Abstract: Methods and apparatuses for evaluating overlay error on workpieces are disclosed herein. In one embodiment, a method includes generating a beam having a wavelength, and irradiating a first alignment structure on a first layer of a workpiece and a second alignment structure on a second layer of the workpiece by passing the beam through an object lens assembly that focuses the beam to a focus area at a focal plane. The beam is simultaneously focused through angles of incidence having (a) altitude angles of 0° to at least 150 and (b) azimuth angles of 0° to at least 900. The method further includes detecting an actual radiation distribution corresponding to radiation scattered from the first and second alignment structures, and estimating an offset parameter of the first and second alignment structures based on the detected radiation distribution.