A method of concentrating directional radiant energy using reflective optics and receivers that convert that energy wherein the receivers are situated in the body of the reflector on risers parallel to the direction of radiant energy, each said riser bounded by at least one parabolic mirror lying closer and another lying farther from the energy source, where the focus or foci of said mirrors lie substantially in the direction faced by the receiver situated in said riser. The reflector geometries include ones in which the mirrors are parabolic cylinder sections and require only one-axis tracking to focus, and ones in which the mirrors are paraboloid sections and require two-axis tracking to focus sunlight.