A linearly reflecting trough
concentrator that receives spectral energy, preferably visible and near-
infrared solar energy spectra, and linearly reflects that energy onto a smaller area on one side of the device, thereby concentrating the energy. The linearly reflecting trough
concentrator has the geometry of a single slope-relief interval in a
Fresnel lens, and in preferred embodiment comprises an array of heliostatic facets connected continuously to form the base of the trough, a non-imaging focal point where a photonic
receiver is located, and a relief surface to connect the heliostatic array to the
receiver location. When spectral energy enters the trough at an angle normal to the array's horizontal reference, the
concentrator linearly reflects energy to one side of the device where an energy
receiver is mounted. The concentrator comprises an array of heliostats oriented according to the negative profile of two interleaved linear
Fresnel lens, where the slope of one is the relief of the other. The concentrator reflects energy above and to each side of the device. Optionally using a reflecting
projector on one side of the device, energy is then doubly concentrated to the other side. The device offers higher concentration ratios with an equivalent trough depth than prior art reflective trough concentrators. The device requires less depth and offers a lower-profile than prior art reflecting concentrators with the same degree of concentration.