polarized vs unpolarized lasers

Posted by Aryeh Weiss on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Re-Recommendations-for-commercial-multi-photon-system-purchase-tp3499069p3621181.html

Our Nikon rep has recommended to a C1 user to replace a failing 543nm
HeNe laser with an unpolarized 2mW laser. This C1 has no AOTF, and
combines three beams into a fiber which feeds the scanhead.

I was under the impression that using an unpolarized laser is a bad idea
because I recall that in an unpolarized HeNe, two orthogonal
polarization modes lase together, but they drift across the bandwidth of
the cavity as the laser warms up. This results in a slowly varying
change in the relative polariation of the beam over time. In a system
where reflections from dielectric surfaces can be dependent on
polarization, this should be a problem. If the fiber is polarization
preserving, it should be a big problem.

So -- does anyone out there know if my understanding is correct? Is
anyone using unpolarized HeNe lasers with no problem? I assume that
Nikon would not be offering that laser if there was such a problem
inherent to it, but still...

--aryeh
--
Aryeh Weiss
School of Engineering
Bar Ilan University
Ramat Gan 52900 Israel

Ph:  972-3-5317638
FAX: [phone]