Hello,
somebody asked me about the magnification of our TIRF microscpe, however
this should also apply to confocal systems. I came up with the following:
The optical resolution of a high NA system is about 0.2 micrometer and
applying 2x Nyquist sampling this is about 100 nm for one pixel (on CCD or
confocal). At the end of the image processing pipeline this will be printed
or displayed somewhere at a resolution visible to the eye. This should be
one line pair per 1/60th degree which is about 70 micrometer at 25 cm
viewing distance. Gong from line pairs to pixels would give 35 micrometer
and the magnification would then be 35/0.1 = 350 x (rather low). Of course
one could print it bigger and on a compter screen it would be much bigger
but this would be empty magnification. Is this right? Why is useful
magnification for optical microscopes given as 500 x NA which would be 700x
in the above case? Is this because the fluorescence is so dimm that the eye
achieves lower resolution?