Re: 633 nm laser replacement

Posted by Stanislav Vitha-2 on
URL: http://confocal-microscopy-list.275.s1.nabble.com/recommended-distortion-target-for-multiphoton-tp7582387p7582408.html

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I would also watch for polarization direction. I recently replaced a ~3 mW
543 nm laser on our confocal with a model with the same dimensions and
specs but from a different manufacturer. Both the old and the new tube
have random polarization (i.e., the polarization direction fluctuates), but in
the new tube the polarization direction seems to fluctuate more. I suspect
that since there are several mirrors in the laser and signal path and the
polarization plane has effect on reflectivity, the resulting signal detected on
the transmitted detector (or on the confocal detector when working in
reflected mode, using a mirror slide) seem  to  fluctuate slightly, resulting
in a subtle stripe pattern in a uniform sample.  No problems in fluorescence
mode, though.
I think a quarter wave plate in front of the laser exit aperture would fix this
problem.

Stan Vitha
Microscopy and Imaging Center
Texas A&M University