Lithographic apparatus, inspection system, and method of implementing parallel sensor-heads with a common radiation source

A lithographic apparatus comprising:

• an illumination system configured to illuminate a pattern of a patterning device;
• a projection system configured to project an image of the pattern onto a substrate to form a plurality of targets on the substrate;
• and
• an inspection system configured to inspect the plurality of targets, the inspection system comprising:
• a broadband radiation system configured to generate source radiation having a first set of narrowband wavelengths distributed within an operating bandwidth of the inspection system and a second set of narrowband wavelengths distributed within the operating bandwidth, wherein a narrowband wavelength of the first set is proximal to a narrowband wavelength of the second set;
• an optical system configured to direct a first portion of the source radiation toward a first target of the plurality of targets to generate first scattered radiation and to direct a second portion of the source radiation toward a second target of the plurality of targets to generate second scattered radiation;
• a wavelength separator system configured to separate narrowband wavelengths of the first and second scattered radiation;
• and
• a detector system configured to receive the first and second scattered radiation and to generate first and second measurement signals based on the first and second scattered radiation, respectively.