On Feb 13,  5:00pm, Guy Cox wrote:
> Subject: Re: Enhanced PMTs
>
> Actually the true moral of this tale is that if your sample is in water
> you are NOT using an NA 1.4 lens!!!! The NA you are actually using will
> be ~1.22 but the image will be so seriously distorted by spherical
> aberration that this figure doesn't mean much.  In this case opening
> up the pinhole won't make matters that much worse ......
>
> If you really want to image samples in water you need a water immersion
> lens!
>
The beads I was looking at were sitting on the glass, and since they are so
small I dont tihink I was imaging through much water (I have an inverted scope,
so the beads were on the cover slip). I have also images very large beads
(about 2-5 micron diameter) and found that they come out nice and round. So I
am not convinced that the images are "seriously distorted" over that scale.
However, if I can disperse the beads in immersion oil, I will redo the
measurement and see how it differs.

--aryeh

--
Aryeh Weiss                          | email: [log in to unmask]
Department of Electronics            | URL:   http://optics.jct.ac.il/~aryeh
Jerusalem College of Technology      | phone: 972-2-6751146
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