Interrogation optical beams are focused or otherwise shaped for delivery to a target that includes one or more tooling balls so as to have a beam radius of curvature corresponding to a tooling ball radius. Focus values can be stored in a look-up table and can include two beam focus conditions that produce a selected beam focus. The two beam focus conditions are associated with a common beam curvature. The focus conditions are associated with beam curvatures within and without a Rayleigh range from a beam waist.