A pancake lens block, comprising: an optical element (130, 132, 140) configured to transmit at least a portion of radiation from a radiation source; and a shaped reflective polarizer spaced at a distance from the optical element; wherein the shaped reflective polarizer is configured to provide achromatic optical power to the pancake lens block; wherein the optical element comprises: a first retarder having a first axis of orientation, where the first retarder is configured to selectively transmit a portion of the radiation from the radiation source; a partial reflector that receives the portion of radiation from the first retarder and transmits the portion of radiation; and a second retarder having a surface at a distance from the shaped reflective polarizer, where the second retarder is oriented to a second axis of orientation that is substantially orthogonal to the first axis of orientation, and where the second retarder transmits the portion of radiation from the partial reflector; wherein the shaped reflective polarizer is configured to reflect the portion of radiation transmitted by the second retarder back to the partial reflector through the second retarder, where the partial reflector reflects a second portion of the radiation from the second retarder back to the shaped reflective polarizer; wherein the shaped reflective polarizer comprises a lens and a wire-grid polarizer, characterized in that the wire-grid polarizer comprises: (i) a bolstering substrate, (ii) a wire-grid substrate coupled to the bolstering substrate, and (iii) wire-grids disposed on the wire-grid substrate; wherein the bolstering substrate provides mechanical support to the wire-grid polarizer and maintains a polarization state of the portion of radiation transmitted by the second retarder; wherein the lens has a convex surface having a radius of curvature; wherein the wire-grid polarizer (932, 934) is disposed on the convex surface of the lens; wherein a thickness of the bolstering substrate is at least partially based on the radius of curvature; and r further characterized in that a cavity between the optical element (130, 132, 140) and the shaped reflective polarizer is filled with a nanovoided material. an optical element (130, 132, 140) configured to transmit at least a portion of radiation from a radiation source; and a shaped reflective polarizer spaced at a distance from the optical element; wherein the shaped reflective polarizer is configured to provide achromatic optical power to the pancake lens block; wherein the optical element comprises: a first retarder having a first axis of orientation, where the first retarder is configured to selectively transmit a portion of the radiation from the radiation source; a partial reflector that receives the portion of radiation from the first retarder and transmits the portion of radiation; and a second retarder having a surface at a distance from the shaped reflective polarizer, where the second retarder is oriented to a second axis of orientation that is substantially orthogonal to the first axis of orientation, and where the second retarder transmits the portion of radiation from the partial reflector; a first retarder having a first axis of orientation, where the first retarder is configured to selectively transmit a portion of the radiation from the radiation source; a partial reflector that receives the portion of radiation from the first retarder and transmits the portion of radiation; and a second retarder having a surface at a distance from the shaped reflective polarizer, where the second retarder is oriented to a second axis of orientation that is substantially orthogonal to the first axis of orientation, and where the second retarder transmits the portion of radiation from the partial reflector; wherein the shaped reflective polarizer is configured to reflect the portion of radiation transmitted by the second retarder back to the partial reflector through the second retarder, where the partial reflector reflects a second portion of the radiation from the second retarder back to the shaped reflective polarizer; wherein the shaped reflective polarizer comprises a lens and a wire-grid polarizer, characterized in that the wire-grid polarizer comprises: (i) a bolstering substrate, (ii) a wire-grid substrate coupled to the bolstering substrate, and (iii) wire-grids disposed on the wire-grid substrate; wherein the bolstering substrate provides mechanical support to the wire-grid polarizer and maintains a polarization state of the portion of radiation transmitted by the second retarder; wherein the lens has a convex surface having a radius of curvature; wherein the wire-grid polarizer (932, 934) is disposed on the convex surface of the lens; wherein a thickness of the bolstering substrate is at least partially based on the radius of curvature; and r further characterized in that a cavity between the optical element (130, 132, 140) and the shaped reflective polarizer is filled with a nanovoided material.