A sensing device with an odd-symmetry grating projects near-field spatial modulations onto a closely spaced photodetector array. The grating includes upper and lower features that define boundaries of odd symmetry. The features include upper and lower segments of various widths on opposite sides of each boundary, the upper segments at a height sufficient to induce one half wavelength of retardation in the band of interest relative to the lower segments. The resultant interference produces the spatial modulations for capture by the array. Photographs and other image information can be extracted from the captured data.
Phase gratings with odd symmetry for high-resolution lensed and lenseless optical sensing