>> We have a BioRad MRC1000 using the LaserSharp 2.1T software in a
> multi-user facility.  We replaced the laser in 5/97, again in 10/97,
> and I had to place a call for yet another replacement today.  This
> is very frustrating (not to mention costly).  Are other labs
> experiencing the same laser failure?  What are you doing to extend
> the life of your laser or far-red line?

Dear Mark

A lot has been written about laser failures in the  past - and I
think your request for advice and guidance on gaining the maximum
life from the laser should be aimed at the confocal manufacturers.
Please would they respond if they're quietly reading this !

Although you didn't say which laser you had, I guess it was a mixed
gas ArKr laser. These lasers generally come with a standard 1000hr / 12 month
warrantee. I was assured by at least 3 of the big confocal manufacturers that
3000hrs and at least 3 years was very common, so I counted on having to
relace/refurbish after that. Hah !

The first ArKr died (red line only) on me within about 11 months
(around 400hrs as I recall), and the next (its replacement) after about
100 hrs ! Both were from Omnichrome via Zeiss around 95/96.  I had to beg
for a laser owners manual, which some very kind technician from the O
company finally mailed me.  I still have no idea why these lasers failed as I
received no feedback from the confocal factory, but the third laser (son of the
replacement) is still working fine. In my experience, you need to get as many
hours on the clock in the first year, because many (?) do fail in that time.

Part of the problem is that the ArKr's from say Omnichrome, are specified by
the confocal company, so Omnichrome (and probably it applies to the others)
simply refers you to Leica or Zeiss, who in turn glibly state they never have problems.
A second issue for me anyway was that the Omnichrome laser first had
to go back to the factory in Germany for diagnosis, and all
naturally the relacements had to be factory checked  -  resulting in
a 6 week downtime (first instance) and 4 weeks in the second. I
suppose things work a little faster in the US and Europe than in
darkest Africa where I was....

My basic advice would be
1. ensure proper cooling for the laser during operation and for at least
    10 min after turning off

2. use at as low a power as possible in general - the life span is inversely
    proportional to the tube current.

3. Use at higher power only when you need the red line.

4. Buy a power meter and use it to calibrate your system and monitor
the output on a regular basis. I found with the "son of the
replacement laser" that  setting the Zeiss software (LSM410) control to 40%
was sufficient to get a good red line. I then programmed the power
setting macro to never run ove 50% so the users couldn't "burn the
laser up". If you're trying to do any quantative work, the laser stability
can be a real problem, particularly since they are "self adjusting"
to some extent (current autmatically adjust to give same wattage read on a
photodiode).  [P.S.  I have just placed an order for a pocket-sized power meter,
(LaserCheck from Coherent) for the new facility I am in:  - it seems to be the most
economical meter the market - hope it does the job OK].

5. Seriously consider an extended warrantee. I would go for a laser
warrantee at least, if I could.

PLEASE would the confocal/laser manufacturers comment, and edit the list above
as necessary. I am sure there are many of us confocalists who feel uneasy
and intimidated by the lasers, just waiting for them to expire at any
moment with no real idea about how and why they are performing (or
not).

Thanks

Ian.

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Dr Ian S. Harper
Confocal Microscopy Facility
Department of Biological Sciences
Monash University, Clayton, Vic 3168, Australia
Email: [log in to unmask]
Tel: +61 3 9905 5635;  Fax: +61 3 9905 5613
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