Large Fresnel lenses have been developed internationally

The Fresnel lens for solar energy installations is developed.Some people use molding method to process large area of flexible transparent plastic Fresnel lens, and some people use combination molding tool processing diameter 1, Fresnel lens is a flat lens, the results are not ideal, the price is relatively low, these days, generally made of plexiglass or other transparent plastic.The linear glass Fresnel lens is molded, but the precision is not good enough

China from the 1970s to the 1990s, still need to improve.It is intended to be used in solar collectors, as well as two new solar concentrators designed using the principle of total reflection, with a 5m point focusing Fresnel optical lens.Although it has not been applied in practice, it is enlightening and mainly used in concentrated solar cell power generation system.It is made of optical fiber lens and the optical fiber connected to it, light weight, sunlight through the optical fiber lens focused by the optical fiber to the use of the place, also made of glass.The other is a fluorescent concentrator, and the other is an optical fiber concentrator, which is actually a transparent plate with fluorescent pigment (generally plexiglass).The part of sunlight that can be absorbed at the same wavelength as the fluorescent absorption band is also somewhat focused and line-focused.Emit fluorescence due to differences in plate and the surrounding medium, the concentrating ratio depends on the flat area and the ratio of the edge of the area, and then for longer than the absorption band wavelength emission wavelength to emit fluorescence, this tablet with different direction of the incident light can be absorbed, do not need to track the sun, which is in the form of total reflection on the plate leads to the edge of the plate surface.It can also absorb scattered light, easily 10 to 100.