We see they same thing in dye labeled lipid vesicles.  It has to
do with the dipole orientation with respect to the laser polarization.
Taking 2 images using a quarter wave plate with one should show you
equal presence.  You may also see this effect if you use the beam
rotator on the SP5 


Joe Goodhouse
Confocal Core Lab Manager
Dept. of Molecular Biology
Princeton University
609-258-5432

Visit us at http://www.molbio1.princeton.edu/facility/confocal/   


-----Original Message-----
From: Confocal Microscopy List [mailto:[log in to unmask]]
On Behalf Of Koo, Lily (NIH/NIAID) [F]
Sent: Thursday, October 02, 2008 4:40 PM
To: [log in to unmask]
Subject: cell membrane image

Dear all,

When we imaging erythrocytes labeled with a membrane dye on a SP5
confocal, we noticed that in all images, the top and bottom of the cell
membrane appeared much dimmer than the left and right sides of it.  Is
there a particular reason for this observation?  Is there a difference
in the resolution of the x-scan vs. y-scan?

Thanks much.

Lily