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Sample records for light-weight fresnel lenses

  1. Laminated Fresnel lenses

    SciTech Connect

    Jebens, R.W.

    1980-04-01

    A fabrication method for making plastic-on-glass laminated Fresnel lenses is discussed. These Fresnel lenses are for application in an RCA solar photovoltaic concentrator array now in the prototype stage of development. This laminated Fresnel lens fabrication method consists of making a Dow Corning J RTV silastic rubber mold of a master lens array. This mold is used to vacuum cast only the lens facets onto a low-iron tempered-glass substrate with an epoxy resin such as Hysol 0S 1000, a bisphenol-A resin with a flexibilizer that is anhydride cured. Cast acrylic Fresnel lens arrays commercialy available have potential cleaning and abrasion problems, have very large thermal expansion, and have dimensional uncertainties in their manufacture. The laminated lens is dimensionally stable with low thermal expansion, has good cleaning characteristics, and is very inexpensive in materials cost. The measured transmission of such a lens on low-iron glass is 80.4% compared with 85.1% for a cast acrylic lens, and the optical quality is good enough for application in the 100X to 200X concentration range. An approach to making large lens arrays (3 by 6 ft) on a commercial scale is explored.

  2. Fresnel lenses for ultrasonic inspection

    NASA Technical Reports Server (NTRS)

    Kammerer, C. C.

    1980-01-01

    Ultrasonic Fresnel lenses are effective focusing elements with potential applications in ultrasonic "contact" testing for defects in materials. Ultrasonic beams focused on concave lenses are used successfully with immersion transducers, for which test object is immersed in water bath. However, for large objects, objects that are already installed, objects on production lines, and objects that can be damaged by water, contact testing is more practical than immersion.

  3. Fresnel's Lighthouse Lenses

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2007-01-01

    One of the rewards of walking up the scores of steps winding around the inside of the shaft of a lighthouse is turning inward and examining the glass optical system. This arrangement of prisms, lenses, and reflectors is used to project the light from a relatively small source in a beam that can be seen far at sea.

  4. Fresnel's Lighthouse Lenses

    NASA Astrophysics Data System (ADS)

    Greenslade, Thomas B.

    2007-12-01

    One of the rewards of walking up the scores of steps winding around the inside of the shaft of a lighthouse is turning inward and examining the glass optical system. This arrangement of prisms, lenses, and reflectors is used to project the light from a relatively small source in a beam that can be seen far at sea.

  5. Light diffraction by concentrator Fresnel lenses.

    PubMed

    Hornung, Thorsten; Nitz, Peter

    2014-05-05

    Fresnel lenses are widely used in concentrating photovoltaic (CPV) systems as primary optical elements focusing sunlight onto small solar cells or onto entrance apertures of secondary optical elements attached to the solar cells. Calculations using the Young-Maggi-Rubinowicz theory of diffraction yield analytical expressions for the amount of light spilling outside these target areas due to diffraction at the edges of the concentrator Fresnel lenses. Explicit equations are given for the diffraction loss due to planar Fresnel lenses with small prisms and due to arbitrarily shaped Fresnel lenses. Furthermore, the cases of illumination by monochromatic, polychromatic, totally spatially coherent and partially spatially coherent light (e.g. from the solar disc) are treated, resulting in analytical formulae. Examples using realistic values show losses due to diffraction of up to several percent.

  6. Design principles for Fresnel lenses in telecentric applications

    NASA Astrophysics Data System (ADS)

    McCall, Brian; Claytor, Nelson

    2016-09-01

    Fresnel lenses have been found by some optical systems designers to be useful in combination with a main lens to provide quality telecentric images. Aspheric Fresnel lenses are an ideal choice for this application because they achieve a high degree of telecentricity across the entire field of view and introduce very little distortion. In a telecentric system consisting of an aspheric Fresnel lens and an off the shelf non-telecentric main lens, the design parameters are few. Aberration theory, constraints on the visibility of the grooves, and physical constraints can effectively be used to quickly determine if a solution exists for a given application and identify the solution space if it does.

  7. Fresnel Lenses for Wide-Aperture Optical Receivers

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid

    2004-01-01

    Wide-aperture receivers for freespace optical communication systems would utilize Fresnel lenses instead of conventional telescope lenses, according to a proposal. Fresnel lenses weigh and cost much less than conventional lenses having equal aperture widths. Plastic Fresnel lenses are commercially available in diameters up to 5 m large enough to satisfy requirements for aperture widths of the order of meters for collecting sufficient light in typical long-distance free-space optical communication systems. Fresnel lenses are not yet suitable for high-quality diffraction-limited imaging, especially in polychromatic light. However, optical communication systems utilize monochromatic light, and there is no requirement for high-quality imaging; instead, the basic requirement for an optical receiver is to collect the incoming monochromatic light over a wide aperture and concentrate the light onto a photodetector. Because of lens aberrations and diffraction, the light passing through any lens is focused to a blur circle rather than to a point. Calculations for some representative cases of wide-aperture non-diffraction-limited Fresnel lenses have shown that it should be possible to attain blur-circle diameters of less than 2 mm. Preferably, the blur-circle diameter should match the width of the photodetector. For most high-bandwidth communication applications, the required photodetector diameters would be about 1 mm. In a less-preferable case in which the blur circle was wider than a single photodetector, it would be possible to occupy the blur circle with an array of photodetectors. As an alternative to using a single large Fresnel lens, one could use an array of somewhat smaller lenses to synthesize the equivalent aperture area. Such a configuration might be preferable in a case in which a single Fresnel lens of the requisite large size would be impractical to manufacture, and the blur circle could not be made small enough. For example one could construct a square array

  8. Compatibility of Fresnel lenses and photovoltaic cells in concentrator modules

    SciTech Connect

    Stillwell, C.B.; Shafer, B.D.

    1981-01-01

    Test data are used to compare, for point focus photovoltaic concentrator modules, the relationship between Fresnel lens and module efficiency. The data shows that lenses designed for maximum optical efficiency may not produce the maximum module efficiency. Lenses designed with consideration for the photon flux distribution on the solar cell may improve module efficiency possibly at some loss in lens optical performance.

  9. Solar Photovoltaic Array With Mini-Dome Fresnel Lenses

    NASA Technical Reports Server (NTRS)

    Piszczor, Michael F., Jr.; O'Neill, Mark J.

    1994-01-01

    Mini-dome Fresnel lenses concentrate sunlight onto individual photovoltaic cells. Facets of Fresnel lens designed to refract incident light at angle of minimum deviation to minimize reflective losses. Prismatic cover on surface of each cell reduces losses by redirecting incident light away from metal contacts toward bulk of semiconductor, where it is usefully absorbed. Simple design of mini-dome concentrator array easily adaptable to automated manufacturing techniques currently used by semiconductor industry. Attractive option for variety of future space missions.

  10. Optical loss due to diffraction by concentrator Fresnel lenses

    SciTech Connect

    Hornung, Thorsten Nitz, Peter

    2014-09-26

    Fresnel lenses are widely used in concentrating photovoltaic (CPV) systems as a primary optical element. They focus sunlight on small solar cells or on the entrance apertures of secondary optical elements. A Fresnel lens consists of several prism rings and diffraction by these prism rings is unavoidable. Some of the light that would reach a designated target area according to geometric optics will miss it due to diffraction. This diffraction loss may be of relevant magnitude for CPV applications. The results of published analytical calculations are evaluated, discussed, and compared to computer simulations and measurements.

  11. Microfabrication of SU-8 Fresnel lenses for THz imaging

    NASA Astrophysics Data System (ADS)

    Hajji, M.; Pan, Y.; Hammler, J.; Zeze, D.; Balocco, C.; Gallant, A. J.

    2016-02-01

    Free space focusing of terahertz light is normally achieved through the use of bulky parabolic mirrors. Alternatively, for focusing onto a substrate or sample, polished high resistivity silicon lenses are commonly used. This paper presents the design, fabrication and testing of an alternative approach, based on Fresnel microlenses which have been optimised for use in the terahertz region. The microlenses are fabricated using layers of SU-8 photoresist and conventional UV photolithography. The lens design approach presented here provides a low cost, mass production ready alternative to silicon lenses. Fresnel lenses can have a large numerical aperture and a short focal length and are well suited for use in terahertz imaging systems. The focal point of the demonstrated Fresnel microlens has been calculated to be approximately 5 mm at 1 THz using a commercial FDTD solver, Lumerical. Characterization of the microlenses by VNA (Vector Network Analyzer) operating in the frequency range of 750 GHz to 1.1 THz is presented and discussed. The measured focal length using the VNA approach corresponds well to the values calculated using the FDTD solver and demonstrates effective focusing from highly compact lenses.

  12. Aberrations in Fresnel Lenses and Mirrors

    NASA Technical Reports Server (NTRS)

    Gregory, Don

    1999-01-01

    The NASA/MSFC Shooting Star program revealed a number of technical problems that must be solved before solar thermal propulsion can become a reality. The fundamental problem of interest here is the collection of solar energy. This is the first step in the propulsion process and indeed the most important. Everything else depends on the efficiency and focusing ability of the collection lens or mirror. An initial model of Fresnel lens behavior using a wave optics approach has been completed and the results were encouraging enough to warrant an experimental investigation. This experimental investigation confirmed some of the effects predicted and produced invaluable photographic evidence of coherence based diffraction and aberration.

  13. Fresnel lenses based on dye-doped liquid crystals

    NASA Astrophysics Data System (ADS)

    Lin, Liang-Chen; Cheng, Ko-Ting; Liu, Cheng-Kai; Ting, Chi-Lun; Jau, Hung-Chang; Lin, Tsung-Hsien; Fuh, Andy Y.

    2008-02-01

    We demonstrated transmissive- and reflective-type Fresnel lenses based on dye-doped liquid crystal using photoalignment technique. The former is a polarization-independent and electrically tunable. The maximum diffraction efficiency reaches 37%, which approaches the theoretical limit ~ 41 %. Such a lens functions as a half-wave plate, and this feature could be well preserved under the applied voltage. The reflective-type Fresnel lens is based on dye-doped cholesteric liquid crystals (DDCLC). The formed lens persists without any external disturbance, and its focusing efficiency, analyzed using circularly polarized light, is ~ 23.7 %, which almost equals the measured diffraction efficiency of the used Fresnel-zone-plate mask (~ 25.6 %). The lens is thermally erasable, and rewritable. Notably, both of the transmissive- and reflective-type Fresnel lenses are switchable between focusing and defocusing states, upon application of a voltage. In addition, these devices are simple to fabricate, and have fast switching responses between focusing and defocusing state.

  14. Chromatic aberration effect on solar energy systems using Fresnel lenses

    SciTech Connect

    Lorenzo, E.

    1981-11-01

    In concentration systems using Fresnel lenses the effect of the chromatic aberration can become important. In this paper we propose a method to take this effect into account for designing purposes. Also we define a parameter that allows one to estimate the degradation of the thermodynamic quality of the concentrator due to this effect. This parameter follows a hyperbolic law, with the acceptance angle showing that it is important to consider chromatic aberration when modeling concentrators with a high concentration factor. However, this complexity is unnecessary for moderate or low concentration factors.

  15. Solar concentration by curved-base Fresnel lenses

    NASA Technical Reports Server (NTRS)

    Cosby, R. M.

    1977-01-01

    The solar concentration performance of idealized curved base line focusing Fresnel lenses is analyzed. A simple optical model was introduced to study the effects of base curvature and lens f-number. Thin lens ray tracing and the laws of reflection and refraction are used to develop expression for lens transmittance and image plane intensity profiles. The intensity distribution over the solar spectrum, lens dispersion effects, and absorption by the lens material are included in the analysis. Model capabilities include assessment of lens performance in the presence of small transverse tracking errors and the sensitivity of solar image characteristics to focusing.

  16. Design and development of injection molded Fresnel lenses for point-focus photovoltaic systems

    SciTech Connect

    Grendol, C.L.

    1987-05-01

    A summary of work performed on a method of injection molding an 80% efficient point-focus Fresnel lens is presented. A current optical design for compression molded lenses yields a 68.5% efficiency when translated directly to injection molding. An optical design optimized for injection molding, with a mold and process developed for high efficiency Fresnel lenses, yields an 82% efficiency.

  17. Fresnel lenses. (Latest citations from the US Patent Bibliographic file with exemplary claims). NewSearch

    SciTech Connect

    Not Available

    1994-10-01

    The bibliography contains citations of selected patents concerning the design and implementation of Fresnel lenses. Citations focus on manufacturing methods and designs for specific applications. Fresnel lenses used in overhead projectors, solar concentrators, and infrared motion detectors are also described. (Contains a minimum of 71 citations and includes a subject term index and title list.)

  18. Static Linear Fresnel Lenses as LCPV System in a Greenhouse

    NASA Astrophysics Data System (ADS)

    Sonneveld, P. J.; Swinkels, G. L. A. M.; van Tuijl, B. A. J.; Janssen, H. J. J.; de Zwart, H. F.

    2011-12-01

    A low concentrating PV system with water cooling (LCPVT system) will result in electrical and thermal energy output from the solar energy excess entering a building or greenhouse. All the direct radiation could be converted, which corresponds to 75% of the incoming solar energy. This will significantly reduce the demand of cooling of the building. For an optimal performance it is beneficial to construct asymmetric roof elements with a steep inclination at the north side (the exact angle of course depends on the latitude of the building site). The Fresnel lens structure is oriented in upwards direction. In the current design, two of them are placed between an AR-coated double glass structure to prevent pollution and condensation on the lenses. Compared with a previous system, the number of lenses is reduced from 3 to 2 lenses, which reduces the costs of the system by limiting the number of receivers. By the upward facing of the lens structure, the focus quality is preserved over a much broader range of angles of incidence compared to a lens with downward facing structures. Each PMMA lens with a size of 1.20 m×1.60 m is composed of 12 `tiles' for easy production. The focal distance of the lens is 1,875 m and the concentration factor 50x. In most cases the focus line is thinner than 3 cm and the transmission is above 80%. The performance of these lenses with respect of the shape of the focal area and the position of the focal line has been analyzed with ray tracing techniques. From this analyses it was concluded that tracking of the receiver module is possible with two motors. One motor controls the distance between lens and receiver and one motor controls the translocation of the receivers parallel to the lens. The second conclusion was that the positions of the focal line are within the bounds of the greenhouse construction for almost the whole year. Only in winter, the focal line will be unreachable from time to time. A 480 m2 greenhouse with the LCPVT system

  19. Development of Large-Aperture, Light-Weight Fresnel Lenses for Gossamer Space Telescopes

    SciTech Connect

    Sham, D; Hyde, R; Weisberg, A; Early, J; Rushford, M; Britten, J

    2002-04-29

    In order to examine more distant astronomical objects, with higher resolution, future space telescopes require objectives with significantly larger aperture than presently available. NASA has identified a progression in size from the 2.4m aperture objective currently used in the HUBBLE space telescope[l,2], to 25m and greater in order to observe, e.g., extra-solar planets. Since weight is a crucial factor for any object sent into space, the relative weight of large optics over a given area must be reduced[3]. The areal mass density of the primary mirror for the Hubble space telescope is {approx}200 kg/m{sup 2}. This is expected to be reduced to around 15 kg/m{sup 2} for the successor to Hubble--the next generation space telescope (NGST)[4]. For future very large aperture telescopes needed for extra-solar planet detection, the areal mass density must be reduced even further. For example, the areal mass density goal for the Gossamer space telescopes is < 1 kg/m{sup 2}. The production of lightweight focusing optics at >10m size is also an enabling technology for many other applications such as Earth observation, power beaming, and optical communications.

  20. Antireflective coatings on Fresnel lenses by spin-coating of solid silica nanoparticles.

    PubMed

    Zhou, Gang; He, Junhui

    2013-08-01

    Antireflective (AR) coatings were fabricated from solid silica nanoparticles (SNPs) of ca. 16 nm in size on Fresnel lenses via one-step spin coating without any high temperature treatment. Transmission electron microscopy was used to observe the morphology and structure of the SNPs. Transmission spectra were recorded on a UV-vis-NIR spectrophotometer. The results indicated that Fresnel lenses covered with the SNPs coatings were much more transparent than the uncoated Fresnel lens. The maximum transmittance of the coated Fresnel lenses reached as high as 99.8%, whereas that of the uncoated Fresnel lens is only 94.3%. Surface wettability was studied by a contact angle/interface system, and the results indicated that the coatings on Fresnel lenses were more hydrophilic than the uncoated Fresnel lens. The surface morphologies and structures of the coatings were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The mechanical robustness of the coatings was examined by pencil scratch tests and attenuated total reflection infrared spectroscopy (ATR-IR).

  1. Technology of Manufacture of the Negative Matrices for Linear Fresnel Lenses

    NASA Astrophysics Data System (ADS)

    Lapshin, V. V.; Zakharevich, E. M.; Grubyy, S. V.

    2016-04-01

    This article describes the main structural features of negative matrices which are intended for the production of positive copies of linear Fresnel lenses. Linear lenses are used in a space solar energy industry as solar concentrators in the photovoltaic modules. The article covers the essential requirements which are placed on the equipment and technology for the production of such matrices.

  2. Design and fabrication of Si-HDPE hybrid Fresnel lenses for infrared imaging systems.

    PubMed

    Manaf, Ahmad Rosli Abdul; Sugiyama, Tsunetoshi; Yan, Jiwang

    2017-01-23

    In this work, novel hybrid Fresnel lenses for infrared (IR) optical applications were designed and fabricated. The Fresnel structures were replicated from an ultraprecision diamond-turned aluminum mold to an extremely thin layer (tens of microns) of high-density polyethylene polymer, which was directly bonded onto a flat single-crystal silicon wafer by press molding without using adhesives. Night mode imaging results showed that the fabricated lenses were able to visualize objects in dark fields with acceptable image quality. The capability of the lenses for thermography imaging was also demonstrated. This research provides a cost-effective method for fabricating ultrathin IR optical components.

  3. Future X-Ray Telescopes: Fresnel Lenses and Interferometry

    NASA Astrophysics Data System (ADS)

    Smith, T. L.; Romaine, S. E.

    2002-12-01

    Science goals are well established for the next generation X-ray observatories, such as Constellation-X1 and Xeus2, which are being planned as followups to the successful Chandra3 and XMM-Newton4, missions which were launched in 1999. Both Constellation-X and Xeus observatories, planned for launch the end of this decade, emphasize large collecting area and high spectral resolution over angular resolution. Hence their angular resolution will not equal the < ~0.5'' of Chandra, the highest angular resolution of any X-ray observatory to date. These missions indicate a new direction for future X-ray observatories: from large general purpose observatories, such as Chandra, to missions with more focused science goals and therefore more tailored designs. Just as Constellation-X and Xeus emphasize throughput and spectral resolution, there are other designs which emphasize imaging with angular resolution surpassing Chandra's already invaluable 0.5''. This will be the emphasis of the missions to follow Constellation-X5. Two of these designs, Fresnel Lenses and X-ray interferometry, present optical systems which, theoretically, can reach micro-arcsecond angular resolutions. Many obstacles have stood in the way of making these designs a reality, but technology is now being developed6 which overcomes these obstacles, opening the door to X-ray imaging at unprecedented resolution. We present basic characteristics of both optical designs as well as the type of science that would benefit most from a milliarcsecond (or better) observatory. 1http://constellation.gsfc.nasa.gov/ 2http://astro.estec.esa.nl/SA-general/Projects/XEUS/ 3http://chandra.harvard.edu/ 4http://sci.esa.int/home/xmm-newton/index.cfm 5http://maxim.gsfc.nasa.gov/ 6Cash, W., Shipley, A., Osterman, S., & Joy, M. 2000, Nature 407, 160 This work was supported in part by NSF grant AST-9731923 to the SAO Summer Intern program.

  4. Diffraction Limited Performance of Infra Red Fresnel Lenses.

    DTIC Science & Technology

    The effect of diffraction on Fresnel lens performance has been calculated. It is shown that the bandwidth of a coherent lens is very narrow. For low...monochromatic (laser) applications, on the other hand, the Fresnel lens may offer significant cost advantages over the conventional alternatives.

  5. Collection and concentration of solar energy using Fresnel type lenses

    NASA Technical Reports Server (NTRS)

    Wilson, R. F.

    1975-01-01

    The efficiency of collecting solar energy using a Fresnel type lens was measured for two different collectors. A flow collector utilizes the temperature difference and heat capacity in water measurements to determine the amount of absorbed energy retained from sun rays passing through the Fresnel lens. A static collector is a hollow copper box filled with vegetable heating oil for absorption of focused solar radiation.

  6. Integration of Defocus by Dual Power Fresnel Lenses Inhibits Myopia in the Mammalian Eye

    PubMed Central

    McFadden, Sally A.; Tse, Dennis Y.; Bowrey, Hannah E.; Leotta, Amelia J.; Lam, Carly S.; Wildsoet, Christine F.; To, Chi-Ho

    2014-01-01

    Purpose. Eye growth compensates in opposite directions to single vision (SV) negative and positive lenses. We evaluated the response of the guinea pig eye to Fresnel-type lenses incorporating two different powers. Methods. A total of 114 guinea pigs (10 groups with 9–14 in each) wore a lens over one eye and interocular differences in refractive error and ocular dimensions were measured in each of three experiments. First, the effects of three Fresnel designs with various diopter (D) combinations (−5D/0D; +5D/0D or −5D/+5D dual power) were compared to three SV lenses (−5D, +5D, or 0D). Second, the ratio of −5D and +5D power in a Fresnel lens was varied (50:50 compared with 60:40). Third, myopia was induced by 4 days of exposure to a SV −5D lens, which was then exchanged for a Fresnel lens (−5D/+5D) or one of two SV lenses (+5D or −5D) and ocular parameters tracked for a further 3 weeks. Results. Dual power lenses induced an intermediate response between that to the two constituent powers (lenses +5D, +5D/0D, 0D, −5D/+5D, −5D/0D and −5D induced +2.1 D, +0.7 D, +0.1 D, −0.3 D, −1.6 D and −5.1 D in mean intraocular differences in refractive error, respectively), and changing the ratio of powers induced responses equal to their weighted average. In already myopic animals, continued treatment with SV negative lenses increased their myopia (from −3.3 D to −4.2 D), while switching to SV positive lenses or −5D/+5D Fresnel lenses reduced their myopia (by 2.9 D and 2.3 D, respectively). Conclusions. The mammalian eye integrates competing defocus to guide its refractive development and eye growth. Fresnel lenses, incorporating positive or plano power with negative power, can slow ocular growth, suggesting that such designs may control myopia progression in humans. PMID:24398103

  7. A New Technique Producing Double-Sided Spherical Fresnel Lens Segments Assembled to Large Aperture Lenses

    NASA Astrophysics Data System (ADS)

    Ohmori, H.; Takahashi, Y.; Shimizu, H.; Uehara, Y.; Suzuki, T.; Ueno, Y.; Hillman, L. W.; Zuccaro, A.; EUSO Collaboration

    2003-07-01

    A new technique of molding of lens segments has been developed to produce a large, double-sided, curved Fresnel lenses for refractive telescopes. The molding process involves two steps of spherically curved plate formation and lens gro ove transfer onto the curved plate. These molding process have been carried out with two sides of the diamond-cut dies set in the hydraulic press machine at elevated temperatures to the lens material that is a transparent UV-acrylic of Mitsubishi. Ultra-precision dies were made of oxygen-free copp er, which were cut by diamond to ols to make Fresnel facets. A four-axis ultra-precision cutting machine has been developed first to manufacture ultra-precision mold dies. Double-sided, curved Fresnel lens segments will be used as circumference petals of lenses of 2500mm aperture surrounding a 1500mm diameter central lens.

  8. Optical Design and Manufacturing of Fresnel Lenses for The First Korean High Concentration Solar PV System

    NASA Astrophysics Data System (ADS)

    Ryu, Kwangsun; Shin, Goo-Hwan; Cha, Wonho; Kang, Seongwon; Kim, Youngsik; Kang, Gi-Hwan

    2011-12-01

    In this study, we designed and optimized flat Fresnel lens and the light pipe to develop 500X concentrated solar PV system. In the process, we compare the transmission efficiencies according to groove types. We performed rigorous ray tracing simulation of the flat Fresnel lenses. The computer aided simulation showed the `grooves in' case has the better efficiency than that of `grooves out' case. Based on the ray-trace results, we designed and manufactured sample Fresnel lenses. The optical performance were measured and compared with ray-trace results. Finally, the optical efficiency was measured to be above 75%. All the design and manufacturing were performed based on that InGaP/InGaAs/Ge triple junction solar cell is used to convert the photon energy to electrical power. Field test will be made and analyzed in the near future.

  9. Multilayer Anti-Reflective Coating Development for PMMA Fresnel Lenses

    DTIC Science & Technology

    2010-06-07

    been sputter deposited on UV transparent polymethylmethacrylate (UVT-PMMA) windows. The amorphous coatings are deposited using reactive sputtering in a...SUBJECT TERMS Anti-reflective coatings, Fresnel lens, polymethylmethacrylate , PMMA 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18...high quality dielectric materials deposited on a variety of substrates including polymethylmethacrylate (PMMA)  Highly amorphous films achieved

  10. A new generation of multilayer Bragg-Fresnel lenses

    SciTech Connect

    Erko, A.; Firsov, A.; Yakshin, A.; Chevallier, P.; Dhez, P.

    1995-12-31

    A new type of Bragg-Fresnel multilayer lens (BFML) have been fabricated at IMT RAS and tested at LURE. The idea to combine different diffraction orders of a zone plate in one focal spot introduced by Simpson and Michette has been realized in a BFML with extended aperture. Matching of the two diffraction orders, the first and third, into one focal plane increases the output flux by a factor of two and the spatial resolution in the same order of magnitude.

  11. Side-pumping Nd:YAG solar laser by six Fresnel lenses

    NASA Astrophysics Data System (ADS)

    Tomás, G.; Liang, D.; Almeida, J.

    2013-11-01

    To obtain a good compromise between collection efficiency and brightness figure of merit of solar-pumped lasers, a new side-pumping scheme is proposed. Firstly the solar radiations are collected and concentrated by six 700 mm diameter Fresnel lenses. The concentrated solar radiations are subsequently reflected by six plane folding mirrors with 95% reflectivity, into a common focal spot. This allows the concentration of 1740 W solar power with about 6.4 W/mm2 peak solar flux. A secondary concentrator is composed of six aspheric fused silica lenses, positioned around a 40 mm radius fused silica sphere, compressing all the concentrated solar radiation from the six Fresnel lenses into an 8 mm diameter by 9 mm length Nd:YAG single-crystal rod. By positioning the spherical concentrator slightly above the aspherical lenses, a more uniform absorption profile is achieved. Mechanical support with a water cooling system ensures an efficient cooling to the laser medium. Optimal laser parameters are found through ZEMAX™ and LASCAD™ numerical analysis software. Only 16% of the solar power is absorbed by Nd:YAG medium. Solar laser power of 42.6 W is numerically calculated, reaching a collection efficiency of 18.5 W/m2. For a 400 mm plane-concave resonance cavity with -5m radius of curvature, M2 x = M2 y = 22 beam quality factors are numerically predicted. A near uniform pump absorption profile can be achieved by increasing the number of Fresnel lens and folding mirrors.

  12. Fabrication of high-efficiency Fresnel-type lenses by pinhole diffraction imaging of sol-gel hybrid materials

    SciTech Connect

    Kang, Dong Jun; Phong, Phan Viet; Bae, Byeong-Soo

    2004-11-08

    Sol-gel hybrid materials containing a large quantity of photoactive molecules exhibited large changes in both refractive index and volume on UV exposure. The materials were used for fabrication of Fresnel-type lenses using a simple method: pinhole diffraction imaging. With this technique, problems associated with the contact method could be overcome and Fresnel-type lenses with good focusing performance could be fabricated easily. Importantly, a high diffraction efficiency approaching 85% could be obtained.

  13. Solar concentration properties of flat fresnel lenses with large F-numbers

    NASA Technical Reports Server (NTRS)

    Cosby, R. M.

    1978-01-01

    The solar concentration performances of flat, line-focusing sun-tracking Fresnel lenses with selected f-numbers between 0.9 and 2.0 were analyzed. Lens transmittance was found to have a weak dependence on f-number, with a 2% increase occuring as the f-number is increased from 0.9 to 2.0. The geometric concentration ratio for perfectly tracking lenses peaked for an f-number near 1.35. Intensity profiles were more uniform over the image extent for large f-number lenses when compared to the f/0.9 lens results. Substantial decreases in geometri concentration ratios were observed for transverse tracking errors equal to or below 1 degree for all f-number lenses. With respect to tracking errors, the solar performance is optimum for f-numbers between 1.25 and 1.5.

  14. Design methodology accounting for fabrication errors in manufactured modified Fresnel lenses for controlled LED illumination.

    PubMed

    Shim, Jongmyeong; Kim, Joongeok; Lee, Jinhyung; Park, Changsu; Cho, Eikhyun; Kang, Shinill

    2015-07-27

    The increasing demand for lightweight, miniaturized electronic devices has prompted the development of small, high-performance optical components for light-emitting diode (LED) illumination. As such, the Fresnel lens is widely used in applications due to its compact configuration. However, the vertical groove angle between the optical axis and the groove inner facets in a conventional Fresnel lens creates an inherent Fresnel loss, which degrades optical performance. Modified Fresnel lenses (MFLs) have been proposed in which the groove angles along the optical paths are carefully controlled; however, in practice, the optical performance of MFLs is inferior to the theoretical performance due to fabrication errors, as conventional design methods do not account for fabrication errors as part of the design process. In this study, the Fresnel loss and the loss area due to microscopic fabrication errors in the MFL were theoretically derived to determine optical performance. Based on this analysis, a design method for the MFL accounting for the fabrication errors was proposed. MFLs were fabricated using an ultraviolet imprinting process and an injection molding process, two representative processes with differing fabrication errors. The MFL fabrication error associated with each process was examined analytically and experimentally to investigate our methodology.

  15. Optical computed tomography utilizing a rotating mirror and Fresnel lenses: operating principles and preliminary results

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Wuu, Cheng-Shie

    2013-02-01

    The performance of a fast optical computed tomography (CT) scanner based on a point laser source, a small area photodiode detector, and two optical-grade Fresnel lenses is evaluated. The OCTOPUS™-10× optical CT scanner (MGS Research Inc., Madison, CT) is an upgrade of the OCTOPUS™ research scanner with improved design for faster motion of the laser beam and faster data acquisition process. The motion of the laser beam in the new configuration is driven by the rotational motion of a scanning mirror. The center of the scanning mirror and the center of the photodiode detector are adjusted to be on the focal points of two coaxial Fresnel lenses. A glass water tank is placed between the two Fresnel lenses to house gel phantoms and matching liquids. The laser beam scans over the water tank in parallel beam geometry for projection data as the scanning mirror rotates at a frequency faster than 0.1 s per circle. Signal sampling is performed independently of the motion of the scanning mirror, to reduce the processing time for the synchronization of the stepper motors and the data acquisition board. An in-house developed reference image normalization mechanism is added to the image reconstruction program to correct the non-uniform light transmitting property of the Fresnel lenses. Technical issues with regard to the new design of the scanner are addressed, including projection data extraction from raw data samples, non-uniform pixel averaging and reference image normalization. To evaluate the dosimetric accuracy of the scanner, the reconstructed images from a 16 MeV, 6 cm × 6 cm electron field irradiation were compared with those from the Eclipse treatment planning system (Varian Corporation, Palo Alto, CA). The spatial resolution of the scanner is demonstrated to be of sub-millimeter accuracy. The effectiveness of the reference normalization method for correcting the non-uniform light transmitting property of the Fresnel lenses is analyzed. A sub-millimeter accuracy of

  16. Thin Fresnel zone plate lenses for focusing underwater sound

    NASA Astrophysics Data System (ADS)

    Calvo, David C.; Thangawng, Abel L.; Nicholas, Michael; Layman, Christopher N.

    2015-07-01

    A Fresnel zone plate (FZP) lens of the Soret type creates a focus by constructive interference of waves diffracted through open annular zones in an opaque screen. For underwater sound below MHz frequencies, a large FZP that blocks sound using high-impedance, dense materials would have practical disadvantages. We experimentally and numerically investigate an alternative approach of creating a FZP with thin (0.4λ) acoustically opaque zones made of soft silicone rubber foam attached to a thin (0.1λ) transparent rubber substrate. An ultra-thin (0.0068λ) FZP that achieves higher gain is also proposed and simulated which uses low-volume fraction, bubble-like resonant air ring cavities to construct opaque zones. Laboratory measurements at 200 kHz indicate that the rubber foam can be accurately modeled as a lossy fluid with an acoustic impedance approximately 1/10 that of water. Measured focal gains up to 20 dB agree with theoretical predictions for normal and oblique incidence. The measured focal radius of 0.68λ (peak-to-null) agrees with the Rayleigh diffraction limit prediction of 0.61 λ/NA (NA = 0.88) for a low-aberration lens.

  17. Thin Fresnel zone plate lenses for focusing underwater sound

    SciTech Connect

    Calvo, David C. Thangawng, Abel L.; Nicholas, Michael; Layman, Christopher N.

    2015-07-06

    A Fresnel zone plate (FZP) lens of the Soret type creates a focus by constructive interference of waves diffracted through open annular zones in an opaque screen. For underwater sound below MHz frequencies, a large FZP that blocks sound using high-impedance, dense materials would have practical disadvantages. We experimentally and numerically investigate an alternative approach of creating a FZP with thin (0.4λ) acoustically opaque zones made of soft silicone rubber foam attached to a thin (0.1λ) transparent rubber substrate. An ultra-thin (0.0068λ) FZP that achieves higher gain is also proposed and simulated which uses low-volume fraction, bubble-like resonant air ring cavities to construct opaque zones. Laboratory measurements at 200 kHz indicate that the rubber foam can be accurately modeled as a lossy fluid with an acoustic impedance approximately 1/10 that of water. Measured focal gains up to 20 dB agree with theoretical predictions for normal and oblique incidence. The measured focal radius of 0.68λ (peak-to-null) agrees with the Rayleigh diffraction limit prediction of 0.61 λ/NA (NA = 0.88) for a low-aberration lens.

  18. Temperature Dependent Measurement And Simulation Of Fresnel Lenses For Concentrating Photovoltaics

    NASA Astrophysics Data System (ADS)

    Hornung, Thorsten; Bachmaier, Andreas; Nitz, Peter; Gombert, Andreas

    2010-10-01

    Concentrating photovoltaics (CPV) require large areas of optical components that concentrate incident sunlight effectively onto a solar cell. Fresnel lenses are often used as primary optical component providing this concentration. When applied in the field, varying conditions during operation lead to variations in lens temperature which has a strong impact on the optical efficiency of the lenses. A setup for indoor characterization with the ability to heat lens plates allows for the assessment of the quality of Fresnel lenses by means of their irradiance profiles in the focal plane. To analyze the measured temperature dependency we simulate thermal deformations of the lens geometry with finite element method (FEM) tools and use the resulting lens geometry as an input to ray tracing simulations. We performed high accuracy measurements of the temperature and wavelength dependent refractive indices of relevant lens materials to obtain additional input data for computer simulations. A close match between computer simulations and measurements of the irradiance in the focal plane could be achieved, validating our simulation approach. This allows us to judge and optimize the temperature dependence of new lens designs before building and testing prototypes. The simulations themselves allow us to analyze and understand all superimposed effects in detail. The developed tools in combination with detailed solar resource data and knowledge of the CPV system will be the basis for future assessment of overall performance and further optimization of optics for CPV applications.

  19. Temperature and wavelength dependent measurement and simulation of Fresnel lenses for concentrating photovoltaics

    NASA Astrophysics Data System (ADS)

    Hornung, Thorsten; Bachmaier, Andreas; Nitz, Peter; Gombert, Andreas

    2010-05-01

    Fresnel lenses are often used as primary optical components in concentrating photovoltaics (CPV). When applied in the field, varying conditions during operation lead to variations in lens temperature which has a strong impact on the optical efficiency of the lenses. A setup for indoor characterization with the ability to heat lens plates allows for the assessment of the quality of Fresnel lenses by means of their irradiance profiles in the focal plane. To analyze the measured temperature dependency we simulate thermal deformations of the lens geometry with finite element method (FEM) tools and use the resulting lens geometry as an input to ray tracing simulations. A close match between computer simulations and measurements of the irradiance profile in the focal plane is achieved, validating our simulation approach. This allows us to judge and optimize the temperature dependence of new lens designs before building and testing prototypes. The simulation enables us to analyze and understand all superimposed effects in detail. The developed tools in combination with detailed solar resource data and knowledge of the CPV system will be the basis for future assessment of overall performance and further optimization of optics for CPV applications.

  20. Core-doped Nd:YAG disk solar laser uniformly pumped by six Fresnel lenses

    NASA Astrophysics Data System (ADS)

    Garcia, D.; Liang, D.; Almeida, J.

    2013-11-01

    A novel solar laser uniformly pumped by six Fresnel lenses is proposed here. The incident solar radiation is firstly collected and concentrated by six 0.8 m diameter Fresnel lenses and then reflected by other six plane mirrors to a central focal zone, where a laser head is mounted. About 2.5 kW solar power with 3.5 W/mm2 peak solar flux can be achieved in the focal zone. The laser head is composed of a fused silica six-sphere type secondary concentrator that further compresses the concentrated solar power from the six Fresnel lenses-plane mirrors to a core-doped YAG Nd3+:YAG ceramic disk. Optimum pumping parameters and solar laser output powers are found through ZEMAX non-sequential ray-tracing and LASCAD laser cavity analysis, respectively. The laser resonant cavity is formed by a PR 1064 nm output coupler and a HR 1064 nm plane reflector. An 8 mm diameter central hole is drilled through the six-sphere type concentrator to allow the extraction of laser power from the disk. Since only 16 % of the useful solar power is absorbed by the Nd:YAG medium, for 950 W/m2 of terrestrial solar irradiation, the effective solar pump power of 456 W is assumed in ray-tracing analysis. 72.2 W of multimode laser power is predicted for an 8 mm diameter gain medium embedded within a conical undoped YAG cladding, reaching the collection efficiency of 24.1 W/m2. M2 = 16.6 is numerically calculated, corresponding to the brightness figure of merit of 0.26 W. A near uniform absorbed pump profile is achieved.

  1. Space Photovoltaic Concentrator Using Robust Fresnel Lenses, 4-Junction Cells, Graphene Radiators, and Articulating Receivers

    NASA Technical Reports Server (NTRS)

    O'Neill, Mark; McDanal, A. J.; Brandhorst, Henry; Spence, Brian; Iqbal, Shawn; Sharps, Paul; McPheeters, Clay; Steinfeldt, Jeff; Piszczor, Michael; Myers, Matt

    2016-01-01

    At the 42nd PVSC, our team presented recent advances in our space photovoltaic concentrator technology. These advances include more robust Fresnel lenses for optical concentration, more thermally conductive graphene radiators for waste heat rejection, improved color-mixing lens technology to minimize chromatic aberration losses with 4-junction solar cells, and an articulating photovoltaic receiver enabling single-axis sun-tracking, while maintaining a sharp focal line despite large beta angles of incidence. In the past year, under a NASA Phase II SBIR program, our team has made much additional progress in the development of this new space photovoltaic concentrator technology, as described in this paper.

  2. Optical computed tomography utilizing a rotating mirror and Fresnel lenses: operating principles and preliminary results.

    PubMed

    Xu, Y; Wuu, Cheng-Shie

    2013-02-07

    The performance of a fast optical computed tomography (CT) scanner based on a point laser source, a small area photodiode detector, and two optical-grade Fresnel lenses is evaluated. The OCTOPUS™-10× optical CT scanner (MGS Research Inc., Madison, CT) is an upgrade of the OCTOPUS™ research scanner with improved design for faster motion of the laser beam and faster data acquisition process. The motion of the laser beam in the new configuration is driven by the rotational motion of a scanning mirror. The center of the scanning mirror and the center of the photodiode detector are adjusted to be on the focal points of two coaxial Fresnel lenses. A glass water tank is placed between the two Fresnel lenses to house gel phantoms and matching liquids. The laser beam scans over the water tank in parallel beam geometry for projection data as the scanning mirror rotates at a frequency faster than 0.1 s per circle. Signal sampling is performed independently of the motion of the scanning mirror, to reduce the processing time for the synchronization of the stepper motors and the data acquisition board. An in-house developed reference image normalization mechanism is added to the image reconstruction program to correct the non-uniform light transmitting property of the Fresnel lenses. Technical issues with regard to the new design of the scanner are addressed, including projection data extraction from raw data samples, non-uniform pixel averaging and reference image normalization. To evaluate the dosimetric accuracy of the scanner, the reconstructed images from a 16 MeV, 6 cm × 6 cm electron field irradiation were compared with those from the Eclipse treatment planning system (Varian Corporation, Palo Alto, CA). The spatial resolution of the scanner is demonstrated to be of sub-millimeter accuracy. The effectiveness of the reference normalization method for correcting the non-uniform light transmitting property of the Fresnel lenses is analyzed. A sub

  3. End-side-pumped Nd:YAG solar laser with four Fresnel lenses

    NASA Astrophysics Data System (ADS)

    Galinhas, B.; Liang, D.

    2013-11-01

    Solar-pumped solid-state lasers are promising for renewable extreme-temperature material processing and space power applications. An efficient Fresnel lens solar laser pumping approach is proposed here. The incoming solar power is firstly collected and concentrated by four 800 mm x 800 mm square Fresnel lenses and redirected by four plane mirrors to a central focal spot of 12 mm FWHM diameter, attaining 443 W concentrated solar power. Secondly for further concentration, both a set of four aspherical lenses and a fused silica sphere are positioned in the focal zone. Both side-pumping and end-pumping are achieved simultaneously for a 7 mm diameter by 12 mm length Nd:YAG single-crystal rod mounted within the sphere. Since there is no strong pump radiation absorption within the central core zone of the rod, thermal lensing effect is also minimized with the proposed scheme. A 600 mm length plane-plane resonant cavity is used to extract 1064 nm laser emission efficiently. Optimum pumping parameters and solar laser output powers are found through ZEMAX non-sequential ray-tracing and LASCAD laser cavity analysis. By taking into account 16 % of spectrum overlap between the 1.0 % Nd:YAG absorption spectrum and the solar spectrum, 183 W absorbed solar power is assumed in ZEMAX numerical analysis. Considering a round trip loss of 1.32 % for the resonant cavity, 45.2 W laser power is numerically attained through LASCAD software, corresponding to 17.7 W/m2 collection efficiency. The proposed pumping scheme presents an excellent compromise between the laser output power and its beam quality.

  4. Design and imaging performance of achromatic diffractive-refractive x-ray and gamma-ray Fresnel lenses.

    PubMed

    Skinner, Gerald K

    2004-09-01

    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, is investigated, and the trade-off between resolution and useful bandwidth in different circumstances is discussed. Provided that the focal ratio is large, correction lenses made from low atomic number materials can be used with x rays in the range of approximately 10-100 keV without stepping. The use of stepping extends the possibility of correction to higher-aperture systems, to energies as low as a few kilo electron volts, and to gamma rays of mega electron volt energy.

  5. Fresnel Lens

    NASA Technical Reports Server (NTRS)

    Watson, Michael D.; Scott, Steve; Lamb, David; Zimmerman, Joe E. (Technical Monitor)

    2001-01-01

    Fresnel lenses span the full range of sizes from lens a few micrometers in diameter to lens several meters in diameter. These lenses are utilized in various fields including optical communication, theatrical lighting, office equipment, video entertainment systems, solar concentrators, and scientific research instruments. These lenses function either as diffractive or refractive optical elements depending on the geometrical feature size of the lens. The basic functions of these lenses is described followed by an overview of fabrication methods. A summary of applications is then provided illustrating the rich variety of applications for which fresnel lenses may be designed to fulfill.

  6. Optical-CT 3D Dosimetry Using Fresnel Lenses with Minimal Refractive-Index Matching Fluid

    PubMed Central

    Bache, Steven; Malcolm, Javian; Adamovics, John; Oldham, Mark

    2016-01-01

    Telecentric optical computed tomography (optical-CT) is a state-of-the-art method for visualizing and quantifying 3-dimensional dose distributions in radiochromic dosimeters. In this work a prototype telecentric system (DFOS—Duke Fresnel Optical-CT Scanner) is evaluated which incorporates two substantial design changes: the use of Fresnel lenses (reducing lens costs from $10-30K t0 $1-3K) and the use of a ‘solid tank’ (which reduces noise, and the volume of refractively matched fluid from 1ltr to 10cc). The efficacy of DFOS was evaluated by direct comparison against commissioned scanners in our lab. Measured dose distributions from all systems were compared against the predicted dose distributions from a commissioned treatment planning system (TPS). Three treatment plans were investigated including a simple four-field box treatment, a multiple small field delivery, and a complex IMRT treatment. Dosimeters were imaged within 2h post irradiation, using consistent scanning techniques (360 projections acquired at 1 degree intervals, reconstruction at 2mm). DFOS efficacy was evaluated through inspection of dose line-profiles, and 2D and 3D dose and gamma maps. DFOS/TPS gamma pass rates with 3%/3mm dose difference/distance-to-agreement criteria ranged from 89.3% to 92.2%, compared to from 95.6% to 99.0% obtained with the commissioned system. The 3D gamma pass rate between the commissioned system and DFOS was 98.2%. The typical noise rates in DFOS reconstructions were up to 3%, compared to under 2% for the commissioned system. In conclusion, while the introduction of a solid tank proved advantageous with regards to cost and convenience, further work is required to improve the image quality and dose reconstruction accuracy of the new DFOS optical-CT system. PMID:27019460

  7. Optical-CT 3D Dosimetry Using Fresnel Lenses with Minimal Refractive-Index Matching Fluid.

    PubMed

    Bache, Steven; Malcolm, Javian; Adamovics, John; Oldham, Mark

    2016-01-01

    Telecentric optical computed tomography (optical-CT) is a state-of-the-art method for visualizing and quantifying 3-dimensional dose distributions in radiochromic dosimeters. In this work a prototype telecentric system (DFOS-Duke Fresnel Optical-CT Scanner) is evaluated which incorporates two substantial design changes: the use of Fresnel lenses (reducing lens costs from $10-30K t0 $1-3K) and the use of a 'solid tank' (which reduces noise, and the volume of refractively matched fluid from 1 ltr to 10 cc). The efficacy of DFOS was evaluated by direct comparison against commissioned scanners in our lab. Measured dose distributions from all systems were compared against the predicted dose distributions from a commissioned treatment planning system (TPS). Three treatment plans were investigated including a simple four-field box treatment, a multiple small field delivery, and a complex IMRT treatment. Dosimeters were imaged within 2 h post irradiation, using consistent scanning techniques (360 projections acquired at 1 degree intervals, reconstruction at 2mm). DFOS efficacy was evaluated through inspection of dose line-profiles, and 2D and 3D dose and gamma maps. DFOS/TPS gamma pass rates with 3%/3mm dose difference/distance-to-agreement criteria ranged from 89.3% to 92.2%, compared to from 95.6% to 99.0% obtained with the commissioned system. The 3D gamma pass rate between the commissioned system and DFOS was 98.2%. The typical noise rates in DFOS reconstructions were up to 3%, compared to under 2% for the commissioned system. In conclusion, while the introduction of a solid tank proved advantageous with regards to cost and convenience, further work is required to improve the image quality and dose reconstruction accuracy of the new DFOS optical-CT system.

  8. An Experimental Study on the Effect of Using Fresnel Lenses on the Performance of Solar Stills

    NASA Astrophysics Data System (ADS)

    Abdelsalam, Tarek I.; Abdel-Mesih, Bahy

    The global water concern is mainly about the scarcity of fresh water resources despite the abundance of saline and brackish water in oceans, seas, and underground. Solar desalination offers a worthy solution to produce fresh water by using solar radiation, which also lessens the energy concern by offering a renewable source of energy to alter the consumption of fossil fuels and other non-renewable resources. One of the solar desalination technologies is the solar still system, which is a portable unit capable of producing distilled water by evaporating brackish or saline water by using solar thermal energy. The steam is then condensed on the inside of the glass cover and collected as fresh water. Solar stills are easy to manufacture and install using local materials and workmanship, which suits underprivileged remote communities that face difficulties in finding clean potable water, while locating near a source of saline water. However, efficiency and productivity of solar stills are still feeble when compared to other traditional desalination techniques. As an attempt to overcome these issues, an upgraded system is proposed and tested experimentally to augment the incoming solar radiation falling on the top glass surface of the still by concentrating extra solar radiation to preheat the flowing feedwater to the solar still system. The results of the experimental study showed that the integration of linear Fresnel lenses has approximately tripled the productivity of distilled water and improved efficiency of a solar still, by about 68.76 %, when compared to a conventional non-concentrating solar still.

  9. Electrically switchable Fresnel lenses in polymer-stabilized ferroelectric liquid crystals

    NASA Astrophysics Data System (ADS)

    Yeh, Hui-Chen; Ke, Ming-Wei; Liu, Yu-Mei

    2017-01-01

    In this study, we demonstrate the fabrication of an electrically switchable Fresnel lens based on surface-stabilized ferroelectric liquid crystals (SSFLCs) with polymer networks. The Fresnel lens was fabricated by injecting a monomer-doped ferroelectric liquid crystal into an extremely thin cell and exposing the cell to ultraviolet light through a Fresnel-zone-plate mask. The fabricated Fresnel lens consisted of the SSFLC and polymer-stabilized SSFLC structures. The focusing effect can be switched on by applying an appropriate voltage, and the characteristics of FLCs enable a rapid response on the order of milliseconds.

  10. Polarization-independent and high-diffraction-efficiency Fresnel lenses based on blue phase liquid crystals.

    PubMed

    Lin, Chi-Huang; Wang, Yu-Yin; Hsieh, Cheng-Wei

    2011-02-15

    A polarization-independent and high-diffraction-efficiency Fresnel lens is developed based on blue phase liquid crystals (BPLCs). The optically isotropic characteristic of BPLCs is used to produce a polarization-independent Fresnel lens. The small optical phase shift of BPLCs that is induced by the Kerr effect is sufficient for the BPLC Fresnel lens to have high theoretical and experimental diffraction efficiencies of 41% and ∼34%, respectively. An electrically erasable memory effect in the focusing diffraction at an electric field E>4.44 V/μm is observed. The electro-optical properties of the BPLC Fresnel lens are analyzed and discussed.

  11. The distance temperature map as method to analyze the optical properties of Fresnel lenses and their interaction with multi-junction solar cells

    NASA Astrophysics Data System (ADS)

    Hornung, Thorsten; Kiefel, Peter; Nitz, Peter

    2015-09-01

    The optical efficiency of Fresnel lens based solar concentrators varies with the temperature of the Fresnel lens. The dependency of any quantity of interest (e.g. optical efficiency) on Fresnel lens temperature can be visualized by 2d color plots that simultaneously show it as a function of the distance between solar cell and Fresnel lens and as a function of Fresnel lens temperature. This visualization, which is called DTmap, strongly facilitates the analysis of the thermal behavior of a Fresnel lens and the optimization of module height. Based on DTmaps we reveal and discuss serveral details of the thermal behavior of silicone on glass (SOG) Fresnel lenses. In addition, the DTmap is shown for the efficiency of a system consisting of a Fresnel lens and a lattice matched three-junction and a four-junction solar cell. The results demonstrate that the interaction of the concentrator optics and the solar cell is not trivial and may also be studied using DTmaps.

  12. Multi-Fresnel lenses pumping approach for improving high-power Nd:YAG solar laser beam quality.

    PubMed

    Liang, Dawei; Almeida, Joana

    2013-07-20

    To significantly improve the present-day high-power solar laser beam quality, a three-stage multi-Fresnel lenses approach is proposed for side-pumping either a Nd:YAG single-crystal or a core-doped Sm(3+)Nd:YAG ceramic rod. Optimum pumping and laser beam parameters are found through ZEMAX and LASCAD numerical analysis. The proposed scheme offers a uniform absorption profile along the rod. 167 W laser power can be achieved, corresponding to 29.3 W/m(2) collection efficiency. High brightness figure of merit of 8.34 W is expected for the core-doped rod within a convex-concave resonator, which is 1300 times higher than that of the most-recent high-power solar laser.

  13. Comparison of Fresnel lenses and parabolic mirrors as solar energy concentrators

    SciTech Connect

    Lorenzo, E.; Luque, A.

    1982-05-15

    This paper compares the gain that can be achieved with a one- or two-stage concentrator, when the first stage is a Fresnel lens or a parabolic mirror, as a function of the luminosity of the concentrator. The results show that the achievable gain using a parabolic mirror is greater than that obtained using a flat or roof lens but is lower than that obtained using a curved lens.

  14. Comparison of Fresnel lenses and parabolic mirrors as solar energy concentrators.

    PubMed

    Lorenzo, E; Luque, A

    1982-05-15

    This paper compares the gain that can be achieved with a one- or two-stage concentrator, when the first stage is a Fresnel lens or a parabolic mirror, as a function of the luminosity of the concentrator. The results show that the achievable gain using a parabolic mirror is greater than that obtained using a flat or roof lens but is lower than that obtained using a curved lens.

  15. A CPV System with Static Linear Fresnel Lenses in a Greenhouse

    NASA Astrophysics Data System (ADS)

    Sonneveld, Piet; Zahn, Helmut; Swinkels, Gert-Jan

    2010-10-01

    A new CPV system with a static linear Fresnel lens, silicon PV module suitable for concentrated radiation and an innovative tracking system is integrated in a greenhouse covering. The basic idea of this horticultural application is to develop a greenhouse for pot plants (typical shadow plants) which don't like high direct radiation. Removing all direct radiation will block up to 77% of the solar energy, which will reduce the necessary cooling capacity. The solar energy focused on the Thermal Photovoltaic (PV/T) module generates electric and thermal energy. The PV/T module is tracked in the focal line and requires cooling due to the high heat load of the concentrated radiation (concentration factor of 50 times). All parts are integrated in a greenhouse with a size of about 36 m2. The electrical and thermal yield is determined for Dutch climate circumstances. Some measurements were performed with a PMMA linear Fresnel lens between double glass. Further improvement of the performance of the CPV-system is possible by using a PDMS lens directly laminated on glass and using AR-coated glass. This lens is developed with ZEMAX and the results of the Ray-tracing simulations are presented with the lens structure oriented in an upwards and downwards position. The best performance of the static linear Fresnel lens is achieved with upwards orientation of the lens structures. In practice this is only possible with the Fresnel lens placed between a double glass structure, which will keep the lens clean and free of water.

  16. Light-weight plastination.

    PubMed

    Steinke, Hanno; Rabi, Suganthy; Saito, Toshiyuki; Sawutti, Alimjan; Miyaki, Takayoshi; Itoh, Masahiro; Spanel-Borowski, Katharina

    2008-11-20

    Plastination is an excellent technique which helps to keep the anatomical specimens in a dry, odourless state. Since the invention of plastination technique by von Hagens, research has been done to improve the quality of plastinated specimens. In this paper, we have described a method of producing light-weight plastinated specimens using xylene along with silicone and in the final step, substitute xylene with air. The finished plastinated specimens were light-weight, dry, odourless and robust. This method requires less use of resin thus making the plastination technique more cost-effective. The light-weight specimens are easy to carry and can easily be used for teaching.

  17. Fresnel lens light applicator

    SciTech Connect

    Castel, J.C.; Kerwin, R.G.

    1987-09-01

    A therapeutic laser radiation applicator is described which consists of: means for providing laser radiation in an elliptical transverse distribution; and means for converting the elliptical transverse distribution of the laser radiation into a circular distribution thereof comprising at least two axially spaced fresnel lenses, and means for mounting the fresnel lenses in preselected association with the laser radiation means for refracting a portion of a laser radiation to the circular distribution adapted to provide a therapeutic tissue irradiation pattern.

  18. Performance comparison of four kinds of flat nonimaging Fresnel lenses made of polycarbonates and polymethyl methacrylate for concentrated photovoltaics

    NASA Astrophysics Data System (ADS)

    Languy, Fabian; Habraken, Serge

    2011-07-01

    Solar concentrators made of a single refractive primary optics are limited to a concentration ratio of about 1000× [Opt. Express19, A280 (2011)], due only to longitudinal chromatic aberration, while mirrors are limited to ˜46,000× by the angular size of the Sun. To reduce the chromatic aberration while keeping cost-effective systems for concentrated photovoltaics, a study of four different kinds of flat Fresnel doublets made of polycarbonates and polymethyl methacrylate is presented. It reveals that Fresnel doublets may have fewer optical losses than non-Fresnel doublets, with a lower lateral chromatic split allowing for even higher concentration ratio.

  19. Large aperture Fresnel telescopes/011

    SciTech Connect

    Hyde, R.A., LLNL

    1998-07-16

    At Livermore we`ve spent the last two years examining an alternative approach towards very large aperture (VLA) telescopes, one based upon transmissive Fresnel lenses rather than on mirrors. Fresnel lenses are attractive for VLA telescopes because they are launchable (lightweight, packagable, and deployable) and because they virtually eliminate the traditional, very tight, surface shape requirements faced by reflecting telescopes. Their (potentially severe) optical drawback, a very narrow spectral bandwidth, can be eliminated by use of a second (much smaller) chromatically-correcting Fresnel element. This enables Fresnel VLA telescopes to provide either single band ({Delta}{lambda}/{lambda} {approximately} 0.1), multiple band, or continuous spectral coverage. Building and fielding such large Fresnel lenses will present a significant challenge, but one which appears, with effort, to be solvable.

  20. Large-aperture fast multilevel Fresnel zone lenses in glass and ultrathin polymer films for visible and near-infrared imaging applications.

    PubMed

    Britten, Jerald A; Dixit, Shamusundar N; DeBruyckere, Michael; Steadfast, Daniel; Hackett, James; Farmer, Brandon; Poe, Garrett; Patrick, Brian; Atcheson, Paul D; Domber, Jeanette L; Seltzer, Aaron

    2014-04-10

    The ability to fabricate 4-level diffractive structures with 1 µm critical dimensions has been demonstrated for the creation of fast (∼f/3.1 at 633 nm) Fresnel zone lenses (FZLs) with >60% diffraction efficiency into the -1 focusing order and nearly complete suppression of 0 and +1 orders. This is done using tooling capable of producing optics with 800 mm apertures. A 4-level grating fabricated in glass at 300 mm aperture is shown to have <15  nm rms holographic phase error. Glass FZLs have also been used as mandrels for casting zero-thermal-expansion, 20 µm thick polymer films created with the 4-level structure as a route to mass replication of efficient diffractive membranes for ultralight segmented space-based telescope applications.

  1. Characterization and correction of spherical aberration due to glass substrate in the design and fabrication of Fresnel zone lenses.

    PubMed

    Vijayakumar, A; Bhattacharya, S

    2013-08-20

    As with a conventional lens, a Fresnel zone lens (FZL) can be used to image objects at infinity or nearby. In the latter case, the FZL converts a diverging spherical wavefront into a converging spherical wavefront. The glass substrate on which the FZL is fabricated introduces spherical aberration resulting in a shift of the image plane and blurring of the image. Two novel schemes for correction of this spherical aberration are proposed and studied in this paper. To demonstrate them, FZLs are designed with and without aberration correction. They are fabricated using electron beam direct writing. The devices are evaluated and the accuracy of the proposed aberration correction schemes is validated.

  2. Linear Fresnel lens with polar tracking.

    PubMed

    Kritchman, E M

    1981-04-01

    The performance of coma and color corrected linear Fresnel lenses for solar concentration is evaluated for use in polar tracking systems. Effective concentrations of up to 90 at 75% efficiency were obtained.

  3. Linear Fresnel lens with polar tracking

    SciTech Connect

    Kritchman, E.M.

    1981-04-01

    The performance of coma and color corrected linear Fresnel lenses for solar concentration is evaluated for use in polar tracking systems. Effective concentrations of up to 90 at 75% efficiency were obtained.

  4. Light-weight ceramic insulation

    NASA Technical Reports Server (NTRS)

    Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

    2002-01-01

    Ultra-high temperature, light-weight, ceramic insulation such as ceramic tile is obtained by pyrolyzing a siloxane gel derived from the reaction of at least one organo dialkoxy silane and at least one tetralkoxy silane in an acid or base liquid medium. The reaction mixture of the tetra- and dialkoxy silanes may contain also an effective amount of a mono- or trialkoxy silane to obtain the siloxane gel. The siloxane gel is dried at ambient pressures to form a siloxane ceramic precursor without significant shrinkage. The siloxane ceramic precursor is subsequently pyrolyzed, in an inert atmosphere, to form the black ceramic insulation comprising atoms of silicon, carbon and oxygen. The ceramic insulation, can be characterized as a porous, uniform ceramic tile resistant to oxidation at temperatures ranging as high as 1700.degree. C. and is particularly useful as lightweight tiles for spacecraft and other high-temperature insulation applications.

  5. Scaling laws for light-weight optics

    NASA Technical Reports Server (NTRS)

    Valente, Tina M.

    1990-01-01

    Scaling laws for light-weight optical systems are examined. A cubic relationship between mirror diameter and weight has been suggested and used by many designers of optical systems as the best description for all light-weight mirrors. A survey of existing light-weight systems in the open literature has been made to clarify this issue. Fifty existing optical systems were surveyed with all varieties of light-weight mirrors including glass and beryllium structured mirrors, contoured mirrors, and very thin solid mirrors. These mirrors were then categorized and weight to diameter ratio was plotted to find a best fit curve for each case. A best fitting curve program tests nineteen different equations and ranks a 'goodness of fit' for each of these equations. The resulting relationship found for each light-weight mirror category helps to quantify light-weight optical systems and methods of fabrication and provides comparisons between mirror types.

  6. The Light-Weight Group Library

    SciTech Connect

    Moody, A. T.

    2012-07-02

    The Light-Weight Group (LWGRP) bibrary provides data structures and collective routines to define and operate on groups of MPI processes. Groups can be created and freed efficiently in O(log N) time space requiring less overhead that constructing full MPI communicators. This facilitates faster development of applications and libraries that need to rapidly create, use, and destroy process groups.

  7. Light Weight Silicon Mirrors for Space Instrumentation

    NASA Technical Reports Server (NTRS)

    Bly, Vincent T.; Hill, Peter C.; Hagopian, John G.; Strojay, Carl R.; Miller, Timothy

    2012-01-01

    Each mirror is a monolithic structure from a single crystal of silicon. The mirrors are light weighted after the optical surface is ground and polished. Mirrors made during the initial phase of this work were typically 1/50 lambda or better (RMS at 633 n m)

  8. Terahertz Brewster lenses.

    PubMed

    Wichmann, Matthias; Scherger, Benedikt; Schumann, Steffen; Lippert, Sina; Scheller, Maik; Busch, Stefan F; Jansen, Christian; Koch, Martin

    2011-12-05

    Typical lenses suffer from Fresnel reflections at their surfaces, reducing the transmitted power and leading to interference phenomena. While antireflection coatings can efficiently suppress these reflections for a small frequency window, broadband antireflection coatings remain challenging. In this paper, we report on the simulation and experimental investigation of Brewster lenses in the THz-range. These lenses can be operated under the Brewster angle, ensuring reflection-free transmission of p-polarized light in an extremely broad spectral range. Experimental proof of the excellent focusing capabilities of the Brewster lenses is given by frequency and spatially resolved focus plane measurements using a fiber-coupled THz-TDS system.

  9. Fresnel lens on new photosensitive material

    NASA Astrophysics Data System (ADS)

    Ortiz-Gutierrez, M.; Salgado-Verduzco, M. A.; Olivares-Perez, A.; Juarez-Perez, J. L.; Perez-Cortes, M.; Ibarra-Torres, J. C.; Castro-Ramos, J.

    2005-04-01

    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.

  10. Optimising efficiency in diamond turned Fresnel mould masters

    NASA Astrophysics Data System (ADS)

    Allsop, John L.; Mateboer, Arjen; Shore, Paul

    2011-05-01

    Radial and Linear Fresnel Lenses are finding application as light concentrators for Concentrated Photovoltaic and Concentrated Solar Thermal power applications. The efficiency of these diffractive lenses directly affects the yield of such systems. Peaks and valleys of the optical facets of the Fresnel lens must be sharp in order to prevent diffusion and transmission loss due to rounding. For diamond turned mould masters, optical facet tip sharpness is affected by machining accuracy, tool-path and tool wear/mileage. Strategies to optimise optical facet tip sharpness are presented which enable production of large lenses with minimal degradation of optical quality. Radial Fresnel produced with diameters over 500mm and Linear Fresnel over 1m long are discussed with data on structure fidelity and tool wear.

  11. Light-weight analyzer for odor recognition

    DOEpatents

    Vass, Arpad A; Wise, Marcus B

    2014-05-20

    The invention provides a light weight analyzer, e.g., detector, capable of locating clandestine graves. The detector utilizes the very specific and unique chemicals identified in the database of human decompositional odor. This detector, based on specific chemical compounds found relevant to human decomposition, is the next step forward in clandestine grave detection and will take the guess-work out of current methods using canines and ground-penetrating radar, which have historically been unreliable. The detector is self contained, portable and built for field use. Both visual and auditory cues are provided to the operator.

  12. Stretchable Binary Fresnel Lens for Focus Tuning

    NASA Astrophysics Data System (ADS)

    Li, Xueming; Wei, Lei; Poelma, René H.; Vollebregt, Sten; Wei, Jia; Urbach, Hendrik Paul; Sarro, Pasqualina M.; Zhang, Guo Qi

    2016-05-01

    This paper presents a tuneable binary amplitude Fresnel lens produced by wafer-level microfabrication. The Fresnel lens is fabricated by encapsulating lithographically defined vertically aligned carbon nanotube (CNT) bundles inside a polydimethyl-siloxane (PDMS) layer. The composite lens material combines the excellent optical absorption properties of the CNT with the transparency and stretchability of the PDMS. By stretching the elastomeric composite in radial direction, the lens focal length is tuned. Good focusing response is demonstrated and a large focus change (≥24%) was achieved by stretching lenses up to 11.4%.

  13. Stretchable Binary Fresnel Lens for Focus Tuning.

    PubMed

    Li, Xueming; Wei, Lei; Poelma, René H; Vollebregt, Sten; Wei, Jia; Urbach, Hendrik Paul; Sarro, Pasqualina M; Zhang, Guo Qi

    2016-05-03

    This paper presents a tuneable binary amplitude Fresnel lens produced by wafer-level microfabrication. The Fresnel lens is fabricated by encapsulating lithographically defined vertically aligned carbon nanotube (CNT) bundles inside a polydimethyl-siloxane (PDMS) layer. The composite lens material combines the excellent optical absorption properties of the CNT with the transparency and stretchability of the PDMS. By stretching the elastomeric composite in radial direction, the lens focal length is tuned. Good focusing response is demonstrated and a large focus change (≥24%) was achieved by stretching lenses up to 11.4%.

  14. Stretchable Binary Fresnel Lens for Focus Tuning

    PubMed Central

    Li, Xueming; Wei, Lei; Poelma, René H.; Vollebregt, Sten; Wei, Jia; Urbach, Hendrik Paul; Sarro, Pasqualina M.; Zhang, Guo Qi

    2016-01-01

    This paper presents a tuneable binary amplitude Fresnel lens produced by wafer-level microfabrication. The Fresnel lens is fabricated by encapsulating lithographically defined vertically aligned carbon nanotube (CNT) bundles inside a polydimethyl-siloxane (PDMS) layer. The composite lens material combines the excellent optical absorption properties of the CNT with the transparency and stretchability of the PDMS. By stretching the elastomeric composite in radial direction, the lens focal length is tuned. Good focusing response is demonstrated and a large focus change (≥24%) was achieved by stretching lenses up to 11.4%. PMID:27139747

  15. Scaling laws for light weight optics, studies of light weight mirrors mounting and dynamic mirror stress, and light weight mirror and mount designs

    NASA Technical Reports Server (NTRS)

    Vukobratovich, Daniel; Richard, Ralph M.; Valente, Tina M.; Cho, Myung K.

    1990-01-01

    Scaling laws for light-weight optical systems are examined. A cubic relationship between mirror diameter and weight has been suggested and used by many designers of optical systems as the best description for all light-weight mirrors. A survey of existing light-weight systems in the open literature was made to clarify this issue. Fifty existing optical systems were surveyed with all varieties of light-weight mirrors including glass and beryllium structured mirrors, contoured mirrors, and very thin solid mirrors. These mirrors were then categorized and weight to diameter ratio was plotted to find a best curve for each case. A best fitting curve program tests nineteen different equations and ranks a goodness-to-fit for each of these equations. The resulting relationship found for each light-weight mirror category helps to quantify light-weight optical systems and methods of fabrication and provides comparisons between mirror types.

  16. Fresnel Lens Sidewall Design for Imaging Optics

    NASA Astrophysics Data System (ADS)

    Fujii, T.; Goulet, A.; Hattori, K.; Konno, K.; Tanaka, A.; Bosmans, R.; Sawada, M.; Yazawa, H.

    2015-03-01

    We developed a ray tracing simulation tool for imaging systems including a Fresnel lens with a quasi-arbitrary sidewall structure. One issue with Fresnel lens is that noise in the image plane can appear from rays passing through or reflected at its sidewalls. One way to reduce it is to modify the orientation of the sidewalls so that rays will not reach the image plane. To find the best sidewall orientations, we developed a method where locally, a sidewall can freely be oriented. We could then derive the best modulation scheme for each Fresnel lens sidewall. In the case of a single imaging Fresnel lens, relative parasite noise intensity could mostly be prevented. To experimentally check our method, snapshot images were taken with single Fresnel lenses and a single spherical lens. No noticeable differences in image quality could be observed using a standard C-MOS camera. However, parasite noise could experimentally be detected with a Fresnel lens prototype when using a very! high-dynamic range C-MOS camera.

  17. Light weight high-stiffness stage platen

    DOEpatents

    Spence, Paul A.

    2001-01-01

    An improved light weight, stiff stage platen for photolithography is provided. The high stiffness of the stage platen is exemplified by a relatively high first resonant vibrational mode as determined, for instance, by finite element modal analysis. The stage platen can be employed to support a chuck that is designed to secure a mask or wafer. The stage platen includes a frame that has interior walls that define an interior region and that has exterior walls wherein the outer surfaces of at least two adjacent walls are reflective mirror surfaces; and a matrix of ribs within the interior region that is connected to the interior walls wherein the stage platen exhibits a first vibrational mode at a frequency of greater than about 1000 Hz.

  18. Names in Physics: Fresnel

    ERIC Educational Resources Information Center

    Cooper, M. L.

    1970-01-01

    This short biography of Fresnel traces his early education, his work as an engineer and his theories and discoveries in optics. The importance of Fresnel's ideas on diffraction, interference and double refraction are discussed. Bibliography. (LC)

  19. Light-weight black ceramic insulation

    NASA Technical Reports Server (NTRS)

    Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

    2003-01-01

    Ultra-high temperature, light-weight, black ceramic insulation having a density ranging from about 0.12 g/cc. to 0.6 g/cc. such as ceramic tile is obtained by pyrolyzing siloxane gels derived from the reaction of at least one organo dialkoxy silane and at least one tetralkoxy silane in an acid or base liquid medium. The reaction mixture of the tetra- and dialkoxy silanes also may contain an effective amount of a mono- or trialkoxy silane to obtain the siloxane gels. The siloxane gels are dried at ambient temperatures and pressures to form siloxane ceramic precursors without significant shrinkage. The siloxane ceramic precursors are subsequently pyrolyzed, in an inert atmosphere, to form the black ceramic insulation comprising atoms of silicon, carbon and oxygen. The ceramic insulation can be characterized as a porous, uniform ceramic tile resistant to oxidation at temperatures ranging as high as 1700.degree. C., and particularly useful as lightweight tiles for spacecraft and other high-temperature insulation applications.

  20. Design and development of a laminated Fresnel lens for point focus pv systems

    SciTech Connect

    Hobbs, R.B. Jr.

    1981-01-01

    The design and fabrication of a laminated Fresnel lens for point focus photovoltaic concentrators systems is described. The lens consists of a glass superstrate to which a thin 6.7 inch square Fresnel lens is bonded. A key aim of the program was to investigate the technical feasibility of injection molding acceptable quality Fresnel lenses. Significant progress was made in demonstrating this feasibility and is reported.

  1. Feasibility of Thin Fresnel Lens Use in Multi-kj, Short Pulse Laser Systems

    SciTech Connect

    Jovanovic, I; Dixit, S N; Wattellier, B; Hermann, M R; Barty, C P J

    2002-11-18

    Recently-developed, thin-Fresnel-lens technology offers the potential for transmissive focusing of high-peak-power, ultrashort-duration laser pulses. Calculations of the transverse and longitudinal spectral blurring effects of thin Fresnel lenses when used to focus ultrashort, high-energy laser pulses are presented.

  2. Electrically controlled polarization-independent liquid-crystal Fresnel lens arrays.

    PubMed

    Patel, J S; Rastani, K

    1991-04-01

    We describe the properties and construction of a polarization-independent Fresnel lens array using nematic liquid crystals in which the diffraction efficiency of lenses can be electrically controlled. A novel structure is used such that the principal axis of the liquid crystals in two adjacent zones of each Fresnel lens are orthogonal. This makes the device polarization independent. We have characterized these lenses at different applied fields and input polarizations by diffracting an argon-ion beam into focus.

  3. Optical Docking Aid Containing Fresnel Lenses

    NASA Technical Reports Server (NTRS)

    Pierce, Cole J.

    1995-01-01

    Proposed device provides self-contained visual cues to aid in docking. Similar to devices used to guide pilots in landing on aircraft carriers. Positions and directions of beams of light give observer visual cues of position relative to docking target point. Optical assemblies generate directed, diverging beams of light that, together, mark approach path to docking point. Conceived for use in docking spacecraft at Space Station Freedom, device adapted to numerous industrial docking and alignment applications.

  4. Ultralight inflatable fresnel lens solar concentrators

    NASA Astrophysics Data System (ADS)

    O'Neill, Mark J.; Piszczor, Michael F.

    1998-01-01

    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. Large point-focus lenses can be used for high solar flux applications. In March 1997, a NASA Phase I SBIR program was initiated to develop ultralight inflatable lenses of both the line-focus and point-focus types. Special program emphasis is being placed on large point-focus lenses for various high-concentration applications, including solar dynamic (SD) power, alkali metal thermal energy conversion (AMTEC), thermophotovoltaics (TPV), and solar thermal propulsion (STP). Key outputs of the Phase I program include conceptual designs, optical performance predictions, micrometeoroid puncture analyses, manufacturing process identification, and functional prototype hardware. This paper summarizes the key results of the Phase I program, leading to the conclusion that inflatable dome lenses will provide excellent high-concentration optical performance, unequaled shape error tolerance, extremely low mass/aperture area ratio, proven manufacturability with space qualified materials, and small make-up gas requirements to maintain inflation on-orbit.

  5. Fabrication of micro-array of Fresnel rings on Si by electron beam lithography and reactive ion etching

    NASA Astrophysics Data System (ADS)

    Chiromawa, Nura Liman; Ibrahim, Kamarulazizi

    2016-02-01

    Recently, micro-lenses have attracted more attention among optoelectronics device application developers. This paper presents the micro-array of Si-Fresnel rings fabricated by the electron beam lithography and reactive ion etching. Fresnel rings units containing 11 concentric rings were created on the PMMA layer with the outermost Fresnel ring, having an external diameter of 45.24 μm, and are located ≈200 μm away from each other. These structures can be copied as the micro-array of Fresnel lenses for optoelectronics device applications.

  6. Automated Fresnel lens tester system

    SciTech Connect

    Phipps, G.S.

    1981-07-01

    An automated data collection system controlled by a desktop computer has been developed for testing Fresnel concentrators (lenses) intended for solar energy applications. The system maps the two-dimensional irradiance pattern (image) formed in a plane parallel to the lens, whereas the lens and detector assembly track the sun. A point detector silicon diode (0.5-mm-dia active area) measures the irradiance at each point of an operator-defined rectilinear grid of data positions. Comparison with a second detector measuring solar insolation levels results in solar concentration ratios over the image plane. Summation of image plane energies allows calculation of lens efficiencies for various solar cell sizes. Various graphical plots of concentration ratio data help to visualize energy distribution patterns.

  7. Inflatable lenses for space photovoltaic concentrator arrays

    SciTech Connect

    O`Neill, M.J.; Piszczor, M.F.

    1997-12-31

    For 12 years, ENTECH and NASA Lewis have been developing Fresnel lens concentrator technology for space power applications. ENTECH provided the point-focus mini-dome lenses for the PASP+ array, launched in 1994. These silicone lenses performed well on orbit, with only about 3% optical performance loss after 1 year in elliptical orbit, with high radiation, atomic oxygen, and ultraviolet exposure. The only protection for these silicone lenses was a thin-film coating provided by OCLI. ENTECH also provided the line-focus lenses for the SCARLET 1 and SCARLET 2 arrays in 1995 and 1997, respectively. These lenses are laminated assemblies, with protective ceria glass superstrates over the silicone lens. In March 1997, ENTECH and NASA Lewis began development of inflatable Fresnel lenses, to achieve lower weight, smaller launch volume, reduced cost, less fragility, and other advantages. This paper summarizes the new concentrator approach, including key program results to date.

  8. 21 CFR 886.1390 - Flexible diagnostic Fresnel lens.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1390 Flexible diagnostic Fresnel lens... to the back of the spectacle lenses of patients with aphakia (absence of the lens of the eye). (b... from the current good manufacturing practice requirements of the quality system regulation in part...

  9. 21 CFR 886.1655 - Ophthalmic Fresnel prism.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ophthalmic Fresnel prism. 886.1655 Section 886.1655 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... provides the optical effect of a prism. The device is intended to be applied to spectacle lenses to give...

  10. 21 CFR 886.1655 - Ophthalmic Fresnel prism.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ophthalmic Fresnel prism. 886.1655 Section 886.1655 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... provides the optical effect of a prism. The device is intended to be applied to spectacle lenses to give...

  11. Bragg-Fresnel optics: New field of applications

    SciTech Connect

    Snigirev, A.

    1997-02-01

    Bragg-Fresnel Optics shows excellent compatibility with the third generation synchrotron radiation sources such as ESRF and is capable of obtaining monochromatic submicron focal spots with 10{sup 8}-10{sup 9} photons/sec in an energy bandwidth of 10{sup -4}-10{sup -6} and in a photon energy range between 2-100 keV. New types of Bragg-Fresnel lenses like modified, ion implanted, bent and acoustically modulated were tested. Microprobe techniques like microdiffraction and microfluorescence based on Bragg-Fresnel optics were realised at the ESRF beamlines. Excellent parameters of the X-ray beam at the ESRF in terms of low emittance and quite small angular source size allow for Bragg-Fresnel optics to occupy new fields of applications such as high resolution diffraction, holography, interferometry and phase contrast imaging.

  12. Fresnel Concentrators for Space Solar Power and Solar Thermal Propulsion

    NASA Technical Reports Server (NTRS)

    Bradford, Rodney; Parks, Robert W.; Craig, Harry B. (Technical Monitor)

    2001-01-01

    Large deployable Fresnel concentrators are applicable to solar thermal propulsion and multiple space solar power generation concepts. These concentrators can be used with thermophotovoltaic, solar thermionic, and solar dynamic conversion systems. Thin polyimide Fresnel lenses and reflectors can provide tailored flux distribution and concentration ratios matched to receiver requirements. Thin, preformed polyimide film structure components assembled into support structures for Fresnel concentrators provide the capability to produce large inflation-deployed concentrator assemblies. The polyimide film is resistant to the space environment and allows large lightweight assemblies to be fabricated that can be compactly stowed for launch. This work addressed design and fabrication of lightweight polyimide film Fresnel concentrators, alternate materials evaluation, and data management functions for space solar power concepts, architectures, and supporting technology development.

  13. Ion implanted Bragg{endash}Fresnel lens

    SciTech Connect

    Souvorov, A.; Snigirev, A.; Snigireva, I.; Aristova, E.

    1996-05-01

    We have investigated the feasibility of widening the bandpath of the Bragg{endash}Fresnel optical element through the use of ion implantation. The focusing properties of Bragg{endash}Fresnel lenses (BFLs) were studied as a function of the implantation dose and energy. An enhancement of the focus intensity of up to 15{percent} was found, which is less than expected. Due to the complicated scattering of the low energy ions inside the micrometer- and submicrometer-sized crystal features that make up the BFL relief, the implantation technology destroys the peripheral zones of the BFL more than it increases the intensity in the focus. Nevertheless we believe that high energy implantation can be successfully used to modify the BFL reflectivity, especially in the case of nearly backscattering reflection. {copyright} {ital 1996 American Institute of Physics.}

  14. Study on light weight design of truss structures of spacecrafts

    NASA Astrophysics Data System (ADS)

    Zeng, Fuming; Yang, Jianzhong; Wang, Jian

    2015-08-01

    Truss structure is usually adopted as the main structure form for spacecrafts due to its high efficiency in supporting concentrated loads. Light-weight design is now becoming the primary concern during conceptual design of spacecrafts. Implementation of light-weight design on truss structure always goes through three processes: topology optimization, size optimization and composites optimization. During each optimization process, appropriate algorithm such as the traditional optimality criterion method, mathematical programming method and the intelligent algorithms which simulate the growth and evolution processes in nature will be selected. According to the practical processes and algorithms, combined with engineering practice and commercial software, summary is made for the implementation of light-weight design on truss structure for spacecrafts.

  15. Fresnel lens study

    SciTech Connect

    Not Available

    1986-05-01

    Thick film sol-gel technology was evaluated to determine the feasibility of utilizing sol-gels to produce embossable materials ultimately for the production of all-glass Fresnel optics. The feasibility study has utilized the relatively undeveloped branch of organically modified sol-gels. The results of this work shown that organically modified sol-gels posses properties which allow the formation of thick, patternable and adherent coatings. The study resulted in the fabrication of over 600 samples based on over 100 sol-gel formulations. Samples were evaluated for clarity, transmittance and other optical properties. Environmental tests were performed on selected groups. Although moderate success was obtained on producing a Fresnel lens layer bonded to glass, a fully densified lens was not achieved. The process and chemistries indicate that improvements based on these materials and techniques may lead to an acceptable all-glass Fresnel lens.

  16. Fresnel lens study

    NASA Astrophysics Data System (ADS)

    1986-05-01

    Thick film sol-gel technology was evaluated to determine the feasibility of utilizing sol-gels to produce embossable materials ultimately for the production of all-glass Fresnel optics. The feasibility study has utilized the relatively undeveloped branch of organically modified sol-gels. The results of this work show that organically modified sol-gels possess properties which allow the formation of thick, patternable and adherent coatings. The study resulted in the fabrication of over 600 samples based on over 100 sol-gel formulations. Samples were evaluated for clarity, transmittance and other optical properties. Environmental tests were performed on selected groups. Although moderate success was obtained on producing a Fresnel lens layer bonded to glass, a fully densified lens was not achieved. The process and chemistries indicate that improvements based on these materials and techniques may lead to an acceptable all-glass Fresnel lens.

  17. All-optical Fresnel lens in coherent media: controlling image with image.

    PubMed

    Zhao, L; Duan, Wenhui; Yelin, S F

    2011-01-17

    We theoretically explore an all-optical method for generating tunable diffractive Fresnel lenses in coherent media based on electromagnetically induced transparency. In this method, intensity-modulated images in coupling light fields can pattern the coherent media to induce the desired modulo-2π quadratic phase profiles for the lenses to diffract probe light fields. We characterize the focusing and imaging properties of the induced lenses. In particular, we show that the images in coupling fields can flexibly control the images in probe fields by diffraction, where large focal length tunability from 1 m to infinity and high output (∼ 88% diffraction efficiency) can be achieved. Additionally, we also find that the induced Fresnel lenses can be rapidly modulated with megahertz refresh rates using image-bearing square pulse trains in coupling fields. Our proposed lenses may find a wide range of applications for multimode all-optical signal processing in both the classical and quantum regimes.

  18. Electrically switchable holographic liquid crystal/polymer Fresnel lens using a Michelson interferometer.

    PubMed

    Jashnsaz, Hossein; Mohajerani, Ezeddin; Nemati, Hossein; Razavi, Seyed Hossein; Alidokht, Isa Ahmad

    2011-06-10

    A holographic technique for fabricating an electrically switchable liquid crystal/polymer composite Fresnel lens is reported. A Michelson interferometer is used to produce the required Fresnel pattern, by placing a convex lens into one path of the interferometer. Simplicity of the method and the possibility of fabricating different focal length lenses in a single arrangement are advantages of the method. The performance of the fabricated lens was demonstrated and its electro-optical properties were investigated for its primary focal length.

  19. The Fresnel Integrals Revisited

    ERIC Educational Resources Information Center

    Chen, Hongwei

    2009-01-01

    This note presents another elementary method to evaluate the Fresnel integrals. It is interesting to see that this technique is also strong enough to capture a number of pairs of parameter integrals. The main ingredients of the method are the consideration of some related derivatives and linear differential equations.

  20. 9-fold Fresnel-Köhler concentrator with Fresnel lens of variable focal point.

    PubMed

    Mendes-Lopes, João; Benítez, Pablo; Zamora, Pablo; Miñano, Juan C

    2014-06-30

    Non-uniform irradiance patterns over Multi-Junction Cells gives rise to power losses, especially when considering spectral irradiance distributions over different junctions. Thermal effects on Silicone-on-Glass lenses affect spectral irradiance distributions. A new Photovoltaic Concentrator (CPV), formed by nine optical channels, each one with a Köhler configuration, has been designed to overcome these effects at high concentrations for a large acceptance angle. A Fresnel Lens with a Variable Focal Point is proposed to prevent optical crosstalk in multichannel systems. When integrated into the concentrator, improves the acceptance angle. These designs are designed to fulfill the expected requirements of four junction CPV systems.

  1. Lensless zoomable holographic projection using scaled Fresnel diffraction.

    PubMed

    Shimobaba, Tomoyoshi; Makowski, Michal; Kakue, Takashi; Oikawa, Minoru; Okada, Naohisa; Endo, Yutaka; Hirayama, Ryuji; Ito, Tomoyoshi

    2013-10-21

    Projectors require a zoom function. This function is generally realized using a zoom lens module composed of many lenses and mechanical parts; however, using a zoom lens module increases the system size and cost, and requires manual operation of the module. Holographic projection is an attractive technique because it inherently requires no lenses, reconstructs images with high contrast and reconstructs color images with one spatial light modulator. In this paper, we demonstrate a lensless zoomable holographic projection. Without using a zoom lens module, this holographic projection realizes the zoom function using a numerical method, called scaled Fresnel diffraction which can calculate diffraction at different sampling rates on a projected image and hologram.

  2. Wave-front analysis using Fresnel lens arrays.

    PubMed

    Spektor, B; Shamir, J

    1995-07-01

    A compact wave-front sensor is implemented by an array of two-beam common path inversion interferometers. Each element of the array consists of two Fresnel lenses in a confocal configuration. The wave-front data can be extracted from a superposition of the zero-order undiffracted wave and the twice-diffracted first-order wave. The result is a high-sensitivity, compact, and stable interferometric wave-front sensor.

  3. Light-weight cyptography for resource constrained environments

    NASA Astrophysics Data System (ADS)

    Baier, Patrick; Szu, Harold

    2006-04-01

    We give a survey of "light-weight" encryption algorithms designed to maximise security within tight resource constraints (limited memory, power consumption, processor speed, chip area, etc.) The target applications of such algorithms are RFIDs, smart cards, mobile phones, etc., which may store, process and transmit sensitive data, but at the same time do not always support conventional strong algorithms. A survey of existing algorithms is given and new proposal is introduced.

  4. Tailored Buckling Microlattices as Reusable Light-Weight Shock Absorbers.

    PubMed

    Frenzel, Tobias; Findeisen, Claudio; Kadic, Muamer; Gumbsch, Peter; Wegener, Martin

    2016-07-01

    Structures and materials absorbing mechanical (shock) energy commonly exploit either viscoelasticity or destructive modifications. Based on a class of uniaxial light-weight geometrically nonlinear mechanical microlattices and using buckling of inner elements, either a sequence of snap-ins followed by irreversible hysteretic - yet repeatable - self-recovery or multistability is achieved, enabling programmable behavior. Proof-of-principle experiments on three-dimensional polymer microstructures are presented.

  5. Fresnel Lens Solar Concentrator Design Based on Geometric Optics and Blackbody Radiation Equations

    NASA Technical Reports Server (NTRS)

    Watson, Michael D.; Jayroe, Robert, Jr.

    1999-01-01

    Fresnel lenses have been used for years as solar concentrators in a variety of applications. Several variables effect the final design of these lenses including: lens diameter, image spot distance from the lens, and bandwidth focused in the image spot. Defining the image spot as the geometrical optics circle of least confusion and applying blackbody radiation equations the spot energy distribution can be determined. These equations are used to design a fresnel lens to produce maximum flux for a given spot size, lens diameter, and image distance. This approach results in significant increases in solar efficiency over traditional single wavelength designs.

  6. Fresnel Lens Characterization for Potential Use in an Unpiloted Atmospheric Vehicle DIAL Receiver System

    NASA Technical Reports Server (NTRS)

    Fastig, Shlomo; Deoung, Russell J.

    1998-01-01

    Acrylic plastic Fresnel lenses are very light and can have large diameters. Such lenses could be used in lidar telescope receivers if the focal spot is not too large or distorted. This research effort characterizes the focal spot diameter produced by a Fresnel lens with a diameter of 30.5 cm (12 in.). It was found that the focal spot diameter varied from 1.2 mm at 750 nm to 1.6 mm at 910 nm. The focal spot was irregular and not easily described by a Gaussian profile.

  7. Fresnel diffraction by spherical obstacles

    NASA Technical Reports Server (NTRS)

    Hovenac, Edward A.

    1989-01-01

    Lommel functions were used to solve the Fresnel-Kirchhoff diffraction integral for the case of a spherical obstacle. Comparisons were made between Fresnel diffraction theory and Mie scattering theory. Fresnel theory is then compared to experimental data. Experiment and theory typically deviated from one another by less than 10 percent. A unique experimental setup using mercury spheres suspended in a viscous fluid significantly reduced optical noise. The major source of error was due to the Gaussian-shaped laser beam.

  8. Development of a low-cost extrusion-embossing process for a linear Fresnel lens photovoltaic concentration

    SciTech Connect

    Not Available

    1984-09-01

    Results of efforts to fabricate linear Fresnel lens using a low-cost extrusion-embossing process indicated that the extrusion-embossing process will be difficult to adapt to the manufacture of efficient lenses. Lenses produced in pilot runs acheived only 72% optical efficiency at 25X geometric concentration ratio, compared to 87% for lenses made by casting or Lensfilm processes. A highly accurate, yet simple, outdoor focal plane flux profile test apparatus was developed that can be used to qualify new lenses and to check the quality of production lenses.

  9. Design and development of a laminated glass-plastic Fresnel lens for point focus photovoltaic systems

    SciTech Connect

    Matalon, L. A.

    1982-08-01

    The design and development of a laminated glass-plastic Fresnel lens for point focus photovoltaic systems use is described. The objective of this development was to examine the feasibility of producing lenses with a cost effectiveness superior to that of lenses made by casting of acrylic. The procedure used in executing this development, the method used in cost effectiveness evaluation, results obtained and recommendations for further work are presented.

  10. a Light-Weight Laser Scanner for Uav Applications

    NASA Astrophysics Data System (ADS)

    Tommaselli, A. M. G.; Torres, F. M.

    2016-06-01

    Unmanned Aerial Vehicles (UAV) have been recognized as a tool for geospatial data acquisition due to their flexibility and favourable cost benefit ratio. The practical use of laser scanning devices on-board UAVs is also developing with new experimental and commercial systems. This paper describes a light-weight laser scanning system composed of an IbeoLux scanner, an Inertial Navigation System Span-IGM-S1, from Novatel, a Raspberry PI portable computer, which records data from both systems and an octopter UAV. The performance of this light-weight system was assessed both for accuracy and with respect to point density, using Ground Control Points (GCP) as reference. Two flights were performed with the UAV octopter carrying the equipment. In the first trial, the flight height was 100 m with six strips over a parking area. The second trial was carried out over an urban park with some buildings and artificial targets serving as reference Ground Control Points. In this experiment a flight height of 70 m was chosen to improve target response. Accuracy was assessed based on control points the coordinates of which were measured in the field. Results showed that vertical accuracy with this prototype is around 30 cm, which is acceptable for forest applications but this accuracy can be improved using further refinements in direct georeferencing and in the system calibration.

  11. Reflections From a Fresnel Lens

    ERIC Educational Resources Information Center

    Keeports, David

    2005-01-01

    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. These experiments provide…

  12. Ptychographic Fresnel coherent diffractive imaging

    SciTech Connect

    Vine, D. J.; Williams, G. J.; Nugent, K. A.; Abbey, B.; Pfeifer, M. A.; Clark, J. N.; Peele, A. G.; Jonge, M. D. de; McNulty, I.

    2009-12-15

    This paper reports improved reconstruction of complex wave fields from extended objects. The combination of ptychography with Fresnel diffractive imaging results in better reconstructions with fewer iterations required to convergence than either method considered separately. The method is applied to retrieve the projected thickness of a gold microstructure and comparative results using ptychography and Fresnel diffractive imaging are presented.

  13. Wavelength-independent integrated focus sensor using a reflection twin micro-Fresnel lens.

    PubMed

    Shiono, T; Setsune, K

    1989-12-01

    A compact focus sensor constructed with thin film components such as a reflection twin micro-Fresnel lens and a photodetector is proposed. This sensor has a folded optical path and is insensitive to wavelength shift. Theoretical analysis indicates that the optical performance of reflection Fresnel lenses can be improved in comparison with a conventional transmission micro-Fresnel lens. The reflection twin Fresnel lens was fabricated using electron-beam lithography and exhibited diffraction-limited focusing performance with high (71%) efficiency. It was demonstrated that the focus sensor had excellent spot displacement characteristics in agreement with theoretical results, and a focus error signal was detected. This focus sensor could be useful for the optical head of an optical disk system.

  14. An analytical and experimental investigation of a 1.8 by 3.7 meter Fresnel lens solar concentrator

    NASA Technical Reports Server (NTRS)

    Hastings, L. J.; Allums, S. L.; Jensen, W. S.

    1977-01-01

    Line-focusing acrylic Fresnel lenses with application potential in the 200-370 C range are being analytically and experimentally investigated. The measured solar concentration characteristics of a 1.8 by 3.7 m lens and its utilization in a solar collection mode are summarized in this paper. A peak concentration ratio of 64 with 90% of the transmitted energy focused into a 5 cm width was achieved and demonstrated the feasibility of the Fresnel lens solar concentrator concept.

  15. A Signcryption based Light Weight Key Exchange Protocol

    NASA Astrophysics Data System (ADS)

    Feng, Yong; Wei, Qian; Zhang, Xing

    Traditional cryptography based authenticated Diffie-Hellman key exchange protocols expose the problems of efficiency and privacy since signature-then-encryption is heavy to wireless communication special for flexible dynamic deployment, i.e., wireless mesh networks, wireless sensor networks, mobile ad hoc networks, etc., in computational cost and communicational overhead and traditional digital signature allows anyone to verify its validity using the corresponding public key. In this paper, we propose a signcryption based light weight key exchange protocol named SLWKE which can provide resistance to traditional attacks, i.e., eavesdropping, deducing, replaying, interleaving, forging and repudiating, and unknown key-share attack and save computational cost by three modular calculations, i.e., one modular inversion, one modular addition and one modular multiplicative, included in a signature s and communicational overhead by secure length of IqI in comparison to signcryption based direct key exchange using a time-stamp protocol termed Dkeuts.

  16. A study for the special Fresnel lens for high efficiency solar concentrators

    NASA Astrophysics Data System (ADS)

    Lin, Jian-Shian; Huang, Wei-Chih; Hsu, Hsiu-Chen; Chang, Ming-Wen; Liu, Chung-Ping

    2005-08-01

    Design a Fresnel lens for a concentrator to collect more sunlight onto the solar cell due to the efficiency and cost. Since 1970, the non-imaging concentrator was used for solar energy; most of them were reflecting mirrors. The non-imaging optical system provides large aperture and forgiving imaging requirements. The Fresnel lens used in non-imaging optical system was usually called non-imaging Fresnel lens. In this research, the Fresnel lenses were refracting optical elements but diffracting ones. According to the method of Ralf Leutz and Akio Suzuki [2], using minimum deviation and minimum dispersion to design a non-imaging Fresnel lens, which obeys the edge ray principle. Use optical software TracePro to simulate the non-imaging Fresnel lens, and each pitch size was 0.3mm and 200mm focus distant. Discusses the losses of non-imaging Fresnel lens and find out the relation of efficiency and F-Number. The optical concentration ratio could reach 15X (2-D) and 230X (3-D).

  17. Shallow Fresnel lens fabrication using grayscale lithography made by high energy beam sensitive mask (HEBS) technology and reactive ion etching

    NASA Astrophysics Data System (ADS)

    Nachmias, Tali; Ohayon, Avi; Meltzer, Shefer E.; Kabla, Meni; Louzon, Elie; Levy, Uriel

    2009-02-01

    We describe the fabrication and the characterization of high efficiency Fresnel lenses by the use of gray scale lithography (GSL), followed by reactive ion etching (RIE) or deep reactive ion etching (DRIE) to transfer the pattern from the gray scale resist into the silicon substrate. Three versions of Fresnel lenses were fabricated, with height of 600nm, 1800nm and 5500nm. The desired lens height in silicon is determined from photoresist height and the selectivity of the etching process. A low selectivity DRIE process was developed in order to fabricated 1800nm and 5500nm Fresnel lenses. The 600nm Fresnel lens was fabricated using an RIE process because it requires a relatively slow etch rate and low selectivity, both could not be obtained by DRIE. According to the photoresist thickness developed in the gray scale lithography, an RIE process with a selectivity of 0.55 was required. We implement the DOE (design of experiment) method for finding the process parameters which gives the desirable selectivity and its tolerance which is crucial for determining the range of the Fresnel lens height. It was found that according to the selectivity tolerance, the Fresnel lens stands within +/-10% tolerance of its height. Finally, we demonstrated the imaging of an object using the 600 nm lens.

  18. Dispersion-compensated Fresnel lens

    DOEpatents

    Johnson, K.C.

    1992-11-03

    A transmission grating is used to reduce chromatic aberration in a Fresnel lens, wherein the lens chromatic dispersion is offset and substantially canceled by the grating's diffraction-induced dispersion. The grating comprises a Fresnel-type pattern of microscopic facets molded directly into the lens surface. The facets would typically have a profile height of around 4[times]10[sup [minus]5] inch and a profile width of at least 10[sup [minus]3] inch. In its primary intended application, the invention would function to improve the optical performance of a Fresnel lens used to concentrate direct sunlight. 10 figs.

  19. Dispersion-compensated fresnel lens

    DOEpatents

    Johnson, Kenneth C.

    1992-01-01

    A transmission grating is used to reduce chromatic aberration in a Fresnel lens, wherein the lens chromatic dispersion is offset and substantially canceled by the grating's diffraction-induced dispersion. The grating comprises a Fresnel-type pattern of microscopic facets molded directly into the lens surface. The facets would typically have a profile height of around 4.multidot.10.sup.-5 inch and a profile width of at least 10.sup.-3 inch. In its primary intended application, the invention would function to improve the optical performance of a Fresnel lens used to concentrate direct sunlight.

  20. Deployable Fresnel Rings

    NASA Technical Reports Server (NTRS)

    Kennedy, Timothy F.; Fink, Patrick W.; Chu, Andrew W.; Lin, Gregory Y.

    2014-01-01

    Deployable Fresnel rings (DFRs) significantly enhance the realizable gain of an antenna. This innovation is intended to be used in combination with another antenna element, as the DFR itself acts as a focusing or microwave lens element for a primary antenna. This method is completely passive, and is also completely wireless in that it requires neither a cable, nor a connector from the antenna port of the primary antenna to the DFR. The technology improves upon the previous NASA technology called a Tri-Sector Deployable Array Antenna in at least three critical aspects. In contrast to the previous technology, this innovation requires no connector, cable, or other physical interface to the primary communication radio or sensor device. The achievable improvement in terms of antenna gain is significantly higher than has been achieved with the previous technology. Also, where previous embodiments of the Tri-Sector antenna have been constructed with combinations of conventional (e.g., printed circuit board) and conductive fabric materials, this innovation is realized using only conductive and non-conductive fabric (i.e., "e-textile") materials, with the possible exception of a spring-like deployment ring. Conceptually, a DFR operates by canceling the out-of-phase radiation at a plane by insertion of a conducting ring or rings of a specific size and distance from the source antenna, defined by Fresnel zones. Design of DFRs follow similar procedures to those outlined for conventional Fresnel zone rings. Gain enhancement using a single ring is verified experimentally and through computational simulation. The experimental test setup involves a microstrip patch antenna that is directly behind a single-ring DFR and is radiating towards a second microstrip patch antenna. The first patch antenna and DFR are shown. At 2.42 GHz, the DFR improves the transmit antenna gain by 8.6 dB, as shown in Figure 2, relative to the wireless link without the DFR. A figure illustrates the

  1. A New Light Weight Structural Material for Nuclear Structures

    SciTech Connect

    Rabiei, Afsaneh

    2016-01-14

    Radiation shielding materials are commonly used in nuclear facilities to attenuate the background ionization radiations to a minimum level for creating a safer workplace, meeting regulatory requirements and maintaining high quality performance. The conventional radiation shielding materials have a number of drawbacks: heavy concrete contains a high amount of elements that are not desirable for an effective shielding such as oxygen, silicon, and calcium; a well known limitation of lead is its low machinability and toxicity, which is causing a major environmental concern. Therefore, an effective and environmentally friendly shielding material with increased attenuation and low mass density is desirable. Close-cell composite metal foams (CMFs) and open-cell Al foam with fillers are light-weight candidate materials that we have studied in this project. Close-cell CMFs possess several suitable properties that are unattainable by conventional radiation shielding materials such as low density and high strength for structural applications, high surface area to volume ratio for excellent thermal isolation with an extraordinary energy absorption capability. Open-cell foam is made up of a network of interconnected solid struts, which allows gas or fluid media to pass through it. This unique structure provided a further motive to investigate its application as radiation shields by infiltrating original empty pores with high hydrogen or boron compounds, which are well known for their excellent neutron shielding capability. The resulting open-cell foam with fillers will not only exhibit light weight and high specific surface area, but also possess excellent radiation shielding capability and good processability. In this study, all the foams were investigated for their radiation shielding efficiency in terms of X-ray, gamma ray and neutron. X-ray transmission measurements were carried out on a high-resolution microcomputed tomography (microCT) system. Gamma-emitting sources: 3.0m

  2. Novel light-weight materials for shielding gamma ray

    NASA Astrophysics Data System (ADS)

    Chen, Shuo; Bourham, Mohamed; Rabiei, Afsaneh

    2014-03-01

    A comparison of gamma ray attenuation effectiveness of bulk aluminum, close-cell composite metal foams and open-cell aluminum foam infiltrated with variety of second phase materials were investigated and reported in this study. Mass attenuation coefficients for six sets of samples with three different areal densities of 2, 5 and 10 g/cm2 were determined at photon energies of 0.060, 0.662, 1.173, and 1.332 MeV. Theoretical values were calculated using XCOM software package. A complete agreement was observed between experimental and theoretical results. It is observed that close-cell composite metal foams exhibit a better shielding capability compared to open-cell Al foam with fillers. It is also observed that close-cell composite metal foams offer superior shielding effectiveness compared to bulk aluminum for energies below 0.662 MeV, the mass attenuation coefficients of steel-steel composite metal foam and Al-steel composite metal foam were measured 400 and 300% higher than that of aluminum A356. This study indicates the potential of utilizing the light-weight composite metal foams as shielding material replacing current heavy materials used for attenuation of low energy gamma ray with additional advantages such as high energy absorption and excellent heat rejection capabilities.

  3. Fresnel-Gaussian shape invariant for optical ray tracing.

    PubMed

    Cywiak, Moisés; Morales, A; Flores, J Mauricio; Servín, Manuel

    2009-06-22

    We propose a technique for ray tracing, based in the propagation of a Gaussian shape invariant under the Fresnel diffraction integral. The technique uses two driving independent terms to direct the ray and is based on the fact that at any arbitrary distance, the center of the propagated Gaussian beam corresponds to the geometrical projection of the center of the incident beam. We present computer simulations as examples of the use of the technique consisting in the calculation of rays through lenses and optical media where the index of refraction varies as a function of position.

  4. Lensless phase contrast microscopy based on multiwavelength Fresnel diffraction.

    PubMed

    Noom, Daniel W E; Eikema, Kjeld S E; Witte, Stefan

    2014-01-15

    We demonstrate a compact, wide-field, quantitative phase contrast microscope that does not require lenses for image formation. High-resolution images are retrieved from Fresnel diffraction patterns recorded at multiple wavelengths, combined with a robust iterative phase retrieval algorithm. Quantitative phase contrast images of living cultured neurons are obtained with a transverse resolution of <2 μm. Our system is well suited for high-resolution live cell imaging and provides a compact, cost-effective alternative to full-sized phase-contrast microscopes.

  5. Integrated Fresnel lens on thermally oxidized silicon substrate.

    PubMed

    Mottier, P; Valette, S

    1981-05-01

    Thin film Fresnel lenses have been achieved on SiO(2)/Si substrates covered with a waveguide layer of Si(3)N(4) grown by low pressure chemical vapor deposition (LPCVD). The phase shift between the different zones is induced by a SiO(2) top layer chemically etched. The use of this additional layer having a smaller refractive index than the waveguide results in a saturation of the lens characteristics vs the thickness of the SiO(2) layer; this feature associated with the good reproducibility of the LPCVD technology allows good control of the lens characteristics.

  6. Recent development of fabrication of extreme light-weighted ceramic mirrors

    NASA Astrophysics Data System (ADS)

    Krödel, Matthias; Wächter, Daniel; Stahr, Frank; Soose, Claus P.

    2015-09-01

    This paper will present the recent development achievements of a German SME supply chain to manufacture super light-weighted HB-Cesic® mirrors for IR to visible applications. We will present recent design developments for achieving extreme light-weighted mirror substrates with extremely high stiffness and performance and in the second part the newly established German supply chain for the manufacturing of such extreme light-weighted mirror substrates.

  7. Component and prototype panel testing of the mini-dome Fresnel lens photovoltaic concentrator array

    NASA Technical Reports Server (NTRS)

    Piszczor, Michael F.; Swartz, Clifford K.; O'Neill, Mark J.

    1990-01-01

    The mini-dome Fresnel lens concentrator array, a high-efficiency, lightweight space photovoltaic array concept, is described. The three critical elements of the array concept are the Fresnel lens concentrator, the prismatic cell power cover, and the photovoltaic cell. Prototype concentrator lenses have been fabricated and tested, with optical efficiencies reaching 90 percent. Work is progressing on the design and fabrication of the panel structure. The impact of recent advances in 30 percent-efficient multijunction photovoltaic cells on array performance is also discussed. Near-term performance goals of 300 w/sq m and 100 w/kg are now feasible.

  8. Experimental realization of the devil's vortex Fresnel lens with a programmable spatial light modulator

    PubMed Central

    Mitry, Mark; Doughty, Danielle C.; Chaloupka, Jan L.; Anderson, Matthew E.

    2015-01-01

    We present a unique method for experimentally generating multiple vortices by way of a devil's vortex lens combined with a Fresnel lens using a spatial light modulator. These lenses have the multifocal properties of fractal zone plates combined with the orbital angular momentum of a spiral phase plate and can be tailored to fit within a small space on an optical bench. Results are presented alongside numerical simulations, demonstrating the robust nature of both the experimental method and the predictive power of the Huygens–Fresnel wavelet theory. PMID:22722286

  9. Experimental realization of the devil's vortex Fresnel lens with a programmable spatial light modulator.

    PubMed

    Mitry, Mark; Doughty, Danielle C; Chaloupka, Jan L; Anderson, Matthew E

    2012-06-20

    We present a unique method for experimentally generating multiple vortices by way of a devil's vortex lens combined with a Fresnel lens using a spatial light modulator. These lenses have the multifocal properties of fractal zone plates combined with the orbital angular momentum of a spiral phase plate and can be tailored to fit within a small space on an optical bench. Results are presented alongside numerical simulations, demonstrating the robust nature of both the experimental method and the predictive power of the Huygens-Fresnel wavelet theory.

  10. Software architecture of the light weight kernel, catamount.

    SciTech Connect

    Kelly, Suzanne Marie

    2005-05-01

    Catamount is designed to be a low overhead operating system for a parallel computing environment. Functionality is limited to the minimum set needed to run a scientific computation. The design choices and implementations will be presented. A massively parallel processor (MPP), high performance computing (HPC) system is particularly sensitive to operating system overhead. Traditional, multi-purpose, operating systems are designed to support a wide range of usage models and requirements. To support the range of needs, a large number of system processes are provided and are often interdependent on each other. The overhead of these processes leads to an unpredictable amount of processor time available to a parallel application. Except in the case of the most embarrassingly parallel of applications, an MPP application must share interim results with its peers before it can make further progress. These synchronization events are made at specific points in the application code. If one processor takes longer to reach that point than all the other processors, everyone must wait. The overall finish time is increased. Sandia National Laboratories began addressing this problem more than a decade ago with an architecture based on node specialization. Sets of nodes in an MPP are designated to perform specific tasks, each running an operating system best suited to the specialized function. Sandia chose to not use a multi-purpose operating system for the computational nodes and instead began developing its first light weight operating system, SUNMOS, which ran on the compute nodes on the Intel Paragon system. Based on its viability, the architecture evolved into the PUMA operating system. Intel ported PUMA to the ASCI Red TFLOPS system, thus creating the Cougar operating system. Most recently, Cougar has been ported to Cray's XT3 system and renamed to Catamount. As the references indicate, there are a number of descriptions of the predecessor operating systems. While the majority

  11. An optimized Fresnel array for a test space mission in UV

    NASA Astrophysics Data System (ADS)

    Roux, W.; Koechlin, L.

    2016-07-01

    The Fresnel Diffractive Imager is based on a new optical concept for space telescopes, developed at Institut de Recherche en Astrophysique et Planétologie (IRAP) in Toulouse, France. We propose it for space missions dedicated to science cases in the Ultra-Violet with aperture ranges from 6 to 30 meters. Instead of a classical mirror to focus light, this concept uses very light-weight diffractive optics : the Fresnel array. Our project has already proved its performances in terms of resolution and high dynamic range in the laboratory, in the visible and near IR. It has been tested successfully on real astrophysical sources from the ground. At present, the project has reached the stage where a probatory mission is needed to validate its operation in space. In collaboration with institutes in Spain and Russia, we will propose a mission to the Russian space agency Roscosmos, to board a small prototype Fresnel imager on the International Space Station (ISS) for a UV astronomy program. We have improved the Fresnel array design to get a better Point Spread Function (PSF), 2 different ways. Numerical simulations have first allowed us to confirm these optical improvements, before manufacturing the diffractive optics and using them for new lab tests. In our previous setups, the opaque Fresnel zones in the primary Fresnel array (playing the role of the telescope objective) were maintained with an orthogonal bars mesh, following the pseudo-period of the Fresnel zones. We show that the PSF improves when these bars are regularly spaced. Furthermore, the optical system is apodized to get a better peaked PSF, and increase its high contrast performances. In our case, to apodize a binary mask the solution is to modulate the Fresnel zones in relative thickness ratio (opaque versus void), thus driving the local light transmission ratio. In earlier implementations, our Fresnel arrays were apodized with a circularly symmetric law, but an orthogonal apodization law is more efficient

  12. Efficient Fresnel x-ray optics made simple

    SciTech Connect

    Braig, Christoph; Predehl, Peter

    2007-05-10

    A practical design for upcoming spaceborne x-ray telescopes with ultrahigh angular resolution is proposed. Particular attention is directed to technological simplicity and robust as well as cheap components. Based on dispersion corrected Fresnel lenses, an optimized arrangement will be identified with respect to the instrumental sensitivity for a given focal spot size. We show that this optical Gamow peak essentially depends on the radial transmission profile of a diffractive-refractive aperture. Examples for energies above 4 keV illustrate astronomical capabilities for large-scale compact and segmented objectives as well. The spectral and spatial resolutions of conventional semiconductor detectors are very well matched to imaging characteristics of those achromatic lenses. The constraints to fabrication techniques using most promising materials like Li, Be, and plastics are discussed.

  13. Types of Contact Lenses

    MedlinePlus

    ... Consumer Devices Consumer Products Contact Lenses Types of Contact Lenses Share Tweet Linkedin Pin it More sharing ... Orthokeratology (Ortho-K) Decorative (Plano) Contact Lenses Soft Contact Lenses Soft contact lenses are made of soft, ...

  14. The design and development of a high concentration and high efficiency photovoltaic concentrator utilizing a curved Fresnel lens

    SciTech Connect

    Moffat, A.L.; Scharlack, R.S.

    1982-09-01

    The design and development of an innovative photovoltaic concentrator which utilizes a low cost molded Fresnel lens is described. The lens design and fabrication are discussed, as well as the design of the collector module and tracking structure. A description of instrumentation developed to aid in the testing of lenses and solar cells is presented, and includes the test results.

  15. Arbitrary shape surface Fresnel diffraction.

    PubMed

    Shimobaba, Tomoyoshi; Masuda, Nobuyuki; Ito, Tomoyoshi

    2012-04-09

    Fresnel diffraction calculation on an arbitrary shape surface is proposed. This method is capable of calculating Fresnel diffraction from a source surface with an arbitrary shape to a planar destination surface. Although such calculation can be readily calculated by the direct integral of a diffraction calculation, the calculation cost is proportional to O(N²) in one dimensional or O(N⁴) in two dimensional cases, where N is the number of sampling points. However, the calculation cost of the proposed method is O(N log N) in one dimensional or O(N² log N) in two dimensional cases using non-uniform fast Fourier transform.

  16. Optimal design of an irregular Fresnel lens for multiple light sources using a three-layered Hierarchical Genetic Algorithm.

    PubMed

    Chen, Wen-Gong; Uang, Chii-Maw; Jou, Chen-Hai

    2007-08-06

    A two-layered Hierarchical Genetic Algorithm (HGA) was proposed in a previous paper to solve the design problem of a large scale Fresnel lens used in a multiple-source lighting system. The research objective of this paper is to extend the previous work by utilizing a three-layered HGA. The goal of the suggested approach is to decrease the reliance on deciding the number of groove segments for the designed Fresnel lenses, as well as to increase the variety of groove angles in a segment to improve the performance of the designed Fresnel lens. The proposed algorithm will be applied on a simulated reading light system, and the simulation results demonstrate that the proposed approach not only makes the design of a large scale Fresnel lens more feasible but also works better than the previous one in both illuminance and uniformity for a simulated reading light system.

  17. Design and modeling of a cost-effective achromatic Fresnel lens for concentrating photovoltaics.

    PubMed

    Vallerotto, Guido; Victoria, Marta; Askins, Stephen; Herrero, Rebeca; Domínguez, César; Antón, Ignacio; Sala, Gabriel

    2016-09-05

    This paper presents a novel Fresnel lens capable of significantly reducing chromatic aberration in solar applications. The optical performance of this achromatic lens has been analyzed through ray-tracing simulations, showing a concentration factor three times higher than that attained by a classic silicone on glass (SOG) Fresnel lens while maintaining the same acceptance angle. This should avoid the need for a secondary optical element, reducing the cost associated with its manufacturing and assembly and increasing the module reliability. The achromatic lens is made of inexpensive plastic and elastomer which allows a highly scalable and cost-competitive manufacturing process similar to the one currently used for the fabrication of SOG Fresnel lenses.

  18. CPV module with Fresnel lens primary optics and homogenizing secondary optics

    NASA Astrophysics Data System (ADS)

    Wiesenfarth, Maike; Dörsam, Tobias; Eltermann, Fabian; Hornung, Thorsten; Siefer, Gerald; Steiner, Marc; van Riesen, Sascha; Neubauer, Martin; Boos, Alexander; Wanka, Sven; Gombert, Andreas; Bett, Andreas W.

    2015-09-01

    In this work CPV modules based on Fresnel lenses and using refractive secondary optical elements (SOEs) are investigated. Pure silicone as well as glass SOEs glued on top of the solar cells are explored in prototype modules. They are differently manufactured in respect to how the secondary optics was assembled. For example, units with secondary silicone optics directly casted to solar cells are manufactured. For a design of glued glass optics and Fresnel lenses, the optical design is analyzed experimentally. Moreover, the long term stability has been intensively tested by accelerated aging tests and outdoor experiments. Here, the focus was on the used silicone material and the adhesion of the silicone to the glass interface.

  19. An analytical and experimental evaluation of the plano-cylindrical Fresnel lens solar concentrator

    NASA Technical Reports Server (NTRS)

    Hastings, L. J.; Allums, S. L.; Cosby, R. M.

    1976-01-01

    Plastic Fresnel lenses for solar concentration are attractive because of potential for low-cost mass production. An analytical and experimental evaluation of line-focusing Fresnel lenses with application potential in the 200 to 370 C range is reported. Analytical techniques were formulated to assess the solar transmission and imaging properties of a grooves-down lens. Experimentation was based primarily on a 56 cm-wide lens with f-number 1.0. A sun-tracking heliostat provided a non-moving solar source. Measured data indicated more spreading at the profile base than analytically predicted. The measured and computed transmittances were 85 and 87% respectively. Preliminary testing with a second lens (1.85 m) indicated that modified manufacturing techniques corrected the profile spreading problem.

  20. Fresnel Diffraction for CTR Microbunching

    SciTech Connect

    Tikhoplav, R.; Knyazik, A.; Rosenzweig, J. B.; Andonian, G.

    2009-01-22

    Laser beams of high intensities are routinely used for IFEL experiments. Such beams can potentially destroy microbunching diagnostic tools such as coherent transition radiation foils due to their low damage thresholds. Near-field Fresnel diffraction scheme for termination of CO{sub 2} laser beam has been experimentally studied and is presented in this paper. Novel THz camera was utilized for such study.

  1. Novel Scanning Lens Instrument for Evaluating Fresnel Lens Performance: Equipment Development and Initial Results (Presentation)

    SciTech Connect

    Herrero, R.; Miller, D. C.; Kurtz, S. R.; Anton, I.; Sala, G.

    2013-07-01

    A system dedicated to the optical transmittance characterization of Fresnel lenses has been developed at NREL, in collaboration with the UPM. The system quantifies the optical efficiency of the lens by generating a performance map. The shape of the focused spot may also be analyzed to understand change in the lens performance. The primary instrument components (lasers and CCD detector) have been characterized to confirm their capability for performing optical transmittance measurements. Measurements performed on SoG and PMMA lenses subject to a variety of indoor conditions (e.g., UV and damp heat) identified differences in the optical efficiency of the evaluated lenses, demonstrating the ability of the Scanning Lens Instrument (SLI) to distinguish between the aged lenses.

  2. A novel scanning lens instrument for evaluating Fresnel lens performance: Equipment development and initial results

    NASA Astrophysics Data System (ADS)

    Herrero, Rebeca; Miller, David C.; Kurtz, Sarah R.; Antón, Ignacio; Sala, Gabriel

    2013-09-01

    A system dedicated to the optical transmittance characterization of Fresnel lenses has been developed at NREL, in collaboration with the UPM. The system quantifies the optical efficiency of the lens by generating a performance map. The shape of the focused spot may also be analyzed to understand change in the lens performance. The primary instrument components (lasers and CCD detector) have been characterized to confirm their capability for performing optical transmittance measurements. Measurements performed on SoG and PMMA lenses subject to a variety of indoor conditions (e.g., UV and damp heat) identified differences in the optical efficiency of the evaluated lenses, demonstrating the ability of the Scanning Lens Instrument (SLI) to distinguish between the aged lenses.

  3. Design and development of laminated Fresnel lens parquet for point-focus PV systems

    SciTech Connect

    Baum, B.; Holley, W.H.; Galica, J.P.; Thoma, L.A.

    1987-05-01

    Materials were identified and techniques developed to adhere acrylic Fresnel lenses to low-iron glass with a bond that has the potential to survive 20 years of outdoor weathering in a photovoltaic concentrator module. Candidate adhesive materials were screened and evaluated. Of all the adhesives evaluated, two types, silicone and ethylene vinyl acetate coploymer, were found to provide the best bond while possessing the optimum optical properties of lens alone.

  4. Compact, light-weight and cost-effective microscope based on lensless incoherent holography for telemedicine applications.

    PubMed

    Mudanyali, Onur; Tseng, Derek; Oh, Chulwoo; Isikman, Serhan O; Sencan, Ikbal; Bishara, Waheb; Oztoprak, Cetin; Seo, Sungkyu; Khademhosseini, Bahar; Ozcan, Aydogan

    2010-06-07

    Despite the rapid progress in optical imaging, most of the advanced microscopy modalities still require complex and costly set-ups that unfortunately limit their use beyond well equipped laboratories. In the meantime, microscopy in resource-limited settings has requirements significantly different from those encountered in advanced laboratories, and such imaging devices should be cost-effective, compact, light-weight and appropriately accurate and simple to be usable by minimally trained personnel. Furthermore, these portable microscopes should ideally be digitally integrated as part of a telemedicine network that connects various mobile health-care providers to a central laboratory or hospital. Toward this end, here we demonstrate a lensless on-chip microscope weighing approximately 46 grams with dimensions smaller than 4.2 cm x 4.2 cm x 5.8 cm that achieves sub-cellular resolution over a large field of view of approximately 24 mm(2). This compact and light-weight microscope is based on digital in-line holography and does not need any lenses, bulky optical/mechanical components or coherent sources such as lasers. Instead, it utilizes a simple light-emitting-diode (LED) and a compact opto-electronic sensor-array to record lensless holograms of the objects, which then permits rapid digital reconstruction of regular transmission or differential interference contrast (DIC) images of the objects. Because this lensless incoherent holographic microscope has orders-of-magnitude improved light collection efficiency and is very robust to mechanical misalignments it may offer a cost-effective tool especially for telemedicine applications involving various global health problems in resource limited settings.

  5. Compact, Light-weight and Cost-effective Microscope based on Lensless Incoherent Holography for Telemedicine Applications

    PubMed Central

    Mudanyali, Onur; Tseng, Derek; Oh, Chulwoo; Isikman, Serhan O.; Sencan, Ikbal; Bishara, Waheb; Oztoprak, Cetin; Seo, Sungkyu; Khademhosseini, Bahar; Ozcan, Aydogan

    2010-01-01

    Despite the rapid progress in optical imaging, most of the advanced microscopy modalities still require complex and costly set-ups that unfortunately limit their use beyond well equipped laboratories. In the meantime, microscopy in resource-limited settings has requirements significantly different from those encountered in advanced laboratories, and such imaging devices should be cost-effective, compact, light-weight and appropriately accurate and simple to be usable by minimally trained personnel. Furthermore, these portable microscopes should ideally be digitally integrated as part of a telemedicine network that connects various mobile health-care providers to a central laboratory or hospital. Toward this end, here we demonstrate a lensless on-chip microscope weighing ~46 grams with dimensions smaller than 4.2cm × 4.2cm × 5.8cm that achieves sub-cellular resolution over a large field of view of ~24 mm2. This compact and light-weight microscope is based on digital in-line holography and does not need any lenses, bulky optical/mechanical components or coherent sources such as lasers. Instead, it utilizes a simple light-emitting-diode (LED) and a compact opto-electronic sensor-array to record lensless holograms of the objects, which then permits rapid digital reconstruction of regular transmission or differential interference contrast (DIC) images of the objects. Because this lensless incoherent holographic microscope has orders-of-magnitude improved light collection efficiency and is very robust to mechanical misalignments it may offer a cost-effective tool especially for telemedicine applications involving various global health problems in resource limited settings. PMID:20401422

  6. Fabrication of wedged multilayer Laue lenses

    SciTech Connect

    Prasciolu, M.; Leontowich, A. F. G.; Krzywinski, J.; Andrejczuk, A.; Chapman, H. N.; Bajt, S.

    2015-01-01

    We present a new method to fabricate wedged multilayer Laue lenses, in which the angle of diffracting layers smoothly varies in the lens to achieve optimum diffracting efficiency across the entire pupil of the lens. This was achieved by depositing a multilayer onto a flat substrate placed in the penumbra of a straight-edge mask. The distance between the mask and the substrate was calibrated and the multilayer Laue lens was cut in a position where the varying layer thickness and the varying layer tilt simultaneously satisfy the Fresnel zone plate condition and Bragg’s law for all layers in the stack. This method can be used to extend the achievable numerical aperture of multilayer Laue lenses to reach considerably smaller focal spot sizes than achievable with lenses composed of parallel layers.

  7. Fabrication of wedged multilayer Laue lenses

    DOE PAGES

    Prasciolu, M.; Leontowich, A. F. G.; Krzywinski, J.; ...

    2015-01-01

    We present a new method to fabricate wedged multilayer Laue lenses, in which the angle of diffracting layers smoothly varies in the lens to achieve optimum diffracting efficiency across the entire pupil of the lens. This was achieved by depositing a multilayer onto a flat substrate placed in the penumbra of a straight-edge mask. The distance between the mask and the substrate was calibrated and the multilayer Laue lens was cut in a position where the varying layer thickness and the varying layer tilt simultaneously satisfy the Fresnel zone plate condition and Bragg’s law for all layers in the stack.more » This method can be used to extend the achievable numerical aperture of multilayer Laue lenses to reach considerably smaller focal spot sizes than achievable with lenses composed of parallel layers.« less

  8. Light-Weight, Single-Phase, Liquid-Cooled Cold Plate (Presentation)

    SciTech Connect

    Narumanchi, S.

    2013-07-01

    This presentation, 'Light-Weight, Low-Cost, Single-Phase Liquid-Cooled Cold Plate,' directly addresses program goals of increased power density, specific power, and lower cost of power electronics components through improved thermal management.

  9. Light-Weight, Low-Cost, Single-Phase, Liquid-Cooled Cold Plate (Presentation)

    SciTech Connect

    Narumanchi, S.

    2013-07-01

    This presentation, 'Light-Weight, Low-Cost, Single-Phase Liquid-Cooled Cold Plate,' directly addresses program goals of increased power density, specific power, and lower cost of power electronics components through improved thermal management.

  10. Focusing high-energy x rays by compound refractive lenses.

    PubMed

    Snigirev, A; Kohn, V; Snigireva, I; Souvorov, A; Lengeler, B

    1998-02-01

    Compound lenses made from low-Z materials (e.g., Be, B, C, and Al) set up as a linear array of refractive lenses are proposed for submicrometer focusing of high-energy x rays (>5 keV) in one or two dimensions. A theory of focusing based on Maxwell's equation and the Fresnel-Kirchhoff approach is presented. Compound refractive lenses were manufactured by drilling into an Al block a linear array of 200 closely spaced holes 0.5 mm in diameter for linear focusing and two crossed arrays of 100 holes each for point focusing. Focal spots of 3.7 mum and 8 mum x 18 mum were obtained at 30 keV for linear and two-dimensional lenses, respectively. Different technologies of manufacturing and possible applications of the proposed lenses are discussed.

  11. Polymer/Carbon Nanotube Networks for Smart, Self-Repairing and Light-Weighted Nanocomposites

    DTIC Science & Technology

    2012-11-05

    was develop smart, strong, and light-weight polymer/carbon nanotube (CNT) composites which will sense tribologically induced damages and self-heal by...light-weight polymer/carbon nanotube (CNT) composites which will sense tribologically induced damages and self-heal by inhibiting such degradation...vol%). This might have been the reason, why we did not observe large difference in mechanical and tribological properties between virgin PS and PS/CNT

  12. Fresnel drag effect in fiber optic gyroscope

    NASA Technical Reports Server (NTRS)

    Vali, V.; Berg, M. F.; Shorthill, R. W.

    1978-01-01

    Consideration is given to the development of a low-noise fiber-optic ring interferometer gyroscope. A technique for measuring the Fresnel drag coefficient of optical fibers is described, and the accuracy of the technique is considered. An experiment is performed which allows verification of the Einstein velocity addition theorem to the first nonlinear term. An experimental setup for measuring Fresnel drag is described: it consists of a Sagnac interferometer and a Fresnel drag measurement configuration.

  13. Design and development of a high-concentration and high-efficiency photovoltaic concentrator using a curved Fresnel lens

    SciTech Connect

    Scharlack, R.S.; Moffat, A.

    1983-08-01

    Thermo Electron has designed a high concentration photovoltaic module that uses a domed, point-focus Fresnel lens. Their design, design optimization process, and results from lens and receiver tests are described in this report. A complete module has not been fabricated and probably will not be fabricated in the future; however, Thermo Electron's optical design, analysis, and testing of both secondary optical units and domed Fresnel lenses have made a significant contribution to our project. Tooling errors prevented the lens from reaching its potential efficiency by the end of the contract, and resolution of these tooling problems is currently being attempted with a follow-on contract, No. 68-9463.

  14. Shifted Fresnel diffraction for computational holography.

    PubMed

    Muffoletto, Richard P; Tyler, John M; Tohline, Joel E

    2007-04-30

    Fourier-based approaches to calculate the Fresnel diffraction of light provide one of the most efficient algorithms for holographic computations because this permits the use of the fast Fourier transform (FFT). This research overcomes the limitations on sampling imposed by Fourier-based algorithms by the development of a fast shifted Fresnel transform. This fast shifted Fresnel transform is used to develop a tiling approach to hologram construction and reconstruction, which computes the Fresnel propagation of light between parallel planes having different resolutions.

  15. Lensing duct

    DOEpatents

    Beach, Raymond J. , Benett

    1994-01-01

    A lensing duct to condense (intensify) light using a combination of front surface lensing and reflective waveguiding. The duct tapers down from a wide input side to a narrow output side, with the input side being lens-shaped and coated with an antireflective coating for more efficient transmission into the duct. The four side surfaces are uncoated, preventing light from escaping by total internal reflection as it travels along the duct (reflective waveguiding). The duct has various applications for intensifying light, such as in the coupling of diode array pump light to solid state lasing materials, and can be fabricated from inexpensive glass and plastic.

  16. Lensing duct

    DOEpatents

    Beach, R.J.; Benett, W.J.

    1994-04-26

    A lensing duct to condense (intensify) light using a combination of front surface lensing and reflective waveguiding is described. The duct tapers down from a wide input side to a narrow output side, with the input side being lens-shaped and coated with an antireflective coating for more efficient transmission into the duct. The four side surfaces are uncoated, preventing light from escaping by total internal reflection as it travels along the duct (reflective waveguiding). The duct has various applications for intensifying light, such as in the coupling of diode array pump light to solid state lasing materials, and can be fabricated from inexpensive glass and plastic. 3 figures.

  17. Demonstration of a PDMS based hybrid grating and Fresnel lens (G-Fresnel) device.

    PubMed

    Yang, Chuan; Shi, Kebin; Edwards, Perry; Liu, Zhiwen

    2010-11-08

    A hybrid device that we term G-Fresnel (i.e., grating and Fresnel) is demonstrated. It fuses the functions of a grating and a Fresnel lens into a single device. We have fabricated the G-Fresnel device by using polydimethylsiloxane (PDMS) based soft lithography. Three-dimensional surface profilometry has been performed to examine the device quality. We have also conducted optical characterizations to confirm its dual focusing and dispersing properties. The G-Fresnel can be useful for the development of miniature optical spectrometers as well as emerging optofluidic applications.

  18. Microfabrication of Fresnel zone plates by laser induced solid ablation

    NASA Astrophysics Data System (ADS)

    Rodrigues, Vanessa R. M.; Thomas, John; Santhosh, Chidangil; Ramachandran, Hema; Mathur, Deepak

    2016-07-01

    A novel and simple single-step method of inscribing optical elements on metal-coated transparent substrates is demonstrated. Laser induced solid ablation (LISA) demands very low laser energies (nJ), as can be amply provided by a femtosecond laser oscillator. Here, LISA is used to write Fresnel zone plates on indium and tungsten coated glass. With up to 100 zones, remarkable agreement is obtained between measured and expected values of the focal length. LISA has enabled attainment of focal spot sizes that are 38% smaller than what would be obtained using conventional lenses of the same numerical aperture. The simplicity with which a high degree of automation can readily be achieved using LISA makes this cost-effective method amenable to a wide variety of applications related to microfabrication of optical elements.

  19. Conception of a cheap infrared camera using a Fresnel lens

    NASA Astrophysics Data System (ADS)

    Grulois, Tatiana; Druart, Guillaume; Guérineau, Nicolas; Crastes, Arnaud; Sauer, Hervé; Chavel, Pierre

    2014-09-01

    Today huge efforts are made in the research and industrial areas to design compact and cheap uncooled infrared optical systems for low-cost imagery applications. Indeed, infrared cameras are currently too expensive to be widespread. If we manage to cut their cost, we expect to open new types of markets. In this paper, we will present the cheap broadband microimager we have designed. It operates in the long-wavelength infrared range and uses only one silicon lens at a minimal cost for the manufacturing process. Our concept is based on the use of a thin optics. Therefore inexpensive unconventional materials can be used because some absorption can be tolerated. Our imager uses a thin Fresnel lens. Up to now, Fresnel lenses have not been used for broadband imagery applications because of their disastrous chromatic properties. However, we show that working in a high diffraction order can significantly reduce chromatism. A prototype has been made and the performance of our camera will be discussed. Its characterization has been carried out in terms of modulation transfer function (MTF) and noise equivalent temperature difference (NETD). Finally, experimental images will be presented.

  20. Fresnel formulas as Lorentz transformations

    PubMed

    Monzon; Sanchez-Soto

    2000-08-01

    From a matrix formulation of the boundary conditions we obtain the fundamental invariant for an interface and a remarkably simple factorization of the interface matrix, which enables us to express the Fresnel coefficients in a new and compact form. This factorization allows us to recast the action of an interface between transparent media as a hyperbolic rotation. By exploiting the local isomorphism between SL(2, C) and the (3 + 1)-dimensional restricted Lorentz group SO(3, 1), we construct the equivalent Lorentz transformation that describes any interface.

  1. Liquid crystal Fresnel lens display

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Qian; Abhishek Kumar, Srivastava; Alwin Tam, Ming-Wai; Zheng, Zhi-Gang; Shen, Dong; Vladimir, Chigrinov G.; Kwok, Hoi-Sing

    2016-09-01

    A novel see-through display with a liquid crystal lens array was proposed. A liquid crystal Fresnel lens display (LCFLD) with a holographic screen was demonstrated. The proposed display system has high efficiency, simple fabrication, and low manufacturing cost due to the absence of a polarizer and color filter. Project supported by Partner State Key Laboratory on Advanced Displays and Optoelectronics Technologies HKUST, China, the National Natural Science Foundation of China (Grant Nos. 61435008 and 61575063), and the Fundamental Research Funds for the Central Universities, China (Grant No. WM1514036).

  2. Advanced lab on Fresnel equations

    NASA Astrophysics Data System (ADS)

    Petrova-Mayor, Anna; Gimbal, Scott

    2015-11-01

    This experimental and theoretical exercise is designed to promote students' understanding of polarization and thin-film coatings for the practical case of a scanning protected-metal coated mirror. We present results obtained with a laboratory scanner and a polarimeter and propose an affordable and student-friendly experimental arrangement for the undergraduate laboratory. This experiment will allow students to apply basic knowledge of the polarization of light and thin-film coatings, develop hands-on skills with the use of phase retarders, apply the Fresnel equations for metallic coating with complex index of refraction, and compute the polarization state of the reflected light.

  3. Demonstration of a Fresnel axicon

    SciTech Connect

    Gourley, Kevin; Golub, Ilya; Chebbi, Brahim

    2011-01-20

    We design and manufacture a Fresnel axicon (fraxicon) that generates a quasi-diffraction-free/Bessel beam with a large depth of field. The novel optical element is characterized with both coherent and incoherent light, and its behavior is compared with that of a classical axicon. While the fraxicon exhibits a strong interference pattern in the on-axis intensity distribution, it can be smoothed out when using broadband light, partial spatial coherence light, or by period randomization. As inexpensive, compact/lightweight, and low-absorption elements, fraxicons may find applications in imaging, illumination, and situations where low absorption and dispersion are important.

  4. A new method to decide the practical feature of Fresnel lens from the result of ultra-high refractive index method (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Shibuya, Masato; Hiramatsu, Takashi; Araki, Keisuke; Nakadate, Suezou; Fujii, Junki

    2016-10-01

    We propose a new method to decide the brazed feature of Fresnel lens from the result of high refractive index method. Traditionally the feature has been designed to satisfy the phase-difference function for a point object by having brazed surface relieves only on one side of the lens. Therefore the exit ray of the practical feature is different from that of high-index method even for this point object. Thus the aberration is changed. To solve this problem, we propose Fresnel lens having brazed feature on both sides. Studying the spherical Fresnel lens which collects sun light, we theoretically show how to decide the shape. Also by practical lens designing, we demonstrate the validity of our theory. The proposed method is useful to decide the brazed feature of Fresnel lens from the result of high refractive index method, especially for small view angle lenses.

  5. Durability of Poly(Methyl Methacrylate) Lenses Used in Concentrating Photovoltaic Technology (Revised) (Presentation)

    SciTech Connect

    Miller, D. C.; Carloni, J. D.; Pankow, J. W.; Gjersing, E. L.; To, B.; Packard, C. E.; Kennedy, C. E.; Kurtz, S. R.

    2012-01-01

    Concentrating photovoltaic (CPV) technology recently gained interest based on its expected low levelized cost of electricity, high efficiency, and scalability. Many CPV systems employ Fresnel lenses composed of poly(methyl methacrylate) (PMMA) to obtain a high optical flux density on the cell. The optical and mechanical durability of these lenses, however, is not well established relative to the desired surface life of 30 years. Our research aims to quantify the expected lifetime of PMMA in key market locations (FL, AZ, and CO).

  6. Optical design of the Fresnel lens for LED-driven flashlight.

    PubMed

    Chen, Yi-Cheng; Nian, Shih-Chih; Huang, Ming-Shyan

    2016-02-01

    The Fresnel lens is composed of micrometer-sized v-groove structures that determine the maximum illuminance and brightness uniformity of LED-driven flashlights, which are used in high-quality photography. The fabrication quality of the microstructures and the accuracy of the geometrical curvature of the Fresnel lens affect the optical characteristics of the emitted light traveling through the lens, which in turn determines the maximum illuminance and brightness uniformity. This paper presents a systematic design procedure for fabricating the Fresnel lens and investigates the influence of geometrical design and fabrication process on optical performance. The optical analysis was performed using the commercial software TracePro. The results revealed that a small tip radius of the v-groove microstructure facilitates brightness uniformity. Furthermore, both the simulation and the experimental results revealed that Fresnel lenses fabricated through injection molding or injection compression molding have either errors of microstructure height more than 3%-6% or curvature errors higher than 6%, which would affect the optical performance, especially the brightness uniformity.

  7. a Bragg Fresnel Focusing Mirror with AN Integrated Micro-Electromechanical Bender

    NASA Astrophysics Data System (ADS)

    Li, Youli; Yasa, Mario; Abu Samah, Zuruzi; MacDonald, Noel; Safinya, Cyrus

    2004-03-01

    We present a Bragg Fresnel focusing mirror optic with an integrated micro-bender fabricated using Micro-Electro-Mechanical Systems (MEMS) technology. The optics module of the device consists of Au linear Fresnel lenses deposited on an x-ray reflective multilayer substrate. The Fresnel zones are designed to diffractively focus x-rays sagitally whereas the substrate can be bent to focus x-rays in the meridional direction. The MEMS bender consists of a linear array of electrodes deposited in a trench etched on a silicon substrate. The optics module is bonded to the bender module to form an array of parallel plate capacitors with an air gap of order 20 micron. A DC bias on the capacitive actuator generates an electrostatic force which bends the Bragg Fresnel mirror. The capacitance between the mirror and the bender can be monitored in-situ for feedback control of the bias voltage on the capacitor array. This dynamic process permits precise control of the geometric shape of the mirror for optimal focusing. This high efficiency optic can be used in wide-ranging x-ray microscopy and micro-diffraction applications. (Work supported by NSF-DMR-0076357, DOE W-7405-ENG-34 and ONR N00014-00-1-0214)

  8. A Linear Single-Crystal Bragg-Fresnel Lens With SiO2 Surface Structure

    SciTech Connect

    Kuznetsov, S.; Yunkin, V.; Drakopoulos, M.; Snigireva, I.; Snigirev, A.

    2004-05-12

    Bragg-Fresnel lens (BFL) as thin silicon dioxide strips grown on the surface of perfect silicon crystal was designed, manufactured and experimentally tested. In this case the BFL structure consists of a set of silicon dioxide rectangular shape etched zones arranged by the Fresnel zone law. The stress within coated and uncoated crystal regions is opposite in sign, whether tensile or compressive. The strain in the substrate crystal lattice directly underneath discontinuities in the deposited film give rise to phase difference between waves diffracted from coated and uncoated crystal regions. This phase difference is known to be dependent on the thickness and composition of film and substrate. The focusing properties of Si/SiO2 BFLs with 107 zones and 0.3 micrometer outermost zone width were experimentally studied as a function of the silicon oxide thickness in the range of 100 - 400 nanometers. It was shown that deformation Bragg-Fresnel lenses could effectively focus hard X-rays to a linear focal spot of about 2 microns. The efficiency of focusing was found to be about 16% at energy 10 keV. The developed lens design is a promising approach to extend the angular range of focusing by Bragg-Fresnel optical elements and to avoid some drawbacks of BFL properties related to aspect-ratio dependent etching.

  9. Gravitational Lensing

    SciTech Connect

    Lincoln, Don

    2015-06-24

    In a long line of intellectual triumphs, Einstein’s theory of general relativity was his greatest and most imaginative. It tells us that what we experience as gravity can be most accurately described as the bending of space itself. This idea leads to consequences, including gravitational lensing, which is caused by light traveling in this curved space. This is works in a way analogous to a lens (and hence the name). In this video, Fermilab’s Dr. Don Lincoln explains a little general relativity, a little gravitational lensing, and tells us how this phenomenon allows us to map out the matter of the entire universe, including the otherwise-invisible dark matter.

  10. Gravitational Lensing

    ScienceCinema

    Lincoln, Don

    2016-07-12

    In a long line of intellectual triumphs, Einstein’s theory of general relativity was his greatest and most imaginative. It tells us that what we experience as gravity can be most accurately described as the bending of space itself. This idea leads to consequences, including gravitational lensing, which is caused by light traveling in this curved space. This is works in a way analogous to a lens (and hence the name). In this video, Fermilab’s Dr. Don Lincoln explains a little general relativity, a little gravitational lensing, and tells us how this phenomenon allows us to map out the matter of the entire universe, including the otherwise-invisible dark matter.

  11. Fabrication techniques for very fast diffractive lenses

    NASA Technical Reports Server (NTRS)

    Tai, Anthony M.; Marron, Joseph C.

    1993-01-01

    Aspheric lenses with arbitrary phase functions can be fabricated on thin light weight substrates via the binary optics fabrication technique. However, it is difficult and costly to fabricate a fast lens (f/number less than 1) for use as the shorter wavelengths. The pitch of the masks and the alignment accuracy must be very fine. For a large lens, the space-bandwidth product of the element can also become impractically large. In this paper, two alternate approaches for the fabrication of fast aspheric diffractive lenses are described. The first approach fabricates the diffractive lens interferometrically, utilizing a spherical wavefront to provide the optical power of the lens and a computer generated hologram to create the aspheric components. The second approach fabricates the aspheric diffractive lens in the form if a higher order kinoform which trades groove profile fidelity for coarser feature size. The design and implementation issues for these two fabrication techniques are discussed.

  12. High strength, light weight Ti-Y composites and method of making same

    DOEpatents

    Verhoeven, J.D.; Ellis, T.W.; Russell, A.M.; Jones, L.L.

    1993-04-06

    A high strength, light weight in-situ'' Ti-Y composite is produced by deformation processing a cast body having Ti and Y phase components distributed therein. The composite comprises elongated, ribbon-shaped Ti and Y phase components aligned along an axis of the deformed body.

  13. High strength, light weight Ti-Y composites and method of making same

    DOEpatents

    Verhoeven, John D.; Ellis, Timothy W.; Russell, Alan M.; Jones, Lawrence L.

    1993-04-06

    A high strength, light weight "in-situ" Ti-Y composite is produced by deformation processing a cast body having Ti and Y phase components distributed therein. The composite comprises elongated, ribbon-shaped Ti and Y phase components aligned along an axis of the deformed body.

  14. Generalized prism-array lenses for hard X-rays.

    PubMed

    Cederström, Björn; Ribbing, Carolina; Lundqvist, Mats

    2005-05-01

    A Fresnel-like X-ray lens can be constructed by a triangular array of identical prisms whose base corresponds to the 2pi-shift length. Each column of prisms is progressively shifted from the optical axis by an arbitrary fraction of the prism height. Similarly to the multi-prism lens, quasi-parabolic profiles are formed by a superposition of straight-line segments. The resulting projected lens profile is approximately linear with a Fresnel-lens pattern superimposed on it to provide the focusing. This geometry exhibits a significantly larger effective aperture than conventional parabolic refractive lenses. Prototype lenses were fabricated by deep reactive ion etching of silicon. These one-dimensionally focusing lenses were tested at a synchrotron beamline and provided focal line-widths down to 1.4 microm FWHM and an intensity gain of 39 at a photon energy of 13.4 keV. Fabrication imperfections gave rise to unwanted interference effects resulting in several intensity maxima in the focal plane. The presented design allows the focal length to be shortened without decreasing the feature size of the lens. Furthermore, this feature size does not limit the resolution as for real Fresnel optics.

  15. Fresnel Interferometric Imager: ground-based prototype.

    PubMed

    Serre, Denis; Deba, Paul; Koechlin, Laurent

    2009-05-20

    The Fresnel Interferometric Imager is a space-based astronomical telescope project yielding milli-arcsecond angular resolution and high contrast images with loose manufacturing constraints. This optical concept involves diffractive focusing and formation flying: a first "primary optics" space module holds a large binary Fresnel array, and a second "focal module" holds optical elements and focal instruments that allow for chromatic dispersion correction. We have designed a reduced-size Fresnel Interferometric Imager prototype and made optical tests in our laboratory in order to validate the concept for future space missions. The primary module of this prototype consists of a square, 8 cm side, 23 m focal length Fresnel array. The focal module is composed of a diaphragmed small telescope used as "field lens," a small cophased diverging Fresnel zone lens that cancels the dispersion, and a detector. An additional module collimates the artificial targets of various shapes, sizes, and dynamic ranges to be imaged. We describe the experimental setup, different designs of the primary Fresnel array, and the cophased Fresnel zone lens that achieves rigorous chromatic correction. We give quantitative measurements of the diffraction limited performances and dynamic range on double sources. The tests have been performed in the visible domain, lambda = 400-700 nm. In addition, we present computer simulations of the prototype optics based on Fresnel propagation that corroborate the optical tests. This numerical tool has been used to simulate the large aperture Fresnel arrays that could be sent to space with diameters of 3 to 30 m, foreseen to operate from Lyman alpha (121 nm) to mid IR (25 microm).

  16. Ultralightweight Fresnel Lens Solar Concentrators for Space Power

    NASA Technical Reports Server (NTRS)

    ONeill, M. J.; McDanal, A. J.

    2000-01-01

    The first phase of this project was completed in March 2000, and included the successful technology demonstration of a new ultralightweight photovoltaic concentrator array at the fully functional panel level. The new array is called the Stretched Lens Aurora (SLA) array, and uses deployable, flexible, thin-film silicone rubber Fresnel lenses to focus sunlight onto high efficiency multijunction solar cells, which are mounted to a composite radiator surface for waste heat dissipation. A prototype panel was delivered to NASA Marshall in March 2000, and comprised four side-by-side lenses focussing sunlight onto four side-by-side photovoltaic receivers. This prototype panel was tested by NASA Glenn prior to delivery to NASA Marshall. The best of the four lens/receiver modules achieved 27.4% efficiency at room temperature in the NASA Glenn solar simulator tests. This performance equates to 375 W/sq.m. areal power and 378 W/kg specific power at the fully functional panel level. We believe this to be the first space solar array of any kind to simulataneously meet the two long-standing NASA goals of 300 W/sq.m. and 300 W/kg at the functional panel level. Key results for the first phase of the program have been documented by ENTECH in a Draft Final Technical Report, which is presently being reviewed by NASA, and which should be published in the near future.

  17. Twenty Meter Space Telescope Based on Diffractive Fresnel Lens

    SciTech Connect

    Early, J; Hyde, R; Baron, R

    2003-06-26

    Diffractive lenses offer two potential advantages for very large aperture space telescopes; very loose surface-figure tolerances and physical implementation as thin, flat optical elements. In order to actually realize these advantages one must be able to build large diffractive lenses with adequate optical precision and also to compactly stow the lens for launch and then fully deploy it in space. We will discuss the recent fabrication and assembly demonstration of a 5m glass diffractive Fresnel lens at LLNL. Optical performance data from smaller full telescopes with diffractive lens and corrective optics show diffraction limited performance with broad bandwidths. A systems design for a 20m space telescope will be presented. The primary optic can be rolled to fit inside of the standard fairings of the Delta IV vehicle. This configuration has a simple deployment and requires no orbital assembly. A twenty meter visible telescope could have a significant impact in conventional astronomy with eight times the resolution of Hubble and over sixty times the light gathering capacity. If the light scattering is made acceptable, this telescope could also be used in the search for terrestrial planets.

  18. High refractive index Fresnel lens on a fiber fabricated by nanoimprint lithography for immersion applications

    NASA Astrophysics Data System (ADS)

    Koshelev, Alexander; Calafiore, Giuseppe; Piña-Hernandez, Carlos; Allen, Frances I.; Dhuey, Scott; Sassolini, Simone; Wong, Edward; Lum, Paul; Munechika, Keiko; Cabrini, Stefano

    2016-08-01

    In this Letter we present a Fresnel lens fabricated on the end of an optical fiber. The lens is fabricated using nanoimprint lithography of a functional high refractive index material, which is suitable for mass production. The main advantage of the presented Fresnel lens compared to a conventional fiber lens is its high refractive index (n=1.69), which enables efficient light focusing even inside other media such as water or adhesive. Measurement of the lens performance in an immersion liquid (n=1.51) shows a near diffraction limited focal spot of 810 nm in diameter at the 1/e2 intensity level for a wavelength of 660 nm. Applications of such fiber lenses include integrated optics, optical trapping and fiber probes.

  19. Anti-soiling coating based on silica for Fresnel lens of concentrator photovoltaics

    NASA Astrophysics Data System (ADS)

    Hirohata, Takuya; Ota, Yasuyuki; Nishioka, Kensuke

    2015-08-01

    A simple anti-soiling layer was coated on the surface of poly(methyl methacrylate), which is the primary material of Fresnel lenses for concentrator photovoltaics. The main material of the anti-soiling layer was silica and the layer contained abundant hydroxyl groups that adsorbed water on the surface. After 9 months of exposure, the transmittance of the sample without the coating was 83.9%. On the other hand, the transmittance of the sample with the coating was 90.7%. The relationship between the electrostatic potential and the adhesion of sand on a Fresnel lens was evaluated. The electrostatic potential and mass of the adherent sand were decreased by the anti-soiling coating.

  20. High refractive index Fresnel lens on a fiber fabricated by nanoimprint lithography for immersion applications.

    PubMed

    Koshelev, Alexander; Calafiore, Giuseppe; Piña-Hernandez, Carlos; Allen, Frances I; Dhuey, Scott; Sassolini, Simone; Wong, Edward; Lum, Paul; Munechika, Keiko; Cabrini, Stefano

    2016-08-01

    In this Letter, we present a Fresnel lens fabricated on the end of an optical fiber. The lens is fabricated using nanoimprint lithography of a functional high refractive index material, which is suitable for mass production. The main advantage of the presented Fresnel lens compared to a conventional fiber lens is its high refractive index (n=1.68), which enables efficient light focusing even inside other media, such as water or an adhesive. Measurement of the lens performance in an immersion liquid (n=1.51) shows a near diffraction limited focal spot of 810 nm in diameter at the 1/e2 intensity level for a wavelength of 660 nm. Applications of such fiber lenses include integrated optics, optical trapping, and fiber probes.

  1. Phakic Intraocular Lenses

    MedlinePlus

    ... Implants and Prosthetics Phakic Intraocular Lenses Phakic Intraocular Lenses Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Phakic intraocular lenses are new devices used to correct nearsightedness. These ...

  2. Fabrication of Fresnel micro lens array in borosilicate glass by F2-laser ablation for glass interposer application

    NASA Astrophysics Data System (ADS)

    Brusberg, Lars; Neitz, Marcel; Schröder, Henning; Fricke-Begemann, Thomas; Ihlemann, Jürgen

    2014-03-01

    The future need for more bandwidth forces the development of optical transmission solutions for rack-to-rack, boardto- board and chip-to-chip interconnects. The goals are significant reduction of power consumption, highest density and potential for bandwidth scalability to overcome the limitations of the systems today with mostly copper based interconnects. For system integration the enabling of thin glass as a substrate material for electro-optical components with integrated micro-optics for efficient light coupling to integrated optical waveguides or fibers is becoming important. Our glass based packaging approach merges micro-system packaging and glass integrated optics. This kind of packaging consists of a thin glass substrate with integrated micro lenses providing a platform for photonic component assembly and optical fiber or waveguide interconnection. Thin glass is commercially available in panel and wafer size and characterizes excellent optical and high frequency properties. That makes it perfect for microsystem packaging. A suitable micro lens approach has to be comparable with different commercial glasses and withstand post-processing like soldering. A benefit of using laser ablated Fresnel lenses is the planar integration capability in the substrate for highest integration density. In the paper we introduce our glass based packaging concept and the Fresnel lens design for different scenarios like chip-to-fiber, chip-to-optical-printed-circuit-board coupling. Based on the design the Fresnel lenses were fabricated by using a 157 nm fluorine laser ablation system.

  3. Contact Lenses for Vision Correction

    MedlinePlus

    ... Ophthalmologist Patient Stories Español Eye Health / Glasses & Contacts Contact Lenses Sections Contact Lenses for Vision Correction Proper ... to Know About Contact Lenses Colored Contact Lenses Contact Lenses for Vision Correction Written by: Kierstan Boyd ...

  4. Compound Refractive Lenses for Thermal Neutron Applications

    SciTech Connect

    Gary, Charles K.

    2013-11-12

    This project designed and built compound refractive lenses (CRLs) that are able to focus, collimate and image using thermal neutrons. Neutrons are difficult to manipulate compared to visible light or even x rays; however, CRLs can provide a powerful tool for focusing, collimating and imaging neutrons. Previous neutron CRLs were limited to long focal lengths, small fields of view and poor resolution due to the materials available and manufacturing techniques. By demonstrating a fabrication method that can produce accurate, small features, we have already dramatically improved the focal length of thermal neutron CRLs, and the manufacture of Fresnel lens CRLs that greatly increases the collection area, and thus efficiency, of neutron CRLs. Unlike a single lens, a compound lens is a row of N lenslets that combine to produce an N-fold increase in the refraction of neutrons. While CRLs can be made from a variety of materials, we have chosen to mold Teflon lenses. Teflon has excellent neutron refraction, yet can be molded into nearly arbitrary shapes. We designed, fabricated and tested Teflon CRLs for neutrons. We demonstrated imaging at wavelengths as short as 1.26 ? with large fields of view and achieved resolution finer than 250 μm which is better than has been previously shown. We have also determined designs for Fresnel CRLs that will greatly improve performance.

  5. Multidimensional imaging using compressive Fresnel holography.

    PubMed

    Horisaki, Ryoichi; Tanida, Jun; Stern, Adrian; Javidi, Bahram

    2012-06-01

    We propose a generalized framework for single-shot acquisition of multidimensional objects using compressive Fresnel holography. A multidimensional object with spatial, spectral, and polarimetric information is propagated with the Fresnel diffraction, and the propagated signal of each channel is observed by an image sensor with randomly arranged optical elements for filtering. The object data are reconstructed using a compressive sensing algorithm. This scheme is verified with numerical experiments. The proposed framework can be applied to imageries for spectrum, polarization, and so on.

  6. Optimization of modified volume Fresnel zone plates.

    PubMed

    Srisungsitthisunti, Pornsak; Ersoy, Okan K; Xu, Xianfan

    2009-10-01

    Modified volume Fresnel zone plates (MVFZPs) fabricated with laser direct writing were optimized for higher diffraction efficiencies. The Fresnel radii in each layer of a volume zone plate were iteratively adjusted by a simulation-based direct search optimization. The results show that optimization is effective but depends strongly on the starting diffraction efficiencies determined by the MVFZP parameters. The simulations indicate that the optimized MVFZP can achieve 93% diffraction efficiency.

  7. Development and evaluation of an improved efficiency polymeric web point-focus Fresnel lens

    SciTech Connect

    Cobb, S. Jr.

    1987-04-01

    The feasibility of producing parquets of point-focus Fresnel lenses with a 2/sup 0/ draft angle on the riser in a continuous polymeric web is described. The parquet produced consisted of 14 square lenses, each 8.16 in. on a side, in a 2 by 7 format. The primary aim was to show that an increased efficiency was possible over that reported in SAND83-7023 by decreasing the draft angle. A secondary aim was also to produce a web of sufficient thickness to be used without lamination to a thick superstrate. The results demonstrated that increased efficiency was realized for both the thin and thick caliper material, with performance nearly equal to a direct-cut control lens. The results also show that a bowing or sagging problem exists in the laminated lenses. They also show that the thicker, non-laminated lenses may not be stiff enough to lie flat and may buckle, causing these lenses to be potentially unacceptable.

  8. Irradiance tailoring with two-sided Fresnel-type freeform optics

    NASA Astrophysics Data System (ADS)

    Bruneton, Adrien; Bäuerle, Axel; Traub, Martin; Wester, Rolf; Loosen, Peter

    2012-10-01

    Based on the Monge-Kantorovich theory of optimal mass transport, the computation of a ray mapping between source and target irradiances is used to design two-sided freeform lenses fulfilling the constraints of an automotive application: compactness and sharp bright-dark cutoff. A generic segmentation technic resulting in Fresnel-type optics is presented and the whole procedure is illustrated with the design of a fog light lens. Finally Monte Carlo simulation of the virtual model and measurements of a polycarbonate prototype are presented.

  9. Design and development of a laminated Fresnel lens for point-focus PV systems. Phase II

    SciTech Connect

    Hodge, R.C.

    1982-12-01

    A laminated glass-plastic lens parquet using injection molded point focus Fresnel lenses is described. The second phase of a program aimed at investigating the cost effectiveness of a glass-plastic concentrator lens assembly is reported. The first phase dealt with the development of a first generation lens design, the selection of the preferred glass coverplate and glass-to-lens adhesive and initial injection molding lens molding trials. The second phase has dealt with the development of an improved lens design, a full size parquet lamination process, and a second group of injection molding lens molding trials.

  10. Demonstration of 12 nm resolution Fresnel zone plate lens based soft x-ray microscopy

    SciTech Connect

    Chao, W.; Kim, J.; Rekawa, S.; Fischer, P.; Anderson, E. H.

    2009-06-05

    To extend soft x-ray microscopy to a resolution of order 10 nm or better, we developed a new nanofabrication process for Fresnel zone plate lenses. The new process, based on the double patterning technique, has enabled us to fabricate high quality gold zone plates with 12 nm outer zones. Testing of the zone plate with the full-field transmission x-ray microscope, XM-1, in Berkeley, showed that the lens clearly resolved 12 nm lines and spaces. This result represents a significant step towards 10 nm resolution and beyond.

  11. Optimal design of inverted truncated pyramid with Fresnel lens for concentrated photovoltaic Units

    NASA Astrophysics Data System (ADS)

    El-Yahyaoui, S.; El Himer, S.; Mechaqrane, A.; Ahaitouf, A.

    2017-03-01

    The aim of the presented work was to determine the optimum parameters of inverter truncated rectangular pyramid with Fresnel lenses. The use of secondary optical element (SOE) in a concentrated photovoltaic system can be effective in redirecting the sun light into the solar cell, increasing the concentration as well as improving the energy uniformity on the solar cell Ray tracing technique was used to simulate the optical characteristics of the CPV unit with various design parameters of the component. Finally, a typical concentrator was designed by using three possible materials, the Fused Silica, the BK7 and the PMMA.

  12. Realization of a time-domain Fresnel lens with coherent control.

    PubMed

    Degert, Jérôme; Wohlleben, Wendel; Chatel, Béatrice; Motzkus, Marcus; Girard, Bertrand

    2002-11-11

    Perturbative chirped pulse excitation leads to oscillations of the excited state amplitude. These coherent transients are governed by interferences between resonant and off-resonant contributions. Control mechanisms in both frequency and time domain are used to modify these dynamics. First, by applying a phase step in the spectrum, we manipulate the phase of the oscillations. By direct analogy with Fresnel zone lenses, we then conceive highly phase-amplitude modulated pulse shapes that slice destructive interferences out of the excitation time structure and enhance the final population.

  13. SCARLET: Design of the Fresnel concentrator array for New Millennium Deep Space 1

    SciTech Connect

    Murphy, D.M.; Eskenazi, M.I.

    1997-12-31

    The primary power for the JPL New Millennium Deep Space 1 spacecraft is a 2.6 kW concentrator solar array. This paper surveys the design and analysis employed to combine line-focus Fresnel lenses and multijunction (GaInP{sub 2}/GaAs/Ge) solar cells in the second-generation SCARLET (Solar Concentrator Array with Refractive Linear Element Technology) system. The array structure and mechanisms are reviewed. Discussion is focused on the lens and receiver, from the optimizations of optical efficiency and thermal management, to the design issues of environmental extremes, reliability, producibility, and control of pointing error.

  14. GLIDE: a grid-based light-weight infrastructure for data-intensive environments

    NASA Technical Reports Server (NTRS)

    Mattmann, Chris A.; Malek, Sam; Beckman, Nels; Mikic-Rakic, Marija; Medvidovic, Nenad; Chrichton, Daniel J.

    2005-01-01

    The promise of the grid is that it will enable public access and sharing of immense amounts of computational and data resources among dynamic coalitions of individuals and institutions. However, the current grid solutions make several limiting assumptions that curtail their widespread adoption. To address these limitations, we present GLIDE, a prototype light-weight, data-intensive middleware infrastructure that enables access to the robust data and computational power of the grid on DREAM platforms.

  15. Glasses and Contact Lenses

    MedlinePlus

    ... dientes Video: Getting an X-ray Glasses and Contact Lenses KidsHealth > For Kids > Glasses and Contact Lenses Print A A A What's in this ... together the way they should. But eyeglasses or contact lenses, also called corrective lenses, can help most ...

  16. Gravitational lenses

    SciTech Connect

    Turner, E.L.

    1988-07-01

    For several years astronomers have devoted considerable effort to finding and studying a class of celestial phenomena whose very existence depends on rare cosmic accidents. These are gravitational-lens events, which occur when two or more objects at different distances from the earth happen to lie along the same line of sight and so coincide in the sky. The radiation from the more distant object, typically a quasar, is bent by the gravitational field of the foreground object. The bending creates a cosmic mirage: distorted or multiple images of the background object. Such phenomena may reveal many otherwise undetectable features of the image source, of the foreground object and of the space lying between them. Such observations could help to resolve several fundamental questions in cosmology. In the past decade theoretical and observational research on gravitational lenses has grown rapidly and steadily. At this writing at least 17 candidate lens systems have been discussed in the literature. Of the 17 lens candidates reported so far in professional literature, only five are considered to have been reliably established by subsequent observations. Another three are generally regarded as weak or speculative cases with less than 50 percent chance of actually being lens systems. In the remaining nine cases the evidence is mixed or is sparse enough so that the final judgment could swing either way. As might be concluded, little of the scientific promise of gravitational lenses has yet been realized. The work has not yielded a clear value for the proportionality constant or any of the other fundamental cosmological parameter. 7 figs.

  17. Fresnel diffraction at an opaque strip expressed by means of asymptotic representations of Fresnel integrals.

    PubMed

    Šmíd, Petr; Horváth, Pavel

    2012-06-01

    The paper presents an asymptotic expression of relative intensity distribution in a Fresnel diffraction pattern at an opaque straight strip illuminated with a spherical wave. The asymptotic expression is used in an analysis showing an area of validity where the asymptotic expression reduces to an asymptotic expression of relative intensity distribution in a Fresnel diffraction at a half plane. The area of validity is defined through width of the geometrical shadow in a Fresnel diffraction pattern at an opaque straight strip and distance of a point under study to the center of the Fresnel diffraction pattern. Within this area, relative intensity in the Fresnel diffraction pattern at an opaque straight strip shows sinusoidal behavior, which can be used in easy location of maxima or minima of the relative intensity. The result of the analysis is supported by experiments realized in the area of validity and outside it.

  18. Huygens-Fresnel wavefront tracing

    NASA Astrophysics Data System (ADS)

    Volpe, F. A.; Létourneau, P.-D.; Zhao, A.

    2017-03-01

    We present initial results from a novel numerical method describing wave propagation in slowly non-uniform media. Following Huygens-Fresnel's principle, we model the wavefront as an array of point sources that emit wavelets, which interfere. We then identify a set of new points where the electric field has equal phase. In fact, without losing generality, we find zeros of the electric field, by means of the bisection method. This obviously corresponds to a specific phase-advance, but is easily generalized, e.g. by phase-shifting all sources. The points found form the new wavefront, then the process is reiterated. One of the advantages of the method is that it includes diffraction. Two examples provided are diffraction around an obstacle and the finite waist of a focused Gaussian beam. Refraction is also successfully modeled, both in slowly-varying media as well as in the presence of discontinuities. The calculations were performed in two dimensions, but can be easily extended to three dimensions. We also discuss the extension to anisotropic, birefringent, absorbing media.

  19. Fresnel lens solar concentrator design based on geometric optics and blackbody radiation equations

    SciTech Connect

    Watson, M.D.; Jayroe, R.R. Jr.

    1999-07-01

    Fresnel lenses have been used for years as solar concentrators in a variety of applications. Several variables affect the final design of these lenses including: lens diameter, image spot distance from the lens, and bandwidth focused in the image spot. Defining the image spot as the geometrical optics circle of least confusion, a set of design equations has been derived to define the groove angles for each groove on the lens. These equations allow the distribution of light by wavelength within the image spot to be calculated. Combining these equations with the blackbody radiation equations power, power distribution, and flux within the image spot can be calculated. In addition, equations have been derived to design a lens to produce maximum flux in a given spot size. Using these equations, a lens may be designed to optimize the spot energy concentration for given energy source.

  20. Fresnel Lens Solar Concentrator Design Based on Geometric Optics and Blackbody Radiation Equations

    NASA Technical Reports Server (NTRS)

    Watson, Michael D.; Jayroe, Robert

    1998-01-01

    Fresnel lenses have been used for years as solar concentrators in a variety of applications. Several variables effect the final design of these lenses including: lens diameter, image spot distance from the lens, and bandwidth focused in the image spot. Defining the image spot as the geometrical optics circle of least confusion, a set of design equations has been derived to define the groove angles for each groove on the lens. These equations allow the distribution of light by wavelength within the image spot to be calculated. Combining these equations with the blackbody radiation equations, energy distribution, power, and flux within the image spot can be calculated. In addition, equations have been derived to design a lens to produce maximum flux in a given spot size. Using these equations, a lens may be designed to optimize the spot energy concentration for given energy source.

  1. Fresnel Lens Scatter Plate for Data Reduction Holography.

    DTIC Science & Technology

    In the patent the holographic apparatus and method uses a Fresnel lens as a scatter plate in data reduction holography. A second embodiment uses a Fresnel lens in series with a fly’s eye lens array.

  2. Roll-to-roll embossing of optical linear Fresnel lens polymer film for solar concentration.

    PubMed

    Zhang, XinQuan; Liu, Kui; Shan, Xuechuan; Liu, Yuchan

    2014-12-15

    Roll-to-roll manufacturing has been proven to be a high-throughput and low-cost technology for continuous fabrication of functional optical polymer films. In this paper, we have firstly studied a complete manufacturing cycle of linear Fresnel lens polymer film for solar concentration in the aspects of ultra-precision diamond machining of metal roller mold, roll-to-roll embossing, and measurement on film profile and functionality. A metal roller mold patterned with linear Fresnel lenses is obtained using single point diamond turning technique. The roller mold is installed onto a self-developed roll-to-roll UV embossing system to realize continuous manufacturing of linear Fresnel lens film. Profile measurement of the machined roller mold and the embossed polymer film, which is conducted using a stylus profilometer, shows good agreement between measured facet angles with designed ones. Functionality test is conducted on a solar simulation system with a reference solar cell, and results show that strong light concentration is realized.

  3. A small and light weight heat exchanger for on-board helium refrigerator

    NASA Technical Reports Server (NTRS)

    Koizumi, T.; Takahashi, M.; Uchida, T.; Kanazawa, Y.; Suzuki, M.

    1983-01-01

    A small and light weight heat exchanger used for small helium refrigerator has been developed by Sumitomo Heavy Industries, Ltd. This heat exchanger is a laminated metal heat exchanger which consists of perforated aluminum metal plates and glassfiber reinforced plastic separators. The size is from 100 mm to 28 mm in diameter and about 300 mm in length. The weight is from 2.5 kg to 0.6 kg. Also it can be used between room temperature and liquid helium temperature. The thermal efficiency obtained has been more than 96%. The heat exchanger has been practically used for on-board helium refrigerator in Japanese National Railways' superconducting magnetic levitated trains.

  4. Unique Concept for a Low Cost, Light Weight Space Deployable Antenna Structure

    NASA Technical Reports Server (NTRS)

    Freeland, Robert E.; Bilyeu, Gayle D.; Veal, Gordon R.

    1993-01-01

    Large space deployable antennas are needed for a variety of applications that include Mobile Communications, Radiometry, Active Microwave Sensing, Very Long Baseline Interferometry and DoD Space Based Radar. These user requirements identify the need for structures up to tens of meters in size for operation from 1 to 90 GHz, based on different aperture configurations. However, the one thing the users have in common is a concept selection criteria for low cost, light weight and highly reliable deployable structures. Fortunately, a unique class of space structures has recently emerged that have tremendous potential for satisfying these criteria. They are referred to as inflatable deployable structures.

  5. 21 CFR 886.1655 - Ophthalmic Fresnel prism.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ophthalmic Fresnel prism. 886.1655 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1655 Ophthalmic Fresnel prism. (a) Identification. An ophthalmic Fresnel prism is a device that is a thin plastic sheet with embossed rulings...

  6. 21 CFR 886.1655 - Ophthalmic Fresnel prism.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ophthalmic Fresnel prism. 886.1655 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1655 Ophthalmic Fresnel prism. (a) Identification. An ophthalmic Fresnel prism is a device that is a thin plastic sheet with embossed rulings...

  7. 21 CFR 886.1655 - Ophthalmic Fresnel prism.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic Fresnel prism. 886.1655 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1655 Ophthalmic Fresnel prism. (a) Identification. An ophthalmic Fresnel prism is a device that is a thin plastic sheet with embossed rulings...

  8. 21 CFR 886.1390 - Flexible diagnostic Fresnel lens.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Flexible diagnostic Fresnel lens. 886.1390 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1390 Flexible diagnostic Fresnel lens. (a) Identification. A flexible diagnostic Fresnel lens is a device that is a very thin lens which...

  9. 21 CFR 886.1390 - Flexible diagnostic Fresnel lens.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Flexible diagnostic Fresnel lens. 886.1390 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1390 Flexible diagnostic Fresnel lens. (a) Identification. A flexible diagnostic Fresnel lens is a device that is a very thin lens which...

  10. 21 CFR 886.1390 - Flexible diagnostic Fresnel lens.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Flexible diagnostic Fresnel lens. 886.1390 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1390 Flexible diagnostic Fresnel lens. (a) Identification. A flexible diagnostic Fresnel lens is a device that is a very thin lens which...

  11. 21 CFR 886.1390 - Flexible diagnostic Fresnel lens.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Flexible diagnostic Fresnel lens. 886.1390 Section... (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1390 Flexible diagnostic Fresnel lens. (a) Identification. A flexible diagnostic Fresnel lens is a device that is a very thin lens which...

  12. Polarization Compensation of Fresnel Aberrations in Telescopes

    NASA Technical Reports Server (NTRS)

    Clark, Natalie; Breckenridge, James B.

    2011-01-01

    Large aperture space telescopes are built with low F# s to accommodate the mechanical constraints of launch vehicles and to reduce resonance frequencies of the on-orbit system. Inherent with these low F# s is Fresnel polarization which affects image quality. We present the design and modeling of a nano-structure consisting of birefringent layers to control polarization and increase contrast. Analysis shows a device that functions across a 400nm bandwidth tunable from 300nm to 1200nm. This Fresnel compensator device has a cross leakage of less than 0.001 retardance.

  13. Light Weight UAVs for Unravelling the Nexus Between Chemistry, Physics and Dynamics

    NASA Astrophysics Data System (ADS)

    Ramanathan, V.

    2015-12-01

    New discoveries in atmospheric sciences involve unravelling the interactions and feedback processes between chemitsry, physics and dynamics. One of the most complex of such problems is the role of aerosol-clouds-climate interactions in climate change. During the last 7 years we have designed field experiments with light weight UAVs that are flown in stacked as well as formation flying patterns to map out the three dimensional structure of the atmosphere. Such formation and stacked formation flights have enabled us to measure simulatneously aerosol chemistry, cloud micro physics, cloud albedo, divergence of radiative heating of the atmosphere and more recently the vertical structure of turbulent fluxes of water avpor and momentum. These first-such measurments have provided new insights into the role of aerosols in cloud albedo; vertical distribution of black and brown carbon heating; role of absorbing aerosols in the melting of Himalayan glaciers; role of mixing state of aerosols in aerosol forcing and recently the link between absorbing aerosols and turbulent fluxes. All of the instruments had to be miniaturized to fit into the UAVs with maximum of 6 kg of payload. The most impprtant aspects of our studies are that the instruments and their intergration with the UAvs were all developed by post doctoral candidates and students. Thus the light weight UAVs are ideal platforms for making pioneerign studies by students and young scientists.

  14. Co/graphite based light weight microwave absorber for electromagnetic shielding and stealth applications

    NASA Astrophysics Data System (ADS)

    Ansari, Azizurrahaman; Jaleel Akhtar, Mohammad

    2017-01-01

    The magnetic, thermal, thermo-mechanical, electromagnetic and microwave absorption properties of Co/graphite loaded polystyrene composites prepared by melt blending and injection molding techniques are studied in X-band (8.4–12.4 GHz) for seeking their usage as efficient light weight microwave absorbers. For profound understanding of electromagnetic absorption process at micro level, the advanced SEM and x-ray diffraction testing of the composites are carried out. The magnetic properties of the prepared Co/graphite loaded polystyrene composites are studied using the vibrating sample magnetometer. The thermal stability and thermo-mechanical properties of the prepared composites are analyzed by thermo gravimetric analysis and dynamic mechanical and thermal analysis, respectively. The complex permittivity and permeability values of the prepared composite samples in X-band of microwave frequency are extracted from the scattering data recorded during the vector network analyzer measurements. The minimum reflection loss (maximum absorption loss) of  ‑32.02 dB (99.94%) is achieved at 10.13 GHz for Co/graphite loaded polystyrene composite with the excess loading of graphite flakes for sample thickness of 1.8 mm. High absorption loss, light weight and low thickness of the proposed multicomponent Co/graphite loaded polystyrene composites make them promising candidates for electromagnetic shielding and stealth applications.

  15. ZnS micro-Fresnel lens and its uses.

    PubMed

    Hosokawa, H; Yamashita, T

    1990-12-01

    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. Furthermore, higher resolution in electron-beam lithography is made possible by lens thickness reduction. The completely flat micro-Fresnel lens is a new device and improves integration performance. This lens can be applied to stacked planar optics devices for use in the construction of 3-D optical circuits.

  16. TOPICAL REVIEW Gravitational lensing

    NASA Astrophysics Data System (ADS)

    Bartelmann, Matthias

    2010-12-01

    Gravitational lensing has developed into one of the most powerful tools for the analysis of the dark universe. This review summarizes the theory of gravitational lensing, its main current applications and representative results achieved so far. It has two parts. In the first, starting from the equation of geodesic deviation, the equations of thin and extended gravitational lensing are derived. In the second, gravitational lensing by stars and planets, galaxies, galaxy clusters and large-scale structures is discussed and summarized.

  17. Flat liquid crystal diffractive lenses with variable focus and magnification

    NASA Astrophysics Data System (ADS)

    Valley, Pouria

    Non-mechanical variable lenses are important for creating compact imaging devices. Various methods employing dielectrically actuated lenses, membrane lenses, and liquid crystal lenses were previously proposed [1-4]. In This dissertation the design, fabrication, and characterization of innovative flat tunable-focus liquid crystal diffractive lenses (LCDL) are presented. LCDL employ binary Fresnel zone electrodes fabricated on Indium-Tin-Oxide using conventional micro-photolithography. The light phase can be adjusted by varying the effective refractive index of a nematic liquid crystal sandwiched between the electrodes and a reference substrate. Using a proper voltage distribution across various electrodes the focal length can be changed between several discrete values. Electrodes are shunted such that the correct phase retardation step sequence is achieved. If the number of 2pi zone boundaries is increased by a factor of m the focal length is changed from f to f/m based on the digitized Fresnel zone equation: f = rm2/2mlambda, where r m is mth zone radius, and lambda is the wavelength. The chromatic aberration of the diffractive lens is addressed and corrected by adding a variable fluidic lens. These LCDL operate at very low voltage levels (+/-2.5V ac input), exhibit fast switching times (20-150 ms), can have large apertures (>10 mm), and small form factor, and are robust and insensitive to vibrations, gravity, and capillary effects that limit membrane and dielectrically actuated lenses. Several tests were performed on the LCDL including diffraction efficiency measurement, switching dynamics, and hybrid imaging with a refractive lens. Negative focal lengths are achieved by adjusting the voltages across electrodes. Using these lenses in combination, magnification can be changed and zoom lenses can be formed. These characteristics make LCDL a good candidate for a variety of applications including auto-focus and zoom lenses in compact imaging devices such as camera

  18. Contact Lenses on Submarines

    DTIC Science & Technology

    2014-09-26

    NAVAL SUBMARINE MEDICAL RESEARCH LABORATORY SUBMARINE BASE, GROTON, CONN. REPORT NUMBER 1048 CONTACT LENSES ON SUBMARINES... CONTACT LENSES ON SUBMARINES by James F. Socks, CDR, MSC, USN NAVAL SUBMARINE MEDICAL RESEARCH LABORATORY REPORT NUMBER 1048 NAVAL MEDICAL RESEARCH...DRSCHLAB Approved for public release; distribution unlimited SUMMARY PAGE PROBLEM To determine the feasibility of wearing contact lenses aboard

  19. A Simple Experiment on Fresnel Diffraction

    ERIC Educational Resources Information Center

    Haskell, Richard E.

    1970-01-01

    Describes an experiment in which the Fresnel diffraction pattern of a single slit can be displayed directly on an oscilloscope. The experiment requires a minimum amount of equipment and space. Results of the experiment are presented and compared with theoretical calculations carried out by a digital computer. (LC)

  20. Fresnel diffraction plates are simple and inexpensive

    NASA Technical Reports Server (NTRS)

    Hoover, R. B.

    1967-01-01

    Fresnel plate demonstrates diffraction phenomena simply and inexpensively. A large number of identical diffracting apertures are made in random orientation on photographic film. When a small source of light is viewed through the plate, the diffraction pattern typical of the diffracting aperture is readily seen.

  1. Phase singularity in the diffracted field from Fresnel's double mirror

    NASA Astrophysics Data System (ADS)

    Aalipour, Rasoul; Taghi Tavassoly, M.

    2013-05-01

    It is shown that when a coherent beam of light illuminates a Fresnel's double mirror, Fresnel diffraction becomes appreciable. The subject fundamentally differs from interference. We calculate the diffracted field by applying Fresnel-Kirchhoff integral. We modified the common Fresnel's double mirror by imposing an initial height between the mirrors, as the height is chosen small enough so that the application of Fresnel's double mirror is maintained. We show by simulation and experiment that a phase singularity causes from the initial height and modifies the diffracted field from the Fresnel's double mirror. One can adjust the location of the line singularity by changing the angle between the mirrors. Also, the anomalous behavior of a polychromatic beam diffracted from the modified Fresnel's double mirror at the neighborhood of the line singularity, is investigated by simulation.

  2. Characterizing the hard x-ray diffraction properties of a GaAs linear Bragg-Fresnel lens

    SciTech Connect

    Li, Youli; Wong, Gerard C. L.; Case, Ryan; Safinya, Cyrus R.; Caine, Ernie; Hu, Evelyn; Fernandez, Partricia

    2000-07-17

    We investigated the diffractive focusing properties of (111) GaAs linear Bragg-Fresnel lenses (BFLs) developed for hard x-ray microscopy and microdiffraction of complex materials in confined geometries. We demonstrated that the use of GaAs yields significant processing advantages due to the reduced zone depth. Focal plane diffraction patterns of linear BFLs measured at the advanced photon source using 8-40 keV x rays were compared to a simple model based on Kirchhoff-Fresnel diffraction theory. Good agreement was obtained between experimental data and model calculations using only zones within an effective aperture defined by the transverse coherence of the source. (c) 2000 American Institute of Physics.

  3. Light-weight glass mirror systems for future x-ray telescopes

    NASA Astrophysics Data System (ADS)

    Winter, Anita; Breunig, Elias; Burwitz, Vadim; Friedrich, Peter; Hartner, Gisela; Menz, Benedikt; Proserpio, Laura

    2013-09-01

    Future X-ray telescopes need to combine large collecting area with good angular resolution. In order to achieve these aims within the mass limit, light-weight materials are needed for mirror production. We are developing a technology based on indirect hot slumping of thin glass segments; this method enables the production of the parabolic and hyperbolic part of the Wolter type I mirrors in one piece. Currently we use a combination of a porous ceramic for the slumping mould and the glass type D263 for the mirror material. In this study we use glasses that have been polished on one side to remove thickness variations in the glass, in order to investigate their influence on the results. We describe the experimental set-up, the slumping process and the metrology methods. Finally we present the results of an X-ray test of several integrated glass sheets, and give an outlook on future activities.

  4. Structural Design and Analysis of a Light-Weight Laminated Composite Heat Sink for Spaceflight PWBs

    NASA Technical Reports Server (NTRS)

    Fan, Mark S.; Niemeyer, W. Lee

    1997-01-01

    In order to reduce the overall weight in spaceborne electronic systems, a conventional metallic heat sink typically used for double-sided printed wiring boards was suggested to be replaced by light-weight and high-strength laminated composite materials. Through technology validation assurance (TVA) approach, it has been successfully demonstrated that using laminated composite heat sink can not only reduce the weight of the heat sink by nearly 50%, but also significantly lower the internal thermally-induced stresses that are largely responsible for potential delamination under cyclic temperature variations. With composite heat sink, both thermal and dynamic performance of the double-sided printed wiring board (PWB) exceeds that of its counterpart with metallic heat sink. Also included in this work is the original contribution to the understanding of creep behavior of the worst-case leadless chip carrier (LCC) surface mount solder joint. This was identified as the interconnection most susceptible to thermal fatigue damage in the PWB assembly.

  5. Metrology and Alignment of Light Weight Grazing Incidence X-Ray Mirrors

    NASA Technical Reports Server (NTRS)

    Zhang, William; Content, David; Petre, Robert; Saha, Timo

    2000-01-01

    Metrology and alignment of light weight X-ray optics have been a challenge for two reasons: (1) that the intrinsic mirror quality and distortions caused by handling can not be easily separated, and (2) the diffraction limits of the visible light become a severe problem at the order of one arc-minute. Traditional methods of using a normal incident pencil or small parallel beam which monitors a tiny fraction of the mirror in question at a given time can not adequately monitor those distortions. We are developing a normal incidence setup that monitors a large fraction, if not the whole, of the mirror at any given time. It will allow us to align thin X-ray mirrors to-an accuracy of a few arc seconds or to a limit dominated by the mirror intrinsic quality.

  6. A method and technique for installing light-weight fragile, high-temperature fiber insulation

    NASA Technical Reports Server (NTRS)

    Ballantine, T. J. (Inventor)

    1982-01-01

    A method of installing fragile, light-weight, high-temperature fiber insulation, particularly where the insulation is to be used as a seal strip providing a high order of thermal barrier insulation is described. The process is based on provision of a strip of the mineral batting cut oversize by a predetermined amount, saturated in a fugitive polymer solution, compressed in a mold, dried and cured to form a rigidized batting material which may be machined to required shape. The machined dimensions would normally be at least nominally less than the dimensions of the cavity to be sealed. After insertion in the cavity, which may be a wire-mesh seal enclosure, the apparatus is subjected to baking at a temperature sufficiently high to cause the resin to burn off cleanly, leaving the batting substantially in its original condition and expanded into the cavity or seal enclosure.

  7. Method and technique for installing light-weight, fragile, high-temperature fiber insulation

    NASA Technical Reports Server (NTRS)

    Patel, B. C. (Inventor)

    1983-01-01

    A method of installing fragile, light weight, high temperature fiber insulation, particularly where the insulation is to be used as a seal strip providing a high order of thermal barrier insulation is discussed. The process is based on provision of a strip of the mineral batting cut oversize by a predetermined amount, saturated in a fugitive polymer solution, compressed in a mold, dried and cured to form a rigidized batting material which is machined to required shape. The machine dimensions would normally be at least nominally less than the dimensions of the cavity to be sealed. After insertion in the cavity, which may be a wire-mesh seal enclosure, the apparatus is subjected to baking at a temperature sufficiently high to cause the resin to burn off cleanly, leaving the batting substantially in its original condition and expanded into the cavity or seal enclosure.

  8. Light-weight glass optics for segmented x-ray mirrors

    NASA Astrophysics Data System (ADS)

    Winter, Anita; Breunig, Elias; Capelli, Renzo; Friedrich, Peter; Burwitz, Vadim; Hartner, Gisela; Menz, Benedikt; Schmachtel, Tilman; Derst, Gerhard; Neher, Manfred

    2012-09-01

    One of the most challenging tasks for future X-ray observatories is the enhancement of collecting area combined with very good angular resolution. Light-weight mirror materials, such as thin glass sheets, are needed to achieve this aims within the mass limits. We are developing a technology based on indirect hot slumping of thin glass segments. This technique enables us to produce the parabolic and hyperbolic part of the Wolter type I mirrors in one piece. Currently we focus on a combination of a ceramic slumping mould and glass type D263. The experimental set-up in our laboratories as well as the slumping process are described in detail; furthermore we report on the metrology methods used for measuring the glass sheets and moulds. Finally the results of the X-ray tests of several integrated glass sheets are presented.

  9. Light weight radioisotope heater unit (LWRHU): a technical description of the reference design

    SciTech Connect

    Tate, R.E.

    1982-01-01

    The Light Weight Radioisotope Heater Unit (LWRHU), a new radioisotope heater unit for use in space missions, is a /sup 238/PuO/sub 2/-fueled unit designed to provide a thermal watt in dispersed locations on a spacecraft. The LWRHU is required to maintain the temperature of a component at a level where the component will function reliably in space. Two major constraints are placed on the unit's design; it must be as light as possible and must provide enough protection to immobilize the plutonium fuel to the maximum extent in all phases of the unit's lifetime. The four components are pelletized fuel, platinum-alloy encapsulation, pyrolytic graphite thermal insulation, and high-technology graphite ablation shell. The LWRHU is a cylinder 32 mm (1.26 in.) high and 26 mm (1.02 in.) in diameter. It weighs slightly less than 40 g(.09 lb).

  10. Elimination of flux loss by optimizing the groove angle in modified Fresnel lens to increase illuminance uniformity, color uniformity and flux efficiency in LED illumination.

    PubMed

    Kim, Byungwook; Choi, Minseok; Kim, Hokwan; Lim, Jiseok; Kang, Shinill

    2009-09-28

    A Fresnel lens is an optical component that can be used to create systems more compact, cost-effective, and lightweight than those using conventional continuous surface optics. However, Fresnel lenses can usually cause a loss of flux efficiency and non-uniform distribution of illuminance due to secondary refraction by surface discontinuities, especially along the groove facet. We therefore proposed to modify a groove angle in the Fresnel lens and analyzed interrelation between the groove angle and multiple optical performances, such as flux efficiency and the uniformity of illuminance and color. The groove angle was optimized to maximize the uniformity and efficiency in the target viewing angle considering various weights of merit functions. Specifically, in our study, when the uniformity of illuminance had a little more weight than the flux efficiency (ratio of 0.6:0.4), final optimum groove angles of 24.7 degrees , 29.4 degrees , and 31.3 degrees were obtained at target viewing angles of 20 degrees , 30 degrees , and 40 degrees , respectively. We also fabricated a modified Fresnel lens with a groove angle of 29.4 degrees using UV-imprinting. The real optical performance of the fabricated Fresnel lens was then compared to that of a spherical lens.

  11. Fresnel phasing of segmented mirror telescopes.

    PubMed

    Chanan, Gary; Troy, Mitchell; Surdej, Isabelle; Gutt, Gary; Roberts, Lewis C

    2011-11-20

    Shack-Hartmann (S-H) phasing of segmented telescopes is based upon a physical optics generalization of the geometrical optics Shack-Hartmann test, in which each S-H lenslet straddles an intersegment edge. For the extremely large segmented telescopes currently in the design stages, one is led naturally to very large pupil demagnifications for the S-H phasing cameras. This in turn implies rather small Fresnel numbers F for the lenslets; the nominal design for the Thirty Meter Telescope calls for F=0.6. For such small Fresnel numbers, it may be possible to eliminate the lenslets entirely, replacing them with a simple mask containing a sparse array of clear subapertures and thereby also eliminating a number of manufacturing problems and experimental complications associated with lenslets. We present laboratory results that demonstrate the validity of this approach.

  12. Fresnel lens analysis for solar applications

    SciTech Connect

    Lorenzo, E.; Luque, A.

    1981-09-01

    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 with a refractive-index approaching infinity and with a given profile turns out to be an ideal concentrator.

  13. Fresnel lens analysis for solar energy applications.

    PubMed

    Lorenzo, E; Luque, A

    1981-09-01

    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 with a refractive-index approaching infinity and with a given profile turns out to be an ideal concentrator.

  14. Numerical calculation of the Fresnel transform.

    PubMed

    Kelly, Damien P

    2014-04-01

    In this paper, we address the problem of calculating Fresnel diffraction integrals using a finite number of uniformly spaced samples. General and simple sampling rules of thumb are derived that allow the user to calculate the distribution for any propagation distance. It is shown how these rules can be extended to fast-Fourier-transform-based algorithms to increase calculation efficiency. A comparison with other theoretical approaches is made.

  15. Compressive Fresnel digital holography using Fresnelet based sparse representation

    NASA Astrophysics Data System (ADS)

    Ramachandran, Prakash; Alex, Zachariah C.; Nelleri, Anith

    2015-04-01

    Compressive sensing (CS) in digital holography requires only very less number of pixel level detections in hologram plane for accurate image reconstruction and this is achieved by exploiting the sparsity of the object wave. When the input object fields are non-sparse in spatial domain, CS demands a suitable sparsification method like wavelet decomposition. The Fresnelet, a suitable wavelet basis for processing Fresnel digital holograms is an efficient sparsifier for the complex Fresnel field obtained by the Fresnel transform of the object field and minimizes the mutual coherence between sensing and sparsifying matrices involved in CS. The paper demonstrates the merits of Fresnelet based sparsification in compressive digital Fresnel holography over conventional method of sparsifying the input object field. The phase shifting digital Fresnel holography (PSDH) is used to retrieve the complex Fresnel field for the chosen problem. The results are presented from a numerical experiment to show the proof of the concept.

  16. Ergonomic Evaluation of Space Shuttle Light-Weight Seat Lever Position and Operation

    NASA Technical Reports Server (NTRS)

    Maida, J.; Rajulu, Sudhakar L.; Bond, Robert L. (Technical Monitor)

    2000-01-01

    During a Shuttle flight in the early part of 1999, one of the crewmembers was unable to operate the backrest lever for the light-weight seat in microgravity. It is essential that the crewmembers are able to adjust this back-rest lever, which is titled forward 2 degrees from vertical during launch and then moved backwards to 10 degrees aft of vertical upon reaching orbit. This adjustment is needed to cushion the crewmembers during an inadvertent crash landing situation. The original Shuttle seats, which had seat controls located on the front left and right sides of the seat, were replaced recently with the new light-weight seats. The controls for these new, seats were moved to the night side with one control at the front and the other at the back. While it was uncertain whether the problem encountered was unique to that crewmember or not it was clear to the personnel responsible for maintaining the Shuttle seats that not knowing the cause of the problem posed a safety concern for NASA. Hence the Anthropometry and Biomechanics Facility (ABF) of the Johnson Space Center was requested to perform an evaluation of the seat controls and provide NASA with appropriate recommendations on whether the seat lever positions and operations should be modified. The ABF designed an experiment to investigate the amount of pull force exerted by subjects, wearing an unpressurized or pressurized crew launch escape suit, when controls were placed in the front and back (on the right side) of the light-weight seat. Single-axis load cells were attached to the seat levers, which measured the maximum static pull forces that were exerted by the subjects. Twelve subjects, six male and six female, participated in this study. Each subject was asked to perform the pull test at least three times for each combination of lever position and suit pressure conditions. The results from this study showed that as a whole (or in general), the subjects were able to pull on the lever at the back position with

  17. Solar powered desalination system using Fresnel lens

    NASA Astrophysics Data System (ADS)

    Sales, M. T. B. F.

    2016-11-01

    The Philippines is surrounded by coastal areas and these areas can be a potential source for potable water. This study aims to design and construct a solar powered desalination system using Fresnel lens. The experimental study was conducted using polluted salt water for the sample and desalination was carried out using the designed system. The desalination system was composed of the solar concentrator, solar still and the condenser system. The Fresnel lens was made of acrylic plastic and was an effective solar concentrator. Solar stills made of dark colored glass bottles were effective in absorbing the solar energy. The condenser system made of polybutylene and polystyrene were effective in condensing the vapor at ambient temperature. The shortest time of vaporization of the salt water was at 293 sec and the optimum angle of position of the lens was 36.42°. The amount of condensate collected was directly proportional to the amount of salt water in the solar still. The highest mean efficiency of the designed set-up was 34.82%. The water produced by the solar powered desalination system using Fresnel lens passed the standards set by WHO (World Health Organization) for drinking water.

  18. SUB 1-Millimeter Size Fresnel Micro Spectrometer

    NASA Technical Reports Server (NTRS)

    Park, Yeonjoon; Koch, Laura; Song, Kyo D.; Park, Sangloon; King, Glen; Choi, Sang

    2010-01-01

    An ultra-small micro spectrometer with less than 1mm diameter was constructed using Fresnel diffraction. The fabricated spectrometer has a diameter of 750 nmicrometers and a focal length of 2.4 mm at 533nm wavelength. The micro spectrometer was built with a simple negative zone plate that has an opaque center with an ecliptic shadow to remove the zero-order direct beam to the aperture slit. Unlike conventional approaches, the detailed optical calculation indicates that the ideal spectral resolution and resolving power do not depend on the miniaturized size but only on the total number of rings. We calculated 2D and 3D photon distribution around the aperture slit and confirmed that improved micro-spectrometers below 1mm size can be built with Fresnel diffraction. The comparison between mathematical simulation and measured data demonstrates the theoretical resolution, measured performance, misalignment effect, and improvement for the sub-1mm Fresnel micro-spectrometer. We suggest the utilization of an array of micro spectrometers for tunable multi-spectral imaging in the ultra violet range.

  19. Nonlinear Fresnel diffraction of weak shock waves.

    PubMed

    Coulouvrat, François; Marchiano, Régis

    2003-10-01

    Fresnel diffraction at a straight edge is revisited for nonlinear acoustics. Considering the penumbra region as a diffraction boundary layer governed by the KZ equation and its associated jump relations for shocks, similarity laws are established for the diffraction of a step shock, an "N" wave, or a periodic sawtooth wave. Compared to the linear case described by the well-known Fresnel functions, it is shown that weak shock waves penetrate more deeply into the shadow zone than linear waves. The thickness of the penumbra increases as a power of the propagation distance, power 1 for a step shock, or 3/4 for an N wave, as opposed to power 1/2 for a periodic sawtooth wave or a linear wave. This is explained considering the frequency spectrum of the waveform and its nonlinear evolution along the propagation, and is confirmed by direct numerical simulations of the KZ equation. New formulas for the Rayleigh/Fresnel distance in the case of nonlinear diffraction of weak shock waves by a large, finite aperture are deduced from the present study.

  20. Monitoring agricultural crops using a light-weight hyperspectral mapping system for unmanned aerial vehicles

    NASA Astrophysics Data System (ADS)

    Kooistra, Lammert; Suomalainen, Juha; Franke, Jappe; Bartholomeus, Harm; Mücher, Sander; Becker, Rolf

    2014-05-01

    Remote sensing has been identified as a key technology to allow near real-time detection and diagnosis of crop status at the field level. Although satellite based remote sensing techniques have already proven to be relevant for many requirements of crop inventory and monitoring, they might lack flexibility to support anomaly detection at specific moments over the growing season. Imagery taken from unmanned aerial vehicles (UAV) are shown to be an effective alternative platform for crop monitoring, given their potential of high spatial and temporal resolution, and their high flexibility in image acquisition programming. In addition, several studies have shown that an increased spectral resolution as available from hyperspectral systems provide the opportunity to estimate biophysical properties like leaf-area-index (LAI), chlorophyll and leaf water content with improved accuracies. To investigate the opportunities of unmanned aerial vehicles (UAV) in operational crop monitoring, we have developed a light-weight hyperspectral mapping system (< 2 kg) suitable to be mounted on small UAVs. Its composed of an octocopter UAV-platform with a pushbroom spectrometer consisting of a spectrograph, an industrial camera functioning as frame grabber, storage device, and computer, a separate INS and finally a photogrammetric camera. The system is able to produce georeferenced and georectified hyperspectral data cubes in the 400-1000 nm spectral range at 10-50 cm resolution. The system is tested in a fertilization experiment for a potato crop on a 12 ha experimental field in the South of the Netherlands. In the experiment UAV-based hyperspectral images were acquired on a weekly basis together with field data on chlorophyll as indicator for the nitrogen situation of the crop and leaf area index (LAI) as indicator for biomass status. Initially, the quality aspects of the developed light-weight hyperspectral mapping system will presented with regard to its radiometric and geometric

  1. Large-scale Fresnel lens solar concentrator

    NASA Technical Reports Server (NTRS)

    Allums, S. L.; Hastings, L. J.; Jensen, W. S.

    1977-01-01

    Sun tracking solar collector using lightweight inexpensive acrylic lenses to concentrate sun's energy yields efficiency range of 50 percent at average fluid temperature of 125 C to 26 percent at 300 C.

  2. Plane-polar Fresnel and far-field computations using the Fresnel-Wilcox and Jacobi-Bessel expansions. [for large aperture antennas

    NASA Technical Reports Server (NTRS)

    Rahmat-Samii, Y.; Galindo-Israel, V.

    1981-01-01

    It is pointed out that the computation of the Fresnel fields for large aperture antennas is significant for many applications. The present investigation is concerned with an approach for the effective utilization of the coefficients of the Jacobi-Bessel series for the far-field to obtain an analytically continuous representation of the antenna field which is valid from the Fresnel region into the far field. Attention is given to exact formulations and closed form solutions, Fresnel and Fresnel small angle approximations, aspects of field expansion, the accuracy of the Fresnel and Fresnel small angle approximations, and the Jacobi-Bessel expansion applied to the Fresnel small angle approximation.

  3. Environmental safety analysis tests on the Light Weight Radioisotope Heater Unit (LWRHU)

    SciTech Connect

    Tate, R.E.; Land, C.C.

    1985-05-01

    A series of safety tests has been performed on the Light Weight Radioisotope Heater Unit (LWRHU), a /sup 238/PuO/sub 2/-fueled device designed to provide thermal energy at selected locations in a spacecraft. The tests simulate the thermal and mechanical environments postulated for spacecraft accidents on the launch pad and on reentry abort. The tests demonstrate almost complete containment of the fuel, or fuel simulant (depleted UO/sub 2/), in (1) an overpressure environment of 12.76 MPa (1850 psi), (2) on impact by an 18-g aluminum fuel-tank fragment at velocities greater than 750 m/s (2460 ft/s) but less than 900 m/s (2950 ft/s), (3) during a 10.5-min burn of a 0.9 x 0.9 x 0.9 m (3 x 3 x 3 ft) block of solid rocket motor propellant, (4) after impact at 49 m/s (161 ft/s) in four different orientations on a hard surface, and (5) during immersion in seawater for 1.75 years at both sea level pressure and at a pressure equivalent to 6000 m (19,700 ft) of ocean depth.

  4. Thermography investigations and numerical analysis of turbulent and laminar flow at light weight structures

    NASA Astrophysics Data System (ADS)

    Arndt, Ralf; Gaulke, Alexander

    2008-03-01

    Thermography (IR) allows global visualization of temperature distribution on surfaces with high accuracy. This potential can be used for visualization of fluid mechanics effects at the intersection of laminar and turbulent flows, where temperature jumps appear due to convection and friction i.e. for the optimization in the design of airplane geometries. In civil engineering too it is the aspiration of the modern engineer of light weight structures to meet singular loads like wind peaks rather by intelligent structures and materials than by massive structures. Therefore the "Institute of Conceptual and Structural Design" of the Technical University of Berlin (TUB) is working on the development of adaptive structures, optimized geometry and intelligent microstructures on surfaces of structural elements. The paper shows the potential of modern computational fluid dynamics (CFD) in combination with thermography (IR) to optimize structures by visualization of laminar-tumultuous border layer currents. Therefore CFD simulations and IR wind tunnel experiments will be presented and discussed. For simulations and experiments - artificial and structural elements of the cable-stayed Strelasund Bridge, Germany, are used.

  5. Advanced manufacturing technologies for light-weight post- polished snap-together reflective optical system designs

    NASA Astrophysics Data System (ADS)

    Sweeney, Michael N.

    2002-09-01

    Fast, light weight, off-axis, aspheric, reflective optical designs are increasingly being designed and built for space-based remote sensing, fire control systems, aerial reconnaissance, cryovac instrumentation and laser scanning. Diamond point turning (DPT) is the technology of first resort for many of these applications. In many cases the best diamond machining technologies available cannot meet the desired requirements for system wavefront error and scatter. Aluminum, beryllium, AlBeMet and silicon carbide mirrors, layered with thin films of electroless nickel or silicon can be first diamond machined and then post polished to achieve greatly enhanced performance levels for surface scatter, wavefront error (WFE), and alignment registration. By application of post polishing using precise null testing techniques, the objectives of snap-together, or limited compensation alignment of aggressive reflective optical systems can be achieved that are well beyond the performance envelope achievable by diamond machining alone. This paper discusses the tradeoffs among materials and processes selection for post polished reflective systems and illustrates actual applications including telescopes for earth and Mars orbit, and a commercial, high speed, flat field scan engine.

  6. Implantable electronics: emerging design issues and an ultra light-weight security solution.

    PubMed

    Narasimhan, Seetharam; Wang, Xinmu; Bhunia, Swarup

    2010-01-01

    Implantable systems that monitor biological signals require increasingly complex digital signal processing (DSP) electronics for real-time in-situ analysis and compression of the recorded signals. While it is well-known that such signal processing hardware needs to be implemented under tight area and power constraints, new design requirements emerge with their increasing complexity. Use of nanoscale technology shows tremendous benefits in implementing these advanced circuits due to dramatic improvement in integration density and power dissipation per operation. However, it also brings in new challenges such as reliability and large idle power (due to higher leakage current). Besides, programmability of the device as well as security of the recorded information are rapidly becoming major design considerations of such systems. In this paper, we analyze the emerging issues associated with the design of the DSP unit in an implantable system. Next, we propose a novel ultra light-weight solution to address the information security issue. Unlike the conventional information security approaches like data encryption, which come at large area and power overhead and hence are not amenable for resource-constrained implantable systems, we propose a multilevel key-based scrambling algorithm, which exploits the nature of the biological signal to effectively obfuscate it. Analysis of the proposed algorithm in the context of neural signal processing and its hardware implementation shows that we can achieve high level of security with ∼ 13X lower power and ∼ 5X lower area overhead than conventional cryptographic solutions.

  7. Light weight portable operator control unit using an Android-enabled mobile phone

    NASA Astrophysics Data System (ADS)

    Fung, Nicholas

    2011-05-01

    There have been large gains in the field of robotics, both in hardware sophistication and technical capabilities. However, as more capable robots have been developed and introduced to battlefield environments, the problem of interfacing with human controllers has proven to be challenging. Particularly in the field of military applications, controller requirements can be stringent and can range from size and power consumption, to durability and cost. Traditional operator control units (OCUs) tend to resemble laptop personal computers (PCs), as these devices are mobile and have ample computing power. However, laptop PCs are bulky and have greater power requirements. To approach this problem, a light weight, inexpensive controller was created based on a mobile phone running the Android operating system. It was designed to control an iRobot Packbot through the Army Research Laboratory (ARL) in-house Agile Computing Infrastructure (ACI). The hardware capabilities of the mobile phone, such as Wi- Fi communications, touch screen interface, and the flexibility of the Android operating system, made it a compelling platform. The Android based OCU offers a more portable package and can be easily carried by a soldier along with normal gear requirements. In addition, the one hand operation of the Android OCU allows for the Soldier to keep an unoccupied hand for greater flexibility. To validate the Android OCU as a capable controller, experimental data was collected evaluating use of the controller and a traditional, tablet PC based OCU. Initial analysis suggests that the Android OCU performed positively in qualitative data collected from participants.

  8. Safety analysis for the Galileo Light-Weight Radioisotope Heater Unit

    SciTech Connect

    Johnson, E.W.

    1990-01-01

    The Light-Weight Radioisotope Heater Unit (LWRHU) will be used on the NASA Galileo Mission to provide thermal energy to the various systems on the orbiter and probe that are adversely affected by the low temperature a spacecraft encounters during a long interplanetary mission. Using these plutonia-fueled sources in 1-W increments permits employment of a single design and provides the spacecraft user the option of how many to use and where to position them to satisfy the proper thermal environment for components requiring such consideration. The use of the radioisotope {sup 238}Pu in these devices necessitates the assessment of postulated radiological risks which might be experienced in case of accidents or malfunctions of the space shuttle or the spacecraft during phases of the mission in the vicinity of the earth. Included are data for the design, mission descriptions, postulated accidents with their consequences, test data, and the derived source terms and personnel exposures for the various events. 4 refs., 4 figs., 1 tab.

  9. A High Resolution, Light-Weight, Synthetic Aperture Radar for UAV Application

    SciTech Connect

    Doerry, A.W.; Hensley, W.H.; Stence, J.; Tsunoda, S.I. Pace, F.; Walker, B,C.; Woodring, M.

    1999-05-27

    (U) Sandia National Laboratories in collaboration with General Atomics (GA) has designed and built a high resolution, light-weight, Ku-band Synthetic Aperture Radar (SAR) known as "Lynx". Although Lynx can be operated on a wide variety of manned and unmanned platforms, its design is optimized for use on medium altitude Unmanned Aerial Vehicles (UAVS). In particular, it can be operated on the Predator, I-GNAT, and Prowler II platforms manufactured by GA. (U) The radar production weight is less than 120 lb and operates within a 3 GHz band from 15.2 GHz to 18.2 GHz with a peak output power of 320 W. Operating range is resolution and mode dependent but can exceed 45 km in adverse weather (4 mm/hr rain). Lynx has operator selectable resolution and is capable of 0.1 m resolution in spotlight mode and 0.3 m resolution in stripmap mode, over substantial depression angles (5 to 60 deg) and squint angles (broadside ±45 deg). Real-time Motion Compensation is implemented to allow high-quality image formation even during vehicle turns and other maneuvers.

  10. Light Weight Ceramic Ablators for Mars Follow-on Mission Vehicle Thermal Protection System

    NASA Technical Reports Server (NTRS)

    Tran, Huy K.; Rasky, Daniel J.; Hsu, Ming-Ta; Turan, Ryan

    1994-01-01

    New Light Weight Ceramic Ablators (LCA) were produced by using ceramic and carbon fibrous substrates, impregnated with silicone and phenolic resins. The special infiltration techniques (patent pending) were developed to control the amount of organic resins in the highly porous fiber matrices so that the final densities of LCA's range from 0.22 to 0.24 g/cc. This paper presents the thermal and ablative performance of the Silicone Impregnated Reusable Ceramic Ablators (SIRCA) in simulated entry conditions for Mars-Pathfinder in the Ames 60 MW Interaction Heating Facility (I HF). Arc jet test results yielded no evidence of char erosion and mass loss at high stagnation pressures to 0.25 atm. Minimal silica melt was detected on surface char at a stagnation pressure of 0.31 atm. Four ceramic substrates were used in the production of SIRCA's to obtain the effective of boron oxide present in substrate so the thermal performance of SIRCA's. A sample of SIRCA was also exposed to the same heating condition for five cycles and no significant mass loss or recession was observed. Tensile testing established that the SIRCA tensile strength is about a factor of two higher than that of the virgin substrates. Thermogravimetric Analysis (TGA) of the char in nitrogen and air showed no evidence of free carbon in the char. Scanning Electron Microscopy of the post test sample showed that the char surface consists of a fibrous structure that was sealed with a thin layer of silicon oxide melt.

  11. Ab initio guided design of bcc Mg-Li alloys for ultra light-weight applications

    NASA Astrophysics Data System (ADS)

    Friák, Martin; Counts, William Art; Raabe, Dierk; Neugebauer, Jörg

    2009-03-01

    Ab initio calculations are becoming increasingly useful to engineers interested in designing new alloys because these calculations are able to accurately predict basic material properties only knowing the atomic composition of the material. In this paper, fundamental physical properties (like formation energies and elastic constants) of 11 bcc Mg-Li compounds are calculated using density-functional theory (DFT) and compared with available experimental data. These DFT-determined properties are in turn used to calculate engineering parameters like (i) specific Young's modulus (Y/ρ) or (ii) bulk over shear modulus ratio (B/G) differentiating between brittle and ductile behavior. The engineering parameters are then used to identify alloys that have optimal mechanical properties needed for a light weight structural material. It was found that the stiffest bcc magnesium-lithium alloys contain about 70 at.% Mg while the most ductile alloys have 0-20 at.% Mg. The specific modulus for alloys with 70 at.% Mg is equal to that of Al-Mg alloys. An Ashby map containing Y/ρ vs. B/G shows that it is not possible to increase both Y/ρ and B/G by changing only the composition or local order of a binary alloy (W. A. Counts, M. Fri'ak, D. Raabe and J. Neugebauer, Acta Mater 57 (2009) 69-76).

  12. The Optical Harness: a light-weight EMI-immune replacement for legacy electrical wiring harnesses

    NASA Astrophysics Data System (ADS)

    Stark, Jason B.; Jackson, B. Scott; Trethewey, William

    2006-05-01

    Electrical wiring harnesses have been used to interconnect control and communication equipment in mobile platforms for over a century. Although they have served this function successfully, they have three problems that are inherent in their design: they are mechanically heavy and stiff, and they are prone to electrical faults, including arcing and Electro-Magnetic Interference (EMI), and they are difficult to maintain when faults occur. These properties are all aspects of the metallic conductors used to build the harnesses. The Optical Harness TM is a photonic replacement for the legacy electrical wiring harness. The Optical Harness TM uses light-weight optical fiber to replace signal wires in an electrical harness. The original electrical connections to the equipment remain, making the Optical Harness TM a direct replacement for the legacy wiring harness. In the backshell of each connector, the electrical signals are converted to optical, and transported on optical fiber, by a deterministic, redundant and fault-tolerant optical network. The Optical Harness TM: * Provides weight savings of 40-50% and unsurpassed flexibility, relative to legacy signal wiring harnesses; * Carries its signals on optical fiber that is free from arcing, EMI, RFI and susceptibility to HPM weapons; * Is self-monitoring during operation, providing non-intrusive predictive and diagnostic capabilities.

  13. Testing of Large Diameter Fresnel Optics for Space Based Observations of Extensive Air Showers

    NASA Technical Reports Server (NTRS)

    Adams, James H.; Christl, Mark J.; Young, Roy M.

    2011-01-01

    The JEM-EUSO mission will detect extensive air showers produced by extreme energy cosmic rays. It operates from the ISS looking down on Earth's night time atmosphere to detect the nitrogen fluorescence and Cherenkov produce by the charged particles in the EAS. The JEM-EUSO science objectives require a large field of view, sensitivity to energies below 50 EeV, and must fit within available ISS resources. The JEM-EUSO optic module uses three large diameter, thin plastic lenses with Fresnel surfaces to meet the instrument requirements. A bread-board model of the optic has been manufactured and has undergone preliminary tests. We report the results of optical performance tests and evaluate the present capability to manufacture these optical elements.

  14. Development of a dome Fresnel lens/gallium arsenide photovoltaic concentrator for space applications

    NASA Technical Reports Server (NTRS)

    O'Neill, Mark J.; Piszczor, Michael F.

    1987-01-01

    A novel photovoltaic concentrator system is currently being developed. Phase I of the program, completed in late 1986, produced a conceptual design for the concentrator system, including an array weight and performance estimates based on optical, electrical, and thermal analyses. Phase II of the program, just underway, concerns the fabrication and testing of prototype concentrator panels of the design. The concentrator system uses dome Fresnel lenses for optical concentration; gallium arsenide concentrator cells for power generation; prismatic cell covers to eliminate gridline obscuration losses; a backplane radiator for heat rejection; and a honeycomb structure for the deployable panel assembly. The conceptual design of the system, its anticipated performance, and its estimated weight are reported.

  15. An analytical and experimental evaluation of a Fresnel lens solar concentrator

    NASA Technical Reports Server (NTRS)

    Hastings, L. J.; Allums, S. A.; Cosby, R. M.

    1976-01-01

    An analytical and experimental evaluation of line focusing Fresnel lenses with application potential in the 200 to 370 C range was studied. Analytical techniques were formulated to assess the solar transmission and imaging properties of a grooves down lens. Experimentation was based on a 56 cm wide, f/1.0 lens. A Sun tracking heliostat provided a nonmoving solar source. Measured data indicated more spreading at the profile base than analytically predicted, resulting in a peak concentration 18 percent lower than the computed peak of 57. The measured and computed transmittances were 85 and 87 percent, respectively. Preliminary testing with a subsequent lens indicated that modified manufacturing techniques corrected the profile spreading problem and should enable improved analytical experimental correlation.

  16. Learning through Different Lenses

    ERIC Educational Resources Information Center

    Jeweler, Sue; Barnes-Robinson, Linda

    2015-01-01

    When parents and teachers help gifted kids use the metaphor "learning through different lenses," amazing things happen: Horizons open up. Ideas are focused. Thoughts are magnified and clarified. They see the big picture. Metaphoric thinking offers new and exciting ways to see the world. Viewing the world through different lenses provides…

  17. One Episode, Two Lenses

    ERIC Educational Resources Information Center

    Drijvers, Paul; Godino, Juan D.; Font, Vicenc; Trouche, Luc

    2013-01-01

    A deep understanding of students' learning processes is one of the core challenges of research in mathematics education. To achieve this, different theoretical lenses are available. The question is how these different lenses compare and contrast, and how they can be coordinated and combined to provide a more comprehensive view on the topic of…

  18. Focal length measurement based on Fresnel diffraction from a phase plate.

    PubMed

    Dashtdar, Masoomeh; Mohammad-Ali Hosseini-Saber, S

    2016-09-10

    A method based on the Fresnel diffraction of light from the phase step is introduced for measuring effective focal length (EFL) and back focal length (BFL) of optical imaging systems. It is shown that, as a transparent plane-parallel plate is illuminated at a boundary region by a monochromatic beam of light, Fresnel diffraction occurs because of the abrupt change in phase imposed by the finite change in refractive index at the plate boundary. Variation of the incident angle in a convergent (or divergent) beam of light causes the periodic intensity along the central fringe of the diffraction pattern. The measurement of the extrema position of the intensity distribution accurately provides the EFL and BFL. The technique is easy to apply and can measure a wide range of both positive and negative focal lengths. The measuring setup can be very compact with low mechanical and optical noises. As examples of this technique, the EFLs of five different lenses are experimentally obtained. The results are quite consistent with the values indicated by the lens manufacturer.

  19. Cylindrical diffractive lenses recorded on PVA/AA photopolymers

    NASA Astrophysics Data System (ADS)

    Fernández, R.; Gallego, S.; Márquez, A.; Navarro-Fuster, V.; Francés, J.; Neipp, C.; Beléndez, A.; Pascual, I.

    2016-04-01

    Photopolymers are optical recording materials appealing for many different applications such as holography, data storage, interconnectors, solar concentrations, or wave-guides fabrication. Recently the capacity of photopolymers to record diffractive optical elements (DOE's) has been investigated. Different authors have reported proposes to record DOE like fork gratings, photonics structures, lenses, sinusoidal, blazed or fork gratings. In these experiments there are different experimental set-ups and different photopolymers. In this work due to the improvement in the spatial light modulation technology together with the photopolymer science we propose a recording experimental system of DOE using a Liquid Cristal based on Silicon (LCoS) display as a master to store complex DOE like cylindrical lenses. This technology permits us an accurate control of the phase and the amplitude of the recording beam, with a very small pixel size. The main advantage of this display is that permit us to modify the DOE automatically, we use the software of the LCoS to send the voltage to each pixel In this work we use a photopolymer composed by acrylamide (AA) as polymerizable monomer and polyvinyl alcohol (PVA). We use a coverplated and index matched photopolymer to avoid the influence of the thickness variation on the transmitted light. In order to reproduce the material behaviour during polymerization, we have designed our model to simulate cylindrical lenses and used Fresnel propagation to simulate the light propagation through the DOE and analyze the focal plane and the properties of the recorded lenses.

  20. Aspherics in spectacle lenses

    NASA Astrophysics Data System (ADS)

    Dürsteler, Juan Carlos

    2016-12-01

    A review of the use of aspherics in the last decades, understood in a broad sense as encompassing single-vision lenses with conicoid surfaces and free-form and progressive addition lenses (PALs) as well, is provided. The appearance of conicoid surfaces to correct aphakia and later to provide thinner and more aesthetically appealing plus lenses and the introduction of PALs and free-form surfaces have shaped the advances in spectacle lenses in the last three decades. This document basically considers the main target optical aberrations, the idiosyncrasy of single lenses for correction of refractive errors and the restrictions and particularities of PAL design and their links to science vision and perception.

  1. Ultra-light weight undamped tuned dynamic absorber for cryogenically cooled infrared electro-optic payload

    NASA Astrophysics Data System (ADS)

    Veprik, Alexander; Babitsky, Vladimir

    2017-04-01

    Attenuation of tonal cryocooler induced vibration in infrared electro-optical payloads may be achieved by using of Tuned Dynamic Absorber (TDA) which is, generally speaking, a passive, weakly damped mass-spring system the resonant frequency of which is precisely matched with the driving frequency. Added TDA results in a favorable modification of the frequency response functions of combined structure. In particular, a favorable antiresonant notch appears at the frequency of tonal excitation along with the adjacent secondary resonance, the width and depth of which along with its closeness to the secondary resonance are strongly dependent on the mass and damping ratios. Using heavier TDA favorably results in wider and deeper antiresonant notch along with increased gap between antiresonant and resonant frequencies. Lowering damping in TDA favorably results in deepening the antiresonant notch. The weight of TDA is usually subjected to tight design constrains. Use of lightweight TDA not only diminishes the attainable performance but also complicates the procedure of frequency matching. Along these lines, even minor frequency deviations may negate the TDA performance and even result in TDA failure in case of resonant build up. The authors are presenting theoretical and practical aspects of designing and constructing ultra-light weight TDA in application to vibration attenuation of electro-optical infrared payload relying on Split Stirling linear cryocooler, the driving frequency of which is fixed and may be accurately tuned and maintained using a digital controller over the entire range of working conditions and lifetime; the lack of mass ratio is compensated by minimizing the damping ratio. In one particular case, in excess of 100-fold vibration attenuation has been achieved by adding as little as 5% to the payload weight.

  2. Development of Light Weight High Strength Carbon Dioxide Monitor for Sub Orbital Space Craft

    NASA Astrophysics Data System (ADS)

    Karavolos, A. P.

    2011-12-01

    Introduction No commercially material is currently available that can satisfy the performance requirements for Suborbital Sampling of Carbon Dioxide in air .Satellite interrogation is not feasible because of the low altitude, and the altitude is too high for satisfactory performance from balloons. A hybrid material in a light weight canister may be the solution to satisfying the above requirements. An example fiber with carbon dioxide capture agent is wound in an equilateral triangle pattern 3 mm in diameter, and heat bonded to a carbon fiber panel. A layer of polypropylene-methyl cellulose 1 mm thick underlies the carbon fiber. The interior contains a metallized organic polymer heat bonded to this surface. Methodology All component materials were purchased through 3M and Sigma Aldrich Chemical Company. The carbon prepreg panel was first placed in a stainless steel mold for non reactivity with container. Polypropylene powder was homogenized with various percentages of methyl cellulose powder and tantalum nano particles. This mixture was then placed in a mold to make panel parts; epoxy bonded to a carbon fiber resin prepreg, and allowed to outgas for 24 hours before materials and chemical testing. Preliminary Results Preliminary finding of the newly tested material are shown in the table below are that the tensile strength is about 74.5 kPa, has maximum CO2 capture efficiency, and regeneration of O2 by weight of total CO2 captured. Conclusions Based on the initial experimentation accomplished, it appears that the proposed hybrid construction of carbon pre preg backing material, coupled with an inner lining of polypropylene-methyl cellulose, satisfies the strength requirements of the habitat building material. In addition, carbon dioxide adsorption and oxygen replenishment requirements also have been met.

  3. Linear Fresnel Spectrometer Chip with Gradient Line Grating

    NASA Technical Reports Server (NTRS)

    Choi, Sang Hyouk (Inventor); Park, Yeonjoon (Inventor)

    2015-01-01

    A spectrometer that includes a grating that disperses light via Fresnel diffraction according to wavelength onto a sensing area that coincides with an optical axis plane of the grating. The sensing area detects the dispersed light and measures the light intensity associated with each wavelength of the light. Because the spectrometer utilizes Fresnel diffraction, it can be miniaturized and packaged as an integrated circuit.

  4. A New Way to Evaluate the Probability and Fresnel Integrals

    ERIC Educational Resources Information Center

    Khalili, Parviz

    2007-01-01

    In this article, we show how "Laplace Transform" may be used to evaluate variety of nontrivial improper integrals, including "Probability" and "Fresnel" integrals. The algorithm we have developed here to evaluate "Probability, Fresnel" and other similar integrals seems to be new. This method transforms the evaluation of certain improper integrals…

  5. Color-corrected Fresnel lens for solar concentration

    SciTech Connect

    Kritchman, E.M.

    1980-01-01

    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.

  6. Parametrization of Fresnel returns in middle-atmosphere radar experiments

    NASA Technical Reports Server (NTRS)

    Rastogi, P. K.

    1983-01-01

    Weak reflections from sharp discontinuities in radio refractivity are usually invoked to explain the results of radio propagation experiments. The characteristics of refractivity structures required to produce Fresnel returns are examined and experimental evidence for Fresnel returns in middle-atmosphere radar experiments is reviewed. The consequences of these returns on estimating the turbulence and wind parameters are outlined.

  7. Switchable Fresnel lens based on micropatterned alignment.

    PubMed

    Wang, Xiao-Qian; Srivastava, Abhishek K; Chigrinov, Vladimir G; Kwok, Hoi-Sing

    2013-06-01

    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. The FZL profile for both optical regimes, i.e., in TN and PA alignment domains, generates the same focal length (f). Thus, the proposed LCFZL manifests double light intensity at the focal point and therefore offers double the efficiency of existing FZLs. Moreover, because of lower driving voltage and fast response, these elements could find application in many modern devices.

  8. Linear Fresnel lens photovoltaic concentrator program

    SciTech Connect

    Kull, J.; Maraschin, R.; Rafinejad, D.; Spencer, R.; Sutton, G.

    1983-08-01

    This report describes Acurex Corporation's design of a linear Fresnel lens Photovoltaic Concentrator Panel. The panel consists of four concentrator modules in an integrated structure. Each module is 10 ft long and has a 39.85 in aperture. The solar cell's active width is 0.90 in. and the cell-lens edge spacing is 23.39 in. There are 58 cells per module. A prototype panel was built and tested. Test results showed a peak electrical efficiency of 10.5% at the operating conditions of 800 W/m/sup 2/ insolation and 90/sup 0/F coolant temperature. The prototype exhibits the manufacturing and assembly concepts developed.

  9. Solar Tracking Error Analysis of Fresnel Reflector

    PubMed Central

    Zheng, Jiantao; Yan, Junjie; Pei, Jie; Liu, Guanjie

    2014-01-01

    Depending on the rotational structure of Fresnel reflector, the rotation angle of the mirror was deduced under the eccentric condition. By analyzing the influence of the sun tracking rotation angle error caused by main factors, the change rule and extent of the influence were revealed. It is concluded that the tracking errors caused by the difference between the rotation axis and true north meridian, at noon, were maximum under certain conditions and reduced at morning and afternoon gradually. The tracking error caused by other deviations such as rotating eccentric, latitude, and solar altitude was positive at morning, negative at afternoon, and zero at a certain moment of noon. PMID:24895664

  10. Nanometer displacement measurement using Fresnel diffraction.

    PubMed

    Khorshad, Ali Akbar; Hassani, Khosrow; Tavassoly, Mohammad Taghi

    2012-07-20

    We introduce a relatively simple and efficient optical technique to measure nanoscale displacement based on visibility variations of the Fresnel diffraction fringes from a two-dimensional phase step. In this paper we use our technique to measure electromechanical expansions by a thin piezoelectric ceramic and also thermal changes in the diameter of a tungsten wire. Early results provide convincing evidence that sensitivity up to a few nanometers can be achieved, and our technique has the potential to be used as a nanodisplacement probe.

  11. Mathematical Simulation for Integrated Linear Fresnel Spectrometer Chip

    NASA Technical Reports Server (NTRS)

    Park, Yeonjoon; Yoon, Hargoon; Lee, Uhn; King, Glen C.; Choi, Sang H.

    2012-01-01

    A miniaturized solid-state optical spectrometer chip was designed with a linear gradient-gap Fresnel grating which was mounted perpendicularly to a sensor array surface and simulated for its performance and functionality. Unlike common spectrometers which are based on Fraunhoffer diffraction with a regular periodic line grating, the new linear gradient grating Fresnel spectrometer chip can be miniaturized to a much smaller form-factor into the Fresnel regime exceeding the limit of conventional spectrometers. This mathematical calculation shows that building a tiny motionless multi-pixel microspectrometer chip which is smaller than 1 cubic millimter of optical path volume is possible. The new Fresnel spectrometer chip is proportional to the energy scale (hc/lambda), while the conventional spectrometers are proportional to the wavelength scale (lambda). We report the theoretical optical working principle and new data collection algorithm of the new Fresnel spectrometer to build a compact integrated optical chip.

  12. Stress-Detection Lenses

    NASA Technical Reports Server (NTRS)

    1996-01-01

    An Ames Research Center scientist invented an infrared lens used in sunglasses to filter out ultraviolet rays. This product finds its origins in research for military enemy detection. Through a Space Act Agreement, Optical Sales Corporation introduced the Hawkeye Lenses not only as sunglasses but as plant stress detection lenses. The lenses enhance the stressed part of the leaf, which has less chlorophyll than healthy leaves, through dyes that filter out certain wavelengths of light. Plant stress is visible earlier, at a stage when something can be done to save the plants.

  13. Numerical analysis for finite Fresnel transform

    NASA Astrophysics Data System (ADS)

    Aoyagi, Tomohiro; Ohtsubo, Kouichi; Aoyagi, Nobuo

    2016-10-01

    The Fresnel transform is a bounded, linear, additive, and unitary operator in Hilbert space and is applied to many applications. In this study, a sampling theorem for a Fresnel transform pair in polar coordinate systems is derived. According to the sampling theorem, any function in the complex plane can be expressed by taking the products of the values of a function and sampling function systems. Sampling function systems are constituted by Bessel functions and their zeros. By computer simulations, we consider the application of the sampling theorem to the problem of approximating a function to demonstrate its validity. Our approximating function is a circularly symmetric function which is defined in the complex plane. Counting the number of sampling points requires the calculation of the zeros of Bessel functions, which are calculated by an approximation formula and numerical tables. Therefore, our sampling points are nonuniform. The number of sampling points, the normalized mean square error between the original function and its approximation function and phases are calculated and the relationship between them is revealed.

  14. Modified Fresnel Laws for Optical Microcavities

    NASA Astrophysics Data System (ADS)

    Gagnon, D.; Painchaud-April, G.; Poirier, J.; Dubé, L. J.

    2010-03-01

    The scattering of waves at a planar interface between two dielectric media is governed by Fresnel laws. The associated Fresnel coefficients exhibit a discontinuity at the critical angle of incidence, χc, resulting in total internal reflection for χ>=χc. However modern microresonators are often so small that corrections to the planar approximation become necessary. For instance, a plane wave incident on a curved interface can escape the optically denser medium even for angles larger than χc. In the spirit of Snyder and Love [1], we have derived smooth reflection and transmission coefficients. Interface curvature is accounted for by only modifying the wavefunction describing propagation in the less optically dense medium. The theory is applied to dielectric cavities and our results compared to those of an independent calculation obtained from a sequential-reflection model [2]. The advantages and limitations of our alternative approach will be discussed at the conference.[4pt] [1] A. W. Snyder and J. D. Love, IEEE Trans. Microwave Theory Tech., 23, 134--141, 1975.[0pt] [2] M. Hentschel and H. Schomerus, Phys. Rev. E., 65, 045603(R), 2002.

  15. Kinematic control model for light weighting mechanism of excavator attached to rotary working device

    NASA Astrophysics Data System (ADS)

    Lee, Choongho; Lee, Sangsik; Cho, Youngtae; Im, Kwanghee

    2007-07-01

    An excavator attached to a rotary working device is used principally in industrial work. In particular, they are used in the building industry and public works. This research concerns the rotary automatic control of an excavator attached to a rotary working device. The drilling excavator is used in the crushed stone industry and the dragline excavation system is employed in the construction industry. Cases of the excavator's use in agriculture have been the subject of a relatively few studies. However, several modified excavator designs have been released in recent years. Applied excavator products are primarily utilized under relatively severe environmental conditions. In this study, we focus on the uses of an excavator in agricultural work. The readjustment of arable land and the reduction of weeds in agricultural applications both require skilled hand-operation of the machines. As such workers have been shown to develop problems with regard to working posture and proper positioning while laboring, a more appropriate excavator design may prove useful in such applications. Therefore, this pilot study is focused primarily on the rotary automatic control of an excavator attached to a rotary working device, and will adapt smart materials to the excavator applications for developing redesigned excavator having a light weight. The excavator is attached to a rotary working device on a normal excavator's platform, and the position and orientation of the mechanism between the joints and the rotary working device was determined. Simulations were also conducted of the excavator attached to the rotary working device. With an eye toward the use of this mechanism in agricultural work, we also conducted a set of kinematic analyses. The rotary working device was assumed to have 3 DOF, and was comprised of 5 links. Computer simulations were also conducted using the developed excavator model. In order to adequately evaluate the possible performance of such a system, kinetic

  16. Universal liquid level sensor employing Fresnel coefficient based discrete fiber optic measurement technique

    NASA Astrophysics Data System (ADS)

    Murshid, Syed H.

    2014-09-01

    A compact and light weight liquid-level-measuring system based on fiber-optics sensor technology is presented as alternative to systems based on float gauges and other conventional level sensors for liquids that pose fire, corrosion and explosion hazards. These Fresnel reflection based fiber-optic sensors are inherently safer because they do not include electrical connections inside fuel/chemical tanks, and they exploit changes in internal reflection of guided electromagnetic modes as a result of contact between the outer surface of optical fiber and a liquid. Discrete changes in light transmission/reflection are used to indicate that liquid has come into contact with a suitably designed fiber optic probe at the output end of the fiber. This endeavor presents a quasi-continuous fiber optic level detection system that measures liquid level to within known increments of depth, by placing the probes of a number of such sensors at known depths in a tank where each probe effectively serves as a level switch. Due to the fiber optic nature of the design, the system can operate from cryogenic applications to boiling fluids. Experimental results for liquid nitrogen and water are presented.

  17. A Secure and Efficient Handover Authentication Based on Light-Weight Diffie-Hellman on Mobile Node in FMIPv6

    NASA Astrophysics Data System (ADS)

    Choi, Jaeduck; Jung, Souhwan

    This letter proposes a secure and efficient handover authentication scheme that requires a light-weight Diffie-Hellman operation at mobile nodes. Our scheme provides more enhanced securities like the PFS, PBS, and so on than the existing security-context-transfer schemes. Also, the mobile node delegates the exponent operation for the DH to the access router to reduce computational cost on it.

  18. Soft contact lenses

    PubMed Central

    Sutherland, R. L.; VanLeeuwen, Wm. N.

    1972-01-01

    A series of 55 patients were fitted with a new type of hydrophilic soft contact lens. These were found more comfortable than hard contact lenses and they had a protective and pain-relieving action in cases of chronic corneal disease. Vision was not as good as with hard contact lenses and a greater potential danger of infection was found. They are preferred by many patients despite the noticeable thick edge and the difficulty of obtaining an identical replacement. PMID:5042887

  19. Micron-Accurate Laser Fresnel-Diffraction Ranging System

    NASA Technical Reports Server (NTRS)

    Lehner, David; Campbell, Jonathan; Smith, Kelly; Sanders, Alvin; Allison, Stephen; Smaley, Larry

    2008-01-01

    Two versions of an optoelectronic system undergoing development are depicted. The system is expected to be capable of measuring a distance between 2 and 10 m with an error of no more than 1 micrometer. The system would be designed to exploit Fresnel diffraction of a laser beam. In particular, it would be designed to take advantage of the fact that a Fresnel diffraction pattern is ultrasensitive to distance. The two versions would differ in the following respects: In version 1, the focus of the telescope would be in the Fresnel region, and the telescope would have a small depth of focus. As a consequence, the Fresnel pattern would be imaged directly onto the photodetector array; in version 2, a multielement lens module would displace the Fresnel region from the vicinity of the pinhole to the vicinity of the optical receiver. As the distance to be measured varied, the location of the receiver relative to the displaced Fresnel-diffraction region would vary, thereby causing the Fresnel diffraction pattern on the focal plane to vary. The multielement lens module would also correct for aberrations. The processing of the digitized Fresnel diffraction pattern in the computer might be accelerated by using only parts of the pattern or even only one small part - the central pixel. As the distance from the pinhole increased, the central pixel would rapidly cycle between maximum and minimum light intensity. This in itself would not be sufficient to uniquely determine the distance. However, by varying the size of the pinhole or the wavelength of the laser, one could obtain a second cycle of variation of intensity that, in conjunction with the first cycle, could enable a unique determination of distance. Alternatively, for a single wavelength and a single pinhole size, it should suffice to consider the data from only two different key pixels in the Fresnel pattern.

  20. An EUV Fresnel zoneplate mask-imaging microscope for lithography generations reaching 8 nm

    NASA Astrophysics Data System (ADS)

    Goldberg, Kenneth A.; Mochi, Iacopo; Rekawa, Senajith B.; Smith, Nathan S.; Macdougall, James B.; Naulleau, Patrick P.

    2011-04-01

    We present the potential optical performance capabilities of a next-generation extreme ultraviolet (EUV) mask-imaging microscope, based on the proven optical principle of the SEMATECH Berkeley Actinic Inspection Tool (AIT), but surpassing it in every performance metric. The new synchrotron-based tool, referred to here as the SEMATECH Berkeley Actinic Imaging Tool at 0.5 NA (AIT5) will enable research on multiple generations of EUV lithography design rules. The proposed microscope features an array of user-selectable Fresnel zoneplate lenses with diffractionlimited quality and different optical properties, such as numerical aperture (NA) and magnification. An efficient all-EUV optical system with variable high magnification and direct EUV detection provides images with the highest possible signal-to-noise ratio. A lossless, customizable-coherence illuminator based on angle-scanning mirrors and an ellipsoidal condenser creates arbitrary pupil fill patterns, with partial coherence σ values up to 1.0 at 0.5 4×NA and higher. In combination with rotated zoneplate objective lenses, the illuminator will be capable of a range of discrete azimuthal angles as well, modeling the behavior of EUV steppers across a ring-field of view.

  1. Performance characteristics of a 1.8 by 3.7 meter Fresnel lens solar concentrator

    NASA Technical Reports Server (NTRS)

    Hastings, L. J.; Allums, S. L.

    1979-01-01

    Line-focusing acrylic Fresnel lenses with application potential in the 200 to 370 C range were analytically and experimentally investigated. The measured solar concentration characteristics of a 1.8 by 3.7 m lens and its utilization in a solar collection mode are presented. A measured peak concentration ratio of 62 with 90 percent of the transmitted energy focused into a 5.0cm width was achieved. A peak concentration of 59 and a 90 percent target width of 4.3 cm were analytically computed. The experimental and analytical lens transmittance was 78 percent and 86 percent, respectively. The lens was also interfaced with a nonevacuated receiver assembly and operated in the collection mode. With a natural oxide absorber tube coating (alpha/epsilon = 0.79/0.10), the measured collection efficiency ranged from 43 percent to 200 C to 34 percent at 260 C. Efficiency improvements to the 40 to 50 percent range can be achieved with second generation lenses and higher performance absorptive coatings.

  2. Solar concentrator modules with silicone-onglass Fresnel lens panels and multijunction cells.

    PubMed

    Rumyantsev, Valery D

    2010-04-26

    High-efficiency multijunction (MJ) solar cells, being very expensive to manufacture, should only be used in combination with solar concentrators in terrestrial applications. An essential cost reduction of electric power produced by photovoltaic (PV) installations with MJ cells, may be expected by the creation of highly-effective, but inexpensive, elements for optical concentration and sun tracking. This article is an overview of the corresponding approach under development at the Ioffe Physical Technical Institute. The approach to R&D of the solar PV modules is based on the concepts of sunlight concentration by small-aperture area Fresnel lenses and "all-glass" module design. The small-aperture area lenses are arranged as a panel with silicone-on-glass structure where the glass plate serves as the front surface of a module. In turn, high-efficiency InGaP/(In)GaAs/Ge cells are arranged on a rear module panel mounted on a glass plate which functions as a heat sink and integrated protective cover for the cells. The developed PV modules and sun trackers are characterized by simple design, and are regarded as the prototypes for further commercialization.

  3. Solar concentrator modules with silicone-on-glass Fresnel lens panels and multijunction cells.

    PubMed

    Rumyantsev, Valery D

    2010-04-26

    High-efficiency multijunction (MJ) solar cells, being very expensive to manufacture, should only be used in combination with solar concentrators in terrestrial applications. An essential cost reduction of electric power produced by photovoltaic (PV) installations with MJ cells, may be expected by the creation of highly-effective, but inexpensive, elements for optical concentration and sun tracking. This article is an overview of the corresponding approach under development at the Ioffe Physical Technical Institute. The approach to R&D of the solar PV modules is based on the concepts of sunlight concentration by small-aperture area Fresnel lenses and "all-glass" module design. The small-aperture area lenses are arranged as a panel with silicone-on-glass structure where the glass plate serves as the front surface of a module. In turn, high-efficiency InGaP/(In)GaAs/Ge cells are arranged on a rear module panel mounted on a glass plate which functions as a heat sink and integrated protective cover for the cells. The developed PV modules and sun trackers are characterized by simple design, and are regarded as the prototypes for further commercialization.

  4. Description of optical aberrations in dynamic Fresnel dish concentrators

    SciTech Connect

    Borton, D.N.; Borton, C.J.

    1995-10-01

    Tracking solar dish concentrators have the highest efficiencies of solar devices. Traditional paraboloidal dish systems have the best optics, but are limited in size by mechanical constraints. Fresnel dishes can be made larger and are cheaper than paraboloidal dishes, but have optical imperfections. This paper describes a mathematical model of a dynamic Fresnel dish concentrator, and examines its optics. Optical aberrations of any design can be described for any day of the year. In general, the aberrations are small and the benefits of a Fresnel design outweigh the loss in optical performance. The model can be used to design concentrators for any application including distributed dish electric power generating systems.

  5. Multi-tower line focus Fresnel array project

    SciTech Connect

    Mills, D.R.; Morrison, G.; Pye, J.; Le Lievre, P.

    2006-02-15

    As an alternative to conventional tracking solar thermal trough systems, one may use line focus Fresnel reflector systems. In a conventional Fresnel reflector design, each field of reflectors is directed to a single tower. However efficient systems of very high ground utilisation can be setup if a field of reflectors uses multiple receivers on different towers. This paper describes a line focus system, called the compact linear fresnel reflector system and a project to produce an initial 95 MWth solar array. The array will be used as a retrofit preheater for a coal fired generating plant.

  6. Dynamical theory of stratified Fresnel linear zone plates

    SciTech Connect

    Sammar, A.; Andre, J.M.

    1993-11-01

    A dynamical theory is given for calculating the performances of stratified Fresnel linear zone plates (SFLZP`s). The Born expansion extended to the Fresnel diffraction is used to prove a fundamental theorem giving the diffraction efficiency and the diffraction pattern of transmission or reflection SFLZP`s. The method is valuable as long as the wavelength is smaller than the characteristic parameter of the zone plate. It allows us to evaluate the performances of reflection multilayer SFLZPs, i.e., the so-called Bragg-Fresnel optics recently developed for x-ray optics. 17 refs., 8 figs.

  7. Fresnel diffraction mirror for an atomic wave.

    PubMed

    Oberst, Hilmar; Kouznetsov, Dimitrii; Shimizu, Kazuko; Fujita, Jun-Ichi; Shimizu, Fujio

    2005-01-14

    We have experimentally demonstrated a material-independent mirror for atomic waves that uses the Fresnel diffraction at an array of parallel ridges. He* (2 (3)S(1)) and Ne* (1s(3)) atomic waves were reflected coherently on a silicon plate with a microfabricated grating structure, consisting of narrow wall-like ridges. We measured the reflectivity at grazing incidence as a function of the incident velocity and angle. Our data show that the reflectivity on this type of mirror depends only on the distance between the ridges, the wavelength, and the incident angle, but is insensitive to the material of the grating structure. The reflectivity is observed to increase by 2 orders of magnitude, compared to that of a flat polished silicon surface, where the reflection is caused by the attractive surface potential. For He* atoms, the measured reflectivity exceeds 10% for normal incident velocities below about 25 cm/s.

  8. Weak Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Pires, Sandrine; Starck, Jean-Luc; Leonard, Adrienne; Réfrégier, Alexandre

    2012-03-01

    This chapter reviews the data mining methods recently developed to solve standard data problems in weak gravitational lensing. We detail the different steps of the weak lensing data analysis along with the different techniques dedicated to these applications. An overview of the different techniques currently used will be given along with future prospects. Until about 30 years ago, astronomers thought that the Universe was composed almost entirely of ordinary matter: protons, neutrons, electrons, and atoms. The field of weak lensing has been motivated by the observations made in the last decades showing that visible matter represents only about 4-5% of the Universe (see Figure 14.1). Currently, the majority of the Universe is thought to be dark, that is, does not emit electromagnetic radiation. The Universe is thought to be mostly composed of an invisible, pressure less matter - potentially relic from higher energy theories - called "dark matter" (20-21%) and by an even more mysterious term, described in Einstein equations as a vacuum energy density, called "dark energy" (70%). This "dark" Universe is not well described or even understood; its presence is inferred indirectly from its gravitational effects, both on the motions of astronomical objects and on light propagation. So this point could be the next breakthrough in cosmology. Today's cosmology is based on a cosmological model that contains various parameters that need to be determined precisely, such as the matter density parameter Omega_m or the dark energy density parameter Omega_lambda. Weak gravitational lensing is believed to be the most promising tool to understand the nature of dark matter and to constrain the cosmological parameters used to describe the Universe because it provides a method to directly map the distribution of dark matter (see [1,6,60,63,70]). From this dark matter distribution, the nature of dark matter can be better understood and better constraints can be placed on dark energy

  9. Thermal lensing in optical fibers.

    PubMed

    Dong, Liang

    2016-08-22

    Average powers from fiber lasers have reached the point that a quantitative understanding of thermal lensing and its impact on transverse mode instability is becoming critical. Although thermal lensing is well known qualitatively, there is a general lack of a simple method for quantitative analysis. In this work, we first conduct a study of thermal lensing in optical fibers based on a perturbation technique. The perturbation technique becomes increasingly inaccurate as thermal lensing gets stronger. It, however, provides a basis for determining a normalization factor to use in a more accurate numerical study. A simple thermal lensing threshold condition is developed. The impact of thermal lensing on transverse mode instability is also studied.

  10. 3D integral imaging using diffractive Fresnel lens arrays.

    PubMed

    Hain, Mathias; von Spiegel, Wolff; Schmiedchen, Marc; Tschudi, Theo; Javidi, Bahram

    2005-01-10

    We present experimental results with binary amplitude Fresnel lens arrays and binary phase Fresnel lens arrays used to implement integral imaging systems. Their optical performance is compared with high quality refractive microlens arrays and pinhole arrays in terms of image quality, color distortion and contrast. Additionally, we show the first experimental results of lens arrays with different focal lengths in integral imaging, and discuss their ability to simultaneously increase both the depth of focus and the field of view.

  11. Signal-enhancement reflective pulse oximeter with Fresnel lens

    NASA Astrophysics Data System (ADS)

    Chung, Shuang-Chao; Sun, Ching-Cherng

    2016-09-01

    In this paper, a new reflective pulse oximeter is proposed and demonstrated with implanting a Fresnel lens, which enhances the reflected signal. An optical simulation model incorporated with human skin characteristics is presented to evaluate the capability of the Fresnel lens. In addition, the distance between the light emitting diode and the photodiode is optimized. Compared with the other reflective oximeters, the reflected signal light detected by the photodiode is enhanced to more than 140%.

  12. Space power system utilizing Fresnel lenses for solar power and also thermal energy storage

    NASA Technical Reports Server (NTRS)

    Turner, R. H.

    1983-01-01

    A solar power plant suitable for earth orbits passing through Van Allen radiation belts is described. The solar-to-electricity conversion efficiency is estimated to be around 9 percent, and the expected power-to-weight ratio is competitive with photovoltaic arrays. The system is designed to be self-contained, to be indifferent to radiation belt exposures, store energy for periods when the orbiting system is in earth shadow (so that power generation is contant), have no moving parts and no working fluids, and be robust against micrometeorite attack. No electrical batteries are required.

  13. An advanced space photovoltaic concentrator array using Fresnel lenses, gallium arsenide cells, and prismatic cell covers

    NASA Technical Reports Server (NTRS)

    O'Neill, Mark J.; Piszczor, Michael F.

    1988-01-01

    The current status of a space concentrator array which uses refractive optics, gallium arsenide cells, and prismatic cell covers to achieve excellent performance at a very low array mass is documented. The prismatically covered cells have established records for space cell performance (24.2 percent efficient at 100 AM0 suns and 25 C) and terrestrial single-junction cell performance (29.3 percent efficient at 200 AM1.5 suns and 25 C).

  14. 30 kW concentrator photovoltaic system using dome-shaped Fresnel lenses.

    PubMed

    Araki, Kenji; Yano, Taizo; Kuroda, Yoshio

    2010-04-26

    A 30 kW concentrator photovoltaic power plant was constructed and has started operation with the following new technologies: A new Concentrating PhotoVoltaic (CPV) tracker developed for high wind area like Korea and Japan by Daido Steel. (The power consumption of the tracking motors was only 19.6 W, namely 0.07% of the rated power.) With improved optics that reduce the mismatch losses associated with optical aberrations, an efficiency of 25.8% was achieved under standard testing conditions (STC) even in a large 23.8 m(2) array size. A rapid installation sequence was developed. It was designed for long-term power supply to a local sewage center. Peak power corresponds to 10% of the demand. As a result, the system performance ratio was 0.87, and the capacity factor was 11.7%. The energy generation per rated power was 1,020 kWh/kWp. While it is true that CPV systems perform better in dry and high irradiance areas, our 30 kW system installed in a cloudy area like Japan, showed satisfactory performance.

  15. 30 kW concentrator photovoltaic system using dome-shaped Fresnel lenses.

    PubMed

    Araki, Kenji; Yano, Taizo; Kuroda, Yoshio

    2010-04-26

    A 30 kW concentrator photovoltaic power plant was constructed and has started operation with the following new technologies: A new Concentrating PhotoVoltaic (CPV) tracker developed for high wind area like Korea and Japan by Daido Steel. (The power consumption of the tracking motors was only 19.6 W, namely 0.07% of the rated power.) With improved optics that reduce the mismatch losses associated with optical aberrations, an efficiency of 25.8% was achieved under standard testing conditions (STC) even in a large 23.8 m2 array size. A rapid installation sequence was developed. It was designed for long-term power supply to a local sewage center. Peak power corresponds to 10% of the demand. As a result, the system performance ratio was 0.87, and the capacity factor was 11.7%. The energy generation per rated power was 1,020 kWh/kWp. While it is true that CPV systems perform better in dry and high irradiance areas, our 30 kW system installed in a cloudy area like Japan, showed satisfactory performance.

  16. Advancement of the Wide-angle JEM-EUSO Optical System with Holographic and Fresnel Lenses

    NASA Technical Reports Server (NTRS)

    Takizawa, Y.; Adams, J.H.

    2007-01-01

    JEM-EUSO is a space mission to observe extremely high-energy cosmic rays, evolved from the previous design studies of EUSO. It is adjusted for the Japan Experiment Module (JEM) of the International Space Station (ISS). JEM-EUSO uses a wide-angle refractive telescope in near-ultraviolet wavelength region to observe from ISS the time-and-space-resolved atmospheric fluorescence images of the extensive air showers. The JEM-EUSO optics is re-designed after the ESA-Phase A studies to upgrade the light-collecting-power by using a new material CYTOP, and its overall light-collecting power is about 1.5 times higher than the ESA-Phase A baseline optics. We describe in this paper an optimized optics design that maximizes the sensitivity of JEM-EUSO, and the results of the optics manufacturing tests.

  17. Weak lensing and cosmology

    NASA Astrophysics Data System (ADS)

    Lombardi, Marco; Bertin, Giuseppe

    1999-02-01

    Recently, it has been shown that it is possible to reconstruct the projected mass distribution of a cluster from weak lensing provided that both the geometry of the universe and the probability distribution of galaxy redshifts are known; actually, when additional photometric data are taken to be available, the galaxy redshift distribution could be determined jointly with the cluster mass from the weak lensing analysis. In this paper we develop, in the spirit of a ``thought experiment,'' a method to constrain the geometry of the universe from weak lensing, provided that the redshifts of the source galaxies are measured. The quantitative limits and merits of the method are discussed analytically and with a set of simulations, in relation to point estimation, interval estimation, and test of hypotheses for homogeneous Friedmann-Lema\\^\\i tre models. The constraints turn out to be significant when a few thousand source galaxies are used.

  18. Contact Lenses in the Laboratory.

    ERIC Educational Resources Information Center

    Kingston, David W.

    1981-01-01

    Summarizes results of a three-item questionnaire returned by 43 Michigan institutions expressing views on wearing contact lenses in chemical laboratories. Questions focused on eye protection, type of protection, and use of contact lenses. (SK)

  19. Gravitational lensing of gravitational wave

    NASA Astrophysics Data System (ADS)

    Kei Wong, Wang; Ng, Kwan Yeung

    2017-01-01

    Gravitational lensing phenomena are widespread in electromagnetic astrophysics, and in principle may also be uncovered with gravitational waves. We examine gravitational wave events lensed by elliptical galaxies in the limit of geometric optics, where we expect to see multiple signals from the same event with different arrival times and amplitudes. By using mass functions for compact binaries from population-synthesis simulations and a lensing probability calculated from Planck data, we estimate the rate of lensed signals for future gravitational wave missions.

  20. Radiation Blocking Lenses

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Biomedical Optical Company of America's (BOCA) suntiger lenses, similar in principle to natural filters in the eyes of hawks and eagles, bar 99 percent of potentially harmful wavelengths, while allowing visually useful colors of light (red, orange, green) to pass through. They also improve visual acuity, night vision and haze or fog visibility. The lenses evolved from work done by James B. Stephens and Dr. Charles G. Miller of the Jet Propulsion Laboratory. They developed a formula and produced a commercial welding curtain that absorbs, filters, and scatters light. This research led to protective glasses now used by dentists, workers in hazardous environments, CRT operators and skiers.

  1. Weak lensing corrections to tSZ-lensing cross correlation

    SciTech Connect

    Tröster, Tilman; Waerbeke, Ludovic Van E-mail: waerbeke@phas.ubc.ca

    2014-11-01

    The cross correlation between the thermal Sunyaev-Zeldovich (tSZ) effect and gravitational lensing in wide field has recently been measured. It can be used to probe the distribution of the diffuse gas in large scale structure, as well as inform us about the missing baryons. As for any lensing-based quantity, higher order lensing effects can potentially affect the signal. Here, we extend previous higher order lensing calculations to the case of tSZ-lensing cross correlations. We derive terms analogous to corrections due to the Born approximation, lens-lens coupling, and reduced shear up to order ℓ ∼> 3000.

  2. Rigid lenses: an overview.

    PubMed

    Bayshore, C A

    1979-03-01

    New gas permeable rigid contact lens materials, by allowing direct transmission of oxygen, provide significant advantages over PMMA. Edema resulting from oxygen deprivation with PMMA lenses is eliminated and comfort is increased. Three types of gas permeable materials are described: CAB, silicone, and a combination of CAB and silicone.

  3. Light-Weight Silver Plating Foam and Carbon Nanotube Hybridized Epoxy Composite Foams with Exceptional Conductivity and Electromagnetic Shielding Property.

    PubMed

    Xu, Yu; Li, Ying; Hua, Wei; Zhang, Aiming; Bao, Jianjun

    2016-09-14

    Herein, light-weight and exceptionally conductive epoxy composite foams were innovatively fabricated for electromagnetic interference (EMI) shielding applications using multiwalled carbon nanotubes (MWCNTs) and 3D silver-coated melamine foam (SF) as conductive frameworks. A novel and nontraditional polymer microsphere was used to reduce the material density. The preformed, highly porous, and electrically conductive SF provided channels for fast electron transport. The MWCNTs were used to offset the decrease in conductive pathways due to the crystal defects of the silver layer and the insulating epoxy resin. Consequently, an exceptional conductivity of 253.4 S m(-1), a remarkable EMI shielding effectiveness of above 68 dB at 0.05-18 GHz, and a thermal conductivity of 0.305 W mK(-1) were achieved in these novel foams employing only 2 wt % of MWCNTs and 3.7 wt % of silver due to the synergistic effects that originated in the MWCNT and SF. These parameters are substantially higher than that achieved for the foam containing 2 wt % MWCNTs. Also, the SF exhibited little weakening in the foamability of the epoxy blends and the compression properties of resulting foams. All the results indicated that this effort provided a novel, simple, low-cost, and easily industrialized concept for fabricating light-weight, high-strength epoxy composite foams for high-performance EMI shielding applications.

  4. Optical modeling of Fresnel zoneplate microscopes.

    PubMed

    Naulleau, Patrick P; Mochi, Iacopo; Goldberg, Kenneth A

    2011-07-10

    Defect free masks remain one of the most significant challenges facing the commercialization of extreme ultraviolet (EUV) lithography. Progress on this front requires high-performance wavelength-specific metrology of EUV masks, including high-resolution and aerial-image microscopy performed near the 13.5 nm wavelength. Arguably the most cost-effective and rapid path to proliferating this capability is through the development of Fresnel zoneplate-based microscopes. Given the relative obscurity of such systems, however, modeling tools are not necessarily optimized to deal with them and their imaging properties are poorly understood. Here we present a modeling methodology to analyze zoneplate microscopes based on commercially available optical modeling software and use the technique to investigate the imaging performance of an off-axis EUV microscope design. The modeling predicts that superior performance can be achieved by tilting the zoneplate, making it perpendicular to the chief ray at the center of the field, while designing the zoneplate to explicitly work in that tilted plane. Although the examples presented here are in the realm of EUV mask inspection, the methods described and analysis results are broadly applicable to zoneplate microscopes in general, including full-field soft-x-ray microscopes routinely used in the synchrotron community.

  5. Optical modeling of Fresnel zoneplate microscopes

    SciTech Connect

    Naulleau, Patrick P.; Mochi, Iacopo; Goldberg, Kenneth A.

    2011-07-10

    Defect free masks remain one of the most significant challenges facing the commercialization of extreme ultraviolet (EUV) lithography. Progress on this front requires high-performance wavelength-specific metrology of EUV masks, including high-resolution and aerial-image microscopy performed near the 13.5 nm wavelength. Arguably the most cost-effective and rapid path to proliferating this capability is through the development of Fresnel zoneplate-based microscopes. Given the relative obscurity of such systems, however, modeling tools are not necessarily optimized to deal with them and their imaging properties are poorly understood. Here we present a modeling methodology to analyze zoneplate microscopes based on commercially available optical modeling software and use the technique to investigate the imaging performance of an off-axis EUV microscope design. The modeling predicts that superior performance can be achieved by tilting the zoneplate, making it perpendicular to the chief ray at the center of the field, while designing the zoneplate to explicitly work in that tilted plane. Although the examples presented here are in the realm of EUV mask inspection, the methods described and analysis results are broadly applicable to zoneplate microscopes in general, including full-field soft-x-ray microscopes routinely used in the synchrotron community.

  6. Variable Phase for Fresnel Zone Plates

    NASA Astrophysics Data System (ADS)

    Webb, George W.

    2004-03-01

    It is not widely known that there is a free parameter in the usual design of zone plates. An earlier work treated the radius of the central Fresnel zone as the free parameter and investigated the effects of its variation numerically [1]. It is possible instead to treat the choice of reference phase in the design of a zone plate as the free parameter [2]. The standard zone plate construction assumes a specific choice for this phase which, however, can be chosen to have any value between 0^o and 360^o. Here we present analysis and measurements on zone plates for 39 GHz radiation with reference phase varied from 0^o to 360^o. When the reference phase is varied, measurements show that the phase of the focused beam is varied in a nearly linear fashion through 360^o with only small changes in beam amplitude. It is concluded that reference phase is an inherent and useful property of zone plates. 1) I.V. Minin and O.V. Minin, Sov. J. Quantum Electron. derline 20, 198 (1990). I thank I.V. Minin for calling this work to my attention. 2) G.W. Webb, Proc. 2003 Antenna Applications Symposium, Allerton Park, Monticello, IL, September 15-17, 2003 and arXiv:physics/0303002 28 Feb 2003.

  7. Optical modeling of Fresnel zoneplate microscopes

    SciTech Connect

    Naulleau, Patrick; Mochi, Iacopo; Goldberg, Kenneth A.

    2011-04-06

    Defect free masks remain one of the most significant challenges facing the commercialization of extreme ultraviolet (EUV) lithography. Progress on this front requires high-performance wavelength-specific metrology of EUV masks, including high-resolution and aerial-image microscopy performed near the 13.5 nm wavelength. Arguably the most cost-effective and rapid path to proliferating this capability is through the development of Fresnel zoneplate-based microscopes. Given the relative obscurity of such systems, however, modeling tools are not necessarily optimized to deal with them and their imaging properties are poorly understood. Here we present a modeling methodology to analyze zoneplate microscopes based on commercially available optical modeling software and use the technique to investigate the imaging performance of an off-axis EUV microscope design. The modeling predicts that superior performance can be achieved by tilting the zoneplate, making it perpendicular to the chief ray at the center of the field, while designing the zoneplate to explicitly work in that tilted plane. Although the examples presented here are in the realm of EUV mask inspection, the methods described and analysis results are broadly applicable to zoneplate microscopes in general, including full-field soft-x-ray microscopes rou tinely used in the synchrotron community.

  8. Obituary--rigid contact lenses.

    PubMed

    Efron, Nathan

    2010-10-01

    Scleral and corneal rigid lenses represented 100 per cent of the contact lens market immediately prior to the invention of soft lenses in the mid-1960s. In the United Kingdom today, rigid lenses comprise 2 per cent of all new lens fits. Low rates of rigid lens fitting are also apparent in 27 other countries which have recently been surveyed. Thus, the 1998 prediction of the author that rigid lenses--also referred to as 'rigid gas permeable' (RGP) lenses or 'gas permeable' (GP) lenses--would be obsolete by the year 2010 has essentially turned out to be correct. In this obituary, the author offers 10 reasons for the demise of rigid lens fitting: initial rigid lens discomfort; intractable rigid lens-induced corneal and lid pathology; extensive soft lens advertising; superior soft lens fitting logistics; lack of rigid lens training opportunities; redundancy of the rigid lens 'problem solver' function; improved soft toric and bifocal/varifocal lenses; limited uptake of orthokeratology; lack of investment in rigid lenses; and the emergence of aberration control soft lenses. Rigid lenses are now being fitted by a minority of practitioners with specialist skills/training. Certainly, rigid lenses can no longer be considered as a mainstream form of contact lens correction. May their dear souls (bulk properties) rest in peace.

  9. Design of a solar collector system formed by a Fresnel lens and a CEC coupled to plastic fibers

    NASA Astrophysics Data System (ADS)

    Viera-González, Perla M.; Sánchez-Guerrero, Guillermo E.; Ceballos-Herrera, Daniel E.; Selvas-Aguilar, Romeo

    2015-08-01

    Among the main challenges for systems based in solar concentrators and plastic optical fibers (POF) the accuracy needed for the solar tracking is founded. One approach to overcome these requirements is increasing acceptance angle of the components, usually by secondary optical elements (SOE), however this technique is effective for photovoltaic applications but it has not been analyzed for systems coupled to POFs for indoor illumination. On this subject, it is presented a numerical analysis of a solar collector assembled by a Fresnel lens as primary optical element (POE) combined with a compound elliptical concentrator (CEC) coupled to POF in order to compare its performance under incidence angle direction and also to show a trade-off analysis for two different Fresnel lens shapes, imaging and nonimaging, used in the collector system. The description of the Fresnel lenses and its designs are included, in addition to the focal areas with space and angular distribution profiles considering the optimal alignment with the source and maximum permissible incident angle for each case. For both systems the coupling between the optical components is analyzed and the total performance is calculated, having as result its comparison for indoor illumination. In both cases, the systems have better performance increasing the final output power, but the angular tolerance only was improved for the system with nonimaging concentrator that had an efficiency over 80% with acceptance angles 𝜃𝑖 ≤ 2° and, the system integrated by the imaging lens, presented an efficiency ratio over 75% for acceptance angles 𝜃𝑖 ≤ 0.7°.

  10. High-resolution quasi-monochromatic X-ray imaging using a Fresnel phase zone plate and a multilayer mirror.

    PubMed

    Do, A; Troussel, Ph; Baton, S D; Dervieux, V; Gontier, D; Lecherbourg, L; Loupias, B; Obst, L; Pérez, F; Renaudin, P; Reverdin, Ch; Rubbelynck, C; Stemmler, Ph; Soullié, G

    2017-01-01

    High-resolution, high-sensitivity X-ray imaging is a real challenge in laser plasma diagnostic to attain reliable data in high-energy density plasma experiments. In this context, ultra-high-intensity lasers generate hot and dense plasma but only in a small volume. An experiment has been performed at the LULI2000 laser facility to diagnose such plasma conditions from thermal spectroscopic data. To image the emission zone plasma's Al Heβ, a Fresnel-lens-based X-ray imager has been developed. It features a 846 μm-diameter Fresnel Phase Zone Plate (FPZP) and a Pd/B4C multilayer mirror (thickness d = 5.1 nm). This association can be used between 1500 eV and 2100 eV. The FPZP's efficiency was measured on a synchrotron facility (SOLEIL) and its spatial resolution in a laser facility (EQUINOX). The mirror reflectivity was measured on the synchrotron facility BESSY II. With experimental conditions, the system resolution reaches 3.8 ± 0.6 μm with an adequate efficiency in the 1800 eV-1900 eV energy range with a solid angle of 9 × 10(-6) sr. Consequently, a FPZP is an excellent optics setup for high-resolution quasi-monochromatic X-ray imaging and provides a good collection angle. Bragg-Fresnel lenses, based on the principle of FPZP and mirrors, are currently designed for an X-ray imager at the Laser MégaJoule facility.

  11. Weak lensing by voids in modified lensing potentials

    SciTech Connect

    Barreira, Alexandre; Cautun, Marius; Li, Baojiu; Baugh, Carlton M.; Pascoli, Silvia E-mail: m.c.cautun@durham.ac.uk E-mail: c.m.baugh@durham.ac.uk

    2015-08-01

    We study lensing by voids in Cubic Galileon and Nonlocal gravity cosmologies, which are examples of theories of gravity that modify the lensing potential. We find voids in the dark matter and halo density fields of N-body simulations and compute their lensing signal analytically from the void density profiles, which we show are well fit by a simple analytical formula. In the Cubic Galileon model, the modifications to gravity inside voids are not screened and they approximately double the size of the lensing effects compared to GR. The difference is largely determined by the direct effects of the fifth force on lensing and less so by the modified density profiles. For this model, we also discuss the subtle impact on the force and lensing calculations caused by the screening effects of haloes that exist in and around voids. In the Nonlocal model, the impact of the modified density profiles and the direct modifications to lensing are comparable, but they boost the lensing signal by only ≈ 10%, compared with that of GR. Overall, our results suggest that lensing by voids is a promising tool to test models of gravity that modify lensing.

  12. Toward the diffraction limit with transmissive x-ray lenses in astronomy.

    PubMed

    Braig, Christoph; Predehl, Peter

    2012-07-10

    We develop an analytical approach to refractive, blazed diffractive, and achromatic x-ray lenses of scalable dimensions for energies from 1 to 20 keV. Based on the parabolic wave equation, their wideband imaging properties are compared and optimized for a given spectral range. Low-Z lens materials for massive cores and rugged alternatives, such as polycarbonate or Si for flat Fresnel components, are investigated with respect to their suitability for diffraction-limited high-energy astronomy. Properly designed "hybrid" combinations can serve as an approach to x-ray telescopes with an enhanced efficiency throughout the whole considered band, nearly regardless of their inherent absorption.

  13. The mini-dome Fresnel lens photovoltaic concentrator array - Current status of component and prototype panel testing

    NASA Technical Reports Server (NTRS)

    Piszczor, M. F.; Swartz, C. K.; O'Neill, M. J.; Mcdanal, A. J.; Fraas, L. M.

    1990-01-01

    NASA Lewis and ENTECH have been developing a high-efficiency, lightweight space photovoltaic concentrator array. The emphasis of the program has shifted to fabrication and testing of the minidome Fresnel lens and other array components. Protototype lenses have been tested for optical efficiency, with results around 90 percent, and tracking error performance. The results of these tests have been very consistent with the predicted analytical performance. Work has also progressed in the fabrication of the array support structure. Recent advances in 30 percent efficient stacked cell technology will have a significant effect on the array performance. It is concluded that near-term array performance goals of 300 W/sq m and 100 W/kg are feasible.

  14. Assembly and testing of a 1.8 by 3.7 meter Fresnel lens solar concentrator

    NASA Technical Reports Server (NTRS)

    Robertson, J. E.

    1977-01-01

    A project was initiated to establish a technical data base on line focusing acrylic Fresnel lenses for use in a solar collector system that could generate temperatures in the range of 200 C to 370 C. The effort was originally directed toward electric power generation in the 100 to 10,000 kWe range using a distributed collector approach. However, as the program progressed, it centered on the development of a concentrator/collector subsystem concept that could meet the general requirement of thermal delivery within the 200 C to 370 C range. The expanded list of possible applications includes commercial heating/cooling and industrial process heat as well as electric power generation.

  15. Multilayer Fresnel zone plates for high energy radiation resolve 21 nm features at 1.2 keV.

    PubMed

    Keskinbora, Kahraman; Robisch, Anna-Lena; Mayer, Marcel; Sanli, Umut T; Grévent, Corinne; Wolter, Christian; Weigand, Markus; Szeghalmi, Adriana; Knez, Mato; Salditt, Tim; Schütz, Gisela

    2014-07-28

    X-ray microscopy is a successful technique with applications in several key fields. Fresnel zone plates (FZPs) have been the optical elements driving its success, especially in the soft X-ray range. However, focusing of hard X-rays via FZPs remains a challenge. It is demonstrated here, that two multilayer type FZPs, delivered from the same multilayer deposit, focus both hard and soft X-rays with high fidelity. The results prove that these lenses can achieve at least 21 nm half-pitch resolution at 1.2 keV demonstrated by direct imaging, and sub-30 nm FWHM (full-pitch) resolution at 7.9 keV, deduced from autocorrelation analysis. Reported FZPs had more than 10% diffraction efficiency near 1.5 keV.

  16. An analytical and experimental investigation of a 1.8 by 3.7 meter Fresnel lens solar concentrator

    NASA Technical Reports Server (NTRS)

    Hastings, L. J.; Allums, S. L.; Jensen, W. S.

    1977-01-01

    Line-focusing acrylic Fresnel lenses with application potential in the 200 to 370 C range are being analytically and experimentally evaluated. Investigations previously conducted with a 56 cm wide lens have been extended by the present study to experimentation/analyses with a 1.8 by 3.7 m lens. A measured peak concentration ratio of 64 with 90 percent of the transmitted energy focused into a 5.0 cm width was achieved. A peak concentration of 61 and a 90 percent target width of 4.5 cm were analytically computed. The experimental and analytical lens transmittance was 81 percent and 86 percent, respectively. The lens also was interfaced with a receiver assembly and operated in the collection mode. The collection efficiency ranged from 42 percent at 100 C to 26 percent at 300 C.

  17. Learning unit: Thin lenses

    NASA Astrophysics Data System (ADS)

    Nita, L.-S.

    2012-04-01

    Learning unit: Thin lenses "Why objects seen through lenses are sometimes upright and sometimes reversed" Nita Laura Simona National College of Arts and Crafts "Constantin Brancusi", Craiova, Romania 1. GEOMETRIC OPTICS. 13 hours Introduction (models, axioms, principles, conventions) 1. Thin lenses (Types of lenses. Defining elements. Path of light rays through lenses. Image formation. Required physical quantities. Lens formulas). 2. Lens systems (Non-collated lenses. Focalless systems). 3. Human eye (Functioning as an optical system. Sight defects and their corrections). 4. Optical instruments (Characteristics exemplified by a magnifying glass. Paths of light rays through a simplified photo camera. Path of light rays through a classical microscope) (Physics curriculum for the IXth grade/ 2011). This scenario exposes a learning unit based on experimental sequences (defining specific competencies), as a succession of lessons started by noticing a problem whose solution assumes the setup of an experiment under laboratory conditions. Progressive learning of theme objectives are realised with sequential experimental steps. The central cognitive process is the induction or the generalization (development of new knowledge based on observation of examples or counterexamples of the concept to be learnt). Pupil interest in theme objectives is triggered by problem-situations, for example: "In order to better see small objects I need a magnifying glass. But when using a magnifier, small object images are sometimes seen upright and sometimes seen reversed!" Along the way, pupils' reasoning will converge to the idea: "The image of an object through a lens depends on the relative distances among object, lens, and observer". Associated learning model: EXPERIMENT Specific competencies: derived from the experiment model, in agreement with the following learning unit steps I. Evoking - Anticipation: Size of the problem, formulation of hypotheses and planning of experiment. II

  18. Simulation of the Vacuum Assisted Resin Transfer Molding (VARTM) process and the development of light-weight composite bridging

    NASA Astrophysics Data System (ADS)

    Robinson, Marc J.

    A continued desire for increased mobility in the aftermath of natural disasters, or on the battlefield, has lead to the need for improved light-weight bridging solutions. This research investigates the development of a carbon/epoxy composite bridging system to meet the needs for light-weight bridging. The research focuses on two main topics. The first topic is that of processing composite structures and the second is the design and testing of these structures. In recent years the Vacuum Assisted Resin Transfer Molding (VARTM) process has become recognized as a low-cost manufacturing alternative for large Fiber Reinforced Polymer (FRP) composite structures for civil, military, and aerospace applications. The success of the VARTM process (complete wet-out) is very sensitive to the resin injection strategy used and the proper placement of flow distribution materials and inlet and vacuum ports. Predicting the flow front pattern, the time required for infusing a part with resin, and the time required to bleed excess resin at the end of filling, is critical to ensure that the part will become completely impregnated and desired fiber volume fractions achieved prior to the resin gelling (initiation of cure). In order to eliminate costly trial and error experiments to determine the optimal infusion strategy, this research presents a simulation model which considers in-plane flow as well as flow through the thickness of the preform. In addition to resin filling, the current model is able to simulate the bleeding of resin at the end of filling to predict the required bleeding time to reach desired fiber volume fractions for the final part. In addition to processing, the second portion of the dissertation investigates the design and testing of composite bridge deck sections which also serve as short-span bridging for gaps up to 4 m in length. The research focuses on the design of a light-weight core material for bridge decking as well as proof loading of short-span bridge

  19. Analysis on the alignment errors of segmented Fresnel lens

    NASA Astrophysics Data System (ADS)

    Zhou, Xudong; Wu, Shibin; Yang, Wei; Wang, Lihua

    2014-09-01

    Stitching Fresnel lens are designed for the application in the micro-focus X-ray, but splicing errors between sub-apertures will affect optical performance of the entire mirror. The offset error tolerance of different degrees of freedom between the sub-apertures are analyzed theoretically according to the wave-front aberration theory and with the Rayleigh criterion as evaluation criteria, and then validate the correctness of the theory using simulation software of ZEMAX. The results show that Z-axis piston error tolerance and translation error tolerance of XY axis increases with the increasing F-number of stitching Fresnel lens, and tilt error tolerance of XY axis decreases with increasing diameter. The results provide a theoretical basis and guidance for the design, detection and alignment of stitching Fresnel lens.

  20. Tolerancing panoramic lenses

    NASA Astrophysics Data System (ADS)

    Parent, Jocelyn; Thibault, Simon

    2009-08-01

    Tolerancing a lens is a basic procedure in lens design. It consists in first defining an appropriate set of tolerances for the lens, then in adding compensators with their allowable ranges and finally in selecting an appropriate quality criterion (MTF, RMS spot size, wavefront error, boresight error...) for the given application. The procedure is straightforward for standard optical systems. However, it becomes more complex when tolerancing very wide angle lenses (larger than 150 degrees). With a large field of view, issues such as severe off-axis pupil shift, considerable distortion and low relative illumination must be addressed. The pupil shift affects the raytrace as some rays can no longer be traced properly. For high resolution imagers, particularly for robotic and security applications, the image footprint is most critical in order to limit or avoid complex calibration procedures. We studied various wide angle lenses and concluded that most of the distortion comes from the front surface of the lens. Consequently, any variation of the front surface will greatly affect the image footprint. In this paper, we study the effects on the image footprint of slightly modifying the front surface of four different lenses: a simple double-gauss for comparison, a fisheye lens, a catadioptric system (omnidirectional lens) and a Panomorph lens. We also present a method to analyze variations of the image footprint. Our analysis shows that for wide angle lenses, on which the entrance pupil is much smaller than the front surface, irregularities (amplitude, slope and location) are critical on both aspherical and spherical front surfaces to predict the image footprint variation for high resolution cameras. Finally, we present how the entrance pupil varies (location, size) with the field of view for these optical systems.

  1. Dispersion corrections of the copper K edge measured by Fresnel diffraction.

    PubMed

    Lee, Wah-Keat; Cloetens, Peter; Schlenker, Michel

    2004-01-01

    Dispersion corrections to the atomic scattering factors for the copper K edge have been measured by a new technique, Fresnel diffraction. Fresnel diffraction fringes were measured at several sample-detector distances as a function of energy across the copper K-absorption edge. The dispersion corrections were obtained from optimizing a least-squares fit of Fresnel fringe simulations to the measured data.

  2. Structural Verification of the Space Shuttle's External Tank Super LightWeight Design: A Lesson in Innovation

    NASA Technical Reports Server (NTRS)

    Otte, Neil

    1997-01-01

    The Super LightWeight Tank (SLWT) team was tasked with a daunting challenge from the outset: boost the payload capability of the Shuttle System by safely removing 7500 lbs. from the existing 65,400 lb. External Tank (ET). Tools they had to work with included a promising new Aluminum Lithium alloy, the concept of a more efficient structural configuration for the Liquid Hydrogen (LH2) tank, and a highly successful, mature Light Weight Tank (LWT) program. The 44 month schedule which the SLWT team was given for the task was ambitious by any measure. During this time the team had to not only design, build, and verify the new tank, but they also had to move a material from the early stages of development to maturity. The aluminum lithium alloy showed great promise, with an approximately 29% increase in yield strength, 15% increase in ultimate strength, 5 deg/O increase in modulus and 5 deg/O decrease in density when compared to the current 2219 alloy. But processes had to be developed and brought under control, manufacturing techniques perfected, properties characterized, and design allowable generated. Because of the schedule constraint, this material development activity had to occur in parallel with design and manufacturing. Initial design was performed using design allowable believed to be achievable with the Aluminum Lithium alloy system, but based on limited test data. Preliminary structural development tests were performed with material still in the process of iteration. This parallel path approach posed obvious challenges and risks, but also allowed a unique opportunity for interaction between the structures and materials disciplines in the formulation of the material.

  3. Fresnel prisms and their effects on visual acuity and binocularity.

    PubMed Central

    Véronneau-Troutman, S

    1978-01-01

    1. The visual acuity with the Fresnel membrane prism is significantly less than that with the conventional prism of the same power for all prism powers from 12 delta through 30 delata at distance and from 15 delta through 30 delta at near. 2. The difference in the visual acuity between base up and base down, and between base in and base out, is not significantly different for either the Fresnel membrane prism or for the conventional prism. 3. For both Fresnel membrane prism and the conventional prism, the visual acuity when looking straight ahead. 4. Using Fresnel membrane prisms of the same power from different lots, the visual acuity varied significantly. The 30 delta prism caused the widest range in visual acuity. 5. When normal subjects are fitted with the higher powers of the Fresnel membrane prism, fusion and stereopsis are disrupted to such an extent that the use of this device to restore or to improve binocular vision in cases with large-angle deviations is seriously questioned. 6. Moreover, the disruption of fusion and stereopsis is abrupt and severe and does not parallel the decrease in visual acuity. The severely reduced ability to maintain fusion may be related to the optical aberrations, which, in turn, may be due to the molding process and the polyvinyl chloride molding material. 7. Through the flexibility of the membrane prism is a definite advantage, because of its proclivity to reduce visual acuity and increase aberrations its prescription for adults often must be limited to only one eye. 8. For the same reasons in the young child with binocular vision problems, the membrane prism presently available should be prescribed over both eyes only in powers less than 20 delta. When the membrane prism is to be used as a partial occluder (over one eye only), any power can be used. 9. The new Fresnel "hard" prism reduces visual acuity minimally and rarely disrupts binocularity, thus increasing the potential for prismotherapy to establish binocularity. This

  4. Evolutionary algorithm for optimization of nonimaging Fresnel lens geometry.

    PubMed

    Yamada, N; Nishikawa, T

    2010-06-21

    In this study, an evolutionary algorithm (EA), which consists of genetic and immune algorithms, is introduced to design the optical geometry of a nonimaging Fresnel lens; this lens generates the uniform flux concentration required for a photovoltaic cell. Herein, a design procedure that incorporates a ray-tracing technique in the EA is described, and the validity of the design is demonstrated. The results show that the EA automatically generated a unique geometry of the Fresnel lens; the use of this geometry resulted in better uniform flux concentration with high optical efficiency.

  5. Integration of nanostructured planar diffractive lenses dedicated to near infrared detection for CMOS image sensors.

    PubMed

    Lopez, Thomas; Massenot, Sébastien; Estribeau, Magali; Magnan, Pierre; Pardo, Fabrice; Pelouard, Jean-Luc

    2016-04-18

    This paper deals with the integration of metallic and dielectric nanostructured planar lenses into a pixel from a silicon based CMOS image sensor, for a monochromatic application at 1.064 μm. The first is a Plasmonic Lens, based on the phase delay through nanoslits, which has been found to be hardly compatible with current CMOS technology and exhibits a notable metallic absorption. The second is a dielectric Phase-Fresnel Lens integrated at the top of a pixel, it exhibits an Optical Efficiency (OE) improved by a few percent and an angle of view of 50°. The third one is a metallic diffractive lens integrated inside a pixel, which shows a better OE and an angle of view of 24°. The last two lenses exhibit a compatibility with a spectral band close to 1.064 μm.

  6. Pinhole diffraction holography for fabrication of high-resolution Fresnel zone plates.

    PubMed

    Sarkar, Sankha S; Solak, Harun H; David, Christian; van der Veen, J Friso

    2014-01-27

    Fresnel zone plates (FZPs) play an essential role in high spatial resolution x-ray imaging and analysis of materials in many fields. These diffractive lenses are commonly made by serial writing techniques such as electron beam or focused ion beam lithography. Here we show that pinhole diffraction holography has potential to generate FZP patterns that are free from aberrations and imperfections that may be present in alternative fabrication techniques. In this presented method, FZPs are fabricated by recording interference pattern of a spherical wave generated by diffraction through a pinhole, illuminated with coherent plane wave at extreme ultraviolet (EUV) wavelength. Fundamental and practical issues involved in formation and recording of the interference pattern are considered. It is found that resolution of the produced FZP is directly related to the diameter of the pinhole used and the pinhole size cannot be made arbitrarily small as the transmission of EUV or x-ray light through small pinholes diminishes due to poor refractive index contrast found between materials in these spectral ranges. We also find that the practical restrictions on exposure time due to the light intensity available from current sources directly imposes a limit on the number of zones that can be printed with this method. Therefore a trade-off between the resolution and the FZP diameter exists. Overall, we find that this method can be used to fabricate aberration free FZPs down to a resolution of about 10 nm.

  7. SPT Lensing Likelihood: South Pole Telescope CMB lensing likelihood code

    NASA Astrophysics Data System (ADS)

    Feeney, Stephen M.; Peiris, Hiranya V.; Verde, Licia

    2014-11-01

    The SPT lensing likelihood code, written in Fortran90, performs a Gaussian likelihood based upon the lensing potential power spectrum using a file from CAMB (ascl:1102.026) which contains the normalization required to get the power spectrum that the likelihood call is expecting.

  8. Algorithms for Fresnel Diffraction at Rectangular and Circular Apertures

    PubMed Central

    Mielenz, Klaus D.

    1998-01-01

    This paper summarizes the theory of Fresnel diffraction by plane rectangular and circular apertures with a view toward numerical computations. Approximations found in the earlier literature, and now obsolete, have been eliminated and replaced by algorithms suitable for use on a personal computer. PMID:28009380

  9. Fresnel Diffraction Using a He-Ne Gas Laser

    ERIC Educational Resources Information Center

    Moen, Allen L.; Vander Meulen, David L.

    1970-01-01

    Describes an advanced laboratory experiment of Fresnel diffraction which uses a He-Ne gas laser as the source and a wire as the opaque diffracting strip. A photograph of the diffraction pattern is compared with the intensity diagram predicted by the Cornu spiral method. Agreement is clear and impressive, although minor differences are detectable.…

  10. Lightweight Inexpensive Ozone Lidar Telescope Using a Plastic Fresnel Lens

    NASA Technical Reports Server (NTRS)

    DeYoung, Russell J.; Notari, Anthony; Carrion, William; Pliutau, Denis

    2014-01-01

    An inexpensive lightweight ozone lidar telescope was designed, constructed and operated during an ozone lidar field campaign. This report summarizes the design parameters and performance of the plastic Fresnel lens telescope and shows the ozone lidar performance compared to Zemax calculations.

  11. Fresnel-based beamforming for low-cost portable ultrasound.

    PubMed

    Nguyen, Man Minh; Mung, Jay; Yen, Jesse T

    2011-01-01

    In this paper, we propose a modified electronic Fresnel-based beamforming method for low-cost portable ultrasound systems. This method uses a unique combination of analog and digital beamforming methods. Two versions of Fresnel beamforming are presented in this paper: 4-phase (4 different time delays or phase shifts) and 8-phase (8 different time delays or phase shifts). The advantage of this method is that a system with 4 to 8 transmit channels and 2 receive channels with a network of switches can be used to focus an array with 64 to 128 elements. The simulation and experimental results show that Fresnel beamforming image quality is comparable to traditional delay-and-sum (DAS) beamforming in terms of spatial resolution and contrast-to-noise ratio (CNR) under certain system parameters. With an f-number of 2 and 50% signal bandwidth, the experimental lateral beamwidths are 0.54, 0.67, and 0.66 mm and the axial pulse lengths are 0.50, 0.51, and 0.50 mm for DAS, 8-phase, and 4-phase Fresnel beamforming, respectively. The experimental CNRs are 4.66, 4.42, and 3.98, respectively. These experimental results are in good agreement with simulation results.

  12. Switchable Fresnel lens using polymer-stabilized liquid crystals.

    PubMed

    Fan, Yun-Hsing; Ren, Hongwen; Wu, Shin-Tson

    2003-11-17

    A switchable Fresnel zone plate lens is demonstrated using a polymer-stabilized liquid crystal. The fabrication process is relatively simple and the device can be operated below 10 volts with fast response time. Such a device works well for a linearly polarized light.

  13. The linear Fresnel lens solar concentrator: Transverse tracking error effects

    NASA Technical Reports Server (NTRS)

    Cosby, R. M.

    1977-01-01

    The solar concentration performance of a line focusing, flat base Fresnel lens in the presence of small transverse tracking errors was analyzed. Solar transmittance of the lens and focal plane imaging characteristics were evaluated. Transmission losses by reflectance and material absorption were also studied.

  14. RHIC electron lenses upgrades

    SciTech Connect

    Gu, X.; Altinbas, Z.; Bruno, D.; Binello, S.; Costanzo, M.; Drees, A.; Fischer, W.; Gassner, D. M.; Hock, J.; Hock, K.; Harvey, M.; Luo, Y.; Marusic, A.; Mi, C.; Mernick, K.; Minty, M.; Michnoff, R.; Miller, T. A.; Pikin, A. I.; Robert-Demolaize, G.; Samms, T.; Shrey, T. C.; Schoefer, V.; Tan, Y.; Than, R.; Thieberger, P.; White, S. M.

    2015-05-03

    In the Relativistic Heavy Ion Collider (RHIC) 100 GeV polarized proton run in 2015, two electron lenses were used to partially compensate for the head-on beam-beam effect for the first time. Here, we describe the design of the current electron lens, detailing the hardware modifications made after the 2014 commissioning run with heavy ions. A new electron gun with 15-mm diameter cathode is characterized. The electron beam transverse profile was measured using a YAG screen and fitted with a Gaussian distribution. During operation, the overlap of the electron and proton beams was achieved using the electron backscattering detector in conjunction with an automated orbit control program.

  15. Hollow lensing duct

    DOEpatents

    Beach, Raymond J.; Honea, Eric C.; Bibeau, Camille; Mitchell, Scott; Lang, John; Maderas, Dennis; Speth, Joel; Payne, Stephen A.

    2000-01-01

    A hollow lensing duct to condense (intensify) light using a combination of focusing using a spherical or cylindrical lens followed by reflective waveguiding. The hollow duct tapers down from a wide input side to a narrow output side, with the input side consisting of a lens that may be coated with an antireflective coating for more efficient transmission into the duct. The inside surfaces of the hollow lens duct are appropriately coated to be reflective, preventing light from escaping by reflection as it travels along the duct (reflective waveguiding). The hollow duct has various applications for intensifying light, such as in the coupling of diode array pump light to solid state lasing materials.

  16. Light weight phosphate cements

    DOEpatents

    Wagh, Arun S.; Natarajan, Ramkumar,; Kahn, David

    2010-03-09

    A sealant having a specific gravity in the range of from about 0.7 to about 1.6 for heavy oil and/or coal bed methane fields is disclosed. The sealant has a binder including an oxide or hydroxide of Al or of Fe and a phosphoric acid solution. The binder may have MgO or an oxide of Fe and/or an acid phosphate. The binder is present from about 20 to about 50% by weight of the sealant with a lightweight additive present in the range of from about 1 to about 10% by weight of said sealant, a filler, and water sufficient to provide chemically bound water present in the range of from about 9 to about 36% by weight of the sealant when set. A porous ceramic is also disclosed.

  17. Halo-lensing or Self-lensing? Locating the MACHO Lenses

    NASA Astrophysics Data System (ADS)

    Nelson, C. A.; Cook, K. H.; Popowski, P.; Drake, A. J.; Marshall, S. L.; Griest, K.; Vandehei, T.; Alcock, C.; Allsman, R. A.; Axelrod, T. S.; Freeman, K. C.; Peterson, B. A.; Alves, D. R.; Becker, A. C.; Stubbs, C. W.; Tomaney, A. B.; Bennett, D. P.; Geha, M.; Lehner, M. J.; Minniti, D.; Pratt, M. R.; Quinn, P. J.; Sutherland, W.; Welch, D.; MACHO Collaboration

    2000-12-01

    There are two principle geometrical arrangements which may explain Large Magellanic Cloud (LMC) microlensing: a) halo-lensing, in which the lensed object is part of the Milky Way galactic halo and b) self-lensing, in which the lensed object is part of the LMC. Self-lensing in turn may be broken into two categories: LMC-LMC self-lensing, in which both the source and the lens reside in the LMC and background self-lensing, in which the lens is a star in the LMC and the source star is drawn from some population behind the LMC. Models suggest the contribution of LMC-LMC self-lensing is small, so the nature of LMC microlensing may be estimated from the location of the microlensing source stars. If the source stars are in the LMC then microlensing is dominated by halo-lensing; conversely if the source stars are located behind the LMC then microlensing is dominated by self-lensing. Since background populations reside behind the LMC, we expect them to be both redder and fainter then the average population of the LMC. We attempt to determine if the MACHO source stars come from such a background population by comparing the HST color-magnitude diagram (CMD) of source stars to the CMD of the average population of the LMC and looking for the effects of extra reddening and extinction. The microlensing source stars are identified by deriving accurate centroids in the ground-based MACHO images using difference image analysis (DIA) and then transforming the DIA coordinates to the HST frame. Preliminary results suggest that halo-lensing accounts for ≳ 40% of the observed microlensing results. Support provided by NASA, DOE, NSF and NPSC.

  18. Optics of progressive addition lenses.

    PubMed

    Sheedy, J E; Buri, M; Bailey, I L; Azus, J; Borish, I M

    1987-02-01

    The optical characteristics of the major progressive addition lenses were measured using an automated lensometer with a specially designed lens holder to simulate eye rotation. Measurements were made every 3 degrees (about 1.5 mm) and graphs of isospherical equivalent lines and isocylinder lines were developed. Generally the near zone of these lenses is narrower and lower than in bifocal or trifocal lenses. Distinct differences exist between the various progressive lenses. The width of the near zone, rate of power progression, amount of unwanted cylinder (level with the distance center), and clarity of the distance zone are compared for the various lenses. The optical measurements demonstrate an apparent trade-off between the size of the cylinder-free area of the lens and the amount of the cylinder.

  19. RBioCloud: A Light-Weight Framework for Bioconductor and R-based Jobs on the Cloud.

    PubMed

    Varghese, Blesson; Patel, Ishan; Barker, Adam

    2015-01-01

    Large-scale ad hoc analytics of genomic data is popular using the R-programming language supported by over 700 software packages provided by Bioconductor. More recently, analytical jobs are benefitting from on-demand computing and storage, their scalability and their low maintenance cost, all of which are offered by the cloud. While biologists and bioinformaticists can take an analytical job and execute it on their personal workstations, it remains challenging to seamlessly execute the job on the cloud infrastructure without extensive knowledge of the cloud dashboard. How analytical jobs can not only with minimum effort be executed on the cloud, but also how both the resources and data required by the job can be managed is explored in this paper. An open-source light-weight framework for executing R-scripts using Bioconductor packages, referred to as `RBioCloud', is designed and developed. RBioCloud offers a set of simple command-line tools for managing the cloud resources, the data and the execution of the job. Three biological test cases validate the feasibility of RBioCloud. The framework is available from http://www.rbiocloud.com.

  20. Thermal Response Simulation of Ultra Light Weight Phenolic Carbon Ablator by the Use of the Ablation Analysis Code

    NASA Astrophysics Data System (ADS)

    Kato, Sumio; Okuyama, Keiichi; Gibo, Kenta; Miyagi, Takuma; Suzuki, Toshiyuki; Fujita, Kazuhisa; Sakai, Takeharu; Nishio, Seiji; Watanabe, Akihiro

    A space vehicle which undergoes the atmospheric re-entry or a planetary entry needs the heat shield system to protect inner equipments against severe aerodynamic heating environments. Charring ablator is usually used for the heat shield system. In order to design the heat shield system, it is necessary to predict the thermal behavior under aerodynamic heating by ablation analysis. A computer code for charring ablation and thermal response analysis is newly developed for simulation of one-dimensional transient thermal behavior of charring ablation materials. The mathematical model for the charring ablation including basic equation and computational method of ablation analysis is briefly described. A new ultra light weight phenolic carbon ablator called LATS (Lightweight Ablator series for Transfer vehicle) was recently developed. Arc-heated tests of the LATS ablator were carried out and measured results of the temperature response and surface mass loss are compared with the simulation results of the ablation analysis program. The agreement between the results of simulation and measurement is found to be good. It is also found that the mathematical model used in the ablation code can be applied to the ablation analysis of the low density LATS ablator.

  1. Light-Weight Radioisotope Heater Unit Final Safety Analysis Report (LWRHU FSAR): Volume 3, Nuclear Risk Analysis Document

    SciTech Connect

    Not Available

    1988-11-30

    The Light-Weight Radioisotope Heater Unit (LWRHU) Final Safety Analysis Report (FSAR), Volume 2, Accident Model Document (AMD) describes potential accident scenarios during the Galileo mission and evaluates the response of the LWRHUs to the associated accident environments. Any resulting source terms, consisting of PuO2 (with Pu-238 the dominant radionuclide), are then described in terms of curies released, particle size distribution, release location, and probabilities. This volume (LWRHU-FSAR, Volume 3, Nuclear Risk Analysis Document (NRAD)) contains the radiological analyses which estimate the consequences of the accident scenarios described in the AMD. It also contains the quantification of mission risks resulting from the LWRHUs based on consideration of all accident scenarios and their probabilities. Estimates of source terms and their characteristics derived in the AMD are used as inputs to the analyses in the NRAD. The Failure Abort Sequence Trees (FASTs) presented in the AMD define events for which source terms occur and quantify them. Based on this information, three types of source term cases (most probable, maximum, and expectation) for each mission phase were developed for use in evaluating the radiological consequences and mission risks. 4 refs., 5 figs., 8 tabs.

  2. Reentry response of the light weight radioisotope heater unit resulting from a Venus-Earth-Earth Gravity Assist maneuver accident

    SciTech Connect

    Hagan, J.C.

    1988-10-01

    Reentry analyses consisting of ablation response, thermal response and thermal stress response have been conducted on the Light Weight Radioisotope Heater Unit for Galileo/VEEGA reentry conditions. Sequential ablation analyses of the LWRHU aeroshell, the fuel clad, and the fuel pellet have been conducted in reentry regimes where the aeroshell has been deemed to fail. The failure criterion for ablation is assumed to be recession corresponding to 50% of the wall thickness (the design criterion recommended in the DOE Overall Safety Manual). Although the analyses have been carried far beyond this limit (as presented and discussed herein), JHU/APL endorses the position that failure may occur at the time that this recession is achieved or at lower altitudes within the heat pulse considering the uncertainties in the aerodynamic, thermodynamic, and thermo-structural analyses and modeling. These uncertainties result mainly because of the high energies involved in the VEEGA reentries compared to orbital decay reentries. Risk evaluations should consider the fact that for shallow flight paths the unit may disassemble at high-altitude as a result of ablation or may remain intact until it impacts with a clad that had been molten. 80 refs., 46 figs., 16 tabs.

  3. Application of light-weight filtration media in an anoxic biofilter for nitrate removal from micro-polluted surface water.

    PubMed

    Wang, Zheng; Fei, Xiang; He, Shengbing; Huang, Jungchen; Zhou, Weili

    The research investigated nitrate removal from micro-polluted surface water by the single-stage process of anoxic biofilter using light-weight polystyrene beads as filtration media. In this study, sodium acetate was used as an external carbon source and the nitrate removal efficiency under different regimes of hydraulic loading rate (HLR), water temperature, and C/N ratio was studied. In addition, the effect of backwash on denitrification efficiency was investigated. The results show that the biofilter achieved a high nitrate removal efficiency in 2 weeks at water temperatures ranging between 22 and 25 °C at a C/N ratio (COD:NO3(-)-N) of 6:1. Besides, the average removal efficiency of nitrate at HLRs of 5.66, 7.07 and 8.49 m(3) m(-2) h(-1) were 87.5, 87.3 and 87.1%, respectively. The average removal efficiency of nitrate nitrogen was 13.9% at a HLR of 5.66 m(3) m(-2) h(-1) at water temperatures of 12-14 °C, then it increased to 93.7% when the C/N ratio increased to 10. It suggests that the optimal hydraulic retention time is at water temperatures of 8-10 °C. The water consumption rate of backwash was about 0.2-0.3%, and denitrification efficiency returned to the normal level in 12 h after backwash.

  4. Light-weight sandwich panel honeycomb core with hybrid carbon-glass fiber composite skin for electric vehicle application

    NASA Astrophysics Data System (ADS)

    Cahyono, Sukmaji Indro; Widodo, Angit; Anwar, Miftahul; Diharjo, Kuncoro; Triyono, Teguh; Hapid, A.; Kaleg, S.

    2016-03-01

    The carbon fiber reinforced plastic (CFRP) composite is relative high cost material in current manufacturing process of electric vehicle body structure. Sandwich panels consisting polypropylene (PP) honeycomb core with hybrid carbon-glass fiber composite skin were investigated. The aim of present paper was evaluate the flexural properties and bending rigidity of various volume fraction carbon-glass fiber composite skins with the honeycomb core. The flexural properties and cost of panels were compared to the reported values of solid hybrid Carbon/Glass FRP used for the frame body structure of electric vehicle. The finite element model of represented sandwich panel was established to characterize the flexural properties of material using homogenization technique. Finally, simplified model was employed to crashworthiness analysis for engine hood of the body electric vehicle structure. The good cost-electiveness of honeycomb core with hybrid carbon-glass fiber skin has the potential to be used as a light-weight alternative material in body electric vehicle fabricated.

  5. Cryogenic explosion environment modeling and testing of space shuttle and light-weight radioisotope heater unit interactions

    SciTech Connect

    Johnson, E.W.

    1985-10-01

    In order to assess the risk to the world's populace in the event of a Space Shuttle accident when radioisotope-containing heat sources are on board, testing of that system must be performed to determine release point, environments required, and the size distribution of the released fuel. To evaluate the performance of the Light-Weight Radioisotope Heater Unit (LWRHU) (101 of these 1-W items are placed on the Galileo spacecraft which will be launched from the Space Shuttle), some high-velocity impact and flyer plate testing was carried out. The results showed that a bare urania-fueled LWRHU clad (approximately 1-mm thick platinum-30 wt % rhodium alloy) will withstand 1100 m/s flyer plate (3.5-mm thick aluminum) impacts and 330 m/s impacts upon the Space Shuttle floor (approximately 12-mm thick aluminum) without rupture or fuel release. Velocities in the order of 600 m/s on a steel surface will cause clad failure with fuel release. The fuel breakup patterns were characterized as to quantity in a specific size range. These data were employed in the formal Safety Analysis Report for the LWRHU to support the planned 1986 Galileo launch. 19 figs.

  6. Roulettes: a weak lensing formalism for strong lensing: I. Overview

    NASA Astrophysics Data System (ADS)

    Clarkson, Chris

    2016-08-01

    We present a new perspective on gravitational lensing. We describe a new extension of the weak lensing formalism capable of describing strongly lensed images. By integrating the nonlinear geodesic deviation equation, the amplification matrix of weak lensing is generalised to a sum over independent amplification tensors of increasing rank. We show how an image distorted by a generic lens may be constructed as a sum over ‘roulettes’, which are the natural curves associated with the independent spin modes of the amplification tensors. Highly distorted images can be constructed even for large sources observed near or within the Einstein radius of a lens where the shear and convergence are large. The amplitude of each roulette is formed from a sum over appropriate derivatives of the lensing potential. Consequently, measuring these individual roulettes for images around a lens gives a new way to reconstruct a strong lens mass distribution without requiring a lens model. This formalism generalises the convergence, shear and flexion of weak lensing to arbitrary order, and provides a unified bridge between the strong and weak lensing regimes. This overview paper is accompanied by a much more detailed paper II, arXiv:1603.04652.

  7. Subaru Weak Lensing Measurements of Four Strong Lensing Clusters: Are Lensing Clusters Over-Concentrated?

    SciTech Connect

    Oguri, Masamune; Hennawi, Joseph F.; Gladders, Michael D.; Dahle, Haakon; Natarajan, Priyamvada; Dalal, Neal; Koester, Benjamin P.; Sharon, Keren; Bayliss, Matthew

    2009-01-29

    We derive radial mass profiles of four strong lensing selected clusters which show prominent giant arcs (Abell 1703, SDSS J1446+3032, SDSS J1531+3414, and SDSS J2111-0115), by combining detailed strong lens modeling with weak lensing shear measured from deep Subaru Suprime-cam images. Weak lensing signals are detected at high significance for all four clusters, whose redshifts range from z = 0.28 to 0.64. We demonstrate that adding strong lensing information with known arc redshifts significantly improves constraints on the mass density profile, compared to those obtained from weak lensing alone. While the mass profiles are well fitted by the universal form predicted in N-body simulations of the {Lambda}-dominated cold dark matter model, all four clusters appear to be slightly more centrally concentrated (the concentration parameters c{sub vir} {approx} 8) than theoretical predictions, even after accounting for the bias toward higher concentrations inherent in lensing selected samples. Our results are consistent with previous studies which similarly detected a concentration excess, and increases the total number of clusters studied with the combined strong and weak lensing technique to ten. Combining our sample with previous work, we find that clusters with larger Einstein radii are more anomalously concentrated. We also present a detailed model of the lensing cluster Abell 1703 with constraints from multiple image families, and find the dark matter inner density profile to be cuspy with the slope consistent with -1, in agreement with expectations.

  8. LENSED: a code for the forward reconstruction of lenses and sources from strong lensing observations

    NASA Astrophysics Data System (ADS)

    Tessore, Nicolas; Bellagamba, Fabio; Metcalf, R. Benton

    2016-12-01

    Robust modelling of strong lensing systems is fundamental to exploit the information they contain about the distribution of matter in galaxies and clusters. In this work, we present LENSED, a new code which performs forward parametric modelling of strong lenses. LENSED takes advantage of a massively parallel ray-tracing kernel to perform the necessary calculations on a modern graphics processing unit (GPU). This makes the precise rendering of the background lensed sources much faster, and allows the simultaneous optimization of tens of parameters for the selected model. With a single run, the code is able to obtain the full posterior probability distribution for the lens light, the mass distribution and the background source at the same time. LENSED is first tested on mock images which reproduce realistic space-based observations of lensing systems. In this way, we show that it is able to recover unbiased estimates of the lens parameters, even when the sources do not follow exactly the assumed model. Then, we apply it to a subsample of the Sloan Lens ACS Survey lenses, in order to demonstrate its use on real data. The results generally agree with the literature, and highlight the flexibility and robustness of the algorithm.

  9. Harmonic imaging with fresnel beamforming in the presence of phase aberration.

    PubMed

    Nguyen, Man Minh; Shin, Junseob; Yen, Jesse

    2014-10-01

    Fresnel beamforming is a beamforming method with a delay profile similar in shape to a physical Fresnel lens. The advantage of Fresnel beamforming is the reduced channel count, which consists of four to eight transmit and two analog-to-digital receive channels. Fresnel beamforming was found to perform comparably to conventional delay-and-sum beamforming. However, the performance of Fresnel beamforming is highly dependent on focal errors. These focal errors result in high side-lobe levels and further reduce the performance of Fresnel beamforming in the presence of phase aberration. With the advantages of lower side-lobe levels and suppression of aberration effects, harmonic imaging offers an effective solution to the limitations of Fresnel beamforming. We describe the implementation of tissue harmonic imaging and pulse inversion harmonic imaging in Fresnel beamforming, followed by dual apodization with cross-correlation, to improve image quality. Compared with conventional delay-and-sum beamforming, experimental results indicated contrast-to-noise ratio improvements of 10%, 49% and 264% for Fresnel beamforming using tissue harmonic imaging in the cases of no aberrator, 5-mm pork aberrator and 12-mm pork aberrator, respectively. These improvements were 22%, 57% and 352% for Fresnel beamforming using pulse inversion harmonic imaging. Moreover, dual apodization with cross-correlation was found to further improve the contrast-to-noise ratios in all cases. Harmonic imaging was also found to narrow the lateral beamwidth and shorten the axial pulse length by at least 25% and 21%, respectively, for Fresnel beamforming at different aberration levels. These results suggest the effectiveness of harmonic imaging in improving image quality for Fresnel beamforming, especially in the presence of phase aberration. Even though this combination of Fresnel beamforming and harmonic imaging does not outperform delay-and-sum beamforming combined with harmonic imaging, it provides the

  10. The evolution of lenses.

    PubMed

    Land, Michael F

    2012-11-01

    Structures which bend light and so form images are present in all the major phyla. Lenses with a graded refractive index, and hence reduced spherical aberration, evolved in the vertebrates, arthropods, annelid worms, and several times in the molluscs. Even cubozoan jellyfish have lens eyes. In some vertebrate eyes, multiple focal lengths allow some correction for chromatic aberration. In land vertebrates the cornea took over the main ray-bending task, leaving accommodation as the main function of the lens. The spiders are the only other group to make use of a single cornea as the optical system in their main eyes, and some of these - the salticids - have evolved a remarkable system based on image scanning. Similar scanning arrangements are found in some crustaceans, sea-snails and insect larvae.

  11. Lenses for JWST

    NASA Astrophysics Data System (ADS)

    Ebeling, Harald; Richard, Johan; Kneib, Jean-Paul; Repp, Andrew; Atek, Hakim; Egami, Eiichi; Windhorst, Rogier; Edge, Alastair

    2016-08-01

    JWST will dramatically advance our knowledge and understanding of the first generations of galaxies at z>10, their role in the re-ionization of the Universe, and the evolutionary processes that gave rise to the complexity and diversity of galaxies at the current epoch. As demonstrated by HST legacy projects like CLASH and the Hubble Frontier Fields, gravitational amplification by massive galaxy clusters can significantly extend the depth of the required observations. However, for JWST, reducing any diffuse background light will be just as crucial. We here propose Spitzer/IRAC observations of six massive cluster lenses, specifically selected as candidates for observation with JWST. By (a) quantifying the amount of intra-cluster light and (b) enabling us to improve our current lens models, the data resulting from the requested observations will be instrumental for the final selection of cluster targets that maximize the scientific returns of deep JWST observations.

  12. Pulsar lensing geometry

    NASA Astrophysics Data System (ADS)

    Liu, Siqi; Pen, Ue-Li; Macquart, J.-P.; Brisken, Walter; Deller, Adam

    2016-05-01

    We test the inclined sheet pulsar scintillation model (Pen & Levin) against archival very long baseline interferometry (VLBI) data on PSR 0834+06 and show that its scintillation properties can be precisely reproduced by a model in which refraction occurs on two distinct lens planes. These data strongly favour a model in which grazing-incidence refraction instead of diffraction off turbulent structures is the primary source of pulsar scattering. This model can reproduce the parameters of the observed diffractive scintillation with an accuracy at the percent level. Comparison with new VLBI proper motion results in a direct measure of the ionized interstellar medium (ISM) screen transverse velocity. The results are consistent with ISM velocities local to the PSR 0834+06 sight-line (through the Galaxy). The simple 1-D structure of the lenses opens up the possibility of using interstellar lenses as precision probes for pulsar lens mapping, precision transverse motions in the ISM, and new opportunities for removing scattering to improve pulsar timing. We describe the parameters and observables of this double screen system. While relative screen distances can in principle be accurately determined, a global conformal distance degeneracy exists that allows a rescaling of the absolute distance scale. For PSR B0834+06, we present VLBI astrometry results that provide (for the first time) a direct measurement of the distance of the pulsar. For most of the recycled millisecond pulsars that are the targets of precision timing observations, the targets where independent distance measurements are not available. The degeneracy presented in the lens modelling could be broken if the pulsar resides in a binary system.

  13. Cross-correlating Planck CMB lensing with SDSS: lensing-lensing and galaxy-lensing cross-correlations

    NASA Astrophysics Data System (ADS)

    Singh, Sukhdeep; Mandelbaum, Rachel; Brownstein, Joel R.

    2017-01-01

    We present results from cross-correlating Planck cosmic microwave background (CMB) lensing maps with the Sloan Digital Sky Survey (SDSS) galaxy lensing shape catalogue and BOSS (Baryon Oscillation Spectroscopic Survey) galaxy catalogues. For galaxy position versus CMB lensing cross-correlations, we measure the convergence signal around the galaxies in configuration space, using the BOSS LOWZ (z ˜ 0.30) and CMASS (z ˜ 0.57) samples. With fixed Planck 2015 cosmology, doing a joint fit with the galaxy clustering measurement, for the LOWZ (CMASS) sample we find a galaxy bias bg = 1.75 ± 0.04 (1.95 ± 0.02) and galaxy-matter cross-correlation coefficient rcc = 1.0 ± 0.2 (0.8 ± 0.1) using 20 < rp < 70 h-1 Mpc, consistent with results from galaxy-galaxy lensing. Using the same scales and including the galaxy-galaxy lensing measurements, we constrain Ωm = 0.284 ± 0.024 and relative calibration bias between the CMB lensing and galaxy lensing to be b_γ =0.82^{+0.15}_{-0.14}. The combination of galaxy lensing and CMB lensing also allows us to measure the cosmological distance ratios (with zl ˜ 0.3, zs ˜ 0.5) R=D_s D_{l,*}/D_{* D_{l,s}}=2.68± 0.29, consistent with predictions from the Planck 2015 cosmology (R=2.35). We detect the galaxy position-CMB convergence cross-correlation at small scales, rp < 1 h-1 Mpc, and find consistency with lensing by NFW haloes of mass Mh ˜ 1013 h-1 M⊙. Finally, we measure the CMB lensing-galaxy shear cross-correlation, finding an amplitude of A = 0.76 ± 0.23 (zeff = 0.35, θ < 2°) with respect to Planck 2015 Λ cold dark matter predictions (1σ level consistency). We do not find evidence for relative systematics between the CMB and SDSS galaxy lensing.

  14. Light-Weight Multispectral Uav Sensors and Their Capabilities for Predicting Grain Yield and Detecting Plant Diseases

    NASA Astrophysics Data System (ADS)

    Nebiker, S.; Lack, N.; Abächerli, M.; Läderach, S.

    2016-06-01

    In this paper we investigate the performance of new light-weight multispectral sensors for micro UAV and their application to selected tasks in agronomical research and agricultural practice. The investigations are based on a series of flight campaigns in 2014 and 2015 covering a number of agronomical test sites with experiments on rape, barley, onion, potato and other crops. In our sensor comparison we included a high-end multispectral multiSPEC 4C camera with bandpass colour filters and reference channel in zenith direction and a low-cost, consumer-grade Canon S110 NIR camera with Bayer pattern colour filters. Ground-based reference measurements were obtained using a terrestrial hyperspectral field spectrometer. The investigations show that measurements with the high-end system consistently match very well with ground-based field spectrometer measurements with a mean deviation of just 0.01-0.04 NDVI values. The low-cost system, while delivering better spatial resolutions, expressed significant biases. The sensors were subsequently used to address selected agronomical questions. These included crop yield estimation in rape and barley and plant disease detection in potato and onion cultivations. High levels of correlation between different vegetation indices and reference yield measurements were obtained for rape and barley. In case of barley, the NDRE index shows an average correlation of 87% with reference yield, when species are taken into account. With high geometric resolutions and respective GSDs of down to 2.5 cm the effects of a thrips infestation in onion could be analysed and potato blight was successfully detected at an early stage of infestation.

  15. ULE design considerations for a 3m class light weighted mirror blank for E-ELT M5

    NASA Astrophysics Data System (ADS)

    Fox, Andrew; Hobbs, Tom; Edwards, Mary; Arnold, Matthew; Sawyer, Kent

    2016-07-01

    It is expected that the next generation of large ground based astronomical telescopes will need large fast-steering/tip-tilt mirrors made of ultra-lightweight construction. These fast-steering mirrors are used to continuously correct for atmospheric disturbances and telescope vibrations. An example of this is the European Extremely Large Telescope (E-ELT) M5 lightweight mirror, which is part of the Tip-Tilt/Field-Stabilization Unit. The baseline design for the E-ELT M5 mirror, as presented in the E-ELT Construction Proposal, is a closed-back ULE mirror with a lightweight core using square core cells. Corning Incorporated (Corning) has a long history of manufacturing lightweight mirror blanks using ULE in a closed-back construction, going back to the 1960's, and includes the Hubble Space Telescope primary mirror, Subaru Telescope secondary and tertiary mirrors, the Magellan I and II tertiary mirrors, and Kepler Space Telescope primary mirror, among many others. A parametric study of 1-meter class lightweight mirror designs showed that Corning's capability to seal a continuous back sheet to a light-weighted core structure provides superior mirror rigidity, in a near-zero thermal expansion material, relative to other existing technologies in this design space. Corning has investigated the parametric performance of several design characteristics for a 3-meter class lightweight mirror blank for the E-ELT M5. Finite Element Analysis was performed on several design scenarios to obtain weight, areal density, and first Eigen frequency. This paper presents an overview of Corning ULE and lightweight mirror manufacturing capabilities, the parametric performance of design characteristics for 1-meter class and 3-meter class lightweight mirrors, as well as the manufacturing advantages and disadvantages of those characteristics.

  16. Static corrections in mountainous areas using Fresnel-wavepath tomography

    NASA Astrophysics Data System (ADS)

    Zhang, Jianzhong; Shi, Tai-kun; Zhao, Yasheng; Zhou, Hua-wei

    2014-12-01

    We propose a 3-D Fresnel-wavepath tomography based on simultaneous iterative reconstruction technique (SIRT) with adaptive relaxation factors, in order to obtain effective near-surface velocity models for static corrections. We derived a formula to calculate the optimal relaxation factor for tomographic inversion to increase the convergence rate and thus the efficiency of the Fresnel-wavepath tomography. A forward method based on bilinear traveltime interpolation and the wavefront group marching is applied to achieve fast and accurate computation of the wavefront traveltimes in 3-D heterogeneous models. The new method is able to achieve near-surface velocity models effective in estimating long-period static corrections, and the remaining traveltime residuals after the tomographic inversion are used to estimate the short-period static corrections via a surface-consistent decomposition. The new method is tested using 3-D synthetic data and 3-D field dataset acquired in a complex mountainous area in southwestern China.

  17. Compressive optical image watermarking using joint Fresnel transform correlator architecture

    NASA Astrophysics Data System (ADS)

    Li, Jun; Zhong, Ting; Dai, Xiaofang; Yang, Chanxia; Li, Rong; Tang, Zhilie

    2017-02-01

    A new optical image watermarking technique based on compressive sensing using joint Fresnel transform correlator architecture has been presented. A secret scene or image is first embedded into a host image to perform optical image watermarking by use of joint Fresnel transform correlator architecture. Then, the watermarked image is compressed to much smaller signal data using single-pixel compressive holographic imaging in optical domain. At the received terminal, the watermarked image is reconstructed well via compressive sensing theory and a specified holographic reconstruction algorithm. The preliminary numerical simulations show that it is effective and suitable for optical image security transmission in the coming absolutely optical network for the reason of the completely optical implementation and largely decreased holograms data volume.

  18. Transmittance-optimized, point-focus Fresnel lens solar concentrator

    SciTech Connect

    Oneill, M.J.; Goldberg, V.R.; Muzzy, D.B.

    1982-07-01

    The development of a point-focus Fresnel lens solar concentrator for high-temperature solar thermal energy system applications is discussed. The concentrator utilizes a transmittance-optimized, short-focal-length, dome-shaped refractive Fresnel lens as the optical element. This concentrator combines both good optical performance and a large tolerance for manufacturing, deflection, and tracking errors. The conceptual design of an 11-meter diameter concentrator which should provide an overall collector efficiency of about 70% at an 815 C (1500 F) receiver operating temperature and a 1500X geometric concentration ratio (lens aperture area/receiver aperture area) was completed. Results of optical and thermal analyses of the collector, a discussion of manufacturing methods for making the large lens, and an update on the current status and future plans of the development program are included.

  19. Transmittance-optimized, point-focus Fresnel lens solar concentrator

    SciTech Connect

    Oneill, M.J.

    1984-03-01

    The development of a point-focus Fresnel lens solar concentrator for high-temperature solar thermal energy system applications is discussed. The concentrator utilizes a transmittance-optimized, short-focal-length, dome-shaped refractive Fresnel lens as the optical element. This concentrator combines both good optical performance and a large tolerance for manufacturing, deflection, and tracking errors. The conceptual design of an 11-meter diameter concentrator which should provide an overall collector efficiency of about 70% at an 815 C (1500 F) receiver operating temperature and a 1500X geometric concentration ratio (lens aperture area/receiver aperture area) was completed. Results of optical and thermal analyses of the collector, a discussion of manufacturing methods for making the large lens, and an update on the current status and future plans of the development program are included.

  20. Low chromatic Fresnel lens for broadband attosecond XUV pulse applications.

    PubMed

    Pan, Huaihai; Späth, Christian; Guggenmos, Alexander; Chew, Soo Hoon; Schmidt, Jürgen; Zhao, Quan-Zhong; Kleineberg, Ulf

    2016-07-25

    Fresnel zone plates show a great potential in achieving high spatial resolution imaging or focusing for XUV and soft/hard X-ray radiation, however they are usually strictly monochromatic due to strong chromatic dispersion and thus do not support broad radiation spectra, preventing their application to attosecond XUV pulses. Here we report on the design and theoretical simulations based on the design of an achromatic hybrid optics combining both, a refractive and diffractive lens in one optical element. We are able to show by calculation that the chromatic dispersion along the optical axis can be greatly reduced compared to a standard Fresnel zone plate while preserving the temporal structure of the attosecond XUV pulses at focus.

  1. Diffraction theory for azimuthally structured Fresnel zone plate.

    PubMed

    Vierke, Thordis; Jahns, Jürgen

    2014-02-01

    A conventional Fresnel zone plate (FZP) consists of concentric rings with an alternating binary transmission of zero and one. In an azimuthally structured Fresnel zone plate (aFZP), the light transmission of the transparent zones is modulated in the azimuthal direction, too. The resulting structure is of interest for extreme ultraviolet and x-ray imaging, in particular, because of its improved mechanical stability as compared to the simple ring structure of an FZP. Here, we present an analysis of the optical performance of the aFZP based on scalar diffraction theory and show numerical results for the light distribution in the focal plane. These will be complemented by calculations of the optical transfer function.

  2. Array illumination of a Fresnel-Dammann zone plate.

    PubMed

    Ma, Yayao; Ye, Chaochao; Ke, Jie; Zhang, Junyong; Zhu, Jianqiang; Ling, Zunqing

    2016-09-10

    The traditional Dammann grating is a phase-only modulation, and its theoretical foundation is based on far-field diffraction. Here we extend the traditional Fresnel zone plate (FZP) into a Fresnel-Dammann zone plate (FDZP), which is, in essence, considered as a FZP with Dammann modulation. Different from the Dammann grating, a single FDZP can generate array illumination from the near field to the far field by means of amplitude-only modulation in the absence of phase modulation. We then give some array illuminations operated in a water window to validate the feasibility and validity. This kind of wave-front modulation technology can be applied to array focusing and imaging from the x-ray to the EUV region.

  3. Galaxy cluster lensing masses in modified lensing potentials

    SciTech Connect

    Barreira, Alexandre; Li, Baojiu; Jennings, Elise; Merten, Julian; King, Lindsay; Baugh, Carlton M.; Pascoli, Silvia

    2015-10-28

    In this study, we determine the concentration–mass relation of 19 X-ray selected galaxy clusters from the Cluster Lensing and Supernova Survey with Hubble survey in theories of gravity that directly modify the lensing potential. We model the clusters as Navarro–Frenk–White haloes and fit their lensing signal, in the Cubic Galileon and Nonlocal gravity models, to the lensing convergence profiles of the clusters. We discuss a number of important issues that need to be taken into account, associated with the use of non-parametric and parametric lensing methods, as well as assumptions about the background cosmology. Our results show that the concentration and mass estimates in the modified gravity models are, within the error bars, the same as in Λ cold dark matter. This result demonstrates that, for the Nonlocal model, the modifications to gravity are too weak at the cluster redshifts, and for the Galileon model, the screening mechanism is very efficient inside the cluster radius. However, at distances ~ [2–20] Mpc/h from the cluster centre, we find that the surrounding force profiles are enhanced by ~ 20–40% in the Cubic Galileon model. This has an impact on dynamical mass estimates, which means that tests of gravity based on comparisons between lensing and dynamical masses can also be applied to the Cubic Galileon model.

  4. Galaxy cluster lensing masses in modified lensing potentials

    DOE PAGES

    Barreira, Alexandre; Li, Baojiu; Jennings, Elise; ...

    2015-10-28

    In this study, we determine the concentration–mass relation of 19 X-ray selected galaxy clusters from the Cluster Lensing and Supernova Survey with Hubble survey in theories of gravity that directly modify the lensing potential. We model the clusters as Navarro–Frenk–White haloes and fit their lensing signal, in the Cubic Galileon and Nonlocal gravity models, to the lensing convergence profiles of the clusters. We discuss a number of important issues that need to be taken into account, associated with the use of non-parametric and parametric lensing methods, as well as assumptions about the background cosmology. Our results show that the concentrationmore » and mass estimates in the modified gravity models are, within the error bars, the same as in Λ cold dark matter. This result demonstrates that, for the Nonlocal model, the modifications to gravity are too weak at the cluster redshifts, and for the Galileon model, the screening mechanism is very efficient inside the cluster radius. However, at distances ~ [2–20] Mpc/h from the cluster centre, we find that the surrounding force profiles are enhanced by ~ 20–40% in the Cubic Galileon model. This has an impact on dynamical mass estimates, which means that tests of gravity based on comparisons between lensing and dynamical masses can also be applied to the Cubic Galileon model.« less

  5. Galaxy cluster lensing masses in modified lensing potentials

    NASA Astrophysics Data System (ADS)

    Barreira, Alexandre; Li, Baojiu; Jennings, Elise; Merten, Julian; King, Lindsay; Baugh, Carlton M.; Pascoli, Silvia

    2015-12-01

    We determine the concentration-mass relation of 19 X-ray selected galaxy clusters from the Cluster Lensing and Supernova Survey with Hubble survey in theories of gravity that directly modify the lensing potential. We model the clusters as Navarro-Frenk-White haloes and fit their lensing signal, in the Cubic Galileon and Nonlocal gravity models, to the lensing convergence profiles of the clusters. We discuss a number of important issues that need to be taken into account, associated with the use of non-parametric and parametric lensing methods, as well as assumptions about the background cosmology. Our results show that the concentration and mass estimates in the modified gravity models are, within the error bars, the same as in Λ cold dark matter. This result demonstrates that, for the Nonlocal model, the modifications to gravity are too weak at the cluster redshifts, and for the Galileon model, the screening mechanism is very efficient inside the cluster radius. However, at distances ˜(2-20) Mpc h-1 from the cluster centre, we find that the surrounding force profiles are enhanced by ˜20-40 per cent in the Cubic Galileon model. This has an impact on dynamical mass estimates, which means that tests of gravity based on comparisons between lensing and dynamical masses can also be applied to the Cubic Galileon model.

  6. Polarization controllable Fresnel lens using dye-doped liquid crystals.

    PubMed

    Lin, Tsung-Hsien; Huang, Yuhua; Fuh, Andy Y G; Wu, Shin-Tson

    2006-03-20

    A scattering-free, polarization controllable Fresnel zone plate lens is demonstrated using a photo-induced alignment of the dye-doped liquid crystal film. This photo-aligned liquid crystal zone plate provides orthogonal polarization states for odd and even zones. The different focus orders can be separated because of their different polarization states. The fabrication process is relatively simple and the operation voltage is less than 5 V(rms).

  7. Ultrasonic imaging using trapped energy mode Fresnel lens transducers

    NASA Technical Reports Server (NTRS)

    Das, P.; Talley, S.; Kraft, R.; Tiersten, H. F.; Mcdonald, J. F.

    1980-01-01

    Trapped-energy focusing transducers operating in the 2-5 MHz range have been fabricated by plating concentric rings of electrodes on a piezoelectric plate. The concentric ring structure acts as a Fresnel lens and can be used to obtain excellent lateral focusing of ultrasonic waves. The trapping is sufficiently strong to permit optimization of electrode spacings to suppress spurious virtual foci and ring sidelobes.

  8. Low-frequency Fresnel mirrors for fluorescence detectors

    NASA Astrophysics Data System (ADS)

    Diaz-Anzures, J.; Cordero-Davila, A.; Gonzalez-Garcia, J.; Martinez-Bravo, O.; Robledo-Sanchez, C.; Khrenov, B. A.; Garipov, G. K.

    2004-07-01

    In this work we present several designs of a Fresnel mirror with small number of rings (low frequency) to be used in fluorescence detectors aimed for study of ultra high energy cosmic rays. Being segmented the Fresnel mirror has an advantage of simple development from a compact package to a "plane" large area mirror-concentrator. This advantage is important for detectors in space and detectors at remote mountain sites. In this work, we investigated four possible ways of generating a focusing surface. In the first (main) design, the mirror consists of sections belonging to several parabolic surfaces. In this case the best focusing of a source on optical axis is achieved--the Fresnel mirror operates as parabolic mirror. This design is the best for a space "telescope", observing a source from large distances. Close to this design are mirror options with sections of a common parabolic surface and with sections of several spherical surfaces. The simplest for construction is the mirror with sections of a common spherical surface. In this design, focusing of a source on optical axis is much poorer than in previous options, but the mirror may be used in the experiments needed a wide field of view (FOV) with rough angular resolution. An advantage of this design is simplicity of the mirror construction which is shown in the mirror prototype construction and its testing. Results of the focal spot measurements are presented. This simple design of the Fresnel mirror is planned for use in the Pico de Orizaba mountain hybrid array where the wide field of view is important.

  9. Application of white light Fresnel diffractometry to film thickness measurement.

    PubMed

    Hassani, Khosrow; Ashrafganjoie, Mehdi; Tavassoly, Mohammad Taghi

    2016-03-01

    In this work we present the theoretical background and experimental procedure to measure the thickness of thin films by analyzing Fresnel diffraction patterns obtained from polychromatic illumination of phase-step samples. As examples of this technique, we measured the thicknesses of thin aluminum layers on glass substrates using three different broad-spectrum light sources. The results are in excellent agreement with independent interferometric measurements within less than 5% relative uncertainties.

  10. Fresnel diffractive imaging: Experimental study of coherence and curvature

    SciTech Connect

    Whitehead, L. W.; Williams, G. J.; Quiney, H. M.; Nugent, K. A.; Peele, A. G.; Paterson, D.; Jonge, M. D. de; McNulty, I.

    2008-03-01

    A Fresnel coherent diffractive imaging experiment is performed using a pinhole as a test object. The experimental parameters of the beam curvature and coherence length of the illuminating radiation are varied to investigate their effects on the reconstruction process. It is found that a sufficient amount of curvature across the sample strongly ameliorates the effects of low coherence, even when the sample size exceeds the coherence length.

  11. Nanoscale Fresnel coherent diffraction imaging tomography using ptychography.

    PubMed

    Peterson, I; Abbey, B; Putkunz, C T; Vine, D J; van Riessen, G A; Cadenazzi, G A; Balaur, E; Ryan, R; Quiney, H M; McNulty, I; Peele, A G; Nugent, K A

    2012-10-22

    We demonstrate Fresnel Coherent Diffractive Imaging (FCDI) tomography in the X-ray regime. The method uses an incident X-ray illumination with known curvature in combination with ptychography to overcome existing problems in diffraction imaging. The resulting tomographic reconstruction represents a 3D map of the specimen's complex refractive index at nano-scale resolution. We use this technique to image a lithographically fabricated glass capillary, in which features down to 70nm are clearly resolved.

  12. Control Program and Optical Improvements of Fresnel Microspectrometer

    NASA Technical Reports Server (NTRS)

    Park, Yeonjoon; King, Glen; Choi, Sang; Elliott, James

    2011-01-01

    A microspectrometer has a circular geometry, and is designed with the Fresnel diffraction equation. This enables a dramatic miniaturization of the optical parts of a spectrometer over 100 times by volume. Therefore, it enables the construction of spectrometer arrays such as 100X100 microspectrometers for tunable multispectral or hyper-spectral imaging. It can be used for a massive, simultaneous spectral scan from multiple optical sources such as 10,000 optical fibers.

  13. Mini-dome Fresnel lens photovoltaic concentrator development

    NASA Technical Reports Server (NTRS)

    Oneill, Mark J.; Piszczor, Michael F., Jr.

    1991-01-01

    Since 1986 work on a new high-performance, light-weight space photovoltaic concentration array has been conducted. An update on the mini-dome lens concentrator array development program is provided. Recent prototype cell and lens test results indicate that near-term array performance goals of 300 w/sq m and 100 w/kg are feasible, and that a longer-term goal of 200 w/kg is reasonable.

  14. Sensitive voltage-dependent diffraction of a liquid crystal Fresnel lens.

    PubMed

    Hung, Wen-Chi; Chen, Yu-Jen; Lin, Chia-Huey; Jiang, I-Min; Hsu, Tzu-Fang

    2009-04-10

    This investigation proposes a Fresnel liquid crystal (LC) lens with high diffraction efficiency and a low driving voltage. A Fresnel zone electrode was fabricated on a glass plate. A Fresnel zone-distributed electric field in the LC cell was induced by a proper driving voltage, yielding a concentric structure of LCs as a Fresnel phase lens. A remarkable diffraction efficiency of ~39%, close to the theoretical limit of 40.5%, was detected when the LC lens was probed using a polarized incident beam with a wavelength of 632.8 nm. The diffraction efficiency of the Fresnel LC lens was demonstrated to depend sensitively on the applied voltage. The most suitable driving voltage of the Fresnel LC lens was as low as 0.9 V. This study may support progress in the electrical modulation of the optical properties of various optical systems.

  15. Specular highlights of plastic surfaces and the Fresnel coefficient

    NASA Astrophysics Data System (ADS)

    Angelopoulou, Elli; Poger, Sofya

    2004-10-01

    One of the biggest clues in specularity detection algorithms is the color of the specular highlights. There is a prevalent assumption that the color of specularities for materials like plastics and ceramics can be approximated by the color of the incident light. We show that such an assumption is not generally appropriate because of the effects of the Fresnel reflectance coefficient and its dependence on wavelength. Our theoretical analysis establishes that the sensitivity of the Fresnel term to the wavelength variations of the refractive index can be at least as large as 15%. Our experiments demonstrate that, even with traditional RGB color cameras, the recorded color of specular highlights is distinct from the color of the incident light. Furthermore, by computing the spectral gradients (i.e. the partial derivatives of the image with respect to wavelength) at specular regions we can isolate the Fresnel term up to an additive illumination constant. Our theory is supported by experiments performed on multispectral images of different colored plastic tiles. The refractive indices of the opaque plastics were measured using a specialized spectroscopic ellipsometer. The computed spectral gradients of the tile specularities exhibited a less than 2.5% deviation from the predicted theoretical values.

  16. Ophthalmic halo reduced lenses design

    NASA Astrophysics Data System (ADS)

    Limon, Ofer; Zalevsky, Zeev

    2015-05-01

    The halo effect is a very problematic visual artifact occurring in extended depth of focus or multi-focal ophthalmic lenses such as e.g. intra-ocular (after cataract surgery) or contact lenses when used in dark illumination conditions. This artifact is generated due to surface structures added on top of those lenses in order to increase their depth of focus or to realize multiple focal lengths. In this paper we present novel solution that can resolve this major problem of ophthalmic lenses. The proposed solution involves modification to the surface structure that realizes the extended depth of focus. Our solution is fabricated and numerically and experimentally validated also in preliminary in-vivo trials.

  17. KINOFORM LENSES - TOWARD NANOMETER RESOLUTION.

    SciTech Connect

    STEIN, A.; EVANS-LUTTERODT, K.; TAYLOR, A.

    2004-10-23

    While hard x-rays have wavelengths in the nanometer and sub-nanometer range, the ability to focus them is limited by the quality of sources and optics, and not by the wavelength. A few options, including reflective (mirrors), diffractive (zone plates) and refractive (CRL's) are available, each with their own limitations. Here we present our work with kinoform lenses which are refractive lenses with all material causing redundant 2{pi} phase shifts removed to reduce the absorption problems inherently limiting the resolution of refractive lenses. By stacking kinoform lenses together, the effective numerical aperture, and thus the focusing resolution, can be increased. The present status of kinoform lens fabrication and testing at Brookhaven is presented as well as future plans toward achieving nanometer resolution.

  18. CMB lensing and giant rings

    SciTech Connect

    Rathaus, Ben; Itzhaki, Nissan E-mail: ben.rathaus@gmail.com

    2012-05-01

    We study the CMB lensing signature of a pre-inationary particle (PIP), assuming it is responsible for the giant rings anomaly that was found recently in the WMAP data. Simulating Planck-like data we find that generically the CMB lensing signal to noise ratio associated with such a PIP is quite small and it would be difficult to cross correlate the temperature giant rings with the CMB lensing signal. However, if the pre-inationary particle is also responsible for the bulk flow measured from the local large scale structure, which happens to point roughly at the same direction as the giant rings, then the CMB lensing signal to noise ratio is fairly significant.

  19. HUBBLE'S TOP TEN GRAVITATIONAL LENSES

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The NASA Hubble Space Telescope serendipitous survey of the sky has uncovered exotic patterns, rings, arcs and crosses that are all optical mirages produced by a gravitational lens, nature's equivalent of having giant magnifying glass in space. Shown are the top 10 lens candidates uncovered in the deepest 100 Hubble fields. Hubble's sensitivity and high resolution allow it to see faint and distant lenses that cannot be detected with ground-based telescopes whose images are blurred by Earth's atmosphere. [Top Left] - HST 01248+0351 is a lensed pair on either side of the edge-on disk lensing galaxy. [Top Center] - HST 01247+0352 is another pair of bluer lensed source images around the red spherical elliptical lensing galaxy. Two much fainter images can be seen near the detection limit which might make this a quadruple system. [Top Right] - HST 15433+5352 is a very good lens candidate with a bluer lensed source in the form of an extended arc about the redder elliptical lensing galaxy. [Middle Far Left] - HST 16302+8230 could be an 'Einstein ring' and the most intriguing lens candidate. It has been nicknamed the 'the London Underground' since it resembles that logo. [Middle Near Left] - HST 14176+5226 is the first, and brightest lens system discovered in 1995 with the Hubble telescope. This lens candidate has now been confirmed spectroscopically using large ground-based telescopes. The elliptical lensing galaxy is located 7 billion light-years away, and the lensed quasar is about 11 billion light-years distant. [Middle Near Right] - HST 12531-2914 is the second quadruple lens candidate discovered with Hubble. It is similar to the first, but appears smaller and fainter. [Middle Far Right] - HST 14164+5215 is a pair of bluish lensed images symmetrically placed around a brighter, redder galaxy. [Bottom Left] - HST 16309+8230 is an edge-on disk-like galaxy (blue arc) which has been significantly distorted by the redder lensing elliptical galaxy. [Bottom Center] - HST 12368

  20. Astrophysical Applications of Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Mediavilla, Evencio; Muñoz, Jose A.; Garzón, Francisco; Mahoney, Terence J.

    2016-10-01

    Contributors; Participants; Preface; Acknowledgements; 1. Lensing basics Sherry H. Suyu; 2. Exoplanet microlensing Andrew Gould; 3. Case studies of microlensing Veronica Motta and Emilio Falco; 4. Microlensing of quasars and AGN Joachim Wambsganss; 5. DM in clusters and large-scale structure Peter Schneider; 6. The future of strong lensing Chris Fassnacht; 7. Methods for strong lens modelling Charles Keeton; 8. Tutorial on inverse ray shooting Jorge Jimenez-Vicente.

  1. The Thirring-Lense Effect

    NASA Astrophysics Data System (ADS)

    Embacher, Franz

    The Thirring-Lense effect is the phenomenon that an observer near a rotating mass, being in a state which is non-rotating with respect to the rest of the universe, experiences extra inertial forces, i.e. becomes dizzy. The first anticipation of the effect goes back to Ernst Mach; its first quantitative prediction on the basis of general relativity was given by Hans Thirring and Joseph Lense. Almost ninety years later, the effect seems to be experimentally verified.

  2. Electrically switchable liquid crystal Fresnel lens using UV-modified alignment film.

    PubMed

    Jeng, Shie-Chang; Hwang, Shug-June; Horng, Jing-Shyang; Lin, Kuo-Ren

    2010-12-06

    A simple method to make a switchable liquid crystal (LC) Fresnel lens with high diffraction efficiency and a low driving voltage was proposed based on the photo-induced surface modification of the vertical alignment layer. UV illumination alters the pretilt angle of alignment layers, a Fresnel zone-distribution hybrid alignment in the homeotropic LC cell can be straightforwardly achieved through UV exposure, yielding a concentric structure of the Fresnel phase LC lens. A remarkable diffraction efficiency of ~31.4%, close to the measured diffraction efficiency of the used Fresnel-zone-plate mask of 32%, was detected using a linearly polarized incident beam.

  3. Solar energy system with composite concentrating lenses

    SciTech Connect

    Genequand, P.; Stark, V.

    1980-12-09

    In order to improve the efficiency of a solar energy system utilizing a Fresnel lens for concentrating solar rays on a conduit system or the like, only the central portion of a Fresnel lens, otherwise of large width, is utilized and slide assemblies, each containing a plurality of slats with a reflective coating and disposed at an angle such as to reflect solar energy to the same focal point as the Fresnel lens, are disposed on each side of the lens thereby effectively increasing the aperture of the lens and increasing efficiency of concentration.

  4. Micro-optofluidic Lenses: A review

    PubMed Central

    Nguyen, Nam-Trung

    2010-01-01

    This review presents a systematic perspective on the development of micro-optofluidic lenses. The progress on the development of micro-optofluidic lenses are illustrated by example from recent literature. The advantage of micro-optofluidic lenses over solid lens systems is their tunability without the use of large actuators such as servo motors. Depending on the relative orientation of light path and the substrate surface, micro-optofluidic lenses can be categorized as in-plane or out-of-plane lenses. However, this review will focus on the tunability of the lenses and categorizes them according to the concept of tunability. Micro-optofluidic lenses can be either tuned by the liquid in use or by the shape of the lens. Micro-optofluidic lenses with tunable shape are categorized according to the actuation schemes. Typical parameters of micro-optofluidic lenses reported recently are compared and discussed. Finally, perspectives are given for future works in this field. PMID:20714369

  5. Triple-junction solar cell performance under Fresnel-based concentrators taking into account chromatic aberration and off-axis operation

    NASA Astrophysics Data System (ADS)

    Espinet-González, P.; Mohedano, R.; García, I.; Zamora, P.; Rey-Stolle, I.; Benitez, P.; Algora, C.; Cvetkovic, A.; Hernández, M.; Chaves, J.; Miñano, J. C.; Li, Y.

    2012-10-01

    Concentration photovoltaic (CPV) systems might produce quite uneven irradiance distributions (both on their level and on their spectral distribution) on the solar cell. This effect can be even more evident when the CPV system is slightly off-axis, since they are often designed to assure good uniformity only at normal incidence. The non-uniformities both in absolute irradiance and spectral content produced by the CPV systems, can originate electrical losses in multi-junction solar cells (MJSC). This works is focused on the integration of ray-tracing methods for simulating the irradiance and spectrum maps produced by different optic systems throughout the solar cell surface, with a 3D fully distributed circuit model which simulates the electrical behavior of a state-of-the-art triple-junction solar cell under the different light distributions obtained with ray-tracing. In this study four different CPV system (SILO, XTP, RTP, and FK) comprising Fresnel lenses concentrating sunlight onto the same solar cell are modeled when working on-axis and 0.6 degrees off-axis. In this study the impact of non-uniformities on a CPV system behavior is revealed. The FK outperforms other Fresnel-based CPV systems in both on-axis and off-axis conditions.

  6. Thermal lensing in ocular media

    NASA Astrophysics Data System (ADS)

    Vincelette, Rebecca Lee

    2009-12-01

    This research was a collaborative effort between the Air Force Research Laboratory (AFRL) and the University of Texas to examine the laser-tissue interaction of thermal lensing induced by continuous-wave, CW, near-infrared, NIR, laser radiation in the eye and its influence on the formation of a retinal lesion from said radiation. CW NIR laser radiation can lead to a thermal lesion induced on the retina given sufficient power and exposure duration as related to three basic parameters; the percent of transmitted energy to, the optical absorption of, and the size of the laser-beam created at the retina. Thermal lensing is a well-known phenomenon arising from the optical absorption, and subsequent temperature rise, along the path of the propagating beam through a medium. Thermal lensing causes the laser-beam profile delivered to the retina to be time dependent. Analysis of a dual-beam, multidimensional, high-frame rate, confocal imaging system in an artificial eye determined the rate of thermal lensing in aqueous media exposed to 1110, 1130, 1150 and 1318-nm wavelengths was related to the power density created along the optical axis and linear absorption coefficient of the medium. An adaptive optics imaging system was used to record the aberrations induced by the thermal lens at the retina in an artificial eye during steady-state. Though the laser-beam profiles changed over the exposure time, the CW NIR retinal damage thresholds between 1110--1319-nm were determined to follow conventional fitting algorithms which neglected thermal lensing. A first-order mathematical model of thermal lensing was developed by conjoining an ABCD beam propagation method, Beer's law of attenuation, and a solution to the heat-equation with respect to radial diffusion. The model predicted that thermal lensing would be strongest for small (< 4-mm) 1/e2 laser-beam diameters input at the corneal plane and weakly transmitted wavelengths where less than 5% of the energy is delivered to the retina

  7. Breeding gravitational lenses

    NASA Astrophysics Data System (ADS)

    Liesenborgs, J.; de Rijcke, S.; Dejonghe, H.; Bekaert, P.

    2011-03-01

    Gravitational lenses are a spectacular astrophysical phenomenon, a cosmic mirage caused by the gravitational deflection of light in which multiple images of a same background object can be seen. Their beauty is only exceeded by their usefulness, as the gravitational lens effect is a direct probe of the total mass of the deflecting object. Furthermore, since the image configuration arising from the gravitational lens effect depends on the exact gravitational potential of the deflector, it even holds the promise of learning about the distribution of the mass. In this presentation, a method for extracting the information encoded in the images and reconstructing the mass distribution is presented. Being a non-parametric method, it avoids making a priori assumptions about the shape of the mass distribution. At the core of the procedure lies a genetic algorithm, an optimization strategy inspired by Darwin's principle of ``survival of the fittest''. One only needs to specify a criterion to decide if one particular trial solution is deemed better than another, and the genetic algorithm will ``breed'' appropriate solutions to the problem. In a similar way, one can create a multi-objective genetic algorithm, capable of optimizing several fitness criteria at the same time. This provides a very flexible way to incorporate all the available information in the gravitational lens system: not only the positions and shapes of the multiple images are used, but also the so-called ``null space'', i.e. the area in which no such images can be seen. The effectiveness of this approach is illustrated using simulated data, which allows one to compare the reconstruction to the true mass distribution.

  8. Cosmology with weak lensing surveys.

    PubMed

    Munshi, Dipak; Valageas, Patrick

    2005-12-15

    Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening mass. Since the lensing effects arise from deflections of the light rays due to fluctuations of the gravitational potential, they can be directly related to the underlying density field of the large-scale structures. Weak gravitational surveys are complementary to both galaxy surveys and cosmic microwave background observations as they probe unbiased nonlinear matter power spectra at medium redshift. Ongoing CMBR experiments such as WMAP and a future Planck satellite mission will measure the standard cosmological parameters with unprecedented accuracy. The focus of attention will then shift to understanding the nature of dark matter and vacuum energy: several recent studies suggest that lensing is the best method for constraining the dark energy equation of state. During the next 5 year period, ongoing and future weak lensing surveys such as the Joint Dark Energy Mission (JDEM; e.g. SNAP) or the Large-aperture Synoptic Survey Telescope will play a major role in advancing our understanding of the universe in this direction. In this review article, we describe various aspects of probing the matter power spectrum and the bi-spectrum and other related statistics with weak lensing surveys. This can be used to probe the background dynamics of the universe as well as the nature of dark matter and dark energy.

  9. Surface gravity-wave lensing.

    PubMed

    Elandt, Ryan B; Shakeri, Mostafa; Alam, Mohammad-Reza

    2014-02-01

    Here we show that a nonlinear resonance between oceanic surface waves caused by small seabed features (the so-called Bragg resonance) can be utilized to create the equivalent of lenses and curved mirrors for surface gravity waves. Such gravity wave lenses, which are merely small changes to the seafloor topography and therefore are surface noninvasive, can focus or defocus the energy of incident waves toward or away from any desired focal point. We further show that for a broadband incident wave spectrum (i.e., a wave group composed of a multitude of different-frequency waves), a polychromatic topography (occupying no more than the area required for a monochromatic lens) can achieve a broadband lensing effect. Gravity wave lenses can be utilized to create localized high-energy wave zones (e.g., for wave energy harvesting or creating artificial surf zones) as well as to disperse waves in order to create protected areas (e.g., harbors or areas near important offshore facilities). In reverse, lensing of oceanic waves may be caused by natural seabed features and may explain the frequent appearance of very high amplitude waves in certain bodies of water.

  10. The M31 pixel lensing plan campaign: MACHO lensing and self-lensing signals

    SciTech Connect

    Calchi Novati, S.; Scarpetta, G.; Bozza, V.; Bruni, I.; Gualandi, R.; Dall'Ora, M.; De Paolis, F.; Ingrosso, G.; Nucita, A.; Strafella, F.; Dominik, M.; Jetzer, Ph.; Mancini, L.; Safonova, M.; Subramaniam, A.; Sereno, M.; Gould, A.; Collaboration: PLAN Collaboration

    2014-03-10

    We present the final analysis of the observational campaign carried out by the PLAN (Pixel Lensing Andromeda) collaboration to detect a dark matter signal in form of MACHOs through the microlensing effect. The campaign consists of about 1 month/year observations carried out over 4 years (2007-2010) at the 1.5 m Cassini telescope in Loiano (Astronomical Observatory of BOLOGNA, OAB) plus 10 days of data taken in 2010 at the 2 m Himalayan Chandra Telescope monitoring the central part of M31 (two fields of about 13' × 12.'6). We establish a fully automated pipeline for the search and the characterization of microlensing flux variations. As a result, we detect three microlensing candidates. We evaluate the expected signal through a full Monte Carlo simulation of the experiment completed by an analysis of the detection efficiency of our pipeline. We consider both 'self lensing' and 'MACHO lensing' lens populations, given by M31 stars and dark matter halo MACHOs, in M31 and the Milky Way, respectively. The total number of events is consistent with the expected self-lensing rate. Specifically, we evaluate an expected signal of about two self-lensing events. As for MACHO lensing, for full 0.5(10{sup –2}) M {sub ☉} MACHO halos, our prediction is for about four (seven) events. The comparatively small number of expected MACHO versus self-lensing events, together with the small number statistics at our disposal, do not enable us to put strong constraints on that population. Rather, the hypothesis, suggested by a previous analysis, on the MACHO nature of OAB-07-N2, one of the microlensing candidates, translates into a sizeable lower limit for the halo mass fraction in form of the would-be MACHO population, f, of about 15% for 0.5 M {sub ☉} MACHOs.

  11. Manufacturing injection-moleded Fresnel lens parquets for point-focus concentrating photovoltaic systems

    SciTech Connect

    Peters, E.M.; Masso, J.D.

    1995-10-01

    This project involved the manufacturing of curved-faceted, injection-molded, four-element Fresnel lens parquets for concentrating photovoltaic arrays. Previous efforts showed that high-efficiency (greater than 82%) Fresnel concentrators could be injection molded. This report encompasses the mold design, molding, and physical testing of a four-lens parquet for a solar photovoltaic concentrator system.

  12. Spatial-spectral (space-wavenumber) correspondence relationship and Fresnel zone spectra.

    PubMed

    Han, Pin; Hsieh, Tsung-Han; Liu, Yi-Ling

    2017-03-01

    A correspondence relationship between space and wavenumber for fully spatially coherent uniform monochromatic and polychromatic light in near- and far-field diffraction is fully illustrated, and it is used to study a phenomenon called the Fresnel zone spectra, which is verified experimentally. The spectra can be filtered or manipulated by moving the detection position relative to Fresnel zone plate along the optical axis.

  13. Calculation of Fresnel diffraction from 1D phase step by discrete Fourier transform

    NASA Astrophysics Data System (ADS)

    Aalipour, Rasoul

    2017-01-01

    When a part of an optical wave-front experiences a sharp change in its phase, Fresnel diffraction becomes appreciable. Sharp change in phase occurs as a wave-front strikes with a phase step. The intensity distributions of diffraction patterns of the phase step is formulated by applying Fresnel-Kirchhoff integral. For while the incident light on the step is coherent, the Fresnel-Kirchhoff integral can be solved by using familiar Fresnel integrals. But, when the incident light is partially coherent, one can not express the diffraction integral as the Fresnel integrals and the problem is summarized in solving some unusual integrals. In this report, we propose Fourier transform method for solving the Fresnel-Kirchhoff integral. In this regard we use discrete Fourier transform method and calculate Fresnel diffraction from the 1D phase step by FFT-based algorithms. This method does not have any restriction on the coherence and profile shape of the incident light. We show that the method have appropriate solutions for coherent and partially coherent lights. For the case of the coherent light illumination of the step, the obtained results are in good agreement with the calculated results by using the Fresnel integrals in reported literatures.

  14. Fabrication of grating-Fresnel lens by using PDMS based soft lithography

    NASA Astrophysics Data System (ADS)

    Ni, Kai; Hu, Haifei; Li, Xinghui; Zhou, Qian; Wang, Xiaohao; Zhang, Jinchao

    2016-10-01

    Fabrication of a new type hybrid plane optics, Grating-Fresnel (G-Fresnel) lens for miniature spectrometer is presented in this research. A polydimethylsiloxane (PDMS) based soft lithography technology is employed. In this method, the grating surface and Fresnel surface of the G-Fresnel lens are formed simultaneously by sandwiching the PDMS layer between a reverse Fresnel mold and a grating. Surface anti-adhesive treatment method has been proposed to solve the innate adhesion of PDMS layers. A fabrication system is constructed and a G-Fresnel with grating line spacing of 1.11μm (900 lines/mm) and Fresnel lens with a diameter of 25.4 mm and a focal length of 25 mm was successfully fabricated. Three-dimensional surface profilometry has been performed to examine the device quality. Measured results show that replicas remain high fidelity to its primary master mold. A miniature spectrometer system was constructed to evaluate the performances of this fabricated G-Fresnel lens. Experimental results show that the spectrometer can provide about 2 nm resolutions at wavelengths of 450nm, 532 nm, and 650 nm, which verified the effectiveness of this fabrication method.

  15. Full-field vibrometry with digital Fresnel holography

    SciTech Connect

    Leval, Julien; Picart, Pascal; Boileau, Jean Pierre; Pascal, Jean Claude

    2005-09-20

    A setup that permits full-field vibration amplitude and phase retrieval with digital Fresnel holography is presented. Full reconstruction of the vibration is achieved with a three-step stroboscopic holographic recording, and an extraction algorithm is proposed. The finite temporal width of the illuminating light is considered in an investigation of the distortion of the measured amplitude and phase. In particular, a theoretical analysis is proposed and compared with numerical simulations that show good agreement. Experimental results are presented for a loudspeaker under sinusoidal excitation; the mean quadratic velocity extracted from amplitude evaluation under two different measuring conditions is presented. Comparison with time averaging validates the full-field vibrometer.

  16. Domed Fresnel lens concentrator technology for space application

    NASA Technical Reports Server (NTRS)

    Piszczor, Michael F., Jr.; Oneill, Mark J.

    1989-01-01

    Over the past three years, NASA Lewis and Entech, Inc. have been investigating the use of high efficiency refractive photovoltaic concentrators for use in space. The design currently under investigation uses a square domed Fresnel lens to focus light on a GaAs concentrator cell. A prismatic cell cover, which directs light away from the front contacts and thus eliminates metalization losses, is applied to the top of the GaAs cell to further enhance array efficiency. The latest experimental results based on testing the GaAs cell/prism cover assembly at standard and operating conditions are presented.

  17. Fresnel reflection from a cavity with net roundtrip gain

    SciTech Connect

    Mansuripur, Tobias S.; Mansuripur, Masud

    2014-03-24

    A planewave incident on an active etalon with net roundtrip gain may be expected to diverge in field amplitude, yet applying the Fresnel formalism to Maxwell's equations admits a convergent solution. We describe this solution mathematically and provide additional insight by demonstrating the response of such a cavity to an incident beam of light. Cavities with net roundtrip gain have often been overlooked in the literature, and a clear understanding of their behavior yields insight to negative refraction in nonmagnetic media, a duality between loss and gain, amplified total internal reflection, and the negative-index lens.

  18. Fresnel diffraction and fractal patterns from polygonal apertures.

    PubMed

    Huang, J G; Christian, J M; McDonald, G S

    2006-11-01

    Two compact analytical descriptions of Fresnel diffraction patterns from polygonal apertures under uniform illumination are detailed. In particular, a simple expression for the diffracted field from constituent edges is derived. These results have fundamental importance as well as specific applications, and they promise new physical insights into diffraction-related phenomena. The usefulness of the formulations is illuminated in the context of a virtual source theory that accounts for two transverse dimensions. This application permits calculation of fractal unstable-resonator modes of arbitrary order and unprecedented accuracy.

  19. On the Asymptotics of Bessel Functions in the Fresnel Regime

    DTIC Science & Technology

    2014-07-10

    between the solutions u, v of (1) and the corresponding phase function is given by the formula α′(z) = W u2(z) + v2(z) , (8) with W the (constant...We introduce a version of the asymptotic expansions for Bessel functions Jν(z), Yν(z) that is valid whenever |z| > ν (which is deep in the Fresnel... function , and uses classical formulas to obtain an asymptotic expansion for this function ; this in turn leads to both an analytical tool and a nu

  20. Lensing smoothing of BAO wiggles

    NASA Astrophysics Data System (ADS)

    Di Dio, Enea

    2017-03-01

    We study non-perturbatively the effect of the deflection angle on the BAO wiggles of the matter power spectrum in real space. We show that from redshift z~2 this introduces a dispersion of roughly 1 Mpc at BAO scale, which corresponds approximately to a 1% effect. The lensing effect induced by the deflection angle, which is completely geometrical and survey independent, smears out the BAO wiggles. The effect on the power spectrum amplitude at BAO scale is about 0.1 % for z~2 and 0.2 % for z~4. We compare the smoothing effects induced by the lensing potential and non-linear structure formation, showing that the two effects become comparable at z ~ 4, while the lensing effect dominates for sources at higher redshifts. We note that this effect is not accounted through BAO reconstruction techniques.

  1. Beam bending via plasmonic lenses.

    PubMed

    Zhao, Yanhui; Lin, Sz-Chin Steven; Nawaz, Ahmad Ahsan; Kiraly, Brian; Hao, Qingzhen; Liu, Yanjun; Huang, Tony Jun

    2010-10-25

    We have designed and characterized three different types of plasmonic lenses that cannot only focus, but can also bend electromagnetic (EM) waves. The bending effect is achieved by constructing an asymmetric phase front caused by varying phase retardations in EM waves as they pass through a plasmonic lens. With an incident wave normal to the lens surface, light bends up to 8° off the axial direction. The optical wave propagation was numerically investigated using the finite-difference time-domain (FDTD) method. Simulation results show that the proposed plasmonic lenses allow effective beam bending under both normal and tilted incidence. With their relatively large bending range and capability to perform in the far field, the plamsonic lenses described in this article could be valuable in applications such as photonic communication and plasmonic circuits.

  2. Contact lenses for infant aphakia.

    PubMed Central

    Amaya, L G; Speedwell, L; Taylor, D

    1990-01-01

    We prospectively studied for three years the optical correction by contact lenses of 83 aphakic infants (141 eyes) who generally also had systemic and other ocular anomalies: 85% of the patients tolerated the lens wear for the whole study period. Complications occurred in 46 eyes and led to cessation of lens wear in two cases. Ten patients abandoned the lenses for other reasons. Thirty-four eyes needed subsequent intraocular surgery, mostly minor, and nine patients had strabismus surgery. Contact lenses are a versatile, safe, successful, and cost effective treatment for aphakia in infancy against which, before their widespread introduction for primary optical correction of infant aphakia, other methods of aphakic treatment need to be compared. PMID:2322512

  3. Tuning Gravitationally Lensed Standard Sirens

    NASA Astrophysics Data System (ADS)

    Jönsson, J.; Goobar, A.; Mörtsell, E.

    2007-03-01

    Gravitational waves emitted by chirping supermassive black hole binaries could in principle be used to obtain very accurate distance determinations. Provided they have an electromagnetic counterpart from which the redshift can be determined, these standard sirens could be used to build a high-redshift Hubble diagram. Errors in the distance measurements will most likely be dominated by gravitational lensing. We show that the (de)magnification due to inhomogeneous foreground matter will increase the scatter in the measured distances by a factor of ~10. We propose to use optical and IR data of the foreground galaxies to minimize the degradation from weak lensing. We find that the net effect of correcting the estimated distances for lensing is comparable to increasing the sample size by a factor of 3 when using the data to constrain cosmological parameters.

  4. Holography at the U.S. Army Research Laboratory: Development of Hologram Transform Equations using the Fresnel Approximation

    DTIC Science & Technology

    2012-09-01

    assumptions change the Helmholtz-Kirchhoff equation to the Kirchhoff diffraction integral. Finally, the Fresnel and Fraunhofer approximations, which deal...23) This result is called the Fresnel approximation to the Kirchhoff diffraction integral. A final...Holography at the U.S. Army Research Laboratory: Development of Hologram Transform Equations using the Fresnel Approximation by Karl K

  5. Design and fabrication of linear Fresnel zone plates used for microspectrometer

    NASA Astrophysics Data System (ADS)

    Liu, Ruicong; Liu, Yuanyuan; Yang, Fuhua

    2016-10-01

    Fresnel zone plate is a classic optical element that however can be used as the core spectral component of micro-spectrometer, which optical path volume can be decreased to 1mm3. After passing through the Fresnel zone plate, monochromatic lights of different wavelengths will expand to spectrum because of their different focal length. We designed eight kinds of linear half zone plates to get different focal lengths and spectral performance. In the process of fabrication, we used the electron beam lithography and inductively coupled plasma (ICP) etching to produce the Fresnel zone plates. Finally, performances of Fresnel zone plates were examined by beam-split experiments. After comparison, the simulation conclusion in reference that the number of bands of Fresnel zone plates will affect the final appearance of the spectrum was verified.

  6. Results and Comparison from the SAM Linear Fresnel Technology Performance Model: Preprint

    SciTech Connect

    Wagner, M. J.

    2012-04-01

    This paper presents the new Linear Fresnel technology performance model in NREL's System Advisor Model. The model predicts the financial and technical performance of direct-steam-generation Linear Fresnel power plants, and can be used to analyze a range of system configurations. This paper presents a brief discussion of the model formulation and motivation, and provides extensive discussion of the model performance and financial results. The Linear Fresnel technology is also compared to other concentrating solar power technologies in both qualitative and quantitative measures. The Linear Fresnel model - developed in conjunction with the Electric Power Research Institute - provides users with the ability to model a variety of solar field layouts, fossil backup configurations, thermal receiver designs, and steam generation conditions. This flexibility aims to encompass current market solutions for the DSG Linear Fresnel technology, which is seeing increasing exposure in fossil plant augmentation and stand-alone power generation applications.

  7. Fabrication of nanoscale electrostatic lenses

    NASA Astrophysics Data System (ADS)

    Sinno, I.; Sanz-Velasco, A.; Kang, S.; Jansen, H.; Olsson, E.; Enoksson, P.; Svensson, K.

    2010-09-01

    The fabrication of cylindrical multi-element electrostatic lenses at the nanoscale presents a challenge; they are high-aspect-ratio structures that should be rotationally symmetric, well aligned and freestanding, with smooth edges and flat, clean surfaces. In this paper, we present the fabrication results of a non-conventional process, which uses a combination of focused gallium ion-beam milling and hydrofluoric acid vapor etching. This process makes it possible to fabricate nanoscale electrostatic lenses down to 140 nm in aperture diameter and 4.2 µm in column length, with a superior control of the geometry as compared to conventional lithography-based techniques.

  8. Performance improvement of Fresnel beamforming using dual apodization with cross-correlation.

    PubMed

    Nguyen, Man M; Yen, Jesse T

    2013-03-01

    Fresnel beamforming is a beamforming method that has a delay profile with a shape similar to a physical Fresnel lens. With 4 to 8 transmit channels, 2 receive channels, and a network of single-pole/single-throw switches, Fresnel beamforming can reduce the size, cost, and complexity of a beamformer. The performance of Fresnel beamforming is highly dependent on focal errors resulting from phase wraparound and quantization of its delay profile. Previously, we demonstrated that the performance of Fresnel beamforming relative to delayand- sum (DAS) beamforming is comparable for linear arrays at f-number = 2 and 50% bandwidth. However, focal errors for Fresnel beamforming are larger because of larger path length differences between elements, as in the case of curvilinear arrays compared with linear arrays. In this paper, we present the concept and performance evaluation of Fresnel beamforming combined with a novel clutter suppression method called dual apodization with cross-correlation (DAX) for curvilinear arrays. The contrast-to-noise ratios (CNRs) of Fresnel beamforming followed by DAX are highest at f-number = 3. At f-number = 3, the experimental results show that using DAX, the CNR for Fresnel beamforming improves from 3.7 to 10.6, compared with a CNR of 5.2 for DAS beamforming. Spatial resolution is shown to be unaffected by DAX. At f-number = 3, the lateral beamwidth and axial pulse length for Fresnel beamforming with DAX are 1.44 and 1.00 mm larger than those for DAS beamforming (about 14% and 21% larger), respectively. These experimental results are in good agreement with simulation results.

  9. Performance Improvement of Fresnel Beamforming Using Dual Apodization With Cross-Correlation

    PubMed Central

    Nguyen, Man M.; Yen, Jesse T.

    2013-01-01

    Fresnel beamforming is a beamforming method that has a delay profile with a shape similar to a physical Fresnel lens. With 4 to 8 transmit channels, 2 receive channels, and a network of single-pole/single-throw switches, Fresnel beamforming can reduce the size, cost, and complexity of a beam-former. The performance of Fresnel beamforming is highly dependent on focal errors resulting from phase wraparound and quantization of its delay profile. Previously, we demonstrated that the performance of Fresnel beamforming relative to delay-and-sum (DAS) beamforming is comparable for linear arrays at f-number = 2 and 50% bandwidth. However, focal errors for Fresnel beamforming are larger because of larger path length differences between elements, as in the case of curvilinear arrays compared with linear arrays. In this paper, we present the concept and performance evaluation of Fresnel beamforming combined with a novel clutter suppression method called dual apodization with cross-correlation (DAX) for curvilinear arrays. The contrast-to-noise ratios (CNRs) of Fresnel beamforming followed by DAX are highest at f-number = 3. At f-number = 3, the experimental results show that using DAX, the CNR for Fresnel beamforming improves from 3.7 to 10.6, compared with a CNR of 5.2 for DAS beamforming. Spatial resolution is shown to be unaffected by DAX. At f-number = 3, the lateral beamwidth and axial pulse length for Fresnel beamforming with DAX are 1.44 and 1.00 mm larger than those for DAS beamforming (about 14% and 21% larger), respectively. These experimental results are in good agreement with simulation results. PMID:23475913

  10. Lensing signals from spin-2 perturbations

    SciTech Connect

    Adamek, Julian; Durrer, Ruth; Tansella, Vittorio E-mail: ruth.durrer@unige.ch

    2016-01-01

    We compute the angular power spectra of the E-type and B-type lensing potentials for gravitational waves from inflation and for tensor perturbations induced by scalar perturbations. We derive the tensor-lensed CMB power spectra for both cases. We also apply our formalism to determine the linear lensing potential for a Bianchi I spacetime with small anisotropy.

  11. N-body lensed CMB maps: lensing extraction and characterization

    NASA Astrophysics Data System (ADS)

    Antolini, Claudia; Fantaye, Yabebal; Martinelli, Matteo; Carbone, Carmelita; Baccigalupi, Carlo

    2014-02-01

    We reconstruct shear maps and angular power spectra from simulated weakly lensed total intensity (TT) and polarised (EB) maps of the Cosmic Microwave Background (CMB) anisotropies, obtained using Born approximated ray-tracing through the N-body simulated Cold Dark Matter (CDM) structures in the Millennium Simulations (MS). We compare the recovered signal with the ΛCDM prediction, on the whole interval of angular scales which is allowed by the finite box size, extending from the degree scale to the arcminute, by applying a quadratic estimator in the flat sky limit; we consider PRISM-like instrumental specification for future generation CMB satellites, corresponding to arcminute angular resolution of 3.2' and sensitivity of 2.43 μK-arcmin. The noise contribution in the simulations closely follows the estimator prediction, becoming dominated by limits in the angular resolution for the EB signal, at l simeq 1500. The recovered signal shows no visible departure from predictions of the weak lensing power within uncertainties, when considering TT and EB data singularly. In particular, the reconstruction precision reaches the level of a few percent in bins with Δl simeq 100 in the angular multiple interval 1000lesssimllesssim2000 for T, and about 10% for EB. Within the adopted specifications, polarisation data do represent a significant contribution to the lensing shear, which appear to faithfully trace the underlying N-body structure down to the smallest angular scales achievable with the present setup, validating at the same time the latter with respect to semi-analytical predictions from ΛCDM cosmology at the level of CMB lensing statistics. This work demonstrates the feasibility of CMB lensing studies based on large scale simulations of cosmological structure formation in the context of the current and future high resolution and sensitivity CMB experiment.

  12. N-body lensed CMB maps: lensing extraction and characterization

    SciTech Connect

    Antolini, Claudia; Martinelli, Matteo; Baccigalupi, Carlo; Fantaye, Yabebal; Carbone, Carmelita E-mail: y.t.fantaye@astro.uio.no E-mail: carmelita.carbone@brera.inaf.it

    2014-02-01

    We reconstruct shear maps and angular power spectra from simulated weakly lensed total intensity (TT) and polarised (EB) maps of the Cosmic Microwave Background (CMB) anisotropies, obtained using Born approximated ray-tracing through the N-body simulated Cold Dark Matter (CDM) structures in the Millennium Simulations (MS). We compare the recovered signal with the ΛCDM prediction, on the whole interval of angular scales which is allowed by the finite box size, extending from the degree scale to the arcminute, by applying a quadratic estimator in the flat sky limit; we consider PRISM-like instrumental specification for future generation CMB satellites, corresponding to arcminute angular resolution of 3.2' and sensitivity of 2.43 μK-arcmin. The noise contribution in the simulations closely follows the estimator prediction, becoming dominated by limits in the angular resolution for the EB signal, at ℓ ≅ 1500. The recovered signal shows no visible departure from predictions of the weak lensing power within uncertainties, when considering TT and EB data singularly. In particular, the reconstruction precision reaches the level of a few percent in bins with Δℓ ≅ 100 in the angular multiple interval 1000∼<ℓ∼<2000 for T, and about 10% for EB. Within the adopted specifications, polarisation data do represent a significant contribution to the lensing shear, which appear to faithfully trace the underlying N-body structure down to the smallest angular scales achievable with the present setup, validating at the same time the latter with respect to semi-analytical predictions from ΛCDM cosmology at the level of CMB lensing statistics. This work demonstrates the feasibility of CMB lensing studies based on large scale simulations of cosmological structure formation in the context of the current and future high resolution and sensitivity CMB experiment.

  13. Performance comparison of Fresnel-based concentrator arrays

    NASA Astrophysics Data System (ADS)

    Mohedano, Rubén; Cvetkovic, Aleksandra; Benítez, Pablo; Zamora, Pablo; Miñano, Juan C.; Chaves, Julio; Hernandez, Maikel; Buljan, Marina; Vilaplana, Juan

    2010-08-01

    At module level (one single solar cell), the Fresnel-Köhler (FK) concentrator comprises a perfect irradiance uniformity along with quite high concentration-acceptance angle product. At the same time, it maintains the efficiency/simplicity of other Fresnel-based concentrators. In this work we will show the FK concentrator has loose manufacturing tolerances as well. All these facts, along with the pill-box shape of its transmission curve, permit an enhanced performance of this device, compared to its competitors, at array level, because the system is more insensitive to manufacturing errors, and current mismatch is less likely to occur. Or the same performance can be achieved at a lower cost, exhausting the tolerance budget by using inexpensive fabrication techniques. Depending on the concentrator, the actual power delivered by an array might drop significantly with respect to the sum of the power delivered by single modules. Under certain circumstances, the FK can reach a 1-10% electrical efficiency increase with regards to other concentrators sharing the same technology.

  14. Fresnel diffraction of fractal grating and self-imaging effect.

    PubMed

    Wang, Junhong; Zhang, Wei; Cui, Yuwei; Teng, Shuyun

    2014-04-01

    Based on the self-similarity property of fractal, two types of fractal gratings are produced according to the production and addition operations of multiple periodic gratings. Fresnel diffractions of fractal grating are analyzed theoretically, and the general mathematic expressions of the diffraction intensity distributions of fractal grating are deduced. The gray-scale patterns of the 2D diffraction distributions of fractal grating are provided through numerical calculations. The diffraction patterns take on the periodicity along the longitude and transverse directions. The 1D diffraction distribution at some certain distances shows the same structure as the fractal grating. This indicates that the self-image of fractal grating is really formed in the Fresnel diffraction region. The experimental measurement of the diffraction intensity distribution of fractal grating with different fractal dimensions and different fractal levels is performed, and the self-images of fractal grating are obtained successfully in experiments. The conclusions of this paper are helpful for the development of the application of fractal grating.

  15. Optical refractometry based on Fresnel diffraction from a phase wedge.

    PubMed

    Tavassoly, M Taghi; Saber, Ahad

    2010-11-01

    A method that utilizes the Fresnel diffraction of light from the phase step formed by a transparent wedge is introduced for measuring the refractive indices of transparent solids, liquids, and solutions. It is shown that, as a transparent wedge of small apex angle is illuminated perpendicular to its surface by a monochromatic parallel beam of light, the Fresnel fringes, caused by abrupt change in refractive index at the wedge lateral boundary, are formed on a screen held perpendicular to the beam propagation direction. The visibility of the fringes varies periodically between zero and 1 in the direction normal to the wedge apex. For a known or measured apex angle, the wedge refractive index is obtained by measuring the period length by a CCD. To measure the refractive index of a transparent liquid or solution, the wedge is installed in a transparent rectangle cell containing the sample. Then, the cell is illuminated perpendicularly and the visibility period is measured. By using modest optics, one can measure the refractive index at a relative uncertainty level of 10(-5). There is no limitation on the refractive index range. The method can be applied easily with no mechanical manipulation. The measuring apparatus can be very compact with low mechanical and optical noises.

  16. Using new optical materials and DOE in low-cost lenses for uncooled IR cameras

    NASA Astrophysics Data System (ADS)

    Bacchus, Jean-Marie

    2004-02-01

    Angénieux recently developed a low cost 100 mm F/1.25 lens for uncooled IR cameras. It is made of only 2 elements, thanks to the use of GASIR glass (Umicore product) and a diffractive surface. With regard to its equivalent in germanium, it offers similar performances, for a much lower cost due to the price of the optical material, molding, and no need for athermalisation. This lens can be used with new light-weighted night vision goggle ELVIR developed by Thales-Angénieux. We plan to also use GASIR in low cost zoom lenses for uncooled cameras. Starting with these examples, we will compare different available optical materials for IR, their characteristics, and respective advantages and drawbacks. We will deduct from it from rules of use for these materials, depending upon the envisaged use, spectral bandwidth and number of items manufactured.

  17. Optics Demonstrations Using Cylindrical Lenses

    ERIC Educational Resources Information Center

    Ivanov, Dragia; Nikolov, Stefan

    2015-01-01

    In this paper we consider the main properties of cylindrical lenses and propose several demonstrational experiments that can be performed with them. Specifically we use simple glasses full of water to demonstrate some basic geometrical optics principles and phenomena. We also present some less standard experiments that can be performed with such…

  18. Towards noiseless gravitational lensing simulations

    NASA Astrophysics Data System (ADS)

    Angulo, Raul E.; Chen, Ruizhu; Hilbert, Stefan; Abel, Tom

    2014-11-01

    The microphysical properties of the dark matter (DM) particle can, in principle, be constrained by the properties and abundance of substructures in galaxy clusters, as measured through strong gravitational lensing. Unfortunately, there is a lack of accurate theoretical predictions for the lensing signal of these substructures, mainly because of the discreteness noise inherent to N-body simulations. Here, we present a method, dubbed as Recursive-TCM, that is able to provide lensing predictions with an arbitrarily low discreteness noise. This solution is based on a novel way of interpreting the results of N-body simulations, where particles simply trace the evolution and distortion of Lagrangian phase-space volume elements. We discuss the advantages and limitations of this method compared to the widely used density estimators based on cloud-in-cells and adaptive-kernel smoothing. Applying the new method to a cluster-sized DM halo simulated in warm and cold DM scenarios, we show how the expected differences in their substructure population translate into differences in convergence and magnification maps. We anticipate that our method will provide the high-precision theoretical predictions required to interpret and fully exploit strong gravitational lensing observations.

  19. Gravitational Lenses in the Classroom

    ERIC Educational Resources Information Center

    Ros, Rosa M.

    2008-01-01

    It is not common to introduce current astronomy in school lessons. This article presents a set of experiments about gravitational lenses. It is normal to simulate them by means of computers, but it is very simple to simulate similar effects using a drinking glass full of liquid or using only the glass base. These are, of course, cheap and easy…

  20. The Optical Gravitational Lensing Experiment

    NASA Technical Reports Server (NTRS)

    Udalski, A.; Szymanski, M.; Kaluzny, J.; Kubiak, M.; Mateo, Mario

    1992-01-01

    The technical features are described of the Optical Gravitational Lensing Experiment, which aims to detect a statistically significant number of microlensing events toward the Galactic bulge. Clusters of galaxies observed during the 1992 season are listed and discussed and the reduction methods are described. Future plans are addressed.

  1. Gravitational Lensing of Supernova Neutrinos

    SciTech Connect

    Mena, Olga; Mocioiu, Irina; Quigg, Chris; /Fermilab

    2006-10-01

    The black hole at the center of the galaxy is a powerful lens for supernova neutrinos. In the very special circumstance of a supernova near the extended line of sight from Earth to the galactic center, lensing could dramatically enhance the neutrino flux at Earth and stretch the neutrino pulse.

  2. Thermal lensing of laser materials

    NASA Astrophysics Data System (ADS)

    Davis, Mark J.; Hayden, Joseph S.

    2014-10-01

    This paper focuses on the three main effects that can induce wave-front distortion due to thermal lensing in laser gain media: 1) thermo-optic (dn/dT); 2) stress-optic; and 3) surface deformation (e.g., "end-bulging" of a laser rod). Considering the simple case of a side-pumped cylindrical rod which is air- or water-cooled along its length, the internal temperature distribution has long been known to assume a simple parabolic profile. Resulting from this are two induced refractive index variations due to thermo-optic and stress-optic effects that also assume a parabolic profile, but generally not of the same magnitude, nor even of the same sign. Finally, a small deformation on the rod ends can induce a small additional lensing contribution. We had two goals in this study: a) use finite-element simulations to verify the existing analytical expressions due to Koechner1 and Foster and Osterink; and b) apply them to glasses from the SCHOTT laser glass portfolio. The first goal was a reaction to more recent work by Chenais et al. who claimed Koechner made an error in his analysis with regard to thermal stress, throwing into doubt conclusions within studies since 1970 which made use of his equations. However, our re-analysis of their derivations, coupled with our FE modeling, confirmed that the Koechner and Foster and Osterink treatments are correct, and that Chenais et al. made mistakes in their derivation of the thermally-induced strain. Finally, for a nominal laser rod geometry, we compared the thermally-induced optical distortions in LG-680, LG-750, LG-760, LG-770, APG-1, and APG-2. While LG-750, -760, and -770 undergo considerable thermo-optic lensing, their stress-optic lensing is nearly of the same magnitude but of opposite sign, leading to a small total thermal lensing signature.

  3. EDITORIAL: Focus on Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Jain, Bhuvnesh

    2007-11-01

    Gravitational lensing emerged as an observational field following the 1979 discovery of a doubly imaged quasar lensed by a foreground galaxy. In the 1980s and '90s dozens of other multiply imaged systems were observed, as well as time delay measurements, weak and strong lensing by galaxies and galaxy clusters, and the discovery of microlensing in our galaxy. The rapid pace of advances has continued into the new century. Lensing is currently one of best techniques for finding and mapping dark matter over a wide range of scales, and also addresses broader cosmological questions such as understanding the nature of dark energy. This focus issue of New Journal of Physics presents a snapshot of current research in some of the exciting areas of lensing. It provides an occasion to look back at the advances of the last decade and ahead to the potential of the coming years. Just about a decade ago, microlensing was discovered through the magnification of stars in our galaxy by invisible objects with masses between that of Jupiter and a tenth the mass of the Sun. Thus a new component of the mass of our galaxy, dubbed MACHOs, was established (though a diffuse, cold dark matter-like component is still needed to make up most of the galaxy mass). More recently, microlensing led to another exciting discovery—of extra-solar planets with masses ranging from about five times that of Earth to that of Neptune. We can expect many more planets to be discovered through ongoing surveys. Microlensing is the best technique for finding Earth mass planets, though it is not as productive overall as other methods and does not allow for follow up observations. Beyond planet hunting, microlensing has enabled us to observe previously inaccessible systems, ranging from the surfaces of other stars to the accretion disks around the black holes powering distant quasars. Galaxies and galaxy clusters at cosmological distances can produce dramatic lensing effects: multiple images of background galaxies

  4. Key results of the mini-dome Fresnel lens concentrator array development program under recently completed NASA and SDIO SBIR projects

    NASA Technical Reports Server (NTRS)

    Oneill, Mark J.; Piszczor, Michael F.; Fraas, Lewis M.

    1991-01-01

    Since 1986, ENTECH and the NASA Lewis Research Center have been developing a new photovoltaic concentrator system for space power applications. The unique refractive system uses small, dome shaped Fresnel lenses to focus sunlight onto high efficiency photovoltaic concentrator cells which use prismatic cell covers to further increase their performance. Highlights of the five-year development include near Air Mass Zero (AM0) Lear Jet flight testing of mini-dome lenses (90 pct. net optical efficiency achieved); tests verifying sun-pointing error tolerance with negligible power loss; simulator testing of prism-covered GaAs concentrator cells (24 pct. AM0 efficiency); testing of prism-covered Boeing GaAs/GaSb tandem cells (31 pct. AM0 efficiency); and fabrication and outdoor testing of a 36-lens/cell element panel. These test results have confirmed previous analytical predictions which indicate substantial performance improvements for this technology over current array systems. Based on program results to date, it appears than an array power density of 300 watts/sq m and a specific power of 100 watts/kg can be achieved in the near term. All components of the array appear to be readily manufacturable from space-durable materials at reasonable cost. A concise review is presented of the key results leading to the current array, and further development plans for the future are briefly discussed.

  5. Fresnel drag of light by a moving nonlinear and nanostructured dielectric medium

    SciTech Connect

    Peiponen, Kai-Erik; Gornov, Evgeny

    2007-12-15

    The Fresnel drag is viewed in the frame of nonlinear and/or nanostructured uniformly moving media. It is shown that in the case of intense light pulse interaction with an optically nonlinear medium the relativistic frequency chirp due to self-phase modulation is smaller than in the rest frame. In the case of light interaction with optically linear or nonlinear nanostructured medium the Fresnel drag depends on the effective refractive index of the medium. While the nanostructures are in a liquid matrix the drag can be controlled by the fill fraction of the inclusions. As an example the Fresnel drag for optically linear Bruggeman liquid is considered.

  6. Solar-pumped 80 W laser irradiated by a Fresnel lens.

    PubMed

    Ohkubo, Tomomasa; Yabe, Takashi; Yoshida, Kunio; Uchida, Shigeaki; Funatsu, Takayuki; Bagheri, Behgol; Oishi, Takehiro; Daito, Kazuya; Ishioka, Manabu; Nakayama, Yuichirou; Yasunaga, Norihito; Kido, Kouichirou; Sato, Yuji; Baasandash, Choijil; Kato, Kiyoshi; Yanagitani, Takagimi; Okamoto, Yoshiaki

    2009-01-15

    A solar-pumped 100 W class laser that features high efficiency and low cost owing to the use of a Fresnel lens and a chromium codoped neodymium YAG ceramic laser medium was developed. A laser output of about 80 W was achieved with combination of a 4 m(2) Fresnel lens and a pumping cavity as a secondary power concentrator. This output corresponds to 4.3% of conversion efficiency from solar power into laser, and the maximum output from a unit area of Fresnel lens was 20 W/m(2), which is 2.8 times larger than previous results with mirror-type concentrator.

  7. Simulation and study of Fresnel diffraction for arbitrary two-dimensional apertures

    SciTech Connect

    Dauger, D.E.

    1996-11-01

    A stable, efficient algorithm to calculate numerically a Fresnel diffraction image, given any two-dimensional aperture or obstacle, is introduced. The algorithm predicts both the intensity and relative phase of the image. An alternate faster algorithm is presented for a limited class of apertures. Also examined are images formed from a variety of aperture shapes. Using this computational technique, plots on the complex plane are shown to give insight into Fresnel diffraction. With additional modifications to accept parameters from an experimental apparatus, the algorithms model Fresnel diffraction for laboratory situations. In addition, the algorithms are suitable for numerical implementation on personal computers. {copyright} {ital 1996 American Institute of Physics.}

  8. A Fresnel collector process heat experiment at Capitol Concrete Products

    NASA Technical Reports Server (NTRS)

    Hauger, J. S.

    1981-01-01

    An experiment is planned, conducted and evaluated to determine the feasibility of using a Power Kinetics' Fresnel concentrator to provide process heat in an industrial environment. The plant provides process steam at 50 to 60 psig to two autoclaves for curing masonry blocks. When steam is not required, the plant preheats hot water for later use. A second system is installed at the Jet Propulsion Laboratory parabolic dish test site for hardware validation and experiment control. Experiment design allows for the extrapolation of results to varying demands for steam and hot water, and includes a consideration of some socio-technical factors such as the impact on production scheduling of diurnal variations in energy availability.

  9. Verification of Fresnel lens in high concentration photovoltaic system

    NASA Astrophysics Data System (ADS)

    Wei, An-Chi; Sze, Jyh-Rou; Chern, Jyh-Long

    2012-10-01

    An approach using micro lens arrays to confine the cone angle of light source in a solar simulator has been proposed to verify the Fresnel lens in a high concentration photovoltaic (HCPV) system. Compared with other three prior arts by the computer simulation, the proposed method had the characteristics of the better approximation to the direct normal insolation and the low cost. Also, to ensure the erection of the evaluation system, the tolerance of lens alignment has been analyzed. The results showed that to maintain at least the 50% of the maximum luminous flux incident on the solar cell, the transverse and longitudinal tolerances of ±1.4 mm and ±4 mm, respectively, were required.

  10. Introducing CFD in the optical simulation of linear Fresnel collectors

    NASA Astrophysics Data System (ADS)

    Moghimi, M. A.; Rungasamy, A.; Craig, K. J.; Meyer, J. P.

    2016-05-01

    This paper seeks to determine whether the Finite Volume method within a commercially available Computational Fluid Dynamics (CFD) solver (ANSYS Fluent) can model radiation with comparable accuracy to a Monte Carlo ray-tracing software package (SolTrace). A detailed investigation was performed into modeling techniques that can be used to significantly reduce the optical errors traditionally associated with CFD modeling of radiation false scattering and ray effect using a simple optical test case. The strategies formulated in the first part of this paper were used to model a variety of Linear Fresnel Collector Concentrating Solar Power Plants. This paper shows that commercial CFD packages yield accurate results for line focusing concentrating solar applications and simple geometries, validating its use in an integrated environment where both optical and thermal performance of these plants can be simulated and optimized.

  11. A tunable piezoelectric Fresnel mirror for high-speed lineshaping

    NASA Astrophysics Data System (ADS)

    Brunne, Jens; Wapler, Matthias C.; Grunwald, Ruediger; Wallrabe, Ulrike

    2013-11-01

    We present the first tunable v-shaped mirror, also known as Fresnel mirror, that may be used to generate a quasi-nondiffracting line pattern, for example for applications in laser lithography or nanomachining with femtosecond lasers. The aperture of the device is 5 mm with a surface flatness of better than λ/10, and the range of the tilting angle is 1.3-38 mrad, resulting in a fringe spacing of 123 μm down to 4.2 μm for red light at 633 nm. In contrast to usual cantilever-comb setups, the mirrors are supported on a PDMS layer and tilted by a single piezoelectric actuator, providing a high resonance frequency of 5.1 kHz. The device is fabricated using laser rapid prototyping of silicon and a casting processes of soft polymers. We show the static and dynamic characterization of the mirror and the verification of the optical functionality.

  12. Bi-functional Fresnel zone plate from transformation optics

    NASA Astrophysics Data System (ADS)

    Yang, Rui; Wang, Zhaoxu; Su, He; Yang, Yinan; Lei, Zhenya

    2015-07-01

    Instead of reshaping the standard parabolic reflector or the hyperbolic lens to propose their planar counterparts, here we choose to flatten the primary spherical wave front based on the quasi-conformal transformation optics. Ray traces, travelling from the source to the transformed planar surface, can thus be maintained of the equal electrical path length in terms of the transformation-optics Fresnel zone plate. Due to the symmetrical feature of our transformation setup, the proposed device would readily possess dual functionalities in the light focusing and collimation that can either be applied to a reflector when incorporated with a plane mirror or directly employed as a standalone lens according to the principle of the image theory.

  13. Morphology of the scattering target: Fresnel and turbulent mechanisms

    NASA Technical Reports Server (NTRS)

    Rottger, J.

    1983-01-01

    Further studies of VHF radar signals from the troposphere and stratosphere revealed not only scattering from isotropic turbulence at scales of half the radar wavelength but also partial or Fresnel reflection or scattering from horizontally stratified temperature discontinuities. Proof for this observation was given by the large spatial and temporal coherence of radar signals. Thin structures, particularly in the stratosphere, may be persistent over some ten seconds, which is longer than the coherence time of 3 m scale turbulence in the stratosphere. The vertical thickness of the structures was estimated to be much thinner than 150 m. Observations over a longer time period indicate that these fine scale structures or sheets are clumped together forming patches or ensembles of mostly downward sloping structures.

  14. Development of background reduced Fresnel phase zone plate

    SciTech Connect

    Tamari, Yohei; Azechi, Hiroshi

    2004-10-01

    In study of hot and dense plasma, a high spatial resolution (a few microns) x-ray imaging is very important to observe these plasmas. The Fresnel phase zone plate (FPZP) consists of alternately material and transparent circular annuli placed concentrically, which image x rays using diffraction x rays from all annuli. FPZP have imaged 4.7-4.77 keV x rays with 2.2 {mu}m spatial resolution. However FPZP has a problem that background level is comparable to signal level. In subtraction of background, the error of 10% is caused. For the accurate background subtraction, we designed new FPZP, which consist of three {beta} layers of a transparent zone and two material zones. The new design FPZP parameters (thickness of material zones, each zone width) have been optimized, and in that optimum design signal-to-background ratio is 4 times better than conventional two layers FPZP.

  15. Layered holographic stereogram based on inverse Fresnel diffraction.

    PubMed

    Zhang, Hao; Zhao, Yan; Cao, Liangcai; Jin, Guofan

    2016-01-20

    We propose an efficient algorithm using layered holographic stereogram for three-dimensional (3D) computer-generated holograms. The hologram is spatially partitioned into multiple holographic elements (hogels) to provide the occlusion effect and motion parallax by use of multiple viewpoint rendering. Each hogel is calculated with inverse Fresnel diffraction by slicing the viewing frustum according to the depth image. The sliced layers can provide accurate depth cues for reconstruction since the geometric information of the 3D scene is faithfully matched. The algorithm is compatible with computer graphics rendering techniques and robust for holograms with different parameters. When the hogel size equals 1 mm, the signal-to-noise ratio of the diffraction calculation is above 39 dB with a propagation distance longer than 10 mm. Numerical simulations and optical experiments have demonstrated that the proposed method can reconstruct quality 3D images with reduced computational load.

  16. Fresnel particle tracing in three dimensions using diffraction phase microscopy.

    PubMed

    Park, Yongkeun; Popescu, Gabriel; Badizadegan, Kamran; Dasari, Ramachandra R; Feld, Michael S

    2007-04-01

    We have developed a novel experimental technique for tracking small particles in three dimensions with nanometer accuracy. The longitudinal positioning of a micrometer-sized particle is determined by using the Fresnel approximation to describe the transverse distribution of the wavefront that originated in the particle. The method utilizes the high-sensitivity quantitative phase imaging capability of diffraction phase microscopy recently developed in our laboratory. We demonstrate the principle of the technique with experiments on Brownian particles jittering in water both in bulk and in the vicinity of a boundary. The particles are localized in space within an error cube of 20 nm x 20 nm x 20 nm for a 33 Hz acquisition rate and 20s recording time.

  17. Spectral transfer from phase to intensity in Fresnel diffraction

    NASA Astrophysics Data System (ADS)

    Hahn, S.; Müller, Y.; Hofmann, R.; Moosmann, J.; Öktem, O.; Helfen, L.; Guigay, J.-P.; van de Kamp, Th.; Baumbach, T.

    2016-05-01

    We analyze theoretically and investigate experimentally the transfer of phase to intensity power spectra of spatial frequencies through free-space Fresnel diffraction. Depending on λ z (where λ is the wavelength and z is the free-space propagation distance) and the phase-modulation strength S , we demonstrate that for multiscale and broad phase spectra critical behavior transmutes a quasilinear to a nonlinear diffractogram except for low frequencies. On the contrary, a single-scale and broad phase spectrum induces a critical transition in the diffractogram at low frequencies. In both cases, identifying critical behavior encoded in the intensity power spectra is of fundamental interest because it exhibits the limits of perturbative power counting but also guides resolution and contrast optimization in propagation-based, single-distance, phase-contrast imaging, given certain dose and coherence constraints.

  18. Fresnel diffraction in the case of an inclined image plane.

    PubMed

    Modregger, Peter; Lübbert, Daniel; Schäfer, Peter; Köhler, Rolf; Weitkamp, Timm; Hanke, Michael; Baumbach, Tilo

    2008-03-31

    An extension of the theoretical formalism of Fresnel diffraction to the case of an inclined image plane is proposed. The resulting numerical algorithm speeds up computation times by typically three orders of magnitude, thus opening the possibility of utilizing previously inapplicable image analysis algorithms for this special type of a non shift-invariant imaging system. This is exemplified by adapting an iterative phase retrieval algorithm developed for electron microscopy to the case of hard x-ray imaging with asymmetric Bragg reflection (the so-called "Bragg Magnifier"). Numerical simulations demonstrate the convergence and feasibility of the iterative phase retrieval algorithm for the case of x-ray imaging with the Bragg Magnifier.

  19. The shape of the CMB lensing bispectrum

    SciTech Connect

    Lewis, Antony; Challinor, Anthony; Hanson, Duncan E-mail: adc1000@ast.cam.ac.uk

    2011-03-01

    Lensing of the CMB generates a significant bispectrum, which should be detected by the Planck satellite at the 5-sigma level and is potentially a non-negligible source of bias for f{sub NL} estimators of local non-Gaussianity. We extend current understanding of the lensing bispectrum in several directions: (1) we perform a non-perturbative calculation of the lensing bispectrum which is ∼ 10% more accurate than previous, first-order calculations; (2) we demonstrate how to incorporate the signal variance of the lensing bispectrum into estimates of its amplitude, providing a good analytical explanation for previous Monte-Carlo results; and (3) we discover the existence of a significant lensing bispectrum in polarization, due to a previously-unnoticed correlation between the lensing potential and E-polarization as large as 30% at low multipoles. We use this improved understanding of the lensing bispectra to re-evaluate Fisher-matrix predictions, both for Planck and cosmic variance limited data. We confirm that the non-negligible lensing-induced bias for estimation of local non-Gaussianity should be robustly treatable, and will only inflate f{sub NL} error bars by a few percent over predictions where lensing effects are completely ignored (but note that lensing must still be accounted for to obtain unbiased constraints). We also show that the detection significance for the lensing bispectrum itself is ultimately limited to 9 sigma by cosmic variance. The tools that we develop for non-perturbative calculation of the lensing bispectrum are directly relevant to other calculations, and we give an explicit construction of a simple non-perturbative quadratic estimator for the lensing potential and relate its cross-correlation power spectrum to the bispectrum. Our numerical codes are publicly available as part of CAMB and LensPix.

  20. Tomography and weak lensing statistics

    SciTech Connect

    Munshi, Dipak; Coles, Peter; Kilbinger, Martin E-mail: peter.coles@astro.cf.ac.uk

    2014-04-01

    We provide generic predictions for the lower order cumulants of weak lensing maps, and their correlators for tomographic bins as well as in three dimensions (3D). Using small-angle approximation, we derive the corresponding one- and two-point probability distribution function for the tomographic maps from different bins and for 3D convergence maps. The modelling of weak lensing statistics is obtained by adopting a detailed prescription for the underlying density contrast that involves hierarchal ansatz and lognormal distribution. We study the dependence of our results on cosmological parameters and source distributions corresponding to the realistic surveys such as LSST and DES. We briefly outline how photometric redshift information can be incorporated in our results. We also show how topological properties of convergence maps can be quantified using our results.

  1. Seeing Patients Through Genetic Lenses

    PubMed Central

    FELCONE, LINDA HULL

    2005-01-01

    Biotechnology is changing how doctors ‘see’ patients and disease processes. Optical probes and computer-assisted genetic screening tools let researchers peer into the structure and functions of cellular proteins on a molecular level. Soon, this clearer vision of individual patients will be available in the clinic, making drug and biologic treatments safer. These new lenses will push medicine toward risk prediction and away from acute intervention. PMID:23393472

  2. Biomimetic Gradient Index (GRIN) Lenses

    DTIC Science & Technology

    2006-01-01

    optics include single lenses inspired by cephalopod (octopus) eyes and a three-lens, wide field of view, optical system for a surveillance sensor...camera. Details are easily resolv- able with the polymer lens. This lens system was installed on an Evolution unmanned aerial vehicle (UAV) with a...lens system was installed in an NRL Evolution UAV and used to record video images at a height of up to 1000 ft. The index gradients in the polymer

  3. RELICS: Reionization Lensing Cluster Survey

    NASA Astrophysics Data System (ADS)

    Coe, Dan A.; RELICS Team

    2017-01-01

    Hubble and Spitzer imaging programs observing galaxy cluster lenses have delivered some of the highest redshift galaxy candidates to date (z ~ 9 - 11, or 540 - 410 Myr after the Big Bang). These magnified galaxies are intrinsically faint, and thus more representative of the sources believed to be primarily responsible for reionization. Magnified galaxies are also observed brightly enough to be prime targets for detailed follow-up study with current and future observatories, including JWST. Building on the successes of CLASH and the Frontier Fields, we have begun RELICS, the Reionization Lensing Cluster Survey. By observing 41 massive clusters for the first time at infrared wavelengths, RELICS will deliver more of the best and brightest high-redshift candidates to the community in time for the November 2017 JWST GO Cycle 1 call for proposals. I will present our early results. I will also discuss prospects for JWST to follow-up known candidates and discover new galaxies at even higher redshifts (z > 11). The discovery efficiency gains from lensing will be even more pronounced at z > 11 if luminosity function faint end slopes are steeper than alpha ~ -2, as suggested by current models and observational extrapolations.

  4. Gravitational lensing in plasmic medium

    SciTech Connect

    Bisnovatyi-Kogan, G. S. Tsupko, O. Yu.

    2015-07-15

    The influence of plasma on different effects of gravitational lensing is reviewed. Using the Hamiltonian approach for geometrical optics in a medium in the presence of gravity, an exact formula for the photon deflection angle by a black hole (or another body with a Schwarzschild metric) embedded in plasma with a spherically symmetric density distribution is derived. The deflection angle in this case is determined by the mutual combination of different factors: gravity, dispersion, and refraction. While the effects of deflection by the gravity in vacuum and the refractive deflection in a nonhomogeneous medium are well known, the new effect is that, in the case of a homogeneous plasma, in the absence of refractive deflection, the gravitational deflection differs from the vacuum deflection and depends on the photon frequency. In the presence of a plasma nonhomogeneity, the chromatic refractive deflection also occurs, so the presence of plasma always makes gravitational lensing chromatic. In particular, the presence of plasma leads to different angular positions of the same image if it is observed at different wavelengths. It is discussed in detail how to apply the presented formulas for the calculation of the deflection angle in different situations. Gravitational lensing in plasma beyond the weak deflection approximation is also considered.

  5. Gravitational lensing in plasmic medium

    NASA Astrophysics Data System (ADS)

    Bisnovatyi-Kogan, G. S.; Tsupko, O. Yu.

    2015-07-01

    The influence of plasma on different effects of gravitational lensing is reviewed. Using the Hamiltonian approach for geometrical optics in a medium in the presence of gravity, an exact formula for the photon deflection angle by a black hole (or another body with a Schwarzschild metric) embedded in plasma with a spherically symmetric density distribution is derived. The deflection angle in this case is determined by the mutual combination of different factors: gravity, dispersion, and refraction. While the effects of deflection by the gravity in vacuum and the refractive deflection in a nonhomogeneous medium are well known, the new effect is that, in the case of a homogeneous plasma, in the absence of refractive deflection, the gravitational deflection differs from the vacuum deflection and depends on the photon frequency. In the presence of a plasma nonhomogeneity, the chromatic refractive deflection also occurs, so the presence of plasma always makes gravitational lensing chromatic. In particular, the presence of plasma leads to different angular positions of the same image if it is observed at different wavelengths. It is discussed in detail how to apply the presented formulas for the calculation of the deflection angle in different situations. Gravitational lensing in plasma beyond the weak deflection approximation is also considered.

  6. 30 CFR 18.30 - Windows and lenses.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Windows and lenses. 18.30 Section 18.30 Mineral... § 18.30 Windows and lenses. (a) MSHA may waive testing of materials for windows or lenses except headlight lenses. When tested, material for windows or lenses shall meet the test requirements prescribed...

  7. 30 CFR 18.30 - Windows and lenses.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Windows and lenses. 18.30 Section 18.30 Mineral... § 18.30 Windows and lenses. (a) MSHA may waive testing of materials for windows or lenses except headlight lenses. When tested, material for windows or lenses shall meet the test requirements prescribed...

  8. 30 CFR 18.30 - Windows and lenses.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Windows and lenses. 18.30 Section 18.30 Mineral... § 18.30 Windows and lenses. (a) MSHA may waive testing of materials for windows or lenses except headlight lenses. When tested, material for windows or lenses shall meet the test requirements prescribed...

  9. Avalanche and bit independence characteristics of double random phase encoding in the Fourier and Fresnel domains.

    PubMed

    Moon, Inkyu; Yi, Faliu; Lee, Yeon H; Javidi, Bahram

    2014-05-01

    In this work, we evaluate the avalanche effect and bit independence properties of the double random phase encoding (DRPE) algorithm in the Fourier and Fresnel domains. Experimental results show that DRPE has excellent bit independence characteristics in both the Fourier and Fresnel domains. However, DRPE achieves better avalanche effect results in the Fresnel domain than in the Fourier domain. DRPE gives especially poor avalanche effect results in the Fourier domain when only one bit is changed in the plaintext or in the encryption key. Despite this, DRPE shows satisfactory avalanche effect results in the Fresnel domain when any other number of bits changes in the plaintext or in the encryption key. To the best of our knowledge, this is the first report on the avalanche effect and bit independence behaviors of optical encryption approaches for bit units.

  10. Graphical Approach to Fresnel's Equations for Reflection and Refraction of Light.

    ERIC Educational Resources Information Center

    Doyle, William T.

    1980-01-01

    Develops a coordinate-free approach to Fresnel's equations for the reflection and refraction of light at a plane interface. Describes a graphical construction for finding the vector amplitudes of the reflected and transmitted waves. (Author/CS)

  11. Design of Fresnel Lens-Type Multi-Trapping Acoustic Tweezers

    PubMed Central

    Tu, You-Lin; Chen, Shih-Jui; Hwang, Yean-Ren

    2016-01-01

    In this paper, acoustic tweezers which use beam forming performed by a Fresnel zone plate are proposed. The performance has been demonstrated by finite element analysis, including the acoustic intensity, acoustic pressure, acoustic potential energy, gradient force, and particle distribution. The acoustic tweezers use an ultrasound beam produced by a lead zirconate titanate (PZT) transducer operating at 2.4 MHz and 100 Vpeak-to-peak in a water medium. The design of the Fresnel lens (zone plate) is based on air reflection, acoustic impedance matching, and the Fresnel half-wave band (FHWB) theory. This acoustic Fresnel lens can produce gradient force and acoustic potential wells that allow the capture and manipulation of single particles or clusters of particles. Simulation results strongly indicate a good trapping ability, for particles under 150 µm in diameter, in the minimum energy location. This can be useful for cell or microorganism manipulation. PMID:27886050

  12. Design of Fresnel Lens-Type Multi-Trapping Acoustic Tweezers.

    PubMed

    Tu, You-Lin; Chen, Shih-Jui; Hwang, Yean-Ren

    2016-11-23

    In this paper, acoustic tweezers which use beam forming performed by a Fresnel zone plate are proposed. The performance has been demonstrated by finite element analysis, including the acoustic intensity, acoustic pressure, acoustic potential energy, gradient force, and particle distribution. The acoustic tweezers use an ultrasound beam produced by a lead zirconate titanate (PZT) transducer operating at 2.4 MHz and 100 Vpeak-to-peak in a water medium. The design of the Fresnel lens (zone plate) is based on air reflection, acoustic impedance matching, and the Fresnel half-wave band (FHWB) theory. This acoustic Fresnel lens can produce gradient force and acoustic potential wells that allow the capture and manipulation of single particles or clusters of particles. Simulation results strongly indicate a good trapping ability, for particles under 150 µm in diameter, in the minimum energy location. This can be useful for cell or microorganism manipulation.

  13. Metal slit array Fresnel lens for wavelength-scale optical coupling to nanophotonic waveguides.

    PubMed

    Jung, Young Jin; Park, Dongwon; Koo, Sukmo; Yu, Sunkyu; Park, Namkyoo

    2009-10-12

    We propose a novel metal slit array Fresnel lens for wavelength-scale optical coupling into a nanophotonic waveguide. Using the plasmonic waveguide structure in Fresnel lens form, a much wider beam acceptance angle and wavelength-scale working distance of the lens was realized compared to a conventional dielectric Fresnel lens. By applying the plasmon waveguide dispersion relation to a phased antenna array model, we also develop and analyze design rules and parameters for the suggested metal slit Fresnel lens. Numerical assessment of the suggested structure shows excellent coupling efficiency (up to 59%) of the 10 mum free-space Gaussian beam to the 0.36 mum Si waveguide within a working distance of a few mum.

  14. Gravitational lenses and dark matter - Theory

    NASA Technical Reports Server (NTRS)

    Gott, J. Richard, III

    1987-01-01

    Theoretical models are presented for guiding the application of gravitational lenses to probe the characteristics of dark matter in the universe. Analytical techniques are defined for quantifying the mass associated with lensing galaxies (in terms of the image separation), determining the quantity of dark mass of the lensing bodies, and estimating the mass density of the lenses. The possibility that heavy halos are made of low mass stars is considered, along with the swallowing of central images of black holes or cusps in galactic nuclei and the effects produced on a lensed quasar image by nonbaryonic halos. The observable effects of dense groups and clusters and the characteristics of dark matter strings are discussed, and various types of images which are possible due to lensing phenomena and position are described.

  15. A rapid two-photon fabrication of tube array using an annular Fresnel lens.

    PubMed

    Zhang, Chenchu; Hu, Yanlei; Li, Jiawen; Li, Guoqiang; Chu, Jiaru; Huang, Wenhao

    2014-02-24

    A rapid method of fabricating microscopic tubular structures via two-photon polymerization is presented. Novel Fresnel lens is designed and applied to modulate the light field into a uniform ring pattern with controllable diameters. Comparing with the conventional holographic processing method, Fresnel lens shows higher uniformity and better flexibility, while easier to generate. This versatile method provides a powerful solution to produce tube structure array within several seconds.

  16. Scale-model experiments of applying a Fresnel prism to greenhouse covering

    SciTech Connect

    Kurata, Kenji )

    1991-01-01

    Effects of applying a Fresnel prism to a south roof of an EW-oriented single-span greenhouse were studied using scale models and artificial light as well as under a natural light condition. The experiments confirmed the theoretical predictions that the application of a Fresnel prism increases the light transmissivity in winter and decreases it in summer. The experiments also revealed, however, large spatial variations of the light transmissivity in the greenhouse.

  17. Performance analysis of a third-generation linear fresnel lens passively cooled photovoltaic collector

    SciTech Connect

    Mc Danal, A.J.; O'Neill, M.J.; Waller, K.A.

    1983-06-01

    The results of a parametric investigation in which the linear Fresnel lens concept has been optimized specifically for photovoltaic applications are presented. The results of the study show that performance improvements of about 14% can be achieved for the new generation of linear Fresnel lens passively cooled photovoltaic collectors using currently available lens and cell technology. The new design is presented and compared with the current baseline collector design.

  18. Electrically controllable Fresnel lens in 90° twisted nematic liquid crystals.

    PubMed

    Kuo, Chie-Tong; Li, Chien-Yu; Lin, Shih-Hung; Yeh, Hui-Chen

    2015-10-05

    This study presents a theoretical analysis and experimental demonstration of an electrically controllable Fresnel lens in a 90° twisted nematic liquid crystal cell. The cell gap was chosen to satisfy the Gooch-Tarry conditions, and therefore, the polarization rotation effect was valid regardless of the incident polarization direction. The polarization sensitivity of the diffraction efficiency of the 90° twisted nematic Fresnel lens was dependent on the applied voltage regime. Theoretical calculations effectively explain the experimental results.

  19. Fresnel diffraction effects in the frontlight for a liquid-crystal display.

    PubMed

    de Pooter, Jacco A; Cornelissen, Hugo J; Braat, Joseph J M

    2002-09-01

    In a new type of illumination system for reflective liquid-crystal displays, the frontlight, unwanted shadows appear in certain viewing directions. It will be shown that for an accurate description of these shadows the geometrical optics approach is not satisfactory and that Fresnel diffraction has to be taken into account. A model for the diffraction effects was developed, and the predicted results correspond well to the measurements. In addition, some remarkable effects were explained from the theory of Fresnel zones.

  20. Fundamental structure of Fresnel diffraction: natural sampling grid and the fractional Fourier transform.

    PubMed

    Ozaktas, Haldun M; Arık, Sercan Ö; Coşkun, Türker

    2011-07-01

    Fresnel integrals corresponding to different distances can be interpreted as scaled fractional Fourier transformations observed on spherical reference surfaces. We show that by judiciously choosing sample points on these curved reference surfaces, it is possible to represent the diffracted signals in a nonredundant manner. The change in sample spacing with distance reflects the structure of Fresnel diffraction. This sampling grid also provides a simple and robust basis for accurate and efficient computation, which naturally handles the challenges of sampling chirplike kernels.

  1. Fabrication of micro-lenses using excimer laser ablation by means of laser-generated grey-tone-masks

    NASA Astrophysics Data System (ADS)

    Klotzbuecher, T.; Dadic, D.

    2010-02-01

    Micro-lenses, including Fresnel-Lenses, were fabricated by excimer laser ablation of polymers by means of lasergenerated grey-tone-masks. The smallest reproducible holes that could be fabricated by excimer laser ablation (193 nm, 1 J/cm2) of chromium-on-quartz (thickness 50-100 nm) were around 3 μm, the pitch of which should be at least at the same value to ensure a reproducibility of hole-arrays. To achieve acceptable ablation times during the fabrication of the grey-tone-masks, on-the-fly ablation instead of step-and-repeat technique was used, operating the laser at a constant pulse repetition rate <30 Hz with a continuously moving quartz-substrate. In this way and using different encoding techniques it was possible to generate at least 11 different grey-tones. The available grey-tones were used to generate grey-tone-masks for ablation of Polymethylmethacrylate (PMMA) and Polycarbonate (PC). For that, fluences in the range of 0.07-0.14 J/cm2 could be applied, corresponding to a value of 1.25 J/cm2 on the workpiece without grey-tonemask and a value lying well below the damage threshold of the chromium mask. Refractive micro-lenses fabricated in this way did not show a good imaging quality, since 11 grey-tones is less than required to generate a continuous surface profile over the full diameter of the lens during ablation and the achievable aspect ratio is limited with the small fluences. However, flat diffractive micro-lenses of the Fresenel type with a quasi-continuously surface profile could be fabricated in a sufficient manner. This can be attributed to the fact that each segment of the Fresenel-lenses can be encoded by 11 grey-tones, leading to much smoother surface reliefs and to a sufficient imaging quality.

  2. Aberrations of sphero-cylindrical ophthalmic lenses.

    PubMed

    Malacara, Z; Malacara, D

    1990-04-01

    The authors have presented in two previous articles the graphic solutions resembling Tscherning ellipses, for spherical as well as for aspherical ophthalmic lenses free of astigmatism or power error. These solutions were exact, inasmuch as they were based on exact ray tracing, and not third-order theory as frequently done. In this paper sphero-cylindrical lenses are now analyzed, also using exact ray tracing. The functional dependence of the astigmatism and the power error for these lenses is described extensively.

  3. Design and simulation of imaging algorithm for Fresnel telescopy imaging system

    NASA Astrophysics Data System (ADS)

    Lv, Xiao-yu; Liu, Li-ren; Yan, Ai-min; Sun, Jian-feng; Dai, En-wen; Li, Bing

    2011-06-01

    Fresnel telescopy (short for Fresnel telescopy full-aperture synthesized imaging ladar) is a new high resolution active laser imaging technique. This technique is a variant of Fourier telescopy and optical scanning holography, which uses Fresnel zone plates to scan target. Compare with synthetic aperture imaging ladar(SAIL), Fresnel telescopy avoids problem of time synchronization and space synchronization, which decreasing technical difficulty. In one-dimensional (1D) scanning operational mode for moving target, after time-to-space transformation, spatial distribution of sampling data is non-uniform because of the relative motion between target and scanning beam. However, as we use fast Fourier transform (FFT) in the following imaging algorithm of matched filtering, distribution of data should be regular and uniform. We use resampling interpolation to transform the data into two-dimensional (2D) uniform distribution, and accuracy of resampling interpolation process mainly affects the reconstruction results. Imaging algorithms with different resampling interpolation algorithms have been analysis and computer simulation are also given. We get good reconstruction results of the target, which proves that the designed imaging algorithm for Fresnel telescopy imaging system is effective. This work is found to have substantial practical value and offers significant benefit for high resolution imaging system of Fresnel telescopy laser imaging ladar.

  4. The Alvarez and Lohmann refractive lenses revisited.

    PubMed

    Barbero, Sergio

    2009-05-25

    Alvarez and Lohmann lenses are variable focus optical devices based on lateral shifts of two lenses with cubic-type surfaces. I analyzed the optical performance of these types of lenses computing the first order optical properties (applying wavefront refraction and propagation) without the restriction of the thin lens approximation, and the spot diagram using a ray tracing algorithm. I proposed an analytic and numerical method to select the most optimum coefficients and the specific configuration of these lenses. The results show that Lohmann composite lens is slightly superior to Alvarez one because the overall thickness and optical aberrations are smaller.

  5. Ion exchange tempering of glass ophthalmic lenses.

    PubMed

    Keeney, A H; Duerson, H L

    1975-08-01

    We performed low velocity drop-ball tests using 5/8-, 7/8-, and 1-inch diameter steel balls on ophthalmic crown glass lenses chemically tempered by the ion exchange process. Four representative dioptric strengths (+ 2.50 spherical, - 2.50 spherical, -2.50 cylindrical, and plano) were studied with the isolated lenses mounted, convex side up, on the American National Standards Institute Z80 test block. New ion exchange lenses exhibited a 100 to 350% greater capacity for attenuation of energy from low velocity, large size missiles than matched lenses of similar strength prepared by the conventional heat-treating and air-quenching process.

  6. Light-Weight Radioisotope Heater Unit Safety Analysis Report (LWRHU-SAR). Volume I. A. Introduction and executive summary. B. Reference Design Document (RDD)

    SciTech Connect

    Johnson, E.W.

    1985-10-01

    The orbiter and probe portions of the NASA Galileo spacecraft contain components which require auxiliary heat during the mission. To meet these needs, the Department of Energy's (DOE's) Office of Special Nuclear Projects (OSNP) has sponsored the design, fabrication, and testing of a one-watt encapsulated plutonium dioxide-fueled thermal heater named the Light-Weight Radioisotope Heater Unit (LWRHU). This report addresses the radiological risks which might be encountered by people both at the launch area and worldwide should postulate mission failures or malfunctions occur, which would result in the release of the LWRHUs to the environment. Included are data from the design, mission descriptions, postulated accidents with their consequences, test data, and the derived source terms and personnel exposures for the various events.

  7. Light-Weight Radioisotope Heater Unit final safety analysis report (LWRHU-FSAR): Volume 1: A. Introduction and executive summary: B. Reference Design Document (RDD)

    SciTech Connect

    Johnson, E.W.

    1988-10-01

    The orbiter and probe portions of the National Aeronautics and Space Administration (NASA) Galileo spacecraft contain components which require auxiliary heat during the mission. To meet these needs, the Department of Energy's (DOE's) Office of Special Applications (OSA) has sponsored the design, fabrication, and testing of a one-watt encapsulated plutonium dioxide-fueled thermal heater named the Light-Weight Radioisotope Heater Unit (LWRHU). This report, prepared by Monsanto Research Corporation (MRC), addresses the radiological risks which might be encountered by people both at the launch area and worldwide should postulated mission failures or malfunctions occur, resulting in the release of the LWRHUs to the environment. Included are data from the design, mission descriptions, postulated accidents with their consequences, test data, and the derived source terms and personnel exposures for the various events. 11 refs., 44 figs., 11 tabs.

  8. Optically controllable and focus-tunable Fresnel lens in azo-dye-doped liquid crystals using a Sagnac interferometer.

    PubMed

    Yeh, Hui-Chen; Kuo, Yi-Chieh; Lin, Shih-Hung; Lin, Jia-De; Mo, Ting-Shan; Huang, Shuan-Yu

    2011-04-15

    This study demonstrates a tunable Fresnel lens in an azo-dye-doped liquid crystal (ADDLC) film using an interference technique. One Fresnel-patterned green beam using a Sagnac interferometer irradiated the UV-illuminated ADDLC cell, yielding a concentric zone plate distribution with homeotropic and isotropic structures in bright and dark regions of the green interference pattern. The proposed Fresnel lens is polarization independent, focus tunable, and the focusing efficiency of the device can be optically controlled.

  9. Gravitational Lensing Extends SETI Range

    NASA Astrophysics Data System (ADS)

    Factor, Richard

    Microwave SETI (The Search for Extraterrestrial Intelligence) focuses on two primary strategies, the "Targeted Search" and the "All-Sky Survey." Although the goal of both strategies is the unequivocal discovery of a signal transmitted by intelligent species outside our solar system, they pursue the strategies in very different manners and have vastly different requirements. This chapter introduces Gravitational Lensing SETI (GL-SETI), a third strategy. Its goal is the unequivocal discovery of an extraterrestrial signal, with equipment and data processing requirements that are substantially different from the commonly-used strategies. This strategy is particularly suitable for use with smaller radio telescopes and has budgetary requirements suitable for individual researchers.

  10. Offset lenses add versatility to phototypesetting machine

    NASA Technical Reports Server (NTRS)

    James, A. M.

    1966-01-01

    Offset lenses facilitate the composition of inputs of other than straight baseline characters on the Photon phototypesetting machine. A number of lenses in the turret are mounted in an offset pattern that causes characters projected through them to fall on the photographic paper in the magazine above and below the baseline.

  11. BAYESIAN INFERENCE OF CMB GRAVITATIONAL LENSING

    SciTech Connect

    Anderes, Ethan; Wandelt, Benjamin D.; Lavaux, Guilhem

    2015-08-01

    The Planck satellite, along with several ground-based telescopes, has mapped the cosmic microwave background (CMB) at sufficient resolution and signal-to-noise so as to allow a detection of the subtle distortions due to the gravitational influence of the intervening matter distribution. A natural modeling approach is to write a Bayesian hierarchical model for the lensed CMB in terms of the unlensed CMB and the lensing potential. So far there has been no feasible algorithm for inferring the posterior distribution of the lensing potential from the lensed CMB map. We propose a solution that allows efficient Markov Chain Monte Carlo sampling from the joint posterior of the lensing potential and the unlensed CMB map using the Hamiltonian Monte Carlo technique. The main conceptual step in the solution is a re-parameterization of CMB lensing in terms of the lensed CMB and the “inverse lensing” potential. We demonstrate a fast implementation on simulated data, including noise and a sky cut, that uses a further acceleration based on a very mild approximation of the inverse lensing potential. We find that the resulting Markov Chain has short correlation lengths and excellent convergence properties, making it promising for applications to high-resolution CMB data sets in the future.

  12. Lenses and Perception: Investigations with Light

    ERIC Educational Resources Information Center

    Akcay, Hakan

    2005-01-01

    The main goals of these activities are to help students learn how a convex lens can serve as a magnifying lens and how light travels and creates images. These explorations will introduce middle school students to different types of lenses and how they work. Students will observe and describe how lenses bend light that passes through them and how…

  13. Phakic Intraocular Lenses and their Special Indications

    PubMed Central

    Pineda, Roberto; Chauhan, Tulika

    2016-01-01

    Phakic intraocular lenses revolutionize refractive surgery and continue to serve as an excellent option for vision correction in patients who are not ideal candidates for laser vision correction. This article will review special indications of phakic intraocular lenses in the clinical practice. PMID:27994811

  14. An Algorithm for Evaluating Fresnel-Zone Textural Roughness for Seismic Facies Interpretation

    NASA Astrophysics Data System (ADS)

    Di, H.; Gao, D.

    2014-12-01

    In reflection seismic interpretation, a 1-D convolutional model is commonly used to interpret amplitude variations based on the geometric ray theory assuming seismic wave to reflect at a reflection point; however, the propagation of seismic waves actually occurs in a finite zone around the geometric ray path and gets reflected from a zone known as Fresnel zone. The collected signal at the surface turns out to be the superposition of reflections from within the Fresnel zone, which is a function of texture. Generally, for a rough texture such as sandstone, the dominant reflection is from the zone margin, while for a smooth texture such as marine shale, the dominant reflection is from the zone center. Based on this concept, Fresnel-zone texture directly affects amplitude variations with offset (AVO), azimuth (AVAZ), and frequency (AVF). Here we develop a computer algorithm for evaluating Fresnel-zone textural roughness. The algorithm starts with dividing the Fresnel zone into a set of micro-zones. It then builds an initial texture model to be convolved with an extracted wavelet. By comparing the synthetic signal from a Fresnel zone to the real seismic signal within an analysis window at a target location, the model is adjusted and updated until both synthetic and real signals match best. The roughness is evaluated as the correlation coefficient between the generated texture model within the Fresnel zone and the ideal model for a rough texture medium. Our new algorithm is applied to a deep-water 3D seismic volume over offshore Angola, west Africa. The results show that a rough texture is associated with channel sands, whereas a smooth texture with marine shale.

  15. Fresnel equations and transmission line analogues for diffraction gratings

    SciTech Connect

    Kaushik, S.

    1995-08-01

    A simple and intuitive formalism is presented to describe diffraction in multi-layered periodic structures. We use the well known results from scalar analysis (wave propagation in homogeneous layered media) and show that they can be generalized rather readily to vector problems such as diffraction analysis. Specifically, we derive: (1) generalized Fresnel equations appropriate for reflection and transmission from an infinitely thick grating, (2) a generalized Airy formula for thin-film to describe reflection and transmission of light through a lamellar grating and (3) a matrix propagation method akin to that used for multi-layer thin film analysis. The results developed here complement the recent work on R-matrix and S-matrix propagation algorithms that have been used in connection with modal and differential grating theories. These algorithms have proven to be numerically stable for calculating diffraction efficiencies from deep groove gratings. The formalism developed here expands upon the earlier literature by providing important details that are hitherto unavailable.

  16. Fresnel incoherent correlation holography and its imaging properties

    NASA Astrophysics Data System (ADS)

    Wang, Zhipeng; Ma, Haotong; Ren, Ge; Xie, Zongliang; Yu, Huan

    2016-09-01

    The incoherent digital holography makes it possible to record holograms under incoherent illumination, which lowers requirement for the coherence of light sources and results in expanding its application to white-light and fluorescence illuminating circumstances. The Fresnel Incoherent Correlation Holography (FINCH) technology achieves diverging the incident beam and shifting phase by mounting phase masks on the phase modulator. Then it obtains holograms with phase difference and reconstructs the image. In this paper, we explain the principles of the FINCH technology, and introduce the n-step phase-shifting method which is utilized to eliminate the twin image and bias term in holograms. During the research, we studied what impact the term n may have on imaging performance, compared imaging performances when different phase masks are mounted on SLM, and established simulation system on imaging with which imaging performances are deeply inspected. At last, it is shown in the research that the FINCH technology could record holograms of objects, from which clear images could be reconstructed digitally.

  17. Design and analysis of a folded Fresnel Zone Plate antenna

    NASA Astrophysics Data System (ADS)

    Ji, Yu; Fujita, Masaharu

    1994-08-01

    Based on the Kirchhoff-Huygens diffraction theory, a simple analytical method of a planar folded Fresnel zone-plate (FZP), that is the case when a planar reflector is placed behind the zone plates, has been developed. According to the numerical calculation results, the design procedure of the FZP antenna has been presented, and its focusing characteristics and gain-optimized conditions have been discussed. The variations of the focal field distribution with the antenna parameters such as zone numbers, focal length and antenna diameter and the radiation power patterns of the FZP have been simulated numerically. To take a good balance of both receiving and transmitting antennas, at 60GHz operating frequency, the focal length should be designed as a half of the antenna diameter and the zone number should be from 10 to 15. The results in this work show that the folded FZP has good focal characteristics and off-axis performance, and its antenna gain can be optimized by the suitable antenna parameter design. The possibility of applying the folded FZP as a low cost and high gain antenna without strict manufacturing requirement for millimeter-wave communications has been shown.

  18. An Electron-Beam Profile Monitor Using Fresnel Zone Plates

    SciTech Connect

    Nakamura, Norio; Sakai, Hiroshi; Iida, Kensuke; Shinoe, Kenji; Takaki, Hiroyuki; Fujisawa, Masami; Hayano, Hitoshi; Muto, Toshiya; Nomura, Masaharu; Kamiya, Yukihide; Koseki, Tadashi; Amemiya, Yoshiyuki; Aoki, Nobutada; Nakayama, Koichi

    2004-05-12

    We have developed a beam profile monitor using two Fresnel zone plates (FZPs) at the KEK-ATF (Accelerator Test Facility) damping ring to measure small electron-beam sizes for low-emittance synchrotron radiation sources. The monitor has a structure of an X-ray microscope, where two FZPs constitute an X-ray imaging optics. In the monitor system, the synchrotron radiation from the electron beam at the bending magnet is monochromatized to 3.235-keV X-rays by a crystal monochromator and the transverse electron-beam image is twenty-times magnified by the two FZPs and detected on an X-ray CCD camera. This monitor has the following advantages: (1) high spatial resolution, (2) non-destructive measurement, (3) real-time monitoring, and (4) direct electron-beam imaging. With the beam profile monitor, we have succeeded in obtaining a clear electron-beam image and measuring the extremely small beam size less than 10 {mu}m. The measured magnification of the imaging optics was in good agreement with the design value.

  19. High precision refractometry based on Fresnel diffraction from phase plates.

    PubMed

    Tavassoly, M Taghi; Naraghi, Roxana Rezvani; Nahal, Arashmid; Hassani, Khosrow

    2012-05-01

    When a transparent plane-parallel plate is illuminated at a boundary region by a monochromatic parallel beam of light, Fresnel diffraction occurs because of the abrupt change in phase imposed by the finite change in refractive index at the plate boundary. The visibility of the diffraction fringes varies periodically with changes in incident angle. The visibility period depends on the plate thickness and the refractive indices of the plate and the surrounding medium. Plotting the phase change versus incident angle or counting the visibility repetition in an incident-angle interval provides, for a given plate thickness, the refractive index of the plate very accurately. It is shown here that the refractive index of a plate can be determined without knowing the plate thickness. Therefore, the technique can be utilized for measuring plate thickness with high precision. In addition, by installing a plate with known refractive index in a rectangular cell filled with a liquid and following the described procedures, the refractive index of the liquid is obtained. The technique is applied to measure the refractive indices of a glass slide, distilled water, and ethanol. The potential and merits of the technique are also discussed.

  20. Weak gravitational lensing theory and data analysis

    NASA Astrophysics Data System (ADS)

    Hirata, Christopher Michael

    2005-12-01

    This thesis describes methodology for analysis of weak gravitational lensing data. Weak lensing, i.e. the perturbative distortion of the images of distant objects by the gravitational deflection of light, is an important tool for understanding the distribution of matter in the universe. This is interesting because a number of extentions to the standard cosmological model, including dynamical dark energy and neutrino masses, affect the growth of structure and hence may be detectable using weak lensing. Studies of weak lensing are also motivated by lensing's ability to affect the modes in the cosmic microwave background (CMB) polarization that are sensitive to primordial gravitational waves. Both lensing of galaxies and lensing of the CMB are considered here. The section devoted to galaxies is principally concerned with measuring the lensing-induced shape distortions from galaxy images in the Sloan Digital Sky Survey (SDSS), although the methodology will be applicable to future projects. We investigate in detail the problem of separating lensing from other shape distortions such as those induced by the atmosphere, the telescope, and photon Poisson noise. Since the intrinsic shapes of observed galaxies are not known, weak lensing observations always attempt some sort of statistical averaging over galaxies that presumably have independent orientations. We investigate the extent to which this process "averages down" the intrinsic shapes and identify a new type of bias that can affect the weak lensing power spectrum. Selection biases are considered and their importance in SDSS estimated. We present some recent cosmological results using the SDSS analysis, including new upper limits on the neutrino mass. Lensing of the CMB has not yet been detected, nevertheless several experiments are being built that should have the sensitivity to see it. The statistical problem of extracting lensing information from the distortion of the CMB anisotropy is considered, and in the case of

  1. [Use of rigid gas permeable contact lenses].

    PubMed

    Habela, M

    1992-01-01

    By application of contact lenses destined for a extended wearing, for preservation of a normal structure and metabolism of the cornea a considerable permeability of the contact lens for oxygen is necessary (Dk/L 75-80). The actually most popular in the world soft contact lenses have no such parameters. The application of rigid lenses produced from materials of high permeability for oxygen enables the extended wearing without substantial disturbances of the corneal metabolism. The paper presents a new generation of fluoro-silicone acrylates used for the production of contact lenses permeable for oxygen. Discussed are the problems connected with the adjusting of these lenses, their tolerance and influence on the corneal metabolism.

  2. The Search for Lensed Supernovae

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2017-01-01

    Type Ia supernovae that have multiple images due to gravitational lensing can provide us with a wealth of information both about the supernovae themselves and about our surrounding universe. But how can we find these rare explosions?Clues from Multiple ImagesWhen light from a distant object passes by a massive foreground galaxy, the galaxys strong gravitational pull can bend the light, distorting our view of the backgroundobject. In severe cases, this process can cause multiple images of the distant object to appear in the foreground lensing galaxy.An illustration of gravitational lensing. Light from the distant supernova is bent as it passes through a giant elliptical galaxy in the foreground, causing multiple images of the supernova to appear to be hosted by the elliptical galaxy. [Adapted from image by NASA/ESA/A. Feild (STScI)]Observations of multiply-imaged Type Ia supernovae (explosions that occur when white dwarfs in binary systems exceed their maximum allowed mass) could answer a number of astronomical questions. Because Type Ia supernovae are standard candles, distant, lensed Type Ia supernovae can be used to extend the Hubble diagram to high redshifts. Furthermore, the lensing time delays from the multiply-imaged explosion can provide high-precision constraints on cosmological parameters.The catch? So far, weve only found one multiply-imaged Type Ia supernova: iPTF16geu, discovered late last year. Were going to need a lot more of them to develop a useful sample! So how do we identify themutiply-imaged Type Ias among the many billions of fleeting events discovered in current and future surveys of transients?Searching for AnomaliesAbsolute magnitudes for Type Ia supernovae in elliptical galaxies. None are expected to be above -20 in the B band, so if we calculate a magnitude for a Type Ia supernova thats larger than this, its probably not hosted by the galaxy we think it is! [Goldstein Nugent 2017]Two scientists from University of California, Berkeley and

  3. Planck 2015 results. XV. Gravitational lensing

    NASA Astrophysics Data System (ADS)

    Planck Collaboration; Ade, P. A. R.; Aghanim, N.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A. J.; Barreiro, R. B.; Bartlett, J. G.; Bartolo, N.; Basak, S.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bock, J. J.; Bonaldi, A.; Bonavera, L.; Bond, J. R.; Borrill, J.; Bouchet, F. R.; Boulanger, F.; Bucher, M.; Burigana, C.; Butler, R. C.; Calabrese, E.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chiang, H. C.; Christensen, P. R.; Church, S.; Clements, D. L.; Colombi, S.; Colombo, L. P. L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B. P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R. D.; Davis, R. J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Diego, J. M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dunkley, J.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T. A.; Eriksen, H. K.; Fergusson, J.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A. A.; Franceschi, E.; Frejsel, A.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K. M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J. E.; Hansen, F. K.; Hanson, D.; Harrison, D. L.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S. R.; Hivon, E.; Hobson, M.; Holmes, W. A.; Hornstrup, A.; Hovest, W.; Huffenberger, K. M.; Hurier, G.; Jaffe, A. H.; Jaffe, T. R.; Jones, W. C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T. S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C. R.; Leonardi, R.; Lesgourgues, J.; Levrier, F.; Lewis, A.; Liguori, M.; Lilje, P. B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P. M.; Macías-Pérez, J. F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Martin, P. G.; Martínez-González, E.; Masi, S.; Matarrese, S.; McGehee, P.; Meinhold, P. R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Murphy, J. A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C. B.; Nørgaard-Nielsen, H. U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C. A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Popa, L.; Pratt, G. W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J. P.; Reach, W. T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rowan-Robinson, M.; Rubiño-Martín, J. A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Seiffert, M. D.; Shellard, E. P. S.; Spencer, L. D.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J. A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L. A.; Wandelt, B. D.; Wehus, I. K.; White, M.; Yvon, D.; Zacchei, A.; Zonca, A.

    2016-09-01

    We present the most significant measurement of the cosmic microwave background (CMB) lensing potential to date (at a level of 40σ), using temperature and polarization data from the Planck 2015 full-mission release. Using a polarization-only estimator, we detect lensing at a significance of 5σ. We cross-check the accuracy of our measurement using the wide frequency coverage and complementarity of the temperature and polarization measurements. Public products based on this measurement include an estimate of the lensing potential over approximately 70% of the sky, an estimate of the lensing potential power spectrum in bandpowers for the multipole range 40 ≤ L ≤ 400, and an associated likelihood for cosmological parameter constraints. We find good agreement between our measurement of the lensing potential power spectrum and that found in the ΛCDM model that best fits the Planck temperature and polarization power spectra. Using the lensing likelihood alone we obtain a percent-level measurement of the parameter combination σ8Ω0.25m = 0.591 ± 0.021. We combine our determination of the lensing potential with the E-mode polarization, also measured by Planck, to generate an estimate of the lensing B-mode. We show that this lensing B-mode estimate is correlated with the B-modes observed directly by Planck at the expected level and with a statistical significance of 10σ, confirming Planck's sensitivity to this known sky signal. We also correlate our lensing potential estimate with the large-scale temperature anisotropies, detecting a cross-correlation at the 3σ level, as expected because of dark energy in the concordance ΛCDM model.

  4. Not only Gravitational Lensing, but in general Medium Lensing

    NASA Astrophysics Data System (ADS)

    Smarandache, Florentin

    2013-05-01

    According to the General Theory of Relativity the gravity curves the spacetime and everything over there follows a curved path. The space being curved near massive cosmic bodies is just a metaphor, not a fact. We dough that gravity is only geometry. The deflection of light (Gravitational Lensing) near massive cosmic bodies is not due because of a ``curved space'', but because of the medium composition (medium that could be formed by waves, particles, plasma, dust, gaseous, fluids, solids, etc.), to the medium density, medium heterogeneity, and to the electromagnetic and gravitational fields contained in that medium that light passes through. This medium deviates the light direction, because of the interactions of photons with other particles. The space is not empty; it has various nebulae and fields and corpuscles, etc. Light bends not only because of the gravity but also because of the medium gradient and refraction index, similarly as light bends when it leaves or enters a liquid, a plastic, a glass, or a quartz. The inhomogeneous medium may act as an optical lens such that its refractive index varies in a fashion, alike the Gradient-Index Lens. We talk about a Medium Lensing, which means that photons interact with other particles in the medium. For example, the interaction between a photon of electromagnetic radiation with a charged particle (let's say with a free electron), which is known as Compton Effect, produces an increase in the photon's wavelength. In the Inverse Compton Effect the low-energy photons gain energy because they were scattered by much-higher energy free electrons.

  5. Realization of Fourier and Fresnel computer-generated holograpm based on MATLAB

    NASA Astrophysics Data System (ADS)

    Lin, GuoQiang; Ren, XueChang

    2016-10-01

    Computer-generated hologram(CGH) can encode the picture. The image, which equals the original object of traditional optics, can be divided into two parts. A portion of it encoding into Fourier computer generated hologram(CGH), while the remaining are coded into Fresnel computer generated hologram. So in the processing of information transmission, the possibility of being stolen details can be greatly reduced. When the image is coded into the Fourier CGH and Fresnel CGH and reached the receiving end, the original image should be obtained by the reconstruction of the two computer generated holograms. This article presents three important things. Firstly, it provides the recording and reconstruction - both of them consist of the holographic technique - of the source program of Fresnel CGH and Fourier CGH in MATLAB. MATLAB(Matrix Laboratory) is the abbreviation of Laboratory Matrix and commercial mathematical software produced by the United States company. Secondly, it isolates the original image and the conjugate image in regeneration of Fourier CGH by using all zero matrix. Even though the original image and the conjugate image can be separated, the two of them also prevent us to acquire the original message. For reserving the most important image, we should apply the window function to filter one of them. Finally, in the coding of Fourier CGH and Fresnel CGH, this passage describes several functions to decrease the noise of the original image which is encoded into program. The function can be available in Fourier CGH and Fresnel CGH.

  6. Large Space Telescopes Using Fresnel Lens for Power Beaming, Astronomy and Sail Missions

    SciTech Connect

    Early, J T

    2002-10-15

    The concept of using Fresnel optics as part of power beaming, astronomy or sail systems has been suggested by several authors. The primary issues for large Fresnel optics are the difficulties in fabricating these structures and deploying them in space and for astronomy missions the extremely narrow frequency range of these optics. In proposals where the telescope is used to transmit narrow frequency laser power, the narrow bandwidth has not been an issue. In applications where the optic is to be used as part of a telescope, only around 10{sup -5} to limited frequency response of a Fresnel optic is addressed by the use of a corrective optic that will broaden the frequency response of the telescope by three or four orders of magnitude. This broadening will dramatically increase the optical power capabilities of the system and will allow some spectroscopy studies over a limited range. Both the fabrication of Fresnel optics as large as five meters and the use of corrector optics for telescopes have been demonstrated at LLNL. For solar and laser sail missions the use of Fresnel amplitude zone plates made of very thin sail material is also discussed.

  7. Scanning Miniature Microscopes without Lenses

    NASA Technical Reports Server (NTRS)

    Wang, Yu

    2009-01-01

    The figure schematically depicts some alternative designs of proposed compact, lightweight optoelectronic microscopes that would contain no lenses and would generate magnified video images of specimens. Microscopes of this type were described previously in Miniature Microscope Without Lenses (NPO - 20218), NASA Tech Briefs, Vol. 22, No. 8 (August 1998), page 43 and Reflective Variants of Miniature Microscope Without Lenses (NPO 20610), NASA Tech Briefs, Vol. 26, No. 9 (September 1999), page 6a. To recapitulate: In the design and construction of a microscope of this type, the focusing optics of a conventional microscope are replaced by a combination of a microchannel filter and a charge-coupled-device (CCD) image detector. Elimination of focusing optics reduces the size and weight of the instrument and eliminates the need for the time-consuming focusing operation. The microscopes described in the cited prior articles contained two-dimensional CCDs registered with two-dimensional arrays of microchannels and, as such, were designed to produce full two-dimensional images, without need for scanning. The microscopes of the present proposal would contain one-dimensional (line image) CCDs registered with linear arrays of microchannels. In the operation of such a microscope, one would scan a specimen along a line perpendicular to the array axis (in other words, one would scan in pushbroom fashion). One could then synthesize a full two-dimensional image of the specimen from the line-image data acquired at one-pixel increments of position along the scan. In one of the proposed microscopes, a beam of unpolarized light for illuminating the specimen would enter from the side. This light would be reflected down onto the specimen by a nonpolarizing beam splitter attached to the microchannels at their lower ends. A portion of the light incident on the specimen would be reflected upward, through the beam splitter and along the microchannels, to form an image on the CCD. If the

  8. CONSTRAINING SOURCE REDSHIFT DISTRIBUTIONS WITH GRAVITATIONAL LENSING

    SciTech Connect

    Wittman, D.; Dawson, W. A.

    2012-09-10

    We introduce a new method for constraining the redshift distribution of a set of galaxies, using weak gravitational lensing shear. Instead of using observed shears and redshifts to constrain cosmological parameters, we ask how well the shears around clusters can constrain the redshifts, assuming fixed cosmological parameters. This provides a check on photometric redshifts, independent of source spectral energy distribution properties and therefore free of confounding factors such as misidentification of spectral breaks. We find that {approx}40 massive ({sigma}{sub v} = 1200 km s{sup -1}) cluster lenses are sufficient to determine the fraction of sources in each of six coarse redshift bins to {approx}11%, given weak (20%) priors on the masses of the highest-redshift lenses, tight (5%) priors on the masses of the lowest-redshift lenses, and only modest (20%-50%) priors on calibration and evolution effects. Additional massive lenses drive down uncertainties as N{sub lens}{sup -1/2}, but the improvement slows as one is forced to use lenses further down the mass function. Future large surveys contain enough clusters to reach 1% precision in the bin fractions if the tight lens-mass priors can be maintained for large samples of lenses. In practice this will be difficult to achieve, but the method may be valuable as a complement to other more precise methods because it is based on different physics and therefore has different systematic errors.

  9. Investigations of galaxy clusters using gravitational lensing

    NASA Astrophysics Data System (ADS)

    Wiesner, Matthew P.

    In this dissertation, we discuss the properties of galaxy clusters that have been determined using strong and weak gravitational lensing. A galaxy cluster is a collection of galaxies that are bound together by the force of gravity, while gravitational lensing is the bending of light by gravity. Strong lensing is the formation of arcs or rings of light surrounding clusters and weak lensing is a change in the apparent shapes of many galaxies. In this work we examine the properties of several samples of galaxy clusters using gravitational lensing. In Chapter 1 we introduce astrophysical theory of galaxy clusters and gravitational lensing. In Chapter 2 we examine evidence from our data that galaxy clusters are more concentrated than cosmology would predict. In Chapter 3 we investigate whether our assumptions about the number of galaxies in our clusters was valid by examining new data. In Chapter 4 we describe a determination of a relationship between mass and number of galaxies in a cluster at higher redshift than has been found before. In Chapter 5 we describe a model of the mass distribution in one of the ten lensing systems discovered by our group at Fermilab. Finally in Chapter 6 we summarize our conclusions.

  10. Investigations of Galaxy Clusters Using Gravitational Lensing

    SciTech Connect

    Wiesner, Matthew P.

    2014-08-01

    In this dissertation, we discuss the properties of galaxy clusters that have been determined using strong and weak gravitational lensing. A galaxy cluster is a collection of galaxies that are bound together by the force of gravity, while gravitational lensing is the bending of light by gravity. Strong lensing is the formation of arcs or rings of light surrounding clusters and weak lensing is a change in the apparent shapes of many galaxies. In this work we examine the properties of several samples of galaxy clusters using gravitational lensing. In Chapter 1 we introduce astrophysical theory of galaxy clusters and gravitational lensing. In Chapter 2 we examine evidence from our data that galaxy clusters are more concentrated than cosmology would predict. In Chapter 3 we investigate whether our assumptions about the number of galaxies in our clusters was valid by examining new data. In Chapter 4 we describe a determination of a relationship between mass and number of galaxies in a cluster at higher redshift than has been found before. In Chapter 5 we describe a model of the mass distribution in one of the ten lensing systems discovered by our group at Fermilab. Finally in Chapter 6 we summarize our conclusions.

  11. Adherence of Pseudomonas aeruginosa to contact lenses

    SciTech Connect

    Miller, M.J.

    1988-01-01

    The purpose of this research was to examined the interactions of P. aeruginosa with hydrogel contact lenses and other substrata, and characterize adherence to lenses under various physiological and physicochemical conditions. Isolates adhered to polystyrene, glass, and hydrogel lenses. With certain lens types, radiolabeled cells showed decreased adherence with increasing water content of the lenses, however, this correlation with not found for all lenses. Adherence to rigid gas permeable lenses was markedly greater than adherence to hydrogels. Best adherence occurred near pH 7 and at a sodium chloride concentration of 50 mM. Passive adhesion of heat-killed cells to hydrogels was lower than the adherence obtained of viable cells. Adherence to hydrogels was enhanced by mucin, lactoferrin, lysozyme, IgA, bovine serum albumin, and a mixture of these macromolecules. Adherence to coated and uncoated lenses was greater with a daily-wear hydrogel when compared with an extended-wear hydrogel of similar polymer composition. Greater adherence was attributed to a higher concentration of adsorbed macromolecules on the 45% water-content lens in comparison to the 55% water-content lens.

  12. Natural wormholes as gravitational lenses

    SciTech Connect

    Cramer, J.G.; Forward, R.L.; Morris, M.S.; Visser, M.; Benford, G.; Landis, G.A. Forward Unlimited, P.O. Box 2783, Malibu, California 90265 Department of Physics and Astronomy, Butler University, Indianapolis, Indiana 46208 Physics Department, Washington University, St. Louis, Missouri 63130-4899 Physics Department, University of California at Irvine, Irvine, California 92717-4575 NASA Lewis Research Center, Mail Code 302-1, Cleveland, Ohio 44135-3191 )

    1995-03-15

    Once quantum mechanical effects are included, the hypotheses underlying the positive mass theorem of classical general relativity fail. As an example of the peculiarities attendant upon this observation, a wormhole mouth embedded in a region of high mass density might accrete mass, giving the other mouth a net [ital negative] mass of unusual gravitational properties. The lensing of such a gravitationally negative anomalous compact halo object (GNACHO) will enhance background stars with a time profile that is observable and qualitatively different from that recently observed for massive compact halo objects (MACHO's) of positive mass. While the analysis is discussed in terms of wormholes, the observational test proposed is more generally a search for compact negative mass objects of any origin. We recommend that MACHO search data be analyzed for GNACHO's.

  13. [Correction of keratoconus with soft contact lenses].

    PubMed

    Koos, D; Bitea, M J

    1989-01-01

    The authors present their experience in using soft contact lenses in 33 eyes with keratoconus (18 patients). Adaptation was possible only when the doctor-patient collaboration was good. Visual acuity (VA) of 0.4-1 was obtained in 85% cases versus 42.5% when glasses were used. In the period under observation no case of VA decrease was recorded. The subjects tolerated well the contact lenses. The specialty literature contains data indicating not only the optical role of the contact lenses but also their therapeutic, tectorial role.

  14. Flexibility of hard gas permeable contact lenses.

    PubMed

    Stevenson, R W

    1988-11-01

    Gas permeable (GP) lenses can flex on some eyes producing unpredictable clinical results. A method of measuring the flexibility of hard GP materials has been developed and shown to be repeatable. Materials in the form of flats rather than lenses were used. Differences between materials were found and in general a linear relation was shown to exist between maximum flexing and quoted oxygen permeability (r = 0.78, p less than 0.05). It is recommended that flexibility be measured and reported in the data presented with all new GP polymers. The term "hard" rather than "rigid" in describing GP lenses is suggested.

  15. Tevatron Electron Lenses: Design and Operation

    SciTech Connect

    Shiltsev, Vladimir; Bishofberger, Kip; Kamerdzhiev, Vsevolod; Kozub, Sergei; Kufer, Matthew; Kuznetsov, Gennady; Martinez, Alexander; Olson, Marvin; Pfeffer, Howard; Saewert, Greg; Scarpine, Vic; /Fermilab /SLAC /Fermilab /Serpukhov, IHEP /Novosibirsk, IYF /Serpukhov, IHEP /Fermilab

    2008-08-01

    The beam-beam effects have been the dominating sources of beam loss and lifetime limitations in the Tevatron proton-antiproton collider [1]. Electron lenses were originally proposed for compensation of electromagnetic long-range and head-on beam-beam interactions of proton and antiproton beams [2]. Results of successful employment of two electron lenses built and installed in the Tevatron are reported in [3,4,5]. In this paper we present design features of the Tevatron electron lenses (TELs), discuss the generation of electron beams, describe different modes of operation and outline the technical parameters of various subsystems.

  16. Wettability and silicone hydrogel lenses: a review.

    PubMed

    Keir, Nancy; Jones, Lyndon

    2013-01-01

    One of the major breakthroughs in the development of silicone hydrogel contact lenses has related to the ability of manufacturers to overcome the surface hydrophobicity that occurred with silicone elastomer lenses. However, the wettability of silicone hydrogel lenses continues to be of interest as a potential link between in vivo lens performance and contact lens-related comfort. This article will review some of the knowledge we have gained in the area of contact lens wettability over the past decade and will discuss some of the challenges related to its measurement.

  17. Twin axial vortices generated by Fibonacci lenses.

    PubMed

    Calatayud, Arnau; Ferrando, Vicente; Remón, Laura; Furlan, Walter D; Monsoriu, Juan A

    2013-04-22

    Optical vortex beams, generated by Diffractive Optical Elements (DOEs), are capable of creating optical traps and other multi-functional micromanipulators for very specific tasks in the microscopic scale. Using the Fibonacci sequence, we have discovered a new family of DOEs that inherently behave as bifocal vortex lenses, and where the ratio of the two focal distances approaches the golden mean. The disctintive optical properties of these Fibonacci vortex lenses are experimentally demonstrated. We believe that the versatility and potential scalability of these lenses may allow for new applications in micro and nanophotonics.

  18. Fresnel zone antenna for dual-band detection at millimeter and infrared wavelengths.

    PubMed

    Alda, Javier; González, Francisco Javier

    2009-03-15

    In this work the concept of a Fresnel zone antenna for dual-band detection in the IR and millimeter wave region is presented. The design is based on a Fresnel zone plate lens in the IR that is transformed to serve as a millimeter-wave antenna. Two different designs are presented, a circular-zone design that gives a high diffractive efficiency in the IR and a square-zone design that gives a higher response in the millimeter band but a lower focusing efficiency in the IR. Both designs have an operation bandwidth with the same low frequency limit of 400 GHz (750 microm), which can be tailored by changing the number of Fresnel zones, and a high frequency limit of 4.5 THz (65 microm) for the circular-zone design and 5 THz (59 microm) for the square-zone design.

  19. Fresnel-region fields and antenna noise-temperature calculations for advanced microwave sounding units

    NASA Technical Reports Server (NTRS)

    Schmidt, R. F.

    1982-01-01

    A transition from the antenna noise temperature formulation for extended noise sources in the far-field or Fraunhofer-region of an antenna to one of the intermediate near field or Fresnel-region is discussed. The effort is directed toward microwave antenna simulations and high-speed digital computer analysis of radiometric sounding units used to obtain water vapor and temperature profiles of the atmosphere. Fresnel-region fields are compared at various distances from the aperture. The antenna noise temperature contribution of an annular noise source is computed in the Fresnel-region (D squared/16 lambda) for a 13.2 cm diameter offset-paraboloid aperture at 60 GHz. The time-average Poynting vector is used to effect the computation.

  20. Long-Life and High-Areal-Capacity Li-S Batteries Enabled by a Light-Weight Polar Host with Intrinsic Polysulfide Adsorption.

    PubMed

    Pang, Quan; Nazar, Linda F

    2016-04-26

    Lithium-sulfur batteries are attractive electrochemical energy storage systems due to their high theoretical energy density and very high natural abundance of sulfur. However, practically, Li-S batteries suffer from short cycling life and low sulfur utilization, particularly in the case of high-sulfur-loaded cathodes. Here, we report on a light-weight nanoporous graphitic carbon nitride (high-surface-area g-C3N4) that enables a sulfur electrode with an ultralow long-term capacity fade rate of 0.04% per cycle over 1500 cycles at a practical C/2 rate. More importantly, it exhibits good high-sulfur-loading areal capacity (up to 3.5 mAh cm(-2)) with stable cell performance. We demonstrate the strong chemical interaction of g-C3N4 with polysulfides using a combination of spectroscopic experimental studies and first-principles calculations. The 53.5% concentration of accessible pyridinic nitrogen polysulfide adsorption sites is shown to be key for the greatly improved cycling performance compared to that of N-doped carbons.