An optical apparatus, comprising: a plurality of lenses including at least one thin birefringent lens and a polarizer, wherein the at least one thin birefringent lens is oriented with its ordinary and extraordinary axes perpendicular to each other and both lying in a plane of the lens orthogonal to a direction of light propagation through the lens, wherein the at least one thin birefringent lens comprises a nano-structured non-birefringent meta-material wherein the birefringent properties are imparted by patterns encoded in the nano-structures, and wherein the patterns encode spherical quadratic phase patterns providing different focal lengths to the light polarized parallel to the ordinary and extraordinary axes, wherein the at least one thin birefringent lens patterns further encodes one or more phase patterns other than spherical quadratic phase patterns to optimize the optical apparatus, and wherein the plurality of lenses are configured to, in use,: receive electromagnetic radiation from an object, wherein the electromagnetic radiation is incoherent light and comprises light component polarized parallel to the ordinary axis and light component polarized parallel to the extraordinary axis of the at least one thin birefringent lens; split, by transmission through the at least one thin birefringent lens, the received electromagnetic radiation into two or more differentially modulated electromagnetic waves propagating in a common path, wherein the differentially modulated electromagnetic waves comprise waves polarized parallel to the ordinary and extraordinary axes having different spherical curvatures; and provide, by passing the differentially modulated electromagnetic waves through the polarizer, for the differentially modulated electromagnetic waves to create electromagnetic interference. a plurality of lenses including at least one thin birefringent lens and a polarizer, wherein the at least one thin birefringent lens is oriented with its ordinary and extraordinary axes perpendicular to each other and both lying in a plane of the lens orthogonal to a direction of light propagation through the lens, wherein the at least one thin birefringent lens comprises a nano-structured non-birefringent meta-material wherein the birefringent properties are imparted by patterns encoded in the nano-structures, and wherein the patterns encode spherical quadratic phase patterns providing different focal lengths to the light polarized parallel to the ordinary and extraordinary axes, wherein the at least one thin birefringent lens patterns further encodes one or more phase patterns other than spherical quadratic phase patterns to optimize the optical apparatus, and wherein the plurality of lenses are configured to, in use,: receive electromagnetic radiation from an object, wherein the electromagnetic radiation is incoherent light and comprises light component polarized parallel to the ordinary axis and light component polarized parallel to the extraordinary axis of the at least one thin birefringent lens; split, by transmission through the at least one thin birefringent lens, the received electromagnetic radiation into two or more differentially modulated electromagnetic waves propagating in a common path, wherein the differentially modulated electromagnetic waves comprise waves polarized parallel to the ordinary and extraordinary axes having different spherical curvatures; and provide, by passing the differentially modulated electromagnetic waves through the polarizer, for the differentially modulated electromagnetic waves to create electromagnetic interference. receive electromagnetic radiation from an object, wherein the electromagnetic radiation is incoherent light and comprises light component polarized parallel to the ordinary axis and light component polarized parallel to the extraordinary axis of the at least one thin birefringent lens; split, by transmission through the at least one thin birefringent lens, the received electromagnetic radiation into two or more differentially modulated electromagnetic waves propagating in a common path, wherein the differentially modulated electromagnetic waves comprise waves polarized parallel to the ordinary and extraordinary axes having different spherical curvatures; and provide, by passing the differentially modulated electromagnetic waves through the polarizer, for the differentially modulated electromagnetic waves to create electromagnetic interference.