Objective lens

An inspection system for inspecting a semiconductor substrate, the inspection system may include an inspection unit that comprises a partially blocking bright field unit and a non-blocking bright field unit; wherein the partially blocking bright field unit is configured to block any specular reflection that fulfills the following: (a) the specular reflection is caused by illuminating, along a first axis, of an area of the wafer, (b) the specular reflection propagates along a second axis, (c) the first axis and the second axis are symmetrical about a normal to the area of the wafer, and (d) the normal is parallel to an optical axis of the partially blocking bright field unit; and wherein the non-blocking bright field unit is configured to pass to the image plane any specular reflection that fulfills the following: (a) the specular reflection is caused by illuminating, along the first axis, of an area of the wafer, (b) the specular reflection propagates along the second axis, (c) the first axis and the second axis are symmetrical about the normal, and (d) the normal is parallel to the optical axis of the partially blocking bright field unit.