Patent ID: 7206107

Claim:
An optical device comprising: an exit surface section; an input surface section to admit a light beam, the light beam comprising at least a first wavelength component and a second wavelength component; and at least a first layer and a second layer, each of the first and second layers comprising a first diffractive element and a second diffractive element, such that at least a part of the admitted light beam is diffracted in the first diffractive element in the first layer for providing a first diffracted portion; at least a part of the admitted light beam is diffracted in the first diffractive element in the second layer for providing a second diffracted portion; at least a part of the first diffracted portion is further diffracted in the second diffractive element in the first layer, thereby forming a first part of an exit beam exiting through the exit surface section; and at least a part of the second diffracted portion is further diffracted in the second diffractive element in the second layer, thereby forming a second part of the exit beam exiting through the exit surface section.