The design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a lens of conventional design.
The Fresnel lens design allows for significant reductions in lens thickness (as well as weight and volume) but at the expense of reduced image quality, which is why sophisticated imaging equipment such as monocular cameras and digital cameras still use traditional heavy lenses.
Fresnel lenses are often made of glass or plastic and range in size from large (old beacons, sizes in meters) to medium (reading magnifiers, slide projections) to small (single-eye camera focusing screens, micro-optics). In most cases, they are thin, flat, and tough, about 3-5 mm thick.
Since the use of a Fresnel lens to project light reduces the image quality, it is generally used where the imaging quality is less demanding or general lenses cannot be used. The inexpensive Fresnel lens is generally molded or molded from clear plastic and used on lens-type projectors, rear projection televisions, and portable magnifiers. At the same time it is also applied to traffic lights. Fresnel lenses are also used to correct some visual impairments such as strabismus.
Since the plastic Fresnel lens can be made larger than glass, lighter and more economical at the same time, he is used in solar cookers to collect sunlight or solar water heaters.
Perhaps the most widespread application of Fresnel lenses is in automotive headlights. It allows the headlights to be tilted downward by the parallel light originally reflected by the concave mirror, which can not only illuminate the road ahead but also prevent glare to the front and the opposite person. Taking into account factors such as price, weight and impact resistance, newer models have eliminated glass Fresnel lenses and instead adopted multi-faceted mirrors and flat polycarbonate lenses. However, Fresnel lenses are still widely used in car taillights and reversing lights.
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