Free-form Fresnel Structures for Beam Shaping

Free-form Fresnel structures are optical elements which modify the incident beam by collimating, broadening, bending, or generally shaping the beam. The underlying design paradigm is that the beam can be represented by a unique wave front – for instance, light emitted from a point source. Fresnel structures can consist of one or more surfaces, depending on application. In most cases, the surfaces comprise rings or facets with optical functionality, connected by steep flanks without such functionality. The main advantages of Fresnel structures are compactness, versatility in design, and ease of fabrication. In most practical applications, Fresnel structures are not illuminated by point sources, but extended light sources. This may cause stray light which requires careful analysis. This talk presents design approaches of free-form Fresnel structures with and without rotational symmetry. We discuss typical applications in automotive industry for light collimation, wide angle deflection, and beam shaping. Additionally, we suggest strategies for stray light reduction.