🚀 go-pugleaf

I apologize for any tone of exasperation in the following, but we've been
struggling with KrAr lasers for the past 2-1/2 years and have never been
able to offer triple-labelling or any service requiring the red line to our
customers. Well, there have been a few exceptions when we took the
opportunity to use the red line when it was was going well, but obviously
we weren't in a position for people to plan experimental sequences based on
its' availability on any given time or day.

Michael Cammer <cammer@AECOM.YU.EDU> writes:
>These lasers definitely do not have the advertised lifespan.
agreed

...
>Over the years this discussion pops up every once in a while and the
>same answers seem to be posted-- yes, this is a repetitive message.

unfortunately our experience doesn't really tally with this. Our previous
messages (13/5/93 30/8/94 & 23/11/94) asking whether our experience of
lasers lasting only 50-100 hours was unusual didn't get much of a response,
certainly nothing like this thread has generated. There have been some
other discussions regarding KrAr lasers, but for most of the 2-1/2 years
we've been wondering whether we've been doing something wrong. While BioRad
have been supportive in organizing replacements & repair, we wouldn't have
wasted so much angst had we had we been told our experience was not unusual
- we've had a reply from someone who's had fifteen (count em, 15!)
replacement lasers over the past two years. And what's more we would have
asked for a replacement laser much earlier, instead of putting ours through
half a dozen returns to ILT.



Kevin Tice (Omnichrome),, writes:
>Additional information regarding laser lifetime:
>The lifetime of a laser is dermined by many factors; the alignment of
>the resonator mirrors, the amount of tube current driving the plasma,
>contamination to optical surfaces, etc all have an effect on life time.
>
>The mirror alignment is very important because it affects:
>1) the amount of tube current being supplied to the laser -
>   if in light feedback control
>or
>2) the output power of the laser -
>   if it is operating in current control.
>
>In case 1), if the mirrors are out of alignment the only thing the
>laser can due to maintain the desired/set power level is to increase
>the tube current to compensate. This in-turn lowers the lifetime of a laser.
>
>In case 2), if the mirrors are out of alignment the output power of the
>laser will drop and the user will have to increase the tube current
>manually by increasing the power level adjust to achieve the previously
>set power level. Since, there is now a higher tube current level, the
>life time of the laser is shortened.
>
>These are the most likely cases for premature laser failure, i.e. mirror
>alignment.  The other thing to look at would be the laser, to see if the
>product is correct for the application.
>
>The ILT laser produces 4 to 5mW per primary line (488, 568, 647nm) and
>run at a high tube current to get this power - standard physics.
>Therefore it this laser is running at 8 to 9.5Amps most of the time then
>you should only expect to see 500 to 1000 hours of life.  At the same
>token, if the laser is operated at 5 to 6Amps then you should expect 1500
>to 2500, but the power level will most likey to low for use in the
>application.

I'm glad it all seems standard physics, but our feeling is the problem is
either with the ILT design, construction, or most probably both. Certainly
we're very confident of aligning the mirror and while we've had *one* case
of 'contamination', we don't think it explains our recurring problems. One
of the replacement lasers was good for the few months we had it, which
makes us feel the problems are not coming from us or the environment. If
contamination really was the cause of many of these problems you'd think
ILT would have looking carefully for it, particularly from sites with a
consistent series of returns, but apart from that one occasion (and we knew
there wsould be some effects from the the condensation) we get no useful
information accompanying the return of our laser - certainly no indication
that we are somehow fouling the optical surfaces. I lie, the most recent
time the laser returned it came with a sheet listing the power outputs
after 'repair'. We didn't find that loose piece of paper in the packing
case until our green line disappeared after just one week, and were
astounded that ILT returned the laser when they measured the green line to
be half the power it should have been! This time ILT were also supposed to
have change the mirror mounts into gimbal ones, which are not only easier
to adjust but also more stable to the thermal stresses they are subjected
to.

PS wrt to laser current, we'd be quite willing to run at a lower current
EXCEPT that the red line disappears at less than 7.5-9.0 amps. That's one
of the binds we're in, and yes it does seem wasteful to then throw away
most of the generated power with ND filters of 2 or 3. However, running at
an LCV of 2.5V could be useful to people who only occasionally need a red
line and can turn up the power when needed (hoping the red line makes an
appearance). This was the lowest power we checked as still giving
consistent image quality so apart from the absence of the red line it is
not the case that the "power level will most likey too low for use in the
application".

Andy Jacobson <afj@DRMEMORY.NUC.UCLA.EDU> writes:
>We have an Ar/Kr laser that was designed with a special gas mixture
>to give us a more Ar (than Kr) spectrum, specifically, it has 457, 488,
>514, and 568nm, (and no 647 line).
>The laser has been given light-moderate use, and although we haven't tallied up
>all the hours, I would say it is in the 1000 range over the last 2 years.
>One of the things that probably preserves its life is the fact that it
>has a very accessible power control, so we are able to keep the current
>down when not needed, and we train our users to be power misers. The laser
>shows no sign of impending failure. In fact, I'd say it has been about
>the same now as ever. I would not give the thing an absolute glowing
>recommendation though, as we have had alignment problems with heat
>cycling, but it certainly hasn't been like some of the horror stories
>I've heard from some users of this forum. The laser is an LS-1000 from
>American Laser Corp. in Salt Lake City Ut. Cost: ~$11,000
>We use it with a Leica CLSM, on a Fluovert FU microscope.
>Best of luck to all.

It's nice to hear some people being confident about their laser.

Me and Colin both think it's not just a tiny fraction of ILT KrAr lasers
which have problems and the only reason the size of the problem hasn't be
recognized earlier is that many people with KrAr either aren't using the
red line, or don't recognize how poorly theirs is working. Initially we put
it down to the fact the KrAr was known to have a shorter life and be
somewhat more temperamental, but we never thought it would be this bad. Nor
was it clear from people on this list or BioRad how widespread the problem
was. Apart from our original laser which has back for 6 repairs and one
refurbishment, we've used quite a few replacement lasers for periods of
weeks/months, and are very confident of our ability to align a laser well
and to recognize when one is going off. We've aligned a laser in the
presence of a BioRad rep trained by ILT who seemed more than happy. We
learned from him, and he learned about tweaking the mirrors from the
captured signal quality from us.
    The last time ours came back from ILT it included a spec sheet for the
first time. It wasn't until we noticed the green line go off (also for the
first time, and in a few dozen hours) that we compared those ILT values for
the 3 lines against the spec - sure enough ILT had *measured* the green
line was half the power it should have been. Yet they sent it back to us
thinking we'd be happy that they'd tweaked a better red line. All we want
is three stable and working lines and trading one off against another isn't
the way to go. They don't have to be high power, but in the 2+ years of
this facility we've never been able to go to users and say use whichever of
the R G or B lines suits you best because they'll still be working over the
months an experimental sequence can occupy. We haven't been able to do
triple labelling, and we've lost a lot of time while the laser has been
away or limping along. Not being really confident means we haven't
advertised ourselves as much as we'd like to, and consequently the usage
and income hasn't been as high as it should. Just as well we're not in the
good ol US of A or by now we'd be thinking of initiating a class-action
against ILT.

To end on a constructive note, we'd really encourage people with KrAr
lasers to record the laser current & voltage values on a daily basis. This
applies particularly to people for people who receive a new or refurbished
laser, because several times we've seen these drifting off (in spite of
partially successful attempts at retuning) in the first few dozen hours.
Even if ILT think of us as problem customers by now (or more likely with a
dud laser), you think it would be in their interest to run them in for a
while and confirm the laser isn't drifting off badly after 50 or 100 hours.
To be honest, I'm disappointed with BioRad for not encouraging this record
keeping themselves because it's a better way to define the scope of the
problem in a quantitative fashion instead of waiting till the lasers pack
it in. Assuming people even notice the problem. These lasers are a real
problem, not only in terms of KrAr being a finnicky mixture, but with some
people (least not us) being suspicious of the construction quality. It
could really be a useful move for BioRad to not only encourage people
taking daily measurements of the laser (a 30 second job), but to supply a
log book and $30 3-1/2 digit DMM to all KrAr owners. [this was
writtenbefore we heard tghe rumour that BioRad may be shifting to a
different laser supplier]

I'm enclosing figures from our records following the two most recent laser
returns below.

cheers,
Danny Thomas

PS and we don't think running it a low power switch setting will help us
because we've been doing that religously when not scanning, but in spite of
that the red line (and laser power/voltage levels) often start going off
within 50 hours of return! It's very well ventilated, etc, so we don't
think it's anything to do with its' setup either. Also the last repair by
ILT was supposed to include the replacement of the laser mirror gimbals
with higher quality ones that are easier to adjust as well as be more
stable under the varying thermal conditions they're subjected to. Nope, ILT
forgot to do that - they were too busy loosing the green line!

this was a replacment laser (#10121077) while ours was being 'repaired'
date            hours   LCV     ACmv
11-11-94        4       3.1     90-92
15-11-94        7       3.1     91-92
17-11-94        10      3.1     88-97
21-11-94        11      3.1     89-90
25-11-94        14      3.1     92-95
28-11-94        16      3.1     90-92
29-11-94        21      3.1     92-98
30-11-94        26      3.1     96-97
01-12-94        28      3.1     94-101          no red line
01-12-94        29      3.1     94-96           when LCV 2.4
02-12-94        32      3.1     94-95
07-12-94        34      3.1     93-96
08-12-94        37      3.1     92-98
12-12-94        40      3.1     93-96
13-12-94        42      3.1     92-93
14-12-94        44      3.1     93-96
15-12-94        47      3.1     92-95
16-12-94        51      3.1     93-94
19-12-94        54      3.1     93-99
21-12-94        57      3.1     92-95
26-01-95        64      3.1     96-97
07-02-95        68      3.1     98-100
09-02-95        73      3.1     98-100
20-02-95        79      3.1     98-101
07-03-95        87      3.1     98-99
08-03-95        89      3.1     >101           NO RED
09-03-95        91      2.7     93-94
14-03-95        95      2.7     97-101
15-03-95        99      2.7     95-96


ours returns (unfortunately hours not recorded, but this was first 47 hrs)
21-03-95                4.0     81.5
22-03-95                4.0     83-86          poor green line
23-03-95                4.0     85.5-86.5       "
27-03-95                4.0     86-88           "
28-03-95                4.0     89-93           "
31-03-95                4.0     92.5-95        NO GREEN
04-04-95                4.0     94              "
06-04-95                4.0     94-95           "
07-04-95                4.0     94.5            "
10-04-95                4.0     93              "
11-04-95                4.0     91-94           "
08-05-95                4.0     94.5            "
11-05-95                4.0     87-88          GREEN RETURNS!


cheers,
Danny Thomas  (D.Thomas@vthrc.uq.edu.au)

ftp://ftp-boi.external.hp.com/pub/printers/laserjet/doc/4plfaq.txt
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                                         ^^^ truly rooly?