A telescope and beam expander assembly comprising: a primary telescope mirror; an optical element spaced apart from the primary mirror, the optical element including front and rear surfaces (108, 110), wherein an outward facing aspect of the rear surface is curved and is mounted opposite the primary mirror and includes a reflective portion that forms a secondary mirror to reflect gathered light from the primary mirror toward a focal point, wherein an inward facing aspect of the front surface includes a reflective portion that forms a secondary expander mirror configured to reflect a beam onto an inward facing aspect of the rear surface for beam expansion, wherein the optical element includes a monolithic body of optically-transmissive material on which the front and rear surfaces are located, wherein the reflective portion of the rear surface is reflective on both its outward aspect and its inward aspect to operate as both a secondary mirror for the primary mirror and as a primary beam expansion mirror; wherein the front surface includes an optically transmissive, non-reflective portion that is substantially flat; wherein the rear surface includes an optically transmissive, non-reflective portion for admitting a beam through the rear surface toward the reflective portion of the front surface for beam expansion; wherein the optical element defines an obscuration shadow with respect to the primary mirror, and wherein the non-reflective portion of the rear surface is positioned in the obscuration shadow; and an angled mirror for beam expansion within the obscuration shadow for reflecting a beam from an axis angled relative to an expander axis defined by the optical element into the optical element for beam expansion. a primary telescope mirror; an optical element spaced apart from the primary mirror, the optical element including front and rear surfaces (108, 110), wherein an outward facing aspect of the rear surface is curved and is mounted opposite the primary mirror and includes a reflective portion that forms a secondary mirror to reflect gathered light from the primary mirror toward a focal point, wherein an inward facing aspect of the front surface includes a reflective portion that forms a secondary expander mirror configured to reflect a beam onto an inward facing aspect of the rear surface for beam expansion, wherein the optical element includes a monolithic body of optically-transmissive material on which the front and rear surfaces are located, wherein the reflective portion of the rear surface is reflective on both its outward aspect and its inward aspect to operate as both a secondary mirror for the primary mirror and as a primary beam expansion mirror; wherein the front surface includes an optically transmissive, non-reflective portion that is substantially flat; wherein the rear surface includes an optically transmissive, non-reflective portion for admitting a beam through the rear surface toward the reflective portion of the front surface for beam expansion; wherein the optical element defines an obscuration shadow with respect to the primary mirror, and wherein the non-reflective portion of the rear surface is positioned in the obscuration shadow; and an angled mirror for beam expansion within the obscuration shadow for reflecting a beam from an axis angled relative to an expander axis defined by the optical element into the optical element for beam expansion.