An inspection system may be configured to inspect objects, such as
semiconductor wafers, using narrow-pulse broadband illumination. The
illumination may be obtained in some embodiments using a laser configured
to emit light into a material having a spectral broadening effect. The
inspection system can include various filters which may be selectively
placed in the illumination and/or imaging path in order to tune the
spectrum of light impinging on the wafer and the light that is detected.
The filters may include selectable filters, fixed filters, and filters
whose characteristics can be adjusted in-place. In some embodiments,
filters may be used to match the illumination/detection spectra of
different tools. Additionally, the broadband illumination may be tuned
between inspections and/or during inspections for best results. The
system may support Fourier filtering whereby light, related to repetitive
features of the object and in one or more wavelength sub-bands of the
illumination, may be filtered.