Patent ID: 8254031

Claim:
An apparatus, comprising: at least one substrate of optical material having a first surface and a second surface; at least one diffractive element disposed on the first or the second surface of said at least one substrate and configured to receive an input optical beam; at least one further diffractive element disposed on the first or the second surface; and at least one optically absorbing area within or disposed on said at least one substrate, wherein at least part of the input optical beam is diffracted in the diffractive element to provide at least one diffracted optical beam substantially within the first and the second surfaces, and at least part of the at least one diffracted optical beam is coupled out of the at least one substrate by diffraction in said at least one further diffractive element, thus providing an output optical beam out of said at least one substrate with an expanded exit pupil in one or two dimensions, wherein said input optical beam comprises K wavelength components and said at least one optically absorbing area is configured to absorb M pre-selected components out of the K wavelength components of said at least one diffracted optical beam and to propagate a selected component out of the K wavelength components of said at least one diffracted optical beam, such that the output optical beam comprises said selected component out of the K wavelength components, wherein K is an integer of at least a value of two and M is an integer between 1 and K−1.