Refinish a Yag rod?

[Hemlock_Mike]

Who polishes and recoats NdYag rods? I have one which
needs a job on one end. It got a little crap burned onto it.
As I recall, it has ~ 2 Deg angle on it. Try to keep it low $.
HMike

The big rod is ~ 6" x 3/16" -- I have another 5 mm x 90 mm
with a small pit at one end but at the very edge.

 

[Hemlock_Mike]

BUMP -- Someone still makes NdYag rods.
They must know how to refinish an end.
HMike

 

[ultimatekaiser]

I don't think it can be done non-commercially. :/ I've never heard of an in-home solution to this. once the optical surface is destroyed its permanent unless you regrind it smooth again, which would alter the length of the rod and then it would have to be re-coated as well...are you sure it can be done mike?

Edit: maybe try getting a quote from http://www.cascadelaser.com/opre1.html

 

[Hemlock_Mike]

The pits are tiny burn marks.
It will need to be polished off and a new AR coating
applied. This rod has about 2 Deg face angles.
I believe they were called Bruester angles.
Thanks -- HMike

 

[ultimatekaiser]

That would make sense but I reiterate that if it doesn't come off with a chemical rinse the ultrasonic cleaning is the next best step. After that it needs a resurface. The optical surfaces are very fragile. Can you get a good picture? I've done some yag cleaning, but generally it's a no go. You can't handle them bare handed, and the surfaces degrade on contact with literally anything. Touching them short of a resurface will damage them permanently

 

[Hemlock_Mike]

Ulti.... -
I built this laser ~25 years ago. I mounted the rod in
black O-rings which splattered all over from the heat
of the flash tubes. It is possible the spots can be
removed with Freon solvent.
I have been afraid to fire it again because the damage
would get worse.
HMike

 

[ultimatekaiser]

Ah! Ok well that I didn't know. You hadn't told us that, I was under the impression there was actual damage to the rod itself. What is it coated for? Most yag rods I wash with lab acetone. It can dissolve rubber slowly. Perhaps that would work? I know hydrocarbons do as well but the impurities probably would be bad for the rod/coatings?

 

[Hemlock_Mike]

I'll try the acetone wash first.
I hate to take it apart and loose
alignment. HMike

 

[ultimatekaiser]

I know what you mean. I rinse a glass beaker with distiller water and then fill it with lab grade acetone and let suspend the end of the rod in the acetone and let sit for a while, possibly with the occasional swirl for stubborn debris. This lets gravity pull the gunk off without touching the end to anything. If you see progress I'd change out the acetone after a bit to make sure nothing suspended in it is in for a revisit. The rod is pretty tough, but the coatings are very easy to damage.

 

[Hemlock_Mike]

There's a couple little spots where the O ring
splattered from the flash tube heat. Thanks for
the acetone suggestion.
HMike

 

[ultimatekaiser]

no worries, thats how I clean most non acrylic optics with softer coatings, since they scratch easy. it tends to do the trick best, short of ultrasonics. sometims adding a little methanol to the mix helps dissolve a few things that the acetone won't, and then it can bet rinsed in pure acetone to prevent streaks. just depends on what it's made of and how much effort you want to put into cleaning it. I dont have a PSS YAG, but I've cleaned and re-aligned my friend's a few times. let me know how it turns out and good luck!