Patent ID: 7477383

Claim:
A dark field illuminating system for illuminating an object plane at non-perpendicular incidence useful in an inspection system for inspecting an object, said dark field illuminating system comprising: an imaging system including an imager operative to image said object, while said object is illuminated; and an illuminating source beam having a cross section of a form such that it reduces elongation of an impingement area of said beam on said object plane generated by virtue of the angle of incidence of said illuminating source beam on said object plane, said angle of incidence being less than 90 degrees relative to said object plane, wherein a numerical aperture (NA) value of said illuminating source beam along the length of an elongated impingement area of said illuminating source beam is essentially the same as an NA value of said illuminating source beam along an axis extending perpendicular to said length of said elongated impingement area.