dual laser optical adjustment

Eric Van Buren aa9080 at wayne.edu
Thu Aug 20 18:31:31 EST 1998


I would guess there is a problem with either the timing or alignment of the
second laser. I would check the dead time first. Are the signals from the
second laser very wide (i.e., long time)? Is the dead time adjusted too
narrow (i.e., short time)? Try lengthening the dead time. Are you using
pulse processing? Next check the dual-laser delay; you should have a 17
microsecond separation between signals from the two lasers (when using a 70
micron nozzle and 10-15 psi sheath pressure). While keeping this delay
fixed (i.e., don't adjust the dual-laser delay knob), optimize the signals
from the second laser. If that doesn't help, make sure the fluorescence
obscuration bar is blocking both lasers. Finally, try the full dual-laser
alignment as described in Appendix A of the FACS Vantage User's Guide. Does
the problem appear when running beads, samples, or both?

>Hi everybody,
>the following technical question: optimized signals from the second
>laser on our FacsVantage (very sharp peaks, strong signals) result
>in sort of a quenching of the first laser signals (significantly
>lower signal intensity, but same CVs). When I block the 2nd laser
>beam, the signals from the 1st laser jump up again. Has
>anyone seen this effect before? Could it be that the two laser beams
>intercept at one point, so the red laser eats up enery from the blue
>one (wild guess)? Thanks for any hints,
>Dr. Marcus Reckermann
>Forschungs- und Technologiezentrum Westküste (FTZ)
>25761 Büsum
>Tel: 04834-604-204 oder -261
>Fax: 04834-604-299
>E-Mail: recker at ftz-west.uni-kiel.de

/\/\/\_ Eric Van Buren, aa9080 at wayne.edu
\ \ \   Karmanos Cancer Institute and Immunology & Microbiology
 \_^_/  Wayne State University, Detroit, Michigan, USA

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