This article is also available in Japanese.

Fresnel lenses break a normal lens into a set of concentric annular sections known as Fresnel zones:



Fresnel lenses are lighter and occupy a smaller volume than the equivalent spherical lens. Fresnel lenses are used in lighthouse projectors, rear-projection TVs, and as solar concentrators, among many uses.

The vast majority of practical Fresnel lenses can be modeled using the Fresnel_1 object, which gives great control not only of optical properties but also of manufacturing parameters like pitch angle (the angle the inactive face makes to the lens body) and end caps. The supplied sample file {zemax root}\Samples\Non-sequential\Faceted objects\Fresnel lens radial structure.zmx shows a good example. Stray light caused by total internal reflection from the inactive face can be clearly seen.




Now it is sometimes required to model more complex Fresnel objects, typically for applications like TIR Lenses™ and other complex imaging applications:



Lenses like this can be easily made, using an Annular Aspheric Lens object for each Fresnel zone.