Seamless fusion of telecentric brightfield and annular darkfield illumination

摘要

Described is an illumination system for an area inspection apparatus. The described illumination provides telecentric bright field and annular dark field light that are seamlessly fused together. In one or more embodiments, the illumination system incorporates a unified optical lens assembly that combines different lenses that image illuminations positioned at different planes to a single plane in a seamless way. In one or more embodiments, the different parts of the illumination system have common aperture stop, therefore no vignetting is present in the optical path resulting in high quality of the optical images acquired by the inspection system.