From: FACS_COPY@wehi.edu.au
Date: Tue Nov 11 1997 - 21:56:10 EST
Barry Grimes reports a problem with his Enterprise 621 on a FACSVantage
with TSO:
> I have noticed that when I fire the laser up in the morning the intercept
> is at 47 (arbitrary video unit) and after about 3 hours of warming up the
> intercept has moved down the stream to 53.
The Coherent spec for beam pointing stability on an Enterprise
is < 5 microrad per 30min per degree C after a *15min* warmup. While
I don't know what the "video units" mean, I would guess any pointing
shift *should* be imperceptible on the video monitor.
> Has anyone else seen this intercept movement in these lasers?
We haven't seen shifts of this magnitude. We need to tweak our
Enterprise 621 alignment for maximal signal about twice a day. Your
shift seems to be only vertical; if it were lateral, you would also
loose signal. Can anything other than the laser itself cause you a
vertical shift? e.g. drooping nozzle mounting or video camera
mounting?
> .. Doesn't this
> movement mean problems for proper drop timing?
Potentially yes; if your 6 "video unit" shift is of the order of half
droplets.
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