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Sme comments:

David Knecht wrote:


> Is the excitation spot size for a laser scanning confocal microscope
> the same as that of an epifluorescence widefield microscope (same
> objective, etc.)?

By this I take it you really mean "is the excitation spot size of
a confocal microscope equivalent to the resolution of a widefield
microscope".  The answer is yes - a scanning non-confocal fluorescence
microscope will give an image which is completely equivalent to that
from a widefield microscope.  There is in fact a theorem to this effect.


  Put another way, if I removed the PMT pinhole,
> would I get an image comparable to a widefield image?  Thanks- Dave

This, however, is not quite the same thing.  No regular confocal will
allow the pinhole to be opened up sufficiently to be equivalent to
a widefield detector.  Systems with fibre-optic detection will have a
'pinhole' of sorts provided by the fibre - even if you actually removed
the pinhole the PMT has a finite size, and so on.  The image will
always be partly confocal.

The only way you could get a truly non-confocal image would be to use
transmitted or non-descanned detectors as used on multiphoton
microscopes (obviously with a regular dichroic rather than a reverse
one).

On a Nipkow disk system you can get a non-confocal image be removing
the disk but of course this isn't a scanned image.

I'm intrigued as to why you want to do this .....

                                                        Guy