Later Applications
Glass Fresnel assemblies were displaced in navigation by compact sealed-beam and LED optics, and surviving lenses are now largely museum pieces, some of considerable value. The principle, however, outlived the artefact.
Moulded acrylic made thin Fresnel surfaces cheap, and they are now ubiquitous in places where light must be gathered or spread but no image is required: the condenser in an overhead projector, the fly-eye arrays in theatrical and film lighting, the wide-angle patch stuck to the rear window of a van, the collimator in front of a traffic signal, and the lens over the pyroelectric sensor in a domestic motion detector, which divides its field of view into fan-shaped zones so that a moving body crosses them in sequence.
Solar concentrators use large Fresnel sheets to focus sunlight onto photovoltaic cells or thermal receivers, returning the design to the problem of collecting as much light as possible with as little material as possible, which is what Fresnel set out to solve.