is limited.

Click to expand...

I keep getting told that, but all I get from that is a series of actual lines, or crappy looking dots. I can't stand how it looks :/

Need to get a couple helping hands to hold lenses and mirrors.

Silly question, but would a DVD change this effect? I have disks for xbox games and such, but no audio CDs. Don't know if the difference of lines would change anything.

Nah, its the same thing really. Its just the clear plastic on top of a mirror which is doing the work. Maybe a DVD's clear plastic has a better transmission for red WL since DVDs are at ~650-660nm? I know this works well with ML Argons, so it must be an effect of the uW scale you're working with here.

You should see 2-3 sets of the split lines after it hits the CD at an angle - the middle of which should be the most intense. You can further split the lines at a greater angle by aiming the first split set onto another CD at a similar angle. You can do this until you've got an entire semicircle of CDs lined up, each one increasing the angle between wavelengths.

I'll try it with a little patience, might get something working here. I just hate how it looks..

The thing was made in the 80s, looks like a rusted toilet paper roll, and happens to emit very rarely lased photons.

And you hate how it looks.

You should see some of the strange setups I have to put together at work.

"Wait.. its supposed to look like that?"

The output doesn't come out at dots, or if they do, they're very distorted. I was looking for something cleaner. The setup doesn't bother me at all.

I tried the CD trick using blank CD-R's with my ML argon and got huge streaks, not dots, and certainly nothing I would call "lines". I abandoned the idea quickly.

Transmission gratings will work but all make multiple orders of dots and all require a fairly long distance to spread tight wavelengths. For example the 472.6nm and 476.5nm lines on my argon only spread out enough to be differentiated at distances greater than one meter using a 1000lines/mm transmission grating. Using a 500lines/mm grating you can see the lines separate at about 2ft or so. This is of course all for the first order, the second and third order spread out faster.