Posted by
Kyle Michael Douglass on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Astigmatism-aberration-as-a-function-of-distance-tp7582827p7582834.html
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Hi Lu and others,
On 11/05/2014 10:08 AM, Yan, Lu wrote:
> 1) my beam splitter is those cube beam splitter. I should have mentioned
> that even without beam splitter, when I imaged the collimated beam through
> a lens far away from the collimation lens [between two lenses are just two
> mirrors (1 inch Thorlabs silver protected mirror)], I got similar amount of
> astigmatism. [To Mark: would mirrors usually also cause astigmatism in
> microscopy? Then does that make sense to use larger mirrors? my beam 1/e^2
> size is about 5 mm in diameter.]
>
OK, if it's a cube then you probably don't have any warping of the
reflecting surface. And mirrors tend to be flatter than dichroics, so I
doubt they're warped (unless you've mounted them in a way to put a lot
of stress in one direction of the mirror).
Like Mike suggested earlier, I'm now thinking that it's likely a problem
with the collimator. Since it's an air-spaced achromat, I suppose it's
possible that the lens are misaligned relative to one another.
What happens if you try a singlet lens with the same focal length?
Kyle