We theoretically derive the electric field distribution of an astigmatic Gaussian laser beam after it is focused through a high-aperture objective. We show that astigmatism values that are hard to detect in the collimated laser beam can have a large effect after diffraction-limited focusing. Such astigmatic beams may be frequently encountered in fluorescence correlation measurements and in laser-scanning confocal microscopy. We present experimental measurements of the excitation intensity distribution measured by 3D scanning of single fluorescent molecules immobilized on a glass surface.
© 2005 Optical Society of America
Diffraction and Gratings
Ingo Gregor and Jörg Enderlein, "Focusing astigmatic Gaussian beams through optical systems with a high numerical aperture," Opt. Lett. 30, 2527-2529 (2005)