System and method for generating multi-channel tunable illumination from a broadband source

A metrology system, comprising:

• an illumination source configured to generate an illumination beam having an input spectrum;
• a multi-channel spectral filter, comprising:
• two or more filtering channels having two or more spectral transmissivity distributions, wherein at least one of the two or more filtering channels includes a spectral filter;
• and
• a channel selector including at least one of an optical modulator or a polarization rotator configured to switch selected intensity fractions of the illumination beam into one or more selected filtering channels of the two or more filtering channels without modifying the input spectrum of the illumination beam, wherein the selected intensity fractions of the illumination beam directed to the one or more selected filtering channels have the same input spectrum as the illumination beam to provide independent filtering of the input spectrum by the one or more selected filtering channels, wherein the one or more selected filtering channels generate one or more filtered output beams based on the spectral transmissivity distributions of the one or more selected filtering channels;
• at least one beam combiner to combine illumination from the two or more filtering channels to a single optical column;
• a single focusing element to direct illumination from the two or more filtering channels in the single optical column to a sample;
• at least one adjustable beam deflector to selectively adjust an optical path of illumination from at least one filtering channel of the two or more filtering channels through the single focusing element to illuminate the sample at two or more selected locations;
• and
• two or more detectors to capture radiation from the two or more selected locations of the sample.