Another broken laser - HeNe 612nm. Tube lights fine.. but

[daguin]

As far as the plasma goes - you can tell the mirrors are out of alignment by that?

Peace,
dave

 

[lasersbee]

He did not state 'as is'. He stated, "Well preserved, no damages." However, the seller has not been communicative so far , early on when I asked him right out if it worked or not.

As far as the plasma goes - you can tell the mirrors are out of alignment by that?

If there is strong plasma in the capillary...It would seem that you should
have lasing... IF the mirrors were aligned properly... Even a faint beam...
I'm speaking of some small experience with 5mW HeNe... maybe 612nm is
different...

We haven't seen your Laser up close... so we can't know what actual
color your plasma is... look at the Graph Dave posted.. it should give
you an idea...

Then open as PayPal Dispute....



Jerry

 

[aryntha]

The plasma color really does look 'normal'.

No lasing...

I've opened up a paypal dispute now.

 

[aryntha]

Checking with diffraction grating (looking at the 'lines' from the plasma discharge) -- all of the lines in the "Normal" diagram seem to be there - and it does appear to be that color; so I'm guessing this is not a gas issue.

I've poked and prodded at the mirrors to no avail; but there are these odd circular metal rings around each collar secured by 3 hex screws each; not sure what purpose they serve.

So I'm still betting on mirrors (not sure how that could have happened) but, folks say its 'hard' to realign these but not impossible... Is it 'difficult enough to be effectively impossible" ?

Anyways, have had it running for about 1 hour now and still nothing but blue noncoherent emission from the front...

 

[MarioMaster]

Checking with diffraction grating (looking at the 'lines' from the plasma discharge) -- all of the lines in the "Normal" diagram seem to be there - and it does appear to be that color; so I'm guessing this is not a gas issue.

I've poked and prodded at the mirrors to no avail; but there are these odd circular metal rings around each collar secured by 3 hex screws each; not sure what purpose they serve.

So I'm still betting on mirrors (not sure how that could have happened) but, folks say its 'hard' to realign these but not impossible... Is it 'difficult enough to be effectively impossible" ?

Anyways, have had it running for about 1 hour now and still nothing but blue noncoherent emission from the front...

Those rings are called locking collars, designed to prevent the tube from being knocked out of alignment.

 

[Solonar]

I can give you some information on aligning the mirrors when I get home. I've aligned thousands of those lasers.

 

[daguin]

So I'm still betting on mirrors (not sure how that could have happened) but, folks say its 'hard' to realign these but not impossible... Is it 'difficult enough to be effectively impossible" ?

You've got to be "lucky."

Do you feel lucky?


Well do ya? :na:

I can give you some information on aligning the mirrors when I get home. I've aligned thousands of those lasers.

< waits with anticipation >

Peace,
dave

 

[aryntha]

You've got to be "lucky." Do you feel lucky? Well do ya? :na:

After this week, two dead gas lasers in a row - hell no!

Those rings are called locking collars, designed to prevent the tube from being knocked out of alignment.

....sounds promising?

I can give you some information on aligning the mirrors when I get home. I've aligned thousands of those lasers.

... PLEASE let this be possible... If I could get a working 612nm out of this, I'm going to have to send some people some beer. (Not the seller.) Sam Goldwasser said there 'may still be hope yet'... so, I'll await your response

 

[daguin]

As long as there is good plasma, there is hope

I have a small green here that I refuse to give up on

Peace,
dave

 

[timelablasers]

Hi,
I have a Melles Griot head that has the same tube in it with the same wavelength. I too purchased mine from an ebay seller years ago who said it worked perfectly and when it arrived, it didn't. What I did was out of sheer frustration tapped the head with a screwdriver and ta dah!.....it worked and has worked ever since.
It may have worked for the seller too. Unfortunately, postal workers have a lot to answer for. Parcels get put through the mincer. Your laser may have been dropped or even thrown which was enough to knock the mirrors out of alignment. You can try what I did but no guarantees of course.
What did that laser set you back anyway?
Cheers,
Rob.

 

[aryntha]

Rob,

$300 or so. (And out of sheer frustration, at this point in the game I'd pay more than that for a working 612nm.)

At this rate, in finding a 612nm, I had to take that chance.. (And lost...) I've been tapping all about the mirror mounts - I assume you mean you just tapped the casing itself with a screwdriver and you were good?

Unfortunately I think we're way beyond that at this point :\ I'm hoping we hear from the guy who says he's aligned lots of these.

 

[Solonar]

First, the locking ring is also how the optics are adjusted, the allen set screw go into a groove that, when the screw is turned in, will cause the optics to tilt slightly.

Second, you will need some kind of filter, as you need to look down the bore while the laser is lit. We used small 1" square green filters mounted in a plastic end cap when I worked at melles griot. You will also need an insulated allen wrench of the appropriate size( my tubes use 3/32", though they may have gone metric in 20 yrs)

Now you will need to use the filter to look down the bore of the powered laser, Ideally you should look through the output end first. You should see something like my first drawing(if so, the HR mirror is nearly perfectly aligned)
If you see something like the second drawing, you will need to loosen the 3 set screws and rotate the collar until 1 screw is on the same side and in line with the spot. Slowly tighten the set screw until you see the spot start to move. Ideally you want the spot back int the center, but depending upon what happened to cause the misalignment, that may not be possible, But the tube will still lase with a slightly misaligned spot just at a reduced power.

repeat for the OC mirror. Then snug up the other setscrews without moving the spot and put some loctite on the screws to keep them from loosening.

Once both spots are mostly centered you should have a beam. If you have an LPM, you can fine tune from there.

 

[aryntha]

This is worth a try -- thanks, it may work.. Would red laser goggles work OK too?

-- Also, I'm surprised you can see the other mirror through the plasma glow? Am I possibly looking at the wrong thing?

 

[Solonar]

This is worth a try -- thanks, it may work.. Would red laser goggles work OK too?

-- Also, I'm surprised you can see the other mirror through the plasma glow? Am I possibly looking at the wrong thing?

As long as the OD is ~2-4 they should work. You need enough filtering to blockout the majority of the plasma glow, but not too much.

The process is actually pretty simple, but hard to describe. I aligned several hundred a day for 15 months when I worked at MG.

Make sure you use an INSULATED wrench, especially on the anode end(dont need any unnecessary shocks)

 

[aryntha]

Yeah I actually have an insulated hex wrench -- and was just working on it; I guess my issue is, I'm not sure if I can even see the mirror.

More and more makes me feel that this was knocked out of alignment (on the HR side) for the following reasons;

1- The HR collar adjustment collar was actually -loose-.
2- In shipping, the power 'brick' had come loose and was hitting the HR collar.
3- The blue output from the laser (when shined against a piece if paper) looks like this: (Done in photoshop, but it looks almost exactly like this.)

... I have a feeling that just tweaking those screws, it's not going to come back into alignment, no matter what I do.

 

[Solonar]

Sure it will, actually knocking them completely out would most likely kill the tube. If the collar was loose, that is the most likely mirror out of adjustment. I didn't see anything in your pictures that would indicate an impossible realignment.

If you see comething in the bore like your drawing, I would start by adjusting a screw on the bottom. Just a bit to see if the spot moves. Unfortunately not all ppl recognize the spot in the plasma without training. Some of the ppl I had working for me took weeks to finally catch the trick. Some ppl catch it the first time. If I can get my camera to focus down the bore with a filter attached I will do a video.

Unfortunately I was in the emergency room with my mother tonight, which is what took me so long to post. I will try to get a video tomorrow sometime.