What to take for the Z-sampling, the nominal or foreshortened distance?
The Z-sampling is modfied by foreshortening due to differences in refractive index of the media and the immersion oil: the 'reverse fishtank' effect.
In most cases the z-sampling as specified in the raw datafile is the nominal sampling distance, i.e. the distance the table or objective actually moved in Z without taking foreshortening due to refractive index mismatch into account. The mismatch induces spherical abberation and can have a profound effect on the PSF shape and effective aperture. The PSF generator takes all this into account.
After deconvolution the remaining geometric distortion can be corrected by multiplying the z-sampling distance by the ratio of the medium and immersion refractive index, a number in most of the cases < 1.
See also Fishtank Effect
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Keywords: PSF z-correction<br>
Categories: Faq Deconvolution, Faq Microscopy, Huygens Faq, Imported Faqs<br>
Platforms: Irix Linux Windows Mac<br>
Related products: Hu Ess Hu Pro<br>
