Method and apparatus for high-throughput inspection of large flat patterned media using dynamically programmable optical spatial filtering

A system for inspecting a planar object having a periodic structure to indicate defects in said planar object comprising:

• a plurality of imaging channel heads, each imaging channel head comprising:
• an optical Fourier filter implemented by an electrically programmable spatial light modulator, said spatial light modulator being reconfigurable and having a contrast ratio sufficient to suppress periodic components of a transformed image of said planar object to less than optical sensor noise levels of a spatial image detector;
• a lens assembly of a sufficiently large field of view to interact with said spatial light modulator;
• a laser illumination system disposed to illuminate the planar object with coherent illumination and to produce optical energy intensity sufficient to saturate the spatial image detector absent the optical Fourier filter;
• and
• a feedback system associated with each said imaging channel head and responsive to output of the spatial image detector and operative according to an algorithm to computationally control the electrically programmable spatial light modulator to invoke an aligned filtering pattern sufficient to suppress the periodic components of the transformed image.