Re: Coherent Sapphire laser and BD FACSVantageDiva

   Adrian  -

   We have a Sapphire 200mW on each of two Vantages.  On one, the 
laser spot is visible;
on the other, the spot is not, and we have the same problem with it 
that you describe.

   While we haven't investigated this in detail, my first guess would 
be that the on the
invisible spot Vantage, the sample core is off center toward the 
fluorescence objective,
and the laser hits the jet more on the side that won't	reflect light 
out toward the viewer,
or, conversely, the visible spot Vantaqe has its sample core 
displaced in the opposite
direction so the viewer sees more light.

   As you say, this makes alignment more difficult, but, as you 
probably have deduced,
the initial placement of the jet in the laser beam can be done with 
the chamber door open
and the beam interlock defeated, while looking at the spread of the 
beam onto the
scatter obscuration bar, and the laser position can be checked in the 
viewer with the
door closed by boosting some calibration beads and viewing the spot 
at the laser-jet
intersection.

       -   Dick


>Hi all,
>
>We've have just had a 200mW Coherent Sapphire installed on our
>VantageDiva to replace on old Coherent I90. So far we are very happy 
>with it apart from one aspect - we can no longer see the beam spot 
>on the stream. This makes alignment somewhat more difficult than 
>previously. I think we are getting used to it but it would be nice 
>to be able to see the spot.
>
>Our Coherent engineer recalled hearing of this as a problem but 
>couldn't remember any details. Our BD engineer had never seen it 
>before.
>
>Has anyone else seen this? Any suggestions for what might be behind 
>it and how we might fix it?
>
>Regards,
>
>Adrian Smith
>Centenary Institute, Sydney, Australia


-- 
Richard Stovel	3-6959
Herzenberg Lab and Stanford Shared FACS Facility
Beckman Center for Molecular and Genetic Medicine    Room B016
email:	stovel@stanford.edu
Phone: 650-723-6959    FAX: 650-725-8564