Fresnel lenses

Fresnel lenses consist of a series of concentric grooves etched onto one surface. Their thin, lightweight construction, available in small as well as large sizes, and excellent light gathering ability make them useful in a variety of applications. They are most often used in light gathering applications, such as condenser systems or emitter/detector setups.

The grooves in a Fresnel lens act as individual refracting surfaces, much like a group of tiny prisms. The grooved surfaces replace the continuous surface of a conventional lens into a set of surfaces with the same curvature.

Fresnel_03_DWG

They can also be used as magnifiers or projection lenses in illumination systems, and image formulation.

The Fresnel lens allows the construction of large-size and small optical focal length lenses without the bulk: the thickness and weight of the material needed to build them are lower than in a conventional spherical lens of equivalent dioptric power.

Groove Density

A lens’s groove density is measured in grooves per millimeter. Higher groove density (more grooves per millimeter) results in better quality images with lower optical efficiency, while lower density lenses yield better efficiency and poorer images. Less-dense lenses are most suitable for light gathering applications, while high density ones are more suited for imaging and projection.

Fresnel Lenses datasheet

Fresnel lenses by IODA s.r.l.

Fresnel lenses by IODA s.r.l.

Fr_F120_D96_RFR_F40_D114_R

These lenses are made of polyurethane optical, called REVO-01, which is a material developed by IODA in collaboration with Acomon (a Japanese multinational leader in ophthalmic monomers). This material allows the lens to last over time, being UV-resistant, and makes it suitable for both indoors and outdoors usages.
Link REVO-01

Historical Note
Augustin-Jean Fresnel — an early 19th century pioneer in the field of wave optics — is credited with the invention and application of grooved lenses. While working as a commissioner of lighthouses in France, Fresnel discovered that grooved lenses captured more oblique light than conventional ones, allowing lighthouse lights to operate more efficiently, use less material, and be visible over a greater distance.

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