1. A camera for sensing incident light over a wavelength band of interest, the camera comprising: a photodetector array in a path of the incident light; and a phase grating overlying the photodetector array and disposed in the path to illuminate a pattern area at the photodetector array, the phase grating including: curved boundaries of odd symmetry, intersecting to form a spiral, separating stepped features on opposite sides of each boundary, the stepped features on the opposite sides of each boundary offset from the array by one half of one of the wavelengths of the wavelength band of interest, plus an integer number of the one of the wavelengths, to produce curtains of destructive interference that extend to the photodetector array.