http://confocal-microscopy-list.275.s1.nabble.com/Deconvolution-of-3D-SIM-data-tp6251420p6273537.html
Great discussion. To answer Martin's question as to what ultimately limits resolution in fluorescence I would say: The specimen! How many of us have specimens with structural preservation at the level of 20 nm, or even 50 nm? Do we know what that preservation really is at 20 nm -- what it "should" look like? All these valuable discussions considering resolution are assuming an a priori knowledge of the specimen we don't have when it comes to biology. This is a good thing. Once we know what the new systems can do they can be applied to our unknowns -- like the cells we've been examining by fluorescence for so many years at 200 nm resolution. Should be fun!
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> On 4/13/2011 5:28 PM, Guy Cox wrote:
>
>> Abbe considered rays diffracted by two points on the sample. The points
>> will be resolved if their diffracted rays can enter the objective. This
>> can only apply to a specimen illuminated from an external source. In
>> fluorescence each point emits light and this is totally incoherent with
>> respect to light from another point. There is no diffraction at the
>> sample so Abbe's calculation cannot be applied. Rayleigh's criterion,
>> based on how the optics turn the image of a point into a disk (the Airy
>> disk) does apply.
>
> This is (for me!) a very intuitive explanation, but it suggests that
> with fluorescence, arbitrarily small resolution can be attained given
> sufficiently high s/n. That sounds something like what you said in your
> earlier posting, except for the phrase "arbitrarily small".
>
> Is that correct? If not, what is the absolute limit of resolution in
> fluorescence?
>
> Martin
>
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