FIGURE 2.

Adjusting the FCS e⁻² radius to account for the effect of finite pixels. (a) The correction factor β, which depends only on the ratio of the e⁻² radius w₀ to the pixel length L, relates w₀ to w_eff, the effective e⁻² length that accounts for finite pixel size. The solid line is a fit to the data given by the equation at the top of the figure. (b) When w₀/L is <0.5, the Gaussian approximation to Eq. 4 starts to break down, as seen by the best-fit Gaussian (line) to Eq. 4 (·) for w₀/L = 0.4. (c) Results of a stochastic simulation of spinning disk FCS measurements, showing the relative error with and without the finite pixel effect correction. The top curve is the bottom curve multiplied by β².