Astigmatism aberration as a function of distance

Posted by Lu Yan on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Astigmatism-aberration-as-a-function-of-distance-tp7582827.html

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Hi folks,

I am building a fiber based confocal microscopy setup (with sample stage
scanning). But I always got some astigmatism aberration in PSF measuremnts.
The similar aberration was there even I replaced the objective lens with a
regular lens and imaged my illumination beam through that lens with a
camera. I got elongated beam 'spot' on both sides of the focal plane, and
the orientation of the two 'spot' were orthogonal. I think that is
astigmatism aberration if I am not mistaken. I draw a schematic in Evernote
so I can include it here. Here is the link:
https://www.evernote.com/shard/s275/sh/55130807-98d4-4748-a4a9-64d19650b695/be0756284a13da18fe6d1f7f419cbcfe
(copy and paste if the link does not work in email)

I tried to adjust both lens in xy to avoid off-axis incident, but the
aberration would go away. So I got confused where they came from. I hope
someone here could lead me a direction to further look into it.

Thanks very much,
Lu
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Lu Yan
Nanostructured Fibers and Nonlinear Optics Laboratory
Electrical and Computer Engineering
Boston University
8 St. Mary St., Boston, MA, 02215
[phone]
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