Results 241 to 250 of about 32,036 (281)

Switchable Fresnel lens based on micropatterned alignment

Optics Letters, 2013
In this Letter we disclose a method to fabricate a liquid crystal (LC) Fresnel zone lens (FZL) with higher efficiency. The LCFZL, based on alternate twisted nematic (TN) and planar aligned (PA) regions, has been prepared by means of a two-step photo-alignment process.
Wang, Xiaoqian, Srivastava, Abhishek Kumar, Chigrinov, Vladimir G, Kwok, Hoi Sing   +3 more
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Nine-sector three-stage Fresnel lens concentrator

Applied Optics, 2018
In this paper, we design a three-stage Fresnel lens concentrator with a low f number. The proposed concentrator consists of a primary optical element (POE) and a second optical element (SOE). The nine-sector three-stage Fresnel lens is composed of three types of triangular prisms: the refractive triangular prism, single total internal reflection ...
Yong-Da, Chen, Shin-Han, Tu, Hwen-Fen, Hong, Chun-Yi, Chen, Jui-Wen, Pan   +4 more
openaire   +2 more sources

Reflections from a Fresnel lens

Physics Education, 2004
Reflection of light by a convex Fresnel lens gives rise to two distinct images. A highly convex inverted real reflective image forms on the object side of the lens, while an upright virtual reflective image forms on the opposite side of the lens. I describe here a set of laser experiments performed upon a Fresnel lens.
openaire   +1 more source

ZnS micro-Fresnel lens and its uses

Applied Optics, 1990
A micro-Fresnel lens replication method by inorganic material deposition has been developed. A ZnS micro-Fresnel lens and a completely flat micro-Fresnel lens have been made by this method. The ZnS microFresnel lens stability characteristics are improved for temperature, humidity, and focusing.
H, Hosokawa, T, Yamashita
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Fresnel lens analysis for solar energy applications

Applied Optics, 1981
In this paper we analyze an arbitrarily shaped lineal Fresnel lens acting either as sole concentration stage or as the first stage of a two-stage concentration system in which the second stage considers the first as a Lambertian source. We determine the gain and position of the lens for all possible configurations, and we demonstrate that a curved lens
E, Lorenzo, A, Luque
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Recursive fresnel lens

This research introduces a novel optical framework that extends the Fresnel lens concept into a fractal, golden-ratio-based geometry, capable of producing multi-depth focusing and artificial lensing effects without gravitational or conventional refractive means.
openaire   +1 more source

60 GHz planar fresnel zone lens

2015 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, 2015
In this paper, we present the design guidelines of a planar Fresnel zone lens, where each zone has a certain permittivity. The different permittivities are realized by perforating a dielectric of higher permittivity. We designed a lens that adds 13 dB of gain to a patch antenna.
Xiaozhou Wang, Michael Jenning, Dirk Plettemeier   +2 more
openaire   +1 more source

Fresnel lens on new photosensitive material

SPIE Proceedings, 2005
In this work we describe a lithographic technique for fabrication of Fresnel lenses. This technique is achieved using a photo mask and Norland Optical Adhesive No. 65. The main characteristics of this lens are his low cost and its flexibility due to the material. Some experimental results are shown.
M. Ortiz-Gutierrez, M. A. Salgado-Verduzco, A. Olivares-Perez, J. L. Juarez-Perez, M. Perez-Cortes, J. C. Ibarra-Torres, J. Castro-Ramos   +6 more
openaire   +1 more source

Ultralight inflatable fresnel lens solar concentrators

AIP Conference Proceedings, 1998
Since 1986, ENTECH and NASA Lewis have been developing refractive solar concentrators for space applications. These Fresnel lens concentrators can be configured as either point-focus dome lenses or line-focus cylindrical lenses. Small point-focus or line-focus lenses can be used to concentrate sunlight onto solar cells in space photovoltaic (PV) arrays.
Mark J. O’Neill, Michael F. Piszczor
openaire   +1 more source

Color-corrected Fresnel lens for solar concentration

Optics Letters, 1980
A new linear convex Fresnel lens with its groove side down is described. The design philosophy is similar to that of the highly concentrating two-focal Fresnel lens but includes a correction for chromatic aberration. A solar-concentration ratio as high as 80 is achieved. For wide-acceptance angles, the concentration nears the theoretical maximum.
openaire   +2 more sources