Not filling the rear aperture produces a larger spot size. Simply, you
are effectively reducing the NA of the lens.

Mark Cannell

David Knecht wrote:

> Sorry for the dual posting.  I forgot to change the subject.
>
> Dear users- What is the effect of not filling the back focal aperture
> of an objective in a point scanning confocal system.  I am assuming
> the same laser power going in, but the beam not expanded as far.  It
> seems to me that it is a different issue than in a normal imaging
> system. Would you get a smaller spot of illumination?  Thanks- Dave
> --
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