Inspection systems using metasurface and integrated optical systems for lithography

An inspection system comprising:

• an integrated optical system configured to receive, direct, and couple first, second, third, and fourth portions of illumination scattered by a target, the first, second, third and fourth portions having corresponding first, second, third, and fourth wavelengths, the integrated optical system comprising:
• a substrate;
• a waveguide system disposed on the substrate;
• a first grating coupler disposed on the substrate and configured to launch the first portion into the waveguide system based on the first wavelength;
• a second grating coupler disposed on the substrate and configured to launch the second portion into the waveguide system based on the second wavelength, the first and second wavelengths being the same;
• a third grating coupler disposed on the substrate and configured to launch the third portion into the waveguide system based on the third wavelength, the first and third wavelengths being different;
• and
• a fourth grating coupler disposed on the substrate and configured to launch the fourth portion into the waveguide system based on the fourth wavelength, the third and fourth wavelengths being the same;
• a first detector configured to receive a combination of the first and second portions via the waveguide system and to generate a first measurement signal comprising information of phase delay of the first and second portions;
• a second detector configured to receive a combination of the third and fourth portions via the waveguide system and to generate a second measurement signal comprising information of phase delay of the third and fourth portions;
• and
• a micro-structured illumination adjuster comprising first, second, third, and fourth micro-structured regions configured to direct corresponding ones of the first, second, third, and fourth portions to corresponding ones of the first, second, third, and fourth grating couplers.