Simulating the focal volume effect: a quantitative analysis

We present quantitative simulations of the focal volume effect. Intensity distributions in detection volumes with two- and three-dimensional spatial resolution are calculated. Results include an analysis of translations of these volumes in the focus along the direction of laser propagation as well as discussion of varying sizes of the spatially resolved volumes. We find that detection volumes less than half the 1/e full-width beam waist and less than half the Rayleigh length along the propagation direction offer an optimal compromise of maintaining intensity resolution without sacrificing peak intensity.