Patent ID: 7327908

Claim:
An optical apparatus, comprising an optical element having at least one set of diffractive elements and a sensing region, wherein: the diffractive elements of the set are collectively arranged so as to comprise spectral and spatial transformation information; the diffractive elements of the set are collectively arranged so as to transform at least a portion of an input optical signal into an output optical signal according to the spectral and spatial transformation information so that a spatial wavefront of the input optical signal differs from a spatial wavefront of the output optical signal, the input optical signal propagating from an input optical port, the output optical signal propagating to an output optical port, the input optical signal or the output optical signal propagating within the optical element so as to be successively incident on the diffractive elements of the set; the sensing region is arranged for receiving a sample material so that the input optical signal or the output optical signal at least partly spatially overlaps a portion of the sample material in the sensing region; and the diffractive element set and the sensing region are arranged so that the spectral or spatial transformation information varies according to at least one optical property of the received sample material.