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Hi John,

I do not know the answer to your first questions, but I can give you an answer to your third question.
Spinning disk systems that I am familiar with have a fixed pinhole size that is optimized for a particular objective, usually the highest power objective.  Therefore, the lower power objectives have a larger optical section.  With a small enough power objective, for example, the optical section becomes very large and might even be considered to be non-confocal.  For example, if a 100x objective has a 0.91 micrometer optical section then on the same system a 5x objective has a 95 micrometer optical section.

Lon

Microscope manager
Department of Biological Sciences
University of North Texas


Sent from my iPad

> On Jan 28, 2014, at 11:04 AM, "John Oreopoulos" <[log in to unmask]> wrote:
> 
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> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> *****
> 
> I'm wondering if the listserver can help me recall something I've heard several times before and point me to a reference that proves (and demonstrates) it. Several people I think have said before (I'm looking in the direction of Jim Pawley and Guy Cox perhaps) that beyond a certain confocal pinhole size (in terms of Airy units), the image that is produced by the confocal microscope is equivalent to that which would be obtained with a regular widefield epifluorescence microscope without confocal optics.
> 
> 1. Can someone tell me at what confocal pinhole size this happens?
> 2. Can you also tell me where this was shown in the confocal literature for the first time (or a equivalently in a review article on same the topic)?
> 3. Does this principle also apply to spinning disk confocal microscopes, why or why not?
> 
> Thank you greatly for your wisdom.
> 
> 
> John Oreopoulos
> Staff Scientist
> Spectral Applied Research Inc.
> A Division of Andor Technology
> Richmond Hill, Ontario
> Canada
> www.spectral.ca