[Cytometry] Optical pathways: mirrors or fibre optics?

Perfetto, Steve (NIH/VRC) [E] sperfetto at mail.nih.gov
Sun Feb 15 12:05:23 EST 2009

All of our LSRs and one Aria uses the air launched approach and while on oc=
casion the mirrors require slight adjustment this can be done quickly by th=
e operator. Our other Aria is setup with single mode fiber optics and if th=
is instrument goes out of alignment (frequently enough) a service call is r=
equired. In addition, as Marty stated the 405 (50mW) will break down the fi=
ber optic and has greater power loss, hence requires more monitoring. For t=
hese reasons we prefer the air launched technology.


On 2/14/09 7:02 PM, "Marty Bigos" <bigos at stanford.edu> wrote:

There are two types of fiber optics used in the BD instruments, single-mode=
 to bring the laser light to the flow cell, and multi-mode, which brings th=
e light from the fluorescence collection objective to the PMTs. The multi-m=
ode fibers have low light loss ( < 10% ) and last quite a while; the single=
-mode fibers have wavelength dependent light loss (shorter, the lossier) an=
d become unusable with UV light. For 405 violet solid state lasers the loss=
 is about 30%. However the single mode fiber preserves beam shape, which is=
 important for excitation in a cytometer - the multi-mode doesn't, but that=
 has no affect on the sensitivity of the measurements. The SORP instruments=
 gain sensitivity by using mirrors ("air launched") to direct the laser bea=
ms. However, this can lead to greater problems with alignment drift of the =
input beams than with fibers, and more difficulties in configuring multi-la=
ser systems.

Power transmitted through the fiber is limited by wavelength and heating of=
 the fiber. The fibers BD uses do not have heat problems with the 405 50 mW=
 violet; I would not be surprised if they are OK for the 150mW 532 as well.


             "Helen Ferry"
             <helen.ferry at imm.
             ox.ac.uk>                                                  To
             Sent by:                  <cytometry at lists.purdue.edu>
             cytometry-bounces                                          cc
                                       [Cytometry] Optical pathways:
             02/10/2009 10:11          mirrors or fibre optics?

Hi FLOWers

Is there any reason why fibre optics shouldn't be used with high powered
lasers e.g. 150mW, 532nm or 100mW, 488nm? If not, then why are some BD
SORP instruments fitted with mirrors to direct the laser beam to the
flow cell instead of fibre optics, as in the standard machines?

I have searched the mailing list archive and other literature, but
haven't been able to find an answer. Hopefully somebody out there
will know the answer and care to share.



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Stephen P. Perfetto, MS.,MT. (ASCP)
Director, Core Flow Cytometry Facility
Vaccine Research Center, NIH
Building 40
40 Convent Dr., Room 5507
Bethesda, MD 20892-3015

email: sperfetto at nih.gov
Phone: (301) 594-8659


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