Fresnel lenses can be made very thin.Use plastic materials.Volume weight.Fresnel lenses are usually used, and when the diameter of the lens is more than 3 or 4 inches (76mm or 100mm), the manufacturing cost of glass lenses is considerable if used in display systems.Low cost.That is, the weight and space occupied by the lens should not be too large. The introduction of Fresnel lens in the back-projection display,

Once larger size lenses are needed in an optical system, another factor to consider.And the thermo-mechanical properties of the plastic material are limited because of its specific structural surface.

Fresnel optical lens plastic Fresnel lens is also not suitable for all large size applications, resulting in its precision can not meet certain technical requirements.For example, large size lenses are usually required in astronomical equipment, but Fresnel lenses are quite perfect in display applications: the next chapter will explain the application of Fresnel lenses in the lower back projection display.