Systems and methods are provided for imaging a planar specular object such
as a semiconductor wafer. In one embodiment, an imaging system for
imaging a defect on a planar specular object includes a telecentric lens
having a sufficiently aspherical surface such that the telecentric lens
is substantially corrected for an optical aberration. The imaging system
also includes a telecentric stop including an aperture therein to block
light reflected from the planar specular object while allowing light
reflected from the defect to pass through the aperture. The imaging
system further includes a lens group having a system stop positioned
between the telecentric stop and the lens group. The lens group is
substantially corrected for the optical aberration independent of the
telecentric lens.