Posted by
David Baddeley on
URL: http://confocal-microscopy-list.275.s1.nabble.com/which-multiline-gas-laser-should-I-buy-tp6401184p6401496.html
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I can't remember the exact model of Ar/Kr - it was the stock laser in a Leica
TCS NT and was air cooled. It was probably being used ~15-20 hrs/week so a bit
over 1000 hrs would be about right. We also had a couple of pure Ar and a pure
Kr large/medium frame lasers (Spectra Physics, Lexel), and these fared a lot
better although they still gave us a few headaches with tube replacements.
As to tips on prolonging tube life, the commonly accepted ones are:
- don't run at full power - I have heard that ~20% and below is pretty good for
longevity
- don't switch on and off more than you have to (ie leaving the laser running at
low power all day is better than turning it on for an hour or two 2-3 times a
day). Exactly where the turn on /runtime balance lies is the subject of much
debate.
- let laser cool properly before switching on again
- make sure you're cooling water setup is absolutely bombproof. Important things
to watch here are:
- interruptions/ pressure variations (we think we lost a tube to a
water-hammer type effect)
- calcification - if you've got hard water, you'll get a build up of
calcification in the tube - this stops it being cooled effectively, and, if the
calcification starts to flake, allows water to be trapped next to the tube and
boil (we definitely lost one tube this way). If you're stuck with hard water,
you can do a bit of preventative maintenance by rinsing the laser with a dilute
solution of a weak acid (eg. acetic) every 6 months to a year. This is however a
half solution at best as there are also metal parts in the cooling loop that you
don't want to corrode.
- leaks - the required flow rates are such that any leak in the cooling
circuit will quickly flood your lab. Combined with 3 phase laser power supplies,
this is not a particularly comforting prospect.
In general solid state lasers are much less hassle, and a lot safer. I'm not
sure what the current prices are, but would guess that either of the lasers you
are looking at would probably set you back somewhere in the vicinity of $50-70k.
You should be able to get solid state lasers at the desired powers for much less
than that ($1-5k each at your powers, if you're a bit flexible with your
wavelengths. If you want to exactly match the Ar/Kr lines, in particular 488 and
514 you will need to fork out a little more). You might not be paying directly
for your power / cooling water, but gas lasers are also horribly inefficient -
the Innova 70 draws up to 25KW -> ~ $12K/year power and cooling costs
(calculated at 1000hrs/year, 20c/kwh[nz prices], cooling power at 1.5x
electrical[optimistic]). Maybe you can use this as a bargaining point to get
your institute to chip in a few extra dollars for a solid state solution.
cheers,
David
----- Original Message ----
From: Yuval Ebenstein <
[hidden email]>
To:
[hidden email]
Sent: Wed, 25 May, 2011 3:58:18 PM
Subject: Re: which multiline gas laser should I buy
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Hi David and Martin,
Thanks for your comment. I'm curios to know which Ar/Kr you were using.
I know at least two Coherent heads that are running on the same tube for several
thousands of hours and for over 10 years.
I totally would prefer solid state but I need 4-5 lines with high power
(150-250mw) and the solid state at these intensities are super expensive.
Overall I will be paying about double for a solid state set and I just can't
afford it.
Would love to hear more and get tips for extending their life...
Yuval
On 5/24/2011 8:21 PM, Martin Wessendorf wrote:
> Deare Yuval--
>
> I second David Baddeley's comments. Kr/Ar's were a great idea at the time
>(1993) but are obsolete for exactly the reason he mentioned: they tend to die
>young. We always figured on 1000 hours out of ours.
>
> Good luck!
>
> Martin
>
> On 5/24/2011 7:28 PM, Yuval Ebenstein wrote:
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>>
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy>> *****
>>
>> Hello,
>> I'm looking for a cheaper alternative for a high power solid-state laser
>> combiner.
>> I'm thinking of buying an Ar/Kr (which gives almost every excitation
>> line I can think of) and I can't decide between the Innova 70c-spectrum
>> from Coherent and the Stabilite 2018-RM from Spectra-physics. They are
>> quite similar on paper but the spectra one is cheaper. I heard much
>> about the robustness of the Coherent model.
>> Anyone has experience with one of these? Anything special I should look
>> for?
>> Many thanks
>> Yuval
>>
>
>
>
-- --------------------------------------
Yuval Ebenstein
Department of Chemistry and Biochemistry, UCLA
Young Hall-2002, 607 Charles E. Young Drive East
Los Angeles, CA 90095-1569
Ph: (310) 794-6685; Fax: (310) 267-4672