Fig. 10.8 — Force measurement from drift velocity

Schematic view of the propagator ρ(Δz; z₀, Δt), which gives the distribution of the particle position increments Δz from its 􏰚initial position z₀ after a time step Δt. The distribution is Gaussian for sufficiently small t with standard deviation (2D(z₀)Δt)^0.5. The force can be estimated from the measured drift according to Eq. (10.29).