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Principle of Fresnel Lenses

A Fresnel lens replaces the curved surface of a conventional lens with a series of concentric grooves molded into the surface of a thin, lightweight plastic sheet. The grooves act as individual refracting surfaces, looking like tiny prisms when viewed in cross section, bending parallel rays in a very close approximation to a common focal length. Because the lens is thin, very little light is lost by absorption, such as would be lost in condenser systems or emitter/detector setups (lenses should be mounted with grooves facing the distant light source). Fresnel lenses can also be used as magnifier or projection lenses. A traditional glass convex lens is thick, heavy and very expensive. Fresnel lenses can be made from plastic such as acrylic, PMMA, polyvinylchloride(PVC), polycarbonate(PC) and HDPE to be a thin, flat and low-cost solution.

▲Application of Fresnel      Lenses

Advantages of Fresnel lense

A Fresnel lens is less than 2mm thick. It can be designed and manufactured in very large sizes at a lower cost than traditional magnifiers. For example, a conventional glass lens 100mm thick at the edge would weigh over 20kg and cost thousands of dollars. Meanwhile, a Fresnel lens is far cheaper, and the light weight can reduce mounting and assembly costs in large optical systems like overhead projectors, Fresnel TV projections, rear projection Fresnel screens and Fresnel solar concentrators. In addition, a Fresnel lens with series of concentric grooves acts as individual refraction surfaces, like tiny prisms to bend parallel rays in a very close approximation to a common focal length. Because the lens is thin, very little light is lost by absorption. Fresnel lenses are most often used in light gathering applications, such as condenser systems or emitter/detector setups for solar power.

▲Mastering Molds