Transmissive, non-imaging Fresnel types of reflective radiation concentrators revisited

The principles of operation are described for a broadband transmissive radiation concentrator system comprised of reflective nested frustoconical shells with a common axis. The theory for such a system is first developed and then extended to that of a reflective spiral geometry, a system which is more readily realised in a practical device. Proof of principle of such a reflective Fresnel spiral scheme is demonstrated experimentally by two distinctive types of design for solar concentrators with promising radiation collection efficiency.