Re: Fibre optics.

From: Howard Shapiro (hms@shapirolab.com)
Date: Mon Mar 01 1999 - 17:56:51 EST


Rob Wadley writes:

>	I manage a lab with 3 laser based cell analysis instruments.  They include
>a MoFlo high speed cell sorting cytometer,  a Compucyte Laser Scanning
>Cytometer & a Bio-Rad Confocal Microscope.  The confocal runs an optical
>fibre to deliver its laser light from the laser to the instrument.  This
>seems to becoming more popular with confocal microscope systems.  I can see
>advantages in this type of system for my lab.  In a big lab with several
>machines within a reasonable radius you could have a battery of different
>lasers & use the optical fibre setup to mix & match across different
>machines depending on the requirements at the time.  Any thoughts?  
>	One of the disadvantages is that confocals & scanning cytometers (both use
>microscopes & slides) tend to use very low MW output lasers (~15 MW), where
>flow cytometers use much higher output lasers (100 - 300 MW).
>	I understand that another problem is the loss of coherence due to the way
>light is transmitted along an optical fibre, & a loss of power, as little
>as 10% of the output of the laser reaches the end of the fibre(?).
>	If the problems could be resolved, it could save on duplicating lasers on
>each piece of equipment, & mean there was more money for a wider variety of
>lasers to cover a wider range of applications.  
>

Thus far, it has been difficult to get a substantial fraction of the output
of a laser into a fiber while preserving mode structure and polarization;
this is why we don't have 488 nm taps on the wall of labs along with power
plugs, water, air, gas, and vacuum.  Things may change but it's hard to say
when.  It is more likely in the short run that the large lasers will be
replaced by smaller (although not less powerful), more efficient, less
expensive (solid state or diode) ones, at least for many wavelengths of
interest.

On the other hand, if you have a lot of instruments on a largish (4 by 8
foot or so) optical table, it is entirely feasible to put a beamsplitter or
two in the path of a large ion laser beam and run two or more cytometers (or
other instruments) from the beam; this was done on a Cytomutt I called
Cerberus in the late 1970's.

-Howard



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