Fresnel lens is a branch of lens. Compared with other lenses, Fresnel lens has the advantages of small volume, light weight and compact structure. At the same time, it has good focusing property and imaging performance which is no inferior to other lenses. Therefore, it has been widely used in various fields such as industrial production and civil use.
1. Projection display
Fresnel lens adjusts the beam light source emitted by the light source to parallel light, which significantly improves the brightness around the display panel, eliminates the sun spot effect, and improves the brightness uniformity of the whole display. Fresnel lenses are usually used in conjunction with other display elements, such as cylindrical lens.
2. Solar Fresnel lens
A typical solar Fresnel lens is oriented toward the cell, which is opposite to the long conjugate direction in the collimating application.Therefore, it is unnecessary to reduce the spherical error of the image.
This type of Fresnel lens is usually regarded as a non imaging lens because the focal length of the effective area passing through the lens is fixed. The main function of this method is to maximize the solar radiation to the cell, which is used to convert it into electric power.
3. Magnifying lens
Generally speaking, a magnifying glass is a focusing lens to form a virtual upright image. Fresnel magnifier is an ultra-thin magnifier made of transparent plexiglass. The minimum thickness of Fresnel magnifier made of PVC can be between 0.45mm and 0.90mm. Different from ordinary magnifiers, its surface is covered with tiny fringes, and many convex lenses (referred to as circular rings) are included in its vortex fringe, which makes the ray bend through it (this is what we called diffraction phenomenon), thus forming an enlarged image.