Fresnel lenses consist of a flat surface with interspaced, concentric steps whereby each step corresponds to the surface of a conventional lens. Each step thereby acts as a refractive surface, much like a prism. This gives the Fresnel lens a common focal length equivalent to a traditional lens, but with a fraction of the thickness. Additionally, because the lens is so thin little light is lost by absorption. Although the image quality is generally poor, Fresnel Lenses can be desirable for use in condenser and lighting systems to collimate and collect light. Fresnel lenses can be used as magnifiers, but this is not recommended unless the thin profile and light weight is absolutely necessary.
Knight Optical offers a range of stock Fresnel Lenses made from PMMA Acrylic. Our stock range of PMMA Fresnel Lenses comes in two grades. Our “standard range” start from 5mm f.l x 5mm diameter aperture up to 254mm f.l x 152mm dia aperture.