MI-Lasers 543 bare tube!!![pics]

543 bare tube beauty!

I FINALLY got around to wiring up and firing up my 19 inch bare tube 543. There is a thread from about a year ago when these went on sale for around $95.
I've been staring at the postage box with the tube and the wall wart that is perfect for the PS for months now. Just last week i ordered the PS, Alden cables, and tube mounts.
I didn't have any experience with wiring up tubes before, my other gas is a 30mw argon that was ready to roll when i got it.
The 4 second delay on the power supply almost had me in tears, then BOOM! Glorious 543 yellow green light. Enough blabbing. Pictures!


yes i still own a globe, i know there is an app for that


Thanks for looking!

Very nice! I love the long glowing bore of these lasers :beer:

I got one of them also, they are beautiful! its really cool seeing a red plasma with a green or yellow beam coming out

And they will last a Long Long time. IIRC its in the 10s of thousands of hours.

Have fun.

AWESOME! the purple hue inside the cathode bore is very interesting... any info on that?

The reddish hue you see looking in through the mirrors is the dielectric coatings. Orange HRs are purple while the OC passes blue, the green mirrors pass red light, and yellow/red mirror sets pass blue light.

The bore plasma should be kind of a salmon color.

How much power is it? I think they're rated for 2mW?

Yeah the handwritten spec sheet(which is awesome) says 2.1mw. This WL is so much brighter than any other I have for the power.
Ps thx uk

Yeah..per mW I'd say its among the brightest. I've used mine as a telescope guide before, it works great. I've got a melles griot 05-LGR-193 that does 4.2mW, But it's rated for 1.5mW. It's very bright for a class IIIa! I think those bares from MI are the same MG tubes (the 192). Let it run for 20 minutes then meter it. And keep an eye on it...new tubes, and especially non-red tubes, have a habit of losing power as they sit, the He loves pressing to the walls. So if you run it regularly for maybe an hour each day, in coming weeks, you may see the power rise up a bit as the gas begins circulating again. Also try rotating it as it runs-Power may fluctuate a bit as gravity pulls on the bore, though in this case probably not as it has glass bore supports, not metal.

yeah its the mg 192, i usually run it for at least 3 hours at a time through my lumia set up. and i have been spinning it regularly. And i have noticed a power increase. pretty sweet to have an artificial aurora in my room at all times ill LPM it soon and give you and update.
also... what is the preferred solution for cleaning smudges off of it?

Well typical lab cleaning (what I do) is reagent 99.9% grade acetone and lens cotton/tissue. But a bit of 90% isopropyl alcohol and a cotton swab should do just fine I don't think it'll harm the coatings. Just be super gentle or you'll scratch the AR coating on the outside of the mirror.

I've seen one of those HeNe's slowly loose output until it dropped to 0mW due to a low-wattage ballast resistor... as the resistor heats up the current flow to the tube increases, which actually DECREASES output

That's true of all HeNes hwang. That's why it's important to run it at spec with proper ballast. 75K within 2-3 inches of the anode is generally enough for most tubes, though some larger ones we use a bit more. And little ones like the mini 6" tubes we use 68Ks

by within 2-3 inches, do you mean it can be closer than that? or is 2-3 inches the ideal range? mine is soldered directly to the clip with about an inch of clearance

That's fine. It just has to be close enough to the tube so that it can do its job. it limits the flow, but it also stifles interference and oscillations and such, so if its too far away it won't do its job. mine is soldered directly to the clip as well on a couple of my Alden cables for some extra rigidity.

bdgreenb said:

also... what is the preferred solution for cleaning smudges off of it?

Click to expand...

Were you talking optics or just the glass tube?

My understanding was 99.9% Methanol was better for cleaning the optics - but I could be wrong

The tube itself shouldn't be a problem with whatever you use.

icecruncher said:

Were you talking optics or just the glass tube?

My understanding was 99.9% Methanol was better for cleaning the optics - but I could be wrong

The tube itself shouldn't be a problem with whatever you use.

Click to expand...

Methonol will work too, but its more agressive than isopropyl and is fairly toxic to the touch, and to inhale, so I avoid using it unless I need it. (that and methonol is hydroscopic so it degrades over time and Acetone does not) Usually labs use pure Acetone to clean glass hard coated optics. if something is really stubborn, then they'll do about a 60-40 Acetone-methonol mix. I just use pure Acetone. Don't use unfiltered stuff from the hardware store though. it has a habit of having contaminates that will scratch your optics. certain optics can only be cleaned certain ways. but the outside of HeNe mirrors are not picky, they're pretty tough.

as for the outside of the glass bell, the same will do if you want it pristine, or a little water or alcohol will do as well, just be careful not to break it. you're essentially holding a thin, fragile glass bottle so don't be too rough with it or drop it. they can be a bit slippery...and of course, make sure its completely dry before running it again.

Kaiser, this is where we agree to disagree:

The rule I've used for the past 20 years is Acetone is for Grease, Methanol for everything else. And Methanol for intra-cavity use. While Methanol is more agressive, it usually leaves less residue, vaporizes better, and has less interaction with residual UV from the plasma then Acetone. SP, Coherent, and the top three makers of industrial YAGS agree with me in their manuals.

My Employer (5th largest scientific laser producer) bans Acetone from use unless a fingerprint is the culprit. Acetone attacks the edges of certain kinds of coatings over time, especially ultrafast coatings.

Europe pushes Methanol as toxic, where in the States its more accepted.

So we used Ethanol when on training missions in Europe.

For home use (IN USA) on a HENE I'd use 90 per cent Isopropyl from a drug store. While there get some Puritan brand throat swabs with wood sticks. Usually the pharmacist has them in better drug stores, and no prescription is required, but you will have to explain why you ask for them. The sterile wood ones use no glue to hold the cotton on, unlike ordinary household Q-Tips. The solvent dissolves the glue, and you end with more residual Crud on your optics. The wood has been gas sterilized, and this removest the easily dissolved organics. If your quick, and if you flush the swab once, there is no residue from the wood. A single package of Lens Tissue from Thorlabs is cheap if sent postal. The better the swab or lens tissue, the less the likelyhood of scratches.

Steve