Diffraction grating array for wide-angle illuminateon

An article, comprising:

• a plurality of optical sources being configured to provide multiple incident optical signal beams of input illumination, each multiple incident optical signal beam characterized by a corresponding incident wavelength within an operational wavelength range;
• and
• a grating substrate being configured to produce far-field illumination from the input illumination passing therethrough, the grating substrate bearing a contiguously arranged set of multiple diffraction gratings, each of the optical sources being arranged to direct a corresponding one of the incident optical signal beams onto the grating substrate and being configured to illuminate a corresponding illuminated subset of the multiple diffraction gratings, wherein:
• (a) the grating substrate is substantially transparent over the operational wavelength range of the multiple incident optical signal beams providing the input illumination passing through the grating substrate, the set of multiple diffraction gratings is positioned on a surface of the grating substrate or within the grating substrate, each diffraction grating of the set is characterized by a corresponding grating wavevector, the multiple diffraction gratings are positioned and arranged on or in the grating substrate so that each diffraction grating of the set differs from at least one other diffraction grating of the set with respect to the corresponding grating wavevectors;
• (b) the multiple diffraction gratings are positioned and arranged on or in the grating substrate so that the multiple incident optical signal beams are each incident along a corresponding incident propagation direction on a corresponding non-empty illuminated contiguous subset of the multiple diffraction gratings, the multiple diffraction gratings are positioned and arranged on or in the grating substrate so that corresponding diffracted portions of the multiple incident optical signal beams are each diffracted into one or more corresponding output optical signal beams by non-zero-order diffractive transmission by the corresponding diffraction gratings of the corresponding illuminated contiguous subset of the multiple diffraction gratings, the output optical signal beams each being characterized by the corresponding incident wavelength, a corresponding output propagation direction, and a corresponding output beam far-field divergence;
• and
• (c) the multiple diffraction gratings are collectively positioned and arranged on or in the grating substrate and the corresponding optical sources are positioned and arranged so that angular separation of the output propagation direction of each one of the output optical beams, from the output propagation direction of at least one other of the output optical beams, is less than the corresponding output beam far-field divergence of that optical beam, so that collectively the output optical beams and zero-order-transmitted portions of the incident optical beams result in a solid angle of the far-field illumination that is contiguous illumination being a composite superposition of all of the output optical beams arising from the multiple diffraction gratings acting on the multiple incident optical signal beams, wherein (i) the solid angle of the far-field illumination is larger than that resulting from the zero-order-transmitted portions of the incident optical beams alone, (ii) the far-field illumination exhibits a spatial variation that differs from that resulting from the zero-order-transmitted portions of the incident optical beams alone, or (iii) both.