Hey, you're right. Interstingly, though, on our Zeiss C-Apochromat 40X/1.2
W used with a 1.5 coverslip and BioRad FluorGard, we measure minimal
spherical aberation and chromatic error when the collar is set to 0.17. In
fact, for a microsphere just beneath the coverslip, we measure no
appreciable difference in the PSF. That is probably because there is not
much media between the bead and the lens.
________________________________________________________________________________
Paul Goodwin
Image Analysis Lab
FHCRC, Seattle, WA
On Fri, 21 Feb 1997, Johannes Helm wrote:
> In answer to the following letter by Paul Goodwin:
> >
>
> Good morning,
>
> I fear there is a misunderstandment about the general characteristics of water
> immersion lenses made for use with coverslips.
>
> > It is definitely different from phenlyene diamine. It is glycerol based
> > with a r.i. of 1.4 something. If you are using a water immersion lens that
> > is made for use with a coverslip, it assumes that the sample is in
> > glycerol, even if the immersion liquid is water.
>
> I am quoting from http://www.zeiss.de/mi/limi_e/p8/capo_e.html :
>
> "
> ...
> For the design of water objectives, the refractive index 1.33 for
> immersion and mounting is assumed.
> ...
> "
>
> This www-page is describing the C-Apochromat lenses 40X/1.2W Korr and
> 63X/1.2W Korr by Zeiss. One of the reasons why these lenses were made
> is that the image quality dramatically decreases if oil-immersion lenses
> are used on objectives in watery solution. These C-Apochromats, which exist
> in modified forms even as non-coverslip lenses for the application in
> electrophysiology, are made for a substance with the refractive index
> close to water as immersion-medium and mounting-medium. A correction collar
> can be used to correct for slight mismatches in thickness of cover-slip and/or
> mismatches in refractive index, when e.g. using physiological salt solution
> instead of distilled water.
>
> Another type of objectives are the multi-immersion lenses which are designed
> and built to be used with different immersion and/or mounting media and with
> or without cover-slip. Examples of these lenses are presented in, e.g.,
>
> http://www.zeiss.de/mi/limi_e/p8/multi_e.html
>
> and
>
> http://www.zeiss.de/mi/limi_e/p8/l_pn_e.html#multi
>
> .
>
> I suppose that these facts also are valid for Nikon lenses as presented e.g. in
>
> http://www.nikonusa.com/products/biomed/bg/advresearch/e800/accessories/accessories.html#objectives
>
> Best regards,
>
> Paul Johannes Helm
> --
> I do not have any affiliation to a commercial company. All the information provided
> is private information given to the best of my knowledge but without any guarantee
> for correctness.
> --
> *****************************************************************************
> Paul Johannes Helm
>
> Mailadress: Department Physics 4
> The Royal Institute of Technology
> S-100 44 Stockholm
> Sweden
>
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> The Royal Institute of Technology
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>
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