Fresnel Lens, Fresnel lenses, Lighthouse Fresnel Lens, Lighthouse Fresnel Optics, Green Fresnel

Fresnel Lens

Fresnel Lens

Fresnel Lens
It is a type of lens originally developed by French physicist Augustin-Jean Fresnel for lighthouses.The design enables the construction of lenses of large aperture and short focal length without the weight and volume of material that would be required in conventional lens design. Compared to conventional bulky lenses, the Fresnel lens is much thinner, larger, and flatter, capturing more oblique light from a light source.


Description
Compared to conventional bulky lenses, the Fresnel lens reduces the amount of material required compared to a conventional spherical lens by breaking the lens into a set of concentric annular sections known as "Fresnel zones", which are theoretically limitless. In the first variations of the lens, each zone was actually a different prism. Though a Fresnel lens might look like a single piece of glass, closer examination reveals that it is many small pieces. For each of these zones, the overall thickness of the lens is decreased, effectively chopping the continuous surface of a standard lens into a set of surfaces of the same curvature, with discontinuities in steps between them. In fact this product can be regarded as an array of prisms positioned in a circular fashion, with steeper prisms on the edges and a near flat convex center. Fresnel lenses are usually made of glass or plastic; their size varies from small to large. Since plastic lenses can be made larger than glass lenses, as well as being much cheaper and lighter, they are used to concentrate sunlight in multiple uses.






Application
Except for the lighthouse Fresnel optics, the solar energy is by far the Earth's most available energy source, easily capable of providing many times the total current energy demand with the Fresnel lens.


Solar Lighting System
Hybrid solar lighting is an active solar method of providing interior illumination. HSL systems collect sunlight using fresnel lens that concentrate the sun light and use optical fibers to transmit it inside the building to supplement conventional lighting. In single-story applications these systems are able to transmit 70%~80% of the direct sunlight received.


High Concentrated Photovoltaics
High concentration photovoltaics (HCPV) systems employ concentrating optics consisting of dish reflectors or lenses that concentrate sunlight to intensities of 300 suns or more. The conversion rate of compound based chip, such as GaAs/GAInP/Ge crystalline (III-V), can achieve around 30% to 41.6% max. HCPV is the compound based solution that provides the highest efficiency. There are two types of HCPV system: one is reflective type using either reflective dish or linear Fresnel technology, the other one is refractive type using circular Fresnel lens or lens array.


Stirling Engine
A Stirling engine is a heat engine operating by cyclic compression and expansion of air or other gas, the working fluid, at different temperature levels such that there is a net conversion of heat energy to mechanical work. The Stirling engine is noted for its high efficiency (up to 40%), quiet operation, and the ease with which it can use almost any heat source like concentrated light source from this type of lens.


Solar Cooker
Solar cooker is a device which uses only sunlight as its energy source. Because required no fuel to operate it. There are a variety of types of solar cookers. The fresnel type is used to concentrate sunlight into a hot spot and use some type of reflective metal to reflective the heat to a small cooking area. The temperature can reach up to 400°F or even higher. However, the cooker enable the sun to bake, boil, and steam a wide verity of food while enhancing the taste and benefiting the environment.









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