What is Fresnel lens? What is its used for?

Fresnel lens summary

Fresnel lenses are portable and lightweight sheets used for light gathering or magnifying. The frensel lens was first invented by a French physicist namely Augustin-Jean Fresnel. Augustin Fresnel first used this lens design to build a glass Fresnel lens - lighthouse lens in 1822.

Unlike typical spherical or aspherical optical lenses, fresnel lenses are composed of a series of concentric grooves etched into one side of a sheet of plastic. A fresnel lens is a thin, flat optical lens which consists of a series of a series of small narrow concentric grooves on the surface of a lightweight plastic sheet in order to reduce the thickness, weight and cost. Each groove is at a slightly different angle than the next and with the same focal length in order to focus the light toward a central focal point. Every groove can be considered as an individual small lens to bend parallel Fresnel light waves and focus the light. The lens actually eliminates some spherical aberration.

The Fresnel lens is a special optical lens. lt can now be made from plastic such as acrylic fresnel lens, PMMA, polyvinyl cholride (PVC), polycarbonate (PC) and HDPE. A traditional glass convex lens would be thick, heavy and very expensive, but a plastic Fresnel lens is a thin, flat, lightweight and low cost alternative.

A high groove density has a better quality projection image. The Fresnel lens is a good solution for quality image and efficiency at a significantly lower cost. The Fresnel lens is usually corrected for spherical aberration.

What is a fresnel lens used for?

Fresnel lens, a succession of concentric rings, each consisting of an element of a simple lens, assembled in proper  relationship on a flat surface to provide a short focal length. The Fresnel lens is widely used in our daily life as light collector and fire starter. Particularly in lighthouses and searchlights to concentrate the light into a relatively narrow beam. 

Field lenses (fresnel screen 'brighteners")

A Fresnel lens can be used to redirect the light at the edges of a frosted rear-projection display screen toward the viewer's eyes, thus eliminating the "hot spot" often observed in such screens by brightening the edges of the display.  Screens of this type include camera focusing screens.  The grooves must face the light source in this application; the grooves often must therefore face the shorter conjugate, an exception to the usual rule.

Conjugates for the field lens should be the distance from the projector lens on the grooved side, and the distance to the viewer on the frosted sdie. Tehao can supply suitable lenses with the plano side either optically polished or frosted. 

Applications of fresnel lens

The applications for Fresnel lenses include lighting, fresnel lamp, lighthouse, overhead projector, Fresnel magnifier, Fresnel TV projection, condenser system, camera fresnel spotlight, automobile headlight, fresnel lens solar energy , rear projection Fresnel screen, passive motion detector, traffic sign, fresnel lens photovoltaic, fresnel solar concentrator, collimator, fresnel flight simulator, optical landing system and LED magnifier.

Applications of fresnel lens

The applications for Fresnel lenses include lighting, fresnel lamp, lighthouse, overhead projector, Fresnel magnifier, Fresnel TV projection, condenser system, camera fresnel spotlight, automobile headlight, fresnel lens solar energy , rear projection Fresnel screen, passive motion detector, traffic sign, fresnel lens photovoltaic, fresnel solar concentrator, collimator, fresnel flight simulator, optical landing system and LED magnifier.

Types of fresnel lenses

Types of Fresnel lens : positive Fresnel lens, negative Fresnel lens, Fresnel lens array, cylindrical Fresnel lens, circular Fresnel lens, linear Fresnel lens, lenticular Fresnel lens, diffraction Fresnel, Fresnel reflection, Fresnel beamsplitter and Fresnel prism.

Advantages of fresnel lens

The Fresnel lens can be designed and manufactured in very large sizes with light weight due to less than 4mm thickness, so the cost will be lower than traditional magnifiers. ln contrast, a conventional glass lens would be 200mm thick at the edge, weigh over 50kgs and cost thousand of dollars.

Significantly reduced lens thickness results in a substantial savings in material cost. Fresnel lenses can reduce weight, which reduces mounting and assembly cost. Extremely giant Fresnel lens up to 1000mm can be used to replace a very expensive conventional mirror assemblies in large optical systems.

Full page 3x magnifying sheet with black border magnify up to 300%. It is considered the most comfortable magnification for reading small prints, ideal for Viewing and checking tiny hobby and crafting materials, small electronic gadget parts such as screws and pins.

Design of fresnel lens

To determine the optical Fresnel lens design equation, all of the parameters are determined for each individual application. Several Fresnel zone formulas are used in Fresnel technologies for precision diamond tooling machines and electroforming and molding processes.