نتایج جستجو برای: fresnel lenses
تعداد نتایج: 15913 فیلتر نتایج به سال:
Flat lenses when compared to curved surface lenses have the advantages of being aberration free and they offer a compact design necessary for a myriad of electro-optical applications. In this paper we present flat and ultra-thin lenses based on graphene, the world’s thinnest known material. Monolayers and low number multilayers of graphene were fabricated into Fresnel zones to produce Fresnel z...
A Fresnel zone plate lens can be constructed using a dye-doped liquid crystal filled cell and photo-induced alignment techniques. Light passing through a Fresnel zone patterned photo-mask causes the dye-doped liquid crystal to align in such a way to produce odd and even zones on the lens. Diffraction of incident light through the odd and even zones of the lens allows the light to constructively...
Micromachined Vertical Three-Dimensional Micro-Fresnel Lenses For Free-Space Integrated Micro-Optics
We report the first fabrication of vertical three-dimensional micro-Fresnel lenses with polysilicon materials by surface micromachining technique. Micro-Fresnel lenses play a very important role in micro-optics because of their thin film structures and their ability to achieve very short focal lengths. Although micro-Fresnel lenses have been studied and well understood [ 11, the lens planes usu...
The Fresnel lens can be used in a wide variety of applications. The basic principles of the Fresnel lens are review ed and some practical examples are des cribed. There are definite advantages and tradeoffs that should be considered when deciding if a Fresnel lens is the appropri ate component to use in a design. Some basic optimization rules are presented which may facilitate a first order ...
Achromatic combinations of a diffractive phase Fresnel lens and a refractive correcting element have been proposed for x-ray and gamma-ray astronomy and for microlithography, but considerations of absorption often dictate that the refractive component be given a stepped profile, resulting in a double Fresnel lens. The imaging performance of corrected Fresnel lenses, with and without stepping, i...
We present a novel Nipkow disk design for terahertz (THz) single pixel imaging applications. A 100 mm high resistivity (ρ≈3k-10k Ω·cm) silicon wafer was used for the disk on which a spiral array of twelve 16-level binary Fresnel lenses were fabricated using photolithography and a dry-etch process. The implementation of Fresnel lenses on the Nipkow disk increases the THz signal transmission comp...
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