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Sample records for light-weight fresnel lenses

  1. 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.

  2. Subharmonic focal-length intensities formed by Fresnel lenses.

    PubMed

    Davis, J A; Field, A M; Cottrell, D M

    1994-12-10

    Binary Fresnel lenses produce focused spots at subharmonics of the principal focal length of the lens. The intensities of these focal spots can be controlled by variation of the relative widths of the rings of the Fresnel lens compared with the spacings between the rings. Theory is presented and experimentalverification is provided with Fresnel lenses written onto the magneto-optic spatial light modulator. PMID:20963052

  3. 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

  4. Telecentric large-field lenses using Fresnel optics

    NASA Astrophysics Data System (ADS)

    Schuster, Norbert; Schoenheit, Thomas

    2002-02-01

    The practical application of Fresnel lenses in imaging systems is very much disputed. However, in large field, object side, telecentric lenses, conditions are such that the advantages of lightness, cheap production, and short construction length dominate the disadvantages. These disadvantages concern the reduced image quality. Starting from any paraxial relations, we present analytic equations which are useful in estimating the changes in the aberration balance, when a well compensated glass lens front group is replaced by a Fresnel lens singlet. The comparison of a pair of telecentric lenses with the same basic parameters, built with a glass lens front group and with a Fresnel singlet front group, confirms these equations. The reduced image quality, using a Fresnel singlet as front group in an object side telecentric lens, is caused by noncompensated lateral chromatic aberration, increased distortion values, higher stray light levels and reduced resolving power. For inspection purposes, the distortion is often not so important. If the work pieces are illuminated with monochromatic light, then chromatic aberrations become unimportant. Therefore, for machine vision inspection purposes, the object side telecentric ray path can be straightforwardly achieved using a Fresnel lens front group. This is an alternative to the well known, but expensive, glass front lens solutions.

  5. 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.

  6. 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.

  7. Optical method for the surface topographic characterization of Fresnel lenses

    NASA Astrophysics Data System (ADS)

    Martínez Antón, Juan Carlos; Gómez Pedrero, José Antonio; Alonso Fernández, José; Quiroga, Juan Antonio

    2011-10-01

    Fresnel lenses and other faceted or micro-optic devices are increasingly used in multiple applications like solar light concentrators and illumination devices. As applications are more exigent this characterization is of increasing importance. We present a technique to characterize the surface topography of optical surfaces. It is especially well adapted to Fresnel lenses where abrupt surface slopes are usually difficult to handle in conventional techniques. The method is based on a new photometric strategy able to codify the height information in terms of optical absorption in a liquid. A detailed topographic map is simple to acquire by capturing images of the surface. Some experimental results are presented. A single pixel height resolution of ~0.1 μm is achieved for a height range of ~50 μm. A surface slope analysis is also made achieving a resolution of ~+/-0.15°.

  8. Process designed for experimentation for increased-caliper Fresnel lenses

    SciTech Connect

    Zderad, A.J.

    1992-04-01

    The feasibility of producing increased caliper linear and point focus Fresnel lenses in a continuous sheet is described. Both a 8.16-inch-square radial 2 {times} 7 parquet, and a 22-inch-wide linear lens were produced at .11-inch in caliper. The primary purpose of this experimentation is to determine the replication effectiveness and production rate of the polymeric web process at increased thickness. The results demonstrated that both radial and linear lenses, at increased caliper, can be replicated with performance comparable to that of the current state-of-the-art 3M laminated lenses; however, the radial parquets were bowed on the edges. Additional process development is necessary to solve this problem. Current estimates are that the .11-inch caliper parquets cost significantly more than customer laminated parquets using 0.022-inch thick lensfilm.

  9. 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.

  10. 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.)

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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. PMID:26367631

  19. 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

  20. 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.

  1. Fresnel lenses: study and fabrication in silicon technology for medium-IR applications

    NASA Astrophysics Data System (ADS)

    Fonollosa, Jordi; Rubio, Rafael; Hildenbrand, Jürgen; Moreno, Mauricio; Marco, Santiago; Santander, Joaquín; Fonseca, Luis; Hartwig, Susanne; Wöllenstein, Jürgen

    2006-04-01

    Diffractive Fresnel Lenses (FL) were designed, fabricated and tested. The lens aims for increasing the sensitivity of a Non-Dispersive InfraRed (NDIR) silicon based optical gas system, focusing as much radiation as possible onto the detector. The studied wavelengths are 10.6μm and 3.4μm, which are the main absorption lines for ethylene and ethanol respectively. The lens diameter (5mm) and the focal length (4mm) are fixed by the detector package. Those diffractive lenses are compatible with the planar nature of silicon microtechnology. A theoretical study about the global lens efficiency as a function of the technological constrains and the process complexity has been carried out. Using only three photolithographic masks, eight quantization steps can be etched and a theoretical lens efficiency of 95% can be achieved. Once the devices were fabricated, the focal length and the spot size have been measured.

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

    PubMed

    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

  3. 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.

  4. 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. PMID:27019460

  5. 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

  6. 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.

  7. Direct comparison of polymethylmetacrylate (PMMA) and silicone-on-glass (SOG) for Fresnel lenses in concentrating photovoltaics (CPV)

    NASA Astrophysics Data System (ADS)

    Annen, Hans Philipp; Fu, Ling; Leutz, Ralf; González, Luis; Mbakop, Jehu

    2011-09-01

    The CPV community is still undecided on one critical issue: what material to use best for Fresnel lens parquets. Reliability and longevity are the most important, but all other properties play roles as well. We have developed and manufactured Fresnel lenses with the two commonly used materials: PMMA (Polymethylmethacrylate) and silicone on glass (SOG). Both lenses are designed for the same optical train for best comparability. This allows for better understanding the pros and cons of the materials and making an informed choice for a specific CPV module. While PMMA lenses are embossed from pre-fab sheets in a hot-cold process, the silicone lenses are cast from a heat-curing silicone rubber at moderate temperatures, reducing the energy consumption. PMMA allows for the inclusion of custom low-profile 3D (2.5D) structures for module assembly and mechanical alignment, a feature not possible in silicone due to its low rigidity. Both lenses suffer from thermal expansion and refractive index change. While PMMA parquets expand isotropically, SOG prisms deform due to the difference of expansion coefficients between the glass and the silicone. SOG lenses are prone to delamination of the silicone film. The adhesive strength of the film to the glass can be measured using a modified blister test that we developed. The results show large difference with different materials and confirm the necessity of controlling this issue closely. While the small thermal expansion of the glass sheets allows for larger parquet sizes, the deformation of the prisms with temperature may cause a performance hit.

  8. 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. PMID:18752934

  9. Ultraviolet-light-treated polyimide alignment layers for polarization-independent liquid crystal Fresnel lenses

    NASA Astrophysics Data System (ADS)

    Hwang, S.-J.; Chen, T.-A.; Lin, K.-R.; Jeng, S.-C.

    2012-04-01

    The surface energy of a conventional homeotropic polyimide (PI) alignment layer was altered via ultraviolet (UV) light irradiation, and the pretilt angle of the PI was changed along with the surface energy. The surface energy can be controlled by either UV exposure time or irradiation intensity. A switchable liquid crystal Fresnel lens (LCFL) was created by the UV-treated alignment layers to form a Fresnel zone-distribution hybrid alignment, vertically aligned and hybrid aligned LC in the odd and even zones, respectively. The LCFL was made polarization-independent by circular buffing, and it had a diffraction efficiency of ˜22% at a low driving voltage of ˜1.2 V.

  10. 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. PMID:20389950

  11. Diffraction limited gamma-ray optics using Fresnel lenses for micro-arc second angular resolution

    NASA Astrophysics Data System (ADS)

    Skinner, G.; von Ballmoos, P.; Gehrels, N.; Krzmanic, J.

    2003-03-01

    Refractive indices at gamma-ray wavelengths are such that material thicknesses of the order of millimeters allow the phase of a wavefront to be changed by up to 2π . Thus a phase Fresnel lens can be made from a simple profiled thin disk of, for example, aluminium or plastic. Such a lens can easily have a collecting area of several square meters and an efficiency >90%. Ordinary engineering tolerances allow the manufacture of a lens which can be diffraction limited in the pico-meter wavelength band (up to ˜MeV) and thus provides a simple optical system with angular resolution better than a micro arc second i.e. the resolution necessary to resolve structures on the scale of the event horizon of super-massive black holes in AGN. However the focal length of such a lens is very long - up to a million km. Nevertheless studies have shown that a mission `Fresnel' using a detector and a phase Fresnel lens on two station-keeping spacecraft separated by such a distance is feasible. Results from these studies and work on other proof of concept studies are presented.

  12. Light weight aluminum optics

    NASA Astrophysics Data System (ADS)

    Catura, R. C.; Vieira, J. R.

    1985-09-01

    Light weight mirror blanks were fabricated by dip-brazing a core of low mass aluminum foam material to thin face sheets of solid aluminum. The blanks weigh 40% of an equivalent size solid mirror and were diamond turned to provide reflective surfaces. Optical interferometry was used to assess their dimensional stability over 7 months. No changes in flatness are observed (to the sensitivity of the measurements of a half wavelength of red light).

  13. 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. PMID:24787399

  14. 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.

  15. 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.

  16. 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)

  17. The Light-Weight Group Library

    Energy Science and Technology Software Center (ESTSC)

    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.

  18. 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.

  19. A Light-Weight Instrumentation System Design

    SciTech Connect

    Kidner, Ronald

    1999-06-02

    To meet challenging constraints on telemetry system weight and volume, a custom Light-Weight Instrumentation System was developed to collect vehicle environment and dynamics on a short-duration exo-atmospheric flight test vehicle. The total telemetry system, including electronics, sensors, batteries, and a 1 watt transmitter weighs about 1 kg. Over 80 channels of measurement, housekeeping, and telemetry system diagnostic data are transmitted at 128 kbps. The microcontroller-based design uses the automotive industry standard Controller Area Network to interface with and support in-flight control fimctions. Operational parameters are downloaded via a standard asynchronous serial communications intefiace. The basic design philosophy and functionality is described here.

  20. Method for the characterization of Fresnel lens flux transfer performance

    NASA Astrophysics Data System (ADS)

    Martinez Antón, Juan Carlos; Vázquez Moliní, Daniel; Muñoz de Luna, Javier; Gómez Pedrero, José Antonio; Fernández-Balbuena, Antonio Álvarez

    2011-10-01

    Fresnel lenses and other faceted or micro-optic devices are increasingly used in multiple applications like solar light concentrators and illumination devices, just to name some representative. However, it seems to be a certain lack of adequate techniques for the assessment of the performance of final fabricated devices. As applications are more exigent this characterization is a must. We provide a technique to characterize the performance of Fresnel lenses, as light collection devices. The basis for the method is a configuration where a camera images the Fresnel lens aperture. The entrance pupil of the camera is situated at the focal spot or the conjugate of a simulated solar source. In this manner, detailed maps of the performance of different Fresnel lenses are obtained for different acceptance angles.

  1. 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.

  2. 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

    2016-01-01

    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

  3. 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%.

  4. 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

  5. Light-weight radioisotope heater impact tests

    SciTech Connect

    Reimus, M.A.H.; Rinehart, G.H.; Herrera, A.

    1998-12-31

    The light-weight radioisotope heater unit (LWRHU) is a {sup 238}PuO{sub 2}-fueled heat source designed to provide one thermal watt in each of various locations on a spacecraft. Los Alamos National Laboratory designed, fabricated, and safety tested the LWRHU. The heat source consists of a hot-pressed {sup 238}PuO{sub 2} fuel pellet, a Pt-30Rh vented capsule, a pyrolytic graphite insulator, and a fineweave-pierced fabric graphite aeroshell assembly. To compare the performance of the LWRHUs fabricated for the Cassini mission with the performance of those fabricated for the Galileo mission, and to determine a failure threshold, two types of impact tests were conducted. A post-reentry impact test was performed on one of 180 flight-quality units produced for the Cassini mission and a series of sequential impact tests using simulant-fueled LWRHU capsules were conducted respectively. The results showed that deformation and fuel containment of the impacted Cassini LWRHU was similar to that of a previously tested Galileo LWRHU. Both units sustained minimal deformation of the aeroshell and fueled capsule; the fuel was entirely contained by the platinum capsule. Sequential impacting, in both end-on and side-on orientations, resulted in increased damage with each subsequent impact. Sequential impacting of the LWRHU appears to result in slightly greater damage than a single impact at the final impact velocity of 50 m/s.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Dynamic deformation analysis of light-weight mirror

    NASA Astrophysics Data System (ADS)

    Zhang, Yingtao; Cao, Xuedong; Kuang, Long; Yang, Wei

    2012-10-01

    In the process of optical dynamic target work, under the effort of the arm of dynamic target, the mirror needs to do circular motion, additional accelerated motion and uniform motion. The maximum acceleration is 10°/s2 and the maximum velocity is 30°/s. In this paper, we mostly analyze the dynamic deformation of a 600 mm honeycomb light-weight mirror of a certain dynamic target. Using the FEA (finite element analysis) method, first of all, we analyze the deformation of the light-weight mirror induced in gravity at different position; later, the dynamic deformation of light-weight mirror is analyzed in detailed. The analysis results indicate that, when the maximum acceleration is 10°/s2 and the maximum velocity is 30°/s, the centripetal force is 5% of the gravity at the equal mass, and the dynamic deformation of the mirror is 6.1% of the deformation induced by gravity.

  13. MPWide: Light-weight communication library for distributed computing

    NASA Astrophysics Data System (ADS)

    Groen, Derek; Rieder, Steven; Grosso, Paola; de Laat, Cees; Portegies Zwart, Simon

    2012-12-01

    MPWide is a light-weight communication library for distributed computing. It is specifically developed to allow message passing over long-distance networks using path-specific optimizations. An early version of MPWide was used in the Gravitational Billion Body Project to allow simulations across multiple supercomputers.

  14. Progress Toward Light Weight High Angular Resolution Multilayer Coated Optics

    NASA Astrophysics Data System (ADS)

    Ulmer, M. P.; Graham, M. E.; Vaynman, S.; Echt, J.; Farber, M.; Ehlert, S.; Varlese, S.

    2005-12-01

    We have been working on 3 separate projects that together will give us the ability to make 1 arc second, light weightWolter I optics that work above 40 keV. The three separate tasks are: (a) plasma spraying of metal-coated micro-balloons; (b) coating of the inside of Wolter I mirrors, (c) actuator designs for improving figure quality.We give a progress report on our work on all three areas.

  15. 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.

  16. Light-weight process groups in the Isis system

    NASA Astrophysics Data System (ADS)

    Glade, B. B.; Birman, K. P.; Cooper, R. C. B.; van Renesse, R.

    1993-09-01

    Isis is a toolkit for building applications consisting of cooperating processes in a distributed system. Group management and group communication are two basic building blocks provided by Isis. This approach has proven successful, and Isis' large user community is putting substantial demands on these mechanisms. To accommodate these demands a complete redesign of the system, called Horus, is being done to build a simpler and faster system that scales well. Of particular concern is the support and management of hundreds of thousands or more process groups. The paper describes a component of Horus known as light-weight process groups that addresses this scaling issue.

  17. Light-weight spherical mirrors for Cherenkov detectors

    NASA Astrophysics Data System (ADS)

    Cisbani, E.; Colilli, S.; Crateri, R.; Cusanno, F.; Fratoni, R.; Frullani, S.; Garibaldi, F.; Giuliani, F.; Gricia, M.; Iodice, M.; Iommi, R.; Lucentini, M.; Mostarda, A.; Pierangeli, L.; Santavenere, F.; Urciuoli, G. M.; De Leo, R.; Lagamba, L.; Nappi, E.; Braem, A.; Vernin, P.

    2003-01-01

    Light-weight spherical mirrors have been appositely designed and built for the gas threshold Cherenkov detectors of the two Hall A spectrometers. The mirrors are made of a 1 mm thick aluminized plexiglass sheet, reinforced by a rigid backing consisting of a phenolic honeycomb sandwiched between two carbon fiber mats epoxy glued. The produced mirrors have a thickness equivalent to 0.55% of radiation length, and an optical slope error of about 5.5 mrad. These characteristics make these mirrors suitable for the implementation in Cherenkov threshold detectors. Ways to improve the mirror features are also discussed in view of their possible employment in RICH detectors.

  18. 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.

  19. Hot Mix Asphalt Using Light Weight Aggregate Concrete

    NASA Astrophysics Data System (ADS)

    Awwad, Mohammad T.

    Hot mix asphalt concrete is produced by properly blending asphalt, coarse and fine aggregates in addition to filler at temperatures ranging from 80 to 165°C. This research is directed to study the effect of replacing the conventional aggregates by the recycled Light Weight Aggregate Concrete (LWAC) on the properties of the produced asphalt mix. The research studied the optimum asphalt content and the effect of some parameters on the properties of the recycled LWAC. The research included studying thirty-six Marshal Specimens lie in four main groups. Each group was made from crushed LWAC in addition to a comparison group used the pumice instead of the crushed LWAC. The LWAC mixes contained (0, 10, 15 and 20%) of silica powder content. The density, stability, flow, percentages of the air Voids in the Compacted Mixture (VTM), compacted mineral aggregate (VMA) and the Voids Filled by Asphalt (VFA) were investigated for all the studied specimens. The main conclusions drawn from the current research implies that the optimum percent of asphalt was 7.5% for the different percentages of silica powder ratios. The presence of voids in the light weight aggregates and the porosity of the obtained concrete affected largely the behavior of the obtained mix.

  20. 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.

  1. Overview of Selected Light-Weight Mirror Development Programs at GSFC

    NASA Technical Reports Server (NTRS)

    Keski-Kuha, Ritva A.; Content, David A.; Krebs, Carolyn (Technical Monitor)

    2001-01-01

    This paper discusses selected light-weight mirror development programs at GSFC, including development of light-weight, precision, low scatter imaging mirror for ultraviolet applications, foam core mirrors for visible and IR applications, and light-weight SiC mirrors.

  2. Fresnel Integral Equations: Numerical Properties

    SciTech Connect

    Adams, R J; Champagne, N J II; Davis, B A

    2003-07-22

    A spatial-domain solution to the problem of electromagnetic scattering from a dielectric half-space is outlined. The resulting half-space operators are referred to as Fresnel surface integral operators. When used as preconditioners for nonplanar geometries, the Fresnel operators yield surface Fresnel integral equations (FIEs) which are stable with respect to dielectric constant, discretization, and frequency. Numerical properties of the formulations are discussed.

  3. 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.

  4. Light weight underground pipe or cable installing device

    SciTech Connect

    Schosek, W. O.

    1985-01-08

    This invention pertains to a light weight underground pipe or cable installing device adapted for use in a narrow and deep operating trench. More particularly this underground pipe installing device employs a pair of laterally movable gates positioned adjacent the bottom of the operating trench where the earth is more solid to securely clamp the device in the operating trench to enable it to withstand the forces exerted as the actuating rod is forced through the earth from the so-called operating trench to the target trench. To accommodate the laterally movable gates positioned adjacent the bottom of the narrow pipe installing device, a pair of top operated double-acting rod clamping jaws, operated by a hydraulic cylinder positioned above the actuating rod are employed.

  5. Light-Weight Injector Technology for Cryogenic Mars Ascent Engines

    NASA Technical Reports Server (NTRS)

    Trihn, Huu Phuoc; Cramer, John M.

    1998-01-01

    Preliminary mission studies for human exploration of Mars have been performed at Marshall Space Flight Center (MSFC). These studies indicate that for chemical rockets only a cryogenic propulsion system would provide high enough performance to be considered for a Mars ascent vehicle. Although the mission is possible with Earth-supplied propellants for this vehicle, utilization of in-situ propellants is highly attractive. This option would significantly reduce the overall mass of launch vehicles. Consequently, the cost of the mission would be greatly reduced because the number and size of the Earth launch vehicle(s) needed for the mission decrease. NASA/Johnson Space Center has initiated several concept studies of in-situ propellant production plants. Liquid oxygen (LOX) is the primary candidate for an in-situ oxidizer. In-situ fuel candidates include methane (CH4), ethylene (C2H4), and methanol (CH3OH). MSFC initiated a technology development program for a cryogenic propulsion system for the Mars human exploration mission in 1998. One part of this technology program is the effort described here: an evaluation of propellant injection concepts for a LOX/liquid methane Mars Ascent Engine (MAE) with an emphasis on light-weight, high efficiency, reliability, and thermal compatibility. In addition to the main objective, hot-fire tests of the subject injectors will be used to test other key technologies including light-weight combustion chamber materials and advanced ignition concepts. This state-of-the-art technology will then be applied to the development of a cryogenic propulsion system that will meet the requirements of the planned Mars sample return (MSR) mission. The current baseline propulsion system for the MSR mission uses a storable propellant combination [monomethyl hydrazine/mixed oxides of nitrogen-25. However, a mission option that incorporates in-situ propellant production and utilization for the ascent stage is being carefully considered as a subscale

  6. 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.

  7. 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…

  8. 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.

  9. Experiences with Light Weight Fixed Wing Aerial Mapping UAVs

    NASA Astrophysics Data System (ADS)

    Mayr, W.

    2014-11-01

    UAVs seem to be the next "cloud" like topic, not only in geomatics. Unmanned Airborne Vehicles are not a wonder-tool, but a complementary approach to resolve some tasks more efficiently than before or at all. Since 2006 we commercially apply fixed wing, light weight UAVs for aerial mapping purposes. In this paper we like to share our experiences with UAVs of less than 5 kg and illuminate some limitations as well as potentials. Whereas multicopters seem to be in use everywhere, fixed wing UAVs more frequently seem to be applied in specific and geospatially oriented applications. Having processed several hundred UAV aerial mapping projects there forms a stable picture of this technology. Our impressions on durability, handling, and reliability of fixed wing UAVs get presented. We report on our day-to-day experiences and point to often simple hurdles to overcome. Various cameras were flown, different approaches of handling their geometries with different software packages were undertaken. Remarks to achieved geometric accuracies as well as the consequences of using dual frequency GPS instead of simple yet great single frequency GPS are discussed. All of this packed into the subsequent paper.

  10. Development of a Light Weight Pulse-Tube Cryocooler

    NASA Astrophysics Data System (ADS)

    Hiratsuka, Y.; Morishita, H.; Nomura, T.

    2004-06-01

    Examinations were done of a small-size Stirling-type pulse-tube cryocoolers developed for cooling high-temperature superconductor devices and semiconductor sensors. To satisfy the requirements for use in such devices, the Stirling-type pulse-tube cryocooler WE-SP2000, the conventional model, needed further improvement. The motor loss of the compressor was analyzed and the compressor efficiency of this model was improved to more than 70% against the 55% of the conventional model. Improvement of cooling efficiency through optimization of the pulse-tube form was also examined. Moreover, improvement of the U type pulse-tube cryocooler was examined, and nearly the same performance as an In-line type expander was achieved. As a result, an improvement in the cooling capacity by about 45% was attained in this model, for cooling capacity of 6.8W at 77K with compressor input power of 200W. A cooling capacity of 2W at 70K needed to cool high-temperature superconducting devices, the compressor input power was 70W. A re-examination of the materials for light weight resulted in the entire cryocooler weighing less than 9kg, with a height of 230mm, a width of 160mm excluding fan, and a length of 282mm. Moreover, the influence of the inclination exerted on the cooling capacity for differences in expander form was examined.

  11. Merging Technologies to Develop Light Weight X-ray Optics

    NASA Astrophysics Data System (ADS)

    Romaine, Suzanne

    We have made significant progress in our on-going program to develop higher resolution grazing incidence focusing hard X-ray optics for future missions. This proposal is for continued development of light weight optics for future hard X-ray missions. Our goal is to reduce the mass of the present full shell nickel replicated optics by more than half, while at the same time improving their resolution. The electroformed-nickel-replication process produces full shells of revolution, which are inherently stable with good figure control, offering the potential for good angular resolution. With angular resolution of 10 15 , such a telescope will improve the sensitivity by a factor of 5 over current planned high energy missions, and would lead to compelling new science which is central to NASA s Physics of the Cosmos Program. We have made significant progress over our previous period of performance and have achieved most of our goals including the first replication of a Wolter-1 mandrel using a metal-ceramic coating with an effective density of less than 4gm/cc. Achieving our goals will significantly advance the state-of-the-art for replicated full shell telescopes and will lower the cost for future NASA X-ray astronomy missions of moderate resolution.

  12. Design of Mwir Continuous Zoom with Light Weight

    NASA Astrophysics Data System (ADS)

    Ge, J. J.; Qin, Y.; Deng, D. B.

    2013-08-01

    A thermal imaging continuous zoom system is developed with light weight for airborne optoelectronic detection and tracking apparatus. The continuous zoom system provides 4× zoom range from the focal of 37.5 mm to 150 mm. Based on the cool 640 × 512 detector with staring focal plane array (FPA), an optical system of middle infrared continuous zoom system is designed for airborne optoelectronic detection and tracking apparatus. The system is composed of a zoom system, a secondary imaging system and two reflectors. In order to improving the system performance, the whole system is adding four aspheric surfaces. The design results prove that the system worked at 3.7-4.8 μm has achieved the zoom of 37.5-150 mm, large zoom ratio of 4× and F number of 4, which can obtain the cold shield efficiency of 100% and the MTF more than 0.4 at the spatial frequency of 32 lp/mm closing to the diffraction limit. The overall lens length is 280 mm and the weight is 197 g. The optical system has the advantages of small volume, high image quality and simple structure.

  13. Phosphorus sorption characteristics of a light-weight aggregate.

    PubMed

    Zhu, T; Maehlum, T; Jenssen, P D; Krogstad, T

    2003-01-01

    A light-weight aggregate (LWA) made of expanded clay used as a filter media in wastewater treatment, was tested for sorption of phosphorus (P) in laboratory experiments. The objectives were to investigate the different P retention pools and how grain size, time, temperature and changed P concentration influenced the P binding mechanisms in this type of filter. Three different grain sizes (0-2 mm, 2-4 mm and 0-4 mm) were tested in a batch experiment. The isotherm for the P sorbed by the contact medium (including retention and fixation) was obtained under laboratory conditions. Fifty percent of the P sorption occurred in the first 4-8 hours. Temperature did not substantially influence P sorption for 0-2 mm grain size LWA. In the LWA suspension system, P desorption did not occur when the P content in the loading solution decreased. Fractionation analysis indicated that Ca-bound P, loosely-bound P, and Al-bound P were the predominant P retention pools. The loosely-bound P pool was determined primarily by the equilibrated P concentration in the system. Fe-bound P was negligible in the P sorption of LWA. PMID:14621152

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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

  20. Efficient Fresnel x-ray optics made simple.

    PubMed

    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. PMID:17446906

  1. 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, ...

  2. Cylindrically symmetric Fresnel lens for high concentration photovoltaic

    NASA Astrophysics Data System (ADS)

    Hung, Yu-Ting; Su, Guo-Dung

    2009-08-01

    High concentration photovoltaic (HCPV) utilizes point-focus cost-effective plastic Fresnel lens. And a millimeter-sized Ill-V compound multi-junction solar cell is placed underneath focusing optics which can achieve cell efficiency potential of up to 40.7 %. The advantage of HCPV makes less solar cell area and higher efficiency; however, the acceptance angle of HCPV is about +/-1°, which is very small and the mechanical tracking of the sun is necessary. In order to reduce the power consumption and the angle tracking error of tracking systems, a light collector model with larger acceptance angle is designed with ZEMAX®. In this model, the original radially symmetric Fresnel lens of HCPV is replaced by cylindrically symmetric Fresnel lens and a parabolic reflective surface. Light is collected in two dimensions separately. And a couple of lenses and a light pipe are added before the solar cell chip in order to collect more light when sun light deviates from incident angle of 00. An acceptance angle of +/-10° is achieved with GCR 400.

  3. 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

    2010-06-01

    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 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. PMID:20401422

  4. 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

  5. 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

    2016-09-01

    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. PMID:27607727

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. Fabrication of wedged multilayer Laue lenses

    DOE PAGESBeta

    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.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

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Design of an efficient Fresnel-type lens utilizing double total internal reflection for solar energy collection.

    PubMed

    Wallhead, Ian; Jiménez, Teresa Molina; Ortiz, Jose Vicente García; Toledo, Ignacio Gonzalez; Toledo, Cristóbal Gonzalez

    2012-11-01

    A novel of Fresnel-type lens for use as a solar collector has been designed which utilizes double total internal reflection (D-TIR) to optimize collection efficiency for high numerical aperture lenses (in the region of 0.3 to 0.6 NA). Results show that, depending on the numerical aperture and the size of the receiver, a collection efficiency theoretical improvement on the order of 20% can be expected with this new design compared with that of a conventional Fresnel lens. PMID:23326849

  17. 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.

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

    PubMed

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

    2010-11-01

    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. PMID:21164696

  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. 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.

  1. 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.

  2. Design of single layer subwavelength diffractive optical element (G-Fresnel) for spectrum splitting and beam concentration

    NASA Astrophysics Data System (ADS)

    Albarazanchi, Abbas; Gerard, Philippe; Ambs, Pierre; Meyrueis, Patrick

    2014-05-01

    There is an increasing demand for optical elements having the functionalities of hybrid devices, such as the combination of a Fresnel lens and a diffraction grating. These new devices can be used in many applications, such as in optical spectrometers, optical precision measurement systems and diffractive optical systems for enhancing the efficiency of third generation photovoltaic solar cells. There is also a growing need for developments of a cost-effective technology to fabricate compact optical devices. Therefore the motivation of our project is to find a new model of the G-Fresnel (i.e. grating and Fresnel lens) taking into account the utilization of the electromagnetic theory for the rigorous analysis of its behavior. In this paper, a novel method is proposed and employed to design a G-Fresnel device that has only one structure layer with subwavelength features, and that focuses and separates different bands of light spectra in the same focal plane. The device performance has been studied through the use of rigorous electromagnetic theory, by using the Finite Difference Time Domain (FDTD) for the study of the near field and the Angular Spectrum Method (ASM) for the study of the propagation in the far field. The optimal design of the G-Fresnel profiles depends on the profile of the Fresnel lenses that minimize the longitude chromatic aberration, and also on the diffraction grating with high first order diffraction efficiency. The verification of the G-Fresnel model that we propose shows high diffraction efficiency and a good performance in separation for a broadband light spectrum. This promising G-Fresnel model could be used to increase the efficiency of third generation photovoltaic cells.

  3. 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.

  4. Digital spatially incoherent Fresnel holography

    NASA Astrophysics Data System (ADS)

    Rosen, Joseph; Brooker, Gary

    2007-04-01

    We present a new method for recording digital holograms under incoherent illumination. Light is reflected from a 3D object, propagates through a diffractive optical element (DOE), and is recorded by a digital camera. Three holograms are recorded sequentially, each for a different phase factor of the DOE. The three holograms are superposed in the computer, such that the result is a complex-valued Fresnel hologram. When this hologram is reconstructed in the computer, the 3D properties of the object are revealed.

  5. 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.

  6. Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Saha, P.; Murdin, P.

    2000-11-01

    Gravity bends light rays in a way analogous to, but quantitatively different from, the way it bends trajectories of passing particles. If light from some bright object passes close enough to some foreground mass, that object's image will be altered. The effect is more like a piece of bathroom glass in the sky than a precision-ground and well-focused lens, but the terms `gravitational lensing' or ...

  7. 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.

  8. 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).

  9. 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. PMID:26836072

  10. 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 ...

  11. Regression Model for Light Weight and Crashworthiness Enhancement Design of Automotive Parts in Frontal CAR Crash

    NASA Astrophysics Data System (ADS)

    Bae, Gihyun; Huh, Hoon; Park, Sungho

    This paper deals with a regression model for light weight and crashworthiness enhancement design of automotive parts in frontal car crash. The ULSAB-AVC model is employed for the crash analysis and effective parts are selected based on the amount of energy absorption during the crash behavior. Finite element analyses are carried out for designated design cases in order to investigate the crashworthiness and weight according to the material and thickness of main energy absorption parts. Based on simulations results, a regression analysis is performed to construct a regression model utilized for light weight and crashworthiness enhancement design of automotive parts. An example for weight reduction of main energy absorption parts demonstrates the validity of a regression model constructed.

  12. The optimization of collimator's light-weighting structure based on MOBIE system of TMT

    NASA Astrophysics Data System (ADS)

    Chen, Hong; Chen, Yi; Hu, Zhongwen; Xu, Mingming; Ji, Hangxin; Wang, Lei

    2015-10-01

    Design a best light-weighting collimator to conform to the requirements of opto-mechanical design. Good surface accuracy is our aim, based on a less mass. The ratio of diameter to thickness, the type, size and thickness of pocket, the thickness of the mirror, the support size and position, the thickness of the wall and so on is concerned. Besides, comparing two kinds material is also discussed. In addition, we consider the situation that the orientation vary in support plane. Use the orthogonal table to analyze these elements, and find the better methods. According to the analysis in ANSYS, the collimator mass can reduce to 103 kg, below 159 kg; the ratio of light-weight can reach 70%; the peak-valley value is below 100 nm, that meets the request of below 200 nm.

  13. 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.

  14. 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.

  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). PMID:19458729

  16. 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.

  17. 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. PMID:27472584

  18. Zone-Doubled Fresnel Zone Plates for Scanning Transmission X-ray Microscopy

    NASA Astrophysics Data System (ADS)

    Vila-Comamala, J.; Gorelick, S.; Färm, E.; Kewish, C. M.; Diaz, A.; Guzenko, V. A.; Barrett, R.; Raabe, J.; Menzel, A.; Bunk, O.; Ritala, M.; David, C.

    2011-09-01

    We demonstrate the highest spatial resolution reported in scanning transmission x-ray microscopy to date. For the first time in x-ray microscopy, features below 10 nm in width were resolved in the soft x-ray regime (1.2 keV) and 20-nm lines and spaces were visible at multi-keV photon energies (6.2 keV). These achievements were accomplished using zone-doubled Fresnel zone plates. These lenses were fabricated by combining electron-beam lithography and atomic layer deposition of iridium. Diffraction efficiencies up to 8% were measured for zone-doubled Fresnel zone plates with an outermost zone width of 25 nm at 6.2-keV photon energy.

  19. Light-weight X-ray optics for XEUS: alternative technologies

    NASA Astrophysics Data System (ADS)

    Hudec, R.; Pina, L.; Inneman, I.; Brovzek, V.; Chraska, P.; Neufuss, K.; Zentkova, M.; Zentko, A.

    The XEUS mission requires very light-weight but large and precise X-ray mirror shells. Clearly, the developments of innovative techniques and approaches are necessary. We discuss the possible alternative techniques with focus on the technologies and experience available in the Czech Republic. They include light ceramics replication by plasma spraying as well as by CVD and PVD technologies, SiC, thin glass technology, improved electroforming, composites, as well as glossy metals.

  20. 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.

  1. Rough Fresnel zone plates over metallic surfaces.

    PubMed

    Salgado-Remacha, Francisco Javier; Sanchez-Brea, Luis Miguel; Alvarez-Rios, Francisco Javier; Bernabeu, Eusebio

    2010-04-01

    We analyze the focusing properties of Fresnel zone plates fabricated over steel tapes using laser ablation. Our intention is to implement the use of micro-optical elements when the use of conventional chrome-glass elements is not indicated. Because of the manufacture process, the surface presents a certain anisotropic roughness, which reduces the focusing properties. First, we develop numerical simulations by means of the Rayleigh-Sommerfeld approach, showing how roughness in both levels of the Fresnel zone plate affects the focalization of the lens. We also manufacture Fresnel zone plates over steel tape, and perform experimental verification that corroborates the numerical results. PMID:20357856

  2. 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.

  3. 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.

  4. 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.

  5. Glasses and Contact Lenses

    MedlinePlus

    ... Here's Help White House Lunch Recipes Glasses and Contact Lenses KidsHealth > For Kids > Glasses and Contact Lenses Print A A A Text Size What's ... together the way they should. But eyeglasses or contact lenses, also called corrective lenses, can help most ...

  6. 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.

  7. 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.

  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. The trials (and tribulations) of light-weight UAV optical system design

    NASA Astrophysics Data System (ADS)

    Palmer, Troy A.; Alexay, Christopher C.

    2007-04-01

    Increasing demands for thermal imaging systems on unmanned aerial vehicles have led to a concentrated effort in the design and development of light weight infrared optical systems. Pre-engineered or commercially available infrared lens assemblies are typically unsuitable for such low mass and volume constrained applications. This paper will focus on the challenging aspects and design considerations employed to minimize the weight of the refractive elements as well as the associated opto-mechanical support housings. In particular, consideration will be directed towards the hurdles associated with the manufacture of systems intended to operate in this unique branch of surveillance optics.

  11. 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.

  12. MPWide: a light-weight library for efficient message passing over wide area networks

    NASA Astrophysics Data System (ADS)

    Groen, D.; Rieder, S.; Portegies Zwart, S.

    2013-12-01

    We present MPWide, a light weight communication library which allows efficient message passing over a distributed network. MPWide has been designed to connect application running on distributed (super)computing resources, and to maximize the communication performance on wide area networks for those without administrative privileges. It can be used to provide message-passing between application, move files, and make very fast connections in client-server environments. MPWide has already been applied to enable distributed cosmological simulations across up to four supercomputers on two continents, and to couple two different bloodflow simulations to form a multiscale simulation.

  13. Optomechanical analysis of a 1-m light-weight mirror system

    NASA Astrophysics Data System (ADS)

    Kihm, Hagyong; Yang, Ho-Soon; Lee, Yun-Woo

    2013-05-01

    We present the optomechanical analysis results for a 1-m light-weight mirror system for a space telescope. The mirror has partially-closed pockets at the back surface and three square bosses at the rim for flexure mounting. The mirror design is optimized to satisfy the performance requirements under launch loads and a space environment. Mirror surface distortions due to gravity, assembly, isothermal loads, and moisture absorption are investigated. Mechanical safety issues such as mirror fracture, flexure yielding, and adhesive breakage are also examined.

  14. Light weight airborne imaging spectrometer remote sensing system for mineral exploration in China

    NASA Astrophysics Data System (ADS)

    Wu, Taixia; Zhang, Lifu; Cen, Yi; Wang, Jinnian; Tong, Qingxi

    2014-05-01

    Imaging spectrometers provide the unique combination of both spatially contiguous spectra and spectrally contiguous images of the Earth's surface that allows spatial mapping of these minerals. One of the successful applications of imaging spectrometers remote sensing identified was geological mapping and mineral exploration. A Light weight Airborne Imaging Spectrometer System (LAISS) has been developed in China. The hardware of the compact LAISS include a VNIR imaging spectrometer, a SWIR imaging spectrometer, a high resolution camera and a position and attitude device. The weight of the system is less than 20kg. The VNIR imaging spectrometer measures incoming radiation in 344 contiguous spectral channels in the 400-1000 nm wavelength range with spectral resolution of better than 5 nm and creates images of 464 pixels for a line of targets with a nominal instantaneous field of view (IFOV) of ~1 mrad. The SWIR imaging spectrometer measures incoming radiation in the 1000-2500 nm wavelength range with spectral resolution of better than 10 nm with a nominal instantaneous field of view (IFOV) of ~2 mrad. The 400 to 2500nm spectral range provides abundant information about many important Earth-surface minerals. A ground mineral scan experiment and an UAV carried flying experiment has been done. The experiment results show the LAISS have achieved relative high performance levels in terms of signal to noise ratio and image quality. The potential applications for light weight airborne imaging spectrometer system in mineral exploration are tremendous.

  15. Single crystal scintillator plates used for light weight material X-ray radiography

    NASA Astrophysics Data System (ADS)

    Tous, J.; Blazek, K.; Nikl, M.; Mares, J. A.

    2013-03-01

    Very thin scintillator imaging plates have recently become of great interest. In high resolution X-ray projection imaging, very thin scintillators of about 5-20 micrometres are used to achieve high spatial resolution. Such thin screens are mainly used in micro-CT and nano-CT systems with either micro-focus X-ray tubes or with synchrotron sources. This work deals with a high resolution CCD camera in connection with an optical system and different single crystal scintillators in application for low energy X-ray micro-radiography. The thin screens used were prepared by mechanical polishing from Y3Al5O12 or Lu3Al5O12 single crystals. The screens can be used in equipment for the detection of different kinds of radiation and particles (UV, VUV, electrons or ions or their beams, X- or gamma-rays). A high resolution open type micro-focus X-ray tube was used to achieve the high resolution. The results show that the single crystal plates exhibit high spatial resolution and high sensitivity to low energy X-rays resulting in high image contrast. The use of the plates is highly suitable for light weight (low Z) material X-ray radiography. The resolution achieved is demonstrated using a test grid. Several light weight objects are imaged using the thin plates.

  16. 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. PMID:25607497

  17. 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...

  18. 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...

  19. 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...) 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...

  20. 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...) 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...

  1. 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...

  2. 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...

  3. 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...

  4. 21 CFR 886.1390 - Flexible diagnostic Fresnel lens.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 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...

  5. 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...

  6. 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...

  7. 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.

  8. Fresnel filtering of Gaussian beams in microcavities.

    PubMed

    Shinohara, Susumu; Harayama, Takahisa; Fukushima, Takehiro

    2011-03-15

    We study the output from the modes described by the superposition of Gaussian beams confined in the quasi-stadium microcavities. We experimentally observe the deviation from Snell's law in the output when the incident angle of the Gaussian beam at the cavity interface is near the critical angle for total internal reflection, providing direct experimental evidence on the Fresnel filtering. The theory of the Fresnel filtering for a planar interface qualitatively reproduces experimental data, and a discussion is given on small deviation between the measured data and the theory. PMID:21403763

  9. 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.

  10. 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.

  11. A small, light-weight, low-power, multichannel wireless neural recording microsystem.

    PubMed

    Borna, Amir; Marzullob, Timothy; Gage, Greg; Najafi, Khalil

    2009-01-01

    A small (<1cm(3)), light-weight (<1g including batteries), low power (10mW, lasts 25 hrs), long range (22 ft.), 3-channel wireless neural recording system is designed, fabricated and characterized through in-vitro and in-vivo experiments. The transmitter comprises of an ASIC fabricated in 2-Poly, 2-Metal 1.5 microm AMIS process which can transmit data out wirelessly using on-chip VCO or low power commercial off-the-shelf (COTS) transmitters. The microsystem is employed in collecting neural signals from two different animal models: axons in cockroach leg and forelimb area of the motor cortex of a mature Long Evans rat. PMID:19963909

  12. 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.

  13. 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.

  14. Design and development of an advanced technology light weight receiver for phase array applications

    NASA Astrophysics Data System (ADS)

    Bayar, Esen

    1987-10-01

    A light weight L-band receiver for application to spacecraft multiple beam phased array front ends is discussed, with emphasis on the design of the low noise amplifiers and the RF filter. The receiver is designed to operate in the Inmarsat frequency band of 1626.5-1656.5 MHz, with a single down conversion to an intermediate frequency of 250 MHz. Performance parameters include an overall noise figure of 1.5 dB with an associated gain of 60 dB and a multicarrier C/I3 of 90 dB over an acceptance temperature range of -5 C to 55 C. The mass target of 200 g should be achievable.

  15. Light weight, high field, stable, superconducting magnets for advanced transportation systems

    SciTech Connect

    Lubell, M.S.; Dresner, L.; Kenney, W.J.; Lue, J.W.; Luton, J.N.; Schwenterly, S.W.

    1991-01-01

    Although the Guideway may be the most expensive component of a MAGLEV system, the importance of a suitable magnet system should not be underestimated. The reliability of operation of MAGLEV depends on the superconducting magnets performing to their specifications in a reliable manner (i.e., without training or quenching). Besides reliability the magnets should produce high field, be sufficiently stable to withstand reasonable perturbations, be light weight, be protected in the event of a quench, and be economical (although performance should outweigh cost). We propose to develop superconducting magnets that have these features. Our magnet designs are based on internally cooled, cable-in-conduit superconductor with Polymer Matrix Composites (PMC) as the structural reinforcement. Although the initial work is with metallic superconductors such as NbTi, the processes being developed will be applicable to the High Temperature Ceramic Superconductors when they become suitable for magnet applications.

  16. 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).

  17. Gradient Refractive Index Lenses.

    ERIC Educational Resources Information Center

    Morton, N.

    1984-01-01

    Describes the nature of gradient refractive index (GRIN) lenses, focusing on refraction in these materials, focal length of a thin Wood lens, and on manufacturing of such lenses. Indicates that GRIN lenses of small cross section are in limited production with applications suggested for optical communication and photocopying fields. (JN)

  18. 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

  19. Broadband waveplate lenses.

    PubMed

    Tabiryan, Nelson V; Serak, Svetlana V; Nersisyan, Sarik R; Roberts, David E; Zeldovich, Boris Ya; Steeves, Diane M; Kimball, Brian R

    2016-04-01

    We report on lenses that operate over the visible wavelength band from 450 nm to beyond 700 nm, and other lenses that operate over a wide region in the near-infrared from 650 nm to beyond 1000 nm. Lenses were recorded in liquid crystal polymer layers only a few micrometers thick, using laser-based photoalignment and UV photopolymerization. Waveplate lenses allowed focusing and defocusing laser beams depending on the sign of the circularity of laser beam polarization. Diffraction efficiency of recorded waveplate lenses was up to 90% and contrast ratio was up to 500:1. PMID:27137003

  20. Optical Fresnel transformation and quantum tomography

    NASA Astrophysics Data System (ADS)

    Fan, Hong-Yi; Hu, Li-yun

    2009-09-01

    Corresponding to optical Fresnel transformation characteristic of a ray transfer matrix (A,B,C,D),AD-BC=1, there exists Fresnel operator F(A,B,C,D) in quantum optics, we show that under the Fresnel transformation the pure-state position density ∣x>ssFresnel quadrature phase is the tomography (Radon transform of the Wigner function), correspondingly, s=. Similarly, we find F∣p>sp=∫∫-∞∞dp'dx'δp-Ax'-Cp')Δx',p', where ∣p>

  1. 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)

  2. 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

  3. Next Generation X-Ray Optics: High-Resolution, Light-Weight, and Low-Cost

    NASA Technical Reports Server (NTRS)

    Zhang, William W.

    2012-01-01

    X-ray telescopes are essential to the future of x-ray astronomy. In this talk I will describe a comprehensive program to advance the technology for x-ray telescopes well beyond the state of the art represented by the three currently operating missions: Chandra, XMM-Newton, and Suzaku. This program will address the three key issues in making an x-ray telescope: (1) angular resolution, (2) effective area per unit mass, and (3) cost per unit effective area. The objectives of this technology program are (1) in the near term, to enable Explorer-class x-ray missions and an IXO-type mission, and (2) in the long term, to enable a flagship x-ray mission with sub-arcsecond angular resolution and multi-square-meter effective area, at an affordable cost. We pursue two approaches concurrently, emphasizing the first approach in the near term (2-5 years) and the second in the long term (4-10 years). The first approach is precision slumping of borosilicate glass sheets. By design and choice at the outset, this technique makes lightweight and low-cost mirrors. The development program will continue to improve angular resolution, to enable the production of 5-arcsecond x-ray telescopes, to support Explorer-class missions and one or more missions to supersede the original IXO mission. The second approach is precision polishing and light-weighting of single-crystal silicon mirrors. This approach benefits from two recent commercial developments: (1) the inexpensive and abundant availability of large blocks of monocrystalline silicon, and (2) revolutionary advances in deterministic, precision polishing of mirrors. By design and choice at the outset, this technique is capable of producing lightweight mirrors with sub-arcsecond angular resolution. The development program will increase the efficiency and reduce the cost of the polishing and the light-weighting processes, to enable the production of lightweight sub-arcsecond x-ray telescopes. Concurrent with the fabrication of lightweight

  4. 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

  5. Atmospheric profiles of Black Carbon at remote locations using light-weight airborne Aethalometers

    NASA Astrophysics Data System (ADS)

    Hansen, A. D.; Močnik, G.; Drinovec, L.; Lenarcic, M.

    2012-12-01

    While measurements of atmospheric aerosols are routinely performed at ground-level around the world, there is far less knowledge of their concentrations at altitude: yet this data is a crucial requirement for our understanding of the dispersion of pollutants of anthropogenic origin, with their associated effects on radiative forcing, cloud condensation, and other adverse phenomena. Black Carbon (BC) is a unique tracer for combustion emissions, and can be detected rapidly and with great sensitivity by filter-based optical methods. It has no non-combustion sources and is not transformed by atmospheric processes. Recent technical advances have developed light-weight miniaturized instruments which can be operated on light aircraft or carried aboard commercial passenger flights. From January to April 2012, a single-seat ultra-light aircraft flew around the world on a scientific, photographic and environmental-awareness mission. The flight track crossed all seven continents and all major oceans, with altitudes up to 8.9 km ASL. The aircraft carried a custom-developed high-sensitivity dual-wavelength light-weight Aethalometer, operating at 370 and 880 nm with special provision to compensate for the effects of changing pressure, temperature and humidity. The instrument recorded BC concentrations with high temporal resolution and sensitivity better than 5 ng/m3. We present examples of data from flight tracks over remote oceans, uninhabited land masses, and densely populated areas, analyzing the spectral dependence of absorption to infer the contributions to BC from fossil fuel vs. biomass combustion, and aggregating the data into vertical profiles. The regional and long range transport of BC may be investigated using back-trajectories. We have also operated miniature instruments in the passenger cabins of long-distance commercial aircraft. Since there are no combustion sources within the cabin, any BC in the ventilation air must necessarily have originated from the outside

  6. 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.

  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. A computational analysis of the ballistic performance of light-weight hybrid composite armors

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Pandurangan, B.; Koudela, K. L.; Cheeseman, B. A.

    2006-11-01

    The ability of hybrid light-weight fiber-reinforced polymer-matrix composite laminate armor to withstand the impact of a fragment simulating projectile (FSP) is investigated using a non-linear dynamics transient computational analysis. The hybrid armor is constructed using various combinations and stacking sequences of a high-strength/high-stiffness carbon fiber-reinforced epoxy (CFRE) and a high-ductility/high-toughness Kevlar fiber-reinforced epoxy (KFRE) composite laminates of different thicknesses. The results obtained indicate that at a fixed thickness of the armor both the stacking sequence and the number of CFRE/KFRE laminates substantially affect the ballistic performance of the armor. Specifically, it is found that the armor consisting of one layer of KFRE and one layer of CFRE, with KFRE laminate constituting the outer surface of the armor, possesses the maximum resistance towards the projectile-induced damage and failure. The results obtained are rationalized using an analysis of the elastic wave reflection and transmission behavior at the inter-laminate and laminate/air interfaces.

  9. 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).

  10. Direct Georeferencing with on Board Navigation Components of Light Weight Uav Platforms

    NASA Astrophysics Data System (ADS)

    Pfeifer, N.; Glira, P.; Briese, C.

    2012-08-01

    Unmanned aerial vehicles (UAV) are a promising platform for close range airborne photogrammetry. Next to the possibility of carrying certain sensor equipment, different on board navigation components may be integrated. These devices are getting, due to recent developments in the field of electronics, smaller and smaller and are easily affordable. Therefore, UAV platforms are nowadays often equipped with several navigation devices in order to support the remote control of a UAV. Furthermore, these devices allow an automated flight mode that allows to systematically sense a certain area or object of interest. However, next to their support for the UAV navigation they allow the direct georeferencing of synchronised sensor data. This paper introduces the direct georeferencing of airborne UAV images with a low cost solution based on a quadrocopter. The system is equipped with a Global Navigation Satellite System (GNSS), an Inertial Measurement Unit (IMU), an air pressure sensor, a magnetometer, and a small compact camera. A challenge using light weight consumer-grade sensors is the acquisition of high quality images with respect to brightness and sharpness. It is demonstrated that an appropriate solution for data synchronisation and data processing allows a direct georeferencing of the acquired images with a precision below 1m in each coordinate. The precision for roll and pitch is below 1° and for the yaw it is 2.5°. The evaluation is based on image positions estimated based on the on board sensors and compared to an independent bundle block adjustment of the images.

  11. A tele-operated mobile ultrasound scanner using a light-weight robot.

    PubMed

    Delgorge, Cécile; Courrèges, Fabien; Al Bassit, Lama; Novales, Cyril; Rosenberger, Christophe; Smith-Guerin, Natalie; Brù, Concepció; Gilabert, Rosa; Vannoni, Maurizio; Poisson, Gérard; Vieyres, Pierre

    2005-03-01

    This paper presents a new tele-operated robotic chain for real-time ultrasound image acquisition and medical diagnosis. This system has been developed in the frame of the Mobile Tele-Echography Using an Ultralight Robot European Project. A light-weight six degrees-of-freedom serial robot, with a remote center of motion, has been specially designed for this application. It holds and moves a real probe on a distant patient according to the expert gesture and permits an image acquisition using a standard ultrasound device. The combination of mechanical structure choice for the robot and dedicated control law, particularly nearby the singular configuration allows a good path following and a robotized gesture accuracy. The choice of compression techniques for image transmission enables a compromise between flow and quality. These combined approaches, for robotics and image processing, enable the medical specialist to better control the remote ultrasound probe holder system and to receive stable and good quality ultrasound images to make a diagnosis via any type of communication link from terrestrial to satellite. Clinical tests have been performed since April 2003. They used both satellite or Integrated Services Digital Network lines with a theoretical bandwidth of 384 Kb/s. They showed the tele-echography system helped to identify 66% of lesions and 83% of symptomatic pathologies. PMID:15787007

  12. 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.

  13. 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.

  14. Development of a light-weight, wind-turbine-rotor-based data acquisition system

    SciTech Connect

    Berg, D.E.; Rumsey, M.; Robertson, P.; Kelley, N.; McKenna, E.; Gass, K.

    1997-12-01

    Wind-energy researchers at Sandia National Laboratories (SNL) and the National Renewable Energy Laboratory (NREL) are developing a new, light-weight, modular system capable of acquiring long-term, continuous time-series data from current-generation small or large, dynamic wind-turbine rotors. Meetings with wind-turbine research personnel at NREL and SNL resulted in a list of the major requirements that the system must meet. Initial attempts to locate a commercial system that could meet all of these requirements were not successful, but some commercially available data acquisition and radio/modem subsystems that met many of the requirements were identified. A time synchronization subsystem and a programmable logic device subsystem to integrate the functions of the data acquisition, the radio/modem, and the time synchronization subsystems and to communicate with the user have been developed at SNL. This paper presents the data system requirements, describes the four major subsystems comprising the system, summarizes the current status of the system, and presents the current plans for near-term development of hardware and software.

  15. 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.

  16. Laser: a tool for light weight steel solutions for the automotive industry

    NASA Astrophysics Data System (ADS)

    Prange, Wilfried; Wonneberger, Ingo

    2003-03-01

    Mid 80th the steel industry discovered the laser as a tool to develop new products made from steel -- the tailored blanks. That means welding single blanks together, which are of different gauge or grades and coating. In the meantime this product is one of the key solutions for light weight vehicles with increasing performances. The market development world wide confirms this statement. But the development of this product is still going on. New high power lasers and new laser generations as Nd:YAG lasers are the basis. Today welded blanks with almost any seam/blank configuration are in high volume production. These blanks offer an additional potential for the optimization of the final product. To produce flat blank is only one possibility. New developments are the tailored tubes as a prematerial for the hydroforming process. This product becomes more and more important for optimized body in white solutions. But this design elements need new solutions in the assembly shops. So the laser is going to get more importance in the 3D welding process as well. This was shown for example in the ULSAB(-AVC)-project. Future vehicles more and more contain different materials. For example the joining of steel and aluminum to Hybrid Blanks can be done successfully by the use of laser. So the laser is one of the most important tools in the future.

  17. 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.

  18. Printed resistive strain sensors for monitoring of light-weight structures

    NASA Astrophysics Data System (ADS)

    Rausch, J.; Salun, L.; Griesheimer, S.; Ibis, M.; Werthschützky, R.

    2011-04-01

    In this paper we present the design and test of printed strain sensors, which can be integrated in light-weight structures for monitoring purposes. We focus on composite structures consisting of metal substrate as well as insulating and conductive ink layers for sensing normal strain at the surface. Both, inkjet and screen printing technology are used to realize resistive topologies that can be evaluated using a Wheatstone bridge configuration. In a first step, we analyze electrical properties of functional inks: electrical impedance and breakdown electrical field strength in case of insulation inks, resistance in case of conducting inks. Silver and PEDOT:PSS based suspensions are printed as sensing layer. To determine the resistance change due to plastic deformation of the metal substrate, tensile tests are performed up to 30% strain and subsequent resistance change is measured. In a second step, the sensing effect of printed conductive structures is investigated. Resistive sensing topologies are designed for detecting longitudinal and transversal normal strain. Meander structures, which form single resistors as well as bridge configurations, are printed on test specimens and analyzed in a four-point bending set up. Performing loading and unloading cycles, gauge factor, cross sensitivity, nonlinearity and hysteresis error of the sensors are measured.

  19. First high dynamic range and high resolution images of the sky obtained with a diffractive Fresnel array telescope

    NASA Astrophysics Data System (ADS)

    Koechlin, Laurent; Rivet, Jean-Pierre; Deba, Paul; Serre, Denis; Raksasataya, Truswin; Gili, René; David, Jules

    2012-03-01

    This paper presents high contrast images of sky sources, obtained from the ground with a novel optical concept: Fresnel arrays. We demonstrate the efficiency of a small 20 cm prototype Fresnel array for making images with high brightness ratios, achieving contrasts up to 4 × 105 on sky sources such as Mars and its satellites, and the Sirius A-B couple. These validation results are promising for future applications in space, for example the 4 m array we have proposed to ESA in the frame of the "Call for a Medium-size mission opportunity for a launch in 2022". Fresnel imagers are the subject of a topical issue of Experimental Astronomy published in 2011, but only preliminary results were presented at the time. Making images of astronomical bodies requires an optical component to focus light. This component is usually a mirror or a lens, the quality of which is critical for sharp and high contrast images. However, reflection on a mirror and refraction through a lens are not the only ways to focus light: an alternative is provided by diffraction through binary masks (opaque foils with multiple precisely etched sub-apertures). Our Fresnel arrays are such diffractive focusers, they offer weight, price and size advantages over traditional optics in space-based astronomical instruments. This novel approach requires only void apertures of special shapes in an opaque material to form sharp images, thus avoiding the wavefront distortion, diffusion and spectral absorption associated with traditional optical media. In our setup, lenses and/or mirrors are involved only downstream (at small sizes) for focal instrumentation and chromatic correction. Fresnel arrays produce high contrast images, the resolution of which reaches the theoretical limit of diffraction. Unlike mirrors, they do not require high precision polishing or positioning, and can be used in a large domain of wavelengths from far IR to far UV, enabling the study of many science cases in astrophysics from exoplanet

  20. Intermediate Strength Gravitational Lensing

    SciTech Connect

    Irwin, John

    2005-03-17

    Weak lensing is found in the correlations of shear in {approx}10{sup 4} galaxy images, strong lensing is detected by the obvious distortion of a single galaxy image, whereas intermediate lensing requires detection of less obvious curvature in several neighboring galaxies. Small impact-parameter lensing causes a sextupole distortion whose orientation is correlated with the quadrupole distortion (shear). By looking within a field for the spatial correlation of this sextupole-quadrupole correlation, an intermediate lensing regime is observed. This technique requires correction for the sextupole as well as the quadrupole content of the PSF. We remove the HST PSF and uncover intermediate lensing in the Hubble deep fields. Correlations of the type expected are found.

  1. Fresnel diffraction of aperture with rough edge

    NASA Astrophysics Data System (ADS)

    Cui, Yuwei; Zhang, Wei; Wang, Junhong; Zhang, Meina; Teng, Shuyun

    2015-06-01

    The Fresnel diffraction of an aperture with a rough edge is studied in this paper. Circular and elliptical apertures with sinusoidal and random edges are chosen as examples to investigate the influence of the aperture edge on the diffraction. The numerical calculation results indicate intuitively the variations of the transverse and longitude diffraction intensity distributions with the edge parameters of the aperture. The data files of aperture models are obtained through the numerical calculations, and the aperture samples are obtained with the help of a liquid crystal light modulator (LCLM). Thus, the practical experiments of the diffractions of apertures with rough edges are carried out. The measured results are consistent with the calculated ones. The approximate analytic expressions of the diffraction by the modified aperture are deduced on the basis of the Fresnel diffraction theory and the statistic optics, and the reasonable explanations for the influence of edge parameters on the diffraction are given through the theoretical analysis.

  2. 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.

  3. Contact Lenses for Vision Correction

    MedlinePlus

    ... Contact Lenses Colored Contact Lenses Contact Lenses for Vision Correction Written by: Kierstan Boyd Reviewed by: Brenda ... on the surface of the eye. They correct vision like eyeglasses do and are safe when used ...

  4. Effect of Mn Addition on Microstructural Modification and Cracking Behavior of Ferritic Light-Weight Steels

    NASA Astrophysics Data System (ADS)

    Sohn, Seok Su; Lee, Byeong-Joo; Lee, Sunghak; Kwak, Jai-Hyun

    2014-11-01

    In the present study, effects of Mn addition on cracking phenomenon occurring during cold rolling of ferritic light-weight steels were clarified in relation to microstructural modification involving κ-carbide, austenite, and martensite. Four steels were fabricated by varying Mn contents of 3 to 12 wt pct, and edge areas of steel sheets containing 6 to 9 wt pct Mn were cracked during the cold rolling. The steels were basically composed of ferrite and austenite in a band shape, but a considerable amount of κ-carbide or martensite existed in the steels containing 3 to 6 wt pct Mn. Microstructural observation of the deformed region of fractured tensile specimens revealed that cracks which were initiated at ferrite/martensite interfacial κ-carbides readily propagated along ferrite/martensite interfaces or into martensite areas in the steel containing 6 wt pct Mn, thereby leading to the center or edge cracking during the cold rolling. In the steel containing 9 wt pct Mn, edge cracks were found in the final stage of cold rolling because of the formation of martensite by the strain-induced austenite to martensite transformation, whereas they were hardly formed in the steel containing 12 wt pct Mn. To prevent or minimize the cracking, it was recommended that the formation of martensite during the cooling from the hot rolling temperature or during the cold rolling should be suppressed, which could be achieved by the enhancement of thermal or mechanical stability of austenite with decreasing austenite grain size or increasing contents of austenite stabilizers.

  5. 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.

  6. myKaryoView: a light-weight client for visualization of genomic data.

    PubMed

    Jimenez, Rafael C; Salazar, Gustavo A; Gel, Bernat; Dopazo, Joaquin; Mulder, Nicola; Corpas, Manuel

    2011-01-01

    The Distributed Annotation System (DAS) is a protocol for easy sharing and integration of biological annotations. In order to visualize feature annotations in a genomic context a client is required. Here we present myKaryoView, a simple light-weight DAS tool for visualization of genomic annotation. myKaryoView has been specifically configured to help analyse data derived from personal genomics, although it can also be used as a generic genome browser visualization. Several well-known data sources are provided to facilitate comparison of known genes and normal variation regions. The navigation experience is enhanced by simultaneous rendering of different levels of detail across chromosomes. A simple interface is provided to allow searches for any SNP, gene or chromosomal region. User-defined DAS data sources may also be added when querying the system. We demonstrate myKaryoView capabilities for adding user-defined sources with a set of genetic profiles of family-related individuals downloaded directly from 23andMe. myKaryoView is a web tool for visualization of genomic data specifically designed for direct-to-consumer genomic data that uses publicly available data distributed throughout the Internet. It does not require data to be held locally and it is capable of rendering any feature as long as it conforms to DAS specifications. Configuration and addition of sources to myKaryoView can be done through the interface. Here we show a proof of principle of myKaryoView's ability to display personal genomics data with 23andMe genome data sources. The tool is available at: http://mykaryoview.com. PMID:22046276

  7. River scale model of a training wall with a light weighted moveable bed

    NASA Astrophysics Data System (ADS)

    Boersema, M.; Hoitink, A.

    2011-12-01

    In order to manage the expected extremity in high and low water levels in the River Rhine, the state authority Rijkswaterstaat in the Netherlands is searching for an alternative river design. Currently the banks on both sides of the River Rhine are protected by groynes. Besides bank protection, the groynes keep the cross-section of the river relatively narrow to ensure water depth for navigation. When the discharge is high, however, the groynes are flooded, which causes an increase in hydraulic roughness and increase in water level. One possibility to ensure the navigation depth during low discharge and reduce the hydraulic roughness during a high discharges is the replacement of the groynes by a training (figure 1). Between the training wall and the bank a new channel is created and the inflow is regulated by a fixed weir, so only a limited discharge will flow through the side channel during a low flow situation. During a flood large amount of water can discharge trough the side channel. An uncertainty in the new dam design comes from the behaviour of the river bed morphology during low and high flow. In order to test the unknown morphological effects at local scale a physical model is build in a flume (figure 2). The scale model is focusing on the intake point of the side channel and on the effect of the river bed levels in the main channel. The model has a mobile bed made of light weighted polystyrene to simulate the bed load transport. In polystyrene, the dunes are developing in equal proportions to dunes in the prototype river. Laser scan results of the bed level show that during low discharge the training wall has a positive effect on the bed levels in navigation channel. The interpretation of the model results and the translation to the prototype is mainly focusing on the spatial pattern of erosion and sedimentation and relative bed levels.

  8. 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…

  9. 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…

  10. 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.

  11. The Orphan Lenses Project

    NASA Astrophysics Data System (ADS)

    Moustakas, Leonidas A.; Brownstein, J.; Fadely, R.; Fassnacht, C. D.; Gavazzi, R.; Goodsall, T.; Griffith, R. L.; Keeton, C. R.; Kneib, J. P.; Koekemoer, A.; Koopmans, L. V. E.; Marshall, P. J.; Merten, J.; Metcalf, R. B.; Oguri, M.; Papovich, C.; Rein, H.; Ryan, R.; Stewart, K. R.; Treu, T.

    2012-01-01

    Strong gravitational lenses are uniquely suited for the study of dark matter structure and substructure within massive halos of many scales, act as gravitational telescopes for distant faint objects, and can give powerful and competitive cosmological constraints. Some 300 lenses have been identified in the literature in one form or another; many others have been found, but perhaps have not warranted dedicated publications. The Orphan Lenses project aims to be a master compilation of all strong gravitational lenses that are known, and a community repository for candidate lenses. A clear and uniform database of basic properties and gravitational lens models is being developed, which will be available online and through a smartphone interactive application. I will present the project, and scientific highlights with this dataset.

  12. 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.

  13. Next Generation X-Ray Optics: High-Resolution, Light-Weight, and Low-Cost

    NASA Technical Reports Server (NTRS)

    Zhang, William W.

    2011-01-01

    X-ray telescopes are essential to the future of x-ray astronomy. This paper describes a comprehensive program to advance the technology for x-ray telescopes well beyond the state of the art represented by the three currently operating missions: Chandra, XMM-Newton , and Suzaku . This program will address the three key issues in making an x-ray telescope: (I) angular resolution, (2) effective area per unit mass, and (3) cost per unit effective area. The objectives of this technology program are (1) in the near term, to enable Explorer-class x-ray missions and an IXO type mission, and (2) in the long term, to enable a flagship x-ray mission with sub-arcsecond angular resolution and multi-square-meter effective area, at an affordable cost. We pursue two approaches concurrently, emphasizing the first approach in the near term (2-5 years) and the second in the long term (4-10 years). The first approach is precision slumping of borosilicate glass sheets. By design and choice at the outset, this technique makes lightweight and low-cost mirrors. The development program will continue to improve angular resolution, to enable the production of 5-arcsecond x-ray telescopes, to support Explorer-class missions and one or more missions to supersede the original IXO mission. The second approach is precision polishing and light-weighting of single-crystal silicon mirrors. This approach benefits from two recent commercial developments: (1) the inexpensive and abundant availability of large blocks of mono crystalline silicon, and (2) revolutionary advances in deterministic, precision polishing of mirrors. By design and choice at the outset, this technique is capable of producing lightweight mirrors with sub-arcsecond angular resolution. The development program will increase the efficiency and reduce the cost of the polishing and the lightweighting processes, to enable the production of lightweight sub-arcsecond x-ray telescopes. Concurrent with the fabrication of lightweight mirror

  14. A Light-Weight Inflatable Hypersonic Drag Device for Planetary Entry

    NASA Technical Reports Server (NTRS)

    McRonald, Angus D.

    1995-01-01

    The author has analyzed the use of a light-weight inflatable hypersonic drag device, called a ballute, (balloon + parachute) for flight in planetary atmospheres, for entry, aerocapture, and aerobraking. Studies to date include missions to Mars, Venus, Earth, Saturn, Titan, Neptune and Pluto. Data on a Pluto lander and a Mars orbiter will be presented to illustrate the concept. The main advantage of using a ballute is that aero deceleration and heating in atmospheric entry occurs at much smaller atmospheric density with a ballute than without it. For example, if a ballute has a diameter 10 times as large as the spacecraft, for unchanged total mass, entry speed and entry angle,the atmospheric density at peak convective heating is reduced by a factor of 100, reducing the peak heating by a factor of 10 for the spacecraft, and a factor of about 30 for the ballute. Consequently the entry payload (lander, orbiter, etc) is subject to much less heating, requires a much reduced thermal protection system (possibly only an MLI blanket), and the spacecraft design is therefore relatively unchanged from its vacuum counterpart. The heat flux on the ballute is small enough to be radiated at temperatures below 800 K or so. Also, the heating may be reduced further because the ballute enters at a more shallow angle, even allowing for the increased delivery angle error. Added advantages are a smaller mass ratio of entry system to total entry mass, and freedom from the low-density and transonic instability problems that conventional rigid entry bodies suffer, since the vehicle attitude is determined by the ballute, usually released at continuum conditions (hypersonic for an orbiter, and subsonic for a lander). Also, for a lander the range from entry to touchdown is less, offering a smaller footprint. The ballute derives an entry corridor for aerocapture by entering on a path that would lead to landing, and releasing the ballute adaptively, responding to measured deceleration, at a speed

  15. Pulsed photothermal deflection and diffraction effects: numerical modeling based on Fresnel diffraction theory

    NASA Astrophysics Data System (ADS)

    Han, Yue; Wu, Z. L.; Rosenshein, Joseph S.; Thomsen, Marshall; Zhao, Qiang; Moncur, Kent

    1999-12-01

    We present a comprehensive theoretical model suitable for treating the effect of pulsed collinear photothermal deflection spectroscopy (PDS). The work is an extension of the theoretical model previously developed for the mirage effect, which can take into account both photothermal deflection and photothermal diffraction effects based on the Fresnel diffraction theory. With the diffraction model, both the collinear PDS and the photothermal lensing spectroscopy techniques can be treated in a unified manner. The model provides a detailed analysis of the laser-induced optical diffraction effect and can be used to optimize experimental parameters. The modeled results are presented in detail, with an emphasis on the advantages of using a near-field detection scheme for achieving the best sensitivity to local temperature change and better experimental stability against environmental noise.

  16. 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.

  17. 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.

  18. 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.

  19. Overall evaluation light-weight composite pressure vessel with alloy liner by acoustic emission and Bragg grating

    NASA Astrophysics Data System (ADS)

    Zhao, Jun-qing; He, Xiao-dong; Wang, Rong-guo; Liu, Wen-bo

    2013-04-01

    Light-weight carbon fiber composite pressure vessel with inner thin-wall aluminum alloy liner has main problem of local buckling during manufacture and working process. The approach of acoustic emission and Bragg grating are adapted to monitoring the light-weight composite vessel under water pressure. Two channels of acoustic emission (AE) were bonded to front dome and cylinder to monitoring the performance of the vessel withstanding maximum 4.5MPa water pressure during loading, maintaining and unloading. Meantime six fiber Bragg sensors (FBG)were attached to front dome and cylinder of the outer surface by hoop and meridian direction respectively in order to monitor the vessel behavior. Analysis indicated Bragg sensors can evaluate outer surface behavior of the vessel with pressure. AE character parameters analysis illustrated the local buckling of inner thin-wall liner.

  20. Vertically-aligned carbon nanotubes on aluminum as a light-weight positive electrode for lithium-polysulfide batteries.

    PubMed

    Liatard, S; Benhamouda, K; Fournier, A; Ramos, R; Barchasz, C; Dijon, J

    2015-05-01

    A light-weight, high specific surface current collector made of vertically-aligned carbon nanotubes grown on an aluminum substrate was fabricated and studied as a positive electrode in a semi-liquid lithium/polysulfide battery. This simple system delivered stable capacities over 1000 mA h gS(-1) and 2 mA h cm(-2) with almost no capacity loss over 50 cycles. PMID:25853546

  1. 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.

  2. 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…

  3. Compact and Light-Weight Automated Semen Analysis Platform Using Lensfree on-Chip Microscopy

    PubMed Central

    Su, Ting-Wei; Erlinger, Anthony; Tseng, Derek; Ozcan, Aydogan

    2010-01-01

    We demonstrate a compact and lightweight platform to conduct automated semen analysis using a lensfree on-chip microscope. This holographic on-chip imaging platform weighs ~46 g, measures ~4.2 × 4.2 × 5.8 cm, and does not require any lenses, lasers or other bulky optical components to achieve phase and amplitude imaging of sperms over ~24 mm2 field-of-view with an effective numerical aperture of ~0.2. Using this wide-field lensfree on-chip microscope, semen samples are imaged for ~10 s, capturing a total of ~20 holographic frames. Digital subtraction of these consecutive lens-free frames, followed by appropriate processing of the reconstructed images, enables automated quantification of the count, the speed and the dynamic trajectories of motile sperms, while summation of the same frames permits counting of immotile sperms. Such a compact and lightweight automated semen analysis platform running on a wide-field lensfree on-chip microscope could be especially important for fertility clinics, personal male fertility tests, as well as for field use in veterinary medicine such as in stud farming and animal breeding applications. PMID:20836503

  4. 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

  5. Design and fabrication of a 3m class light weighted mirror blank for the E-ELT M5

    NASA Astrophysics Data System (ADS)

    Jedamzik, Ralf; Seibert, Volker; Thomas, Armin; Westerhoff, Thomas; Müller, Michael; Cayrel, Marc

    2011-09-01

    In the recent past, SCHOTT has demonstrated its ability to manufacture large light weighted ZERODUR® mirror blanks for telescope projects like the GREGOR solar-telescope, for example. In 2010, SCHOTT was commissioned with a study aimed at developing a design for the M5 mirror blank of the ESO E-ELT. The tip and tilt M5 mirror of the European Extremely Large Telescope (E-ELT) requires a demanding approach in light weighting. The approximately 3.1 m x 2.5 m elliptical plano mirror is specified to a weight of less than 500 kg with high Eigenfrequencies and low deformation under different inclination angles. The study was divided into two parts. The first part focused on coming up with an optimized light weighted design with respect to performance and processability with finite element modeling. In the second part of the study, a concept for the processing sequence including melting, cold-processing, acid etching and handling of the M5 blank was developed. By producing a prototype section, SCHOTT demonstrated its ability to manufacture the demanding features, including pockets 350 mm in depth, thin walls and sloped pocket bottoms. This paper outlines the results of the design work, processing concept and demonstrator fabrication.

  6. 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.

  7. 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.

  8. A Light-Weight Inflatable Hypersonic Drag Device for Planetary Entry

    NASA Technical Reports Server (NTRS)

    McRonald, Angus D.

    2000-01-01

    The author has analyzed the use of a light-weight inflatable hypersonic drag device, called a ballute, for flight in planetary atmospheres, for entry, aerocapture, and aerobraking. Studies to date include Mars, Venus, Earth, Saturn, Titan, Neptune and Pluto, and data on a Pluto lander and a Mars orbiter will be presented to illustrate the concept. The main advantage of using a ballute is that aero, deceleration and heating in atmospheric entry occurs at much smaller atmospheric density with a ballute than without it. For example, if a ballute has a diameter 10 times as large as the spacecraft, for unchanged total mass, entry speed and entry angle,the atmospheric density at peak convective heating is reduced by a factor of 100, reducing the heating by a factor of 10 for the spacecraft and a factor of 30 for the ballute. Consequently the entry payload (lander, orbiter, etc) is subject to much less heating, requires a much reduced thermal. protection system (possibly only an MLI blanket), and the spacecraft design is therefore relatively unchanged from its vacuum counterpart. The heat flux on the ballute is small enough to be radiated at temperatures below 800 K or so. Also, the heating may be reduced further because the ballute enters at a more shallow angle, even allowing for the increased delivery angle error. Added advantages are less mass ratio of entry system to total entry mass, and freedom from the low-density and transonic instability problems that conventional rigid entry bodies suffer, since the vehicle attitude is determined by the ballute, usually released at continuum conditions (hypersonic for an orbiter, and subsonic for a lander). Also, for a lander the range from entry to touchdown is less, offering a smaller footprint. The ballute derives an entry corridor for aerocapture by entering on a path that would lead to landing, and releasing the ballute adaptively, responding to measured deceleration, at a speed computed to achieve the desired orbiter exit

  9. [Phakic intraocular lenses].

    PubMed

    Kohnen, T; Shajari, M

    2016-06-01

    Refractive surgical procedures are generally divided into additive procedures with, e. g. implantation of an artificial lens and subtractive procedures with ablation of corneal tissue. In this article the current status of phakic intraocular lens (IOL) implantation for correction of refractive errors is reviewed. Phakic IOLs are constructed as angle-supported or iris-fixated anterior chamber lenses and sulcus-fixated posterior chamber lenses. The implantation of phakic IOLs has been demonstrated to be an effective, safe, predictable and stable procedure to correct higher refractive errors. Complications are rare and depend to a large extent on the location. For anterior chamber lenses the main concern is critical endothelial cell loss and for posterior chamber lenses early cataract formation. PMID:27277751

  10. 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

  11. 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.

  12. 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.

  13. 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. PMID:20588569

  14. 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. PMID:20607883

  15. 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.

  16. CMB Lensing Cross Correlations

    NASA Astrophysics Data System (ADS)

    Bleem, Lindsey

    2014-03-01

    A new generation of experiments designed to conduct high-resolution, low-noise observations of the Cosmic Microwave Background (CMB)--including ACTpol, Planck, POLARBEAR and SPTpol--are producing exquisite measurements of the gravitational lensing of the CMB. Such measurements, covering large fractions of the sky, provide detailed maps of the projected mass distribution extending to the surface of the CMB's last scattering. Concurrently, a large number of deep, wide-area imaging and spectroscopic surveys (e.g., the Dark Energy Survey (DES),WISE all-sky survey, Subaru HyperSuprimeCam Survey, LSST, MS-DESI, BigBoss, etc.) are, or will soon be, providing maps of the distribution of galaxies in the Universe. Correlations of such tracer populations with lensing data allows new probes of where and how galaxies form in the dark matter skeleton of the Universe. Recent correlations of maps of galaxy and quasar densities with lensing convergence maps have produced significant measurements of galaxy bias. The near-term prospect for improvements in such measurements is notable as more precise lensing data from CMB polarization experiments will help to break cosmological and astrophysical parameter degeneracies. Work by the Planck, SPT, and POLARBEAR collaborations has also focused on the correlation of the Cosmic Infrared Background (CIB) with CMB lensing convergence maps. This correlation is particularly strong as the redshifts of the CIB and CMB lensing kernel are well matched. Such correlations probe high-redshift structure, constraining models of star-formation and the characteristic mass scale for halos hosting CIB galaxies and have also been used to demonstrate the first detection of CMB B-mode polarization--an important milestone in CMB observations. Finally, combining galaxy number density, cosmic shear and CMB lensing maps has the potential to provide valuable systematic tests for upcoming cosmological results from large optical surveys such as LSST.

  17. Novel optical scanning cryptography using Fresnel telescope imaging.

    PubMed

    Yan, Aimin; Sun, Jianfeng; Hu, Zhijuan; Zhang, Jingtao; Liu, Liren

    2015-07-13

    We propose a new method called modified optical scanning cryptography using Fresnel telescope imaging technique for encryption and decryption of remote objects. An image or object can be optically encrypted on the fly by Fresnel telescope scanning system together with an encryption key. For image decryption, the encrypted signals are received and processed with an optical coherent heterodyne detection system. The proposed method has strong performance through use of secure Fresnel telescope scanning with orthogonal polarized beams and efficient all-optical information processing. The validity of the proposed method is demonstrated by numerical simulations and experimental results. PMID:26191901

  18. Fresnel mirrors heliostat optimization through altazimuthal mounting

    NASA Astrophysics Data System (ADS)

    Chaput, E.; Arnaud, G.

    1984-04-01

    A numerical model is defined for optimizing the altazimuthal tracking performance of multi-faceted heliostats focusing on a power tower. The THEMIS tower was taken as the reference figure. Calculations were confined to heliostats at least 250 m from the tower, where the image usually becomes the most distorted. Attention was given to the mirror facets at the extremities and at the center of the heliostat. Comparisons were made between the performances of a spherical heliostat and a facetted one, the latter having individually adjustable mirrored components. It is shown that the solar image projected on the tower boiler can be made more stable at a wider diversity of solar angles if the multifacetted Fresnel lens concept is applied to the design of spherical heliostats.

  19. Aerosol lenses propagation model.

    PubMed

    Tremblay, Grégoire; Roy, Gilles

    2011-09-01

    We propose a model based on the properties of cascading lenses modulation transfer function (MTF) to reproduce the irradiance of a screen illuminated through a dense aerosol cloud. In this model, the aerosol cloud is broken into multiple thin layers considered as individual lenses. The screen irradiance generated by these individual layers is equivalent to the point-spread function (PSF) of each aerosol lens. Taking the Fourier transform of the PSF as a MTF, we cascade the lenses MTF to find the cloud MTF. The screen irradiance is found with the Fourier transform of this MTF. We show the derivation of the model and we compare the results with the Undique Monte Carlo simulator for four aerosols at three optical depths. The model is in agreement with the Monte Carlo for all the cases tested. PMID:21886230

  20. 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).

  1. 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.

  2. 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.

  3. 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. PMID:20607886

  4. 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. PMID:20588574

  5. Fast laser optical CT scanner with rotating mirror and Fresnel lenses

    NASA Astrophysics Data System (ADS)

    Conklin, J.; Deshpande, R.; Battista, J.; Jordan, K.

    2006-12-01

    Single laser beam and detector computed tomography (CT) scanner geometries provide excellent stray light rejection and these systems likely provide the largest dynamic range for optical CT scanning of gel dosimeters. In this work a rotating mirror, lens pair, laser scanner has been developed for a 10 x 15 cm2 field of view demonstrating a fast 3D single ray-detector optical CT scanner.

  6. 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. PMID:27553528

  7. 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.

  8. 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%.

  9. Weak lensing corrections to tSZ-lensing cross correlation

    NASA Astrophysics Data System (ADS)

    Tröster, Tilman; Van Waerbeke, Ludovic

    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 gtrsim 3000.

  10. Static and Dynamic Analysis of Stretched Membrane Lenses for Lightweight Space Solar Arrays

    NASA Astrophysics Data System (ADS)

    Mockensturm, Eric M.

    2002-12-01

    NASA and ENTECH, Inc. have been developing space photovoltaic arrays using refractive concentrator technology since 1986. These refractive concentrators use Fresnel lenses in a unique arch shape to minimize the effects of shape errors. In 1994, silicone Fresnel lenses where used in the SCARLET(Registered Trademark) solar array developed by ENTECH and AEC-ABLE. In this array the 200-micron-thick lenses were laminated to 75-micron-thick, thermally shaped, ceria-doped glass arches. These glass arches forced the flexible lenses into the optimal arch shape. The arrays constructed using these lenses achieved over 200 W/sq m areal power and 45 W/kg specific power and are currently powering both the spacecraft and the ion engine on the NASA/JPL Deep Space One probe. To further reduce weight and increase areal and specific power, the next generation of solar concentrator arrays will eliminate the glass arch and lens frame. The flexible lenses will be stretched as membranes between optimally shaped, supporting end arches. This patented stretched lens array will also use redesigned composite radiator sheets to reduce the weight of the SCARLET panels by a factor of four. In addition, by eliminating optical losses caused by the glass arches and lens frames, the SLA performance is higher than SCARLET. The SLA is the first solar array panel of any kind to simultaneously achieve over 300 W/sq m areal power and 300 W/kg specific power. While the optical properties of the stretched lenses are excellent, they must be analyzed structurally to ensure that they perform at their optimal levels. Lens parameters such as backing thickness, lens tension, and effective length can be altered to change the structural response of the lens without affecting the optical performance. In particular, the lenses must be designed to maintain the arch shape specified by the end support along the entire length. Because the lenses are flat in their natural state, they resist being bent into the desired

  11. Rainwater lenses in wetlands

    NASA Astrophysics Data System (ADS)

    Dekker, S. C.; Schot, P. P.; Bootsma, M. C.

    2003-04-01

    In the Netherlands, drainage and groundwater abstraction in wetlands has lead to deterioration of fen vegetation through lowering of the phreatic level. This enables recharge of local, acid precipitation and the development of rainwater lenses which float on alkaline groundwater. These lenses prevent upward seeping of the groundwater reaching the fen root zone. In the nature reserve Ilperveld (The Netherlands), a ditch/trench system was dug for the purpose of creating run-off for acid rainwater in wet periods, and to enable neutral surface water in dry periods. Sods were removed to decrease the evapotranspiration. Knowledge of the form and behaviour of rainwater lenses in the root zone of wetlands is a prerequisite in fen restoration projects in order to design effective and cost-efficient measures. With a saturated-unsaturated solute transport model (HYDRUS-2D), numerical simulations were performed. Model results are compared with temporal and spatial measurements of electrical conductivity measured in the Ilperveld. Furthermore, results of temporal dynamics of rainwater lenses are shown as function of (i) the phreatic level, (ii) the number of drainage canals and (iii) the groundwater inflow fluxes.

  12. Weak Lensing with LSST

    NASA Astrophysics Data System (ADS)

    Wittman, David M.; Jain, B.; Jarvis, M.; Knox, L.; Margoniner, V.; Takada, M.; Tyson, J.; Zhan, H.; LSST Weak Lensing Science Collaboration

    2006-12-01

    Constraining dark energy parameters with weak lensing is one of the primary science goals of the LSST. The LSST Weak Lensing Science Collaboration has been formed with the goal of optimizing the weak lensing science by optimizing the survey cadence; working with Data Management to insure high-quality pipeline processing which will meet our needs; developing the necessary analysis tools well before the onset of data-taking; participating in high-fidelity simulations to test the system end-to-end; and analyzing the real dataset as it becomes available. We review the major weak lensing probes, the twoand three-point shear correlations, and how they constrain dark energy parameters. We also review the possibility of going beyond dark energy models and testing gravity with the LSST data. To realize the promise of the awesome LSST statistical precision, we must ensure that systematic errors are kept under control. We review the major sources of systematics and our plans for mitigation. We present data that demonstrate that these sources of systematics can be kept to a level smaller than the statistical error.

  13. 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

  14. A modified Fresnel scattering model for the parameterization of Fresnel returns, part 2.3A

    NASA Technical Reports Server (NTRS)

    Gage, K. S.; Ecklund, W. L.; Balsley, B. B.

    1984-01-01

    A modified Fresnel scatter model is presented and the revised model is compared with observations from the Poker Flat, Alaska, radar, the SOUSY radar and the Jimcamarca radar. The modifications to the original model have been made to better account for the pulse width dependence and height dependence of backscattered power observed at vertical incidence at lower VHF. Vertical profiles of backscattered power calculated using the revised model and routine radiosonde data show good agreement with observed backscattered power profiles. Relative comparisons of backscattered power using climatological data for the model agree fairly well with observed backscattered power profiles from Poker Flat, Jicamarca, and SOUSY.

  15. Development and application of a light-weight, wind-turbine rotor-based data acquisition system

    SciTech Connect

    Berg, D.E.; Robertson, P.J.; Ortiz, M.F.

    1998-04-01

    Wind-energy researchers at the National Wind Technology Center (NWTC), representing Sandia National Laboratories (SNL) and the National Renewable Energy Laboratory (NREL), are developing a new, light-weight, modular data acquisition unit capable of acquiring long-term, continuous time-series data from small and/or dynamic wind-turbine rotors. The unit utilizes commercial data acquisition hardware, spread-spectrum radio modems, and Global Positioning System receivers, and a custom-built programmable logic device. A prototype of the system is now operational, and initial field deployment is expected this summer. This paper describes the major subsystems comprising the unit, summarizes the current status of the system, and presents the current plans for near-term development of hardware and software.

  16. 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. PMID:21743581

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. Harmonic diffractive lenses

    SciTech Connect

    Sweeney, D.W.; Sommargren, G.E.

    1995-05-10

    The harmonic diffractive lens is a diffractive imaging lens for which the optical path-length transition between adjacent facets is an integer multiple {ital m} of the design wavelength {lambda}{sub 0}. The total lens thickness in air is {ital m}{lambda}{sub 0}/({ital n} {minus} 1), which is {ital m} times thicker than the so-called modulo 2{pi} diffractive lens. Lenses constructed in this way have hybrid properties of both refractive and diffractive lenses. Such a lens will have a diffraction-limited, common focus for a number of discrete wavelengths across the visible spectrum. A 34.75-diopter, 6-mm-diameter lens is diamond turned in aluminum and replicated in optical materials. The sag of the lens is 23 {mu}m. Modulation transfer function measurements in both monochromatic and white light verify the performance of the lens. The lens approaches the diffraction limit for 10 discrete wavelengths across the visible spectrum.

  2. Tolerances in panoramic lenses

    NASA Astrophysics Data System (ADS)

    Thibault, Simon; Dallaire, Xavier

    2014-09-01

    Almost every aspect concerning the optical design of panoramic lenses brings new challenges to optical designers. Examples of these include ray tracing programs having problems finding the entrance pupil which is moving through the field-of-view, optimization, production particularities due to the shape of the lenses, and ways of tolerancing these systems having strong distortion. This last topic will be discussed in this paper. We will start from a historical perspective on the understanding of panoramic imagery. This will lead us to the modern panoramic imager called the Panomorph lens. We will discuss the particular case of the tolerance of the front surface (most of the time a freeform surface) and the impact on the image quality, both image footprint and field curvature. We will explain the behavior using first and second order approaches.

  3. 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.

  4. 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.

  5. 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.

  6. 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. PMID:27557260

  7. 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.

  8. 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. PMID:27137315

  9. 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.

  10. Physical approach to analytic simulation of Fresnel integrals

    NASA Astrophysics Data System (ADS)

    Anokhov, Sergey

    2007-01-01

    Fresnel integrals continue to find new applications in various areas of human activity, including technology and music. However, performing calculations with them is often hindered by a mathematical peculiarity of these integrals, which is the rapidly oscillating functions of the basic variable. This circumstance complicates the numerical calculations when these integrals need additional integral transformation: convolution, Fourier transform, etc. The suggested solution of the problem consists of replacement of the complex Fresnel integral by a single rational function that simulates this integral in the entire area of its existence with an accuracy up to 10-6. The advantages of the suggested approach are confirmed by the concrete example.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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. PMID:26357328

  16. 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

    2016-01-01

    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. PMID:27533875

  17. 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. PMID:24515148

  18. 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.

  19. High resolution Fresnel zone plate laser alignment system

    SciTech Connect

    Bressler, V.E.; Fischer, G.E.; Ruland, R.E.; Wang, T.

    1992-03-01

    The existing Fresnel zone plate laser alignment system is currently being extended and upgraded for the Final Focus Test Beam (FFTB). Previously, the resolution of this system has been several tens of micrometers. After the upgrade, the resolution will be a few micrometers. Details of the upgrade as well as simulation and experimental results will be presented.

  20. The dome-shaped Fresnel-Köhler concentrator

    NASA Astrophysics Data System (ADS)

    Zamora, P.; Benitez, P.; Li, Y.; Miñano, J. C.; Mendes-Lopes, J.; Araki, K.

    2012-10-01

    Manufacturing tolerances, along with a high concentration ratio, are key issues in order to obtain cheap CPV systems for mass production. Consequently, this manuscript presents a novel tolerant and cost effective concentrator optic: the domed-shaped Fresnel-Köhler, presenting a curved Fresnel lens as Primary Optical Element (POE). This concentrator is based on two previous successful CPV designs: the FK concentrator, based on a flat Fresnel lens, and the dome-shaped Fresnel lens system developed by Daido Steel, resulting on a superior concentrator. The manuscript shows outstanding simulation results for geometrical concentration factor of Cg = 1,230x: high tolerance and high optical efficiency, achieving acceptance angles of 1.18° (dealing to a CAP*=0.72) and efficiencies over 85% (without any anti-reflective coating). Moreover, Köhler integration provides good irradiance uniformity on the cell surface without increasing system complexity by means of any extra element. Daido Steel advanced technique for demolding injected plastic pieces will allow for easy manufacture of the dome-shaped POE of DFK concentrator.

  1. 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.

  2. 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. PMID:3826294

  3. A liquid crystal and polymer composite film for liquid crystal lenses

    NASA Astrophysics Data System (ADS)

    Lin, Yi-Hsin; Chen, Hung-Shan; Wang, Yu-Jen; Chang, Chia-Ming

    2015-03-01

    Liquid crystal (LC) lenses offer novel opportunities for applications of ophthalmic lenses, camera modules, pico projectors, endoscopes, and optical zoom systems owing to electrically tunable lens power. Nevertheless, the tunable lens power and the aperture size of LC lenses are limited by the optical phase resulting from limit birefringence of LC materials. Recently, we developed a liquid crystal and polymer composite film (LCPCF) as a separation layer and an alignment layer for a multi-layered structure of LC lenses in order to enlarge the polarization-independent optical phase modulation. However, the physical properties and mechanical properties of the LCPCF are not clearly investigated. In this paper, we show the mechanical and physical properties of the LCPCF. The anchoring energy of the LCPCF is comparable with the standard rubbing-induced alignment layer. The transmission efficiency is around 97% neglecting the Fresnel reflection. The surface roughness is under 2 nm by using AFM scanning. The bending strength test indicates that the LCPCF can hold the LC material with reasonable deformation. We believe this study provides a deeper insight to the LC lens structure embedded with LCPCF.

  4. 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.

  5. 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

    2016-09-01

    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 optimisation 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 SLACS 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.

  6. 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.

  7. 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.

  8. Wave bottom boundary layer processes below irregular surfzone breaking waves with light-weight sheet flow particle transport

    NASA Astrophysics Data System (ADS)

    Chassagneux, François Xavier; Hurther, David

    2014-03-01

    The present work investigates the structure of the near-bed flow below irregular surfzone breaking waves inducing light-weight sheet flow particle transport. The experiments are carried out in the LEGI flume under steady equilibrium conditions between the wave forcing and the underlying bed morphology. Synchronized ACVP and video images provide detailed information about the mean wave and current characteristics and the coupled flow regimes across the entire wave breaking region including the outer and the inner surfzones. An analysis of the impact of breaking eddies in the Wave Boundary Layer (WBL) is undertaken at the beginning of the inner surfzone. Subsequently, the intrawave variation of several contributions of the total shearing force per unit area and the net values of the Reynolds stress related to phase-averaged velocities are analyzed. It is found that -ρu˜w˜ is the dominant term. The turbulent Reynolds stress, the low frequency, and the mean terms are at least 1 order of magnitude lower. Due to the irregular wave forcing, the net values are separated into the net wave-by-wave Reynolds stress and the wave Reynolds stress averaged over the entire irregular wave sequence. All these measured bed shear stress terms are then compared to estimations obtained with two different parameterized models in order to evaluate their prediction performances. The values of the model parameters are discussed in comparison to those found in the literature. Finally, the vertical profile of net Reynolds shear stress exhibits a nearly constant value across the sheet-flow layer.

  9. Fabrication of Compound Refractive X-ray Lenses Using LIGA Process and Performance Tests

    SciTech Connect

    Lee, Jin Pyoung; Kim, Guk Bae; Kim, Jong Hyun; Chang, Suk Sang; Lee, Sang Joon

    2007-01-19

    Recent advances of X-ray microscopy technology enable the visualization of some micro/nano-scale objects which optical microscopy and electron microscopy cannot be used to observe. The X-ray microscopy can be applied to observe the internal structure of a thicker sample than the electron microscopy can, and its spatial resolution is higher than that of the optical microscopy. Moreover, it has a powerful element specific imaging ability. For further improving the X-ray microscope, it is indispensable to make X-ray optics for focusing X-rays more effectively. Recently, various X-ray lenses such as diffraction lenses of FZP(Fresnel zone plate) and spatter-sliced FZT, total reflection lenses of K-B(Kirkpatrick-Baez) mirror and Wolter mirror, and refractive lens of CRL(compound refractive lens) were introduced. Compared with the other types of lenses, CRL is easy to fabricate and handle. In this study, we designed and fabricated various types of CRLs using LIGA(LIthographie, Galvanoformung, Abformtechnik) process, and used PMMA(Poly(methyl methacrylate)) material as the material of CRL. Their performances are tested with varying parameters such as parabolic/kinoform shape, radius of curvature, wall thickness between adjacent lenses, and width of lenses. The performance tests were carried out by using a simple synchrotron X-ray imaging method. The tests results revealed that hard x-rays could be condensed well by the CRL of PMMA material at the focal point we expect We captured sample images one-dimensionally magnified by CRLs. Furthermore, we found which parameter is more effective for enhancing focus efficiency and which parameter should be considered more carefully in the fabrication process of LIGA.

  10. 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.

  11. Gravitational lensing by gravastars

    NASA Astrophysics Data System (ADS)

    Kubo, Tomohiro; Sakai, Nobuyuki

    2016-04-01

    As a possible method to detect gravastars (gravitational-vacuum-star), which was originally proposed by Mazur and Mottola, we study their gravitational lensing effects. Specifically, we adopt a spherical thin-shell model of a gravastar developed by Visser and Wiltshire, which connects interior de Sitter geometry and exterior Schwarzschild geometry, and assume that its surface is optically transparent. We calculate the image of a companion which rotates around the gravastar; we find that some characteristic images appear, depending on whether the gravastar possess unstable circular orbits of photons (Model 1) or not (Model 2). For Model 2, we calculate the total luminosity change, which is called microlensing effects; the maximal luminosity could be considerably larger than the black hole with the same mass.

  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. Galaxy cluster lensing masses in modified lensing potentials

    DOE PAGESBeta

    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 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

  14. 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.

  15. 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.

  16. 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.

  17. CMB lensing and giant rings

    NASA Astrophysics Data System (ADS)

    Rathaus, Ben; Itzhaki, Nissan

    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.

  18. 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.

  19. 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.

  20. 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

  1. Gravitational lensing in quasar samples

    NASA Astrophysics Data System (ADS)

    Claeskens, Jean-François; Surdej, Jean

    The first cosmic mirage was discovered approximately 20 years ago as the double optical counterpart of a radio source. This phenomenon had been predicted some 70 years earlier as a consequence of General Relativity. We present here a summary of what we have learnt since. The applications are so numerous that we had to concentrate on a few selected aspects of this new field of research. This review is focused on strong gravitational lensing, i.e. the formation of multiple images, in QSO samples. It is intended to give the reader an up-to-date status of the observations and to present an overview of its most interesting potential applications in cosmology and astrophysics, as well as numerous important results achieved so far. The first section follows an intuitive approach to the basics of gravitational lensing and is developed in view of our interest in multiply imaged quasars. The astrophysical and cosmological applications of gravitational lensing are outlined in Sect. 2 and the most important results are presented in Sect. 5. Sections 3 and 4 are devoted to the observations. Finally, conclusions are summarized in the last section. We have tried to avoid duplication with existing (and excellent) introductions to the field of gravitational lensing. For this reason, we did not concentrate on the individual properties of specific lens models, as these are already well presented in Narayan and Bartelmann (1996) and on a more intuitive ground in Refsdal and Surdej (1994). Wambsganss (1998) proposes a broad view on gravitational lensing in astronomy; the reviews by Fort and Mellier (1994) and Hattori et al. (1999) deal with lensing by galaxy clusters; microlensing in the Galaxy and the local group is reviewed by Paczynski (1996) and a general panorama on weak lensing is given by Bartelmann and Schneider (1999) and Mellier (1999). The monograph on the theory of gravitational lensing by Schneider, Ehlers and Falco (1992) also remains a reference in the field.

  2. 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.

  3. Comparative simulations of Fresnel holography methods for atomic waveguides

    NASA Astrophysics Data System (ADS)

    Henderson, V. A.; Griffin, P. F.; Riis, E.; Arnold, A. S.

    2016-02-01

    We have simulated the optical properties of micro-fabricated Fresnel zone plates (FZPs) as an alternative to spatial light modulators for producing non-trivial light potentials to trap atoms within a lensless Fresnel arrangement. We show that binary (1 bit) FZPs with wavelength (1 μm) spatial resolution consistently outperform kinoforms of spatial and phase resolution comparable to commercial SLMs in root mean square error comparisons, with FZP kinoforms demonstrating increasing improvement for complex target intensity distributions. Moreover, as sub-wavelength resolution microfabrication is possible, FZPs provide an exciting possibility for the creation of static cold-atom trapping potentials useful to atomtronics, interferometry, and the study of fundamental physics.

  4. Babinet's principle in the Fresnel regime studied using ultrasound

    NASA Astrophysics Data System (ADS)

    Hitachi, Akira; Takata, Momo

    2010-07-01

    The diffraction of ultrasound by a circular disk and an aperture of the same size has been investigated as a demonstration of Babinet's principle in the Fresnel regime. The amplitude and the phase of the diffracted ultrasonic waves are measured and a graphical treatment of the results is performed by drawing vectors in the complex plane. The results verify Babinet's principle. It is also found that the incident wave is π /2 behind the phase of the wave passing through on the central axis of a circular aperture. Because both waves travel the same path and the same distance, they should be in phase. This paradox has previously been regarded as a defect of Fresnel's theory.

  5. 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. PMID:27464132

  6. Progress on an external occulter testbed at flight Fresnel numbers

    NASA Astrophysics Data System (ADS)

    Kim, Yunjong; Sirbu, Dan; Galvin, Michael; Kasdin, N. Jeremy; Vanderbei, Robert J.

    2016-01-01

    An external occulter is a spacecraft flown along the line-of-sight of a space telescope to suppress starlight and enable high-contrast direct imaging of exoplanets. Laboratory verification of occulter designs is necessary to validate the optical models used to design and predict occulter performance. At Princeton, we have designed and built a testbed that allows verification of scaled occulter designs whose suppressed shadow is mathematically identical to that of space occulters. The occulter testbed uses 78 m optical propagation distance to realize the flight Fresnel numbers. We will use an etched silicon mask as the occulter. The occulter is illuminated by a diverging laser beam to reduce the aberrations from the optics before the occulter. Here, we present first light result of a sample design operating at a flight Fresnel number and the mechanical design of the testbed. We compare the experimental results with simulations that predict the ultimate contrast performance.

  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. 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.

  9. 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

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

    PubMed

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

    2010-12-01

    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. PMID:21164982

  11. 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

  12. Weak lensing and cosmological investigation

    NASA Astrophysics Data System (ADS)

    Acquaviva, Viviana

    2005-03-01

    In the last few years the scientific community has been dealing with the challenging issue of identifying the dark energy component. We regard weak gravitational lensing as a brand new, and extremely important, tool for cosmological investigation in this field. In fact, the features imprinted on the Cosmic Microwave Background radiation by the lensing from the intervening distribution of matter represent a pretty unbiased estimator, and can thus be used for putting constraints on different dark energy models. This is true in particular for the magnetic-type B-modes of CMB polarization, whose unlensed spectrum at large multipoles (l ~= 1000) is very small even in presence of an amount of gravitational waves as large as currently allowed by the experiments: therefore, on these scales the lensing phenomenon is the only responsible for the observed power, and this signal turns out to be a faithful tracer of the dark energy dynamics. We first recall the formal apparatus of the weak lensing in extended theories of gravity, introducing the physical observables suitable to cast the bridge between lensing and cosmology, and then evaluate the amplitude of the expected effect in the particular case of a Non-Minimally-Coupled model, featuring a quadratic coupling between quintessence and Ricci scalar.

  13. 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. PMID:25353576

  14. 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. PMID:16286284

  15. 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.

  16. Design of infrared telephoto lenses for joint transform correlator

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Shang, Ji-yang; Li, Zheng; Wang, Wen-sheng

    2011-08-01

    Infrared optical system has been widely used in many fields, especially in target detection and recognition. While the virtue of infrared optical system is that it can not only detect great distance but also detect the target in the poor conditions such as turbid air or smoke, flog and snow. Hybrid optoelectronic joint transform correlator (HOJTC) is very useful for target detection and recognition. Exploiting the Fourier transform property of a lens, it can implement target detection in real time. Designing perfect optical system is one of key technology of target detection. In this paper, the infrared detector which we adopted is infrared focal plane arrays with working waveband 3-5μm. Its resolving power is 30 lp/mm. For the infrared optical system, the effective focal length, relative aperture and the field of view should be large enough to ensure the long distance and large field of view target can be detected. In hybrid optoelectronic joint transform correlator, the light weight and big aperture of infrared optical system is required. For this purpose, an aspheric surface is introduced and the telephoto lens is composed of the three pieces of lenses. The MTF curve of the telephoto lens is close to diffraction limit. The result shows that the aspheric surface can not only simplify and reduce the structure and weight of the system respectively, but also can effectively improve the image quality of the system. This telephoto lens can be used in HOJTC for infrared target detection.

  17. Transmission of the normal and cataractous lenses.

    PubMed

    Bielski, A; Robaczewski, T; Wolnikowski, J; Bieganowski, L

    1991-01-01

    Results of measurements of the transmission (total and in line) of cataractous lenses are presented. A magnitude is introduced which can be used as a measure of the in vitro opacity of lenses. PMID:1911631

  18. Visual Reliability : The Conception Of Varilux Lenses

    NASA Astrophysics Data System (ADS)

    Lenne, William

    1986-05-01

    There is currently very rapid development of progressive lenses ; indeed, these lenses have been the subject of numerous studies, which show their remarkable aptitude for the correction of presbyopia.

  19. Astrophysical Uses Of Cmb Lensing

    NASA Astrophysics Data System (ADS)

    Das, Sudeep

    2009-01-01

    The future of Cosmic Microwave Background (CMB) research lies in exploiting the arcminute scale secondary anisotropies which encode information about the late time interaction of the CMB photons with the structure in the Universe. A specific form of such interaction is the gravitational lensing of the CMB - the main topic of this thesis. Upcoming experiments like ACT, SPT and PLANCK will measure these anisotropies with unprecedented resolution and sensitivity. In this thesis, we present new techniques to model and analyse such high resolution data and explore the implications of such measurements on Cosmology. First, we describe a novel method for simulating high resolution large sky lensed CMB maps. Maps simulated through this method will be instrumental in developing the detection and analysis techniques for CMB lensing. Second, we describe a new and efficient method for measuring the power spectrum of arcminute resolution CMB maps. At these resolutions, aliasing of power due to hard edges and point source masks become a serious problem. Our method efficiently remedies these problems and the reduces uncertainties in the final power spectrum estimate by several factors over those obtainable by the now standard methods. This technique will be also useful for estimating higher order statistics from the maps, like the ones related to the detection of CMB lensing and its cross-correlation with large scale structure. Next, we exemplify how such cross-correlations can be turned into Cosmological probes. We propose an estimator for cosmological distance ratios based on CMB and galaxy lensing and show that it can be measured to sufficient accuracy in future experiments to be Cosmologically useful. Finally, we show that CMB lensing can be used to constrain the void and the texture hypotheses that have been put forward for explaining the intriguing Cold Spot anomaly in the WMAP data.

  20. Aspheric lenses for terahertz imaging.

    PubMed

    Lo, Yat Hei; Leonhardt, Rainer

    2008-09-29

    We present novel designs for aspheric lenses used in terahertz (THz) imaging. As different surfaces result in different beam shaping properties and in different losses from reflection and absorption, the resultant imaging resolution (i.e. the focal spot size) depends critically on the design approach. We evaluate the different lens designs using Kirchhoff's scalar diffraction theory, and test the predictions experimentally. We also show that our lenses can achieve sub-wavelength resolution. While our lens designs are tested with THz radiation, the design considerations are applicable also to other regions of the electro-magnetic spectrum. PMID:18825237

  1. Terahertz super thin planar lenses

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Ye, Jiasheng; Hu, Dan; Wang, Xinke; Feng, Shengfei; Sun, Wenfeng

    2012-12-01

    Terahertz (THz) radiation is an under developing range in the electromagnetic spectrum. It has attracted a lot of attentions due to its various potential applications. However, THz systems are difficult to be integrated into a smart size due to the limitation of its long wavelength. In this presentation, we propose a new approach to design planar lenses with a thickness of several hundred nanometers in the THz range. The fabricated lenses are characterized with a focal plane imaging system and it is found that they can focus the THz light and image an object well. It is expected that this new approach can pave a way for smart THz systems integration.

  2. 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.

  3. 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.

  4. Digital Model of Fourier and Fresnel Quantized Holograms

    NASA Astrophysics Data System (ADS)

    Boriskevich, Anatoly A.; Erokhovets, Valery K.; Tkachenko, Vadim V.

    Some models schemes of Fourier and Fresnel quantized protective holograms with visual effects are suggested. The condition to arrive at optimum relationship between the quality of reconstructed images, and the coefficient of data reduction about a hologram, and quantity of iterations in the reconstructing hologram process has been estimated through computer model. Higher protection level is achieved by means of greater number both bi-dimensional secret keys (more than 2128) in form of pseudorandom amplitude and phase encoding matrixes, and one-dimensional encoding key parameters for every image of single-layer or superimposed holograms.

  5. 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.

  6. Double random-phase encoding in the Fresnel domain.

    PubMed

    Situ, Guohai; Zhang, Jingjuan

    2004-07-15

    A lensless optical security system based on double random-phase encoding in the Fresnel domain is proposed. This technique can encrypt a primary image to random noise by use of two statistically independent random-phase masks in the input and transform planes, respectively. In this system the positions of the significant planes and the operation wavelength, as well as the phase codes, are used as keys to encrypt and recover the primary image. Therefore higher security is achieved. The sensitivity of the decrypted image to shifting along the propagation direction and to the wavelength are also investigated. PMID:15309826

  7. Tracking high amplitude auto-oscillations with digital Fresnel holograms.

    PubMed

    Picart, Pascal; Leval, Julien; Piquet, Francis; Boileau, Jean P; Guimezanes, Thomas; Dalmont, Jean-Pierre

    2007-06-25

    Method for tracking vibrations with high amplitude of several hundreds of micrometers is presented. It is demonstrated that it is possible to reconstruct a synthetic high amplitude deformation of auto-oscillations encoded with digital Fresnel holograms. The setup is applied to the auto-oscillation of a clarinet reed in a synthetic mouth. Tracking of the vibration is performed by using the pressure signal delivered by the mouth. Experimental results show the four steps of the reed movement and especially emphasize the shocks of the reed on the mouthpiece. PMID:19547155

  8. Tracking high amplitude auto-oscillations with digital Fresnel holograms

    NASA Astrophysics Data System (ADS)

    Picart, Pascal; Leval, Julien; Piquet, Francis; Boileau, Jean P.; Guimezanes, Thomas; Dalmont, Jean-Pierre

    2007-06-01

    Method for tracking vibrations with high amplitude of several hundreds of micrometers is presented. It is demonstrated that it is possible to reconstruct a synthetic high amplitude deformation of auto-oscillations encoded with digital Fresnel holograms. The setup is applied to the auto-oscillation of a clarinet reed in a synthetic mouth. Tracking of the vibration is performed by using the pressure signal delivered by the mouth. Experimental results show the four steps of the reed movement and especially emphasize the shocks of the reed on the mouthpiece.

  9. Analysis of clarinet reed oscillations with digital Fresnel holography

    NASA Astrophysics Data System (ADS)

    Picart, P.; Leval, J.; Piquet, F.; Boileau, J.-P.; Dalmont, J.-P.

    2009-07-01

    This paper describes optical instrumentation devoted to vibration analysis. Two strategies based on digital Fresnel holography are presented. The first, called time-averaging consists in the numerical reconstruction of the hologram after recording with an exposure time much greater than the vibration period. Thus, the holograms are amplitude modulated by a Bessel function. The last strategy, using a pulsed regime, allows the reconstruction of the full movement of the vibration, even if it exhibits very high amplitude. Experimental results presented in this paper concern the study of the vibrations of a clarinet reed under free and forced oscillation regimes.

  10. 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.

  11. 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.

  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. Overview of the multilayer-Fresnel zone plate and the kinoform lens development at MPI for intelligent systems

    NASA Astrophysics Data System (ADS)

    Tunca Sanli, Umut; Keskinbora, Kahraman; Grévent, Corinne; Schütz, Gisela

    2015-05-01

    The ultimate goal of our research is to develop novel fabrication methods for high efficiency and high resolution X-ray optics. To this end, we have been pursuing the fabrication of several innovative diffractive/refractive optics designs. One such optic is the multilayer type Fresnel zone plate (ML-FZP). Our fabrication process relies on the atomic layer deposition (ALD) of two materials on a smooth glass fiber followed by a focused ion beam (FIB) based slicing and polishing. The ALD process allows much smaller outermost zone widths than the standard electron beam lithography based FZPs, meaning FZPs with potentially higher resolutions. Moreover, by depositing the multilayer on a cm long glass-fiber FZPs with very high optical thicknesses can be fabricated that can efficiently focus harder X-rays as well. A 21 nm half-pitch resolution was achieved using the ML-FZPs. Another optic we have been working on is the kinoform lens, which is a refractive/diffractive optic with a 100 % theoretical focusing efficiency. Their fabrication is usually realized by using approximate models which limit their success. Recently the fabrication of real kinoform lenses has been successfully realized in our lab via gray-scale direct-write ion beam lithography without any approximations. The lenses have been tested in the soft X-ray range achieving up to ~90 % of the calculated efficiency which indicates outstanding replication of the designed profile. Here we give an overview of our research and discuss the future challenges and opportunities for these optics.

  14. 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.

  15. Demonstrating and optimizing the dual dispersion and focusing functionality of grating-Fresnel lens

    NASA Astrophysics Data System (ADS)

    Zhou, Qian; Zhang, Jinchao; Ni, Kai; Pang, Jinchao; Tian, Rui

    2014-11-01

    As optical spectroscopy plays a vital role in many of modern science and engineering, there is a growing need for developing an inexpensive and miniature spectrometers. Many attempts have been tried to solve the issue. Grating-Fresnel is a hybrid device that fuses the functions of a grating and Fresnel lens into a single device. In this paper, we try to simulate reflection type and transmission type G-Fresnel device in ZAMAX. And with the aids of ZEMAX, we try to optimize the Fresnel lens, grating pattern. A better alignment for the CCD detector could also improve sensitivity of the system as well. In order to improve the resolution and sensitivity, the length between Fresnel lens and gratings will be optimized.

  16. 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…

  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. [Special intra-ocular lenses].

    PubMed

    Jacobi, K W; Nowak, M R; Strobel, J

    1990-01-01

    Intraocular lens (IOL) implantation is the method established worldwide for visual rehabilitation following cataract surgery. IOL's with particular characteristics and/or for special purposes are available for clinical or experimental use. Bifocal and multifocal IOLs have two or more foci for simultaneous far and near vision. The first clinical results are promising. The theoretically expected disadvantages, i.e., reduced contrast sensitivity or reduced visual acuity under reduced contrast conditions, have not yet been found in clinical studies. In cases of age-related macular degeneration, IOLs with a high negative diopter power in the center can be implanted as part of a Galilei telescope. By using high-plus power spectacles, a 2.5x to 4x magnification and a wide field of view can be achieved. Clinical investigation has started recently. Intraocular lenses for the correction of high-grade myopia are being tested by some surgeons. These lenses are made to be implanted in phakic eyes with a clear crystalline lens. Angle-supported and iris-fixated types are under investigation. Longterm results will show the clinical efficacy and safety. Other special intraocular lenses are iris-color lenses and a polymethymethacrylate (PMMA) iris diaphragm. PMID:2083909

  19. 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.

  20. Irlen Lenses and Reading Difficulties.

    ERIC Educational Resources Information Center

    Hoyt, Creig S.

    1990-01-01

    The article reviews three studies (EC 600 064-066) evaluating the effectiveness of using Irlen tinted lenses with reading-disabled persons. The studies are individually critiqued, and recommendations are offered concerning the methodology of further research. Stressed is the need to determine whether a specific syndrome of scotopic sensitivity…

  1. Astrophysical uses of CMB lensing

    NASA Astrophysics Data System (ADS)

    Das, Sudeep

    The future of Cosmic Microwave Background (CMB) research lies in exploiting the arcminute scale secondary anisotropies which encode information about the late time interaction of the CMB photons with the structure in the Universe. A specific form of such interaction is the gravitational lensing of the CMB photons by intervening matter--the main topic of this thesis. Upcoming experiments like the Atacama Cosmology Telescope (ACT) and PLANCK will measure these anisotropies with unprecedented resolution and sensitivity. In four separate papers, laid out as four chapters in this thesis, we present new techniques to model and analyze such high resolution data and explore the implications of such measurements on Cosmology, mainly in the context of CMB lensing. The first chapter describes a novel and accurate method for simulating high resolution lensed CMB maps by ray-tracing through a large scale structure simulation. This method does not adopt the flat sky approximation and retains information from large angular scales in the dark matter distribution. Maps simulated through this method will be instrumental in developing the detection and analysis techniques for CMB lensing in high resolution CMB experiments like ACT. In the second chapter, we describe a new and efficient method for measuring the power spectrum of arcminute resolution CMB maps. At these resolutions, the CMB power spectrum is extremely red and is prone to aliasing of power due to hard edges and point source masks. By combining two new techniques, namely, prewhitening and the adaptive multitaper method, we show that these problems can be efficiently remedied and the uncertainties in the final power spectrum estimate can be reduced by several factors over those obtainable by the now standard methods. These techniques will be also useful for estimating higher order statistics from the maps, like the ones related to the detection of CMB lensing and its cross-correlation with large scale structure tracers. In

  2. 3D printed diffractive terahertz lenses.

    PubMed

    Furlan, Walter D; Ferrando, Vicente; Monsoriu, Juan A; Zagrajek, Przemysław; Czerwińska, Elżbieta; Szustakowski, Mieczysław

    2016-04-15

    A 3D printer was used to realize custom-made diffractive THz lenses. After testing several materials, phase binary lenses with periodic and aperiodic radial profiles were designed and constructed in polyamide material to work at 0.625 THz. The nonconventional focusing properties of such lenses were assessed by computing and measuring their axial point spread function (PSF). Our results demonstrate that inexpensive 3D printed THz diffractive lenses can be reliably used in focusing and imaging THz systems. Diffractive THz lenses with unprecedented features, such as extended depth of focus or bifocalization, have been demonstrated. PMID:27082335

  3. 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.

  4. 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.

  5. Experimental characterization of Fresnel-Köhler concentrators

    NASA Astrophysics Data System (ADS)

    Zamora, Pablo; Benítez, Pablo; Mohedano, Rubén; Cvetković, Aleksandra; Vilaplana, Juan; Li, Yang; Hernández, Maikel; Chaves, Julio; Miñano, Juan C.

    2012-01-01

    Most cost-effective concentrated photovoltaics (CPV) systems are based on an optical train comprising two stages, the first being a Fresnel lens. Among them, the Fresnel-Köhler (FK) concentrator stands out owing to both performance and practical reasons. We describe the experimental measurements procedure for FK concentrator modules. This procedure includes three main types of measurements: electrical efficiency, acceptance angle, and irradiance uniformity at the solar cell plane. We have collected here the performance features of two different FK prototypes (ranging different f-numbers, concentration ratios, and cell sizes). The electrical efficiencies measured in both prototypes are high and fit well with the models, achieving values up to 32.7% (temperature corrected, and with no antireflective coating on SOE or POE surfaces) in the best case. The measured angular transmission curves show large acceptance angles, again perfectly matching the expected values [measured concentration acceptance product (CAP) values over 0.56]. The irradiance pattern on the cell (obtained with a digital camera) shows an almost perfectly uniform distribution, as predicted by raytrace simulations. All these excellent on-sun results confirm the FK concentrator as a potentially cost-effective solution for the CPV market.

  6. 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. PMID:21042389

  7. Performance in test beam of a large-area and light-weight GEM detector with 2D stereo-angle (U-V) strip readout

    NASA Astrophysics Data System (ADS)

    Gnanvo, Kondo; Bai, Xinzhan; Gu, Chao; Liyanage, Nilanga; Nelyubin, Vladimir; Zhao, Yuxiang

    2016-02-01

    A large-area and light-weight gas electron multiplier (GEM) detector was built at the University of Virginia as a prototype for the detector R&D program of the future Electron Ion Collider. The prototype has a trapezoidal geometry designed as a generic sector module in a disk layer configuration of a forward tracker in collider detectors. It is based on light-weight material and narrow support frames in order to minimize multiple scattering and dead-to-sensitive area ratio. The chamber has a novel type of two dimensional (2D) stereo-angle readout board with U-V strips that provides (r,φ) position information in the cylindrical coordinate system of a collider environment. The prototype was tested at the Fermilab Test Beam Facility in October 2013 and the analysis of the test beam data demonstrates an excellent response uniformity of the large area chamber with an efficiency higher than 95%. An angular resolution of 60 μrad in the azimuthal direction and a position resolution better than 550 μm in the radial direction were achieved with the U-V strip readout board. The results are discussed in this paper.

  8. 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.

  9. 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.

  10. Extinction Curves of Lensing Galaxies

    NASA Astrophysics Data System (ADS)

    Elíasdóttir, Árdís

    2006-09-01

    Dust extinction causes light from distant sources to be dimmed on itsway to the observer. In cosmological studies, such as SN Ia studies,it is of great importance that the effects of dust extinction becorrectly accounted for. However, although dust properties, andhence extinction, are expected to vary with redshift, not very muchis known about the extinction properties of high redshift galaxies.This is because the methods traditionally used to study extinctioncurves are only applicable for the most nearby galaxies. Studyinggravitationally lensed quasars is an emerging method of studying thedust extinction of high redshift galaxies. I will present an ESO VLTstudy of 10 such lensing galaxies, with redshifts up to 1. The 10systems display varying amount and type of extinction, with thedoubly imaged quasar B1152+199 showing the greatest extinction with A(V)=2.4 and R_V=2.1 for a Galactic type extinction law.

  11. Optimizing SNAP for Weak Lensing

    NASA Astrophysics Data System (ADS)

    High, F. W.; Ellis, R. S.; Massey, R. J.; Rhodes, J. D.; Lamoureux, J. I.; SNAP Collaboration

    2004-12-01

    The Supernova/Acceleration Probe (SNAP) satellite proposes to measure weak gravitational lensing in addition to type Ia supernovae. Its pixel scale has been set to 0.10 arcsec per pixel as established by the needs of supernova observations. To find the optimal pixel scale for accurate weak lensing measurements we conduct a tradeoff study in which, via simulations, we fix the suvey size in total pixels and vary the pixel scale. Our preliminary results show that with a smaller scale of about 0.08 arcsec per pixel we can minimize the contribution of intrinsic shear variance to the error on the power spectrum of mass density distortion. Currently we are testing the robustness of this figure as well as determining whether dithering yields analogous results.

  12. Lateral shearing with a pair of double Fresnel rhombs for nulling interferometry.

    PubMed

    Baba, Naoshi; Kobayashi, Keita; Kogoma, Yusuke; Murakami, Naoshi

    2011-09-15

    A lateral-shearing interferometer with a pair of double Fresnel rhombs is proposed. Use of Fresnel rhombs enables us to accomplish simultaneously lateral shearing and achromatic nulling. Nulling interferometry with lateral shearing is one of the basic methods for searching directly for extrasolar planets with a segmented-mirror telescope. Here the Thirty-Meter Telescope is considered as a model of a segmented-mirror telescope. Our computer simulations show high extinction for the K-band (2.0-2.4 μm). Optical experiments are conducted to verify the lateral shearing and nulling with a pair of double Fresnel rhombs. PMID:21931407

  13. Fresnel transform as a projection onto a Nijboer-Zernike basis set.

    PubMed

    Wu, Yang; Hillenbrand, Matthias; Zhao, Liang; Sinzinger, Stefan; Kelly, Damien P

    2015-08-01

    The Fresnel transform is widely used in optics to calculate the free-space propagation of paraxial fields. Generally, there is no analytical solution for the Fresnel transform; therefore, the numerical methods are used often. In this Letter, we propose a new semi-analytical method to calculate the Fresnel transform, which is based on an extended Nijboer-Zernike theory. We calculate two examples to investigate how the sampling rate and maximal number of Zernike polynomials affect the accuracy of our results, and then use this method to calculate the reconstruction of two different kinds of holograms. At the end, we discuss the advantages and disadvantages of our method. PMID:26258335

  14. 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.

  15. 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.}

  16. 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

  17. Multimodal characterization of contact lenses

    NASA Astrophysics Data System (ADS)

    Marcus, Michael A.; Compertore, David; Gibson, Donald S.; Herbrand, Matthew E.; Ignatovich, Filipp V.

    2015-10-01

    A table top instrument has been designed, constructed and tested to characterize all of the primary optical and physical properties of contact lenses. Measured optical properties include base power, cylinder power, cylindrical axis, prism, refractive index and wavefront aberrations. Measured physical properties include center thickness, lens diameter and lens sagittal depth. The instrument combines a Shack-Hartmann wavefront sensor (SHWS), a machine vision sensor, and a low coherence light interferometer (LCI) all coaxially aligned into a single tabletop unit. The unit includes a cuvette, mounted in a translatable sample chamber for holding the contact lens under test, and it can be configured to measure wet or dry contact lenses. During operation, the vision sensor measures the diameter of the lens, and locates the center of the lens. The lens is then aligned for other measurements. The vision sensor can also measure various alignment marks on the lens, as well as identify any alpha numerical features, which can be used to associate the lens orientation with the measured aberrations. The LCI measures the center thickness, sagittal depth and index of refraction of the contact lens. The base radius of curvature is then calculated using these measured parameters. The SHWS measures the lenses prescription power, including spherical, cylinder, prism, and higher order wavefront aberrations. NIST traceable calibration artifacts are used to calibrate the SHWS, machine vision and LCI modalities. Repeatability measurements on a contact lens in a saline solution are presented.

  18. 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.

  19. 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.

  20. Gravitational Lensing: Einstein's unfinished symphony

    NASA Astrophysics Data System (ADS)

    Treu, Tommaso; Ellis, Richard S.

    2015-01-01

    Gravitational lensing - the deflection of light rays by gravitating matter - has become a major tool in the armoury of the modern cosmologist. Proposed nearly a hundred years ago as a key feature of Einstein's theory of general relativity, we trace the historical development since its verification at a solar eclipse in 1919. Einstein was apparently cautious about its practical utility and the subject lay dormant observationally for nearly 60 years. Nonetheless there has been rapid progress over the past twenty years. The technique allows astronomers to chart the distribution of dark matter on large and small scales thereby testing predictions of the standard cosmological model which assumes dark matter comprises a massive weakly-interacting particle. By measuring the distances and tracing the growth of dark matter structure over cosmic time, gravitational lensing also holds great promise in determining whether the dark energy, postulated to explain the accelerated cosmic expansion, is a vacuum energy density or a failure of general relativity on large scales. We illustrate the wide range of applications which harness the power of gravitational lensing, from searches for the earliest galaxies magnified by massive clusters to those for extrasolar planets which temporarily brighten a background star. We summarise the future prospects with dedicated ground and space-based facilities designed to exploit this remarkable physical phenomenon.

  1. Fresnel field interaction applied to scattering from a vegetation layer

    NASA Technical Reports Server (NTRS)

    Fung, A. K.; Chen, M. F.; Lee, K. K.

    1987-01-01

    Models for scattering from a vegetation layer treated as a collection of discrete scatterers usually assume far field interaction among scatterers. In a real vegetation medium such as a deciduous forest or a soybean field it is not always true that each leaf is in the far field of other leaves. This paper examines the additional effect when scatterers are permitted to be in the Fresnel zone of one another. Both disc-shaped and needle-shaped leaves are considered. It is found that in general this causes the backscattering coefficient to be lower for the disk-shaped leaves and may be higher or lower for the needle-shaped leaves depending upon polarization, incidence angle, and frequency than those computed under the assumption of conventional far field interaction.

  2. 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.

  3. 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. PMID:26835948

  4. Slope-deviation measurement of Fresnel-shaped mold surfaces.

    PubMed

    Kiefel, Peter; Hornung, Thorsten; Nitz, Peter; Reinecke, Holger

    2016-03-10

    Molds are used to dictate their shape to other materials in embossing or filling processes. In optics fabrication especially, the exact surface slope of the polymer replica is of high relevance. The quality control of molds is challenging: non-invasive, optical metrologies struggle with shiny surfaces that minimize the scattering of light. In addition, the inspection of complex shaped molds with a stepped optical surface can be difficult. In response, the authors show a backward ray-tracing approach combined with fringe-reflection technique to determine the slopes of a Fresnel-shaped mold surface with topography features in the magnitude order of a quarter millimeter. The error is kept small by stitching together several measurements with different sample rotations. PMID:26974807

  5. 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.

  6. 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.

  7. 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...

  8. 30 CFR 18.30 - Windows and lenses.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 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. 30 CFR 18.30 - Windows and lenses.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 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...

  10. 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...

  11. 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...

  12. 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.

  13. 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.

  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. CMB lensing and primordial non-Gaussianity

    SciTech Connect

    Hanson, Duncan; Smith, Kendrick M.; Challinor, Anthony; Liguori, Michele

    2009-10-15

    We study the effects of gravitational lensing on the estimation of non-Gaussianity from the bispectrum of the CMB temperature anisotropies. We find that the effect of lensing on the bispectrum may qualitatively be described as a smoothing of the acoustic features analogous to the temperature power spectrum. In contrast to previous results, for a Planck-like experiment which is cosmic-variance limited to l{sub max}=2000, we find that lensing causes no significant degradation of our ability to constrain the non-Gaussianity amplitude f{sub NL} for both local and equilateral configurations, provided that the biases due to the cross correlation between the lensing potential and the integrated-Sachs-Wolfe contribution to the CMB temperature are adequately understood. With numerical simulations, we also verify that low-order Taylor approximations to the lensed bispectrum and integrated-Sachs-Wolfe-lensing biases are accurate.

  16. Prediction of Impact Shock Vibrations at Tennis Player's Wrist Joint: Comparison between Conventional Weight Racket and Light Weight Racket with Super Large Head Size

    NASA Astrophysics Data System (ADS)

    Kawazoe, Yoshihiko; Takeda, Yukihiro; Nakagawa, Masamichi; Casolo, Federico; Tomosue, Ryoso; Yoshinari, Keiko

    The lightweight racket with handle-light configuration and large head size is recent tendency of high-tech tennis rackets, increasing power or post-impact ball velocity with an increasing racket swing speed. This paper investigated the performance of lightweight tennis racket with super-large head size in terms of feel or comfort. It predicted the effect of the mass and mass distribution of super-large sized rackets on the impact shock vibrations of the racket handle and the player's wrist joint when a player hits a flat forehand drive. The prediction is based on the identification of the racket characteristics, the damping of the racket-arm system, equivalent mass of the player's arm system and the approximate nonlinear impact analysis in tennis. A super-light weight balanced racket (mass: 292 g, the center of gravity LG: 363 mm from the butt end) and a conventional weight and weight balanced racket (349 g, LG: 323 mm) are selected as representatives. They are the super-large sized rackets made of carbon graphite with a head size of 120 square inches and the same geometry. The result showed that the shock vibration of the super-light weight balanced racket with super-large sized head is much larger than that of the conventional weight balanced type racket. It also showed that the sweet area of the former in terms of the shock vibration shifts from the center to the topside on the racket face compared to the latter. This is because the location of the grip on the racket handle is further from the location of the node on the handle of the first mode of super-light racket than that of the conventional weight racket.

  17. Design, fabrication, and characterization of Fresnel lens array with spatial filtering for passive infrared motion sensors

    NASA Astrophysics Data System (ADS)

    Cirino, Giuseppe A.; Barcellos, Robson; Morato, Spero P.; Bereczki, Allan; Neto, Luiz G.

    2006-09-01

    A cubic-phase distribution is applied in the design, fabrication and characterization of inexpensive Fresnel lens arrays for passive infrared motion sensors. The resulting lens array produces a point spread function (PSF) capable of distinguish the presence of humans from pets by the employment of the so-called wavefront coding method. The cubic phase distribution used in the design can also reduce the optical aberrations present in the system. This aberration control allows a high tolerance in the fabrication of the lenses and in the alignment errors of the sensor. In order to proof the principle, a lens was manufactured on amorphous hydrogenated carbon thin film, by well-known micro fabrication process steps. The optical results demonstrates that the optical power falling onto the detector surface is attenuated for targets that present a mass that is horizontally distributed in space (e.g. pets) while the optical power is enhanced for targets that present a mass vertically distributed in space (e.g. humans). Then a mould on steel was fabricated by laser engraving, allowing large-scale production of the lens array in polymeric material. A polymeric lens was injected and its optical transmittance was characterized by Fourier Transform Infrared Spectrometry technique, which has shown an adequate optical transmittance in the 8-14 μm wavelength range. Finally the performance of the sensor was measured in a climate-controlled test laboratory constructed for this purpose. The results show that the sensor operates normally with a human target, with a 12 meter detection zone and within an angle of 100 degrees. On the other hand, when a small pet runs through a total of 22 different trajectories no sensor trips are observed. The novelty of this work is the fact that the so-called pet immunity function was implemented in a purely optical filtering. As a result, this approach allows the reduction of some hardware parts as well as decreasing the software complexity, once the

  18. Weak lensing of the primary CMB bispectrum

    SciTech Connect

    Cooray, Asantha; Sarkar, Devdeep; Serra, Paolo

    2008-06-15

    The bispectrum of cosmic microwave background (CMB) anisotropies is a well-known probe of the non-Gaussianity of primordial perturbations. Just as the intervening large-scale structure modifies the CMB angular power spectrum through weak gravitational lensing, the CMB primary bispectrum generated at the last scattering surface is also modified by lensing. We discuss the lensing modification to the CMB bispectrum and show that lensing leads to an overall decrease in the amplitude of the primary bispectrum at multipoles of interest between 100 and 2000 through additional smoothing introduced by lensing. Since weak lensing is not accounted for in current estimators of the primordial non-Gaussianity parameter, the existing measurements of f{sub NL} of the local model with WMAP out to l{sub max}{approx}750 is biased low by about 6%. For a high resolution experiment such as Planck, the lensing modification to the bispectrum must be properly included when attempting to estimate the primordial non-Gaussianity or the bias will be at the level of 30%. For Planck, weak lensing increases the minimum detectable value for the non-Gaussianity parameter of the local type f{sub NL} to 7 from the previous estimate of about 5 without lensing. The minimum detectable value of f{sub NL} for a cosmic variance limited experiment is also increased from less than 3 to {approx}5.

  19. 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. PMID:19466190

  20. 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)

  1. cluster-lensing: Tools for calculating properties and weak lensing profiles of galaxy clusters

    NASA Astrophysics Data System (ADS)

    Ford, Jes

    2016-05-01

    The cluster-lensing package calculates properties and weak lensing profiles of galaxy clusters. Implemented in Python, it includes cluster mass-richness and mass-concentration scaling relations, and NFW halo profiles for weak lensing shear, the differential surface mass density ΔΣ(r), and for magnification, Σ(r). Optionally the calculation will include the effects of cluster miscentering offsets.

  2. 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. PMID:24663719

  3. Electrically controllable Fresnel lens in 90° twisted nematic liquid crystals.

    PubMed

    Kuo, Chie-Tong; Li, Chien-Yu; Lin, Shih-Hung; Yeh, Hui-Chen

    2015-10-01

    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. PMID:26480119

  4. Rigorous expressions for the Fresnel equations at interfaces between absorbing media.

    PubMed

    Maezawa, Hideki; Miyauchi, Hiroshi

    2009-02-01

    When conventional Fresnel theory is applied to absorbing multilayer systems, a slight discrepancy with respect to the principle of conservation of energy arises. Here we solve this long-perceived problem and present rigorous expressions for the Fresnel equations generally applicable to interfaces between isotropic absorbing media. These equations satisfy the conservation law automatically and coincide naturally with the conventional ones in reflection by simple mirrors placed in a vacuum. PMID:19183685

  5. 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.

  6. Weak lensing by galaxy troughs

    NASA Astrophysics Data System (ADS)

    Gruen, Daniel

    2016-06-01

    Galaxy troughs, i.e. underdensities in the projected galaxy field, are a weak lensing probe of the low density Universe with high signal-to-noise ratio. I present measurements of the radial distortion of background galaxy images and the de-magnification of the CMB by troughs constructed from Dark Energy Survey and Sloan Digital Sky Survey galaxy catalogs. With high statistical significance and a relatively robust modeling, these probe gravity in regimes of density and scale difficult to access for conventional statistics.

  7. 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.

  8. Gravitational Lensing in TeVe S

    NASA Astrophysics Data System (ADS)

    Chiu, Mu-Chen; Ko, Chung-Ming; Tian, Yong

    Gravitational Lensing is an important tool to understand the "missing mass" problem, especially for Modified Gravity. Recently, Bekenstein proposed a relativistic gravitation theory for Modified Newtonian Dynamics (MOND) paradigm which resolves the "missing mass" problem well on abnormal dynamical behaviors in extragalactic region. Our work follow Bekenstein's approach to investigating gravitational lensing to get theoretical prediction.

  9. Bayesian Inference of CMB Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    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.

  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. Aberrations in asymmetrical electron lenses.

    PubMed

    Fitzgerald, J P S; Word, R C; Könenkamp, R

    2012-08-01

    Starting from well established knowledge in light-optics we explore the question if electron-optical aberration can be improved in asymmetrical electron lenses. We show that spherical as well as chromatic aberration coefficients are reduced in asymmetric electrostatic einzel lenses when the center electrode is moved away from the center position towards the entrance electrode. Relative improvements up to 40% for both the chromatic and the spherical aberration coefficients can be obtained. We use analytical and numerical calculations to confirm this result for exemplary cases of a lens with fixed length and working distance. The agreement of the two calculation methods is very good. We then derive an estimate for the electron-optical aberration coefficients from light-optics. The derived expressions for chromatic and spherical aberrations are somewhat simpler than the ones derived from electron-optics as they involve integrals only over the electrostatic potential, not over the electron paths. The estimated formulas still agree well with the electron optical calculations. Overall, we are tempted to suggest that the enormous knowledge base of light optics can provide considerable guidance for electron-optical applications. PMID:22206603

  12. Time delay in Swiss cheese gravitational lensing

    SciTech Connect

    Chen, B.; Kantowski, R.; Dai, X.

    2010-08-15

    We compute time delays for gravitational lensing in a flat {Lambda} dominated cold dark matter Swiss cheese universe. We assume a primary and secondary pair of light rays are deflected by a single point mass condensation described by a Kottler metric (Schwarzschild with {Lambda}) embedded in an otherwise homogeneous cosmology. We find that the cosmological constant's effect on the difference in arrival times is nonlinear and at most around 0.002% for a large cluster lens; however, we find differences from time delays predicted by conventional linear lensing theory that can reach {approx}4% for these large lenses. The differences in predicted delay times are due to the failure of conventional lensing to incorporate the lensing mass into the mean mass density of the universe.

  13. Spherical aberration in electrically thin flat lenses.

    PubMed

    Ruphuy, Miguel; Ramahi, Omar M

    2016-08-01

    We analyze the spherical aberration of a new generation of lenses made of flat electrically thin inhomogeneous media. For such lenses, spherical aberration is analyzed quantitatively and qualitatively, and comparison is made to the classical gradient index rod. Both flat thin and thick lenses are made of gradient index materials, but the physical mechanisms and design equations are different. Using full-wave three-dimensional numerical simulation, we evaluate the spherical aberrations using the Maréchal criterion and show that the thin lens gives significantly better performance than the thick lens (rod). Additionally, based on ray tracing formulation, third-order analysis for longitudinal aberration and optical path difference are presented, showing strong overall performance of thin lenses in comparison to classical rod lenses. PMID:27505651

  14. Fresnel-Kirchhoff theory applied to terrain diffraction problems

    NASA Astrophysics Data System (ADS)

    Whitteker, J. H.

    1990-09-01

    Fresnel-Kirchhoff theory is adapted to the problem of finding the diffraction attenuation at VHF and UHF over terrain profiles of arbitrary shape. Approximations are based on the assumptions of small wavelength and small diffraction angles. As a preliminary step, the theory is applied to the multiple-knife-edge problem. The field is found as a function of height above each knife edge in turn. In an application of Huygens' principle, an integration over the field above one knife edge provides the field at any point above the next. This formulation is equivalent to knife-edge formulations used in the past. Then each pair of neighboring knife edges is bridged with an imperfectly reflecting plane surface, representing the terrain. Huygens' principle is used again for the reflected wave, neglecting backscatter. The field found in this way is accurate for a good reflector but not a poor one. An analytical comparison shows agreement with rigorous diffraction theory for the problem of a plane wave incident on a perfectly reflecting wedge. Numerical comparisons with rigorous diffraction theory for a spherical Earth and for a small-radius hill (approximated with linear segments) show agreement to within 1.5 dB for the parameters chosen.

  15. Fabrication of Fresnel microlens with excimer laser contour ablation

    NASA Astrophysics Data System (ADS)

    Wójcik, Michał R.; Antończak, Arkadiusz J.; Kozioł, Paweł E.; Łazarek, Łukasz K.; Stepak, Bogusz D.; Abramski, Krzysztof M.

    2014-08-01

    Laser micromachining systems based on excimer lasers are usually oriented to work with mask projection regime because of the low pulse repetition rate as well as large beam aperture of the laser source. In case of fabricating of the complex 3D structures, this approach introduces a number of limitations. Alternative solution might be usage of direct writing laser mode. Some examples of the so called contour ablation approach for fabricating microlenses with an absolutely monotonically changing cross-sectional profile are presented in the literature. Based on this idea and introducing new variables like automatic mask selection as well as optimizing process algorithms led us to obtain more versatile method for shape approximation. Hence, there were fabricated structures with cross-sectional profiles described as functions that are monotonic on specified intervals such as Fresnel microlenses. In this paper we describe approximation of process parameters for obtaining desired cross-sectional profiles and finally fabrication of few exemplary microlenses. All structures were characterized by a digital optical microscopy and compared to the given profiles. The accuracy of reproduction of the desired structures at the level of single microns was achieved.

  16. Moessbauer-Fresnel zone plate as nuclear monochromator

    SciTech Connect

    Mooney, T.M.; Alp, E.E.; Yun, W.B.

    1992-06-01

    Zone plates currently used in x-ray optics derive their focusing power from (a spatial variation of) the electronic refractive index -- that is, from the collective effect of electronic x-ray-scattering amplitudes. Nuclei also scatter x rays, and resonant nuclear-scattering amplitudes, particularly those associated with Moessbauer fluorescence, can dominate the refractive index for x-rays whose energies are very near the nuclear-resonance energy. A zone plate whose Fresnel zones are filled alternately with {sup 57}Fe and {sup 56}Fe ({sup 57}Fe has a nuclear resonance of natural width {Gamma} = 4.8 nano-eV at 14.413 keV; {sup 56}Fe has no such resonance) has a resonant focusing efficiency; it focuses only those x-rays whose energies are within several {Gamma} of resonance. When followed by an absorbing screen with a small pinhole, such a zone plate can function as a synchrotron-radiation monochromator with an energy resolution of a few parts in 10{sup 12}. The energy-dependent focusing efficiency and the resulting time-dependent response of a resonant zone plate are discussed.

  17. Fresnel-Fizeau drag: Invisibility conditions for all inertial observers

    NASA Astrophysics Data System (ADS)

    Halimeh, Jad C.; Thompson, Robert T.

    2016-03-01

    It was recently shown [J. C. Halimeh et al., Phys. Rev. A 93, 013850 (2016), 10.1103/PhysRevA.93.013850] that as a result of the Doppler effect, inherently dispersive single-frequency ideal free-space invisibility cloaks in relative motion to an observer can only cloak light whose frequency in the cloak frame coincides with the operational frequency of the cloak, although an infinite number of such rays exist for any cloak motion. In this article, we show analytically and through ray-tracing simulations that even though this relationship can be relaxed by simplifying the ideal invisibility cloak into a broadband amplitude cloak, Fresnel-Fizeau drag uncloaks the phase of light in the inertial frame of the cloak thereby compromising its amplitude cloaking in all other inertial frames. In other words, only an invisibility device that perfectly cloaks both the amplitude and the phase of light in its own inertial frame will also (perfectly) cloak this light in any other inertial frame. The same conclusion lends itself to invisible objects that are not cloaks, such as the invisible sphere.

  18. Light weight, high-speed, and self-powered wireless fiber optic sensor (WiFOS) structural health monitor system for avionics and aerospace environments

    NASA Astrophysics Data System (ADS)

    Mendoza, Edgar A.; Kempen, Cornelia; Sun, Sunjian; Esterkin, Yan

    2014-09-01

    This paper describes recent progress towards the development of an innovative light weight, high-speed, and selfpowered wireless fiber optic sensor (WiFOS™) structural health monitor system suitable for the onboard and in-flight unattended detection, localization, and classification of load, fatigue, and structural damage in advanced composite materials commonly used in avionics and aerospace systems. The WiFOS™ system is based on ROI's advancements on monolithic photonic integrated circuit microchip technology, integrated with smart power management, on-board data processing, wireless data transmission optoelectronics, and self-power using energy harvesting tools such as solar, vibration, thermoelectric, and magneto-electric. The self-powered, wireless WiFOS™ system offers a versatile and powerful SHM tool to enhance the reliability and safety of avionics platforms, jet fighters, helicopters, commercial aircraft that use lightweight composite material structures, by providing comprehensive information about the structural integrity of the structure from a large number of locations. Immediate SHM applications are found in rotorcraft and aircraft, ships, submarines, and in next generation weapon systems, and in commercial oil and petrochemical, aerospace industries, civil structures, power utilities, portable medical devices, and biotechnology, homeland security and a wide spectrum of other applications.

  19. A coatable, light-weight, fast-response nanocomposite sensor for the in situ acquisition of dynamic elastic disturbance: from structural vibration to ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Zeng, Zhihui; Liu, Menglong; Xu, Hao; Liu, Weijian; Liao, Yaozhong; Jin, Hao; Zhou, Limin; Zhang, Zhong; Su, Zhongqing

    2016-06-01

    Inspired by an innovative sensing philosophy, a light-weight nanocomposite sensor made of a hybrid of carbon black (CB)/polyvinylidene fluoride (PVDF) has been developed. The nanoscalar architecture and percolation characteristics of the hybrid were optimized in order to fulfil the in situ acquisition of dynamic elastic disturbance from low-frequency vibration to high-frequency ultrasonic waves. Dynamic particulate motion induced by elastic disturbance modulates the infrastructure of the CB conductive network in the sensor, with the introduction of the tunneling effect, leading to dynamic alteration in the piezoresistivity measured by the sensor. Electrical analysis, morphological characterization, and static/dynamic electromechanical response interrogation were implemented to advance our insight into the sensing mechanism of the sensor, and meanwhile facilitate understanding of the optimal percolation threshold. At the optimal threshold (∼6.5 wt%), the sensor exhibits high fidelity, a fast response, and high sensitivity to ultrafast elastic disturbance (in an ultrasonic regime up to 400 kHz), yet with an ultralow magnitude (on the order of micrometers). The performance of the sensor was evaluated against a conventional strain gauge and piezoelectric transducer, showing excellent coincidence, yet a much greater gauge factor and frequency-independent piezoresistive behavior. Coatable on a structure and deployable in a large quantity to form a dense sensor network, this nanocomposite sensor has blazed a trail for implementing in situ sensing for vibration- or ultrasonic-wave-based structural health monitoring, by striking a compromise between ‘sensing cost’ and ‘sensing effectiveness’.

  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. PMID:26841116

  1. Compact and Light-Weight Solar Spaceflight Instrument Designs Utilizing Newly Developed Miniature Free-Standing Zone Plates: EUV Radiometer and Limb-Scanning Monochromator

    NASA Astrophysics Data System (ADS)

    Seely, J. F.; McMullin, D. R.; Bremer, J.; Chang, C.; Sakdinawat, A.; Jones, A. R.; Vest, R.

    2014-12-01

    Two solar instrument designs are presented that utilize newly developed miniature free-standing zone plates having interconnected Au opaque bars and no support membrane resulting in excellent long-term stability in space. Both instruments are based on a zone plate having 4 mm outer diameter and 1 to 2 degree field of view. The zone plate collects EUV radiation and focuses a narrow bandpass through a pinhole aperture and onto a silicon photodiode detector. As a miniature radiometer, EUV irradiance is accurately determined from the zone plate efficiency and the photodiode responsivity that are calibrated at the NIST SURF synchrotron facility. The EUV radiometer is pointed to the Sun and measures the absolute solar EUV irradiance in high time cadence suitable for solar physics and space weather applications. As a limb-scanning instrument in low earth orbit, a miniature zone-plate monochromator measures the extinction of solar EUV radiation by scattering through the upper atmosphere which is a measure of the variability of the ionosphere. Both instruments are compact and light-weight and are attractive for CubeSats and other missions where resources are extremely limited.

  2. Fixation of Light Weight Polypropylene Mesh with n-Butyl-2-cyanocrylate in Pelvic Floor Surgery: Experimental Design Approach in Sheep for Effectiveness Evaluation

    PubMed Central

    Barbosa, Sandra; Nieves, Tania; García, Félix; Cepeda, Eva; Moll, Xavier; Marco, Alberto; Weis, Christine; Turon, Pau; Vergara, Patri

    2015-01-01

    Objective. The aim of this study was to find a proper experimental design and to evaluate n-butyl-2-cyanoacrylate (Histoacryl) as a fixation method for a light-weight and large pore PP mesh (Synthetic PP Mesh-1) using the sheep as an animal model. Methods. Posterior vaginal implantation by means of episiotomy was used to implant 8 ewes which were evaluated macroscopically and histologically at 3 months (n = 4) and 6 months (n = 4) post-surgery. In previous pilot studies anterior vaginal implantation was evaluated, as well as different synthetic mesh materials, sizes and fixation methods (n = 1 to 3) during three weeks. In all cases a clinical evaluation of the animal was performed. Results. A reduction in the mesh size (Synthetic PP Mesh-1) together with precise application of the surgical glue Histoacryl to fix the mesh yielded significantly better histocompatibility results (P < 0.01) compared to larger size or other fixation methods. Conclusion. The combination of Synthetic PP Mesh-1 with Histoacryl offered a high degree of graft integration without vaginal ulceration and a minimal foreign body reaction, being the sheep a proper animal model to test these types of medical devices. PMID:26221605

  3. 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

  4. 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.

  5. 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.

  6. HST Observations of New Class Gravitational Lenses

    NASA Astrophysics Data System (ADS)

    Jackson, Neal

    1995-07-01

    We propose to examine a few of the very best lens candidates from a new gravitational lens survey, the Cosmic Lens All-Sky Survey (CLASS) made with the VLA. We are virtually certain that we have one new lens system (1600+434) and another (1609+655) has a radio configuration which almost invariably indicates gravitational lensing. The other cases are systems which have a high probability of being lenses (statistically we would expect at least 5 of the 10 objects should be lensed, since we have imaged >3000 radio sources and experience shows that 1 in 500 are lensed). All have separations which make them difficult to study from the ground and therefore uniquely suited to the capabilities of the HST. In this investigation we will study 1600+434 and 1609+655 and attempt to image the lensing galaxy. We will image the remainder in an attempt to confirm their lens status (which requires 0.1" resolution imaging typically) and search for lensing galaxies and/or clusters in those found to be lensed systems.

  7. Gravitational lensing in observational cosmology

    NASA Astrophysics Data System (ADS)

    Nottale, L.

    This paper reviews some previous theoretical and observational results concerning the various effects of gravitational lensing, and also presents still unpublished results in this field. The theoretical section deals with the Optical Scalar Equation (OSE) approach. We recall the form of these equations, which relate the deformations of the cross sectional area of a light beam to the material and energetic distribution it encounters, via the two basic contributions to lensing, the matter or Ricci term and the shear term. The introduction of a new distance, the optical distance, allows to write the OSE in a simplified way from which new solutions are easily derived. We demonstrate here that a general form may be obtained for the amplification formula in the exact relativistic treatment, provided the Universe is assumed to be Friedmannian in the mean. New results are also presented concerning the probability distribution of amplifications, the relation from matter term to shear terms (the first ones give the mean of the second ones) and the problem of energy conservation. We recall how our method let to an analytical formula yielding the amplification by any number of lenses placed anywhere along the line of sight and present new general solutions for lensing by large scale density inhomogeneities. The gravitational redshift effects are also considered, either due to the crossing by photons of inhomogeneities, or intrinsic to them ; generalized solutions to the last problem are given. Some observational evidence concerning various lensing effects, either statistical or applying to individual sources, are considered. We first recall how the dependence of the amplification formula on the various physical parameters points towards the optimisation of lensing by very rich clusters of galaxies lying at redshifts around 0.7, which may give rise to very large amplifications for reasonable values of the density parameter. Recent results concerning a statistical effect of

  8. Cosmological Applications of Strong Gravitational Lensing

    NASA Astrophysics Data System (ADS)

    Paraficz, Danuta

    2009-11-01

    One of the most intriguing recent results in physics is the growing evidence that an unknown energy field and an unknown kind of matter are the major components of the Universe (70% and 30%, respectively; see e.g. Riess et al. 1998, Spergel et al. 2007). Understanding and estimating the precise value of the energy density of the two above components, together with measuring the Hubble constant that determines the age of the Universe, is a major goal of modern astrophysics. An interesting method for estimating these parameters is strong gravitational lensing of quasars (QSOs). As shown by Refsdal (1964), H0, !m and !! can be measured based on the time delay ("t) between multiply lensed images of QSOs, because "t depends on H0 and on the distances to lens and source, hence!m and !!. Determination of cosmological parameters using gravitational lensing suffers from some degeneracies, but it is based on well understood physics and unlike distance ladder methods there are no calibration issues. Moreover, it has an advantage over some of the leading methods (such as Type Ia SNe) in that it is a purely cosmological approach. In this thesis, the property of strong gravitational lensing - time delay - is extensively explored. Strong gravitational lensing, and in particular time delays, are investigated here both theoretically and observationally. The focus is on the time delay as a cosmological and astrophysical tool to constrain H0, !m, !!, and to measure the masses of lensing galaxies. The first Chapter presents a historical background of gravitational lensing. It explains the process involved in creating the theory of gravitational lenses. It shows how Newton and then Einstein developed the concept and how Refsdal and others made it a cosmological tool. We present in more detail how gravitational lensing influenced the history of physics by being the first proof of Einstein's theory of gravity. The Chapter ends by discussing the first observational discovery of a strong

  9. Simultaneous Inversion for Velocity and Reflector Geometry Using Multi-phase Fresnel Volume Rays

    NASA Astrophysics Data System (ADS)

    Bai, Chao-ying; Li, Xing-wang; Huang, Guo-jiao; Greenhalgh, Stewart

    2014-07-01

    Traditional ray tomography methods based on the high frequency assumption are sometimes unable to obtain a high resolution tomographic picture due to a deficient coverage of ray paths in real applications, especially for low velocity anomalous regions. In contrast, finite-frequency ray theory is more suitable for handling real seismic propagation problems because the travel time depends not only on the velocity distribution along a central ray (or traditional geometric ray), but also on the velocity values within a region (referred to as the first Fresnel Volume) which incorporates the central ray. In this study, we develop an algorithm to calculate multi-phase Fresnel Volume finite-frequency rays, and then present an inversion method to simultaneous invert for both velocity and reflector geometry by using these multi-phase Fresnel Volume finite-frequency rays. Using synthetic data examples, we compare the reconstructions of the velocity field and the reflector orientation using the Fresnel Volume ray tomographic methods and the traditional ray tomography approach. Results show that the former is advantageous over the latter, especially when the ray density is relatively low. An additional benefit of the Fresnel Volume finite-frequency ray tomographic method is that it can start with a low frequency to capture the coarse velocity structure, thereby mitigating the local minimum trapping problem, and then be tuned to a high frequency for delineating the fine velocity structure.

  10. 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.

  11. CCTV lenses for video meteor astronomy

    NASA Astrophysics Data System (ADS)

    Wiśniewski, M.; Olech, A.; Krasnowski, M.; Zloczewski, K.; Mularczyk, K.; Kedzierski, P.; Jonderko, W.

    2005-02-01

    We present the results of CCTV lens tests made last year at the Ostrowik Observatory by observers of the Comets and Meteors Workshop. A total of 13 lenses with different parameters were tested. The limiting magnitudes, size of field of view, distortion and off-axis aberrations were measured. The Computar f/1.2, f=4 mm appeared to be the best lens tested. We also note the good marks of both Ernitecs which were finally chosen as the lenses which will be used in our projects. Surprisingly, the very fast lenses which are popular in video meteor astronomy seem to be much worse that their f/1.2 rivals.

  12. Edge shape and comfort of rigid lenses.

    PubMed

    La Hood, D

    1988-08-01

    One of the main factors determining the comfort of a rigid contact lens is the shape of the edge. The comfort of four different contact lens edge shapes was assessed with four unadapted subjects in a randomized masked trial. Lenses with well rounded anterior edge profiles were found to be significantly more comfortable than lenses with square anterior edges. There was no significant difference in subjective comfort between a rounded and square posterior edge profile. The results suggest that the interaction of the edge with the eyelid is more important in determining comfort than edge effects on the cornea, when lenses are fitted according to a corneal alignment philosophy. PMID:3177585

  13. 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. PMID:23274760

  14. 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. PMID:23609732

  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. Adjustable fluidic lenses for ophthalmic corrections

    PubMed Central

    Marks, Randall; Mathine, David L.; Peyman, Gholam; Schwiegerling, Jim; Peyghambarian, Nasser

    2010-01-01

    We report on two fluidic lenses that have been developed for ophthalmic applications. The lenses use a circular aperture to demonstrate optical powers between −20 and +20 D and a rectangular aperture to demonstrate astigmatism with values ranging from 0 to 8 D. Measurements of image quality were made with the fluidic lens using a model eye. Both lenses were variable and controllable by adjusting the fluid volume of the lens. To the best of our knowledge this is the first demonstration of a continuously variable lens for control of astigmatism. PMID:19373359

  17. Electrically-tunable liquid crystal lenses and applications

    NASA Astrophysics Data System (ADS)

    Lin, Yi-Hsin; Chen, Hung-Shan; Chen, Ming-Syuan

    2013-03-01

    In this paper, the electrically-tunable liquid crystal (LC) lenses and the applications are reviewed. We introduce the basic mechanism of LC phase modulation first. LC lenses are categorized based on different operating principles: 1) Gradient Index (GRIN) LC lenses with a homogeneous cell gap, 2) non-GRIN LC lenses with an inhomogeneous cell gap, 3) diffractive LC lenses, and 4) LC lenses controlled by polarizations. To remove the polarization independency, we also summarize polarization independent LC phase modulations. Many promising applications based on LC lenses are also summarized, such as imaging system, pico projectors, optical zoom systems, ophthalmic applications, and solar systems.

  18. Ultralight stretched Fresnel lens solar concentrator for space power applications

    NASA Astrophysics Data System (ADS)

    O'Neill, Mark J.; Piszczor, Michael F.; Eskenazi, Michael I.; McDanal, A. J.; George, Patrick J.; Botke, Matthew M.; Brandhorst, Henry W.; Edwards, David L.; Hoppe, David T.

    2003-12-01

    A unique ultra-light solar concentrator has recently been developed for space power applications. The concentrator comprises a flexible, 140-micron-thick, line-focus Fresnel lens, made in a continuous process from space-qualified transparent silicone rubber material. For deployment and support in space, end arches are used to tension the lens material in a lengthwise fashion, forming a cylindrical stressed membrane structure. The resultant lens provides high optical efficiency, outstanding tolerance for real-world errors and aberrations, and excellent focusing performance. The stretched lens is used to collect and focus sunlight at 8X concentration onto high-efficiency multi-junction photovoltaic cells, which directly convert the incident solar energy to electricity. The Stretched Lens Array (SLA) has been measured at over 27% net solar-to-electric conversion efficiency for space sunlight, and over 30% net solar-to-electric conversion efficiency for terrestrial sunlight. More importantly, the SLA provides over 180 W/kg specific power at a greatly reduced cost compared to conventional planar photovoltaic arrays in space. The cost savings are due to the use of 85% less of the expensive solar cell material per unit of power produced. SLA is a direct descendent of the award-winning SCARLET array which performed flawlessly on the NASA/JPL Deep Space 1 spacecraft from 1998-2001. The paper describes the new concentrator in more detail, including its materials and configuration, and shows the novel approach to deployment and support, which leads to unprecedented performance metrics for a space power system.

  19. The S-ordered Operator Expansions of One-mode and Two-mode Fresnel Operators and their Applications

    NASA Astrophysics Data System (ADS)

    Du, Jian-ming; Ren, Gang; Yu, Hai-jun; Zhang, Wen-hai

    2016-08-01

    By using the technique of integration within the s-ordered product of operators (IWSOP), we first deduce the s-ordered expansion of the one-mode and two-mode Fresnel operators. Employing the s-ordered operator expansion formula, the matrix elements of one-mode and two-mode Fresnel operator in the number state representation are also obtained, respectively.

  20. 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.

  1. Tear exchange and contact lenses: A review

    PubMed Central

    Muntz, Alex; Subbaraman, Lakshman N.; Sorbara, Luigina; Jones, Lyndon

    2015-01-01

    Tear exchange beneath a contact lens facilitates ongoing fluid replenishment between the ocular surface and the lens. This exchange is considerably lower during the wear of soft lenses compared with rigid lenses. As a result, the accumulation of tear film debris and metabolic by-products between the cornea and a soft contact lens increases, potentially leading to complications. Lens design innovations have been proposed, but no substantial improvement in soft lens tear exchange has been reported. Researchers have determined post-lens tear exchange using several methods, notably fluorophotometry. However, due to technological limitations, little remains known about tear hydrodynamics around the lens and, to-date, true tear exchange with contact lenses has not been shown. Further knowledge regarding tear exchange could be vital in aiding better contact lens design, with the prospect of alleviating certain adverse ocular responses. This article reviews the literature to-date on the significance, implications and measurement of tear exchange with contact lenses. PMID:25575892

  2. Gravitational lensing of active galactic nuclei.

    PubMed Central

    Hewitt, J N

    1995-01-01

    Most of the known cases of strong gravitational lensing involve multiple imaging of an active galactic nucleus. The properties of lensed active galactic nuclei make them promising systems for astrophysical applications of gravitational lensing; in particular, they show structure on scales of milliseconds of arc to tens of seconds of arc, they are variable, and they are polarized. More than 20 cases of strong gravitational lenses are now known, and about half of them are radio sources. High-resolution radio imaging is making possible the development of well-constrained lens models. Variability studies at radio and optical wavelengths are beginning to yield results of astrophysical interest, such as an independent measure of the distance scale and limits on source sizes. PMID:11607613

  3. Contact lenses and the work environment.

    PubMed

    Mäkitie, J

    1984-01-01

    Controversial opinions have been presented about the use of contact lenses in industrial environments. Work environments contain few obstacles to the use of contact lenses, but many occupations are associated with the risk of excessive difficulties, spoilation , irritation, or complications. From the radiant energy the shorter (280 nm) ultraviolet (UV) wavelengths and the longer (1300 nm) infra-red (IR) wavelengths are absorbed by contact lenses, the absorption increases their temperature and may cause corneal complications. Protective glasses, however, absorb more than 99.5% of the UV and IR energy and thus provide sufficient protection for contact lens wearers exposed to UV or IR radiation. The advantages and risks of contact lenses in industrial work are discussed. PMID:6328841

  4. Current indications for scleral contact lenses.

    PubMed

    Foss, A J; Trodd, T C; Dart, J K

    1994-04-01

    Scleral contact lenses have been largely superseded by corneal contact lenses, but they still retain a role as a treatment of choice for a small group of patients who have tried other types of contact lens wear without success and who are not good candidates for surgery. We performed a cross sectional survey of 44 patients attending clinics at Moorfields Eye Hospital who were successful long-term scleral contact lens wearers and reviewed their indications. Twenty-one patients had been fit to improve visual acuity, 20 for therapeutic indications, and three for cosmetic reasons. Scleral lenses were most useful were with patients with ocular surface disorders, such as Stevens-Johnson syndrome, and for visual rehabilitation of patients with grossly irregular corneal topography. All patients were benefiting from scleral contact lens wear, and none had serious complications as a result of the scleral lens wear. We conclude that all ophthalmic departments should have access to these lenses. PMID:8044976

  5. Nanofocusing Parabolic Refractive X-Ray Lenses

    SciTech Connect

    Schroer, C.G.; Kuhlmann, M.; Hunger, U.T.; Guenzler, T.F.; Kurapova, O.; Feste, S.; Lengeler, B.; Drakopoulos, M.; Somogyi, A.; Simionovici, A. S.; Snigirev, A.; Snigireva, I.

    2004-05-12

    Parabolic refractive x-ray lenses with short focal distance can generate intensive hard x-ray microbeams with lateral extensions in the 100nm range even at short distance from a synchrotron radiation source. We have fabricated planar parabolic lenses made of silicon that have a focal distance in the range of a few millimeters at hard x-ray energies. In a crossed geometry, two lenses were used to generate a microbeam with a lateral size of 330nm by 110nm at 25keV in a distance of 41.8m from the synchrotron radiation source. First microdiffraction and fluorescence microtomography experiments were carried out with these lenses. Using diamond as lens material, microbeams with lateral size down to 20nm and below are conceivable in the energy range from 10 to 100keV.

  6. Cooking with Strong Lenses and Other Ingredients

    NASA Astrophysics Data System (ADS)

    Bolton, Adam; SLACS; BELLS; SDSS-III

    2013-07-01

    Strong lensing offers the most direct method for constraining the distribution of mass in galaxies at cosmological distances. The combination of strong lensing with other observables increases its power, but often in ways that are model-dependent and resistant to intuition. In this talk, I will unpack the information content of spectroscopic, photometric, kinematic, and strong-lensing observables as they translate into constraints on the macroscopic distribution of luminous and dark matter in massive elliptical galaxies. I will also highlight how the choice of priors and analysis methods affects the conclusions drawn from a given set of observations. Finally, in this context I will present the latest results from observational efforts to extend strong-lensing analyses to lower mass galaxies in the Sloan Lens ACS Survey (SLACS) and to earlier cosmic times in the BOSS Emission-Line Lens Survey (BELLS).

  7. Measuring neutrino masses with weak lensing

    SciTech Connect

    Wong, Yvonne Y. Y.

    2006-11-17

    Weak gravitational lensing of distant galaxies by large scale structure (LSS) provides an unbiased way to map the matter distribution in the low redshift universe. This technique, based on the measurement of small distortions in the images of the source galaxies induced by the intervening LSS, is expected to become a key cosmological probe in the future. We discuss how future lensing surveys can probe the sum of the neutrino masses at the 0 05 eV level.

  8. Electron lenses for particle collimation in LHC

    SciTech Connect

    Shiltsev, v.; /Fermilab

    2007-12-01

    Electron Lenses built and installed in Tevatron have proven themselves as safe and very reliable instruments which can be effectively used in hadron collider operation for a number of applications, including compensation of beam-beam effects [1], DC beam removal from abort gaps [2], as a diagnostic tool. In this presentation we - following original proposal [3] - consider in more detail a possibility of using electron lenses with hollow electron beam for ion and proton collimation in LHC.

  9. Design and Development of Thin Plastic Foil, Conical Approximation, High Through-out X-Ray Telescope: Light Weight, Thin Plastic Foil, X-Ray Telescopes

    NASA Technical Reports Server (NTRS)

    Schnopper, Herbert W.; Barbera, Marco; Silver, Eric; Ingram, Russell; Christensen, Finn E.; Romaine, Suzanne; Cohen, Lester; Collura, Alfonso; Murray, Stephen S.; Brinton, John C. (Technical Monitor)

    2002-01-01

    We present results from a program to develop an X-ray telescope made from thin plastic shells. Our initial results have been obtained from multi-shell cylindrical lenses that are used in a point-to-point configuration to image the small focal spot of a an X-ray tube on a microchannel plate detector. We describe the steps that led up to the present design and present data from the tests that have been used to identify the properties of the plastic material that make it a suitable X-ray reflector. We discuss two applications of our technology to X-ray missions that are designed to address some of the scientific priorities set forth in NASA's long term plans for high energy astrophysics. One mission will observe in the 1 - 10 keV band, the other will extend up to ca. 100 keV.

  10. Ophthalmic glucose monitoring using disposable contact lenses.

    PubMed

    Geddes, Chris

    2004-01-01

    We have developed a range of disposable and colorless tear glucose sensing contact lenses, using off-the-shelf lenses embedded with new water soluble, highly fluorescent and glucose sensitive boronic acid containing fluorophores. The new lenses are readily able to track tear glucose levels and therefore blood glucose levels, which are ideally suited for potential use by diabetics. The fluorescence responses from the lenses can be monitored using simple excitation and emission detection devices. The novelty of our approach is two fold. Firstly, the notion of sensing extremely low glucose concentrations in tears, which track blood levels, by our contact lens approach, and secondly, the unique compatibility of our new glucose signaling probes with the internal mildly acidic contact lens environment. The new lenses are therefore ideal for the noninvasive and continuous monitoring of tear glucose, with a 15 minute response time, and a measured shelf life in excess of 3 months. In this invited article, we show that fluorescence based signaling using plastic disposable lenses, which have already been industrially optimized with regard to vision correction and oxygen / analyte permeability etc, may a notable alternative to invasive and random finger pricking, the most widely used glucose monitoring technology by diabetics. PMID:17271473

  11. Perspective projection camera model for zoom lenses

    NASA Astrophysics Data System (ADS)

    Willson, Reg G.; Shafer, Steven A.

    1994-03-01

    To effectively use automated zoom lenses for machine vision we need camera models that are valid over continuous ranges of lens settings. While camera calibration has been the subject of much research in machine vision and photogrammetry, for the most part the resulting models and calibration techniques have been for cameras with fixed parameter lenses where the lens' imaging process is static. For cameras with automated lenses the image formation process is a dynamic function of the lens control parameters. The complex nature of the relationships between the control parameters and the imaging process plus the need to calibrate them over a continuum of lens settings makes both the modeling and the calibration of cameras with automated zoom lenses fundamentally more difficult than that of cameras with fixed parameter lenses. In this paper we illustrate some of the problems involved with the modeling and calibration of cameras with variable parameter lenses. We then show how an iterative, empirical approach to modeling and calibration can produce a dynamic camera model of perspective projection that holds calibration across a continuous range of zoom.

  12. Cosmological test using strong gravitational lensing systems

    NASA Astrophysics Data System (ADS)

    Yuan, C. C.; Wang, F. Y.

    2015-09-01

    As one of the probes of universe, strong gravitational lensing systems allow us to compare different cosmological models and constrain vital cosmological parameters. This purpose can be reached from the dynamic and geometry properties of strong gravitational lensing systems, for instance, time-delay Δτ of images, the velocity dispersion σ of the lensing galaxies and the combination of these two effects, Δτ/σ2. In this paper, in order to carry out one-on-one comparisons between ΛCDM universe and Rh = ct universe, we use a sample containing 36 strong lensing systems with the measurement of velocity dispersion from the Sloan Lens Advanced Camera for Surveys (SLACS) and Lens Structure and Dynamic survey (LSD) survey. Concerning the time-delay effect, 12 two-image lensing systems with Δτ are also used. In addition, Monte Carlo simulations are used to compare the efficiency of the three methods as mentioned above. From simulations, we estimate the number of lenses required to rule out one model at the 99.7 per cent confidence level. Comparing with constraints from Δτ and the velocity dispersion σ, we find that using Δτ/σ2 can improve the discrimination between cosmological models. Despite the independence tests of these methods reveal a correlation between Δτ/σ2 and σ, Δτ/σ2 could be considered as an improved method of σ if more data samples are available.

  13. Wave propagation and phase retrieval in Fresnel diffraction by a distorted-object approach

    SciTech Connect

    Xiao Xianghui; Shen Qun

    2005-07-15

    An extension of the far-field x-ray diffraction theory is presented by the introduction of a distorted object for calculation of coherent diffraction patterns in the near-field Fresnel regime. It embeds a Fresnel-zone construction on an original object to form a phase-chirped distorted object, which is then Fourier transformed to form a diffraction image. This approach extends the applicability of Fourier-based iterative phasing algorithms into the near-field holographic regime where phase retrieval had been difficult. Simulated numerical examples of this near-field phase retrieval approach indicate its potential applications in high-resolution structural investigations of noncrystalline materials.

  14. Equatorial potassium currents in lenses.

    PubMed

    Wind, B E; Walsh, S; Patterson, J W

    1988-02-01

    Earlier work with the vibrating probe demonstrated the existence of outward potassium currents at the equator and inward sodium currents at the optical poles of the lens. By adding microelectrodes to the system, it is possible to relate steady currents (J) to the potential difference (PD) measured with a microelectrode. By injecting an outward current (I), it is possible to determine resistances and also the PD at which the steady outward potassium current becomes zero (PDJ = 0). At this PD the concentration gradient for potassium efflux and the electrical gradient for potassium influx are balanced so that there is no net flow of potassium across the membranes associated with the production of J. The PDJ = 0 for 18 rat lenses was 86 mV and that for 12 frogs lenses was -95 mV. This agrees with the potassium equilibrium potential and provides strong evidence to support the view that the outward equatorial current, J, is a potassium current. With the injection of outward current, I, the PD becomes more negative, the outward equatorial current, J, decreases, and the inward current at the optical poles increases. This suggests that there are separate electrical loops for K+ and Na+ that are partially linked by the Na, K-pump. Using Ohm's law, it is possible to calculate the input resistance (R = delta PD/I), the resistance related to the production of J (RJ = delta PD/delta J), and the effect of the combined resistances (delta J/I). The driving force for J can be estimated (PDJ = 0-PD). The relationships among currents, voltages and resistance can be used to determine the characteristics of the membranes that are associated with the outward potassium current observed at the equator. The effects of graded deformation of the lens were determined. The effects were reversible. The sites of inward and outward currents were not altered. Following deformation, the equatorial current, J, increased, and the PD became less negative. The PDJ = 0 remains the same so the ratio of K

  15. Surface Modification of Intraocular Lenses

    PubMed Central

    Huang, Qi; Cheng, George Pak-Man; Chiu, Kin; Wang, Gui-Qin

    2016-01-01

    Objective: This paper aimed to review the current literature on the surface modification of intraocular lenses (IOLs). Data Sources: All articles about surface modification of IOLs published up to 2015 were identified through a literature search on both PubMed and ScienceDirect. Study Selection: The articles on the surface modification of IOLs were included, but those on design modification and surface coating were excluded. Results: Technology of surface modification included plasma, ion beam, layer-by-layer self-assembly, ultraviolet radiation, and ozone. The main molecules introduced into IOLs surface were poly (ethylene glycol), polyhedral oligomeric silsesquioxane, 2-methacryloyloxyethyl phosphorylcholine, TiO2, heparin, F-heparin, titanium, titanium nitride, vinyl pyrrolidone, and inhibitors of cytokines. The surface modification either resulted in a more hydrophobic lens, a more hydrophilic lens, or a lens with a hydrophilic anterior and hydrophobic posterior surface. Advances in research regarding surface modification of IOLs had led to a better biocompatibility in both in vitro and animal experiments. Conclusion: The surface modification is an efficient, convenient, economic and promising method to improve the biocompatibility of IOLs. PMID:26830993

  16. Multifocal intraocular lenses and glare.

    PubMed

    Akutsu, H; Legge, G E; Luebker, A; Lindstrom, R L; Zabel, R W; Kirby, V M

    1993-06-01

    In a previous paper, we reported finding deficits in the contrast sensitivity functions of patients with diffractive multifocal intraocular lenses (IOL's). The results were consistent with optical measurements of the modulation transfer function (MTF) of the IOL. When this MTF is treated as a linear spatial frequency filter, it predicts the existence of a glare effect; contrast threshold for the recognition of target letters should be elevated by a bright, adjacent stimulus. We tested this prediction by measuring contrast thresholds for recognizing 0.2 degrees Sloan letters on a background luminance of 11.2 cd/m2. The letters were presented inside bright (300 cd/m2) annular rings with inner diameters ranging from 0.42 to 1.22 degrees. Thresholds were measured for seven multifocal subjects, age-matched groups of monofocal subjects and phakic-control subjects, and a young group. Multifocal subjects exhibited a greater glare effect than monofocal subjects, and they in turn exhibited a greater effect than phakic-control subjects. The observed glare effect for multifocal subjects was about twice that expected from the spatial filtering property of the multifocal IOL. PMID:8336911

  17. Molding aspheric lenses for low-cost production versus diamond turned lenses

    NASA Astrophysics Data System (ADS)

    Cogburn, Gabriel; Mertus, Louis; Symmons, Alan

    2010-04-01

    As lens design using aspheric diffractive lenses has become more popular in designing faster, low F/# infrared (IR) optical systems; the increased quantities manufactured of these glass lenses is following suit. Historically, Single Point Diamond Turning (SPDT) has been the method of choice in producing high quality glass aspheric and diffractive lenses, but with the volume of lenses produced and technological advances in Precision Molded Optics (PMO), it is now becoming highly cost efficient to use molding as a means of producing these glass optic lenses. This paper will discuss lens shapes, tolerances, present and future optic lens sizes that are being done using PMO as well as present an experiment conducted comparing the surface quality of a chalcogenide lens manufactured with SPDT and PMO.

  18. First measurement of the cross-correlation of CMB lensing and galaxy lensing

    NASA Astrophysics Data System (ADS)

    Hand, Nick; Leauthaud, Alexie; Das, Sudeep; Sherwin, Blake D.; Addison, Graeme E.; Bond, J. Richard; Calabrese, Erminia; Charbonnier, Aldée; Devlin, Mark J.; Dunkley, Joanna; Erben, Thomas; Hajian, Amir; Halpern, Mark; Harnois-Déraps, Joachim; Heymans, Catherine; Hildebrandt, Hendrik; Hincks, Adam D.; Kneib, Jean-Paul; Kosowsky, Arthur; Makler, Martin; Miller, Lance; Moodley, Kavilan; Moraes, Bruno; Niemack, Michael D.; Page, Lyman A.; Partridge, Bruce; Sehgal, Neelima; Shan, Huanyuan; Sievers, Jonathan L.; Spergel, David N.; Staggs, Suzanne T.; Switzer, Eric R.; Taylor, James E.; Van Waerbeke, Ludovic; Welker, Charlotte; Wollack, Edward J.

    2015-03-01

    We measure the cross-correlation of cosmic microwave background (CMB) lensing convergence maps derived from Atacama Cosmology Telescope data with galaxy lensing convergence maps as measured by the Canada-France-Hawaii Telescope Stripe 82 Survey. The CMB-galaxy lensing cross power spectrum is measured for the first time with a significance of 4.2 σ , which corresponds to a 12% constraint on the amplitude of density fluctuations at redshifts ˜0.9 . With upcoming improved lensing data, this novel type of measurement will become a powerful cosmological probe, providing a precise measurement of the mass distribution at intermediate redshifts and serving as a calibrator for systematic biases in weak lensing measurements.

  19. HerMES: CANDIDATE GRAVITATIONALLY LENSED GALAXIES AND LENSING STATISTICS AT SUBMILLIMETER WAVELENGTHS

    SciTech Connect

    Wardlow, Julie L.; Cooray, Asantha; De Bernardis, Francesco; Calanog, J.; Amblard, A.; Arumugam, V.; Aussel, H.; Bethermin, M.; Blundell, R.; Bussmann, R. S.; Bock, J.; Bridge, C.; Carpenter, J. M.; Boselli, A.; Buat, V.; Burgarella, D.; Cabrera-Lavers, A.; Castro-Rodriguez, N.; Casey, C. M.; and others

    2013-01-01

    We present a list of 13 candidate gravitationally lensed submillimeter galaxies (SMGs) from 95 deg{sup 2} of the Herschel Multi-tiered Extragalactic Survey, a surface density of 0.14 {+-} 0.04 deg{sup -2}. The selected sources have 500 {mu}m flux densities (S {sub 500}) greater than 100 mJy. Gravitational lensing is confirmed by follow-up observations in 9 of the 13 systems (70%), and the lensing status of the four remaining sources is undetermined. We also present a supplementary sample of 29 (0.31 {+-} 0.06 deg{sup -2}) gravitationally lensed SMG candidates with S {sub 500} = 80-100 mJy, which are expected to contain a higher fraction of interlopers than the primary candidates. The number counts of the candidate lensed galaxies are consistent with a simple statistical model of the lensing rate, which uses a foreground matter distribution, the intrinsic SMG number counts, and an assumed SMG redshift distribution. The model predicts that 32%-74% of our S {sub 500} {>=} 100 mJy candidates are strongly gravitationally lensed ({mu} {>=} 2), with the brightest sources being the most robust; this is consistent with the observational data. Our statistical model also predicts that, on average, lensed galaxies with S {sub 500} = 100 mJy are magnified by factors of {approx}9, with apparently brighter galaxies having progressively higher average magnification, due to the shape of the intrinsic number counts. 65% of the sources are expected to have intrinsic 500 {mu}m flux densities less than 30 mJy. Thus, samples of strongly gravitationally lensed SMGs, such as those presented here, probe below the nominal Herschel detection limit at 500 {mu}m. They are good targets for the detailed study of the physical conditions in distant dusty, star-forming galaxies, due to the lensing magnification, which can lead to spatial resolutions of {approx}0.''01 in the source plane.

  20. Observation of lasing modes with exotic localized wave patterns from astigmatic large-Fresnel-number cavities.

    PubMed

    Lu, T H; Lin, Y C; Liang, H C; Huang, Y J; Chen, Y F; Huang, K F

    2010-02-01

    We investigate the lasing modes in large-Fresnel-number laser systems with astigmatism effects. Experimental results reveal that numerous lasing modes are concentrated on exotic patterns corresponding to intriguing geometries. We theoretically use the quantum operator algebra to construct the wave representation for manifesting the origin of the localized wave patterns. PMID:20125716

  1. A Modified Version of Young's Interferometer to Study the Fresnel and Arago Interference Laws

    ERIC Educational Resources Information Center

    Kanseri, Bashkar; Bisht, Nandan S.; Rath, Shyama; Kandpal, H. C.

    2009-01-01

    We present a modified version of Young's interferometer to verify experimentally the four interference laws propounded by Fresnel and Arago. Theoretical analysis is given using the complex algebra and the matrix representation for polarizers, rotators and the electromagnetic field. The advantage of the modified interferometer over other spatial…

  2. 26. Photograph of original Fresnel lens a 1st order fixed ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. Photograph of original Fresnel lens a 1st order fixed white light. (Installed 1874 and first illuminated Feb. 1, 1875. This is the only known photograph of this lens - - removed in 1929.)ca. 1918. - Block Island Southeast Light, Spring Street & Mohegan Trail at Mohegan Bluffs, New Shoreham, Washington County, RI

  3. Optical sectioning using a digital Fresnel incoherent-holography-based confocal imaging system

    PubMed Central

    Kelner, Roy; Katz, Barak; Rosen, Joseph

    2015-01-01

    We propose a new type of confocal microscope using Fresnel incoherent correlation holography (FINCH). Presented here is a confocal configuration of FINCH using a phase pinhole and point illumination that is able to suppress out-of-focus information from the recorded hologram and hence combine the super-resolution capabilities of FINCH with the sectioning capabilities of confocal microscopy. PMID:26413560

  4. Fully phase multiple information encoding based on superposition of two beams and Fresnel-transform domain

    NASA Astrophysics Data System (ADS)

    Abuturab, Muhammad Rafiq

    2015-12-01

    A novel asymmetric multiple information encoding using superposition of two beams and Fresnel transform, is proposed. In this scheme, each channel of individual user image is separately phase encoded and then modulated by random phase mask. The three modulated user channels are independently multiplied to produce three complex user channels. They are individually multiplied with three channels of carrier image and Fresnel transformed, and then phase- and amplitude truncated to produce first set of three encrypted channels and three asymmetric keys. Now each channel of secret image is normalized, phase-only masked, and then independently multiplied by corresponding modulated user channels. The three resultant channels are separately multiplied to construct three complex secret channels. Afterward, the three encrypted channels are multiplied with corresponding three complex secret channels and Fresnel transformed, and then phase- and amplitude truncated to obtain second set of three encrypted channels and three asymmetric keys. The wavelengths and propagation distances of two Fresnel transforms, and two asymmetric keys are common keys to all authorized-users, while two individual keys are provided to each authorized-user. The encryption process is implemented digitally while the decryption process can be performed optoelectronically. The proposed method is asymmetric, noniterative and larger multiplexing capacity without any cross-talk noise effects. Owing to the individual user image based method, high robustness against existing attacks can be achieved. Numerical simulation results demonstrate that the proposed method is feasible and efficient.

  5. Aerogel detector with a Fresnel lens focalization: a test of the concept

    SciTech Connect

    Sokolov, O.; Paic, G.; Alfaro, R.

    2008-07-02

    We present a threshold aerogel detector that uses only the unscattered light in the aerogel, focused on a photomultiplier using a Fresnel lens. The results with n = 1.03 and 3'' photomultiplier are presented. The possibility to use 1.5'' PMT is discussed.

  6. Scintillations during occultations by planets. 1. An approximate theory. [fresnel region

    NASA Technical Reports Server (NTRS)

    Young, A. T.

    1975-01-01

    Scintillations observed during occultations of both stars and spacecraft by planetary atmospheres are discussed theoretically. The effects of severe flattening of the Fresnel zone or source image by defocusing on occultations are presented, along with temporal power spectra. Other topics discussed include atmospheric turbulence, saturation of scintillation, effects of saturation on occultation curves, and some methods for a more accurate determination of atmospheric structure.

  7. Enhanced-resolution using modified configuration of Fresnel incoherent holographic recorder with synthetic aperture

    PubMed Central

    Kashter, Yuval; Rosen, Joseph

    2014-01-01

    Synthetic aperture methods are commonly-used techniques for providing images with super-resolution qualities. We propose an improved design of the system, coined “synthetic aperture with Fresnel elements”. The super-resolution capabilities of the proposed scheme are analyzed and experimentally demonstrated. PMID:25321260

  8. Pixelation Effects in Weak Lensing

    NASA Technical Reports Server (NTRS)

    High, F. William; Rhodes, Jason; Massey, Richard; Ellis, Richard

    2007-01-01

    Weak gravitational lensing can be used to investigate both dark matter and dark energy but requires accurate measurements of the shapes of faint, distant galaxies. Such measurements are hindered by the finite resolution and pixel scale of digital cameras. We investigate the optimum choice of pixel scale for a space-based mission, using the engineering model and survey strategy of the proposed Supernova Acceleration Probe as a baseline. We do this by simulating realistic astronomical images containing a known input shear signal and then attempting to recover the signal using the Rhodes, Refregier, and Groth algorithm. We find that the quality of shear measurement is always improved by smaller pixels. However, in practice, telescopes are usually limited to a finite number of pixels and operational life span, so the total area of a survey increases with pixel size. We therefore fix the survey lifetime and the number of pixels in the focal plane while varying the pixel scale, thereby effectively varying the survey size. In a pure trade-off for image resolution versus survey area, we find that measurements of the matter power spectrum would have minimum statistical error with a pixel scale of 0.09' for a 0.14' FWHM point-spread function (PSF). The pixel scale could be increased to 0.16' if images dithered by exactly half-pixel offsets were always available. Some of our results do depend on our adopted shape measurement method and should be regarded as an upper limit: future pipelines may require smaller pixels to overcome systematic floors not yet accessible, and, in certain circumstances, measuring the shape of the PSF might be more difficult than those of galaxies. However, the relative trends in our analysis are robust, especially those of the surface density of resolved galaxies. Our approach thus provides a snapshot of potential in available technology, and a practical counterpart to analytic studies of pixelation, which necessarily assume an idealized shape

  9. Pixelation Effects in Weak Lensing

    NASA Astrophysics Data System (ADS)

    High, F. William; Rhodes, Jason; Massey, Richard; Ellis, Richard

    2007-11-01

    Weak gravitational lensing can be used to investigate both dark matter and dark energy but requires accurate measurements of the shapes of faint, distant galaxies. Such measurements are hindered by the finite resolution and pixel scale of digital cameras. We investigate the optimum choice of pixel scale for a space-based mission, using the engineering model and survey strategy of the proposed Supernova Acceleration Probe as a baseline. We do this by simulating realistic astronomical images containing a known input shear signal and then attempting to recover the signal using the Rhodes, Refregier, & Groth algorithm. We find that the quality of shear measurement is always improved by smaller pixels. However, in practice, telescopes are usually limited to a finite number of pixels and operational life span, so the total area of a survey increases with pixel size. We therefore fix the survey lifetime and the number of pixels in the focal plane while varying the pixel scale, thereby effectively varying the survey size. In a pure trade-off for image resolution versus survey area, we find that measurements of the matter power spectrum would have minimum statistical error with a pixel scale of 0.09" for a 0.14" FWHM point-spread function (PSF). The pixel scale could be increased to ~0.16" if images dithered by exactly half-pixel offsets were always available. Some of our results do depend on our adopted shape measurement method and should be regarded as an upper limit: future pipelines may require smaller pixels to overcome systematic floors not yet accessible, and, in certain circumstances, measuring the shape of the PSF might be more difficult than those of galaxies. However, the relative trends in our analysis are robust, especially those of the surface density of resolved galaxies. Our approach thus provides a snapshot of potential in available technology, and a practical counterpart to analytic studies of pixelation, which necessarily assume an idealized shape

  10. Plasma lenses for focusing relativistic electron beams

    SciTech Connect

    Govil, R.; Wheeler, S.; Leemans, W.

    1997-04-01

    The next generation of colliders require tightly focused beams with high luminosity. To focus charged particle beams for such applications, a plasma focusing scheme has been proposed. Plasma lenses can be overdense (plasma density, n{sub p} much greater than electron beam density, n{sub b}) or underdense (n{sub p} less than 2 n{sub b}). In overdense lenses the space-charge force of the electron beam is canceled by the plasma and the remaining magnetic force causes the electron beam to self-pinch. The focusing gradient is nonlinear, resulting in spherical aberrations. In underdense lenses, the self-forces of the electron beam cancel, allowing the plasma ions to focus the beam. Although for a given beam density, a uniform underdense lens produces smaller focusing gradients than an overdense lens, it produces better beam quality since the focusing is done by plasma ions. The underdense lens can be improved by tapering the density of the plasma for optimal focusing. The underdense lens performance can be enhanced further by producing adiabatic plasma lenses to avoid the Oide limit on spot size due to synchrotron radiation by the electron beam. The plasma lens experiment at the Beam Test Facility (BTF) is designed to study the properties of plasma lenses in both overdense and underdense regimes. In particular, important issues such as electron beam matching, time response of the lens, lens aberrations and shot-to-shot reproducibility are being investigated.

  11. Evaluation of the Quality of Action Cameras with Wide-Angle Lenses in Uav Photogrammetry

    NASA Astrophysics Data System (ADS)

    Hastedt, H.; Ekkel, T.; Luhmann, T.

    2016-06-01

    The application of light-weight cameras in UAV photogrammetry is required due to restrictions in payload. In general, consumer cameras with normal lens type are applied to a UAV system. The availability of action cameras, like the GoPro Hero4 Black, including a wide-angle lens (fish-eye lens) offers new perspectives in UAV projects. With these investigations, different calibration procedures for fish-eye lenses are evaluated in order to quantify their accuracy potential in UAV photogrammetry. Herewith the GoPro Hero4 is evaluated using different acquisition modes. It is investigated to which extent the standard calibration approaches in OpenCV or Agisoft PhotoScan/Lens can be applied to the evaluation processes in UAV photogrammetry. Therefore different calibration setups and processing procedures are assessed and discussed. Additionally a pre-correction of the initial distortion by GoPro Studio and its application to the photogrammetric purposes will be evaluated. An experimental setup with a set of control points and a prospective flight scenario is chosen to evaluate the processing results using Agisoft PhotoScan. Herewith it is analysed to which extent a pre-calibration and pre-correction of a GoPro Hero4 will reinforce the reliability and accuracy of a flight scenario.

  12. Commercial Development of an Advanced, High-Temperature, Linear-Fresnel Based Concentrating Solar Power Concept

    SciTech Connect

    Viljoen, Nolan; Schuknecht, Nathan

    2012-05-28

    Included herein is SkyFuel’s detailed assessment of the potential for a direct molten salt linear Fresnel collector. Linear Fresnel architecture is of interest because it has features that are well suited for use with molten salt as a heat transfer fluid: the receiver is fixed (only the mirrors track), the receiver diameter is large (reducing risk of freeze events), and the total linear feet of receiver can be reduced due to the large aperture area. Using molten salt as a heat transfer fluid increases the allowable operating temperature of a collector field, and the cost of thermal storage is reduced in proportion to that increase in temperature. At the conclusion of this project, SkyFuel determined that the cost goals set forth in the contract could not be reasonably met. The performance of a Linear Fresnel collector is significantly less than that of a parabolic trough, in particular due to linear Fresnel’s large optical cosine losses. On an annual basis, the performance is 20 to 30% below that of a parabolic trough per unit area. The linear Fresnel collector and balance of system costs resulted in an LCOE of approximately 9.9¢/kWhre. Recent work by SkyFuel has resulted in a large aperture trough design (DSP Trough) with an LCOE value of 8.9 ¢/kWhre calculated with comparative financial terms and balance of plant costs (White 2011). Thus, even though the optimized linear Fresnel collector of our design has a lower unit cost than our optimized trough, it cannot overcome the reduction in annual performance.

  13. Gravitational lensing statistics of amplified supernovae

    NASA Technical Reports Server (NTRS)

    Linder, Eric V.; Wagoner, Robert V.; Schneider, P.

    1988-01-01

    Amplification statistics of gravitationally lensed supernovae can provide a valuable probe of the lensing matter in the universe. A general probability distribution for amplification by compact objects is derived which allows calculation of the lensed fraction of supernovae at or greater than an amplification A and at or less than an apparent magnitude. Comparison of the computed fractions with future results from ongoing supernova searches can lead to determination of the mass density of compact dark matter components with masses greater than about 0.001 solar mass, while the time-dependent amplification (and polarization) of the expanding supernovae constrain the individual masses. Type II supernovae are found to give the largest fraction for deep surveys, and the optimum flux-limited search is found to be at approximately 23d magnitude, if evolution of the supernova rate is neglected.

  14. Functionalized patchy particles using colloidal lenses

    NASA Astrophysics Data System (ADS)

    Middleton, Christine

    2014-03-01

    Colloidal assembly had been limited by the isotropic, nonspecific nature of interactions between spherical colloidal particles. By giving particles patches functionalized with single stranded DNA, these interactions can be made both directional and specific. We create patchy particles by adding patches to spherical emulsion droplets using the depletion interaction. First we make polystyrene particles in the shape of contact lenses to be the patches. The lenses are functionalized with single stranded DNA on their convex side. Then we put the lenses on the surface of oil emulsion droplets using the depletion interaction, creating a patch (or multiple patches) on the surface of each emulsion droplet. The emulsion droplets can now interact with each other in a specific, directional way through DNA functionalized patches.

  15. Weak lensing in the Dark Energy Survey

    NASA Astrophysics Data System (ADS)

    Troxel, Michael

    2016-03-01

    I will present the current status of weak lensing results from the Dark Energy Survey (DES). DES will survey 5000 square degrees in five photometric bands (grizY), and has already provided a competitive weak lensing catalog from Science Verification data covering just 3% of the final survey footprint. I will summarize the status of shear catalog production using observations from the first year of the survey and discuss recent weak lensing science results from DES. Finally, I will report on the outlook for future cosmological analyses in DES including the two-point cosmic shear correlation function and discuss challenges that DES and future surveys will face in achieving a control of systematics that allows us to take full advantage of the available statistical power of our shear catalogs.

  16. 'Colored' and Decorative Contact Lenses: A Prescription Is a Must

    MedlinePlus

    ... labeling. (See additional information about cleaning solutions with hydrogen peroxide on the FDA website.) See your eye ... For More Information Decorative Contact Lenses Contact Lenses Hydrogen Peroxide Solution Related Consumer Updates Focusing on Contact ...

  17. What To Know If Your Child Wants Contact Lenses

    MedlinePlus

    ... For More Information Decorative Contact Lenses Contact Lenses Hydrogen Peroxide Solution Consumer Updates Focusing on Contact Lens ... Prescription Is A Must Contact Lens Solutions With Hydrogen Peroxide: To Avoid Injury, Follow All Instructions Five ...

  18. Research and analysis on new test lenses for calibration of focimeters used for measuring contact lenses

    NASA Astrophysics Data System (ADS)

    Zhang, Jiyan; Wang, Liru; Ma, Zhenya

    2006-11-01

    A focimeter is one of the basic ophthalmic instruments used in every optometric practice, and verification of the accuracy and calibration of the instrument are of the utmost importance. For many years the International Standardization for Organization requires that calibrations for all kinds of focimeters shall be accomplished by using test lenses described in ISO 9342:1996. These test lenses must be of high quality and of nominal back vertex power that is known with high accuracy. With the development of science and technology, ISO 9342 was revised in 2005. A new part ISO 9342-2 had been drafted for test lenses used to calibrate focimeters with contact lens measurement, and the original ISO 9342 was turned into the current ISO 9342-1, which could only be used to calibrate fociemters with spectacle lens measurement. As one of the standard drafters, the background for the newly published ISO 9342-2 is introduced in this study, and comparison between test lenses of ISO 9342-1 and ISO 9342-2 is made. Further, the influence of tolerance and uncertainty in design and production of standard test lenses of ISO 9342-2 is analyzed. The paraxial approximation is used to relate the lens parameters with back vertex power and to calculate the uncertainty budget. Moreover, one set of test lenses conforming to ISO 9342-2 is manufactured and experiments are done with it. Results show that test lenses described in ISO 9342-2 can correct the measurement errors of focimeters used for measuring contact lenses well, especially for spherical aberration, and the correction is more effective for spherical contact lenses with high back vertex power.

  19. Durability of Poly(Methyl Methacrylate) Lenses Used in Concentrating Photovoltaic Modules: Preprint

    SciTech Connect

    Miller, D. C.; Gedvilas, L. M.; To, B.; Kennedy, C. E.; Kurtz, S. R.

    2010-08-01

    Concentrating photovoltaic (CPV) technology has recently gained interest based on their expected low levelized cost of electricity, high efficiency, and scalability. Many CPV systems use Fresnel lenses made of poly(methyl methacrylate)(PMMA) to obtain a high optical flux density. The optical and mechanical durability of such components, however, are not well established relative to the desired service life of 30 years. Specific reliability issues may include: reduced optical transmittance, discoloration, hazing, surface erosion, embrittlement, crack growth, physical aging, shape setting (warpage), and soiling. The initial results for contemporary lens- and material-specimens aged cumulatively to 6 months are presented. The study here uses an environmental chamber equipped with a xenon-arc lamp to age specimens at least 8x the nominal field rate. A broad range in the affected characteristics (including optical transmittance, yellowness index, mass loss, and contact angle) has been observed to date, depending on the formulation of PMMA used. The most affected specimens are further examined in terms of their visual appearance, surface roughness (examined via atomic force microscopy), and molecular structure (via Fourier transform infrared spectroscopy).

  20. Durability of poly(methyl methacrylate) lenses used in concentrating photovoltaic modules

    NASA Astrophysics Data System (ADS)

    Miller, David C.; Gedvilas, Lynn M.; To, Bobby; Kennedy, Cheryl E.; Kurtz, Sarah R.

    2010-08-01

    Concentrating photovoltaic (CPV) technology has recently gained interest based on their expected low levelized cost of electricity, high efficiency, and scalability. Many CPV systems use Fresnel lenses made of poly(methyl methacrylate) (PMMA) to obtain a high optical flux density. The optical and mechanical durability of such components, however, are not well established relative to the desired service life of 30 years. Specific reliability issues may include: reduced optical transmittance, discoloration, hazing, surface erosion, embrittlement, crack growth, physical aging, shape setting (warpage), and soiling. The initial results for contemporary lens- and material-specimens aged cumulatively to 6 months are presented. The study here uses an environmental chamber equipped with a xenon-arc lamp to age specimens at least 8x the nominal field rate. A broad range in the affected characteristics (including optical transmittance, yellowness index, mass loss, and contact angle) has been observed to date, depending on the formulation of PMMA used. The most affected specimens are further examined in terms of their visual appearance, surface roughness (examined via atomic force microscopy), and molecular structure (via Fourier transform infrared spectroscopy).

  1. SARCS strong-lensing galaxy groups. II. Mass-concentration relation and strong-lensing bias

    NASA Astrophysics Data System (ADS)

    Foëx, G.; Motta, V.; Jullo, E.; Limousin, M.; Verdugo, T.

    2014-12-01

    Aims: Various studies have shown a lensing bias in the mass-concentration relation of cluster-scale structures that is the result of an alignment of the major axis and the line of sight. In this paper, we aim to study this lensing bias through the mass-concentration relation of galaxy groups, thus extending observational constraints to dark matter haloes of mass ~1013-1014 M⊙. Methods: Our work is based on the stacked weak-lensing analysis of a sample of 80 strong-lensing galaxy groups. By combining several lenses, we significantly increase the signal-to-noise ratio of the lensing signal, thus providing constraints on the mass profile that cannot be obtained for individual objects. The resulting shear profiles were fitted with various mass models, among them the Navarro-Frank-White (NFW) profile, which provides an estimate of the total mass and of the concentration of the composite galaxy groups. Results: The main results of our analysis are the following: (i) the lensing signal does not allow us to firmly distinguish between a simple singular isothermal sphere mass distribution and the expected NFW mass profile; (ii) we obtain an average concentration c200 = 8.6-1.3+2.1 that is much higher than the value expected from numerical simulations for the corresponding average mass M200 = 0.73-0.10+0.11 × 1014 M⊙; (iii) the combination of our results with those at larger mass scales gives a mass-concentration relation c(M) of more than two decades in mass, whose slope disagrees with predictions from numerical simulations using unbiased populations of dark matter haloes; (iv) our combined c(M) relation matches results from simulations that only used haloes with a large strong-lensing cross-section, that is, elongated with a major axis close to the line of sight; (v) for the simplest case of prolate haloes, we estimate a lower limit on the minor-to-major axis ratio a/c = 0.5 for the average SARCS galaxy group with a toy model. Conclusions: Our analysis based on galaxy

  2. Gravitational lensing by straight cosmic strings

    NASA Astrophysics Data System (ADS)

    Kotvytskiy, A. T.

    2015-07-01

    We consider effects due to gravitational lensing by hypothetical cosmic strings. We briefly review facts concerning infinite straight strings, obtain the equation for a gravitational lens produced by an infinite string in the classical form, and analyze features of the gravitational lensing for a given object in detail. We consider a finite straight string. We present caustics and critical curves for strings with different lengths and also some images produced by the considered gravitational lens. We propose a method for constructing brightness curves numerically. As an example of the working capacity of this method, we construct a concrete brightness curve for certain gravitational lens parameters.

  3. Achromatic Cooling Channel with Li Lenses

    SciTech Connect

    Balbekov, V.

    2002-04-29

    A linear cooling channel with Li lenses, solenoids, and 201 MHz RF cavities is considered. A special lattice design is used to minimize chromatic aberrations by suppression of several betatron resonances. Transverse emittance of muon beam decreases from 2 mm to 0.5 mm at the channel of about 110 m length. Longitudinal heating is modest, therefore transmission of the channel is rather high: 96% without decay and 90% with decay. Minimal beam emittance achievable by similar channel estimated as about 0.25 mm at surface field of Li lenses 10 T.

  4. Cosmic string lensing and closed timelike curves

    NASA Astrophysics Data System (ADS)

    Shlaer, Benjamin; Tye, S.-H. Henry

    2005-08-01

    In an analysis of the gravitational lensing by two relativistic cosmic strings, we argue that the formation of closed timelike curves proposed by Gott is unstable in the presence of particles (e.g. the cosmic microwave background radiation). Because of the attractorlike behavior of the closed timelike curve, we argue that this instability is very generic. A single graviton or photon in the vicinity, no matter how soft, is sufficient to bend the strings and prevent the formation of closed timelike curves. We also show that the gravitational lensing due to a moving cosmic string is enhanced by its motion, not suppressed.

  5. The Design And Performance Of Aspheric Ophthalmic Lenses.

    NASA Astrophysics Data System (ADS)

    Smith, G.

    1986-05-01

    The significant aberrations in ophthalmic lenses are (oblique) astigmatism (spectacle lenses) and spherical aberration (contact and intra-ocular lenses). In many cases, they cannot be eliminated or sufficiently controlled by bending. Fortunately, aspherizing one or both surfaces allows much greater control over either of these aberrations and in the case of contact and intra-ocular lenses, allows the balancing of the spherical aberration in the eye itself.

  6. A new method to validate the usage of Fresnel approximation instead of Kirchhoff diffraction formula for calculations concerning camera systems

    NASA Astrophysics Data System (ADS)

    Talbiersky, Ulrike

    2010-05-01

    The usage of Fresnel diffraction as an approximation of the Kirchhoff formula offers a large variety of advantages concerning diverse calculations for camera systems. However, Fresnel approximations cannot be applied to arbitrary camera systems. For configurations with wide aperture, e.g., the usage of Fresnel approximation is not possible without accepting an unagreeable deviation. It is important to check in advance if a camera system allows such an approximation for the needed calculations. Assuming that focal length f and ground distance g are given quantities, investigations of the real and complex integrands lead to a formula from which the minimal F-number f# (respectively the maximum aperture radius r) is derived, so that Fresnel approximations can still be applied to a system. The analytical results are supported by numerical calculations and audited for three camera configurations outlined for remote sensing.

  7. Electron Lenses for the Large Hadron Collider

    SciTech Connect

    Stancari, Giulio; Valishev, Alexander; Bruce, Roderik; Redaelli, Stefano; Rossi, Adriana; Salvachua, Belen

    2014-07-01

    Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-by-bunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beam compensation, and for the demonstration of halo scraping with hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in RHIC at BNL. Within the US LHC Accelerator Research Program and the European HiLumi LHC Design Study, hollow electron beam collimation was studied as an option to complement the collimation system for the LHC upgrades. This project is moving towards a technical design in 2014, with the goal to build the devices in 2015-2017, after resuming LHC operations and re-assessing needs and requirements at 6.5 TeV. Because of their electric charge and the absence of materials close to the proton beam, electron lenses may also provide an alternative to wires for long-range beam-beam compensation in LHC luminosity upgrade scenarios with small crossing angles.

  8. SUNGLASS: A Weak-lensing Simulation Pipeline

    NASA Astrophysics Data System (ADS)

    Kiessling, Alina; Taylor, A.; Heavens, A.; Rhodes, J.; Bartlett, J.

    2013-01-01

    Weak gravitational lensing analysis is a powerful tool to investigate the dark Universe. Next generation weak-lensing telescope surveys (e.g. Euclid and WFIRST) promise to determine the equation of state of dark energy to 1% as well as probing the possibilities of extra dimensional gravity models and alternative cosmologies. To realize the potential of these new telescope surveys and to test new weak-lensing analysis techniques, challenges must be met. To achieve the small statistical errors required, experiments require full end-to-end simulations of huge volumes, which also probe the non-linear regime to assist in understanding the limitations of the analysis techniques. We have developed a new cosmic shear analysis pipeline SUNGLASS (Simulated UNiverses for Gravitational Lensing Analysis and Shear Surveys) that rapidly generates cosmic shear and convergence catalogues using N-body simulations. In this poster, I introduce the SUNGLASS pipeline and show how the SUNGLASS mock shear catalogues can be used in preparation for upcoming telescope missions and for analysis of existing observational data sets.

  9. Zoom microscope objective using electrowetting lenses.

    PubMed

    Li, Lei; Wang, Di; Liu, Chao; Wang, Qiong-Hua

    2016-02-01

    We report a zoom microscope objective which can achieve continuous zoom change and correct the aberrations dynamically. The objective consists of three electrowetting liquid lenses and two glass lenses. The magnification is changed by applying voltages on the three electrowetting lenses. Besides, the three electrowetting liquid lenses can play a role to correct the aberrations. A digital microscope based on the proposed objective is demonstrated. We analyzed the properties of the proposed objective. In contrast to the conventional objectives, the proposed objective can be tuned from ~7.8 × to ~13.2 × continuously. For our objective, the working distance is fixed, which means no movement parts are needed to refocus or change its magnification. Moreover, the zoom objective can be dynamically optimized for a wide range of wavelength. Using such an objective, the fabrication tolerance of the optical system is larger than that of a conventional system, which can decrease the fabrication cost. The proposed zoom microscope objective cannot only take place of the conventional objective, but also has potential application in the 3D microscopy. PMID:26906860

  10. Teaching the Theory of Real Lenses.

    ERIC Educational Resources Information Center

    Walther, A.

    1996-01-01

    Presents an approach to the study of real lenses that would not contradict Fermat's principle. Shows how the rudiments of the correct theory can be incorporated into courses to provide students a clearer notion of what they can expect in laboratory situations. (DDR)

  11. Software for Fermat's principle and lenses

    NASA Astrophysics Data System (ADS)

    Mihas, Pavlos

    2012-05-01

    Fermat's principle is considered as a unifying concept. It is usually presented erroneously as a 'least time principle'. In this paper we present some software that shows cases of maxima and minima and the application of Fermat's principle to the problem of focusing in lenses.

  12. Software for Fermat's Principle and Lenses

    ERIC Educational Resources Information Center

    Mihas, Pavlos

    2012-01-01

    Fermat's principle is considered as a unifying concept. It is usually presented erroneously as a "least time principle". In this paper we present some software that shows cases of maxima and minima and the application of Fermat's principle to the problem of focusing in lenses. (Contains 12 figures.)

  13. Formation of Lenses by Liquid Interfacial Surfaces

    NASA Astrophysics Data System (ADS)

    Zimmerman, Charlotte; Cerjan, Benjamin; Baylor, Martha-Elizabeth

    2013-03-01

    In this study, we examined the geometry of polymer lenses formed by liquid interfacial surfaces. We formed lenses by dropping hydrophobic photo-curable monomer on the surface of various hydrophilic liquid substrates. Due to intermolecular forces between the monomer and the substrate liquid, the interface is pulled into a curved shape. Upon exposure to UV light, the monomer solidifies while maintaining the boundary interface. The result is a plano-convex, optically-smooth polymer lens. The interfacial surface tension is manipulated by altering the amount of thin film present on the surface of the hydrophilic liquid, producing lenses of different curvatures. The lens curvature is further modified by using various salts that change the polarity of the substrate solution. We will present data demonstrating modification of the lens shape due to specific changes made to the physical and chemical properties of the hydrophilic liquid. We believe this liquid interfacial fabrication technique offers an alternative to current molding techniques for forming polymer lenses.

  14. Strong Lensing Mass Reconstruction: from Frontier Fields to the Typical Lensing Clusters of Future Surveys

    NASA Astrophysics Data System (ADS)

    Sharon, Keren

    2015-08-01

    Driven by the unprecedented wealth of high quality data that is accumulating for the Frontier Fields, they are becoming some of the best-studied strong lensing clusters to date, and probably the next few years. As will be discussed intensively in this focus meeting, the FF prove transformative for many fields: from studies of the high redshift Universe, to the assembly and structure of the clusters themselves. The FF data and the extensive collaborative effort around this program will also allow us to examine and improve upon current lens modeling techniques. Strong lensing is a powerful tool for mass reconstruction of the cores of galaxy clusters of all scales, providing an estimate of the total (dark and seen) projected mass density distribution out to ~0.5 Mpc. Though SL mass may be biased by contribution from structures along the line of sight, its strength is that it is relatively insensitive to assumptions on cluster baryon astrophysics and dynamical state. Like the Frontier Fields clusters, the most "famous" strong lensing clusters are at the high mass end; they lens dozens of background sources into multiple images, providing ample lensing constraints. In this talk, I will focus on how we can leverage what we learn from modeling the FF clusters in strong lensing studies of the hundreds of clusters that will be discovered in upcoming surveys. In typical clusters, unlike the Frontier Fields, the Bullet Cluster and A1689, we observe only one to a handful of background sources, and have limited lensing constraints. I will describe the limitations that such a configuration imposes on strong lens modeling, highlight measurements that are robust to the richness of lensing evidence, and address the sources of uncertainty and what sort of information can help reduce those uncertainties. This category of lensing clusters is most relevant to the wide cluster surveys of the future.

  15. Compound lensing: Einstein zig-zags and high-multiplicity lensed images

    NASA Astrophysics Data System (ADS)

    Collett, Thomas E.; Bacon, David J.

    2016-02-01

    Compound strong gravitational lensing is a rare phenomenon, but a handful of such lensed systems are likely to be discovered in forthcoming surveys. In this work, we use a double singular isothermal sphere lens model to analytically understand how the properties of the system impact image multiplicity for the final source. We find that up to six images of a background source can form, but only if the second lens is multiply imaged by the first and the Einstein radius of the second lens is comparable to, but does not exceed that of the first. We then build a model of compound lensing masses in the Universe, using singular isothermal ellipsoid (SIE) lenses, and assess how the optical depth for multiple imaging by a galaxy-galaxy compound lens varies with source redshift. For a source redshift of 4, we find optical depths of 6 × 10-6 for multiple imaging and 5 × 10-8 for multiplicity of 6 or greater. We find that extreme magnifications are possible, with magnifications of 100 or more for 6 × 10-9 of z = 10 sources with 0.1 kpc radii. We show some of the image configurations that can be generated by compound lenses, and demonstrate that they are qualitatively different to those generated by single-plane lenses; dedicated compound lens finders will be necessary if these systems are to be discovered in forthcoming surveys.

  16. Terahertz lenses made by compression molding of micropowders.

    PubMed

    Scherger, Benedikt; Scheller, Maik; Jansen, Christian; Koch, Martin; Wiesauer, Karin

    2011-05-20

    We present a simple and versatile approach for fabricating terahertz lenses based on compression molding of micropowder polymer materials in a tabletop hydraulic press. To demonstrate the feasibility of this approach, a biconvex lens shape is calculated using a ray-tracing algorithm and lenses based on two different micropowders are fabricated. As the powder materials have different refractive indices, the resulting lenses share the same geometric shape but differ in their respective focal length. The focusing properties of the lenses are evaluated by transversal and sagittal beam profile measurements in a fiber-coupled terahertz time-domain spectroscopy system, confirming the excellent imaging qualities of the compression molded lenses. PMID:21614120

  17. Experimental and numerical studies on the issues in laser welding of light-weight alloys in a zero-gap lap joint configuration

    NASA Astrophysics Data System (ADS)

    Harooni, Masoud

    current study a non-destructive evaluation method based on spectroscopy is proposed to detect the presence of pores in the lap joint of laser welded AZ31B magnesium alloy. The electron temperature that is calculated by the Boltzmann plot method is correlated to the presence of pores in the weld bead. A separate series of experiments was performed to evaluate the effect of an oxide coating layer on the dynamic behavior of the molten pool in the laser welding of an AZ31B magnesium alloy in a zero-gap lap joint configuration. A high speed CCD camera assisted with a green laser as an illumination source was selected to record the weld pool dynamics. Another technique used in this study was two-pass laser welding process to join AZ31B magnesium sheet in a zero-gap, lap-shear configuration. Two groups of samples including one pass laser welding (OPLW) and two pass laser welding (TPLW) were studied. In the two pass laser welding procedure, the first pass is performed by a defocused laser beam on the top of the two overlapped sheets in order to preheat the faying surface prior to laser welding, while the second pass is applied to melt and eventually weld the samples. Tensile and microhardness tests were used to measure the mechanical properties of the laser welded samples. A spectrometer was also used in real-time to correlate pore formation with calculated electron temperature using the Boltzmann plot method. The results of calculated electron temperature confirmed the previous results in earlier chapter. Magnesium and aluminum are two alloys which are used in different industries mainly due to their light weight. The main use of these two alloys is in automotive industry. Since different parts of the automobiles can be manufactured with each of these two alloys, it is essential to evaluate the joining feasibility of dissimilar metals such as aluminum to magnesium. A 4 kW fiber laser is used to join AZ31B magnesium alloy to AA 6014 using an overlap joint configuration. Two

  18. Experimental and numerical studies on the issues in laser welding of light-weight alloys in a zero-gap lap joint configuration

    NASA Astrophysics Data System (ADS)

    Harooni, Masoud

    current study a non-destructive evaluation method based on spectroscopy is proposed to detect the presence of pores in the lap joint of laser welded AZ31B magnesium alloy. The electron temperature that is calculated by the Boltzmann plot method is correlated to the presence of pores in the weld bead. A separate series of experiments was performed to evaluate the effect of an oxide coating layer on the dynamic behavior of the molten pool in the laser welding of an AZ31B magnesium alloy in a zero-gap lap joint configuration. A high speed CCD camera assisted with a green laser as an illumination source was selected to record the weld pool dynamics. Another technique used in this study was two-pass laser welding process to join AZ31B magnesium sheet in a zero-gap, lap-shear configuration. Two groups of samples including one pass laser welding (OPLW) and two pass laser welding (TPLW) were studied. In the two pass laser welding procedure, the first pass is performed by a defocused laser beam on the top of the two overlapped sheets in order to preheat the faying surface prior to laser welding, while the second pass is applied to melt and eventually weld the samples. Tensile and microhardness tests were used to measure the mechanical properties of the laser welded samples. A spectrometer was also used in real-time to correlate pore formation with calculated electron temperature using the Boltzmann plot method. The results of calculated electron temperature confirmed the previous results in earlier chapter. Magnesium and aluminum are two alloys which are used in different industries mainly due to their light weight. The main use of these two alloys is in automotive industry. Since different parts of the automobiles can be manufactured with each of these two alloys, it is essential to evaluate the joining feasibility of dissimilar metals such as aluminum to magnesium. A 4 kW fiber laser is used to join AZ31B magnesium alloy to AA 6014 using an overlap joint configuration. Two

  19. Strategies for active alignment of lenses

    NASA Astrophysics Data System (ADS)

    Langehanenberg, Patrik; Heinisch, Josef; Wilde, Chrisitan; Hahne, Felix; Lüerß, Bernd

    2015-10-01

    Today's optical systems require up-to-date assembly and joining technology. The trend of keeping dimensions as small as possible while maintaining or increasing optical imaging performance leaves little to no room for mechanical lens adjustment equipment that may remain in the final product. In this context active alignment of optical elements opens up possibilities for the fast and cost-economic manufacturing of lenses and lens assemblies with highest optical performance. Active alignment for lens manufacturing is the precise alignment of the optical axis of a lens with respect to an optical or mechanical reference axis (e.g. housing) including subsequent fixation by glue. In this contribution we will describe different approaches for active alignment and outline strengths and limitations of the different methods. Using the SmartAlign principle, highest quality cemented lenses can be manufactured without the need for high precision prealignment, while the reduction to a single alignment step greatly reduces the cycle time. The same strategies can also be applied to bonding processes. Lenses and lens groups can be aligned to both mechanical and optical axes to maximize the optical performance of a given assembly. In hybrid assemblies using both mechanical tolerances and active alignment, SmartAlign can be used to align critical lens elements anywhere inside the system for optimized total performance. Since all geometrical parameters are re-measured before each alignment, this process is especially suited for complex and time-consuming production processes where the stability of the reference axis would otherwise be critical. For highest performance, lenses can be actively aligned using up to five degrees of freedom. In this way, SmartAlign enables the production of ultra-precise mounted lenses with an alignment precision below 1 μm.

  20. A Transmittance-optimized, Point-focus Fresnel Lens Solar Concentrator

    NASA Technical Reports Server (NTRS)

    Oneill, M. J.

    1984-01-01

    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.

  1. Novel copyright information hiding method based on random phase matrix of Fresnel diffraction transforms

    NASA Astrophysics Data System (ADS)

    Cao, Chao; Chen, Ru-jun

    2009-10-01

    In this paper, we present a new copyright information hide method for digital images in Moiré fringe formats. The copyright information is embedded into the protected image and the detecting image based on Fresnel phase matrix. Firstly, using Fresnel diffraction transform, the random phase matrix of copyright information is generated. Then, according to Moiré fringe principle, the protected image and the detecting image are modulated respectively based on the random phase matrix, and the copyright information is embedded into them. When the protected image and the detecting image are overlapped, the copyright information can reappear. Experiment results show that our method has good concealment performance, and is a new way for copyright protection.

  2. Image magnification in lensless holographic projection using double-sampling Fresnel diffraction.

    PubMed

    Qu, Weidong; Gu, Huarong; Zhang, Hao; Tan, Qiaofeng

    2015-12-01

    Since the diffraction angle is limited by the spatial resolution of the spatial light modulator (SLM), the size of the optical image of the lensless holographic projection with a SLM is very small. Using a divergent spherical beam to illuminate a SLM is an effective method to physically increase the projection angle; nevertheless, the sampling ranges of the existing Fresnel diffraction algorithms with fast Fourier transform keep unchanged. In this paper, a double-sampling Fresnel diffraction algorithm to enlarge the sampling range is proposed when using a divergent spherical beam to illuminate a SLM, and the magnification of the optical image is realized in lensless holographic projection. The hologram can be easily optimized by the Gerschberg-Saxton algorithm. Simulation and experimental results with enlarged optical image are presented successfully. PMID:26836654

  3. Single-exposure multiphoton fabrication of polygonized structures by an SLM-modulated Fresnel zone lens

    NASA Astrophysics Data System (ADS)

    Zhang, Chenchu; Hu, Yanlei; Li, Jiawen; Lao, Zhaoxin; Xu, Bing; Ni, Jincheng; Cai, Ze; Wu, Dong; Chu, Jiaru

    2016-03-01

    Recently, annular beams have been developed to rapidly fabricate microscope tubular structures via two-photon polymerization, but the distribution of the light field is limited to a ring pattern. Here a Fresnel lens is designed and applied to modulate the light field into a uniform quadrangle or hexagon shape with controllable diameters. By applying a spatial light modulator to load the phase information of the Fresnel lens, quadrangle and hexagon structures are achieved through single exposure of a femtosecond laser. A 3×6 array of structures is made within 9 s. Comparing with the conventional holographic processing, this method shows higher uniformity, high efficiency, better flexibility, and easy operation. The approach exhibited a promising prospect in rapidly fabricating structures such as tissue engineering scaffolds and variously shaped tubular arrays.

  4. Visual effect of a linear Fresnel lens illuminated with a directional backlight.

    PubMed

    Li, Kunyang; Fan, Hang; Wang, Jiahui; Xu, Yuman; Zhou, Jianying; Zhou, Yangui

    2016-06-01

    A linear Fresnel lens illuminated by a directional backlight is studied. The light distribution on the lens surface visualized by a retina is simulated with a Monte Carlo ray-tracing technique, and the visualized display uniformity on the lens surface is found to depend critically on the lens quality as well as on the viewing position away from the light propagation axis. The effect of the light source configuration as well as the deviation of the microstructures of the Fresnel lens from ideal structure are studied. The simulation is verified with an experimental study, and good agreement between numerical and experimental results is obtained. Design guidelines are presented for a backlight-illuminated system to achieve high-quality uniform flat-panel two-dimensional and autostereoscopic displays. PMID:27409444

  5. The calculation of electromagnetic fields in the Fresnel and Fraunhofer regions using numerical integration methods

    NASA Technical Reports Server (NTRS)

    Schmidt, R. F.

    1971-01-01

    Some results obtained with a digital computer program written at Goddard Space Flight Center to obtain electromagnetic fields scattered by perfectly reflecting surfaces are presented. For purposes of illustration a paraboloidal reflector was illuminated at radio frequencies in the simulation for both receiving and transmitting modes of operation. Fields were computed in the Fresnel and Fraunhofer regions. A dual-reflector system (Cassegrain) was also simulated for the transmitting case, and fields were computed in the Fraunhofer region. Appended results include derivations which show that the vector Kirchhoff-Kottler formulation has an equivalent form requiring only incident magnetic fields as a driving function. Satisfaction of the radiation conditions at infinity by the equivalent form is demonstrated by a conversion from Cartesian to spherical vector operators. A subsequent development presents the formulation by which Fresnel or Fraunhofer patterns are obtainable for dual-reflector systems. A discussion of the time-average Poynting vector is also appended.

  6. Weak gravitational lensing with the Square Kilometre Array

    NASA Astrophysics Data System (ADS)

    Brown, M.; Bacon, D.; Camera, S.; Harrison, I.; Joachimi, B.; Metcalf, R. B.; Pourtsidou, A.; Takahashi, K.; Zuntz, J.; Abdalla, F. B.; Bridle, S.; Jarvis, M.; Kitching, T.; Miller, L.; Patel, P.

    2015-04-01

    We investigate the capabilities of various stages of the SKA to perform world-leading weak gravitational lensing surveys. We outline a way forward to develop the tools needed for pursuing weak lensing in the radio band. We identify the key analysis challenges and the key pathfinder experiments that will allow us to address them in the run up to the SKA. We identify and summarize the unique and potentially very powerful aspects of radio weak lensing surveys, facilitated by the SKA, that can solve major challenges in the field of weak lensing. These include the use of polarization and rotational velocity information to control intrinsic alignments, and the new area of weak lensing using intensity mapping experiments. We show how the SKA lensing surveys will both complement and enhance corresponding efforts in the optical wavebands through cross-correlation techniques and by way of extending the reach of weak lensing to high redshift.

  7. Fabrication of a multilevel THz Fresnel lens by femtosecond laser ablation

    NASA Astrophysics Data System (ADS)

    Komlenok, M. S.; Volodkin, B. O.; Knyazev, B. A.; Kononenko, T. V.; Kononenko, V. V.; Konov, V. I.; Soifer, V. A.; Pavel'ev, V. S.; Tukmakov, K. N.; Choporova, Yu Yu

    2015-10-01

    The possibility of fabricating a silicon diffractive fourlevel THz Fresnel lens by laser ablation is studied. For a microrelief to be formed on the sample surface, use is made of a femtosecond Yb : YAG laser with a high pulse repetition rate (f = 200 kHz). Characteristics of the diffractive optical element are investigated in the beam of a 141-mm free-electron laser. The measured diffraction efficiency of the lens is in good agreement with the theoretical estimate.

  8. Everything you wanted to know about Fresnel diffraction (but were afraid to ask)

    NASA Astrophysics Data System (ADS)

    Dickinson, Dale F.

    A simple method is presented for estimating the diffraction effects due to a rectangular screen. A dimensionless index involving wavelength, screen size and screen-background distance is used in conjunction with a graph to obtain an estimate of the intensity in the shadow region. With careful use, the method should yield an answer within 10 percent of the correct value. The amplitude and intensity solutions for Fresnel diffraction by a rectangular obstacle are also presented.

  9. Light propagation in local and linear media: Fresnel-Kummer wave surfaces with 16 singular points

    NASA Astrophysics Data System (ADS)

    Favaro, Alberto; Hehl, Friedrich W.

    2016-01-01

    It is known that the Fresnel wave surfaces of transparent biaxial media have four singular points, located on two special directions. We show that, in more general media, the number of singularities can exceed 4. In fact, a highly symmetric linear material is proposed whose Fresnel surface exhibits 16 singular points. Because for every linear material the dispersion equation is quartic, we conclude that 16 is the maximum number of isolated singularities. The identity of Fresnel and Kummer surfaces, which holds true for media with a certain symmetry (zero skewon piece), provides an elegant interpretation of the results. We describe a metamaterial realization for our linear medium with 16 singular points. It is found that an appropriate combination of metal bars, split-ring resonators, and magnetized particles can generate the correct permittivity, permeability, and magnetoelectric moduli. Lastly, we discuss the arrangement of the singularities in terms of Kummer's 166 configuration of points and planes. An investigation parallel to ours, but in linear elasticity, is suggested for future research.

  10. Polarization effects in active Fresnel rhomb zig-zag slab amplifier

    SciTech Connect

    Bikmatov, R.G.; Chernyak, V.M.; Ignat`ev, L.P.; Kuznetsov, V.G.; Pergament, M.I.; Smirnov, R.V.; Sokolov, V.I.; Hunt, J.T.; Manes, K.

    1997-01-27

    The concept to use a slab as active element, working in zig-zag geometry, and also as Fresnel rhomb, seems to be rather attractive. However, in this case different depolarization effects in active element arc of crucial importance. We have carried out the estimations of depolarization effects arising both due to mechanical loading of an active element at its fastening and due to thermooptical distortions. To check up these rigid requirements to depolarization (0.1 % - 0.01 %) careful measurements of depolarization effects and their sources are being carried out. Mechanical loading gives one of the main contributions in depolarization at fastening of active element. Using model experiments with glass Fresnel rhomb under mechanical loading we have measured depolarization effects. It is proposed to use additional glass plate to compensate beam depolarization in zig-zag slab. The received results allow to expect successful use of the slab amplifier as a Fresnel rhomb providing rather high quality of optical material of active clement.

  11. Solar Sail - Fresnel Zone Plate Lens for a Large Space Based Telescope

    SciTech Connect

    Early, J T

    2002-02-13

    A Fresnel zone plate lens made with solar sail material could be used as the primary optic for a very large aperture telescope on deep space probes propelled by solar sails. The large aperture telescope capability could enable significant science on fly-by missions to the asteroids, Pluto, Kuiper belt or the tort cloud and could also enable meaningful interstellar fly-by missions for laser propelled sails. This type of lens may also have some potential for laser communications and as a solar concentrator. The techniques for fabrication of meter size and larger Fresnel phase plate optics are under development at LLNL, and we are extending this technology to amplitude zone plates made from sail materials. Corrector optics to greatly extend the bandwidth of these Fresnel optics will be demonstrated in the future. This novel telescope concept will require new understanding of the fabrication, deployment and control of gossamer space structures. It will also require new materials technology for fabricating these optics and understanding their long term stability in a space environment.

  12. Computer-based classification of bacteria species by analysis of their colonies Fresnel diffraction patterns

    NASA Astrophysics Data System (ADS)

    Suchwalko, Agnieszka; Buzalewicz, Igor; Podbielska, Halina

    2012-01-01

    In the presented paper the optical system with converging spherical wave illumination for classification of bacteria species, is proposed. It allows for compression of the observation space, observation of Fresnel patterns, diffraction pattern scaling and low level of optical aberrations, which are not possessed by other optical configurations. Obtained experimental results have shown that colonies of specific bacteria species generate unique diffraction signatures. Analysis of Fresnel diffraction patterns of bacteria colonies can be fast and reliable method for classification and recognition of bacteria species. To determine the unique features of bacteria colonies diffraction patterns the image processing analysis was proposed. Classification can be performed by analyzing the spatial structure of diffraction patterns, which can be characterized by set of concentric rings. The characteristics of such rings depends on the bacteria species. In the paper, the influence of basic features and ring partitioning number on the bacteria classification, is analyzed. It is demonstrated that Fresnel patterns can be used for classification of following species: Salmonella enteritidis, Staplyococcus aureus, Proteus mirabilis and Citrobacter freundii. Image processing is performed by free ImageJ software, for which a special macro with human interaction, was written. LDA classification, CV method, ANOVA and PCA visualizations preceded by image data extraction were conducted using the free software R.

  13. International shipment of light weight radioisotopic heater units (LWRHU) using the USA/9516/B(U)F Mound 1 kW shipping package in support of the 'Pluto Express' mission

    SciTech Connect

    Barklay, Chadwick D.; Merten, C. William

    1997-01-10

    Radioisotopes have provided heat that has been used to maintain specific operating environments within remote satellites and spacecraft. For the 'Pluto Express' mission the {sup 238}PuO{sub 2} fueled light weight radioisotopic heater unit (LWRHU) will be used within the spacecraft. Since the current plan for the 'Pluto Express' mission incorporates the use of a Russian launch platform for the spacecraft, the LWRHUs must be transported in an internationally certified shipping container. An internationally certified shipping package that is versatile enough to be reconfigured to transport the LWRHUs that will be required to support the 'Pluto Express' mission is the Mound USA/9516/B(U)F.

  14. Baryons, neutrinos, feedback and weak gravitational lensing

    NASA Astrophysics Data System (ADS)

    Harnois-Déraps, Joachim; van Waerbeke, Ludovic; Viola, Massimo; Heymans, Catherine

    2015-06-01

    The effect of baryonic feedback on the dark matter mass distribution is generally considered to be a nuisance to weak gravitational lensing. Measurements of cosmological parameters are affected as feedback alters the cosmic shear signal on angular scales smaller than a few arcminutes. Recent progress on the numerical modelling of baryon physics has shown that this effect could be so large that, rather than being a nuisance, the effect can be constrained with current weak lensing surveys, hence providing an alternative astrophysical insight on one of the most challenging questions of galaxy formation. In order to perform our analysis, we construct an analytic fitting formula that describes the effect of the baryons on the mass power spectrum. This fitting formula is based on three scenarios of the OverWhelmingly Large hydrodynamical simulations. It is specifically calibrated for z < 1.5, where it models the simulations to an accuracy that is better than 2 per cent for scales k < 10 h Mpc-1 and better than 5 per cent for 10 < k < 100 h Mpc-1. Equipped with this precise tool, this paper presents the first constraint on baryonic feedback models using gravitational lensing data, from the Canada France Hawaii Telescope Lensing Survey (CFHTLenS). In this analysis, we show that the effect of neutrino mass on the mass power spectrum is degenerate with the baryonic feedback at small angular scales and cannot be ignored. Assuming a cosmology precision fixed by WMAP9, we find that a universe with massless neutrinos is rejected by the CFHTLenS lensing data with 85-98 per cent confidence, depending on the baryon feedback model. Some combinations of feedback and non-zero neutrino masses are also disfavoured by the data, although it is not yet possible to isolate a unique neutrino mass and feedback model. Our study shows that ongoing weak gravitational lensing surveys (KiDS, HSC and DES) will offer a unique opportunity to probe the physics of baryons at galactic scales, in

  15. Weak Gravitatational Lensing by Illustris-1 Galaxies

    NASA Astrophysics Data System (ADS)

    Brainerd, Tereasa G.; Koh, Patrick H.

    2016-06-01

    We compute the weak gravitational lensing signal of isolated, central galaxies obtained from the z=0.5 timestep of the ΛCDM Illustris-1 simulation. The galaxies have stellar masses ranging from 9.5 ≤ log10(M*/Msun) ≤ 11.0 and are located outside cluster and rich group environments. Although there is local substructure present in the form of small, luminous satellite galaxies, the central galaxies are the dominant objects within the virial radii (r200), and each central galaxy is at least 5 times brighter than any other luminous galaxy within the friends-of-friends halo. We compute the weak lensing signal within projected radii 0.05 < rp/r200 < 1.5 and investigate the degree to which the weak lensing signal is anisotropic. Since CDM halos are non-spherical, the weak lensing signal is expected to be anisotropic; however, the degree of anisotropy that is observed depends upon the symmetry axes that are used to define the geometry. The anisotropy is expected to be maximized when the major axis of the projected dark matter mass distribution is used to define the geomety. In practice in the observed universe, one must necessarily use the projected distribution of the luminous mass to define the geometry. If mass and light are not well-aligned, this results in a suppression of the weak lensing anistropy. Our initial analysis shows that the ellipticity of the projected dark matter halo is uncorrelated with the ellipticity of the projected stellar mass. That is εhalo ≠ f × εlight, where f is a constant multiplicative factor. In addition, in projection on the sky, the major axis of the dark matter mass is offset from that of the stellar mass by ∼40o on average. On scales rp ≤ 0.15 r200, the weak lensing anisotropy obtained when using the stellar mass to define the geometry is of order 7% and agrees well with the anisotropy obtained when using the dark matter mass to define the geometry. On scales rp ∼ r200, the anisotropy obtained when using the stellar mass

  16. Consideration of the first Fresnel zone characterisation while investigating on seismoelectric interfacial conversions

    NASA Astrophysics Data System (ADS)

    Holzhauer, J.; Günther, T.; Yaramanci, U.

    2012-04-01

    Over the past years, seismoelectric field measurements have been developed at a previously investigated test-site. Recent improvements in our seismic triggering system enabled the systematic gathering of seismoelectric records, using various seismic sources, ranging from hammer to vibrator over weight-drops. Those field data apparently displayed both the coseismic and the interfacial converted EM-waves. To first assess and then analyse dipole attributes of the latter, we compared three different approaches for calculating the electrical record along a surface profile induced by a vertical electric dipole at depth. The first basic approach consisted in a unique and constant vertical electric dipole placed at the center of the first Fresnel zone. The second approach relies on the discretisation of this first Fresnel zone and the summation of a multitude of constant vertical electric dipoles. The last approach involves a multitude of oscillating dipoles in addition to a discretised Fresnel zone. In all three approaches the free parameters, used to compute the vertical electric dipole, are the depth of the interface h and the adjusting amplitude parameter A, expressed in Volt. Amplitude A accounts for both the characteristics of the source and the interface (contrast of electric and hydraulic parameters). Preliminary results show that the accuracy of the unique dipole approximation is limited: field observations are better accounted for using discretised Fresnel zone. The oscillating dipoles approach offers a slightly better correlation to field data but requires a much higher computation time. Hence the second approach, involving a discretised Fresnel zone with a multitude of constant vertical electric dipoles, seems most appropriate. RMS-analysis of amplitude distribution for identified interfacial converted EM-signals were conducted in order to determine the best fitting parameters (h, A). Field data acquired with various seismic sources, appeared to display similar

  17. Design and fabrication of the progressive addition lenses

    NASA Astrophysics Data System (ADS)

    Qin, Linling; Qian, Lin; Yu, Jingchi

    2011-11-01

    The use of progressive addition lenses (PALs) for the correction of presbyopia has increased dramatically in recent years. These lenses are now being used as the preferred alternative to bifocal and trifocal lenses in many parts of the world. Progressive addition lenses are a kind of opthalmic lenses with freeform surface. The surface curvature of the Progressive addition lenses varies gradually from a minimum value in the upper area, to a maximum value in the lower area. Thus a PAL has a surface with three zones which have very small astigmatism: far-view zone, near-view zone, and intermediate zone. The far view zone and near view zone have relatively constant powers and connected by the intermediate zone with power varies progressively. The design and fabrication technologies of progressive addition lenses have fast progresses because of the massive development of the optical simulation software, multi-axis ultraprecision machining technologies and CNC machining technologies. The design principles of progressive addition lenses are discussed in a historic review. Several kinds of design methods are illustrated, and their advantages and disadvantages are also represented. In the current study, it is shown that the optical characteristics of the different progressive addition lenses designs are significantly different from one another. The different fabrication technologies of Progressive addition lenses are also discussed in the paper. Plastic injection molding and precision-machine turning are the common fabrication technologies for exterior PALs and Interior PALs respectively.

  18. Tunable lenses using transparent dielectric elastomer actuators.

    PubMed

    Shian, Samuel; Diebold, Roger M; Clarke, David R

    2013-04-01

    Focus tunable, adaptive lenses provide several advantages over traditional lens assemblies in terms of compactness, cost, efficiency, and flexibility. To further improve the simplicity and compact nature of adaptive lenses, we present an elastomer-liquid lens system which makes use of an inline, transparent electroactive polymer actuator. The lens requires only a minimal number of components: a frame, a passive membrane, a dielectric elastomer actuator membrane, and a clear liquid. The focal length variation was recorded to be greater than 100% with this system, responding in less than one second. Through the analysis of membrane deformation within geometrical constraints, it is shown that by selecting appropriate lens dimensions, even larger focusing dynamic ranges can be achieved. PMID:23571956

  19. Interferometric Plasmonic Lensing with Nanohole Arrays

    SciTech Connect

    Gong, Yu; Joly, Alan G.; El-Khoury, Patrick Z.; Hess, Wayne P.

    2014-12-18

    Nonlinear photoemission electron microscopy (PEEM) of nanohole arrays in gold films maps propagating surface plasmons (PSPs) launched from lithographically patterned structures. Strong near field photoemission patterns are observed in the PEEM images, recorded following low angle of incidence irradiation of nanohole arrays with sub-15 fs laser pulses centered at 780 nm. The recorded photoemission patterns are attributed to constructive and destructive interferences between PSPs launched from the individual nanoholes which comprise the array. By exploiting the wave nature of PSPs, we demonstrate how varying the array geometry (hole diameter, pitch, and number of rows/columns) ultimately yields intense localized photoemission. Through a combination of PEEM and finite-difference time-domain simulations, we identify the optimal array geometry for efficient light coupling and interferometric plasmonic lensing. We show a preliminary application of inteferometric plasmonic lensing by enhancing the photoemission from the vertex of a gold triangle using nanohole array.

  20. Antifouling leaching technique for optical lenses

    USGS Publications Warehouse

    Strahle, William J.; Perez, C. L.; Martini, Marinna A.

    1994-01-01

    The effectiveness of optical lenses deployed in water less than 100 m deep is significantly reduced by biofouling caused by the settlement of macrofauna, such as barnacles, hydroids, and tunicates. However, machineable porous plastic rings can be used to dispense antifoulant into the water in front of the lens to retard macrofaunal growth without obstructing the light path. Unlike coatings which can degrade the optical performance, antifouling rings do not interfere with the instrument optics. The authors have designed plastic, reusable cup-like antifouling rings to slip over the optical lenses of a transmissometer. These rings have been used for several deployments on shallow moorings in Massachusetts Bay, MA and have increased the time before fouling degrades optical characteristics

  1. Astrophysical observations: lensing and eclipsing Einstein's theories.

    PubMed

    Bennett, Charles L

    2005-02-11

    Albert Einstein postulated the equivalence of energy and mass, developed the theory of special relativity, explained the photoelectric effect, and described Brownian motion in five papers, all published in 1905, 100 years ago. With these papers, Einstein provided the framework for understanding modern astrophysical phenomena. Conversely, astrophysical observations provide one of the most effective means for testing Einstein's theories. Here, I review astrophysical advances precipitated by Einstein's insights, including gravitational redshifts, gravitational lensing, gravitational waves, the Lense-Thirring effect, and modern cosmology. A complete understanding of cosmology, from the earliest moments to the ultimate fate of the universe, will require developments in physics beyond Einstein, to a unified theory of gravity and quantum physics. PMID:15705841

  2. The geometry of gravitational lensing magnification

    NASA Astrophysics Data System (ADS)

    Aazami, Amir Babak; Werner, Marcus C.

    2016-02-01

    We present a definition of unsigned magnification in gravitational lensing valid on arbitrary convex normal neighborhoods of time oriented Lorentzian manifolds. This definition is a function defined at any two points along a null geodesic that lie in a convex normal neighborhood, and foregoes the usual notions of lens and source planes in gravitational lensing. Rather, it makes essential use of the van Vleck determinant, which we present via the exponential map, and Etherington's definition of luminosity distance for arbitrary spacetimes. We then specialize our definition to spacetimes, like Schwarzschild's, in which the lens is compact and isolated, and show that our magnification function is monotonically increasing along any geodesic contained within a convex normal neighborhood.

  3. Contamination of early-type galaxy alignments to galaxy lensing-CMB lensing cross-correlation

    NASA Astrophysics Data System (ADS)

    Chisari, Nora Elisa; Dunkley, Joanna; Miller, Lance; Allison, Rupert

    2015-10-01

    Galaxy shapes are subject to distortions due to the tidal field of the Universe. The cross-correlation of galaxy lensing with the lensing of the cosmic microwave background (CMB) cannot easily be separated from the cross-correlation of galaxy intrinsic shapes with CMB lensing. Previous work suggested that the intrinsic alignment contamination can be 15 per cent of this cross-spectrum for the CFHT Stripe 82 (CS82) and Atacama Cosmology Telescope surveys. Here we re-examine these estimates using up-to-date observational constraints of intrinsic alignments at a redshift more similar to that of CS82 galaxies. We find an ≈10 per cent contamination of the cross-spectrum from red galaxies, with ≈3 per cent uncertainty due to uncertainties in the redshift distribution of source galaxies and the modelling of the spectral energy distribution. Blue galaxies are consistent with being unaligned, but could contaminate the cross-spectrum by an additional 9.5 per cent within current 95 per cent confidence levels. While our fiducial estimate of alignment contamination is similar to previous work, our work suggests that the relevance of alignments for CMB lensing-galaxy lensing cross-correlation remains largely unconstrained. Little information is currently available about alignments at z > 1.2. We consider the upper limiting case where all z > 1.2 galaxies are aligned with the same strength as low-redshift luminous red galaxies, finding as much as ≈60 per cent contamination.

  4. Zoom lenses for infra-red applications

    NASA Astrophysics Data System (ADS)

    Debize, Jacques; Nory, Pierre

    1986-01-01

    IR zoom lenses, which are used by such optoelectronic systems as thermal imagers and lasers, require precise optimization of lens design, high precision aspheric surfaces, high efficiency antireflection coatings, and sufficiently high mechanical precision to achieve the necessary boresight shift. Precision requirements are made the more critical by the use of optical materials permitting small surface dimensions, such as Ge, ZnSe, and ZnS.

  5. Fitting gravitational lenses: truth or delusion

    NASA Astrophysics Data System (ADS)

    Evans, N. Wyn; Witt, Hans J.

    2003-11-01

    The observables in a strong gravitational lens are usually just the image positions and sometimes the flux ratios. We develop a new and simple algorithm which allows a set of models to be fitted exactly to the observations. Taking our cue from the strong body of evidence that early-type galaxies are close to isothermal, we assume that the lens is scale-free with a flat rotation curve. External shear can be easily included. Our algorithm allows full flexibility regarding the angular structure of the lensing potential. Importantly, all the free parameters enter linearly into the model and so the lens and flux ratio equations can always be solved by straightforward matrix inversion. The models are only restricted by the fact that the surface mass density must be positive. We use this new algorithm to examine some of the claims made for anomalous flux ratios. It has been argued that such anomalies betray the presence of substantial amounts of substructure in the lensing galaxy. We demonstrate by explicit construction that some of the lens systems for which substructure has been claimed can be well fitted by smooth lens models. This is especially the case when the systematic errors in the flux ratios (caused by microlensing or differential extinction) are taken into account. However, there is certainly one system (B1422+231) for which the existing smooth models are definitely inadequate and for which substructure may be implicated. Within a few tens of kpc of the lensing galaxy centre, dynamical friction and tidal disruption are known to be very efficient at dissolving any substructure. Very little substructure is projected within the Einstein radius. The numbers of strong lenses for which substructure is currently being claimed may be so large that this contradicts rather than supports cold dark matter theories.

  6. Antireflection coatings for submillimeter silicon lenses

    NASA Astrophysics Data System (ADS)

    Wheeler, Jordan D.; Koopman, Brian; Gallardo, Patricio; Maloney, Philip R.; Brugger, Spencer; Cortes-Medellin, German; Datta, Rahul; Dowell, C. Darren; Glenn, Jason; Golwala, Sunil; McKenney, Chris; McMahon, Jeffery J.; Munson, Charles D.; Niemack, Mike; Parshley, Stephen; Stacey, Gordon

    2014-07-01

    Low-loss lenses are required for submillimeter astronomical applications, such as instrumentation for CCAT, a 25 m diameter telescope to be built at an elevation of 18,400 ft in Chile. Silicon is a leading candidate for dielectric lenses due to its low transmission loss and high index of refraction; however, the latter can lead to large reflection losses. Additionally, large diameter lenses (up to 40 cm), with substantial curvature present a challenge for fabrication of antireflection coatings. Three anti-reflection coatings are considered: a deposited dielectric coating of Parylene C, fine mesh structures cut with a dicing saw, and thin etched silicon layers (fabricated with deep reactive ion etching) for bonding to lenses. Modeling, laboratory measurements, and practicalities of fabrication for the three coatings are presented and compared. Measurements of the Parylene C anti-reflection coating were found to be consistent with previous studies and can be expected to result in a 6% transmission loss for each interface from 0.787 to 0.908 THz. The thin etched silicon layers and fine mesh structure anti-reflection coatings were designed and fabricated on test silicon wafers and found to have reflection losses less than 1% at each interface from 0.787 to 0.908 THz. The thin etched silicon layers are our preferred method because of high transmission efficiency while having an intrinsically faster fabrication time than fine structures cut with dicing saws, though much work remains to adapt the etched approach to curved surfaces and optics < 4" in diameter unlike the diced coatings.

  7. SimpLens: Interactive gravitational lensing simulator

    NASA Astrophysics Data System (ADS)

    Saha, Prasenjit; Williams, Liliya L. R.

    2016-06-01

    SimpLens illustrates some of the theoretical ideas important in gravitational lensing in an interactive way. After setting parameters for elliptical mass distribution and external mass, SimpLens displays the mass profile and source position, the lens potential and image locations, and indicate the image magnifications and contours of virtual light-travel time. A lens profile can be made shallower or steeper with little change in the image positions and with only total magnification affected.

  8. Digital holographic testing of biconvex lenses.

    PubMed

    Chhaniwal, V K; Kihiko, J M; Dubey, S; Shearon, G; Javidi, B; Anand, A

    2013-12-20

    Lenses are one of the most important optical elements for manipulation of wavefronts. For their proper selection, the wavefronts produced by the lenses should be analyzed. Digital holography is a tool which provides whole-field reconstructions of wavefronts, and here the use of digital holographic interferometry in complete characterization of wavefronts from lenses is investigated. Digital holograms of the wavefront from the test lens are recorded for various positions of the test lens from a point source. The reconstructed phase of the wavefront from the test lens is compared with a digitally inputted wavefront for measurement of parallelism as well as curvature. The focal length of the test lens is computed by measuring the change in curvature of the wavefront for two positions of the test lens. The radius of curvature of the test lens is determined by using the test lens in the reflection mode. Refractive index of the lens material is also determined using this method. Detailed theoretical and experimental analysis is provided. PMID:24513936

  9. Micromachined silicon lenses for terahertz applications

    NASA Astrophysics Data System (ADS)

    Bueno, J.; López-Camacho, E.; Silva-López, M.; Rico-García, J. M.; Llombart, N.; Alda, J.; Costa-Krämer, J. L.

    2013-11-01

    Silicon microlenses are a very important tool for coupling terahertz (THz) radiation into antennas and detectors in integrated circuits. They can be used in a large array structures at this frequency range reducing considerably the crosstalk between the pixels. Drops of photoresist have been deposited and their shape transferred into the silicon by means of a Reactive Ion Etching (RIE) process. Large silicon lenses with a few mm diameter (between 1.5 and 4.5 mm) and hundreds of μm height (between 50 and 350 μm) have been fabricated. The surface of such lenses has been characterized using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM), resulting in a surface roughness of about ˜3 μm, good enough for any THz application. The beam profile at the focal plane of such lenses has been measured at a wavelength of 10.6 μm using a tomographic knife-edge technique and a CO2 laser.

  10. The CASTLES Imaging Survey of Gravitational Lenses

    NASA Astrophysics Data System (ADS)

    Peng, C. Y.; Falco, E. E.; Lehar, J.; Impey, C. D.; Kochanek, C. S.; McLeod, B. A.; Rix, H.-W.

    1997-12-01

    The CASTLES survey (Cfa-Arizona-(H)ST-Lens-Survey) is imaging most known small-separation gravitational lenses (or lens candidates), using the NICMOS camera (mostly H-band) and the WFPC2 (V and I band) on HST. To date nearly half of the IR imaging survey has been completed. The main goals are: (1) to search for lens galaxies where none have been directly detected so far; (2) obtain photometric redshift estimates (VIH) for the lenses where no spectroscopic redshifts exist; (3) study and model the lens galaxies in detail, in part to study the mass distribution within them, in part to identify ``simple" systems that may permit accurate time delay estimates for H_0; (3) measure the M/L evolution of the sample of lens galaxies with look-back time (to z ~ 1); (4) determine directly which fraction of sources are lensed by ellipticals vs. spirals. We will present the survey specifications and the images obtained so far.

  11. Tevatron electron lenses: Design and operation

    NASA Astrophysics Data System (ADS)

    Shiltsev, Vladimir; Bishofberger, Kip; Kamerdzhiev, Vsevolod; Kozub, Sergei; Kufer, Matthew; Kuznetsov, Gennady; Martinez, Alexander; Olson, Marvin; Pfeffer, Howard; Saewert, Greg; Scarpine, Vic; Seryi, Andrey; Solyak, Nikolai; Sytnik, Veniamin; Tiunov, Mikhail; Tkachenko, Leonid; Wildman, David; Wolff, Daniel; Zhang, Xiao-Long

    2008-10-01

    The beam-beam effects have been the dominating sources of beam loss and lifetime limitations in the Tevatron proton-antiproton collider [V. Shiltsev , Phys. Rev. ST Accel. Beams 8, 101001 (2005)PRABFM1098-440210.1103/PhysRevSTAB.8.101001]. Electron lenses were originally proposed for compensation of electromagnetic long-range and head-on beam-beam interactions of proton and antiproton beams [V. Shiltsev , Phys. Rev. ST Accel. Beams 2, 071001 (1999).PRABFM1098-440210.1103/PhysRevSTAB.2.071001]. Results of successful employment of two electron lenses built and installed in the Tevatron are reported by Shiltsev et al. [Phys. Rev. Lett. 99, 244801 (2007)PRLTAO0031-900710.1103/PhysRevLett.99.244801; New J. Phys. 10, 043042 (2008)NJOPFM1367-263010.1088/1367-2630/10/4/043042] and by Zhang et al. [X.-L. Zhang , Phys. Rev. ST Accel. Beams 11, 051002 (2008)PRABFM1098-440210.1103/PhysRevSTAB.11.051002]. 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.

  12. Automation Enhancement of Multilayer Laue Lenses

    SciTech Connect

    Lauer K. R.; Conley R.

    2010-12-01

    X-ray optics fabrication at Brookhaven National Laboratory has been facilitated by a new, state of the art magnetron sputtering physical deposition system. With its nine magnetron sputtering cathodes and substrate carrier that moves on a linear rail via a UHV brushless linear servo motor, the system is capable of accurately depositing the many thousands of layers necessary for multilayer Laue lenses. I have engineered a versatile and automated control program from scratch for the base system and many subsystems. Its main features include a custom scripting language, a fully customizable graphical user interface, wireless and remote control, and a terminal-based interface. This control system has already been successfully used in the creation of many types of x-ray optics, including several thousand layer multilayer Laue lenses.Before reaching the point at which a deposition can be run, stencil-like masks for the sputtering cathodes must be created to ensure the proper distribution of sputtered atoms. Quality of multilayer Laue lenses can also be difficult to measure, given the size of the thin film layers. I employ my knowledge of software and algorithms to further ease these previously painstaking processes with custom programs. Additionally, I will give an overview of an x-ray optic simulator package I helped develop during the summer of 2010. In the interest of keeping my software free and open, I have worked mostly with the multiplatform Python and the PyQt application framework, utilizing C and C++ where necessary.

  13. Is There a Quad Problem Among Pptical Gravitational Lenses?

    SciTech Connect

    Oguri, Masamune

    2007-06-06

    Most of optical gravitational lenses recently discovered in the Sloan Digital Sky Survey Quasar Lens Search (SQLS) have two-images rather than four images, in marked contrast to radio lenses for which the fraction of four-image lenses (quad fraction) is quite high. We revisit the quad fraction among optical lenses by taking the selection function of the SQLS into account. We find that the current observed quad fraction in the SQLS is indeed lower than, but consistent with, the prediction of our theoretical model. The low quad fraction among optical lenses, together with the high quad fraction among radio lenses, implies that the quasar optical luminosity function has a relatively shallow faint end slope.

  14. Gravitational Lensing: Recent Progress & Future Goals

    NASA Technical Reports Server (NTRS)

    Brainerd, Tereasa

    2001-01-01

    This award was intended to provide financial support for an international astrophysics conference on gravitational lensing which was held at Boston University from July 25 to July 30, 1999. Because of the nature of the award, no specific research was proposed, nor was any carried out. The participants at the conference presented results of their on-going research efforts, and written summaries of their presentations have been published by the Astronomical Society of the Pacific as part of their conference series. The reference to the conference proceedings book is Gravitational Lensing: Recent Progress and Future Goals, ASP Conference Series volume 237, eds. T. G. Brainerd and C. S. Kochanek (2001). The ISBN number of this book is 1-58381-074-9. The goal of the conference was to bring together both senior and junior investigators who were actively involved in all aspects of gravitational lensing research. This was the first conference in four years to address gravitational lensing from such a broad perspective (the previous such conference being IAU Symposium 173 held in Melbourne, Australia in July 1995). The conference was attended by 190 participants, who represented of order 70 different institutions and of order 15 different countries. The Scientific Organizing Committee members were Matthias Bartelmann (co-chair), Tereasa Brainerd (co-chair), Ian Browne, Richard Ellis, Nick Kaiser, Yannick Mellier, Sjur Refsdal, HansWalter Rix, Joachim Wambsganss, and Rachel Webster. The Local Organizing Committee members were Tereasa Brainerd (chair), Emilio Falco, Jacqueline Hewitt, Christopher Kochanek, and Irwin Shapiro. The oral sessions were organized around specific applications of gravitational lensing and included invited reviews, invited 'targeted talks', and contributed talks. The review speakers were Roger Blandford, Tereasa Brainerd, Gus Evrard, Nick Kaiser, Guinevere Kaufmann, Chris Kochanek, Charley Lineweaver, Gerry Luppino, Shude Mao, Paul Schechter, Peter

  15. Cross-correlation of gravitational lensing from DES Science Verification data with SPT and Planck lensing

    NASA Astrophysics Data System (ADS)

    Kirk, D.; Omori, Y.; Benoit-Lévy, A.; Cawthon, R.; Chang, C.; Larsen, P.; Amara, A.; Bacon, D.; Crawford, T. M.; Dodelson, S.; Fosalba, P.; Giannantonio, T.; Holder, G.; Jain, B.; Kacprzak, T.; Lahav, O.; MacCrann, N.; Nicola, A.; Refregier, A.; Sheldon, E.; Story, K. T.; Troxel, M. A.; Vieira, J. D.; Vikram, V.; Zuntz, J.; Abbott, T. M. C.; Abdalla, F. B.; Becker, M. R.; Benson, B. A.; Bernstein, G. M.; Bernstein, R. A.; Bleem, L. E.; Bonnett, C.; Bridle, S. L.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Capozzi, D.; Carlstrom, J. E.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Crocce, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Eifler, T. F.; Evrard, A. E.; Flaugher, B.; Frieman, J.; Gerdes, D. W.; Goldstein, D. A.; Gruen, D.; Gruendl, R. A.; Honscheid, K.; James, D. J.; Jarvis, M.; Kent, S.; Kuehn, K.; Kuropatkin, N.; Lima, M.; March, M.; Martini, P.; Melchior, P.; Miller, C. J.; Miquel, R.; Nichol, R. C.; Ogando, R.; Plazas, A. A.; Reichardt, C. L.; Roodman, A.; Rozo, E.; Rykoff, E. S.; Sako, M.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Simard, G.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Wechsler, R. H.; Weller, J.

    2016-06-01

    We measure the cross-correlation between weak lensing of galaxy images and of the cosmic microwave background (CMB). The effects of gravitational lensing on different sources will be correlated if the lensing is caused by the same mass fluctuations. We use galaxy shape measurements from 139 deg2 of the Dark Energy Survey (DES) Science Verification data and overlapping CMB lensing from the South Pole Telescope (SPT) and Planck. The DES source galaxies have a median redshift of zmed ˜ 0.7, while the CMB lensing kernel is broad and peaks at z ˜ 2. The resulting cross-correlation is maximally sensitive to mass fluctuations at z ˜ 0.44. Assuming the Planck 2015 best-fitting cosmology, the amplitude of the DES×SPT cross-power is found to be ASPT = 0.88 ± 0.30 and that from DES×Planck to be APlanck = 0.86 ± 0.39, where A = 1 corresponds to the theoretical prediction. These are consistent with the expected signal and correspond to significances of 2.9σ and 2.2σ, respectively. We demonstrate that our results are robust to a number of important systematic effects including the shear measurement method, estimator choice, photo-z uncertainty and CMB lensing systematics. We calculate a value of A = 1.08 ± 0.36 for DES×SPT when we correct the observations with a simple intrinsic alignment model. With three measurements of this cross-correlation now existing in the literature, there is not yet reliable evidence for any deviation from the expected LCDM level of cross-correlation. We provide forecasts for the expected signal-to-noise ratio of the combination of the five-year DES survey and SPT-3G.

  16. Recent experience with design and manufacture of cine lenses

    NASA Astrophysics Data System (ADS)

    Thorpe, Michael D.; Dalzell, Kristen E.

    2015-09-01

    Modern cine lenses require a high degree of aberration correction over a large and ever expanding image size. At low to medium volume production levels, these highly corrected designs also require a workable tolerance set and compensation scheme for successful manufacture. In this paper we discuss the design and manufacture of cine lenses with reference to current designs both internal and in the patent literature and some experience in design, tolerancing and manufacturing these lenses in medium volume production.

  17. Ball Lenses Collimate And Focus Diode-Laser-Array Beams

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid

    1992-01-01

    Ball lenses used to collimate and focus pump light from array of diode lasers onto input face of solid-state laser. Experiments show ball lenses perform as well as, or better than, multiple-element lenses supplied heretofore as parts of commercial arrays of diode lasers. Offers advantages of relative simplicity and ease of fabrication, lower cost, lower weight, and less sensitivity to misalignment.

  18. Infrared zoom lenses in the 1980s and beyond

    NASA Astrophysics Data System (ADS)

    Mann, Allen

    1992-05-01

    Developments in the zoom lens design during the decade of 1980s are briefly reviewed. The discussion covers optically and mechanically compensated zoom lenses, refractive and reflective systems, designs with all spherical surfaces, and the use of aspherics. Also mentioned are zoom lenses in the near infrared and in the 3-5-micron wavelength region. Future developments are outlined, including binary optics and gradient index lenses.

  19. On possible use of electron lenses in LHC

    SciTech Connect

    Shiltsev, V.; /Fermilab

    2006-10-01

    We present basic facts about electron lenses used in high-energy accelerators and discuss their possible application in the LHC. Four proposals are presented: (a) electron lenses for compensation of head-on beam-beam effects; (b) electron lens as tune-spreader for better beam stability; (c) as electromagnetic primary collimator for ions and protons; (d) satellite bunch cleaning by electron lenses. Main requirements are discussed.

  20. A concentric telescopic meniscus for testing underwater lenses.

    PubMed

    Mandler, W

    1970-03-01

    In addition to being inconvenient, testing underwater lenses in their normal environment involves the difficulty of differentiating between the effects caused by the photographic system and those caused by the turbidity of the water. The principles developed and practical devices illustrated show that it is possible to apply all test methods for common photographic lenses to underwater lenses with a correctly designed concentric telescopic meniscus. PMID:20076276