photons vs. photoelectrons?

Posted by John Oreopoulos on
URL: http://confocal-microscopy-list.275.s1.nabble.com/Precisely-driving-several-devices-from-IgorPro-through-National-Instruments-board-possible-tp4907273p4913234.html

The recent release of the Photometrics EMCCD "eVolve" camera which has the ability to output images with pixel values that correspond to photoelectron counts (instead of arbitrary digital count units) has me wondering a bit something. The idea behind this camera, as I understand it, is that having images reported in terms of photoelectrons instead of counts (ie: an absolute scale vs a relative scale) will allow a better comparison of image data between labs around the world, and even for single user comparing images acquired with a particular microscope from day to day. Seems reasonable to me and sounds like a pretty good idea. What I'm confused about is that I've seen some papers in the literature, mainly those that deal with single-molecule studies, that report image data in terms of actual photons detected. Is there a difference, and more importantly, can someone explain to me the advantage of using photon counts vs. photoelectron counts?

(No commercial interest for Photometrics)

John Oreopoulos, BSc,

PhD Candidate

University of Toronto

Institute For Biomaterials and Biomedical Engineering

Centre For Studies in Molecular Imaging