RE: 50 mW violet laser

Hi Dave...

 

Violet lasers diodes in the 50 mW range have been around for a couple of
years now - they should be at least as reliable as the earlier units.
Several manufacturers have ~100 mW units too.

 

In our experience, having additional power in the violet is a good
thing.	A 25 mW unit will work fine for most immunophenotyping
applications and viability (i.e. Cascade Blue, Pacific Blue, Live Dead
Violet, etc.).	For bright labeling, you may not see much practical
difference between 25 and 50 mW.  However, having more power should
allow better discrimination of weaker surface labeling from background.
Having more power definitely benefits fluorescent protein detection like
eCFP, Cerulean, etc., especially if you are using these probes as FRET
donors.  We see a noticeable difference in eCFP s/n ratio as we move up
in power.  I think this is why the cytometer manufacturers have made the
more powerful unit a standard item.  I think the cost difference between
25 and 50 mW units is pretty small now, too.

 

Enjoy,

 

Bill

 

 

 

________________________________

From: Dunaway, Dave [mailto:Dave.Dunaway@nationwidechildrens.org] 
Sent: Wednesday, April 16, 2008 10:07 AM
To: cyto-inbox
Subject: 50 mW violet laser

 

Flowmeisters, 

	In an effort to create redundancy across a couple of our LSR
II's we are looking at the addition of a 405 violet laser to one that
lacks such.  One of the machines that does have a violet laser has a
Coherent 25 mW.  In a quote the we received from BD they specified a 50
mW laser.  When asked about the fact that we wanted the 25 mW version
the response we received was that they weren't sure if they still
offered a 25 mW version.  That aside, this situation has raised a couple
of questions that I am hoping someone on the listserve could address.

	Our rationale for wanting the 25 mW rather than the 50 is that
higher power of the 50 will create a greater difference in signals
generated, thereby moving away from our goal of redundancy across
machines.  While no two machines will ever be exactly the same, and
proper controls and data analysis would be paramount we want to be
prepared to allow our users to switch between machines in the hopefully
rare case of there being no other choice.  In your opinion does the use
of a 50 vs a 25 create more potential disparity than both machines
having 25's?

	Secondly, does anyone out there have experience with the 50 mW
laser?	Is it more problem prone?  I guess the general question would be
what are the pluses and minuses both in terms of performance and
reliability with regard to the stronger laser?	Thanks in advance for
your input.

Dave 







David Dunaway 
Flow Cytometry Core Laboratory 
The Research Institute at Nationwide Children's Hospital 
700 Children's Drive 
Columbus, Ohio 43205 
(phone) 614-355-2820 
Dave.Dunaway@nationwidechildrens.org 

________________________________

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