ALC60x argon laser head rebuild.

Hello!

Decided that I would rebuild my ALC60x head and give it a good clean out in the process. Started today by stripping out the electronics.

Some pics for everyone:

Anode end, there is an extra electrode on each brewster stem. IIRC these were only on older tubes which needed them before ALC came up with improved manufacturing processes... Could be wrong, but the information is on the FAQ.



Cathode end:



Cathode end top view:



Anode end top view:



Bore top view:



Overall view top:



Overall view side:






More pictures to come when I do some more work - probably going to strip the tube out and then rebuild it when I have a PSU to test and realign it with. Also plan on rewiring it with colour coding opposed to black and white wires - if I can get a schematic. Some parts of the casing are oxidised/rusted so I'm going to clean that up, but the tube is in a fairly good condition other than the broken thermostat which snapped in half when I was removing it.

My ALC (different model though) has an electrode just like that on the cathode end. If it's for keeping dust off the brewsters, why don't I have one on the anode end? How exactly does it work? Does a static field attract the particles?

Cyparagon said:

My ALC (different model though) has an electrode just like that on the cathode end. If it's for keeping dust off the brewsters, why don't I have one on the anode end? How exactly does it work? Does a static field attract the particles?

Click to expand...

I'm not sure, theres some info on it on the FAQ in the ALC60 section, it SHOULD hook up to the starter card but mines aren't hooked up to anything, maybe because it's a reprocessed tube?

I will follow this with great interest, I always wanted to re-build an Argon laser.

It would be far more rewarding and educational than just purchasing one that works.

(I'm a sucker for "basket cases" too)

I'd recommend against removing the tube unless you absolutely have to, not only are you going to completely lose alignment on the mirrors, but you are going to get dust on the brewster windows which will lower gain and output power.


Regarding the extra electrodes on the ends of the tube, from Sam's Laser FAQ:

"On some older 60X tubes, you will find a thin wire electrode on each Brewster stem which connects to the interior via a glass-metal seal (but clears the bore) and is wired into the starter card - but have nothing to do with starting.

These are called "catenodes" and are there to aid in keeping residual dust inside off the Brewster windows. They were included before the source of carbon dust in these tubes was eliminated. The catenodes work by neutralizing the charge on any particle before it could hit the window using a soft glow discharge from the wire to the inside of the tube. The plasma greatly accelerates any dust in the tube toward the most neutral place - the Brewster windows, which are the last places you want it! They were no longer required once better processing techniques allowed by hard-sealed windows became available. A few older SP medium and large frame ion lasers also used to have them.

The catenodes do not particularly aid in starting and the tube will run just fine without them. However. the boost voltage on the start card is the only voltage high enough in the PSU to fight the tube and cathode drop. They only need a few hundred microamps to function so the connections are via 88K resistors. All 60X start cards have the pads for the resistors, even after they stopped making tubes with the catenodes. "

Hey Mario, I've not got a PSU for this anyway so it's just going towards aiding my learning about Argon lasers, I can't use it and I can't afford a PSU so I'm just going to learn