Search the CONFOCAL archive at
http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal

The first item in a google search was the following:

http://www.geocities.com/bioelectrochemistry/nyquist.htm
The sampling theorem states that for a limited bandwidth (band-limited)
signal with maximum frequency fmax, the equally spaced sampling frequency
fs must be greater than twice of the maximum frequency fmax, i.e.,

fs > 2fmax
in order to have the signal be uniquely reconstructed without aliasing.
The frequency 2fmax is called the Nyquist sampling rate. Half of this
value, fmax, is sometimes called the Nyquist frequency. The sampling
theorem is considered to have been articulated by Nyquist in 1928 and
mathematically proven by Shannon in 1949. Some books use the term "Nyquist
Sampling Theorem", and others use "Shannon Sampling Theorem". They are in
fact the same sampling theorem.


also:
http://www.digital-recordings.com/publ/pubneq.html#theorem

Practically?  I bet for an N.A. 1.4 objective the answers will range from
0.08 to 0.2 um with the most votes around 0.15 um.  I aim our users to
0.15 um, but oversampling does have its uses.

-Michael