Alignment help for an SP-107 35 mw He-Ne.

**Eidetic** · 04-20-2010, 19:40

This weekend I'll be doing the same procedure, only using a 10mW cylindrical He-Ne to realign an SP-125 after installing an etalon extension. I don't have the etalon, just want a nicer face on the SP-125 for display. It'll be easier because I'll be starting off with a lasing laser, and will just have to get the OC back in.

**mixedgas** · 04-20-2010, 23:52

alignment..bmp

Pat, he might just get away with the greene, its got the tightest beam, usually, of anything going and its at the peak of the eye's visibility.

From 19 minutes to 26 minutes in this video you can see a alignment setup with the two folded mirrors at 45'. He of course has a megadollar optics setup, you can get away with less. Mentally slide the little sealed mirror hene tube across the table to where it would hit the two mirrors in front of the open mirror hene. Keep in mind that he had to align the tube before the video was shot,,, One thing to remember, you have a heck of a lot more gain then the short tube he uses in the video, your adjustments will be touchy, but not quite as bad as his..

http://www.youtube.com/watch?v=nR0Lm...eature=related

MIT did not put the alignment scene in the clipped Youtube version of Demonstrations of Lasers and Optics, which is a 10 VHS video set with Tunable Dye, Co2, Argon , laser power meters, laser spectrum analysers etc in all their laboratory glory.. One of my mentors was one of Dr Ezekiel's students. I've seen the 3 laser tapes in the set, I wish we could get them on line here.. Have patience, I'm sending you to see the setup, not die of bordom from his slowwww style of talking..

Bob will probably go buy the 4 DVD set..

Steve

**Eidetic** · 04-24-2010, 21:05

I forgot all about this nice blog of the procedure we're discussing here. Enjoy! http://repairfaq.ece.drexel.edu/sam/...ing_SP127.html

**Vidal Wolf** · 04-24-2010, 21:33

Hey robert,
thank you for that link.
that really gave me further clarification and understanding on the proceedure.
I am going to roll up my sleeves and attempt to do it tomorrow.

**mixedgas** · 04-25-2010, 08:40

I see a problem in that picture. You want the 107 on a large stiff, flat, piece of metal, as he is too high in the air for my taste.

I've found more then one large hene mounted on posts in a lab with no crossmembers. The resonator flexes and you end up walking it far too often. One laser was at 100uW when I went to troubleshoot it. It was a foot in the air on 1" posts. Just holding my hand under the frame got them 15 mW. I'd get the alignment system height down. Height means things flex, and this is no time for a limbo contest. I use a cheap but accurate aluminum extrusion under my lasers, its a half I beam known as "association channel" and is readily available, and usually one side is machined flat when you get it. Coherent likes it too, they use it in some medical systems including the 900 series argons.

And if your in a humid place, I'd have methanol besides the acetone. I hate cleaning mirrors with only acetone. And with a durn good reason.

The hepa filter can be a 3M "Filtrete" nanofiber based furnace filter, they are about 9-16$ at home depot. Blow a BIG muffin fan through the filter. If thefiter doesnt cost at least 10$, its not hepa.

Steve

**Eidetic** · 04-25-2010, 09:07

I agree Steve. I've seen holographers mount their he-nes sideways as well, which messes with their air flow and lets them overheat. And I've always been depressed by the use of wood as a structural material amongst them. It goes back to Lloyd Cross in San Francisco in the early '70s at least. I know it can work, but execution plays a bigger role than metal.

**MarioMaster** · 04-25-2010, 12:53

Maybe this will be of some assistance - http://dl.dropbox.com/u/1181169/SP-127.zip

**Vidal Wolf** · 05-01-2010, 14:04

hey guys!.
i started to do the disassembly of the 107 this afternoon. I started by powering it up & looking at the tube. The plasma color being perfect,the getter solid and no degrading of the metal film deposition.
this unit had no boots on it and the brewsters had a thin milky film on the outside of them
it was obvious that these windows were pretty dirty. I took an ordinary q tip and gently and with no pressure on it dragged it across the output side/anode side brewster,and the film of crud came off,i repeated each wipe with a new q tip,still no color tho.
I then turned the head on its side and did the same to the HR brewster and on the *FIRST* pass ,BAM! I got color! just like that!
I was stunned, it was sooo awesome to have it lasing just like that.
I was all ready with the alignment jig,and watched the U tube videos on laser alignment,and read everyones notes and advice. I was a surgeon ready to make the first cut,so to speak, and pow! there it was, all better after barely messing with it.
So I want to thank Mr Robert Hess,Steve,and Pat for the constructive and helpfull advice. You guys are laser gods!