Patent ID: 8379321

Claim:
An apparatus comprising optics that direct radiation from a scene along an optical axis, said optics having a longitudinal chromatic dispersion that is a function of a characteristic spectral signature for the scene, the characteristic spectral signature including a plurality of discrete wavelengths corresponding to a substantially same response, the optics being configured to focus each of the plurality of discrete wavelengths to a different focal point, the focal points being substantially equally spaced along the optical axis, so as to produce a polychromatic blur that, for an extended depth-of-field region, is substantially spatially constant along said optical axis; wherein said optics include a first lens having first and second optical surfaces on opposite sides thereof, and a second lens spaced from said first lens and having third and fourth optical surfaces on opposite sides thereof, one of said first, second, third and fourth optical surfaces being a diffractive optical surface with an aspheric base, and another of said first, second, third and fourth optical surfaces being aspheric.