*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
*****

Hi All,

I’m sure there is going to be a simple answer here, but it alludes me.

I know the psf is a function of NA and wavelength.

Obviously, with 1P we use a pinhole to exclude out of focus light, and when set at “1 Airy,” you have maximized the pinhole for the particular wavelength you are using.  With 2P, no pinhole is necessary because of the non-linear excitation mechanism.

A user just approached me and asked if/why there would be more out of focus light in a 2P image then in a 1P image with a properly set pinhole.  In a collaborators experiments, there seems to be more background in the 2P image (all other things equal).

Only thing I can think of is a poor beam profile on the 2P.  Maybe a large pulse width would excite a larger spot?

Thankful for the insight.


Best,

Gary



Gary Laevsky, Ph.D.
Confocal Imaging Facility Manager
Dept. of Molecular Biology
Washington Rd.
Princeton University 
Princeton, New Jersey, 08544-1014
(O) 609 258 5432
(C) 508 507 1310