Re: Laser recharging/replacement ?

From: Megsinet (
Date: Tue Apr 20 1999 - 08:35:56 EEST

----- Original Message -----
From: Ross Gates <>
To: Simon Slater <>
Cc: <>
Sent: Monday, April 19, 1999 7:38 AM
Subject: Re: Laser recharging/replacement ?

> We are just having one of our 250 Omnichrome lasers rebuilt now. We
> retube them as 40 mW. The cost is $9,300. Also, we send in the power
> supply for a check over and for matching to the laser. The cost for
> this is $250. Even though we buy a 40 mW retube, we have never seen one
> come in as such. Usually, it is around 35 mW at the head. The power
> typically drops a few mW in the first hundred hours or so and then
> stabilizes. For maximum laser laser life, we will remelt every 1,000
> hours.
> Omnichrome was bought out by Melles Griot. Since then their retubing
> time has increased dramatically. Years ago we could have a laser turned
> in less than a week, then it took several weeks. They are now quoting us
> 5 weeks. Since we have two SLA250 and a SLA500, it doesn't hurt us to
> have a machine down for this long, but if you had only one machine and
> no laser core to rebuild, it would be worth it to pay 3D Systems top
> dollar to get one right away.
> Melles Griot just purchased Liconix, so now the Liconix laser people are
> in the same boat as rest of us.
> Ross Gates
> Select Mfg. Services
> Muskegon, MI
> << Even though we buy a 40 mW retube, we have never seen one
 come in as such. Usually, it is around 35 mW at the head. >>
Is that their policy? Any decent laser I ever heard of is delivered at
than rated power. If their guerrantee is for 60% of rated power then they
half way to replacement on delivery. Why don't they call it a 35 mw laser
Andy Scott
Lockheed Martin Aerospace


 Agreeing with Andy Scott, it seems unusual that your 40mw lasers are coming
in under spec. Grounds for massive complaint I would think. I have swapped
out and tuned over 125 Liconix 40 mw HeCd lasers and have never run one that
was under spec. Usually 5-10 mw over spec. power. During shipping you can
lose as much as 10 mw because the bore shifts around inside the head.
However, you or your 3D Systems FE should be able to tune it back up with
the A-B-C 7/16 bore sockets for Omnichrome models or if you have the Liconix
big-frame models, 5/16 sockets on the inside of the covers and their small
frame units have Allen-wrench sockets on the outside/end of the cover. I'm
starting to sound like a technical manual... Other than that, if you are not
checking the true power at the head, you could be losing some serious power
from dirty or burnt-out optics and mirrors on the way down to the vat where
your power sensors will give you a low value.
 Now, I mentioned my experience with Liconix lasers but we recently
purchased a 50 mw laser from Omnichrome (Melles Griot), we were able to get
64 mw at the head. So to me at least, the above spec standard seems to hold
true in my book.
 The 5 week turn-around Melles Griot is quoting for re-tubing lasers, as you
mentioned, concerned me a great deal. I talked to our Milles Griot rep and
he assured me that they will shortly have in place a swap plan, similar to
what Liconix had. i.e.: your laser dies, you have one shipped out to you the
next day, you swap the dead one in the box for the new one, send it back and
get billed later. Anyway, this is what I was told will happen for the new 50
mw laser we just bought, I don't know about their 40 mw models.

 One last ditty...I've yet to re-melt a laser because the Liconix design
positioned the Cadmium in the bore so it would never get in the way of the
reflecting photons, thus eliminating re-melts, but since we just bought this
Omnichrome model, I consulted a friend with about 6 years experience with
Omnichrome lasers. He told me this, "Between 500-700 hours you will see a
drop of about 10 mw, do 3 re-melts in one day, space them out 2 hours each.
After that, re-melt once every 800 hours or after 7-8mw drops". Like I said,
I never re-melted a laser before but I will follow his instructions and see
what happens...and hope he isn't screwing around with me :)

Sorry to ramble on, but it is a subject that I'm familiar with, just
thought I would share. If you have any questions, feel free to call.

Bill Ballmaier V.P.
Scimitar Prototyping Inc.
1529 Bourbon Parkway
Streamwood, IL 60107

Phone: 630-483-3875
Fax: 630-483-3876
EMail: (active 5/3/99)

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