Focus

Focus models the optical effect of a focusing element, i.e., it changes the curvature of an incident complex field. More precisely, Focus applies a unit-amplitude quadratic-phase factor to the incident complex field. The sign convention is that positive "focusDistance" makes the wavefront more convergent, while negative "focusDistance" makes the wavefront less convergent, regardless of the direction of propagation. The focus is applied to both incoming and outgoing light that passes through the Focus module.