Twin axis fresnel lens - has prismatic surface with each step contg. smaller steps running at right angles

摘要

The fresnel lens has a smooth surface and a second surface with parallel steps (1), each of which forms a prism with the first smooth surface. The steps themselves have smaller steps (3) running at right angles to form a secondary prismatic surface. The width of the secondary steps is a tenth (or smaller) of the primary steps. The shape of the complete unit may be plane or cylindrical. The secondary steps may be formed from a separate foil strip which is then glued onto the primary steps. The whole unit may be used to concentrate solar energy onto a focal plane and then to diffract the resultant beam vertically. USE/ADVANTAGE - For solar to electrical energy conversion. Does not need to track vertical movement of sun.