Sample records for focal length optics

  1. Sighting optics including an optical element having a first focal length and a second focal length

    DOEpatents

    Crandall, David Lynn (Idaho Falls, ID)

    2011-08-01

    One embodiment of sighting optics according to the teachings provided herein may include a front sight and a rear sight positioned in spaced-apart relation. The rear sight includes an optical element having a first focal length and a second focal length. The first focal length is selected so that it is about equal to a distance separating the optical element and the front sight and the second focal length is selected so that it is about equal to a target distance. The optical element thus brings into simultaneous focus, for a user, images of the front sight and the target.

  2. Sighting optics including an optical element having a first focal length and a second focal length and methods for sighting

    DOEpatents

    Crandall, David Lynn

    2011-08-16

    Sighting optics include a front sight and a rear sight positioned in a spaced-apart relation. The rear sight includes an optical element having a first focal length and a second focal length. The first focal length is selected so that it is about equal to a distance separating the optical element and the front sight and the second focal length is selected so that it is about equal to a target distance. The optical element thus brings into simultaneous focus for a user images of the front sight and the target.

  3. Design of a variable-focal-length optical system

    NASA Technical Reports Server (NTRS)

    Ricks, D.; Shannon, R. R.

    1984-01-01

    Requirements to place an entire optical system with a variable focal length ranging from 20 to 200 cm within a overall length somewhat less than 100 cm placed severe restrictions on the design of a zoom lens suitable for use on a comet explorer. The requirements of a wavelength range of 0.4 to 1.0 microns produced even greater limitations on the possibilities for a design that included a catadioptric (using mirrors and glass) front and followed by a zooming refractive portion. Capabilities available commercial zoom lenses as well as patents of optical systems are reviewed. Preliminary designs of the refractive optics zoom lens and the catadioptric system are presented and evaluated. Of the two, the latter probably has the best chance of success, so long as the shortest focal lengths are not really needed.

  4. Measurement of MODIS optics effective focal length, distortion, and modulation transfer function

    NASA Astrophysics Data System (ADS)

    Thurlow, Paul E.; Cline, Richard W.

    1993-08-01

    A combination MODIS optics characteristics, short back focal length, and relatively distorting optics, has required major revisions in techniques used earlier to characterize effective focal length (EFL) and modulation transfer function (MTF) in the thematic mapper (TM) project. This paper compares measurement approaches used to characterize TM optics and revised methodology intended to characterize MODIS optics at an integration and assembly level.

  5. Variable focal length microlenses

    NASA Astrophysics Data System (ADS)

    L. G., Commander; Day, S. E.; Selviah, D. R.

    2000-04-01

    Refractive surface relief microlenses (150 ?m diameter) are immersed in nematic liquid crystal in a cell. Application of a variable voltage across the cell effectively varies the refractive index of the liquid crystal and results in a change of the focal length by the lensmakers formula (E. Hecht, Optics, 2nd edn., Addison-Wesley, Reading, Massachusetts, 1987, p. 138). We describe the cell design and construction and demonstrate a range of focal lengths from +490 to +1000 ?m for 2 to 12 V applied. A diverging lens results when the voltage is lower. Theoretical models are developed to account for some of the observed aberrations.

  6. Continuously variable focal length lens

    DOEpatents

    Adams, Bernhard W; Chollet, Matthieu C

    2013-12-17

    A material preferably in crystal form having a low atomic number such as beryllium (Z=4) provides for the focusing of x-rays in a continuously variable manner. The material is provided with plural spaced curvilinear, optically matched slots and/or recesses through which an x-ray beam is directed. The focal length of the material may be decreased or increased by increasing or decreasing, respectively, the number of slots (or recesses) through which the x-ray beam is directed, while fine tuning of the focal length is accomplished by rotation of the material so as to change the path length of the x-ray beam through the aligned cylindrical slows. X-ray analysis of a fixed point in a solid material may be performed by scanning the energy of the x-ray beam while rotating the material to maintain the beam's focal point at a fixed point in the specimen undergoing analysis.

  7. Optical system design of solar-blind UV target simulator with long focal length

    NASA Astrophysics Data System (ADS)

    Chen, Yu; Huo, Furong; Zheng, Liqin

    2014-11-01

    Ultraviolet (UV) radiation of 200nm-300nm waveband from the sun is absorbed by atmosphere, which is often referred to the solar-blind region of the solar spectrum. Solar-blind characteristics of this waveband have important application value, especially in military fields. The application of solar-blind waveband has developed very rapidly, which is receiving more and more attention. Sometimes, to test the performance of a UV optical system, a standard solar-blind UV target simulator is needed as the UV light source. In this paper, an optical system of a solar-blind UV target simulator is designed with waveband 240nm-280nm. To simulate a far UV target, the focal length of this UV optical system needs to be long. Besides, different field of view (FOV) of the system should meet aplanatic condition. The optional materials are very few for UV optical systems, in which only CaF2 and JGS1 are commonly used. Various aberrations are difficult to be corrected. To save production cost and enhance the precision of fabrication and test, aspheric surfaces and binary elements are not adopted in the system. Moreover, doublet or triplet cannot be used in UV optical system considering possible cracking for different thermal expansion coefficients of different materials. After optimization, the system is composed of 4 lenses with focal length 500mm. MTF curves of different FOV coincide together. The maximum RMS radius of the optimized system has almost the same size as Airy disk, which proves the good image quality after system optimization. The aplanatic condition is met very well in this system. In the spot diagram, root mean square (RMS) radius changes from 3 microns to 3.6 microns, which has similar size with Airy disk and meets aplanatic condition very well. This optical system of solar-blind UV target simulator also has relatively loose tolerance data, which can prove the system is designed in an optimal state.

  8. Variable focal length deformable mirror

    DOEpatents

    Headley, Daniel (Albuquerque, NM); Ramsey, Marc (Albuquerque, NM); Schwarz, Jens (Albuquerque, NM)

    2007-06-12

    A variable focal length deformable mirror has an inner ring and an outer ring that simply support and push axially on opposite sides of a mirror plate. The resulting variable clamping force deforms the mirror plate to provide a parabolic mirror shape. The rings are parallel planar sections of a single paraboloid and can provide an on-axis focus, if the rings are circular, or an off-axis focus, if the rings are elliptical. The focal length of the deformable mirror can be varied by changing the variable clamping force. The deformable mirror can generally be used in any application requiring the focusing or defocusing of light, including with both coherent and incoherent light sources.

  9. Nano-optical microlens with ultrashort focal length using negative refraction

    E-print Network

    Sridhar, Srinivas

    -optical microlenses can be integrated into existing semiconductor heterostructure platforms for next, nanofabri- cated in an InP/InGaAsP semiconductor heterostructure plat- form. Dispersion engineering princi microlens in an InP/ InGaAsP semiconductor two-dimensional 2D photonic crystal with negative index

  10. Microlenses with focal length controlled by chemical processes

    NASA Astrophysics Data System (ADS)

    Muric, B. D.; Panic, B. M.

    2012-05-01

    The influence of chemical processing on the optical properties of microlenses formed on a gelatin-sensitized layer was investigated. The gelatin is sensitized with tot'hema and eosin, irradiated with a Gaussian profile laser beam and subsequently chemically processed. Microlenses with a focal length of 400??m were obtained after alcohol processing. Additionally, focal lengths could be controlled by varying the alum concentration, and lenses with focal length up to 1.2?mm were obtained. The microlenses become stable after alum processing. Their optical properties remain unchanged.

  11. Optofluidic lens with tunable focal length and asphericity

    PubMed Central

    Mishra, Kartikeya; Murade, Chandrashekhar; Carreel, Bruno; Roghair, Ivo; Oh, Jung Min; Manukyan, Gor; van den Ende, Dirk; Mugele, Frieder

    2014-01-01

    Adaptive micro-lenses enable the design of very compact optical systems with tunable imaging properties. Conventional adaptive micro-lenses suffer from substantial spherical aberration that compromises the optical performance of the system. Here, we introduce a novel concept of liquid micro-lenses with superior imaging performance that allows for simultaneous and independent tuning of both focal length and asphericity. This is achieved by varying both hydrostatic pressures and electric fields to control the shape of the refracting interface between an electrically conductive lens fluid and a non-conductive ambient fluid. Continuous variation from spherical interfaces at zero electric field to hyperbolic ones with variable ellipticity for finite fields gives access to lenses with positive, zero, and negative spherical aberration (while the focal length can be tuned via the hydrostatic pressure). PMID:25224851

  12. Multilayer Laue Lenses with Focal Length of 10 mm

    NASA Astrophysics Data System (ADS)

    Braun, S.; Kubec, A.; Menzel, M.; Niese, S.; Krüger, P.; Seiboth, F.; Patommel, J.; Schroer, C.

    2013-03-01

    Multilayer laue lenses are diffractive optics with a high potential for producing X-ray foci in the order of 10 nm or even below. Particularly for hard X-rays (E > 6 keV) these optics promise better resolution and higher efficiencies than currently available Fresnel zone plates. Magnetron sputter deposition has been used for the fabrication of multilayer laue lenses using the layer materials MoSi2 and Si. The lens design has been defined to get focal length in the order of 10 mm. One of the lenses with an aperture of about 20 ?m has been used as focusing optics in the nanoprobe beamline P06 at PETRA III. Ptychography has been applied to characterize the caustic of the focused beam and to determine the size of the X-ray focus. A spot size of about 39 nm could be obtained with a photon energy of 21 keV and a focal length of 9.9 mm.

  13. Acoustic lens with variable focal length for photoacoustic microscopy

    NASA Astrophysics Data System (ADS)

    Song, Chaolong; Xi, Lei; Jiang, Huabei

    2013-11-01

    A liquid acoustic lens with variable focal length is described for photoacoustic microscopy. This liquid lens takes advantage of the elastic and deformable lens interface to tune its focal length in a pneumatical manner. The curvature of the lens interface as well as the dependant focal length was characterized as a function of the infusion volume of the liquid. Experiments were carried out to demonstrate the zooming ability of this liquid acoustic lens. Targets embedded at different depths were photoacoustically imaged without performing mechanically axial scanning.

  14. Long Focal Length Large Mirror Fabrication System

    NASA Technical Reports Server (NTRS)

    Bennett, H. E.

    2003-01-01

    The goals of this ambitious program are (1) to develop systems to make large superpolished optical mirrors, (2) to develop low scatter polishing techniques using centrifugal elutriation, (3) to develop a means of measuring scatter at any point on the mirror, (4) to polish a Hindle sphere to measure the optical figure of a one meter diameter convex mandrel, and (5) to fabricate low scatter, large adaptive optic graphite filled, cyanate ester replica transfer mirrors using these mandrels. Deliverables are a 30 cm diameter superpolished composite AO mirror. We fabricated a 1/3rd meter superpolished zerodur flat mandrel and with the support of our major subcontractor, Composite Mirror Applications Inc (CMA) we have demonstrated a 30 cm lightweight cyanate ester mirror with an rms microroughness between 0.6 and 0.8 nm and 8 faceplate influence function of 5 cm. The influence function was chosen to be comparable to the atmospheric correlation coefficient r(sub 0) which is about 5 cm at sea level. There was no print-thru of the graphite fibers in the cyanate ester surface (the bane of many previous efforts to use cyanate ester mirrors). Our subcontractor has devised a means for developing a 30-50 nm thick layer of graphite free pure ester resin on the surface of the mirrors. This graphite fiber filled material has a thermal expansion coefficient in the 10(exp -8) centimeter per Kelvin range (the same range of expansion coefficient as Zerodur and ULE glasses) and does not take up water and swell, so it is a nearly ideal mirror material in these areas. Unfortunately for these 0.8mm thick faceplates, the number of plies is not enough to result in isometric coverage. Isolated figure irregularities can appear, making it necessary to go to thicker faceplates. The influence function will then only approximate the length of r(sub 0), at higher altitudes or longer wavelengths. The influence function goes as the cube of the thickness, so we are now making a faceplate optimized for an infrared wavelength, possibly that used for the AO system of the Keck telescope, instead of 0.63 microns. We have polished a 55 cm diameter mandrel to better than 1/20th wave optical figure in the visible using centrifugal elutriation. CMA has just told us that it needs to retool to get optimum mirror faceplate quality in this size, so implementing the 55 cm AO mirror may be delayed somewhat. We expect to complete our 1/3 rd meter AO mirror on time using novel piezoelectric actuators with a throw of one micrometer per volt, as compared to 0.005 micrometers per volt for conventional piezoelectric actuators. We will then demonstrate its AO performance interferometrically.

  15. Biomimetic small scale variable focal length lens unit using synthetic elastomer actuators

    NASA Astrophysics Data System (ADS)

    Kim, Baek-chul; Chung, Jinah; Lee, Y.; Nam, Jae-Do; Moon, Hyungpil; Choi, Hyouk Ryeol; Koo, J. C.

    2011-04-01

    Having a combination of a gel-like soft lens, ligaments, and the Ciliary muscles, the human eyes are effectively working for various focal lengths without a complicated group of lens. The simple and compact but effective optical system should deserve numerous attentions from various technical field especially portable information technology device industry. Noting the limited physical space of those deivces, demanding shock durability, and massive volume productivity, the present paper proposes a biomimetic optical lens unit that is organized with a circular silicone lens and an annular dielectric polymer actuator. Unlike the traditional optical lens mechanism that normally acquires a focus by changing its focal distance with moving lens or focal plane. the proposed optical system changes its lens thickness using a annulary connected polymer actuator in order to get image focuses. The proposed biomimetic lens system ensures high shock durability, compact physical dimensions, fast actuations, simple manufacturing process, and low production cost.

  16. Shaping a Subwavelength Needle with Ultra-long Focal Length by Focusing Azimuthally Polarized Light

    PubMed Central

    Qin, Fei; Huang, Kun; Wu, Jianfeng; Jiao, Jiao; Luo, Xiangang; Qiu, Chengwei; Hong, Minghui

    2015-01-01

    Flat optics, which could planarize and miniaturize the traditional optical elements, possesses the features of extremely low profile and high integration for advanced manipulation of light. Here we proposed and experimentally demonstrated a planar metalens to realize an ultra-long focal length of ~240? with a large depth of focus (DOF) of ~12?, under the illumination of azimuthally polarized beam with vortical phase at 633 nm. Equally important is that such a flat lens could stably keep a lateral subwavelength width of 0.42? to 0.49? along the needle-like focal region. It exhibits one-order improvement in the focal length compared to the traditional focal lengths of 20~30? of flat lens, under the criterion of having subwavelength focusing spot. The ultra-long focal length ensures sufficient space for subsequent characterization behind the lens in practical industry setups, while subwavelength cross section and large DOF enable high resolution in transverse imaging and nanolithography and high tolerance in axial positioning in the meantime. Such planar metalens with those simultaneous advantages is prepared by laser pattern generator rather than focused ion beam, which makes the mass production possible. PMID:25943500

  17. Shaping a Subwavelength Needle with Ultra-long Focal Length by Focusing Azimuthally Polarized Light.

    PubMed

    Qin, Fei; Huang, Kun; Wu, Jianfeng; Jiao, Jiao; Luo, Xiangang; Qiu, Chengwei; Hong, Minghui

    2015-01-01

    Flat optics, which could planarize and miniaturize the traditional optical elements, possesses the features of extremely low profile and high integration for advanced manipulation of light. Here we proposed and experimentally demonstrated a planar metalens to realize an ultra-long focal length of ~240? with a large depth of focus (DOF) of ~12?, under the illumination of azimuthally polarized beam with vortical phase at 633 nm. Equally important is that such a flat lens could stably keep a lateral subwavelength width of 0.42? to 0.49? along the needle-like focal region. It exhibits one-order improvement in the focal length compared to the traditional focal lengths of 20~30? of flat lens, under the criterion of having subwavelength focusing spot. The ultra-long focal length ensures sufficient space for subsequent characterization behind the lens in practical industry setups, while subwavelength cross section and large DOF enable high resolution in transverse imaging and nanolithography and high tolerance in axial positioning in the meantime. Such planar metalens with those simultaneous advantages is prepared by laser pattern generator rather than focused ion beam, which makes the mass production possible. PMID:25943500

  18. Ultra-Light Electromagnetic Wave Concentrator with Variable Focal Length

    NASA Astrophysics Data System (ADS)

    Sahara, Hironori; Ezaki, Shinsuke; Shimizu, Morio; Nakamura, Yoshihiro

    2003-04-01

    In this paper, we present an ultra-light electromagnetic wave concentrator with a variable focal length (EMC/VFL), and its representative applications to a solar ray concentrator for solar thermal propulsion (STP) and solar power station (SPS). The EMC/VFL consists of a pair of rectangular reflectors of ultra-light thin materials such as reflective polymer membrane, each of which has a line focus due to appropriate bending moment and axial force. The variable bending moment and axial force make the reflector a highly precise paraboloidal concentrator with variable focal length, and its characteristics as a concentrator are estimated by calculation. The two focal lines intersect each other perpendicularly so that a point focus can be formed at the intersection. Unlike a conventional paraboloidal concentrator including an inflatable type, the EMC/VFL can be folded very compactly, and hence an extremely wide area for an electromagnetic wave receiver would be available in space. Because of its variable focal length, applications in various fields are possible, as a radar antenna with variable gains, a solar furnace with variable heating patterns, and a concentrator for STP or SPS with variable solar image, especially in space due to its very high level of compactness.

  19. High speed multi focal plane optical system

    Microsoft Academic Search

    P. O. Minott

    1983-01-01

    An apparatus for eliminating beamsplitter generated optical aberrations in a pupil concentric optical system providing a plurality of spatially separated images on different focal planes or surfaces is presented. The system employs a buried surface beamsplitter having spherically curved entrance and exit faces which are concentric to a system aperture stop with the entrance face being located in the path

  20. Exhaustive Linearization for Robust Camera Pose and Focal Length Estimation.

    PubMed

    Penate-Sanchez, Adrian; Andrade-Cetto, Juan; Moreno-Noguer, Francesc

    2013-01-30

    We propose a novel approach for the estimation of the pose and focal length of a camera from a set of 3D-to-2D point correspondences. Our method compares favorably to competing approaches in that it is both more accurate than existing closed form solutions, as well as faster and also more accurate than iterative ones. Our approach is inspired on the EPnP algorithm, a recent O(n) solution for the calibrated case. Yet, we show that considering the focal length as an additional unknown renders the linearization and relinearization techniques of the original approach no longer valid, especially with large amounts of noise. We present new methodologies to circumvent this limitation termed exhaustive linearization and exhaustive relinearization which perform a systematic exploration of the solution space in closed form. The method is evaluated on both real and synthetic data, and our results show that besides producing precise focal length estimation, the retrieved camera pose is almost as accurate as the one computed using the EPnP, which assumes a calibrated camera. PMID:23382296

  1. Exhaustive linearization for robust camera pose and focal length estimation.

    PubMed

    Penate-Sanchez, Adrian; Andrade-Cetto, Juan; Moreno-Noguer, Francesc

    2013-10-01

    We propose a novel approach for the estimation of the pose and focal length of a camera from a set of 3D-to-2D point correspondences. Our method compares favorably to competing approaches in that it is both more accurate than existing closed form solutions, as well as faster and also more accurate than iterative ones. Our approach is inspired on the EPnP algorithm, a recent O(n) solution for the calibrated case. Yet we show that considering the focal length as an additional unknown renders the linearization and relinearization techniques of the original approach no longer valid, especially with large amounts of noise. We present new methodologies to circumvent this limitation termed exhaustive linearization and exhaustive relinearization which perform a systematic exploration of the solution space in closed form. The method is evaluated on both real and synthetic data, and our results show that besides producing precise focal length estimation, the retrieved camera pose is almost as accurate as the one computed using the EPnP, which assumes a calibrated camera. PMID:23969384

  2. Optical interconnections to focal plane arrays

    SciTech Connect

    Rienstra, J.L.; Hinckley, M.K.

    2000-11-01

    The authors have successfully demonstrated an optical data interconnection from the output of a focal plane array to the downstream data acquisition electronics. The demonstrated approach included a continuous wave laser beam directed at a multiple quantum well reflectance modulator connected to the focal plane array analog output. The output waveform from the optical interconnect was observed on an oscilloscope to be a replica of the input signal. They fed the output of the optical data link to the same data acquisition system used to characterize focal plane array performance. Measurements of the signal to noise ratio at the input and output of the optical interconnection showed that the signal to noise ratio was reduced by a factor of 10 or more. Analysis of the noise and link gain showed that the primary contributors to the additional noise were laser intensity noise and photodetector receiver noise. Subsequent efforts should be able to reduce these noise sources considerably and should result in substantially improved signal to noise performance. They also observed significant photocurrent generation in the reflectance modulator that imposes a current load on the focal plane array output amplifier. This current loading is an issue with the demonstrated approach because it tends to negate the power saving feature of the reflectance modulator interconnection concept.

  3. Pose Estimation with Unknown Focal Length using Points, Directions and Lines Yubin Kuang, Kalle Astrom

    E-print Network

    Lunds Universitet

    Pose Estimation with Unknown Focal Length using Points, Directions and Lines Yubin Kuang, Kalle In this paper, we study the geometry problems of esti- mating camera pose with unknown focal length using com enables robust pose estimation with unknown focal length for wider classes of features. Such rich features

  4. High speed multi focal plane optical system

    NASA Technical Reports Server (NTRS)

    Minott, P. O. (inventor)

    1983-01-01

    An apparatus for eliminating beamsplitter generated optical aberrations in a pupil concentric optical system providing a plurality of spatially separated images on different focal planes or surfaces is presented. The system employs a buried surface beamsplitter having spherically curved entrance and exit faces which are concentric to a system aperture stop with the entrance face being located in the path of a converging light beam directed there from an image forming objective element which is also concentric to the aperture stop.

  5. Simple focal-length measurement technique with a circular Dammann grating

    SciTech Connect

    Zhao Shuai; Wen, J.F.; Chung, P.S

    2007-01-01

    A novel technique for focal-length measurements with a circular Dammann grating is presented. In the back focal plane of the lens under test, a one-order circular Dammann grating with limited aperture will produce double-humped radial rings. The separation between the two lobes varies with the displacement of the observed plane from the focal plane of the lens. By searching for the position at which the separation is minimal, the focal point of the lens can be located and hence the back focal length can be determined. Experimental results demonstrated that this method is efficient and can be used effectively for a quick check of focal length.

  6. Analysis of difference in orientations and focal lengths of two arbitrary perspective viewing cameras

    NASA Astrophysics Data System (ADS)

    Ramachandran, Aishwarya; Balasubramanian, R.; Swaminathan, K.; Das, Sukhendu

    2007-01-01

    For stereo imaging, it is a general practice to use two cameras of same focal lengths, with their viewing axis normal to the line joining the camera centres. This paper analyses the result of difference in orientations and focal lengths of two arbitrary prespective viewing cameras, by deriving the epipolar lines and its correspoinding equations. This enables one to find the correspondence search space in terms of focal length accuracies as well as camera orientation parameteres. Relevant numerically simulated results are also given.

  7. The Modernization of a Long-Focal Length Fringe-Type Laser Velocimeter

    NASA Technical Reports Server (NTRS)

    Meyers, James F.; Lee, Joseph W.; Cavone, Angelo A.; Fletcher, Mark T.

    2012-01-01

    A long-focal length laser velocimeter constructed in the early 1980's was upgraded using current technology to improve usability, reliability and future serviceability. The original, free-space optics were replaced with a state-of-the-art fiber-optic subsystem which allowed most of the optics, including the laser, to be remote from the harsh tunnel environment. General purpose high-speed digitizers were incorporated in a standard modular data acquisition system, along with custom signal processing software executed on a desktop computer, served as the replacement for the signal processors. The resulting system increased optical sensitivity with real-time signal/data processing that produced measurement precisions exceeding those of the original system. Monte Carlo simulations, along with laboratory and wind tunnel investigations were used to determine system characteristics and measurement precision.

  8. Simple focal-length measurement technique with a circular Dammann grating.

    PubMed

    Zhao, Shuai; Wen, Jacky Fung; Chung, Po Sheun

    2007-01-01

    A novel technique for focal-length measurements with a circular Dammann grating is presented. In the back focal plane of the lens under test, a one-order circular Dammann grating with limited aperture will produce double-humped radial rings. The separation between the two lobes varies with the displacement of the observed plane from the focal plane of the lens. By searching for the position at which the separation is minimal, the focal point of the lens can be located and hence the back focal length can be determined. Experimental results demonstrated that this method is efficient and can be used effectively for a quick check of focal length. PMID:17167552

  9. Controllable focal spot for direct-drive laser fusion based on electro-optic effect

    NASA Astrophysics Data System (ADS)

    Zhong, Zheqiang; Hu, Xiaochun; Li, Zelong; Ye, Rong; Zhang, Bin

    2014-09-01

    In direct-drive laser fusion, the sufficient uniformity of focal spot for realizing high efficient compression and central ignition is required. However, the laser beams are difficult to achieve sufficient uniform for compressing the shell symmetrically inward. We proposed a novel scheme to achieve controllable focal length based on electro-optic effect. The electro-optic crystal was placed in the front of the laser fusion system and applied the electro field with approximate spherical distribution. Since the wavefront of laser beam is transformed through the electro-optic crystal, the focal spot of the transformed laser beam would be changed on the target. Theoretical analysis and numerical simulation have been made, and the results show that the proposed scheme could achieve enough controllable focal spot on the target.

  10. Embedding perspective cue in holographic projection display by virtual variable-focal-length lenses

    NASA Astrophysics Data System (ADS)

    Li, Zhaohui; Zhang, Jianqi; Wang, Xiaorui; Zhao, Fuliang

    2014-10-01

    To make a view perspective cue emerging in reconstructed images, a new approach is proposed by incorporating virtual variable-focal-length lenses into computer generated Fourier hologram (CGFH). This approach is based on a combination of monocular vision principle and digital hologram display, thus it owns properties coming from the two display models simultaneously. Therefore, it can overcome the drawback of the unsatisfied visual depth perception of the reconstructed three-dimensional (3D) images in holographic projection display (HPD). Firstly, an analysis on characteristics of conventional CGFH reconstruction is made, which indicates that a finite depthof- focus and a non-adjustable lateral magnification are reasons of the depth information lack on a fixed image plane. Secondly, the principle of controlling lateral magnification in wave-front reconstructions by virtual lenses is demonstrated. And the relation model is deduced, involving the depth of object, the parameters of virtual lenses, and the lateral magnification. Next, the focal-lengths of virtual lenses are determined by considering perspective distortion of human vision. After employing virtual lenses in the CGFH, the reconstructed image on focal-plane can deliver the same depth cues as that of the monocular stereoscopic image. Finally, the depthof- focus enhancement produced by a virtual lens and the effect on the reconstruction quality from the virtual lens are described. Numerical simulation and electro-optical reconstruction experimental results prove that the proposed algorithm can improve the depth perception of the reconstructed 3D image in HPD. The proposed method provides a possibility of uniting multiple display models to enhance 3D display performance and viewer experience.

  11. Thermal considerations in the design of a long focal length, low f-number, long wave infrared imager

    NASA Astrophysics Data System (ADS)

    Spencer, Harvey M.

    2010-08-01

    Sensors operating in the 8-12 micron long wave infrared (LWIR) portion of the electromagnetic spectrum have long been used to extend the useful range of operating conditions beyond those of sensor systems operating in the visual spectral band. Infrared systems must cover widely varying fields-of-view (FOV) depending on application, at fast f/numbers compared to systems operating in the visible band. Typical FOVs for LWIR sensors run the gamut from < 1 degree to >50 degrees for large focal planes, necessitating the use of long focal lengths. When the focal length of the optics increases, the sensitivity to defocus caused by thermal effects also increases. Optical materials with useful transmission in the infrared region exhibit larger changes (> 400X) in refractive index with temperature (dN/dT) than optical glass. This in turn introduces larger changes in focus over temperature for infrared systems compared to comparable focal length visual systems. Thermal expansion and contraction of the materials also contribute to changes in system performance and the coefficient of thermal expansion (CTE) is generally larger for infrared materials than for visual band optical glasses. The thermal performance problem is exacerbated with low f-numbers systems. The ability to detect targets having a small temperature difference from ambient is proportional to the light collecting ability of the optics, especially when uncooled detectors are used. It is typical to require f-numbers in the f/1 regime for the LWIR for uncooled applications. Methods have been developed to find optical designs with reduced thermal sensitivity for these applications.

  12. Euclidean Reconstruction from Image Sequences with Varying and Unknown Focal Length and Principal Point

    E-print Network

    Lunds Universitet

    Euclidean Reconstruction from Image Sequences with Varying and Unknown Focal Length and Principal. These type of cameras, here called cameras with Euclidean image pla- nes, represent rigid projections where to reconstruct an unknown object from images taken by a camera with Euclidean image plane up to simi- larity

  13. Euclidean Reconstruction from Image Sequences with Varying and Unknown Focal Length and Principal Point

    Microsoft Academic Search

    Anders Heyden; Kalle Åström

    1997-01-01

    In this paper the special case of reconstruction from image sequences taken by cameras with skew equal to0 and aspect ratio equal to 1 has been treated. These type of cameras, here called cameras with Euclidean image pla- nes, represent rigid projections where neither the principal point nor the focal length is known. It will be shown that it is

  14. Focal Plane Alignment Utilizing Optical CMM

    NASA Technical Reports Server (NTRS)

    Liebe, Carl Christian; Meras, Patrick L.; Clark, Gerald J.; Sedaka, Jack J.; Kaluzny, Joel V.; Hirsch, Brian; Decker, Todd A.; Scholtz, Christopher R.

    2012-01-01

    In many applications, an optical detector has to be located relative to mechanical reference points. One solution is to specify stringent requirements on (1) mounting the optical detector relative to the chip carrier, (2) soldering the chip carrier onto the printed circuit board (PCB), and (3) installing the PCB to the mechanical structure of the subsystem. Figure 1 shows a sketch of an optical detector mounted relative to mechanical reference with high positional accuracy. The optical detector is typically a fragile wafer that cannot be physically touched by any measurement tool. An optical coordinate measuring machine (CMM) can be used to position optical detectors relative to mechanical reference points. This approach will eliminate all requirements on positional tolerances. The only requirement is that the PCB is manufactured with oversized holes. An exaggerated sketch of this situation is shown in Figure 2. The sketch shows very loose tolerances on mounting the optical detector in the chip carrier, loose tolerance on soldering the chip carrier to the PCB, and finally large tolerance on where the mounting screws are located. The PCB is held with large screws and oversized holes. The PCB is mounted loosely so it can move freely around. The optical CMM measures the mechanical reference points. Based on these measurements, the required positions of the optical detector corners can be calculated. The optical CMM is commanded to go to the position where one detector corner is supposed to be. This is indicated with the cross-hairs in Figure 2(a). This figure is representative of the image of the optical CMM monitor. Using a suitable tapping tool, the PCB is manually tapped around until the corner of the optical detector is at the crosshairs of the optical CMM. The CMM is commanded to another corner, and the process is repeated a number of times until all corners of the optical detector are within a distance of 10 to 30 microns of the required position. The situation is sketched in Figure 2(b) (the figure also shows the tapping tool and where to tap). At this point the fasteners for the PCB are torqued slightly so the PCB can still move. The PCB location is adjusted again with the tapping tool. This process is repeated 3 to 4 times until the final torque is achieved. The oversized mounting holes are then filled with a liquid bonding agent to secure the board in position (not shown in the sketch). A 10- to 30-micron mounting accuracy has been achieved utilizing this method..

  15. The Solar-B Solar Optical Telescope Focal Plane Package

    Microsoft Academic Search

    M. Levay; T. Berger; W. Rosenberg; T. Tarbell; T. Bogdan; D. Elmore; B. Lites

    1999-01-01

    The primary goal of the Solar-B mission is to understand the physical processes responsible for dynamics and heating of the outer solar atmosphere. The Focal Plane Package (FPP) instrument for the 50-cm Solar Optical Telescope provides precise measurements of the vector magnetic field, vertical and horizontal flows, and thermal conditions in the photosphere and low chromosphere with spatial resolution as

  16. Comparison of variable and fixed focal length cone beam CT in diagnostic imaging

    NASA Astrophysics Data System (ADS)

    LaRoque, Samuel J.; Bian, Junguo; Sidky, Emil Y.; Pan, Xiaochuan

    2008-03-01

    We use a task-based study to objectively evaluate the effect of variable versus fixed focal length in determining the position of a lesion in helical cone-beam computed tomography (HCBCT). This method will be used to assess whether variable focal length CBCT scans provide a measurable improvement in estimating lesion position relative to fixed focal length CBCT in diagnostic applications. In this simulation study a 1 cm diameter spherical lesion is placed at four different positions within a three-dimensional Shepp-Logan head phantom. The axial plane is taken to point along the z-axis, which is also the central axis of the helix. The lesion is placed at the center of the Shepp-Logan phantom, at positions displaced +/-5 cm in x, and at a position displaced 5 cm in y. Four different scans of pitch length 10 cm are then performed using 128 views over 360° with a 100×300 pixel (20 cm×60 cm) detector. Two scans have a fixed focal length of 50 cm between the X-ray source and the center of rotation (COR), varying only in the starting angle of the source (0° and 90°). We call this the circular configuration. The other two scans have a variable focal length following the curvature of the head phantom and ranging from 37.5 cm to 50 cm. We call this the elliptical configuration. The detector rotates with the source but maintains a constant distance of 30 cm from the COR. A likelihood gridding technique is used to assess bias and variance in the position estimates determined from each scan configuration. We find that the biases are small relative to the variances, and have no apparent preferred direction. Of the 24 circular to elliptical comparisons made, we find that in 14 cases the elliptical scan has a smaller variance that is statistically significant(p <= 0.05). By contrast, we find no statistically significant cases in which the circular scan gives a smaller variance compared to the elliptical scan. We conclude that using a variable focal length adapted to the contours of the head phantom provides more precise results, but caution that this is a limited pilot study and many more factors will be accounted for in future work.

  17. Focal length measurement of a microlens-array by grating shearing interferometry.

    PubMed

    Zhu, Xianchang; Hu, Song; Zhao, Lixin

    2014-10-10

    Based on grating shearing interferometry, a simple technique is introduced for focal length measurements of a microlens-array (MLA). The measurement system is composed of a He-Ne laser, condenser, collimator, the MLA under testing, a Ronchi grating, and CCD sensor. The plane wavefront from the collimator is transformed to a spherical wavefront by the MLA, while the curvature center is at the focus. Interference stripes appear at the overlap between the zero-order and first-order diffractive patterns of the grating and are detected by the CCD sensor. By analyzing the period change of stripes, the focal length is determined after the defocus of the grating is calculated. To validate the feasibility, an experiment is performed. The measurement uncertainty is discussed and measurement accuracy was determined to be 2%. PMID:25322367

  18. Deformation and focal length analysis of electrostatic actuated micro deformable mirror

    Microsoft Academic Search

    Meng-Ju Lin; Ko-Wei Wu; Shih-Hsiung Huang

    2010-01-01

    In this work, deformation and focal length of a circular shape micro deformable mirror under different applying voltage is analyzed. This mirror has round shape. And it is circular clamped. In this work, the mirror is designed as MEMS (Micro-electro-mechanical systems) device. Therefore, it is considered to be fabricated by silicon-based micromachining. Such that, the material used as structure layer

  19. Multi-focal spherical media and geodesic lenses in geometrical optics

    E-print Network

    Tyc, Tomas

    Multi-focal spherical media and geodesic lenses in geometrical optics Martin Sarbort1 and Tom optics arXiv:1305.0696v1[physics.optics]3May2013 #12;Multi-focal spherical media and geodesic lenses optics. For example, we mention the spherical gradient-index lenses embedded into an optically

  20. Meeting the Optical Requirements of Large Focal-Plane Arrays

    E-print Network

    Antony A. Stark

    2003-05-29

    Technological advances will allow the placement of many Terahertz detectors at the focal plane of a single telescope. For a telescope of a given diameter and wavelength of operation, there is a limit to the number of usable detectors imposed by diffraction and optical aberrations. These effects can be ameliorated through an optical design where the magnification of the telescope's secondary mirror is small and the detector package is therefore located near the secondary mirror. A field mirror can be used to flatten the image, and the focal reducer which matches the detector to the telescope can also provide an image of the aperture for placement of filters and stops. A design concept is presented for the South Pole Telescope which comprises a 10-meter diameter off-axis paraboloidal primary mirror, a Gregorian secondary mirror, a tertiary chopper, dewar widow, Lyot stops, band-pass filter, and space behind the focal plane for cryogenics. The telescope is bilaterally symmetric, and all apertures are unblocked. The field of view is one degree in diameter, so this telescope can feed an array of several tens of thousands of detectors at Terahertz frequencies.

  1. The influence of beam energy, mode and focal length on the control of laser ignition in an internal combustion engine

    Microsoft Academic Search

    J. D. Mullett; R. Dodd; C. J. Williams; G. Triantos; G. Dearden; A. T. Shenton; K. G. Watkins; S. D. Carroll; A. D. Scarisbrick; S. Keen

    2007-01-01

    This work involves a study on laser ignition (LI) in an internal combustion (IC) engine and investigates the effects on control of engine combustion performance and stability of varying specific laser parameters (beam energy, beam quality, minimum beam waist size, focal point volume and focal length). A Q-switched Nd : YAG laser operating at the fundamental wavelength 1064 nm was

  2. Three-dimensional fiber probe based on micro focal-length collimation and a fiber Bragg grating for the measurement of micro parts.

    PubMed

    Cui, Jiwen; Li, Junying; Feng, Kunpeng; Tan, Jiubin

    2015-07-15

    A three-dimensional (3D) fiber probe is proposed for the measurement of micro parts. The probe is made of a fiber Bragg grating (FBG) that acts as a micro focal-length cylindrical lens (MFLC-lens) of two mutually orthogonal micro focal-length collimation (MFL-collimation) optical paths. The radial displacement of the probe tip is transformed into the shift of the fringe image collimated by the MFL-collimation optical path; the axial displacement of the probe tip is transformed into the power ratio variation caused by the Bragg wavelength shift. Advantages of the probe are high precision, low cost, high measurable aspect ratio, and capability of decoupling the 3D tactility. PMID:26176466

  3. Graded negative index lens with designable focal length by phononic crystal

    E-print Network

    Deng, Ke; He, Zhaojian; Liu, Zhengyou; Zhao, Heping; Shi, Jing

    2009-01-01

    We realize a flat lens with graded negative refractive index by a two-dimensional phononic crystal. The index-grade is achieved by gradual modification of the filling fraction along the transverse direction to propagation. We demonstrate that this lens can realize the focusing and amplification of parallel incident acoustic waves. A formula for the refractive index profile is derived by which the lens with desired focal length can be precisely designed and the aberrations of image can be effectively reduced. This designable lens is expected to bear significance in applications such as coupling or integration with various types of acoustic devices.

  4. Light sources generating self-focusing beams of variable focal length.

    PubMed

    Mei, Zhangrong

    2014-01-15

    A class of partially coherent beams with a nonuniformly cosine-Gaussian (NUCG) correlated function is introduced. The evolution behavior of scalar beams produced by these families of sources in free space and isotropic random media are investigated. It is shown that such light fields with NUCG correlated function propagating in free space and turbulent atmosphere have self-focusing effects and laterally shifted intensity maxima. The new source employs cosine function for modeling of the source degree of coherence, which can adjust the self-focusing focal length, the shift of intensity center, and the intensity profile. PMID:24562143

  5. Optimization-free optical focal field engineering through reversing the radiation pattern from a uniform line source.

    PubMed

    Yu, Yanzhong; Zhan, Qiwen

    2015-03-23

    A simple and flexible method is presented for the generation of optical focal field with prescribed characteristics. By reversing the field pattern radiated from a uniform line source, for which the electric current is constant along its extent, situated at the focus of a 4Pi focusing system formed by two confocal high-NA objective lenses, the required illumination distribution at the pupil plane for creating optical focal field with desired properties can be obtained. Numerical example shows that an arbitrary length optical needle with extremely high longitudinal polarization purity and consistent transverse size of ~0.36? over the entire depth of focus (DOF) can be created with this method. Coaxially double-focus with spot size of ~0.36? in the transversal direction and ~? in the axial direction separated by a prescribed spacing is illustrated as another example. The length of optical needle field and the interval between double-focus are determined by the length of uniform line source. These engineered focal fields may found potential applications in particle acceleration, optical microscopy, optical trapping and manipulations. PMID:25837091

  6. Focal-Plane Image and Beam Quality Sensors for Adaptive Optics

    E-print Network

    Cauwenberghs, Gert

    Focal-Plane Image and Beam Quality Sensors for Adaptive Optics Marc CohenÝ, Gert Cauwenberghs Laboratory, Adelphi, MD 20783 Abstract Control of adaptive optical elements for real-time wavefront phase to the requirements of high resolution, real-time adaptive optical systems. In this paper we introduce two VLSI focal

  7. Cryogenic focal plane flatness measurement with optical zone slope Jerry Edelstein1

    E-print Network

    California at Berkeley, University of

    Cryogenic focal plane flatness measurement with optical zone slope tracking Jerry Edelstein1 to determine the surface flatness of a cryogenic sensor array developed for the JDEM mission. Large focal such as JDEM, WFIRST, or EUCLID must operate at cryogenic temperatures while maintaining focal plane flatness

  8. Multiple-Path-Length Optical Absorbance Cell

    NASA Technical Reports Server (NTRS)

    2001-01-01

    An optical absorbance cell that offers a selection of multiple optical path lengths has been developed as part of a portable spectrometric instrument that measures absorption spectra of small samples of water and that costs less than does a conventional, non-portable laboratory spectrometer. The instrument is intended, more specifically, for use in studying colored dissolved organic matter (CDOM) in seawater, especially in coastal regions. Accurate characterization of CDOM is necessary for building bio-optical mathematical models of seawater. The multiple path lengths of the absorption cell afford a wide range of sensitivity needed for measuring the optical absorbances associated with the wide range of concentrations of CDOM observed in nature. The instrument operates in the wavelength range of 370 to 725 nm. The major subsystems of the instrument (see figure) include a color-balanced light source; the absorption cell; a peristaltic pump; a high-precision, low-noise fiber optic spectrometer; and a laptop or other personal computer. A fiber-optic cable transmits light from the source to the absorption cell. Other optical fibers transmit light from the absorption cell to the spectrometer,

  9. Modeling of a Variable Focal Length Flat Lens Using Left Handed Metamaterials

    NASA Technical Reports Server (NTRS)

    Reinert, Jason

    2004-01-01

    Left Handed Metamaterials (LHM) were originally purposed by Victor Veselago in1968. These substances would allow a flat structure to focus electromagnetic (EM) waves because they have a negative index of refraction. A similar structure made from conventional materials, those with a positive index of refraction, would disperse the waves. But until recently, these structures have been purely theoretical because substances with both a negative permittivity and negative permeability, material properties necessary for a negative index of refraction, do not naturally exist, Recent developments have produced a structure composed of an array of thin wires and split ring resonators that shows a negative index of refraction. area smaller than a square wavelength. How small the area is can be determined by how perfectly the lens is polished and how pure the substance is that composes the lens. These lenses must also be curved for focusing to occur. The focal length is determined by the curvature of the lens and the material. On the other hand, a flat structure made from LHM would focus light because of the effect of a negative index of refraction in Snell s law. The focal length could also be varied by simply adjusting the distance of the lens from the source of radiation. This could create many devices that are adjustable to different situations in fields such as biomedical imaging and communication. the software package XFDTD which solves Maxwell s equations in the frequency domain as well as the time domain. The program used Drude models of materials to simulate the effect of negative permittivity and negative permeability. Because of this, a LHM can be simulated as a solid block of material instead of an array of wires and split ring resonators. After a flat lens is formed, I am to examine the focusing effect of the lens and determine if a higher resolution flat lens can be developed. Traditional lenses made from conventional materials cannot focus an EM wave onto an My goal was to model LHMs and create a flat lens from them. This was to be done using

  10. An Optical See-Through Head Mounted Display with Addressable Focal Planes

    E-print Network

    Hua, Hong

    FocalPlane.wmv) of a virtual torus rendered by the see-through HMD moving along the z-axis in the augmented space. The three. In this paper, we present a see-through HMD with addressable focal planes utilizing a novel active optical to address the focal distance of the HMD from infinity to the near point of the eye. A monocular prototype

  11. [The influence of camera-to-object distance and focal length on the representation of faces].

    PubMed

    Verhoff, Marcel A; Witzel, Carsten; Ramsthaler, Frank; Kreutz, Kerstin

    2007-01-01

    When one thinks of the so-called barrel or wide-angle distortion, grotesquely warped faces may come to mind. For less extreme cases with primarily inconspicuous facial proportions, the question, however, still arises whether there may be a resulting impact on the identification of faces. In the first experiment, 3 test persons were photographed at a fixed camera-to-object distance of 2 m. In the second experiment, 18 test persons were each photographed at a distance of 0.5 m and 2.0 m. For both experiments photographs were taken from a fixed angle of view in alignment with the Frankfurt Plane. An isolated effect of the focal length on facial proportions could not be demonstrated. On the other hand, changes in the camera-to-object distance clearly influenced facial proportions and shape. A standardized camera-to-object distance for passport photos, as well as reconstruction of the camera-to-object distance from crime scene photos and the use of this same distance in taking photographs for comparison of suspects are called for. A proposal to refer to wide-angle distortion as the nearness effect is put forward. PMID:17879705

  12. FOCAL PLANE WAVEFRONT SENSING USING RESIDUAL ADAPTIVE OPTICS SPECKLES

    SciTech Connect

    Codona, Johanan L.; Kenworthy, Matthew, E-mail: jlcodona@gmail.com [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)

    2013-04-20

    Optical imperfections, misalignments, aberrations, and even dust can significantly limit sensitivity in high-contrast imaging systems such as coronagraphs. An upstream deformable mirror (DM) in the pupil can be used to correct or compensate for these flaws, either to enhance the Strehl ratio or suppress the residual coronagraphic halo. Measurement of the phase and amplitude of the starlight halo at the science camera is essential for determining the DM shape that compensates for any non-common-path (NCP) wavefront errors. Using DM displacement ripples to create a series of probe and anti-halo speckles in the focal plane has been proposed for space-based coronagraphs and successfully demonstrated in the lab. We present the theory and first on-sky demonstration of a technique to measure the complex halo using the rapidly changing residual atmospheric speckles at the 6.5 m MMT telescope using the Clio mid-IR camera. The AO system's wavefront sensor measurements are used to estimate the residual wavefront, allowing us to approximately compute the rapidly evolving phase and amplitude of speckle halo. When combined with relatively short, synchronized science camera images, the complex speckle estimates can be used to interferometrically analyze the images, leading to an estimate of the static diffraction halo with NCP effects included. In an operational system, this information could be collected continuously and used to iteratively correct quasi-static NCP errors or suppress imperfect coronagraphic halos.

  13. Optical Arc-Length Sensor For TIG Welding

    NASA Technical Reports Server (NTRS)

    Smith, Matthew A.

    1990-01-01

    Proposed subsystem of tungsten/inert-gas (TIG) welding system measures length of welding arc optically. Viewed by video camera, in one of three alternative optical configurations. Length of arc measured instead of inferred from voltage.

  14. Intensity distribution near focal point of high aperture optical system formed by partly polarized light

    Microsoft Academic Search

    Volodymyr Borovytsky; Viktoriia Chorna

    2009-01-01

    The paper presents the mathematical technique for calculation of three dimensional intensity distribution near a focal point of a high aperture optical system in case of quasi monochromatic partly polarized light. This technique is extension of the vector diffraction theory for high aperture optical systems. It is based on Huygens-Fresnel principle: spherical wave at an exit pupil is considered as

  15. Very long gauge length fiber optic seismic event detectors

    Microsoft Academic Search

    William B. Spillman; Dryver R. Huston; Junru Wu

    1998-01-01

    Integrating fiber optic sensors offer the potential to monitor large spatial extends due to their geometric flexibility. To date, this potential has not been widely exploited. By increasing the length of an integrating fiber optic sensor, its gain and\\/or gauge length can be increased. In addition, by configuring the sensor to a spatial distribution of some parameter field of interest,

  16. EVLA MEMO #10 PREDICTED OPTICAL FIBER LENGTH VARIATIONS

    E-print Network

    Groppi, Christopher

    EVLA MEMO #10 PREDICTED OPTICAL FIBER LENGTH VARIATIONS DUE TO TEMPERATURE CHANGES TERRY COTTER; Table I: Fiber Segments Segment Max expected path length 1. Control building segment ( Antenna back end mode fiber. IV. Analysis Analysis is being done to determine the over all length variation due

  17. Nonlinear focal region formed in transient thermal self-focusing of laser radiation in optical glass

    Microsoft Academic Search

    V. V. Radchenko; Gennadii M. Fedorov

    1977-01-01

    An experimental investigation was made of transient thermal self-focusing of free-oscillation neodymium laser radiation in optical glass. The position of a nonlinear focal region was determined in the case of self-focusing of converging, parallel, and diverging laser radiation beams. A comparison was made of the results obtained with theoretical predictions.

  18. Focal characteristics of spheroidal geodesic lenses for integrated optical processing

    Microsoft Academic Search

    DAVID W. VAHEY; V. Wood

    1977-01-01

    Aspheric shaping of geodesic lenses in optical waveguides is suggested as a means for correcting spherical aberrations. The technique is complementary to the method of Spiller and Harper, in which geodesic lens aberrations are reduced by thickening the waveguiding layer in the lens region. The properties of a family of oblate-spheroidal lenses with no third-order spherical aberrations are described theoretically.

  19. All-optical controlling of the focal intensity of a liquid crystal polymer microlens array.

    PubMed

    Huang, San-Yi; Tung, Tung-Chen; Jau, Hung-Chang; Liu, Jui-Hsiang; Fuh, Andy Ying-Guey

    2011-10-20

    The current work demonstrates a liquid crystalline polymer microlens array (LCP MLA) with an all-optically tunable and multistable focal intensity through photochemical phase transition. The operational mechanism of the optical tuning is associated with the photoisomerization effect. The proposed LCP MLA device has a focusing unit based on a birefringence LCP and a tuning unit with a light responsive material to control the polarization state of the incident probe beam. The optically variable refractive indices of LCP enable a positive or negative MLA that can control the polarization of incident light to be realized. PMID:22015416

  20. Measurement of Trap Length for an Optical Trap

    NASA Technical Reports Server (NTRS)

    Wrbanek, Susan Y.

    2009-01-01

    The trap length along the beam axis for an optical trap formed with an upright, oil-immersion microscope was measured. The goals for this effort were twofold. It was deemed useful to understand the depth to which an optical trap can reach for purposes of developing a tool to assist in the fabrication of miniature devices. Additionally, it was desired to know whether the measured trap length favored one or the other of two competing theories to model an optical trap. The approach was to trap a microsphere of known size and mass and raise it from its initial trap position. The microsphere was then dropped by blocking the laser beam for a pre-determined amount of time. Dropping the microsphere in a free-fall mode from various heights relative to the coverslip provides an estimate of how the trapping length changes with depth in water in a sample chamber on a microscope slide. While it was not possible to measure the trap length with sufficient precision to support any particular theory of optical trap formation, it was possible to find regions where the presence of physical boundaries influenced optical traps, and determine that the trap length, for the apparatus studied, is between 6 and 7 m. These results allow more precise control using optical micromanipulation to assemble miniature devices by providing information about the distance over which an optical trap is effective.

  1. Dynamic optical properties in graphene: Length versus velocity gauge

    SciTech Connect

    Dong, H. M.; Han, K., E-mail: han6409@263.net [Department of Physics, China University of Mining and Technology, Xuzhou 221116 (China); Xu, W. [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Department of Physics, Yunnan University, Kunming 650091 (China)

    2014-02-14

    The dynamic optical properties of graphene are theoretically investigated in both length gauge and velocity gauge in the presence of ultrafast optical radiation field. The two gauges present different results of dynamic photo-induced carriers and optical conductance due to distinct dependencies on electric field and non-resonant optical absorption, while the two gauges give identical results in the steady state time. It shows that the choice of gauge affects evidently the dynamic optical properties of graphene. The velocity gauge represents an outcome of a real physical experiment.

  2. Ultra-low-loss tapered optical fibers with minimal lengths

    E-print Network

    Nagai, Ryutaro

    2014-01-01

    We design and fabricate ultra-low-loss tapered optical fibers (TOFs) with minimal lengths. We first optimize variations of the torch scan length using the flame-brush method for fabricating TOFs with taper angles that satisfy the adiabaticity criteria. We accordingly fabricate TOFs with optimal shapes and compare their transmission to TOFs with a constant taper angle and TOFs with an exponential shape. The highest transmission measured for TOFs with an optimal shape is in excess of 99.7 % with a total TOF length of only 23 mm, whereas TOFs with a constant taper angle of 2 mrad reach 99.6 % transmission for a 63 mm TOF length.

  3. Ultra-low-loss tapered optical fibers with minimal lengths

    E-print Network

    Ryutaro Nagai; Takao Aoki

    2014-11-09

    We design and fabricate ultra-low-loss tapered optical fibers (TOFs) with minimal lengths. We first optimize variations of the torch scan length using the flame-brush method for fabricating TOFs with taper angles that satisfy the adiabaticity criteria. We accordingly fabricate TOFs with optimal shapes and compare their transmission to TOFs with a constant taper angle and TOFs with an exponential shape. The highest transmission measured for TOFs with an optimal shape is in excess of 99.7 % with a total TOF length of only 23 mm, whereas TOFs with a constant taper angle of 2 mrad reach 99.6 % transmission for a 63 mm TOF length.

  4. Focal-Plane Imaging of Crossed Beams in Nonlinear Optics Experiments

    NASA Technical Reports Server (NTRS)

    Bivolaru, Daniel; Herring, G. C.

    2007-01-01

    An application of focal-plane imaging that can be used as a real time diagnostic of beam crossing in various optical techniques is reported. We discuss two specific versions and demonstrate the capability of maximizing system performance with an example in a combined dual-pump coherent anti-Stokes Raman scattering interferometric Rayleigh scattering experiment (CARS-IRS). We find that this imaging diagnostic significantly reduces beam alignment time and loss of CARS-IRS signals due to inadvertent misalignments.

  5. Design optimization and performance analysis of deformed optical readout focal plane array

    NASA Astrophysics Data System (ADS)

    Fu, Jianyu; Shang, Haiping; Shi, Haitao; Li, Zhigang; Yi, Ou; Chen, Dapeng; Zhang, Qingchuan

    2015-06-01

    An optical readout focal plane array (FPA) usually has a bent cantilever due to the micro-machining techniques. This bent morphology has a strong negative impact on optical sensitivity, which is a key factor that affects the imaging performance. In this study, an optical readout FPA with a stiffener-supported pixel is presented in order to reduce the deformation. The theoretical analysis has been developed to optimize the structure. Based on this, an FPA with a stiffener-supported pixel is fabricated. It is demonstrated that the curvature radius and optical sensitivity can increase by 5 times and 5.74 times respectively with respect to that without a stiffener. Better thermal imaging has been achieved.

  6. Test Bed For Control Of Optical-Path Lengths

    NASA Technical Reports Server (NTRS)

    O'Neal, Michael C.; Eldred, Daniel D.; Liu, Dankai; Redding, David C.

    1994-01-01

    Truss structure and ancillary equipment constitute test bed for experiments in methods of controlling lengths of optical paths under conditions of structural vibration and deformation. Accommodates both passive and active methods of control. Experimental control system reduces millimeter-level disturbances in optical path length to nanometers. Developed for control, alignment, and aiming of distributed optical systems on large flexible structures. Test bed includes tower 2.5 meters high with two horizontal arms extending at right angles from its top. Rigidly mounted on massive steel block providing measure of isolation from ground vibrations. Optical motion-compensation system similar to one described previously in NASA Tech Briefs enclosed in flexure-mounted frame, called "trolley," at end of longer horizontal arm.

  7. Measurement of the Length of an Optical Trap

    NASA Technical Reports Server (NTRS)

    Wrbanek, Susan Y.

    2010-01-01

    NASA Glenn has been involved in developing optical trapping and optical micromanipulation techniques in order to develop a tool that can be used to probe, characterize, and assemble nano and microscale materials to create microscale sensors for harsh flight environments. In order to be able to assemble a sensor or probe candidate sensor material, it is useful to know how far an optical trap can reach; that is, the distance beyond/below the stable trapping point through which an object will be drawn into the optical trap. Typically, to measure the distance over which an optical trap would influence matter in a horizontal (perpendicular to beam propagation) direction, it was common to hold an object in one optical trap, place a second optical trap a known distance away, turn off the first optical trap, and note if the object was moved into the second trap when it was turned on. The disadvantage of this technique is that it only gives information of trap influence distance in horizontal (x y) directions. No information about the distance of the influence of the trap is gained in the direction of propagation of the beam (the z direction). A method was developed to use a time-of-flight technique to determine the length along the propagation direction of an optical trap beam over which an object may be drawn into the optical trap. Test objects (polystyrene microspheres) were held in an optical trap in a water-filled sample chamber and raised to a pre-determined position near the top of the sample chamber. Next, the test objects were released by blocking the optical trap beam. The test objects were allowed to fall through the water for predetermined periods of time, at the end of which the trapping beam was unblocked. It was noted whether or not the test object returned to the optical trap or continued to fall. This determination of the length of an optical trap's influence by this manner assumes that the test object falls through the water in the sample chamber at terminal velocity for the duration of its fall, so that the distance of trap influence can be computed simply by: d = VTt, where d is the trap length (or distance of trap reach), VT is the terminal velocity of the test object, and t is the time interval over which the object is allowed to fall.

  8. Measurement and compensation of laser-induced wavefront deformations and focal shifts in near IR optics.

    PubMed

    Stubenvoll, Martin; Schäfer, Bernd; Mann, Klaus

    2014-10-20

    We demonstrate the feasibility of passive compensation of the thermal lens effect in fused silica optics, placing suitable optical materials with negative dn/dT in the beam path of a high power near IR fiber laser. Following a brief overview of the involved mechanisms, photo-thermal absorption measurements with a Hartmann-Shack sensor are described, from which coefficients for surface/coating and bulk absorption in various materials are determined. Based on comprehensive knowledge of the 2D wavefront deformations resulting from absorption, passive compensation of thermally induced aberrations in complex optical systems is possible, as illustrated for an F-Theta objective. By means of caustic measurements during high-power operation we are able to demonstrate a 60% reduction of the focal shift in F-Theta lenses through passive compensation. PMID:25401572

  9. Thermoacoustic optical path length stabilization in a single-mode optical fiber.

    PubMed

    Lewoczko-Adamczyk, Wojciech; Schiemangk, Max; Müller, Holger; Peters, Achim

    2009-02-01

    We present a simple technique to actively stabilize the optical path length in an optical fiber. A part of the fiber is coated with a thin, electrically conductive layer, which acts as a heater. The optical path length is thus modified by temperature-dependent changes in the refractive index and the mechanical length of the fiber. For the first time, we measure the dynamic response of the optical path length to the periodic changes of temperature and find it to be in agreement with our former theoretical prediction. The fiber's response to the temperature changes is determined by the speed of sound in quartz rather than by slow thermal diffusion. Making use of this fact, we succeeded in actively stabilizing the optical path length with a closed-loop bandwidth of 3.8 kHz. PMID:19183596

  10. Focal Activation of Cells by Plasmon Resonance Assisted Optical Injection of Signaling Molecules

    PubMed Central

    2015-01-01

    Experimental methods for single cell intracellular delivery are essential for probing cell signaling dynamics within complex cellular networks, such as those making up the tumor microenvironment. Here, we show a quantitative and general method of interrogation of signaling pathways. We applied highly focused near-infrared laser light to optically inject gold-coated liposomes encapsulating bioactive molecules into single cells for focal activation of cell signaling. For this demonstration, we encapsulated either inositol trisphosphate (IP3), an endogenous cell signaling second messenger, or adenophostin A (AdA), a potent analogue of IP, within 100 nm gold-coated liposomes, and injected these gold-coated liposomes and their contents into the cytosol of single ovarian carcinoma cells to initiate calcium (Ca2+) release from intracellular stores. Upon optical injection of IP3 or AdA at doses above the activation threshold, we observed increases in cytosolic Ca2+ concentration within the injected cell initiating the propagation of a Ca2+ wave throughout nearby cells. As confirmed by octanol-induced inhibition, the intercellular Ca2+ wave traveled via gap junctions. Optical injection of gold-coated liposomes represents a quantitative method of focal activation of signaling cascades of broad interest in biomedical research. PMID:24877558

  11. Free space optical communication performance analysis with focal plane based wavefront measurement

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Shi, Wenxiao; Wang, Bin; Yao, Kainan; Lv, Yaowen; Wang, Jihong

    2013-11-01

    In order to decrease the Bit Error Rate (BER) and increase coupling efficiency of free space optical (FSO) communication system, we compute and compensate the wavefront aberrations of the laser signal with the wavefront measurement method based on the focal plane proposed in this paper. The aberrations of laser signal are calculated based on the two images which are respectively generated from focal plane (PF) channel and the defocused plane (DF) channel. Assuming the On-Off Keying (OOK) modulation is used under the condition of weak turbulence, the fundamental of wavefront measurement method based on focal plane is introduced. By numerical simulation, we analyze the variation trend of coupling efficiency and BER, using the method we proposed to measure and compensate the wavefront aberrations for the FSO communication system. The experiment results show that the wavefront measurement error can reach nearly 0.004 wavelengths, the average coupling efficiency increases from 10.32% to 63.82%, and the average BER of FSO communication system decreases from 10-5 to 10-13.

  12. Studying focal ratio degradation of optical fibers for Subaru Prime Focus Spectrograph

    E-print Network

    Santos, Jesulino Bispo dos; Gunn, James; de Oliveira, Ligia Souza; de Arruda, Marcio Vital; Castilho, Bruno; Gneiding, Clemens Darvin; Ribeiro, Flavio Felipe; Murray, Graham; Reiley, Daniel J; Junior, Laerte Sodré; de Oliveira, Claudia Mendes

    2014-01-01

    Focal Ration Degradation (FRD) is a change in light angular distribution caused by fiber optics. FRD is important to fiber-fed, spectroscopic astronomical systems because it can cause loss of signal, degradation in spectral resolution, or increased complexity in spectrograph design. Laborat\\'orio Nacional de Astrof\\'isica (LNA) has developed a system that can accurately and precisely measures FRD, using an absolute method that can also measure fiber throughput. This paper describes the metrology system and shows measurements of Polymicro fiber FBP129168190, FBP127165190 and Fujikura fiber 128170190. Although the FRD of the two fibers are low and similar to one another, it is very important to know the exact characteristics of these fibers since both will be used in the construction of FOCCoS (Fiber Optical Cable and Connectors System) for PFS (Prime Focus Spectrograph) to be installed at the Subaru telescope.

  13. A superconducting focal plane array for ultraviolet, optical, and near-infrared astrophysics

    E-print Network

    Mazin, Benjamin A; Meeker, Seth R; O'Brien, Kieran; McHugh, Sean; Langman, Eric

    2011-01-01

    Microwave Kinetic Inductance Detectors, or MKIDs, have proven to be a powerful cryogenic detector technology due to their sensitivity and the ease with which they can be multiplexed into large arrays. A MKID is an energy sensor based on a photon-variable superconducting inductance in a lithographed microresonator, and is capable of functioning as a photon detector across the electromagnetic spectrum as well as a particle detector. Here we describe the first successful effort to create a photon-counting, energy-resolving ultraviolet, optical, and near infrared MKID focal plane array. These new Optical Lumped Element (OLE) MKID arrays have significant advantages over semiconductor detectors like charge coupled devices (CCDs). They can count individual photons with essentially no false counts and determine the energy and arrival time of every photon with good quantum efficiency. Their physical pixel size and maximum count rate is well matched with large telescopes. These capabilities enable powerful new astrophy...

  14. Studying focal ratio degradation of optical fibers for Subaru's Prime Focus Spectrograph

    NASA Astrophysics Data System (ADS)

    dos Santos, Jesulino Bispo; de Oliveira, Antonio Cesar; Gunn, James; de Oliveira, Ligia Souza; Vital de Arruda, Marcio; Castilho, Bruno; Gneiding, Clemens Darvin; Ribeiro, Flavio Felipe; Murray, Graham; Reiley, Daniel J.; Sodré Junior, Laerte; de Oliveira, Claudia Mendes

    2014-07-01

    Focal Ration Degradation (FRD) is a change in light's angular distribution caused by fiber optics. FRD is important to fiber-fed, spectroscopic astronomical systems because it can cause loss of signal, degradation in spectral resolution, or increased complexity in spectrograph design. Laboratório Nacional de Astrofísica (LNA) has developed a system that can accurately and precisely measures FRD, using an absolute method that can also measure fiber throughput. This paper describes the metrology system and shows measurements of Polymicro's fiber FBP129168190, FBP127165190 and Fujikura fiber 128170190. Although the FRD of the two fibers are low and similar to one another, it is very important to know the exact characteristics of these fibers since both will be used in the construction of FOCCoS (Fiber Optical Cable and Connectors System) for PFS (Prime Focus Spectrograph) to be installed at the Subaru telescope.

  15. Optical microangiography reveals collateral blood perfusion dynamics in mouse cerebral cortex after focal stroke

    NASA Astrophysics Data System (ADS)

    Baran, Utku; Li, Yuandong; Wang, Ruikang K.

    2015-03-01

    Arteriolo-arteriolar anastomosis's role in regulating blood perfusion through penetrating arterioles during stroke is yet to be discovered. We apply ultra-high sensitive optical microangiography (UHS-OMAG) and Doppler optical microangiography (DOMAG) techniques to evaluate vessel diameter and red blood cell velocity changes in large number of pial and penetrating arterioles in relation with arteriolo-arteriolar anastomosis (AAA) during and after focal stroke. Thanks to the high sensitivity of UHS-OMAG, we were able to image pial microvasculature up to capillary level through a cranial window (9 mm2), and DOMAG provided clear image of penetrating arterioles up to 500?m depth. Results showed that penetrating arterioles close to a strong AAA connection dilate whereas penetrating arterioles constrict significantly in weaker AAA regions. These results suggest that AAA plays a major role in active regulation of the pial arterioles, and weaker AAA connections lead to poor blood perfusion to penumbra through penetrating arterioles.

  16. Laser Scanning Focal Length Variability is a Measure of Damage in Rat Lens in Model Astronaut Cataracts Treated with Vitamin E (Ve) or R-?-Lipoic Acid (RLA)

    Microsoft Academic Search

    V. Bantseev; K. Herbert; J. G. Sivak; J. R. Trevithick

    \\u000a Lenses of rats, selected by clarity and\\/or low protein leakage during preincubation, were incubated in medium 199 (M199).\\u000a 60Co-?-irradiation simulated radiation encountered in space, although ?-irradiation causes less damage than cosmic rays. At\\u000a the termination of incubation, lenses were scanned by a Scanning Lens Monitor. Protein leakage was positively correlated with\\u000a variability in focal length (p <0.04). Irradiated lenses had

  17. Optics

    NSDL National Science Digital Library

    Wolfgang Christian

    This page allows users to simulate standard optic elements (lens, mirror, dielectrics, sources, apertures) and observe how light rays propagate through these elements. Element properties, such as position and focal length, can be adjusted using and a click and drag metaphor.

  18. Extended-length fiber optic carbon dioxide monitoring

    NASA Astrophysics Data System (ADS)

    Delgado-Alonso, Jesus; Lieberman, Robert A.

    2013-05-01

    This paper discusses the design and performance of fiber optic distributed intrinsic sensors for dissolved carbon dioxide, based on the use optical fibers fabricated so that their entire lengths are chemically sensitive. These fibers use a polymer-clad, silica-core structure where the cladding undergoes a large, reversible, change in optical absorbance in the presence of CO2. The local "cladding loss" induced by this change is thus a direct indication of the carbon dioxide concentration in any section of the fiber. To create these fibers, have developed a carbon dioxide-permeable polymer material that adheres well to glass, is physically robust, has a refractive index lower than fused silica, and acts as excellent hosts for a unique colorimetric indicator system that respond to CO2. We have used this proprietary material to produce carbon-dioxide sensitive fibers up to 50 meters long, using commercial optical fiber fabrication techniques. The sensors have shown a measurement range of dissolved CO2 of 0 to 1,450 mg/l (0 to 100% CO2 saturation), limit of detection of 0.3 mg/l and precision of 1.0 mg/l in the 0 to 50 mg/l dissolved CO2 range, when a 5 meter-long sensor fiber segment is used. Maximum fiber length, minimum detectable concentration, and spatial resolution can be adjusted by adjusting indicator concentration and fiber design.

  19. Optical fiber length measurement by external phase modulation type optical heterodyne reflectometry

    SciTech Connect

    Kimura, T.; Sawada, I.; Sasaki, N.; Noda, K. (Dept. of Electrical Engineering, Tokyo Univ. of Agriculture and Technology, 24-16, Nakamachi 2-chome, Koganei-shi, Tokyo 184 (JP))

    1989-04-01

    A method for measuring optical fiber length is proposed and demonstrated experimentally with external phase modulation optical heterodyne reflectometry using a He-Ne laser as a light source. The system offers a simple length measuring method with satisfactory resolution. The reflected waves from fiber faults, if any, also can be detected by this method by observing two signals which occur at fault points and the fiber end.

  20. Interference model for back-focal-plane displacement detection in optical tweezers.

    PubMed

    Gittes, F; Schmidt, C F

    1998-01-01

    The lateral position of an optically trapped object in a microscope can be monitored with a quadrant photodiode to within nanometers or better by measurement of intensity shifts in the back focal plane of the lens that is collimating the outgoing laser light. This detection is largely independent of the position of the trap in the field of view. We provide a model for the essential mechanism of this type of detection, giving a simple, closed-form analytic solution with simplifying assumptions. We identify intensity shifts as first-order far-field interference between the outgoing laser beam and scattered light from the trapped particle, where the latter is phase advanced owing to the Gouy phase anomaly. This interference also reflects momentum transfer to the particle, giving the spring constant of the trap. Our response formula is compared with the results of experiments. PMID:18084394

  1. Fiber optically coupled infrared focal plane array system for use in missile warning receiver applications

    NASA Astrophysics Data System (ADS)

    Daniels, Arnold; Liepmann, Till W.

    1999-07-01

    The location and installation of mid-infrared missile warning receiver sensors is limited by the mechanical constraints of the detector/dewar assembly and the associated cryogenic cooler assembly. The size, shape, and weight of these assemblies limit the installation alternatives, and prevent placing the missile warning receiver system in the optimum locations. Hence, their coverage and detection performance is limited. A micro-lens array coupled to a coherent fiber optic bundle and an infrared focal plane array were designed and experimentally implemented, to allow the mid-wave sensor and cryogenic devices to be located remotely from the receiver aperture. This eliminates the receiver aperture placement restrictions while easing the integration and maintenance of the sensor/dewar and cooler. Modulation transfer function and noise equivalent temperature difference measurements were performed to determine the performance of the imaging system.

  2. The focal plane adaptive optics test box of the Observatoire du Mont-Mégantic

    NASA Astrophysics Data System (ADS)

    Deschênes, William; Brousseau, Denis; Lavigne, Jean-Francois; Thibault, Simon; Véran, Jean-Pierre

    2014-08-01

    With the upcoming construction of Extremely Large Telescopes, several existing technologies are being pushed beyond their performance limit and it becomes essential to develop and evaluate new alternatives. The "Observatoire du Mont Mégantic" (OMM) hosts a telescope having a 1.6-meter diameter primary. The OMM telescope is known to be an excellent location to develop and test precursor instruments which are then upscaled to larger telescopes (ex. SPIOMM which led to SITELLE at the CFHT). We present a specifically designed focal plane box for the OMM which will allow to evaluate, directly on-sky, the performance of a number of next generation adaptive optics related technologies The system will able us to compare the performance of several new wavefront sensors in contrast with the current standard, the Shack-Hartman wavefront sensor.

  3. To construct a stable and tunable optical trap in the focal region of a high numerical aperture lens

    NASA Astrophysics Data System (ADS)

    Kandasamy, Gokulakrishnan; Ponnan, Suresh; Sivasubramonia Pillai, T. V.; Balasundaram, Rajesh K.

    2014-05-01

    Based on the diffraction theory, the focusing properties of a radially polarized quadratic Bessel-Gaussian beam (QBG) with on-axis radial phase variance wavefront are investigated theoretically in the focal region of a high numerical aperture (NA) objective lens. The phase wavefront C and pupil beam parameter ? of QBG are the functions of the radial coordinate. The detailed numerical calculation of the focusing property of a QBG beam is presented. The numerical calculation shows that the beam parameter ? and phase parameter C have greater effect on the total electric field intensity distribution. It is observed that under the condition of different ?, evolution principle of focal pattern differs very remarkably on increasing C. Also, some different focal shapes may appear, including rhombic shape, quadrangular shape, two-spherical crust focus shape, two-peak shape, one dark hollow focus, two dark hollow focuses pattern, and triangle dark hollow focus, which find wide optical applications such as optical trapping and nanopatterning.

  4. VLTI focal instrument AMBER: results of laboratory commissioning of the warm optics

    NASA Astrophysics Data System (ADS)

    Robbe-Dubois, Sylvie; Bresson, Yves; Antonelli, Pierre; Bonhomme, S.; Lagarde, Stephane; Martinot-Lagarde, Gregoire; Petrov, Romain G.; Puget, Pascal; Reynaud, Francois; Roussel, Andre; Rousselet-Perraut, Karine; Tassot, Daniel; Vannier, Martin

    2003-02-01

    AMBER, Astronomical Multi BEam combineR, is the near-infrared focal instrument dedicated to the VLTI. It is designed to combine three of the VLTI Telescopes and to work simultaneously in the J, H and K spectral bands (1.1 to 2.4 ?m). The instrumental concept and its opto-mechanic specifications were defined in order to reach the ambitious scientific requirements to satisfy the core astrophysical programs. The project passed the Final Design Review in May 2001, phase which marks the acceptation of the instrument final design and the beginning of the construction and tests. After this phase, optics and mechanical systems have been receptioned since February 2002, for the laboratory tests and alignments. The cooled spectrograph and its cryostat is assembled at the Osservatorio di Arcetri in Firenze, Italy and the cooled detector at the Max-Planck-Institut für Radioastronomie in Bonn, Deutschland. The warm optics, including spatial filter in K and artificial sources injection system, have been pre-aligned at the Observatoire de la Côte d'Azur in Nice, France to validate most of the alignment procedure, the required element accuracies and the associated degrees of freedom. The whole instrument is then currently fully assembled and optimized at the Laboratoire d'Astrophysique de l'Observatoire de Grenoble, France. Its sensitivity and final performance will be evaluated in order to reach the Preliminary Acceptance in Europe, scheduled beginning 2003. This paper gives the results of the warm optics laboratory commissioning.

  5. Optical scattering lengths in large liquid-scintillator neutrino detectors.

    PubMed

    Wurm, M; von Feilitzsch, F; Göger-Neff, M; Hofmann, M; Lachenmaier, T; Lewke, T; Marrodán Undagoitia, T; Meindl, Q; Möllenberg, R; Oberauer, L; Potzel, W; Tippmann, M; Todor, S; Traunsteiner, C; Winter, J

    2010-05-01

    For liquid-scintillator neutrino detectors of kiloton scale, the transparency of the organic solvent is of central importance. The present paper reports on laboratory measurements of the optical scattering lengths of the organic solvents phenylxylylethane, linear alkylbenzene (LAB), and dodecane, which are under discussion for next-generation experiments such as SNO+ (Sudbury Neutrino Observatory), HanoHano, or LENA (Low Energy Neutrino Astronomy). Results comprise the wavelength range of 415-440 nm. The contributions from Rayleigh and Mie scattering as well as from absorption/re-emission processes are discussed. Based on the present results, LAB seems to be the preferred solvent for a large-volume detector. PMID:20515130

  6. Laser Metrology for an Optical-Path-Length Modulator

    NASA Technical Reports Server (NTRS)

    Gursel, Yekta

    2005-01-01

    Laser gauges have been developed to satisfy requirements specific to monitoring the amplitude of the motion of an optical-path-length modulator that is part of an astronomical interferometer. The modulator includes a corner-cube retroreflector driven by an electromagnetic actuator. During operation of the astronomical interferometer, the electromagnet is excited to produce linear reciprocating motion of the corner-cube retroreflector at an amplitude of 2 to 4 mm at a frequency of 250, 750, or 1,250 Hz. Attached to the corner-cube retroreflector is a small pick-off mirror. To suppress vibrations, a counterweight having a mass equal to that of the corner-cube retroreflector and pick-off mirror is mounted on another electromagnetic actuator that is excited in opposite phase. Each gauge is required to measure the amplitude of the motion of the pick-off mirror, assuming that the motions of the pick-off mirror and the corner-cube retroreflector are identical, so as to measure the amplitude of motion of the corner- cube retroreflector to within an error of the order of picometers at each excitation frequency. Each gauge is a polarization-insensitive heterodyne interferometer that includes matched collimators, beam separators, and photodiodes (see figure). The light needed for operation of the gauge comprises two pairs of laser beams, the beams in each pair being separated by a beat frequency of 80 kHz. The laser beams are generated by an apparatus, denoted the heterodyne plate, that includes stabilized helium-neon lasers, acousto-optical modulators, and associated optical and electronic subsystems. The laser beams are coupled from the heterodyne plate to the collimators via optical fibers.

  7. Determination of charge-carrier diffusion length in the photosensing layer of HgCdTe n-on-p photovoltaic infrared focal plane array detectors

    SciTech Connect

    Vishnyakov, A. V.; Stuchinsky, V. A., E-mail: stuchin@isp.nsc.ru; Brunev, D. V.; Zverev, A. V.; Dvoretsky, S. A. [Institute of Semiconductor Physics, Russian Academy of Science, Siberian Division, 13, Acad. Lavrent'ev Avenue, Novosibirsk 630090 (Russian Federation)

    2014-03-03

    In the present paper, we propose a method for evaluating the bulk diffusion length of minority charge carriers in the photosensing layer of photovoltaic focal plane array (FPA) photodetectors. The method is based on scanning a strip-shaped illumination spot with one of the detector diodes at a low level of photocurrents j{sub ph} being registered; such scanning provides data for subsequent analysis of measured spot-scan profiles within a simple diffusion model. The asymptotic behavior of the effective (at j{sub ph}???0) charge-carrier diffusion length l{sub d} {sub eff} as a function of j{sub ph} for j{sub ph} ? 0 inferred from our experimental data proved to be consistent with the behavior of l{sub d} {sub eff} vs j{sub ph} as predicted by the model, while the obtained values of the bulk diffusion length of minority carriers (electrons) in the p-HgCdTe film of investigated HgCdTe n-on-p FPA photodetectors were found to be in a good agreement with the previously reported carrier diffusion-length values for HgCdTe.

  8. Active optical zoom system

    DOEpatents

    Wick, David V.

    2005-12-20

    An active optical zoom system changes the magnification (or effective focal length) of an optical imaging system by utilizing two or more active optics in a conventional optical system. The system can create relatively large changes in system magnification with very small changes in the focal lengths of individual active elements by leveraging the optical power of the conventional optical elements (e.g., passive lenses and mirrors) surrounding the active optics. The active optics serve primarily as variable focal-length lenses or mirrors, although adding other aberrations enables increased utility. The active optics can either be LC SLMs, used in a transmissive optical zoom system, or DMs, used in a reflective optical zoom system. By appropriately designing the optical system, the variable focal-length lenses or mirrors can provide the flexibility necessary to change the overall system focal length (i.e., effective focal length), and therefore magnification, that is normally accomplished with mechanical motion in conventional zoom lenses. The active optics can provide additional flexibility by allowing magnification to occur anywhere within the FOV of the system, not just on-axis as in a conventional system.

  9. Novel volumetric 3D display based on point light source optical reconstruction using multi focal lens array

    NASA Astrophysics Data System (ADS)

    Lee, Jin su; Lee, Mu young; Kim, Jun oh; Kim, Cheol joong; Won, Yong Hyub

    2015-03-01

    Generally, volumetric 3D display panel produce volume-filling three dimensional images. This paper discusses a volumetric 3D display based on periodical point light sources(PLSs) construction using a multi focal lens array(MFLA). The voxel of discrete 3D images is formed in the air via construction of point light source emitted by multi focal lens array. This system consists of a parallel beam, a spatial light modulator(SLM), a lens array, and a polarizing filter. The multi focal lens array is made with UV adhesive polymer droplet control using a dispersing machine. The MFLA consists of 20x20 circular lens array. Each lens aperture of the MFLA shows 300um on average. The polarizing filter is placed after the SLM and the MFLA to set in phase mostly mode. By the point spread function, the PLSs of the system are located by the focal length of each lens of the MFLA. It can also provide the moving parallax and relatively high resolution. However it has a limit of viewing angle and crosstalk by a property of each lens. In our experiment, we present the letter `C', `O', `DE' and ball's surface with the different depth location. It could be seen clearly that when CCD camera is moved to its position following as transverse axis of the display system. From our result, we expect that varifocal lens like EWOD and LC-lens can be applied for real time volumetric 3D display system.

  10. Adaptive optical zoom sensor.

    SciTech Connect

    Sweatt, William C.; Bagwell, Brett E.; Wick, David Victor

    2005-11-01

    In order to optically vary the magnification of an imaging system, continuous mechanical zoom lenses require multiple optical elements and use fine mechanical motion to precisely adjust the separations between individual or groups of lenses. By incorporating active elements into the optical design, we have designed and demonstrated imaging systems that are capable of variable optical magnification with no macroscopic moving parts. Changing the effective focal length and magnification of an imaging system can be accomplished by adeptly positioning two or more active optics in the optical design and appropriately adjusting the optical power of those elements. In this application, the active optics (e.g. liquid crystal spatial light modulators or deformable mirrors) serve as variable focal-length lenses. Unfortunately, the range over which currently available devices can operate (i.e. their dynamic range) is relatively small. Therefore, the key to this concept is to create large changes in the effective focal length of the system with very small changes in the focal lengths of individual elements by leveraging the optical power of conventional optical elements surrounding the active optics. By appropriately designing the optical system, these variable focal-length lenses can provide the flexibility necessary to change the overall system focal length, and therefore magnification, that is normally accomplished with mechanical motion in conventional zoom lenses.

  11. Biometric measurement of the mouse eye using optical coherence tomography with focal plane advancement

    Microsoft Academic Search

    Xiangtian Zhou; Jing Xie; Meixiao Shen; Jianhua Wang; Liqin Jiang; Jia Qu; Fan Lu

    2008-01-01

    Purpose: To demonstrate that high-resolution biometry is possible in mouse eyes in vivo, using real-time OCT with focal plane advancement by a stepper motor.Methods: OCT images of eyes were taken from nine 29-day-old C57BL\\/6 mice(18 eyes) on two consecutive days. A custom-built real-time OCT instrument with a stepper motor was used to advance the focal plane from the corneal apex

  12. Automated optical testing of LWIR objective lenses using focal plane array sensors

    NASA Astrophysics Data System (ADS)

    Winters, Daniel; Erichsen, Patrik; Domagalski, Christian; Peter, Frank; Heinisch, Josef; Dumitrescu, Eugen

    2012-10-01

    The image quality of today's state-of-the-art IR objective lenses is constantly improving while at the same time the market for thermography and vision grows strongly. Because of increasing demands on the quality of IR optics and increasing production volumes, the standards for image quality testing increase and tests need to be performed in shorter time. Most high-precision MTF testing equipment for the IR spectral bands in use today relies on the scanning slit method that scans a 1D detector over a pattern in the image generated by the lens under test, followed by image analysis to extract performance parameters. The disadvantages of this approach are that it is relatively slow, it requires highly trained operators for aligning the sample and the number of parameters that can be extracted is limited. In this paper we present lessons learned from the R and D process on using focal plane array (FPA) sensors for testing of long-wave IR (LWIR, 8-12 m) optics. Factors that need to be taken into account when switching from scanning slit to FPAs are e.g.: the thermal background from the environment, the low scene contrast in the LWIR, the need for advanced image processing algorithms to pre-process camera images for analysis and camera artifacts. Finally, we discuss 2 measurement systems for LWIR lens characterization that we recently developed with different target applications: 1) A fully automated system suitable for production testing and metrology that uses uncooled microbolometer cameras to automatically measure MTF (on-axis and at several o-axis positions) and parameters like EFL, FFL, autofocus curves, image plane tilt, etc. for LWIR objectives with an EFL between 1 and 12mm. The measurement cycle time for one sample is typically between 6 and 8s. 2) A high-precision research-grade system using again an uncooled LWIR camera as detector, that is very simple to align and operate. A wide range of lens parameters (MTF, EFL, astigmatism, distortion, etc.) can be easily and accurately measured with this system.

  13. Seismic event monitoring using very long gauge length integrating fiber optic sensors

    Microsoft Academic Search

    William B. Spillman; Dryver R. Huston; Junru Wu

    2001-01-01

    Integrating fiber optic sensors offer the potential to monitor large spatial extents due to their geometry flexibility. To date, this potential has not been widely exploited. By increasing the length of an integrating fiber optic sensor, its gain and\\/or gauge length can be increased. In addition, by configuring the sensor to a spatial distribution of some parameter field of interest,

  14. Inverse scattering for frequency-scanned full-field optical coherence tomography

    E-print Network

    Bhargava, Rohit

    in the focal plane arrives. The reference and signal are superimposed and focused on a focal-plane array (such without compromising resolution away from the focal plane. © 2007 Optical Society of America OCIS codes a coherence length of the focal plane produce scat- tered fields that will interfere with the reference. By re

  15. Starch-based second-harmonic-generated collinear frequency-resolved optical gating pulse characterization at the focal plane of a high-numerical-aperture lens

    NASA Astrophysics Data System (ADS)

    Amat-Roldán, Ivan; Cormack, Iain G.; Loza-Alvarez, Pablo; Artigas, David

    2004-10-01

    We report the use of starch as an ideal nonlinear medium with which to perform collinear frequency-resolved optical gating measurements of ultrashort pulses at the focal plane of a high-numerical-aperture (NA) lens. We achieved these measurements by simply sandwiching starch granules (suspended in water) between two coverslips and placing them within the focal plane of a high-NA lens. The natural nonlinear characteristics of starch allow the correct phase matching of pulses at the focal plane of a high-NA lens at different wavelengths. This elegant arrangement overcomes all the complexity and problems that were previously associated with pulse characterization within a multiphoton microscope.

  16. Fabrication of long-focal-length plano-convex microlens array by combining the micro-milling and injection molding processes.

    PubMed

    Chen, Lei; Kirchberg, Stefan; Jiang, Bing-Yan; Xie, Lei; Jia, Yun-Long; Sun, Lei-Lei

    2014-11-01

    A uniform plano-convex spherical microlens array with a long focal length was fabricated by combining the micromilling and injection molding processes in this work. This paper presents a quantitative study of the injection molding process parameters on the uniformity of the height of the microlenses. The variation of the injection process parameters, i.e., barrel temperature, mold temperature, injection speed, and packing pressure, was found to have a significant effect on the uniformity of the height of the microlenses, especially the barrel temperature. The filling-to-packing switchover point is also critical to the uniformity of the height of the microlenses. The optimal uniformity was achieved when the polymer melts completely filled the mold cavity, or even a little excessively filled the cavity, during the filling stage. In addition, due to the filling resistance, the practical filling-to-packing switchover point can vary with the change of the filling processing conditions and lead to a non-negligible effect on the uniformity of the height of the microlenses. Furthermore, the effect of injection speed on the uniformity of the height of the microlenses was analyzed in detail. The results indicated that the effect of injection speed on the uniformity of the height of the microlenses is mainly attributed to the two functions of injection speed: transferring the filling-to-packing switchover point and affecting the distribution of residual flow stress in the polymer melt. PMID:25402902

  17. The implications of image scrambling and focal ratio degradation in fibre optics on the design of astronomical instrumentation

    NASA Astrophysics Data System (ADS)

    Clayton, C. A.

    1989-04-01

    The effects of image scrambling (IS) and focal ratio degradation (FRD) in fiber optic cables on the performance of astronomical instrumentation (such as the Manchester echelle spectrometers) were investigated, for both straight and bent fiber optic cables, on the basis of a literature review on IS and FRD and an experimental study. The investigation includes a comparison of the FRD performance of different 'astronomical' fibers, as a function of bend radius, and an examination of the effects of localized stress on FRD and fiber bending in short fibers; a determination of the effects of diffraction and bends on the amounts of FRD; and a determination of IS properties in short fibers. Results show that FRD is dominated by local stress, while microbends on the scale normally encountered in current instruments do not significantly affect FRD. It was also found that, in short (few cm) fibers, IS is incomplete and that the position of a source on a fiber determines the transmission efficiency.

  18. Fiber optic acoustic hydrophone with double Mach-Zehnder interferometers for optical path length compensation

    NASA Astrophysics Data System (ADS)

    Lim, T. K.; Zhou, Y.; Lin, Y.; Yip, Y. M.; Lam, Y. L.

    1999-01-01

    We report on the development of a fiber optic acoustic hydrophone which consists of a sensing Mach-Zehnder (MZ) interferometer and a compensating MZ interferometer for optical path length compensation. This double-interferometer configuration has the following advantages: the hydrophone is a true heterodyne device; a laser source with a short coherence length can be used; the sensing interferometer is completely passive; the compensating interferometer can be located near the signal processing electronics, far away from the sensing interferometer; a conventional modulation analyzer can be used to demodulate the optical phase shift, which greatly simplifies the demodulation electronics. The performance of the hydrophone is evaluated experimentally by immersing the sensing interferometer in a water tank to detect underwater acoustic signals generated by an acoustic wave projector. Experimental results show that over the frequency range of 5 to 20 kHz, the hydrophone has an almost flat response with an average normalized phase sensitivity of -322.3 dB re 1/?Pa and an average pressure sensitivity of -153.7 dB re rad/?Pa. These performance figures are better than those obtained from a commercial piezoelectric hydrophone. Furthermore, we have also demonstrated that with improved signal processing techniques, the normalized phase sensitivity of the hydrophone increases to -313 dB re 1/?Pa, and the pressure sensitivity increases to -136.9 dB re rad/?Pa. These results indicate that the present design offers equal or better performance in terms of sensitivity over its counterparts employing conventional Mach-Zehner configurations.

  19. Focal lengths and gravity waves

    E-print Network

    Doherty, Mary Jane

    1985-01-01

    Film is composed of tiny photographs which, when projected, sometimes look very much like people and things in the real world. Film, too, cannot be separated from its tools. Aesthetic criticism was, and still is, weighted ...

  20. New scintillators for fiber optics: system sensitivity and bandwidth as a function of fiber length

    SciTech Connect

    Lutz, S.; Franks, L.A.; Flournoy, J.M.; Lyons, P.B.

    1981-01-01

    Long-wavelength liquid scintillators have been developed for fiber-optic plasma-diagnostic experiments. Relative system sensitivity and bandwidth data as a function of fiber length for several scintillator systems will be presented.

  1. Effects of Conformational Disorder on the Conjugation Length and non Linear Optical Properties of Conjugated Polymers

    Microsoft Academic Search

    Sophia N. Yaliraki; Robert J. Silbey

    1997-01-01

    Conjugated polymers are of special interest due to the technological relevance of their nonlinear optical properties for photonic applications. The large non linear responses are in this case associated with the large one dimensional conjugation lengths of the delocalized p-electrons. Recent work has concentrated on the nature of conjugation lengths. We study the effect of conformational disorder on the electronic

  2. Characterization of a Test Site for the Measuring of the Focal Point of Reflective Optical Elements for Concentrator Photovoltaic

    E-print Network

    Frick, Manuel

    2014-01-01

    In order to achieve a large deployment of renewable energies, the electricity production costs have to be as low as possible. Many different technologies have been proposed to achieve the best efficiency to cost ratio. One of those is concentrating photovoltaics (CPV) which takes advantage of the high efficiency of multi-junction cells while limiting the costs by reducing the size of the cell and concentrating the direct irradiance with a cheaper optical element. Next to the widely used Fresnel lenses concave mirrors could be of interest as concentrator optic. As for the whole module those optics have to minimize losses and production costs at once. Measuring scattering and slope errors of the mirrors is of great importance to achieve an optimal design and production process. Therefore an optical test site doing so by observing the 2D irradiance distribution in the focal point has been built at the Fraunhofer ISE. The aim of this thesis is to characterize this test site. Therefore the behavior of the differen...

  3. Dysversion of the optic disc and axial length measurements in a presumed amblyopic population

    Microsoft Academic Search

    Philip Lempert; Lynn Porter

    1998-01-01

    Purpose: Our purpose was to evaluate anatomic variations of eyes presumed to be amblyopic. Method: Computer imaging and photography of the optic discs of 205 amblyopic subjects were performed and the axial lengths of 183 of the subjects were measured. The paired optic nerve images were evaluated for symmetry of disc contours and orientation of central blood vessels to detect

  4. Comparison of optical biometry and applanation ultrasound measurements of the axial length of the eye

    PubMed Central

    Nakhli, Fouad R.

    2014-01-01

    Purpose To investigate the relationship between optical biometry and applanation ultrasound measurement of the axial length of the eye. Materials and methods This prospective study enrolled 55 (68 eyes) consecutive patients scheduled for cataract surgery at Dhahran Eye Specialist Hospital (DESH). Every eye underwent two measurements each with an optical biometer and with applanation ultrasound. Only patients with cataract and no other ophthalmic pathology or disease were enrolled. Comparison, correlation and repeatability of axial length with both devices were analyzed. Agreement between devices was evaluated. A regression formula to convert measurements between devices was investigated. A p value less than 0.05 was statistically significant. Results There was strong repeatability (99.4%) and agreement (r = 0.987) between both devices (p < 0.001); the difference between devices was mainly in short eyes (p = 0.031). Conclusion Optical biometry and applanation ultrasound measurements of axial length correlate well. However, optical biometry is preferable in short eyes. PMID:25473345

  5. Optically controlled thermal management on the nanometer length scale

    NASA Astrophysics Data System (ADS)

    Garwe, F.; Bauerschäfer, U.; Csaki, A.; Steinbrück, A.; Ritter, K.; Bochmann, A.; Bergmann, J.; Weise, A.; Akimov, D.; Maubach, G.; König, K.; Hüttmann, G.; Paa, W.; Popp, J.; Fritzsche, W.

    2008-02-01

    The manipulation of polymers and biological molecules or the control of chemical reactions on a nanometer scale by means of laser pulses shows great promise for applications in modern nanotechnology, biotechnology, molecular medicine or chemistry. A controllable, parallel, highly efficient and very local heat conversion of the incident laser light into metal nanoparticles without ablation or fragmentation provides the means for a tool like a 'nanoreactor', a 'nanowelder', a 'nanocrystallizer' or a 'nanodesorber'. In this paper we explain theoretically and show experimentally the interaction of laser radiation with gold nanoparticles on a polymethylmethacrylate (PMMA) layer (one-photon excitation) by means of different laser pulse lengths, wavelengths and pulse repetition rates. To the best of our knowledge this is the first report showing the possibility of highly local (in a 40 nm range) regulated heat insertion into the nanoparticle and its surroundings without ablation of the gold nanoparticles. In an earlier paper we showed that near-infrared femtosecond irradiation can cut labeled DNA sequences in metaphase chromosomes below the diffraction-limited spot size. Now, we use gold as well as silver-enhanced gold nanoparticles on DNA (also within chromosomes) as energy coupling objects for femtosecond laser irradiation with single-and two-photon excitation. We show the results of highly localized destruction effects on DNA that occur only nearby the nanoparticles.

  6. Optical length change measurement via RF frequency shift analysis of incoherent light source based optoelectronic oscillator.

    PubMed

    Zou, Xihua; Li, Ming; Pan, Wei; Luo, Bin; Yan, Lianshan; Shao, Liyang

    2014-05-01

    Radio-frequency (RF) frequency shift of incoherent light source based optoelectronic oscillator (OEO) is employed to measure the optical length change. In the proposed OEO using an incoherent light source, the optical length under test is inserted in the optoelectronic hybrid loop. The frequency shift of RF oscillation modes at the output of the OEO reflects the optical length change, with the change being measured via frequency shift analysis. Two OEO configurations are theoretically designed and experimentally performed, while an amplified spontaneous emission (ASE) source serves as the incoherent light source. A linear relationship between the frequency shift and the optical length change has been confirmed for measurement, and a reconfigurable measurement sensitivity is available by selecting different oscillation modes. Moreover, the use of ASE greatly reduces the complexity and the cost for stabilization control on light source, while the derived results are consistent with that obtained in a laser source based OEO both in the measured optical length changes and the phase noise performance. A sensitivity of -28 KHz/cm, -480 KHz/cm or higher, and a resolution of nano-meter scale are obtained, which can be used to monitor the displacement, the changes in refractive index, temperature. PMID:24921811

  7. Extended Nijboer-Zernike representation of the vector field in the focal region of an aberrated high-aperture optical system

    Microsoft Academic Search

    Joseph J. M. Braat; Peter Dirksen; Augustus J. E. M. Janssen; Arthur S. van de Nes

    2003-01-01

    Taking the classical Ignatowsky\\/Richards and Wolf formulas as our starting point, we present expressions for the electric field components in the focal region in the case of a high-numerical-aperture optical system. The transmission function, the aberrations, and the spatially varying state of polarization of the wave exiting the optical system are represented in terms of a Zernike polynomial expansion over

  8. Influence of temperature on divergence angle of a focal telescope used in laser optical communication.

    PubMed

    Zheng, Guoxian; Zhou, Feng; Liu, Jianfeng; Li, Tuotuo; An, Ning; Zhang, Binglong

    2012-06-01

    Divergence angle of antenna is an important parameter in laser optical communication. It determines the power of the receiver terminal. In this paper, the influence of temperature on the divergence angle is discussed. Theoretical analysis and experiment results demonstrate that the relationship between the variance of temperature and of divergence angle is linear. PMID:22714349

  9. ccsd-00007728,version3-16Sep2005 Long-term stabilization of the length of an optical reference cavity

    E-print Network

    Boyer, Edmond

    ccsd-00007728,version3-16Sep2005 Long-term stabilization of the length of an optical reference degree of long-term length stabilisation of an optical reference cavity, its free- spectral range in frequency to be in resonance with the (N+1)th mode of the cavity. This shift is generated by an acousto-optical

  10. Remote acute demyelination after focal proton radiation therapy for optic nerve meningioma.

    PubMed

    Redjal, Navid; Agarwalla, Pankaj K; Dietrich, Jorg; Dinevski, Nikolaj; Stemmer-Rachamimov, Anat; Nahed, Brian V; Loeffler, Jay S

    2015-08-01

    We present a unique patient with delayed onset, acute demyelination that occurred distant to the effective field of radiation after proton beam radiotherapy for an optic nerve sheath meningioma. The use of stereotactic radiotherapy as an effective treatment modality for some brain tumors is increasing, given technological advances which allow for improved targeting precision. Proton beam radiotherapy improves the precision further by reducing unnecessary radiation to surrounding tissues. A 42-year-old woman was diagnosed with an optic nerve sheath meningioma after initially presenting with vision loss. After biopsy of the lesion to establish diagnosis, the patient underwent stereotactic proton beam radiotherapy to a small area localized to the tumor. Subsequently, the patient developed a large enhancing mass-like lesion with edema in a region outside of the effective radiation field in the ipsilateral frontal lobe. Given imaging features suggestive of possible primary malignant brain tumor, biopsy of this new lesion was performed and revealed an acute demyelinating process. This patient illustrates the importance of considering delayed onset acute demyelination in the differential diagnosis of enhancing lesions in patients previously treated with radiation. PMID:25937571

  11. Length-dependent optical properties of single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Simpson, J. R.; Fagan, J. A.; Bauer, B. J.; Hobbie, E. K.; Hight Walker, A. R.

    2008-03-01

    Length proves to be an important physical characteristic of single-walled carbon nanotubes (SWCNTs) strongly affecting optical absorption, photoluminescence, and resonance Raman spectroscopies.ootnotetextJ. A. Fagan et al., J. Am. Chem. Soc. 129, 10607 (2007). Our samples include HiPco, CoMoCat, and arc-discharge SWCNTs dispersed in aqueous solutions by wrapping with either DNA or surfactant and exhibiting an exceptionally low degree of SWCNT bundling/clustering. Size-exclusion chromatography or density sorting ultracentrifugation collect length fractions ranging in size from approximately 50 nm to 1000 nm. The optical spectral weight specific to the SWCNT electronic states and photoluminescence peak emission intensity, compared to their underlying backgrounds, scale approximately linearly with length. All observed Raman vibrational modes exhibit a monotonic increase of scattering intensity with nanotube length. Resonance Raman of the radial breathing mode reveals a blueshift of the excitation energy for shorter nanotubes. Localization of bound excitons along the nanotube may explain the observed length-dependent optical properties.

  12. Header separation and reinsertion for 10-Gbit/s variable-length optical packets

    NASA Astrophysics Data System (ADS)

    Hatziefremidis, A.; Kehayas, E.; Tsiokos, D.; Kanellos, G. T.; Stampoulidis, L.; Pleros, N.; Avramopoulos, Hercules

    2005-03-01

    We report an all-optical module that performs simultaneous header separation and reinsertion in 10-Gbit/s short optical packets of variable payload length and that consists of two subunits. The first uses a Fabry-Perot filter and an ultrafast nonlinear interferometer (UNI) to perform packet clock recovery. The second is a UNI gate configured as a 2×2 exchange bypass switch that is optically controlled by the recovered clock packets. Using fixed delays, the data packets and the locally generated headers are fed into the 2×2 switch, where header replacement is achieved.

  13. Long gage-length fiber optic sensors for monitoring pipeline integrity

    Microsoft Academic Search

    R. C. Tennyson; W. D. Morison

    This paper describes the use of FOX-TEK's long gage-length FT fiber optic sensors (FOS) for monitoring the integrity of pipelines and refinery components. Site assessment protocols and installation methods are described, in addition to the different FOS configurations required to monitor component integrity. It is shown how sensor information can also be used for process control, involving the monitoring of

  14. Long gage-length fiber optic sensors for monitoring pipeline integrity

    Microsoft Academic Search

    R. C. Tennyson; W. D. Morison

    2006-01-01

    This paper describes the use of FOX-TEK's long gage-length FT fiber optic sensors (FOS) for monitoring the integrity of pipelines and refinery components. Site assessment protocols and installation methods are described, in addition to the different FOS configurations required to monitor component integrity. It is shown how sensor information can also be used for process control, involving the monitoring of

  15. Drawing of High-Strength Long-Length Optical Fibers for Submarine Cables

    Microsoft Academic Search

    SHIGEKI SAKAGUCHI

    1984-01-01

    A drawing process for high-strength long-length optical fibers intended for submarine cables was developed using a carbon resistance furnace. Surface treatment conditions for preforms as well as drawing furnace cleanliness for minimizing flaw formations on the fibers during the drawing process are described. Furthermore, an evaluation of the mechanical performance of long fibers is discussed on the basis of the

  16. 292 IEEE COMMUNICATIONS LETTERS, VOL. 4, NO. 9, SEPTEMBER 2000 Optical Buffers for Variable Length Packets

    E-print Network

    Shihada, Basem

    of the fiber delay line, as the crucial parameter that determines the queueing performance. Index Terms292 IEEE COMMUNICATIONS LETTERS, VOL. 4, NO. 9, SEPTEMBER 2000 Optical Buffers for Variable Length Packets Franco Callegati, Member, IEEE Abstract--This letter addresses the problem of dimensioning fiber

  17. Optical Path Length Factor at Near-Bandgap Wavelengths in Si Solar Cells

    Microsoft Academic Search

    Luigi Abenante

    2006-01-01

    By using the Rand and Basore (R&B) physical model for light trapping, a particular analytical expression for near-bandgap optical path length factor Zo is derived for the case where back surface reflectivity RBACK is equal to unity (RBACK = 1). This expression shows that according to the R&B physical model, at RBACK = 1, Zo has a finite value. At

  18. Modeling the temporal evolution of an aero-optical aberration with the minimum description length principle.

    PubMed

    Gao, Qiong; Jiang, Zongfu; Yi, Shihe

    2014-06-01

    A method of building a dynamical model for temporal evolution of an aero-optical aberration is presented. Based on the proper orthogonal decomposition (POD) of the optical aberration, the minimum description length (MDL) principle is used to select a dynamical model for the POD coefficients. The MDL principle can balance the model error against model size so as to prevent the model from overfitting. This strategy is validated with the numerical simulation of the aero-optical aberration caused by the supersonic mixing layer, and the model obtained can accurately predict the time evolution of the POD coefficients in short time. The potential application of our method in extending the bandwidth of the adaptive optics system is also discussed. PMID:24875993

  19. Optimal design of optical length in low turbidity measurement system with wavelength 1310 nm and 1550 nm

    NASA Astrophysics Data System (ADS)

    Cao, Hui-bin; Liu, Jian-guo; Gui, Hua-qiao; Wang, Jie; Wang, Huan-qin

    2014-11-01

    To meet the need of long distance transmission in low turbidity measurement system for low-loss, a new optical structure with wavelength 1310nm and 1550nm as the incident light is employed. In this research, experiments have been done for different optical length of the two wavelength light sources. The results show that: first, the transmitted light intensity has big difference under the circumstance of same concentration and optical length, though the loss has no remarkable difference transmitted in optical fiber between 1310nm and 1550nm. Second, the optimized optical length for better absorbance has been determined for 1310nm and 1550nm and it is irrelevant to the incident intensity. Third, the intensity of the two transmitted light decreases exponentially with the increase of optical length. For example, when the range of the optical length of 1310nm is 0.5mm-2mm, the transmitted intensity is about 60%-79% and the absorbance is 0.12-0.42. The transmitted intensity is about 5%-44%. When the range of the optical length of 1550nm is 0.5mm-2mm and the absorbance is still 0.12-0.42. Our experimental data provides the basis both for the optical length selection of these two light sources in water and the near-infrared spectral wavelength selection.

  20. Repository corticotropin injection in a patient presenting with focal segmental glomerulosclerosis, rheumatoid arthritis, and optic neuritis: a case report

    PubMed Central

    Madan, Arvind

    2015-01-01

    Background Focal segmental glomerulosclerosis (FSGS) causes scarring or sclerosis of glomeruli that act as tiny filters in the kidneys, damage to which results in diminished ability to properly filter blood, resulting in the urinary loss of plasma proteins and subsequent proteinuria. Case presentation A 60-year-old, white female with a history of intermittent proteinuria was referred by her primary care physician for renal dysfunction. Biopsy confirmed FSGS and she was treated with an angiotensin-converting enzyme inhibitor. She also had rheumatoid arthritis (RA) but no active synovitis and was maintained on prednisone 5 mg/d. She also complained of worsening vision in her right eye and was diagnosed with optic neuritis (ON). She remained stable for about 8 months when examination indicated FSGS relapse, and she reported painful RA flares. She was treated with Acthar® Gel (40 mg biweekly) for 6 months, after which proteinuria and urine protein-to-creatinine ratio decreased to about half. Her ON improved, and she reported that she had fewer RA flares and pain improved by 50%. This case of confirmed FSGS showed an improved response to treatment with Acthar Gel for FSGS with concomitant RA and ON. Conclusion This referral case is relevant to primary care practitioners who treat disorders that may be responsive to corticosteroid therapy. The antiproteinuric effects and ancillary improvement in RA and ON symptoms during treatment with Acthar Gel are not entirely explained by its steroidogenic actions. ACTH is a bioactive peptide that, together with ?-melanocyte-stimulating hormone, exhibits biologic efficacy by modulating proinflammatory cytokines and subsequent leukocyte extravasation and may have autocrine/paracrine effects in joints. While Acthar Gel was primarily administered in this case to treat proteinuria, it also showed ancillary benefits in patients with concomitant inflammatory disease states. PMID:25848316

  1. Long-term stabilization of the length of an optical reference cavity

    NASA Astrophysics Data System (ADS)

    Hagel, Gaëtan; Houssin, Marie; Knoop, Martina; Champenois, Caroline; Vedel, Michel; Vedel, Fernande

    2005-12-01

    To obtain a high degree of long-term length stabilization of an optical reference cavity, its free-spectral range is locked by means of an accurate and stable frequency synthesizer. The locking scheme is twofold: a laser is locked on the Nth mode of a reference Fabry-Perot cavity and part of the laser light is shifted in frequency to be in resonance with the (N +1)th mode of the cavity. This shift is generated by an acousto-optical modulator (AOM) mounted in a double-pass scheme, matching half of the free-spectral range of the reference cavity. The resulting absolute stabilization of the length of the cavity reaches the 10-11 level per second, limited by the lock transfer properties and the frequency stability of the AOM control synthesizer.

  2. Studies on the length of dry band arcs on ADSS fiber optic cables

    Microsoft Academic Search

    Baozhuang Shi; Qi Huang; G. G. Karady; M. W. Tuominen

    2003-01-01

    Arcing experiments are conducted in a laboratory setting to investigate the development of dry band arcing on ADSS fiber optic cables. The development of dry-band arcing within every power frequency cycle is filmed with a high-speed video camera and analyzed. The relationship between arc length and open-circuit voltage and short-circuit current is obtained. Studies show that the growth of arc

  3. Single-shot electron bunch length measurements using a spatial electro-optical autocorrelation interferometer

    SciTech Connect

    Suetterlin, Daniel [PUBLICA Swiss Federal Pension Fund, CH-3000 Berne (Switzerland); Paul Scherrer Institute, CH-5232 Villigen (Switzerland); Erni, Daniel [General and Theoretical Electrical Engineering (ATE), Faculty of Engineering, University of Duisburg-Essen, D-47048 Duisburg (Germany); Schlott, Volker [Department of Large Research Facilities, Paul Scherrer Institute, CH- 5232 Villigen (Switzerland); Sigg, Hans [Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, CH- 5232 Villigen (Switzerland); Jaeckel, Heinz [Department of Information Technology and Electrical Engineering, Electronics Laboratory, ETHZ, CH-8092 Zurich (Switzerland); Murk, Axel [Department of Microwave Physics, Institute of Applied Physics, University of Berne, CH-3012 Berne (Switzerland)

    2010-10-15

    A spatial, electro-optical autocorrelation (EOA) interferometer using the vertically polarized lobes of coherent transition radiation (CTR) has been developed as a single-shot electron bunch length monitor at an optical beam port downstream the 100 MeV preinjector LINAC of the Swiss Light Source. This EOA monitor combines the advantages of step-scan interferometers (high temporal resolution) [D. Mihalcea et al., Phys. Rev. ST Accel. Beams 9, 082801 (2006) and T. Takahashi and K. Takami, Infrared Phys. Technol. 51, 363 (2008)] and terahertz-gating technologies [U. Schmidhammer et al., Appl. Phys. B: Lasers Opt. 94, 95 (2009) and B. Steffen et al., Phys. Rev. ST Accel. Beams 12, 032802 (2009)] (fast response), providing the possibility to tune the accelerator with an online bunch length diagnostics. While a proof of principle of the spatial interferometer was achieved by step-scan measurements with far-infrared detectors, the single-shot capability of the monitor has been demonstrated by electro-optical correlation of the spatial CTR interference pattern with fairly long (500 ps) neodymium-doped yttrium aluminum garnet (Nd:YAG) laser pulses in a ZnTe crystal. In single-shot operation, variations of the bunch length between 1.5 and 4 ps due to different phase settings of the LINAC bunching cavities have been measured with subpicosecond time resolution.

  4. Correlation effects in the optical spectra of porphyrin oligomer chains: Exciton confinement and length dependence

    NASA Astrophysics Data System (ADS)

    Hogan, Conor; Palummo, Maurizia; Gierschner, Johannes; Rubio, Angel

    2013-01-01

    Excited states of ethylene-linked free-base porphyrin oligomers and polymer are studied using many-body perturbation theory (MBPT) within the GW approximation and the Bethe-Salpeter equation. Trends in the electronic levels with oligomer length are analysed and the correct long-range behaviour in the band gap is obtained. High polarizabilities and strong redshifts in the optical absorption peaks are predicted in agreement with observations on other strongly conjugated oligoporphyrins. We explain these trends by means of spatial and spectral analyses of the exciton character. Although Wannier-Mott and charge-transfer excitons are identified in the optical spectra, the strongest polarizabilities are actually associated with small, tightly bound excitons (Frenkel-like), in contrast to expectations. Furthermore, the common procedure of extrapolating polymer properties from oligomer calculations is examined from a MBPT perspective.

  5. Transit time of optical pulses propagating through a finite length medium.

    PubMed

    Bloemer, Mark; Myneni, Krishna; Centini, Marco; Scalora, Michael; D'Aguanno, Giuseppe

    2002-05-01

    We present experimental and theoretical results on the transit time of optical pulses propagating through bulk media of finite length, specifically GaAs and silica. The transit time of the peak of the pulse varies with the central wavelength due to the étalon effects caused by the reflectivity at the air/medium boundaries. For transform limited optical pulses, the transit time as a function of wavelength follows the transmittance spectrum, that is, the longest transit time occurs at the transmittance maxima where the cavity dwell time is the longest and the shortest transit time occurs at the transmittance minima. The results are dramatically different for chirped pulses obtained by modulating the injection current of a diode laser. The range in the transit times for chirped pulses is a factor of four times larger compared with transform limited pulses. In addition, the transit time for chirped pulses propagating through the GaAs sample is negative at certain wavelengths. Also, the transmitted pulse is not distorted. Although modulating the injection current of a diode laser is the most common method for generating optical pulses, to our knowledge this is the first reported observation of the transit time of these chirped optical pulses propagating through a simple étalon structure. PMID:12059739

  6. Lubrication Techniques to Allow Placement of Long Lengths of Innerduct and Fiber Optic Cable in a Conduit

    Microsoft Academic Search

    R. Machac

    1986-01-01

    Because of the present emphasis on placement of long unspliced lengths of fiber optic cable, conventional lubricants are being pushed to their limits. This paper discusses an installation where a newgeneration lubricant, consisting of silicone oil and tiny plastic ball bearings, was used to lower the effective coefficient of friction to 0.09. This allowed the contractor to place fiber optic

  7. Extended linear detection range for optical tweezers using a stop at the back focal plane of the condenser

    NASA Astrophysics Data System (ADS)

    Masoumeh Mousavi, S.; Samadi, Akbar; Hajizadeh, Faegheh; Reihani, S. Nader S.

    2015-06-01

    Optical tweezers are indispensable micro-manipulation tools. It is known that optical tweezers are force rather than position sensors due to the shorter linear range of their position detection system. In this paper, we have shown for the first time, that positioning an optical stop at the BFP of the condenser can overcome this problem by extending the linear detection range. This method would be valuable for the force spectroscopy applications of optical tweezers.

  8. A Method for Determining the Nominal Occular Hazard Zone for Gaussian Beam Laser Rangers with a Firmware Controlled Variable Focal Length

    NASA Technical Reports Server (NTRS)

    Picco, C. E.; Shavers, M. R.; Victor, J. M.; Duron, J. L.; Bowers, W. h.; Gillis, D. B.; VanBaalen, M.

    2009-01-01

    LIDAR systems that maintain a constant beam spot size on a retroreflector in order to increase the accuracy of bearing and ranging data must use a software controlled variable position lens. These systems periodically update the estimated range and set the position of the focusing lens accordingly. In order to precisely calculate the r NOHD for such a system, the software method for setting the variable position lens and gaussian laser propagation can be used to calculate the irradiance at any point given the range estimation. NASA s Space Shuttle LIDAR, called the Trajectory Control Sensor (TCS), uses this configuration. Analytical tools were developed using Excel and VBA to determine the radiant energy to the International Space Station (ISS) crewmembers eyes while viewing the shuttle on approach and departure. Various viewing scenarios are considered including the use of through-the-lens imaging optics and the window transmissivity at the TCS wavelength. The methodology incorporates the TCS system control logic, gaussian laser propagation, potential failure mode end states, and guidance from American National Standard for the Safe Use of Lasers (ANSI Z136.1-2007). This approach can be adapted for laser safety analyses of similar LIDAR systems.

  9. Coupling-length phase matching for nonlinear optical frequency conversion in parallel waveguides

    NASA Astrophysics Data System (ADS)

    Biaggio, Ivan; Coda, Virginie; Montemezzani, Germano

    2014-10-01

    We describe and analyze a quasi-phase-matching scheme for nonlinear optical frequency conversion where the spatial modulation of mode intensity in coupled parallel waveguides provides the required modulation in the generation of the frequency conversion signal, instead of a variation of any material parameter or propagation constant. We analyze this coupling-length phase-matching (CLPM) scheme both for second-order frequency conversion, such as second harmonic generation or difference-frequency generation, as well as for third-order four-wave mixing processes, for which we consider the example of generating a longer wavelength by third-order nonlinear mixing of two shorter wavelength waves. Numerous phase-matching conditions are identified in each case. We show that the maximum photon conversion efficiencies reached after an optimum propagation length are always higher than half those obtained for perfect phase matching in a single waveguide, with nearly 100% photon conversion possible for several of the CLPM conditions we studied.

  10. Ostrich ocular optics.

    PubMed

    Martin, G R; Ashash, U; Katzir, G

    2001-01-01

    The optical structure of the eyes of ostriches (Struthio camelus; Struthionidae; Struthioniformes) was determined by the construction of a schematic eye model for paraxial optics. The eye is large (axial length = 38 mm) and of globose shape with an anterior focal length (posterior nodal distance) of 21.8 mm. The optical design of the eye is such that the lens and cornea contribute equally to its total optical power. Interspecific comparison shows that optically the ostrich eye is a larger scaled version of the eyes of common starlings (Sturnus vulgaris) and an owl (Strix aluco). PMID:11805377

  11. Silicon micro machined binary lenses for infrared optics

    Microsoft Academic Search

    Lech Dobrzanski; Andrzej Kowalik; K. Gora; J. Piotrowski

    2002-01-01

    The refractive binary aplanatic lenses with dimensions of the wavelength scale have been fabricated and characterized by optical measurements. We fabricated lenses with f\\/D ratio close to one where f is the effective focal length and D is the lens diameter. Light intensity was measured on the focal surface of lenses using three independent methods and it has been demonstrated

  12. Compact color schlieren optical system

    NASA Technical Reports Server (NTRS)

    Buchele, Donald R.; Griffin, Devon W.

    1993-01-01

    A compact optical system for use with rainbow schlieren deflectometry is described. Both halves of the optical system consist of well-corrected telescopes whose refractive elements are all from manufacturer's stock catalogs, with the reflective primary being a spherical surface. As a result, the system is relatively easy to construct and meets the requirement of long focal length for quantitative rainbow schlieren measurements.

  13. Measurements of Cavity-Length-Dependent Internal Differential Quantum Efficiency and Internal Optical Loss in Laser Diodes

    Microsoft Academic Search

    Satoshi Inada; Masahiro Yoshita; Makoto Okano; Toshiyuki Ihara; Hidefumi Akiyama; Liming Zhang

    2008-01-01

    We measured the cavity length dependence of the internal differential quantum efficiency etaint and the internal optical loss alphaint in 1500-nm-wavelength laser diodes (LDs). By evaluating alphaint directly from gain\\/absorption spectra for various injection current densities and measuring the external differential quantum efficiency etaext, we obtained the etaint and alphaint values of all the LDs with different cavity lengths. The

  14. Development of transrectal diffuse optical tomography combined with 3D-transrectal ultrasound imaging to monitor the photocoagulation front during interstitial photothermal therapy of primary focal prostate cancer

    NASA Astrophysics Data System (ADS)

    He, Jie; Weersink, Robert; Veilleux, Israel; Mayo, Kenwrick; Zhang, Anqi; Piao, Daqing; Alam, Adeel; Trachtenberg, John; Wilson, Brian C.

    2013-03-01

    Interstitial near-infrared laser thermal therapy (LITT) is currently undergoing clinical trials as an alternative to watchful waiting or radical surgery in patients with low-risk focal prostate cancer. Currently, we use magnetic resonance image (MRI)-based thermography to monitor treatment delivery and determine indirectly the completeness of the target tissue destruction while avoiding damage to adjacent normal tissues, particularly the rectal wall. However, incomplete tumor destruction has occurred in a significant fraction of patients due to premature termination of treatment, since the photocoagulation zone is not directly observed. Hence, we are developing transrectal diffuse optical tomography (TRDOT), in combination with transrectal 3D ultrasound (3D-TRUS), to address his limitation. This is based on the large changes in optical scattering expected upon tissue coagulation. Here, we present forward simulations of a growing coagulated lesion with optical scattering contrast, using an established finite element analysis software platform (NIRFAST). The simulations were validated in tissue-simulating phantoms, with measurements acquired by a state-of-the-art continuous wave (CW) TRDOT system and a recently assembled bench-top CW-DOT system, with specific source-detector configurations. Two image reconstruction schemes were investigated and evaluated, specifically for the accurate delineation of the posterior boundary of the coagulation zone as the critical parameter for treatment guidance in this clinical application.

  15. Axial length measurement acquisition rates of two optical biometers in cataractous eyes

    PubMed Central

    Epitropoulos, Alice

    2014-01-01

    Purpose To compare the ability of two optical biometers to acquire the axial length (AL) measurement in cataractous eyes. Methods This prospective, comparative, single-center study comprised 105 eyes (63 patients). AL was acquired by the composite mean value of 20 measurements (composite-20 IM) and five measurements (composite-5 IM) (IOLMaster® 500 version 7.1 software), and the standard mean value of the first five measurements (standard-5 LS, Lenstar LS 900®). Anterior chamber depth (ACD) and average keratometry (K) readings were acquired. Results AL was acquired in 83.8%, 92.4%, and 84.8% of eyes for the composite-5 IM, composite-20 IM, and standard-5 LS, respectively. Standard-5 LS AL measurements were significantly shorter (P<0.001). IOLMaster® 500-acquired ACD (corneal epithelium to lens) measurements were significantly shorter (P<0.001). IOLMaster® 500 average K measurements were significantly steeper (P<0.001). Conclusion The composite-20 IM had the highest AL acquisition success rate of the three versions evaluated. AL, ACD, and average Ks were statistically different between the two biometers, although the differences were clinically insignificant. PMID:25092960

  16. Production and installation of long length optical fiber cable for shallow water use

    Microsoft Academic Search

    T. Ohshima; H. Horima; Y. Tokumaru; K. Aoto; T. Higashimoto

    1986-01-01

    Accompanying the expansion of optical fiber communication systems, needs for optical submarine cables have been increased particularly in off-shore areas, shallow channels and bays. Optical fiber cables to be layed on the sea bottom must be protected from damages during installation and extended use. The problems presented by these optical fiber cables are similar to those of conventional metal cables.

  17. Active optics Shack-Hartmann sensor: using spot sizes to measure the seeing at the focal plane of a telescope

    NASA Astrophysics Data System (ADS)

    Martinez, P.; Kolb, J.; Sarazin, M.; Navarrete, J.

    2012-04-01

    Nowadays, the real-time seeing estimation at the focus of a telescope is strongly emphasized because this knowledge virtually drives the dimensioning of adaptive optics systems and the operational aspects of instruments. In this context, we study the importance of using images from an active optics Shack-Hartmann (AOSH) sensor to provide accurate estimates of the seeing. At the critical location of the focus of the telescope, the AOSH sensor delivers long-exposure spot point spread functions, which are directly related to the atmospheric seeing in the line of sight. Although AOSH sensors are specified to measure not spot sizes but slopes, we show that an accurate estimation of the seeing can be obtained from AOSH images using a dedicated algorithm. We analyse the sensitivity of two algorithms and compare them to various parameters in a systematic way, demonstrating that an efficient estimation of the seeing can be obtained by adequate means.

  18. Pillar cuvettes: capillary-filled, microliter quartz cuvettes with microscale path lengths for optical spectroscopy.

    PubMed

    Holzner, Gregor; Kriel, Frederik Hermanus; Priest, Craig

    2015-05-01

    The goal of most analytical techniques is to reduce the lower limit of detection; however, it is sometimes necessary to do the opposite. High sample concentrations or samples with high molar absorptivity (e.g., dyes and metal complexes) often require multiple dilution steps or laborious sample preparation prior to spectroscopic analysis. Here, we demonstrate dilution-free, one-step UV-vis spectroscopic analysis of high concentrations of platinum(IV) hexachloride in a micropillar array, that is, "pillar cuvette". The cuvette is spontaneously filled by wicking of the liquid sample into the micropillar array. The pillar height (thus, the film thickness) defines the optical path length, which was reduced to between 10 and 20 ?m in this study (3 orders of magnitude smaller than in a typical cuvette). Only one small droplet (?2 ?L) of sample is required, and the dispensed volume need not be precise or even known to the analyst for accurate spectroscopy measurements. For opaque pillars, we show that absorbance is linearly related to platinum concentration (the Beer-Lambert Law). For fully transparent or semitransparent pillars, the measured absorbance was successfully corrected for the fractional surface coverage of the pillars and the transmittance of the pillars and reference. Thus, both opaque and transparent pillars can be applied to absorbance spectroscopy of high absorptivity, microliter samples. It is also shown here that the pillar array has a useful secondary function as an integrated (in-cuvette) filter for particulates. For pillar cuvette measurements of platinum solutions spiked with 6 ?m diameter polystyrene spheres, filtered and unfiltered samples gave identical spectra. PMID:25844800

  19. Optical elements with extended depth of focus and arbitrary distribution of intensity along the focal segment obtained by angular modulation of the optical power

    NASA Astrophysics Data System (ADS)

    Kakarenko, K.; Ducin, I.; Jaroszewicz, Z.; Ko?odziejczyk, A.; Petelczyc, K.; Stompor, A.; Sypek, M.

    2015-04-01

    Light Sword Lens (LSL), i.e., an optical element with extended depth of focus (EDOF) characterized by angular modulation of the optical power in its conventional form is characterized by a linear relationship between the optical power and the angular coordinate of the corresponding angular lens sector. This dependence may be manipulated in function of the required design needs. In the present communicate this additional degree of freedom of design is used for elimination of the LSL shape discontinuity.

  20. Fiber-length extension in an optical 60GHz transmission system using an EA-modulator with negative chirp

    Microsoft Academic Search

    A. Stohr; K. Kitayama; T. Kuri

    1999-01-01

    By optimizing the driving conditions of a highspeed electroabsorption modulator, we achieved a significant fiber-length extension and dispersion penalty reduction in a 60-GHz millimeter-wave indoor fiber-optic transmission system. In particular, we demonstrate simultaneous transmission of two 156-Mb\\/s data channels in the 60-GHz band over 1409-m standard single-mode fiber without employing an additional dispersion compensation technique

  1. Explicit solutions for the band edges of multi-layer photonic crystals with integer ratios of optical path lengths

    Microsoft Academic Search

    Frank Szmulowicz

    2007-01-01

    The tangent formulation for photonic bandgap materials is used to derive explicit expressions for the energy eigenvalues at the centre and the edge of the Brillouin zone of multi-layer photonic bandgap materials with integer ratios of optical path lengths (e.g. any combination of quarter-wave, half-wave, etc., stacks). Unlike the transfer matrix formalism---in which such solutions are implicit functions of photon

  2. Beam Quality Dependence on the Coherence Length of Gaussian Schell-model fields Propagating Through ABCD Optical Systems

    Microsoft Academic Search

    J. Serna; P. M. Mejías; R. Martínez-Herrero

    1992-01-01

    The quality behaviour of Gaussian Schell-model fields propagating through general (non-orthogonal) ABCD optical systems has been characterized by introducing a number of parameters. Such parameters have been given in terms of the Wigner distribution function of the field, closely connected with its second-order coherence features. Dependence of the focusing capabilities, transversal widths and beam asymmetry on the coherence length of

  3. Design of a Simple Detection Cell with Extended Optical Path Length for Capillary Electrophoresis: Application to Multiresidue Pesticide Analysis

    Microsoft Academic Search

    Mário S. Galhiane; Sandra R. Rissato; Bernhard M. Apon

    2005-01-01

    Absorbance detection in capillary electrophoresis (CE), offers an excellent mass sensitivity, but poor concentration detection limits owing to very small injection volumes (normally 1 to 10 nL). This aspect can be a limiting factor in the applicability of CE\\/UV to detect species at trace levels, particularly pesticide residues. In the present work, the optical path length of an “on?column” detection cell

  4. Optical Properties of Single-Walled Carbon Nanotubes Separated in a Density Gradient; Length, Bundling, and Aromatic Stacking Effects.

    PubMed

    Tabakman, Scott M; Welsher, Kevin; Hong, Guosong; Dai, Hongjie

    2010-10-28

    Single-walled carbon nanotubes (SWNTs) are promising materials for in vitro and in vivo biological applications due to their high surface area and inherent near infrared photoluminescence and Raman scattering properties. Here, we use density gradient centrifugation to separate SWNTs by length and degree of bundling. Following separation, we observe a peak in photoluminescence quantum yield (PL QY) and Raman scattering intensity where SWNT length is maximized and bundling is minimized. Individualized SWNTs are found to exhibit high PL QY and high resonance-enhanced Raman scattering intensity. Fractions containing long, individual SWNTs exhibit the highest PL QY and Raman scattering intensities, compared to fractions containing single, short SWNTs or SWNT bundles. Intensity gains of approximately ~1.7 and 4-fold, respectively, are obtained compared with the starting material. Spectroscopic analysis reveals that SWNT fractions at higher displacement contain increasing proportions of SWNT bundles, which causes reduced optical transition energies and broadening of absorption features in the UV-Vis-NIR spectra, and reduced PL QY and Raman scattering intensity. Finally, we adsorb small aromatic species on "bright," individualized SWNT sidewalls and compare the resulting absorption, PL and Raman scattering effects to that of SWNT bundles. We observe similar effects in both cases, suggesting aromatic stacking affects the optical properties of SWNTs in an analogous way to SWNT bundles, likely due to electronic structure perturbations, charge transfer, and dielectric screening effects, resulting in reduction of the excitonic optical transition energies and exciton lifetimes. PMID:21258607

  5. Atom optical shop testing of electrostatic lenses using an atom interferometer Ivan Hromada1

    E-print Network

    Cronin, Alex D.

    Atom optical shop testing of electrostatic lenses using an atom interferometer Ivan Hromada1 optical shop testing of lenses for atomic de Broglie waves. We measured focal lengths and spherical of Physics, University of Arizona, Tucson, Arizona 85721, USA and 2 College of Optical Sciences, University

  6. Space telescope optical telescope assembly/scientific instruments. Phase B: Preliminary design and program definition study. Volume 2A. focal plane camera

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Trade studies were conducted to ensure the overall feasibility of the focal plane camera in a radial module. The primary variable in the trade studies was the location of the pickoff mirror, on axis versus off-axis. Two alternatives were: (1) the standard (electromagnetic focus) SECO submodule, and (2) the MOD 15 permanent magnet focus SECO submodule. The technical areas of concern were the packaging affected parameters of thermal dissipation, focal plane obscuration, and image quality.

  7. Imaging and full-length biometry of the eye during accommodation using spectral domain OCT with an optical switch

    PubMed Central

    Ruggeri, Marco; Uhlhorn, Stephen R.; De Freitas, Carolina; Ho, Arthur; Manns, Fabrice; Parel, Jean-Marie

    2012-01-01

    Abstract: An optical switch was implemented in the reference arm of an extended depth SD-OCT system to sequentially acquire OCT images at different depths into the eye ranging from the cornea to the retina. A custom-made accommodation module was coupled with the delivery of the OCT system to provide controlled step stimuli of accommodation and disaccommodation that preserve ocular alignment. The changes in the lens shape were imaged and ocular distances were dynamically measured during accommodation and disaccommodation. The system is capable of dynamic in vivo imaging of the entire anterior segment and eye-length measurement during accommodation in real-time. PMID:22808424

  8. Application of optical design software in the analysis of "unknown" optical systems

    NASA Astrophysics Data System (ADS)

    Roudnicky, Dunja S.

    1998-08-01

    Optical design software is not very usable in designing new optical systems only, but also in analysis of `unknown' systems. When measurements of radii of curvature, focal lengths and axial thickness of elements are done, we use SIGMA 2100 Optical design software (Kidger Optics). We determine which optical glass fits the nearest measured focal length of each element. We also get aberration curves of elements and the whole system. In such a way we analyze elements of an eyepiece which is the part of a compound panoramic sight. Since we now have all specifications of this eyepiece, it is possible to optimize glasses and radii to the more convenient ones, without a risk to change the performance of the whole optical system. This method gives us a possibility of reparation and adaptation of `unknown' optical systems with a high yield.

  9. Adaptive beam shaping by controlled thermal lensing in optical elements

    Microsoft Academic Search

    Muzammil A. Arain; Volker Quetschke; Joseph Gleason; Luke F. Williams; Malik Rakhmanov; Jinho Lee; Rachel J. Cruz; Guido Mueller; D. B. Tanner; David. H. Reitze

    2007-01-01

    We describe an adaptive optical system for use as a tunable focusing element. The system provides adaptive beam shaping via controlled thermal lensing in the optical elements. The system is agile, remotely controllable, touch free, and vacuum compatible; it offers a wide dynamic range, aberration-free focal length tuning, and can provide both positive and negative lensing effects. Focusing is obtained

  10. Designing optical path length, photonic, and plasmonic effects into nanostructured solar cells

    Microsoft Academic Search

    Wook Jun Nam; Liming Ji; Vasundara V. Varadan; Stephen J. Fonash

    2011-01-01

    The numerical modeling presented here shows the carrier collection and light management potential of nano-scale structure designs in solar cells. This design evaluation procedure includes scattering phenomena arising from photonic (periodic structure) and plasmonic effects and also the effective absorber length impact arising from morphology. This design work points to short circuit current densities of over 17mA\\/cm2 being attainable under

  11. Short length of single walled-carbon nano tubes for application to optical devices

    Microsoft Academic Search

    S. Kato; Y. Miyazaki; T. Takashima; K. Utaka

    2010-01-01

    Carbon nano tubes (CNT) attracts attention in the field of optical communication. However, CNT is too long as it is compared with the wavelength of communication wavelength and causes the scattering. So we could make CNT short and fat, and our devise showed saturable absorption.

  12. Follow up of focal narrowing of retinal arterioles in glaucoma

    PubMed Central

    Papastathopoulos, K.; Jonas, J.

    1999-01-01

    AIM—To evaluate whether focal narrowing of retinal arterioles increases with progressive glaucomatous optic neuropathy.?METHODS—Focal narrowing of retinal arterioles and area of neuroretinal rim were morphometrically evaluated on colour stereo optic disc photographs of 59 patients with primary open angle glaucoma, 22 patients with normal pressure glaucoma, 11 patients with secondary open angle glaucoma, and 31 patients with ocular hypertension. Minimum follow up was 8 months. Focal arteriolar narrowing was quantified by calculating the ratio of the vessel width in the broadest to the narrowest vessel part.?RESULTS—In the subgroup of patients with progressive glaucomatous optic nerve damage (n=37), focal narrowing of retinal arterioles increased significantly (p<0.005) with decreasing neuroretinal rim area. In the subgroup of patients with stable appearance of the optic disc (n=86), focal narrowing of retinal arterioles did not change significantly (p=0.79). The positive correlation between increasing focal thinning of retinal arterioles and progression of glaucomatous optic neuropathy was present, although not statistically significant, in all the glaucoma subtypes examined. The location of focal thinning of retinal arterioles did not change in the follow up.?CONCLUSIONS—Focal narrowing of retinal arterioles increases significantly with progressive glaucomatous optic neuropathy, independent of the type of glaucoma. It is stable in patients with non-progressive glaucoma. The findings agree with previous reports on a higher degree of focal arteriole narrowing in eyes with pronounced optic nerve damage in comparison with those with moderate optic nerve atrophy or normal eyes. In the clinical management of patients with glaucoma, in some eyes, increasing focal arteriole narrowing may suggest progression of disease.?? Keywords: focal narrowing; retinal arterioles; glaucoma PMID:10365034

  13. Influence of three anionic gemini surfactants with different chain lengths on the optical properties of a cationic polyfluorene.

    PubMed

    Liu, Xue-Guo; Xing, Xiao-Jing; Gao, Zhi-Nong; Wang, Bao-Shan; Tai, Shu-Xin; Tang, Hong-Wu

    2014-03-25

    The effects of three sulfonate gemini surfactants with different hydrophobic chain lengths (8, 10, and 12 carbon atoms) on the optical properties of a fluorene-based conjugated cationic polymer poly{[9,9-bis(6'-N,N,N-trimethylammonium)hexyl]-fluorene-phenylene} bromide (PFP) dissolved in DMSO-water solutions (4% v/v) or water were investigated, respectively. When surfactants with PFP dissolved in DMSO-water solutions (4% v/v) are incubated, a decrease in photoluminescence (PL) intensity and a red shift of emission maxima are obtained at low surfactant concentrations. Intriguingly, two different Stern-Volmer constants (KSV1 and KSV2) are obtained and analyzed in detail for the first time. Further increase in the surfactant concentration enhanced PL intensity, and distinct blue shifts of both absorption and emission maxima are observed. Importantly, the turning point between the emission quenching and enhancement is closely related to the hydrophobic chain length: the longer the chain length, the earlier the turning point appears. Simulation studies provide strong evidence to explain these phenomena. Surface tension measurements show more insight on the interactions between PFP and surfactant. On the contrary, no emission quenching is obtained at low surfactant concentrations for PFP dissolved in water. PMID:24571294

  14. Optical Free-Path-Length Distribution in a Fractal Aggregate and its Effect on Enhanced Backscattering

    NASA Astrophysics Data System (ADS)

    Ishii, Katsuhiro; Iwai, Toshiaki; Uozumi, Jun; Asakura, Toshimitsu

    1998-07-01

    A free-path-length distribution function (FPDF) of multiply backscattered light is theoretically derived for a fractal aggregate of particles. An effective mean-free path-length l D is newly introduced as a measure of randomness analogous with a homogeneously random medium. We confirm the validity of the FPDF by demonstrating agreement between the dimensions designed for a particle distribution generated by a random walk based on the derived FPDF and estimated by the radius of gyration method. The FPDF is applied to Monte Carlo simulations for copolarized multiply backscattered light from the fractal aggregate of particles. It is shown that a copolarized intensity peak of enhanced backscattering in the far field decreases in accordance with 2 D and has an angular width of l D . This spatial feature of the backscattering enhancement corresponds to that of the copolarized intensity peak produced from a homogeneously random medium with a dimension of D 3 . As a result, the validity of the model for the fractal structure of particle aggregates and the applicability of the derived FPDF are confirmed by the numerical results.

  15. Compact Color Schlieren Optical System

    NASA Technical Reports Server (NTRS)

    Buchele, Donald R.; Griffin, Devon W.

    1996-01-01

    Compact, rugged optical system developed for use in rainbow schlieren deflectometry. Features unobscured telescope with focal-length/aperture-width ratio of 30. Made of carefully selected but relatively inexpensive parts. All of lenses stock items. By-product of design is optical system with loose tolerances on interlens spacing. One of resulting advantages, insensitivity to errors in fabrication of optomechanical mounts. Another advantage is ability to compensate for some of unit-to-unit variations inherent in stock lenses.

  16. Picosecond electron bunch length measurement by electro-optic detection of the Wakefield

    SciTech Connect

    M. J. Fitch, A. C. Melissinos and P. L. Colestock

    1999-05-17

    The longitudinal profile of an 10 nC electron bunch of a few picoseconds duration will be measured by electro-optic detection of the wakefield. The polarization of a short in-frared probe laser pulse (derived from the photocathode excitation laser) is modulated in a LiTaO3 crystal by the transient electric field of the bunch. The bunch profile is measured by scanning the delay between the laser and the bunch, and is sensitive to head/tail asymmetries. A single-shot extension of the technique is possible using a longer chirped laser pulse.

  17. X-ray Pulse Length Characterization using the Surface Magneto Optic Kerr Effect

    SciTech Connect

    Krejcik, P.; /SLAC

    2006-10-04

    It will be challenging to measure the temporal profile of the hard X-ray SASE beam independently from the electron beam in the LCLS and other 4th generation light sources. A fast interaction mechanism is needed that can be probed by an ultrafast laser pulse in a pump-probe experiment. It is proposed to exploit the rotation in polarization of light reflected from a thin magnetized film, known as the surface magneto optic Kerr effect (SMOKE), to witness the absorption of the x-ray pulse in the thin film. The change in spin orbit coupling induced by the x-ray pulse occurs on the subfemtosecond time scale and changes the polarization of the probe beam. The limitation to the technique lies with the bandwidth of the probe laser pulse and how short the optical pulse can be made. The SMOKE mechanism will be described and the choices of materials for use with 1.5 {angstrom} x-rays. A schematic description of the pump-probe geometry for x-ray diagnosis is also described.

  18. Single molecule microscopy using focal plane illumination

    Microsoft Academic Search

    Jörg Ritter; Werner Wendler; Ulrich Kubitscheck

    Single molecule fluorescence microscopy performed in spatially extended samples such as living cells usually suffers from a high fluorescence background. To overcome this problem we used a selective focal plane illumination instead of the conventional epi-illumination. By means of a custom made cylindrical lens system (NA 0.33) we created a light sheet with a Rayleigh length of 37 µm, a

  19. Focal Cortical Dysplasia.

    PubMed

    Crino, Peter B

    2015-06-01

    Focal cortical dysplasias are common malformations of cerebral cortical development and are highly associated with medically intractable epilepsy. They have been classified into neuropathological subtypes (type Ia, Ib, IIa, IIb, and III) based on the severity of cytoarchitectural disruption-tangential or radial dispersion, or loss of laminar structure-and the presence of unique cells types such as cytomegalic neurons or balloon cells. Most focal cortical dysplasias can be identified on neuroimaging and many require resective epilepsy surgery to cure refractory seizures. The pathogenesis of focal cortical dysplasias remains to be defined, although there is recent evidence to suggest that focal cortical dysplasias arise from de novo somatic mutations occurring during brain development. Some focal cortical dysplasia subtypes show a link to the mammalian target of rapamycin signaling cascade; this has now extended to other cortical malformations, including hemimegalencephaly. PMID:26060899

  20. Bunch Length Monitoring at the A0 Photoinjector Using a Quasi-Optical Schottky Detector

    SciTech Connect

    Kazakevich, G.; Davidsaver, M.; Edwards, H.; Fliller, R.; Koeth, T.; Lumpkin, A.; Nagaitsev, S.; Ruan, J.; Thurman-Keup, R.; /Fermilab; Jeong, Y.U.; /KAERI, Taejon; Kubarev, V.; /Novosibirsk, IYF

    2009-05-01

    Noninvasive bunch duration monitoring has a crucial importance for modern accelerators intended for short wavelength FEL's, colliders and in some beam dynamics experiments. Monitoring of the bunch compression in the Emittance Exchange Experiment at the A0 Photoinjector was done using a parametric presentation of the bunch duration via Coherent Synchrotron Radiation (CSR) emitted in a dipole magnet and measured with a wideband quasi-optical Schottky Barrier Detector (SBD). The monitoring resulted in a mapping of the quadrupole parameters allowing a determination of the region of highest compression of the bunch in the sub-picosecond range. The obtained data were compared with those measured using the streak camera. A description of the technique and the results of simulations and measurements are presented and discussed in this report.

  1. Optical microcavities enhance the exciton coherence length and eliminate vibronic coupling in J-aggregates

    NASA Astrophysics Data System (ADS)

    Spano, F. C.

    2015-05-01

    The properties of polaritons in J-aggregate microcavities are explored using a Hamiltonian which treats exciton-vibrational coupling and exciton-photon coupling on equal footing. When the cavity mode is resonant with the lowest-energy (0-0) transition in the J-aggregate, two polaritons are formed, the lowest-energy polariton (LP) and its higher-energy partner (P1), separated by the Rabi splitting. Strong coupling between the material and cavity modes leads to a decoupling of the exciton and vibrational degrees of freedom and an overall reduction of disorder within the LP. Such effects lead to an expanded material coherence length in the LP which leads to enhanced radiative decay rates. Additional spectral signatures include an amplification of the 0-0 peak coincident with a reduction in the 0-1 peak in the photoluminescence spectrum. It is also shown that the same cavity photon responsible for the LP/P1 splitting causes comparable splittings in the higher vibronic bands due to additional resonances between vibrationally excited states in the electronic ground state manifold and higher energy vibronic excitons.

  2. Optical microcavities enhance the exciton coherence length and eliminate vibronic coupling in J-aggregates.

    PubMed

    Spano, F C

    2015-05-14

    The properties of polaritons in J-aggregate microcavities are explored using a Hamiltonian which treats exciton-vibrational coupling and exciton-photon coupling on equal footing. When the cavity mode is resonant with the lowest-energy (0-0) transition in the J-aggregate, two polaritons are formed, the lowest-energy polariton (LP) and its higher-energy partner (P1), separated by the Rabi splitting. Strong coupling between the material and cavity modes leads to a decoupling of the exciton and vibrational degrees of freedom and an overall reduction of disorder within the LP. Such effects lead to an expanded material coherence length in the LP which leads to enhanced radiative decay rates. Additional spectral signatures include an amplification of the 0-0 peak coincident with a reduction in the 0-1 peak in the photoluminescence spectrum. It is also shown that the same cavity photon responsible for the LP/P1 splitting causes comparable splittings in the higher vibronic bands due to additional resonances between vibrationally excited states in the electronic ground state manifold and higher energy vibronic excitons. PMID:25978905

  3. Influence of laser linewidth and polarization modulator length on polarization shift keying for free space optical communication.

    PubMed

    Han, Biao; Zhao, Wei; Xie, Xiaoping; Su, Yulong; Wang, Wei; Hu, Hui

    2015-04-01

    Modulating signal with polarization modulator (PolM) is the simplest method for polarization shift keying (PolSK) in free space optical communication. However, this method has an intrinsic drawback on degree of polarization (DOP) reduction for the existence of polarization mode dispersion (PMD) in PolM. In this work, we analyze this change of DOP and its influence on PolSK using coherency matrix. We demonstrate that the decrease of DOP after PolM will generate extra loss and bit error ratio (BER) for PolSK communication, while this loss and BER will aggravate with the increase of laser linewidth and PolM length. For a practical PolSK system, laser linewidth should be less than 0.008nm. PMID:25968702

  4. Thin plastic foil X-ray optics with spiral geometry

    NASA Astrophysics Data System (ADS)

    Barbera, Marco; Mineo, Teresa; Perinati, Emanuele; Schnopper, Herbert W.; Taibi, Angelo

    2007-09-01

    Winding a plastic foil ribbon into spiral cylinder or spiral cones we can design and build single or multiple reflection X-ray grazing incidence focusing optics with potential applications in Astronomy as well as experimental physics. The use of thin plastic foils from common industrial applications and of a mounting technique which does not require the construction of mandrels make these optics very cost effective. A spiral geometry focusing optic produces an annular image of a point source with the angular size of the annulus depending mainly on the pitch of the winding and the focal length. We use a ray-tracing code to evaluate the performances of cylindrical, and double conical spiral geometry as a function of the design parameters e.g. focal length, diameter, optic length. Some preliminary results are presented on X-ray imaging tests performed on spiral cylindrical optics.

  5. Optical Design of a Broadband Infrared Spectrometer for Bunch Length Measurement at the Linac Coherent Light Source

    SciTech Connect

    Williams, Kiel; /SLAC

    2012-09-07

    The electron pulses generated by the Linac Coherent Light Source at the SLAC National Accelerator Laboratory occur on the order of tens of femtoseconds and cannot be directly measured by conventional means. The length of the pulses can instead be reconstructed by measuring the spectrum of optical transition radiation emitted by the electrons as they move toward a conducting foil. Because the emitted radiation occurs in the mid-infrared from 0.6 to 30 microns a novel optical layout is required. Using a helium-neon laser with wavelength 633 nm, a series of gold-coated off-axis parabolic mirrors were positioned to direct a beam through a zinc selenide prism and to a focus at a CCD camera for imaging. Constructing this layout revealed a number of novel techniques for reducing the aberrations introduced into the system by the off-axis parabolic mirrors. The beam had a recorded radius of less than a millimeter at its final focus on the CCD imager. This preliminary setup serves as a model for the spectrometer that will ultimately measure the LCLS electron pulse duration.

  6. Fabrication of ZnO nanorods and assessment of changes in optical and gas sensing properties by increasing their lengths

    NASA Astrophysics Data System (ADS)

    Mehrabian, Masood; Mirabbaszadeh, Kavoos; Afarideh, Hossein

    2013-12-01

    We report a low-temperature process to synthesize highly oriented arrays of ZnO nanorods, based on the epitaxial growth of the ZnO seed layer at a low temperature of 70 °C. The ZnO seed layer was deposited by sol-gel process under mild conditions on the glass substrates. The morphologies and crystal structures of the film and nanorods were characterized by x-ray diffraction and scanning electron microscopy, respectively. ZnO nanorods were grown on ZnO seed layers by hydrothermal method. The effect of growth period on the morphology and optical characteristics (e.g. optical transmission and band-gap energy), hydrophilicity and gas sensing properties of the grown ZnO seed layer (film) and nanorods were investigated. The long nanorods on the seed layer were observed. The increase in the length of the nanorods resulted in a significant reduction in the optical band-gap energy of the nanorods, which was attributed to the formation of further defects in the nanorods during their fast growth. The surface of the ZnO nanorods grown for 6 h was relatively hydrophilic (with a water contact angle of 18°). The fabricated sensors were used to gauge different concentrations of ethanol vapor in the air at different temperatures and evaluated the surface resistance of the sensors as a function of operating temperature and ethanol concentrations. The results showed that the sensitivity of the nanorods changed from 1.3 to 6 (at 300 °C) by increasing the growth period.

  7. A Biomimetic Focal Plane Speed Computation Architecture Vivek Pant1

    E-print Network

    A Biomimetic Focal Plane Speed Computation Architecture Vivek Pant1 and Charles M. Higgins1,2 1 speed at the image focal plane for robotic navigation. It employs an array of parallel sensing and computing blocks, and outputs a signal that varies linearly with image speed. ©2007 Optical Society

  8. Focal plane metrology for the LSST camera

    Microsoft Academic Search

    Andrew P. Rasmussen; Layton Hale; Peter Kim; Eric Lee; Martin Perl; Rafe Schindler; Peter Takacs; Timothy Thurston

    2006-01-01

    Meeting the science goals for the Large Synoptic Survey Telescope (LSST) translates into a demanding set of imaging performance requirements for the optical system over a wide (3.5°) field of view. In turn, meeting those imaging requirements necessitates maintaining precise control of the focal plane surface (10 mum P-V) over the entire field of view (640 mm diameter) at the

  9. |September 2004| SPIE's oemagazine |25 enses are key elements of optical systems. Most con-

    E-print Network

    Wu, Shin-Tson

    |September 2004| SPIE's oemagazine |25 L enses are key elements of optical systems. Most con- ventional lenses are made of glass, polymer, or other transparent solid materials. These lenses have fixed focus. To tune the focal length continuously, optical design- ers have developed the zoom lens, which

  10. A unique, accurate LWIR optics measurement system

    NASA Astrophysics Data System (ADS)

    Fantone, Stephen D.; Orband, Daniel G.

    2011-05-01

    A compact low-cost LWIR test station has been developed that provides real time MTF testing of IR optical systems and EO imaging systems. The test station is intended to be operated by a technician and can be used to measure the focal length, blur spot size, distortion, and other metrics of system performance. The challenges and tradeoffs incorporated into this instrumentation will be presented. The test station performs the measurement of an IR lens or optical system's first order quantities (focal length, back focal length) including on and off-axis imaging performance (e.g., MTF, resolution, spot size) under actual test conditions to enable the simulation of their actual use. Also described is the method of attaining the needed accuracies so that derived calculations like focal length (EFL = image shift/tan(theta)) can be performed to the requisite accuracy. The station incorporates a patented video capture technology and measures MTF and blur characteristics using newly available lowcost LWIR cameras. This allows real time determination of the optical system performance enabling faster measurements, higher throughput and lower cost results than scanning systems. Multiple spectral filters are also accommodated within the test stations which facilitate performance evaluation under various spectral conditions.

  11. Biomimetic optical system using polymer lenses with tunable focus

    NASA Astrophysics Data System (ADS)

    Liang, Dan; Xiang, Ke; Du, Jia-Wei; Yang, Jun-Nan; Wang, Xuan-Yin

    2014-10-01

    A biomimetic system using polymer lenses for the optical design and application is developed. The system mainly consisted of a bionic cornea lens, voice coil motor, compression ring, bionic crystalline lens, substrate, and CCD sensor. By controlling the current of the voice coil motor, we could change the motion of the compression ring to alter the curvature radius of the bionic crystalline lens, thus adjusting the focal length of the whole system. The integrated constructure of the optical system was presented, as well as the detailed description of the lens composition, material, and fabrication process. Images under different displacement loads were captured, the relationship among the curvature radius, observed back focal length, and predicted effective focal length was analyzed, and the spot diagram of the optical system was simulated using ZEMAX software. The focal length of the optical system ranged from 17.3 to 24.5 mm under a tiny displacement load from 0 to 0.14 mm. Besides, the images captured at different rotating angles presented almost identical patterns and the same image quality, which showed good robustness to the gravity. The biomimetic optical system is of interest to develop an integrated, low-cost, and stable imaging system.

  12. Optical design of athermalization stepping-zoom dual FOV MWIR system

    NASA Astrophysics Data System (ADS)

    Du, Ping; Zhao, Cui-ling; Geng, Yaguang; Ma, Tao

    2015-03-01

    According to the athermalization theory a optical passive athermalization stepping-zoom dual FOV MWIR system in 3?m?5?m designed in this paper, Through the rational combination of infrared optical materials and aspheric surface realized the design of optical passive athermalization. The optical system only use five lens and the optical materials is commonly such as germanium, silicon and Znse. The focal length is 90mm/150mm, the total length is 139mm. The MTF of the two fields are ?0.5@16lp/mm at -45°C?+60°C, which shows its optical performance approximates to the diffraction limit.

  13. MTI Focal Plane Assembly Design and Performance

    SciTech Connect

    Ballard, M.; Rienstra, J.L.

    1999-06-17

    The focal plane assembly for the Multispectral Thermal Imager (MTI) consists of sensor chip assemblies, optical filters, and a vacuum enclosure. Sensor chip assemblies, composed of linear detector arrays and readout integrated circuits, provide spatial resolution in the cross-track direction for the pushbroom imager. Optical filters define 15 spectral bands in a range from 0.45 {micro}m to 10.7 {micro}m. All the detector arrays are mounted on a single focal plane and are designed to operate at 75 K. Three pairs of sensor chip assemblies (SCAs) are required to provide cross-track coverage in all 15 spectral bands. Each pair of SCAs includes detector arrays made from silicon, iridium antimonide, and mercury cadmium telluride. Read out integrated circuits multiplex the signals from the detectors to 18 separate video channels. Optical filter assemblies defining the spectral bands are mounted over the linear detector arrays. Each filter assembly consists of several filter strips bonded together side-by-side. The MTI focal plane assembly has been integrated with the rest of the payload and has undergone detailed testing and calibration. This paper includes representative test data for the various spectral bands and the overall performance of the focal plane assembly.

  14. Focal Plane Instrumentation of VERITAS

    E-print Network

    VERITAS Collaboration; T. Nagai; R. McKay; G. Sleege; D. Petry

    2007-09-28

    VERITAS is a new atmospheric Cherenkov imaging telescope array to detect very high energy gamma rays above 100 GeV. The array is located in southern Arizona, USA, at an altitude of 1268m above sea level. The array consists of four 12-m telescopes of Davies-Cotton design and structurally resembling the Whipple 10-m telescope. The four focal plane instruments are equipped with high-resolution (499 pixels) fast photo-multiplier-tube (PMT) cameras covering a 3.5 degree field of view with 0.15 degree pixel separation. Light concentrators reduce the dead-space between PMTs to 25% and shield the PMTs from ambient light. The PMTs are connected to high-speed preamplifiers allowing operation at modest anode current and giving good single photoelectron peaks in situ. Electronics in the focus box provides real-time monitoring of the anode currents for each pixel and ambient environmental conditions. A charge injection subsystem installed in the focus box allows daytime testing of the trigger and data acquisition system by injecting pulses of variable amplitude and length directly into the photomultiplier preamplifiers. A brief description of the full VERITAS focal plane instrument is given in this paper.

  15. Solid-state curved focal plane arrays

    NASA Technical Reports Server (NTRS)

    Nikzad, Shouleh (Inventor); Hoenk, Michael (Inventor); Jones, Todd (Inventor)

    2010-01-01

    The present invention relates to curved focal plane arrays. More specifically, the present invention relates to a system and method for making solid-state curved focal plane arrays from standard and high-purity devices that may be matched to a given optical system. There are two ways to make a curved focal plane arrays starting with the fully fabricated device. One way, is to thin the device and conform it to a curvature. A second way, is to back-illuminate a thick device without making a thinned membrane. The thick device is a special class of devices; for example devices fabricated with high purity silicon. One surface of the device (the non VLSI fabricated surface, also referred to as the back surface) can be polished to form a curved surface.

  16. SNAP focal plane

    SciTech Connect

    Lampton, Michael L.; Kim, A.; Akerlof, C.W.; Aldering, G.; Amanullah, R.; Astier, P.; Barrelet, E.; Bebek, C.; Bergstrom, L.; Berkovitz, J.; Bernstein, G.; Bester, M.; Bonissent, A.; Bower, C.; Carithers Jr., W.C.; Commins, E.D.; Day, C.; Deustua, S.E.; DiGennaro,R.; Ealet, A.; Ellis, R.S.; Eriksson, M.; Fruchter, A.; Genat, J.-F.; Goldhaber, G.; Goobar, A.; Groom, D.; Harris, S.E.; Harvey, P.R.; Heetderks, H.D.; Holland, S.E.; Huterer, D.; Karcher, A.; Kolbe, W.; Krieger, B.; Lafever, R.; Lamoureux, J.; Levi, M.E.; Levin, D.S.; Linder,E.V.; Loken, S.C.; Malina, R.; Massey, R.; McKay, T.; McKee, S.P.; Miquel, R.; Mortsell, E.; Mostek, N.; Mufson, S.; Musser, J.; Nugent, P.; Oluseyi, H.; Pain, R.; Palaio, N.; Pankow, D.; Perlmutter, S.; Pratt, R.; Prieto, E.; Refregier, A.; Rhodes, J.; Robinson, K.; Roe, N.; Sholl, M.; Schubnell, M.; Smadja, G.; Smoot, G.; Spadafora, A.; Tarle, G.; Tomasch,A.; von der Lippe, H.; Vincent, R.; Walder, J.-P.; Wang, G.

    2002-07-29

    The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square-degree field sensitive in the visible and near-infrared wavelength regime. We describe the requirements for the instrument suite and the evolution of the focal plane design to the present concept in which all the instrumentation--visible and near-infrared imagers, spectrograph, and star guiders--share one common focal plane.

  17. Focal Plane Metrology for the LSST Camera

    SciTech Connect

    A Rasmussen, Andrew P.; Hale, Layton; Kim, Peter; Lee, Eric; Perl, Martin; Schindler, Rafe; Takacs, Peter; Thurston, Timothy; /SLAC

    2007-01-10

    Meeting the science goals for the Large Synoptic Survey Telescope (LSST) translates into a demanding set of imaging performance requirements for the optical system over a wide (3.5{sup o}) field of view. In turn, meeting those imaging requirements necessitates maintaining precise control of the focal plane surface (10 {micro}m P-V) over the entire field of view (640 mm diameter) at the operating temperature (T {approx} -100 C) and over the operational elevation angle range. We briefly describe the hierarchical design approach for the LSST Camera focal plane and the baseline design for assembling the flat focal plane at room temperature. Preliminary results of gravity load and thermal distortion calculations are provided, and early metrological verification of candidate materials under cold thermal conditions are presented. A detailed, generalized method for stitching together sparse metrology data originating from differential, non-contact metrological data acquisition spanning multiple (non-continuous) sensor surfaces making up the focal plane, is described and demonstrated. Finally, we describe some in situ alignment verification alternatives, some of which may be integrated into the camera's focal plane.

  18. Focal Cortical Atrophy Syndromes

    Microsoft Academic Search

    Sandra E. Black

    1996-01-01

    The topography of Alzheimer's disease (AD) and its effects on language, perception, and praxis are briefly reviewed as background to the focal cortical atrophy syndromes, including primary progressive aphasia (PPA), posterior cortical atrophy (PCA), and corticobasal degeneration (CBD). Simplistically speaking, there are two main pathological and neuroimaging phenotypes associated with these syndromes. One is frontotemporal degeneration (FTD), a nonspecific spongiform

  19. Progress in focal plane array technologies

    NASA Astrophysics Data System (ADS)

    Rogalski, Antoni

    2012-03-01

    Development of focal plane arrays started in seventies last century and has revolutionized imaging systems in the next decades. This paper presents progress in optical detector technology of focal plane arrays during the past twenty years. At the beginning of paper, emphasises are given on integrated detector assembly and cooling requirements of different types of detectors. Next, the classification of two types of detectors (photon detectors and thermal detectors) is done on the basis of their principle of operation. This topic is followed by general overview of focal plane array architectures. The main subject of paper is concentrated on describing of material systems and detectors operated in different spectral ranges. Special attention is given on recent progress in their detector technologies. Discussion is focused mainly on current and the most rapidly developing focal plane arrays including: CdZnTe detectors, AlGaN photodiodes, visible CCD and CMOS imaging systems, HgCdTe heterostructure photodiodes, quantum well AlGaAs/GaAs photoresistors, and thermal detectors. Emphasis is also given on far-infrared and sub-millimetre wave detector arrays. Finally, the outlook for near-future trends in optical detector technologies is presented.

  20. Macular Pigment Optical Density and Ocular Pulse Amplitude in Subjects with Different Axial Lengths and Refractive Errors

    PubMed Central

    Czepita, Maciej; Karczewicz, Danuta; Safranow, Krzysztof; Czepita, Damian

    2015-01-01

    Background The purpose of our study was to: (1) investigate the macular pigment optical density (MPOD) and ocular pulse amplitude (OPA) in subjects with different axial lengths (AL) and refractive errors (RE); (2) determine if there is a correlation between MPOD and OPA; and (3) evaluate whether MPOD and OPA depend on intraocular pressure (IOP). Material/Methods This study included 140 eyes of 70 subjects – 17 men and 53 women, aged 18 to 29 years (mean: 22.5 years; SD=2.8). Every examined person underwent a thorough eye examination including: visual acuity, anterior segment and fundus examination, keratometry, auto-refractometry, and MPOD, OPA, AL, and IOP measurements. The obtained results were analyzed statistically using Statistica 10 software. P values of <0.05 were considered statistically significant. Results The following refractive errors were selected: emmetropia (34 eyes), hyperopia (18 eyes), low myopia (60 eyes), medium myopia (19 eyes), and high myopia (9 eyes). It has been established that the OPA increases with the rise in the spherical equivalents (SE) (Rs=+0.38, P<0.001), while the increase in AL correlates with the decrease of OPA (Rs=–0.40, P<0.001). The increase in IOP correlates with the rise in the OPA (Rs=+0.20, P<0.05). There were no significant correlations between IOP and SE or AL. Conclusions (1) MPOD is not correlated with the OPA in subjects with different AL and RE; (2) OPA decreases with the rise of AL; (3) OPA decreases with the fall of the SE; and (4) OPA increases with the rise in IOP. PMID:26071973

  1. Macular Pigment Optical Density and Ocular Pulse Amplitude in Subjects with Different Axial Lengths and Refractive Errors.

    PubMed

    Czepita, Maciej; Karczewicz, Danuta; Safranow, Krzysztof; Czepita, Damian

    2015-01-01

    BACKGROUND The purpose of our study was to: (1) investigate the macular pigment optical density (MPOD) and ocular pulse amplitude (OPA) in subjects with different axial lengths (AL) and refractive errors (RE); (2) determine if there is a correlation between MPOD and OPA; and (3) evaluate whether MPOD and OPA depend on intraocular pressure (IOP). MATERIAL AND METHODS This study included 140 eyes of 70 subjects - 17 men and 53 women, aged 18 to 29 years (mean: 22.5 years; SD=2.8). Every examined person underwent a thorough eye examination including: visual acuity, anterior segment and fundus examination, keratometry, auto-refractometry, and MPOD, OPA, AL, and IOP measurements. The obtained results were analyzed statistically using Statistica 10 software. P values of <0.05 were considered statistically significant. RESULTS The following refractive errors were selected: emmetropia (34 eyes), hyperopia (18 eyes), low myopia (60 eyes), medium myopia (19 eyes), and high myopia (9 eyes). It has been established that the OPA increases with the rise in the spherical equivalents (SE) (Rs=+0.38, P<0.001), while the increase in AL correlates with the decrease of OPA (Rs=-0.40, P<0.001). The increase in IOP correlates with the rise in the OPA (Rs=+0.20, P<0.05). There were no significant correlations between IOP and SE or AL. CONCLUSIONS (1) MPOD is not correlated with the OPA in subjects with different AL and RE; (2) OPA decreases with the rise of AL; (3) OPA decreases with the fall of the SE; and (4) OPA increases with the rise in IOP. PMID:26071973

  2. Dense Pattern Optical Multipass Cell

    NASA Technical Reports Server (NTRS)

    Silver, Joel A. (Inventor)

    2009-01-01

    A multiple pass optical cell and method comprising providing a pair of opposed cylindrical mirrors having curved axes with substantially equal focal lengths, positioning an entrance hole for introducing light into the cell and an exit hole for extracting light from the cell, wherein the entrance hole and exit hole are coextensive or non-coextensive, introducing light into the cell through the entrance hole, and extracting light from the cell through the exit hole.

  3. Gas spectroscopy and optical path-length assessment in scattering media using a frequency-modulated continuous-wave diode laser.

    PubMed

    Mei, Liang; Jayaweera, Hiran; Lundin, Patrik; Svanberg, Sune; Somesfalean, Gabriel

    2011-08-15

    Simultaneous assessment of the spectroscopic absorption signal of gas enclosed in a scattering medium and the corresponding optical path length of the probing light is demonstrated using a single setup. Sensitive gas absorption measurements are performed by a tunable diode laser using wavelength-modulation spectroscopy, while the path length is evaluated by the frequency-modulated cw technique commonly used in the field of telecommunication. Proof-of-principle measurements are demonstrated with water vapor as the absorbing gas and using polystyrene foam as an inhomogeneously scattering medium. The combination of these techniques opens up new possibilities for straightforward evaluation of gas presence and exchange in scattering media. PMID:21847151

  4. SNAP focal plane

    Microsoft Academic Search

    Michael L. Lampton; Christopher Bebek; Carl W. Akerlof; Greg Aldering; R. Amanullah; Pierre Astier; E. Barrelet; Lars Bergstrom; John Bercovitz; Gary M. Bernstein; Manfred Bester; Alain Bonissent; C. R. Bower; William C. Carithers Jr.; Eugene D. Commins; C. Day; Susana E. Deustua; Richard S. DiGennaro; Anne Ealet; Richard S. Ellis; Mikael Eriksson; Andrew Fruchter; Jean-Francois Genat; Gerson Goldhaber; Ariel Goobar; Donald E. Groom; Stewart E. Harris; Peter R. Harvey; Henry D. Heetderks; Steven E. Holland; Dragan Huterer; Armin Karcher; Alex G. Kim; William F. Kolbe; B. Krieger; R. Lafever; J. Lamoureux; Michael E. Levi; Daniel S. Levin; Eric V. Linder; Stewart C. Loken; Roger Malina; R. Massey; Timothy McKay; Steven M. McKee; Ramon Miquel; E. Moertsell; N. Mostek; Stuart Mufson; J. A. Musser; Peter E. Nugent; Hakeem M. Oluseyi; Reynald Pain; Nicholas P. Palaio; David H. Pankow; Saul Perlmutter; R. Pratt; Eric Prieto; Alexandre Refregier; J. Rhodes; Kem E. Robinson; N. Roe; Michael Sholl; Michael S. Schubnell; G. Smadja; George F. Smoot; Anthony Spadafora; Gregory Tarle; Andrew D. Tomasch; H. von der Lippe; D. Vincent; J.-P. Walder; Guobin Wang

    2003-01-01

    The proposed SuperNova\\/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square-degree field sensitive in the visible and near-infrared wavelength regime. We describe the requirements for the instrument suite and the evolution of the focal plane design to the present concept in which all the instrumentation -- visible and near-infrared imagers, spectrograph,

  5. Focal Plane Metrology for the LSST Camera

    Microsoft Academic Search

    Andrew P. A Rasmussen; Layton Hale; Peter Kim; Eric Lee; Martin Perl; Rafe Schindler; Peter Takacs; Timothy Thurston

    2007-01-01

    Meeting the science goals for the Large Synoptic Survey Telescope (LSST) translates into a demanding set of imaging performance requirements for the optical system over a wide (3.5{sup o}) field of view. In turn, meeting those imaging requirements necessitates maintaining precise control of the focal plane surface (10 μm P-V) over the entire field of view (640 mm diameter) at

  6. Towards dualband megapixel QWIP focal plane arrays

    Microsoft Academic Search

    S. D. Gunapala; S. V. Bandara; J. K. Liu; J. M. Mumolo; C. J. Hill; S. B. Rafol; D. Salazar; J. Woolaway; P. D. LeVan; M. Z. Tidrow

    2007-01-01

    Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024×1024 pixel quantum well infrared photodetector (QWIP) focal planes have been demonstrated with excellent imaging performance. The MWIR QWIP detector array has demonstrated a noise equivalent differential temperature (NE?T) of 17mK at a 95K operating temperature with f\\/2.5 optics at 300K background and the LWIR detector array has demonstrated a NE?T of 13mK

  7. Introduction into service of mature pushbroom electro-optic sensors

    NASA Astrophysics Data System (ADS)

    Brownie, Ralph S.

    2000-11-01

    Pushbroom Electro-Optic sensors have been developed and brought into full production, entering service in year 2000 on RAF Jaguar and Belgian Air Force F-16. The use of fiber- optic gyroscopes, closely coupled to the focal plane electronics, permits correction of all motion effects and provides practical high quality, stereo imagery at high V/H ratios. This paper describes technical features and samples of imagery from a scalable range of sensors incorporating focal lengths from 38mm to 900mm and operating throughout the full flight envelope of modern fighter aircraft.

  8. Electro-Optical Characteristics of P+n In0.53Ga0.47As Hetero-Junction Photodiodes in Large Format Dense Focal Plane Arrays

    NASA Astrophysics Data System (ADS)

    DeWames, R.; Littleton, R.; Witte, K.; Wichman, A.; Bellotti, E.; Pellegrino, J.

    2015-03-01

    This paper is concerned with focal plane array (FPA) data and use of analytical and three-dimensional numerical simulation methods to determine the physical effects and processes limiting performance. For shallow homojunction P+n designs the temperature dependence of dark current for T < 300 K depends on the intrinsic carrier concentration of the In0.53Ga0.47As material, implying that the dominant dark currents are generation and recombination (G-R) currents originating in the depletion regions of the double layer planar heterostructure (DLPH) photodiode. In the analytical model differences from bulk G-R behavior are modeled with a G-R like perimeter-dependent shunt current conjectured to originate at the InP/InGaAs interface. In this description the fitting property is the effective conductivity, ? eff(T), in mho cm-1. Variation in the data suggests ? eff (300 K) values of 1.2 × 10-11-4.6 × 10-11 mho cm-1). Substrate removal extends the quantum efficiency (QE) spectral band into the visible region. However, dead-layer effects limit the QE to 10% at a wavelength of 0.5 ?m. For starlight-no moon illumination conditions, the signal-to-noise ratio is estimated to be 50 at an operating temperature of 300 K. A major result of the 3D numerical simulation of the device is the prediction of a perimeter G-R current not associated with the properties of the metallurgical interface. Another is the prediction that for a junction positioned in the larger band gap InP cap layer the QE is bias-dependent and that a relatively large reverse bias ?0.9 V is needed for the QE to saturate to the shallow homojunction value. At this higher bias the dark current is larger than the shallow homojunction value. The 3D numerical model and the analytical model agree in predicting and explaining the measured radiatively limited diffusion current originating at the n-side of the junction. The calculations of the area-dependent G-R current for the condition studied are also in agreement. Unique advantages of the 3D numerical simulation are the ability to mimic real device structures, achieve deeper understanding of the real physical effects associated with the various methods of junction formation, and predict how device designs will function.

  9. Oral focal epithelial hyperplasia.

    PubMed

    López-Jornet, Pía; Camacho-Alonso, Fabio; Berdugo, Lucero

    2010-01-01

    Focal epithelial hyperplasia (FEH) is a benign, asymptomatic disease. It appears as papules, principally on the lower lip, although it can also be found on the retro-commissural mucosa and tongue and, less frequently, on the upper lip, gingiva and palate. FEH is caused by human papillomavirus subtype 13 or 32. The condition occurs in many populations and ethnic groups. We present the clinical case of a 31-year-old male with lesions that clinically and histologically corresponded to FEH. PMID:20863043

  10. Development of high-performance optical system for small satellites

    Microsoft Academic Search

    Young-Wan Choi; Seung-Uk Yang; Myung-Seok Kang; Ee-Eul Kim

    2007-01-01

    Funded by the Ministry of Commerce, Industry, and Energy of Korea, Satrec Initiative has initiated the development of the prototype model of a TMA-based electro-optical system as part of the national space research and development program. Its optical aperture diameter is 120 mm, the effective focal length is 462 mm, and its full field-of-view is 5.08 degrees. The dimension is

  11. Focal Cryotherapy for Prostate Cancer

    Microsoft Academic Search

    Matvey Tsivian; Thomas J. Polascik

    2010-01-01

    Focal therapy for prostate cancer has emerged an interesting concept as a less morbid option for the treatment of localized\\u000a low-risk disease. Despite the growing interest in focal therapy, this approach has not yet gained sufficient popularity nor\\u000a provided enough data to be discussed outside the experimental application. Herein we summarize the available data on focal\\u000a cryotherapy and focus on

  12. Oral focal mucinosis: case report

    PubMed Central

    GERMANO, F.; ABATE, R.; SANTINI, F.; DRI, M.; ARCURI, C.

    2009-01-01

    SUMMARY Oral focal mucinosis (OFM) is an uncommon disease of unknown aetiology. It is considered to be the oral counterpart of cutaneous focal mucinosis and cutaneous myxoid cyst and it is characterized by a focal myxoid degeneration of the connective tissue. A preoperative diagnosis is almost impossible, and the clinical suspicion, usually made by exclusion, must be confirmed by a bioptic examination followed by histological observations. The Authors report a case of focal oral mucinosis diagnosed and treated in a male adult patient. PMID:23285343

  13. Measuring Length

    NSDL National Science Digital Library

    This article focuses on young students encountering the measurement of length. The article cites examples of key concepts in recognizing length as an attribute and in proper and improper ways to measure length. Conservation and additivity of length, standard and non-standard units, iteration, and the zero point are among the topics presented.

  14. Precision evaluation of lens systems using a nodal slide/MTF optical bench

    NASA Astrophysics Data System (ADS)

    Doherty, Victor J.; Chapnik, Philip D.

    1992-01-01

    A compact, self-contained production instrument designed to permit the rapid and precise performance characterization of a wide variety of lenses and optical systems has been developed by Eidolon Corporation. The Eidolon Production Nodal Slide/MTF Measurement System can be used to measure effective focal length (EFL), distortion, field curvature, chromatic aberration, spot size, and modulation transfer function (MTF).

  15. Simple Method for Fabricating Solid Microlenses With Different Focal Lengths

    Microsoft Academic Search

    Yu Hongbin; Zhou Guangya; Chau Fook Siong; Lee Feiwen

    2008-01-01

    A versatile method of fabricating different microlenses using a relatively simple process is presented. A liquid-filled lens structure integrated with microfluidic network and liquid Polydimethylsiloxane (PDMS) are used as the frame and filling material, respectively, for the injection process. Through simply changing the injection pressure to obtain different membrane deformation profiles followed by curing, the PDMS stuffing together with the

  16. Atom optical shop testing of electrostatic lenses using an atom interferometer

    E-print Network

    Hromada, Ivan; Holmgren, William F; Gregoire, Maxwell D; Cronin, Alexander D

    2013-01-01

    We used an atom interferometer for atom optical shop testing of lenses for atomic de Broglie waves. We measured focal lengths and spherical aberrations of electrostatic lenses in three independent ways based on contrast data, phase data, or calculations of de Broglie wavefront curvature. We report focal lengths of -2.5 km and -21.7 km with 5% uncertainty for different lenses. All three methods give consistent results. Understanding how lenses magnify and distort atom interference fringes helps improve atom beam velocity measurements made with phase choppers [New J. Phys. 13, 115007 (2011)], which in turn will improve the accuracy of atomic polarizability measurements.

  17. Optical beam focusing by a single subwavelength metal slit surrounded by chirped dielectric surface gratings

    SciTech Connect

    Kim, Seyoon; Lim, Yongjun; Kim, Hwi; Park, Junghyun; Lee, Byoungho [National Creative Research Center for Active Plasmonics Application Systems, Inter-University Semiconductor Research Center and School of Electrical Engineering, Seoul National University, Gwanak-Gu Sillim-Dong, Seoul 151-774 (Korea, Republic of)

    2008-01-07

    A method for optical beam focusing by a single subwavelength metal slit surrounded by surface gratings is proposed. In our proposed method, the period of each surface grating is chirped so that the radiation fields of surface plasmon polaritons can be controlled to make a beam spot at the desired focal length. Through our proposed method, it is numerically shown that we can make a beam spot which is located at the several times of wavelength distance from the slit, and its focal length can be controlled.

  18. Switchable Fresnel zone lenses for optical interconnections

    Microsoft Academic Search

    Margit Ferstl; Anna-Maria Frisch

    1996-01-01

    Various on-axis and off-axis Fresnel zone lenses with different focal lengths and of different apertures were fabricated in quartz glass by means of microstructuring techniques. The kinoform profile of the diffractive optical elements was approximated by a staircase-like profile having a number of discrete phase levels. Dynamic, that is electrically switchable, lenses have been realized by filling the structured surface

  19. Experimental validation of Monte Carlo and finite-element methods for the estimation of the optical path length in inhomogeneous tissue

    NASA Astrophysics Data System (ADS)

    Okada, Eiji; Schweiger, Martin; Arridge, Simon R.; Firbank, Michael; Delpy, David T.

    1996-07-01

    To validate models of light propagation in biological tissue, experiments to measure the mean time of flight have been carried out on several solid cylindrical layered phantoms. The optical properties of the inner cylinders of the phantoms were close to those of adult brain white matter, whereas a range of scattering or absorption coefficients was chosen for the outer layer. Experimental results for the mean optical path length have been compared with the predictions of both an exact Monte Carlo (MC) model and a diffusion equation, with two differing boundary conditions implemented in a finite-element method (FEM). The MC and experimental results are in good agreement despite poor statistics for large fiber spacings, whereas good agreement with the FEM prediction requires a careful choice of proper boundary conditions. measurement, Monte Carlo method, finite-element method.

  20. Range formulation for a staring electro-optical and imaging system incorporating the effects of atmospheric transmission, focal plane 1/f noise and fixed pattern noise

    NASA Astrophysics Data System (ADS)

    Dhar, Vikram; Khan, Zafar; Lomash, S. K.; Chhabra, K. C.

    1995-12-01

    To increase the detection range in staring FPAs, commonly the integration time Ti is increased, as the range is assumed to increase as one-fourth power of Ti, (T1/(4)i). It is shown here that the range dependence on Ti is weaker thanT1/(4)i , because of the effect of atmosphere. Since the atmospheric transmission coefficient decreases with increasing range, the effect of increasing Ti on the range is considerably reduced. It is also shown that when detector 1/f noise dominates over other noise sources, the dependence of range on Ti is much weaker thanT1/(4)i , having a logarithmic dependence. Calculations have been done by integrating equations involving spectral functions-photon flux, atmospheric transmission coefficient, optics transmission coefficient and responsivity-over wavelength, in the spectral range from 8 ?m to 12 ?m. LOWTRAN2 has been used for spectral atmospheric transmission coefficients, for different conditions of ambient temperature (-30°C to 55°C) and relative humidity (50-85%). The range formulation also distinguishes between distant targets (point sources) and nearby targets (extended sources). The analysis is applicable for terrestrial imaging, where the temperature difference of the target and the background is small. The effect of fixed pattern noise (FPN) in mercury cadmium telluride (MCT) FPAs has also been considered by modeling FPN in terms of a composition variation in the MCT. It is seen that range, both in the point source and the extended source cases, is not a sensitive function of FPN.

  1. Intelligent Optical Systems Using Adaptive Optics

    NASA Technical Reports Server (NTRS)

    Clark, Natalie

    2012-01-01

    Until recently, the phrase adaptive optics generally conjured images of large deformable mirrors being integrated into telescopes to compensate for atmospheric turbulence. However, the development of smaller, cheaper devices has sparked interest for other aerospace and commercial applications. Variable focal length lenses, liquid crystal spatial light modulators, tunable filters, phase compensators, polarization compensation, and deformable mirrors are becoming increasingly useful for other imaging applications including guidance navigation and control (GNC), coronagraphs, foveated imaging, situational awareness, autonomous rendezvous and docking, non-mechanical zoom, phase diversity, and enhanced multi-spectral imaging. The active components presented here allow flexibility in the optical design, increasing performance. In addition, the intelligent optical systems presented offer advantages in size and weight and radiation tolerance.

  2. Statistical earthquake focal mechanism forecasts

    E-print Network

    Kagan, Yan Y

    2013-01-01

    Forecasts of the focal mechanisms of future earthquakes are important for seismic hazard estimates and Coulomb stress and other models of earthquake occurrence. Here we report on a high-resolution global forecast of earthquake rate density as a function of location, magnitude, and focal mechanism. In previous publications we reported forecasts of 0.5 degree spatial resolution, covering the latitude range magnitude, and focal mechanism. In previous publications we reported forecasts of 0.5 degree spatial resolution, covering the latitude range from -75 to +75 degrees, based on the Global Central Moment Tensor earthquake catalog. In the new forecasts we've improved the spatial resolution to 0.1 degree and the latitude range from pole to pole. Our focal mechanism estimates require distance-weighted combinations of observed focal mechanisms within 1000 km of each grid point. Simultaneously we calculate an average rotation angle between the forecasted mechanism and all the surrounding mechanisms, using the method ...

  3. Analysis of sensitivity and optical path-length in non-invasive measurement of glucose with near infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Luo, Yunhan; Liu, Rong; Chen, Wenliang; Cui, Houxin; Xu, Kexin

    2005-03-01

    Non-invasive glucose monitoring with optical methods has obtained increasing interest, in that the methods have shown great benefit for diabetes. Nevertheless, low sensitivity and signal to noise ratio (ratio of effective photons) are two major difficulties in non-invasively NIR spectral monitoring of blood glucose concentration. Designing the optical probe properly is one of the effective ways to improve measuring sensitivity and ratio of effective photons. In this paper, definition about ratio of effective photons in measurement of glucose is introduced. And then effect of glucose on optical properties of human skin is analyzed, based on this, two kind of sensitivities for diffuse reflectance, namely sensitivity to absorption and that to scattering, is derived. To investigate the ratio of effective photons and sensitivities, Monte Carlo simulations have been performed on a three-layered media with optical parameters similar to those of human skin. The results have shown that (1) high ratio of effective photons, even as high as 60%, can be obtained by choosing proper the separation between source and detector; (2) sensitivity of diffuse reflectance to absorption and scattering has different dependence on source-detector separation, which enables one can have different options by making use of different effect from glucose level changing. In the end, some suggestions have been put forward to improve precision of measurement of blood glucose.

  4. Electro-optically actuated liquid-lens zoom

    NASA Astrophysics Data System (ADS)

    Pütsch, O.; Loosen, P.

    2012-06-01

    Progressive miniaturization and mass market orientation denote a challenge to the design of dynamic optical systems such as zoom-lenses. Two working principles can be identified: mechanical actuation and application of active optical components. Mechanical actuation changes the focal length of a zoom-lens system by varying the axial positions of optical elements. These systems are limited in speed and often require complex coupled movements. However, well established optical design approaches can be applied. In contrast, active optical components change their optical properties by varying their physical structure by means of applying external electric signals. An example are liquidlenses which vary their curvatures to change the refractive power. Zoom-lenses benefit from active optical components in two ways: first, no moveable structures are required and second, fast response characteristics can be realized. The precommercial development of zoom-lenses demands simplified and cost-effective system designs. However the number of efficient optical designs for electro-optically actuated zoom-lenses is limited. In this paper, the systematic development of an electro-optically actuated zoom-lens will be discussed. The application of aberration polynomials enables a better comprehension of the primary monochromatic aberrations at the lens elements during a change in magnification. This enables an enhanced synthesis of the system behavior and leads to a simplified zoom-lens design with no moving elements. The change of focal length is achieved only by varying curvatures of targeted integrated electro-optically actuated lenses.

  5. Derivation of regional aerodynamic roughness length by combining optical remote sensing and ground measurements over agricultural land in Heihe River Basin

    NASA Astrophysics Data System (ADS)

    Chen, Qiting; Jia, Li; Hutjes, Ronald

    2014-11-01

    Information of temporal and spatial variation of aerodynamic roughness length is required in most land surface models. The current research presents a practical approach for determining spatially distributed vegetation aerodynamic roughness length with fine temporal and spatial resolution by combining remote sensing and ground measurements. The basic framework of Raupach (1992), with the bulk surface parameters revised by Jasinski et al. (2005) has been applied to optical remote sensing data of HJ-1A/1B missions. In addition, a method for estimating regional scale vegetation height was introduced, so the aerodynamic roughness length, which is more preferred by users than the height normalized form has been developed. Direct validation on different vegetation classes have finally been performed taking advantage of the data-dense field experiments of Heihe Watershed Allied Telemetry Experimental Research (HiWATER). The roughness model had an overall good performance on most of Eddy Covariance sites of HiWATER. However, deviations still existed on different sites, and these have been further analyzed.

  6. Robust focusing optics for high-power laser welding

    NASA Astrophysics Data System (ADS)

    McAllister, Blake

    2014-02-01

    As available power levels from both fiber and disc lasers rapidly increase, so does the need for more robust beam delivery solutions. Traditional transmissive optics for 1 micron lasers have proven to be problematic in the presence of higher power densities and are more susceptible to focal shift. A new, fully-reflective, optical solution has been developed using mirrors rather than lenses and windows to achieve the required stable focal spot, while still protecting the delicate fiber end. This patent-approved beam focusing solution, referred to as high power reflective focusing optic (HPRFO), involves specialty mirrors and a flowing gas orifice that prevents ingress of contaminants into the optically sensitive region of the assembly. These mirrors also provide a unique solution for increasing the distance between the sensitive optics and the contamination-filled region at the work, without sacrificing spot size. Longer focal lengths and lower power densities on large mass, water-cooled, copper mirrors deliver the robustness needed at increasingly high power levels. The HPRFO exhibits excellent beam quality and minimal focal shift at a fraction of commercially available optics, and has demonstrated consistent reliability on applications requiring 15 kW with prolonged beam-on times.

  7. Focal nodular hyperplasia (FNH).

    PubMed

    Nat, Laura; Poant?, Laura Irina

    2014-01-01

    Focal nodular hyperplasia (FNH) is a benign tumour of the liver (hepatic tumour), which is the second most prevalent tumour of the liver (the first is hepatic hemangioma). It has a higher incidence in females, 20-40 years old, but also occurs in men and even in children. It is usually asymptomatic, rarely grows or bleeds, and has no malignant potential. This tumour was once often resected because it was difficult to distinguish from hepatic adenoma, but with modem multiphase imaging it is now diagnosed strictly by imaging criteria, and not resected. We present the case of a 78 years old man who presented to emergency room (ER) with a history of dry cough, chest pain and mild dyspnea. Chest X-ray showed ascension of the right hemidiaphragm, and a homogeneous round opacity of 6/6.2 cm in the right cardiophrenic angle. The first suspicion was of pulmonary tumor, but the final diagnosis was FNH, confirmed by CT scan. We discuss the differential diagnosis and prognosis of this entity. The particularities of the case are the presentation with respiratory symptoms and pulmonary mass, and the age of the patient. PMID:25000678

  8. Biometric, optical and physical changes in the isolated human crystalline lens with age in relation to presbyopia

    Microsoft Academic Search

    Adrian Glasser; Melanie C. W. Campbell

    1999-01-01

    The biometric, optical and physical properties of 19 pairs of isolated human eye-bank lenses ranging in age from 5 to 96 years were compared. Lens focal length and spherical aberration were measured using a scanning laser apparatus, lens thickness and the lens surface curvatures were measured by digitizing the lens profiles and equivalent refractive indices were calculated for each lens

  9. The Characteristics of Broad and Narrow Focal Zone Lithotripters

    NASA Astrophysics Data System (ADS)

    Pishchalnikov, Yuri A.; McAteer, James A.; VonDerHaar, R. Jason; Pishchalnikova, Irina V.; Williams, James C.

    2008-09-01

    The focal width of a lithotripter is a measure of the diameter of its focal zone, the region where acoustic pressures are at least half the maximum positive pressure generated at a given power level. Different lithotripters have different focal widths. The Dornier HM3, for example, has a focal width of ˜10-12 mm and for many years this was the widest focal zone among clinical machines. Electromagnetic lithotripters tend to have narrower focal zones, in the range of ˜4-6 mm. Recent studies suggesting that focal width plays an important role in stone breakage prompted this assessment of two electromagnetic lithotripters. Acoustical mapping using a fiber optic probe hydrophone (FOPH-500) and breakage of U-30 gypsum model stones were used to compare a conventional lithotripter (Dornier DoLi-50) and a broad focal zone device (XiXin XX-ES). FOPH mapping characterized the focal width of the DoLi to be about 5mm and that of the XX-ES to be much wider (˜18 mm). For stone breakage experiments the DoLi was fired at power level 3 (mid-range) and the XX-ES was operated at the recommended clinical setting of 9.3 kV. Both lithotripters were fired at 60 SW/min. U-30 model stones held in a 2mm mesh basket were positioned at the clinical target point on the acoustic axis and at 5mm steps laterally, and the number of SW's to complete fragmentation was counted. Breakage on-axis was similar for the two machines (DoLi 676±105 SW's versus XX-ES 644±123 SW's, p>0.6), but at 15mm the DoLi required nearly twice the number of SW's as the XX-ES (DoLi 3006±780 SW's versus 1726±972 SW's, p<0.006). This demonstrates that a broad focal zone lithotripter is more effective in breaking stones off axis and supports the idea that focal width is an important feature, likely to be relevant in the clinical setting where respiratory motion may limit the effectiveness of narrow focal zone machines.

  10. Focal cortical atrophy syndromes.

    PubMed

    Black, S E

    1996-07-01

    The topography of Alzheimer's disease (AD) and its effects on language, perception, and praxis are briefly reviewed as background to the focal cortical atrophy syndromes, including primary progressive aphasia (PPA), posterior cortical atrophy (PCA), and corticobasal degeneration (CBD). Simplistically speaking, there are two main pathological and neuroimaging phenotypes associated with these syndromes. One is frontotemporal degeneration (FTD), a nonspecific spongiform degeneration, with gliosis and neuronal loss, sometimes with Pick cells and bodies, which is usually selective for frontal and anterior temporal cortex. The other is Alzheimer's disease, in which amyloid plaques and neurofibrillary tangles initially develop in the hippocampal region, and spread to the lateral temporal and parietal neocortex and then to the frontal cortex. In the case of PPA, left perisylvian dysfunction is usually evident at presentation clinically and on neuroimaging. Nonfluent progressive aphasia tends to progress anteriorly and is usually associated with FTD. In fluent progressive aphasia, the pathology may progress anteriorly due to FTD or posteriorly, reflecting AD. In PCA, the visual association cortex is targeted bilaterally, often more so on the right, and the pathology is usually indicative of AD. CBD is an asymmetric akinetic-rigid syndrome associated with apraxia, in which swollen achromatic neurons are present in the frontoparietal cortex and substantia nigra on light microscopy, suggesting to some that it may fall within the spectrum of FTD and Pick's disease. The application of new molecular biological techniques, however, suggest that CBD, FTD, and Pick's Disease may be pathologically distinct. The clinico-pathological features of each syndrome are reviewed and compared to those typical for AD, and single photon emission computerized tomography scans representative for each are illustrated. PMID:8811996

  11. A 15 element focal plane array for 100 GHz

    Microsoft Academic Search

    Neal R. Erickson; Paul F. Goldsmith; G. Novak; Ronald M. Grosslein; P. J. Viscuso; Ronna B. Erickson; C. R. Predmore

    1992-01-01

    A focal plane imaging array receiver is described which covers the 86-115 GHz frequency range for radio astronomical observations. The 3 x 5 element array uses cryogenic Schottky diode mixers with integrated HEMT IF amplifiers. A cold quasi-optical filter selects the desired sideband, and terminates the image at 20 K. Polarization interleaving is used to minimize the array size on

  12. Determination of the refractive index of highly scattering human tissue by optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Tearney, G. J.; Brezinski, M. E.; Southern, J. F.; Bouma, B. E.; Hee, M. R.; Fujimoto, J. G.

    1995-11-01

    We describe two new techniques, based on optical coherence tomography (OCT), for determining the refractive index of highly scattering human tissue. We obtained refractive indices of in vitro human tissue, using OCT to measure the physical and optical path lengths of the sample. We obtained measurements of the refractive index of in vitro and in vivo human tissue, using OCT to track the focal length shift that results from translating the focus along the optic axis within the tissue. The refractive indices of human skin, adipose, and muscle were measured and compared with previously published estimates.

  13. Long wavelength infrared dual field-of-view optical system

    NASA Astrophysics Data System (ADS)

    Xiong, Tao; Yang, Chang-cheng

    2007-12-01

    For cooled 320×240 staring focal plane array (FPA), a novel long wavelength infrared dual field-of-view optical system is presented in the paper. The optical system is composed of re-imaging part and zooming part. The parameters of the system are 1.96 f/number, 100% cold shield efficiency, 180mm/60mm effective focal length (EFL) and 8-10 ?m spectrum region. The optical system is analyzed from two modes of narrow field of view (NFOV) and wide field of view (WFOV). The system can be used in the temperature range from-30°Cand 60°C without significant degradation of optical performance. The final test results prove the designed performance is good..

  14. Ladybug Lengths

    NSDL National Science Digital Library

    2012-01-01

    This lesson introduces students to the measurable attribute of length and provides practice in measuring length using non-standard units. The lesson is launched using the story Ladybug on the Move by Richard Fowler. Lesson objectives, teaching ideas, and handouts are included.

  15. Curved focal plane detector array for wide field cameras.

    PubMed

    Dumas, Delphine; Fendler, Manuel; Baier, Nicolas; Primot, Jérôme; le Coarer, Etienne

    2012-08-01

    Miniaturization is the main goal for system design in future cameras. This paper offers a novel method to scale down the optical system and to improve the image quality. As with the human retina, the detector array is spherically bent to fit the curved image surface; so the field curvature aberration is directly suppressed, leading to a better resolution and a simplified optical design. By thinning the substrate, the device is monolithically curved without modifying the fabrication process of the active pixels. Optical characterizations have been performed on planar and curved focal plane based cameras to illustrate the optical advantages of detector array curvature. PMID:22859030

  16. High resolution wavefront measurement of aspheric optics

    NASA Astrophysics Data System (ADS)

    Erichsen, I.; Krey, S.; Heinisch, J.; Ruprecht, A.; Dumitrescu, E.

    2008-08-01

    With the recently emerged large volume production of miniature aspheric lenses for a wide range of applications, a new fast fully automatic high resolution wavefront measurement instrument has been developed. The Shack-Hartmann based system with reproducibility better than 0.05 waves is able to measure highly aspheric optics and allows for real time comparison with design data. Integrated advanced analysis tools such as calculation of Zernike coefficients, 2D-Modulation Transfer Function (MTF), Point Spread Function (PSF), Strehl-Ratio and the measurement of effective focal length (EFL) as well as flange focal length (FFL) allow for the direct verification of lens properties and can be used in a development as well as in a production environment.

  17. The bolometric focal plane array of the Polarbear CMB experiment

    E-print Network

    Arnold, K; Anthony, A E; Barron, D; Boettger, D; Borrill, J; Chapman, S; Chinone, Y; Dobbs, M A; Errard, J; Fabbian, G; Flanigan, D; Fuller, G; Ghribi, A; Grainger, W; Halverson, N; Hasegawa, M; Hattori, K; Hazumi, M; Holzapfel, W L; Howard, J; Hyland, P; Jaffe, A; Keating, B; Kermish, Z; Kisner, T; Jeune, M Le; Lee, A T; Linder, E; Lungu, M; Matsuda, F; Matsumura, T; Miller, N J; Meng, X; Morii, H; Moyerman, S; Myers, M J; Nishino, H; Paar, H; Quealy, E; Reichardt, C; Richards, P L; Ross, C; Shimizu, A; Shimmin, C; Shimon, M; Sholl, M; Siritanasak, P; Spieler, H; Stebor, N; Steinbach, B; Stompor, R; Suzuki, A; Tomaru, T; Tucker, C; Zahn, O

    2012-01-01

    The Polarbear Cosmic Microwave Background (CMB) polarization experiment is currently observing from the Atacama Desert in Northern Chile. It will characterize the expected B-mode polarization due to gravitational lensing of the CMB, and search for the possible B-mode signature of inflationary gravitational waves. Its 250 mK focal plane detector array consists of 1,274 polarization-sensitive antenna-coupled bolometers, each with an associated lithographed band-defining filter. Each detector's planar antenna structure is coupled to the telescope's optical system through a contacting dielectric lenslet, an architecture unique in current CMB experiments. We present the initial characterization of this focal plane.

  18. Conversion Gain and Interpixel Capacitance of CMOS Hybrid Focal Plane Arrays

    Microsoft Academic Search

    Gert Finger; James W. Beletic; Reinhold Dorn; Manfred Meyer; Leander Mehrgan; Alan Moorwood; Joerg Stegmeier

    2006-01-01

    The conversion gain of optical and infrared focal plane CMOS hybrid arrays is a fundamental parameter, whose value enters into the derivation of other parameters characterizing the performance of a detector. The widespread \\

  19. Focal amyotrophy in neurofibromatosis 2

    PubMed Central

    Trivedi, R.; Byrne, J.; Huson, S.; Donaghy, M.

    2000-01-01

    Neurofibromatosis type 2 (NF2) is an autosomal dominant disorder characterised by bilateral vestibular schwannomas and other CNS tumours including meningiomas and spinal schwannomas. Occasionally, peripheral neuropathy occurs in these patients but this is the first report of focal amyotrophy. Clinical, electrophysiological, and imaging data from four NF2 patients seen at a specialist neurofibromatosis clinic over a 4 year period are described in whom symptomatic focal amyotrophy preceded the diagnosis of NF2. Two presented with wasting and weakness of a single muscle group, several years before NF2 was diagnosed. In one patient a mononeuritis multiplex was the presenting feature of NF2, and in one patient focal wasting and weakness developed after the diagnosis of NF2 was made. In none of the four cases could a focal peripheral nerve or root neurofibroma be identified despite extensive imaging with MRI, and the limitations of neuroimaging for identifying a structural cause in patients with NF2 with a focal peripheral nerve lesion is discussed. It is likely that NF2 may affect peripheral nerve structures in a manner distinct from a compressive schwannoma.?? PMID:10896706

  20. [Focal nodular hyperplasia (author's transl)].

    PubMed

    Schild, H; Thelen, M; Paquet, K J; Biersack, H J; Janson, R; Bücheler, E; Hansen, H H; Grönniger, J

    1980-10-01

    Focal nodular hyperplasia was diagnosed angiographically in 14 patients and confirmed histologically. Differentiation of this benign lesion from other space-occupying diseases of the liver can be very difficult, since focal nodular hyperplasia produces a variable angiographic appearance. The typical angiogram showing radial vessels in the arterial phase and sharply demarcated foci in the parenchyma phase is found in only one third of patients. Angiographic differential diagnosis includes adenomas and carcinomas of the liver. Resection of the tumours in case of malignant tumours is not indicated. Foci at the margin of the liver, or if they are pedunculated, should be removed in case of spontaneous perforation. Tumours in the centre of the liver should be observed (computer tomography). Oral contraceptives stimulate the growth of these foci. They may diminish in size after stopping these drugs. 70% of cases of focal nodular hyperplasia remain clinically silent and were discovered accidentally or at autopsy. PMID:6263766

  1. Payload-envelope detection and label-detection integrated photonic circuit for asynchronous variable-length optical-packet switching with 40-gb\\/s RZ payloads and 10-gb\\/s NRZ labels

    Microsoft Academic Search

    Brian R. Koch; Zhaoyang Hu; John E. Bowers; Daniel J. Blumenthal

    2006-01-01

    A photonic integrated circuit that performs 40-Gb\\/s payload-envelope detection (PED) and 10-Gb\\/s label detection for asynchronous variable-length optical-packet switching is demonstrated. The circuit consists of an InP photonic integrated device combined with electronic GaAs and InP devices on a carrier. Asynchronous variable-length optical packets with 40-Gb\\/s return-to-zero (RZ) payloads and 10-Gb\\/s non-RZ (NRZ) labels are processed by the circuit. The

  2. Adaptive Wavefront-Correction Algorithms Using Focal-Plane Array Intensity Measurements

    NASA Astrophysics Data System (ADS)

    Mukai, R.; Vilnrotter, V. A.; Lau, C.-W.

    2006-08-01

    Earth's atmospheric turbulence induces aberrations in the wavefront of the optical signal from a distant spacecraft. These aberrations cause diffusion and spreading of the signal energy in the receiver's focal plane, potentially resulting in an increase in bit-error rate (BER) by several orders of magnitude when significant background radiation is present, such as during daytime operation. The adaptive optics (AO) algorithms in this article use the focal-plane intensity distribution to estimate aberrations induced by the atmosphere and to correct these aberrations. Successful wavefront correction concentrates the signal energy into a much smaller area in the focal plane, greatly reducing collected background radiation and improving BER performance.

  3. IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS--I: REGULAR PAPERS, VOL. 51, NO. 5, MAY 2004 963 Analog VLSI Focal-Plane Array With

    E-print Network

    Stocker, Alan A.

    VLSI Focal-Plane Array With Dynamic Connections for the Estimation of Piecewise-Smooth Optical Flow location in parallel. Focal-plane implementations of such arrays are constrained by limitations. The circuit architecture of these sensors typically consists of a focal-plane array of independent, isolated

  4. Focal process of the great Chilean earthquake May 22, 1960

    Microsoft Academic Search

    Hiroo Kanamori; John J. Cipar

    1974-01-01

    Long-period strain seismogram recorded at Pasadena is used to determine the focal process of the 1960 Chilean earthquake. Synthetic seismograms computed for various fault models are matched with the observed strain seismogram to determine the fault parameters. A low-angle (~ 10°) thrust model with rupture length of 800 km and rupture velocity of 3.5 km\\/sec is consistent with the observed

  5. Uncooled infrared focal plane arrays

    Microsoft Academic Search

    Paul W. Kruse

    1994-01-01

    Uncooled infrared focal plane arrays have been developed which employ four detection mechanisms: resistive bolometric, pyroelectric, ferroelectric bolometric and thermoelectric. They find application in thermal imaging systems for night vision. Each of the four mechanisms is described. Figures of merit are defined. The fundamental limits to the performance of thermal detectors are presented. The state-of-the-art of the four types of

  6. Determination of carrier lifetime and diffusion length in Al-doped 4H–SiC epilayers by time-resolved optical techniques

    NASA Astrophysics Data System (ADS)

    Liaugaudas, Gediminas; Dargis, Donatas; Kwasnicki, Pawel; Arvinte, Roxana; Zielinski, Marcin; Jaraši?nas, K?stutis

    2015-01-01

    A series of p-type 4H–SiC epilayers with aluminium concentration ranging from 2? × ?1016 to 8? × ?1019?cm?3 were investigated by time-resolved optical techniques in order to determine the effect of aluminium doping on high-injection carrier lifetime at room temperature and the diffusion coefficient at different injections (from ?3? × ?1018 to ?5? × ?1019?cm?3) and temperatures (from 78 to 730?K). We find that the defect limited carrier lifetime ?SRH decreases from 20?ns in the low-doped samples down to ?0.6?ns in the heavily doped epilayers. Accordingly, the ambipolar diffusion coefficient decreases from Da = 3.5?cm2?s?1 down to ?0.6?cm2?s?1, corresponding to the hole mobility of µh = 70?cm2?Vs?1 and 12?cm2?Vs?1, respectively. In the highly doped epilayers, the injection-induced decrease of the diffusion coefficient, due to the transition from the minority carrier diffusion to the ambipolar diffusion, provided the electron diffusion coefficient of De ? 3?cm2?s?1. The Al-doping resulted in the gradual decrease of the ambipolar diffusion length, from LD = 2.7?µm down to LD = 0.25?µm in the epilayers with the lowest and highest aluminium concentrations.

  7. Design and fabrication of continuous-profile diffractive micro-optical elements as a beam splitter.

    PubMed

    Feng, Di; Yan, Yingbai; Jin, Guofan; Fan, Shoushan

    2004-10-10

    An optimization algorithm that combines a rigorous electromagnetic computation model with an effective iterative method is utilized to design diffractive micro-optical elements that exhibit fast convergence and better design quality. The design example is a two-dimensional 1-to-2 beam splitter that can symmetrically generate two focal lines separated by 80 microm at the observation plane with a small angle separation of +/- 16 degrees. Experimental results are presented for an element with continuous profiles fabricated into a monocrystalline silicon substrate that has a width of 160 microm and a focal length of 140 microm at a free-space wavelength of 10.6 microm. PMID:15508604

  8. Enlarged productivity in laser material processing by the use of adaptive optics

    NASA Astrophysics Data System (ADS)

    Neubauer, Norbert; Hoffmann, Peter

    1994-11-01

    The use of adaptive optics in the beam delivery system of CO2 laser machines is known as a powerful method to optimize the processing results. Focus radius and position can be controlled independently of one another by the appropriate choice of the adaptive optics focal lengths. The improvement of the processing results by the compensation of varying beam path lengths is discussed for CO2 laser beam cutting. A new method for the automatic adjustment of focus parameters to the demands of the process is shown for the examples of cutting mild steels and stainless steels.

  9. Finger Length

    NSDL National Science Digital Library

    American Association for the Advancement of Science (; )

    2005-03-28

    This Science Update explores male agression patterns and their correlation to pre-natal testosterone exposure. Although life experience plays a huge role in shaping who we are, the foundations of our personality begin in the womb. One recent study looks to finger length for signs of a man's pre-natal exposure to testosterone.n women, the index and ring finger are roughly equal in length. But in most men, the ring finger is longer. That's a result of fetal exposure to testosterone. Psychologists Alison Bailey and Pete Hurd, of the University of Alberta in Canada, studied these finger ratios in male college students. And they found that men with more dramatic differences tended to be more aggressive. Additional links to resources are given for further inquiry.

  10. MRI of Focal Liver Lesions.

    PubMed

    Albiin, Nils

    2012-05-01

    Magnetic resonance imaging, MRI has more advantages than ultrasound, computed tomography, CT, positron emission tomography, PET, or any other imaging modality in diagnosing focal hepatic masses. With a combination of basic T1 and T2 weighted sequences, diffusion weighted imaging, DWI, and hepatobiliary gadolinium contrast agents, that is gadobenate dimeglumine (Gd-BOPTA) and gadoxetic acid (Gd-EOB), most liver lesions can be adequately diagnosed. Benign lesions, as cyst, hemangioma, focal nodular hyperplasia, FNH or adenoma, can be distinguished from malignant lesions. In a non-cirrhotic liver, the most common malignant lesions are metastases which may be hypovascular or hypervascular. In the cirrhotic liver hepatocellular carcinoma, HCC, is of considerable importance. Besides, intrahepatic cholangiocarcinoma and other less common malignancies has to be assessed. In this review, the techniques and typical MRI features are presented as well as the new algorithm issued by American Association for the Study of the Liver Diseases (AASLD). PMID:23049491

  11. MRI of Focal Liver Lesions

    PubMed Central

    Albiin, Nils

    2012-01-01

    Magnetic resonance imaging, MRI has more advantages than ultrasound, computed tomography, CT, positron emission tomography, PET, or any other imaging modality in diagnosing focal hepatic masses. With a combination of basic T1 and T2 weighted sequences, diffusion weighted imaging, DWI, and hepatobiliary gadolinium contrast agents, that is gadobenate dimeglumine (Gd-BOPTA) and gadoxetic acid (Gd-EOB), most liver lesions can be adequately diagnosed. Benign lesions, as cyst, hemangioma, focal nodular hyperplasia, FNH or adenoma, can be distinguished from malignant lesions. In a non-cirrhotic liver, the most common malignant lesions are metastases which may be hypovascular or hypervascular. In the cirrhotic liver hepatocellular carcinoma, HCC, is of considerable importance. Besides, intrahepatic cholangiocarcinoma and other less common malignancies has to be assessed. In this review, the techniques and typical MRI features are presented as well as the new algorithm issued by American Association for the Study of the Liver Diseases (AASLD). PMID:23049491

  12. [Familial focal and segmentary hyalinosis].

    PubMed

    Sánchez de la Nieta, M D; Arias, L F; Alcázar, R; de la Torre, M; González, L; Rivera, F; Blanco, J; Ferreras, I

    2003-01-01

    Focal segmental glomerulosclerosis represents a finding in several renal disorders, characterized by proteinuria and sometimes by arterial hypertension and progressive decline in renal function. There are primary (idiopathic and familial) and secundary forms. In the last 20 years several familial cases has been reported, with a great genetic heterogeneity (dominant and recessive forms) and with multiple associations with particular MHC class-I and class-II gene loci, being Al, DR3 o DR7 the most frequently reported. We described three members of same family with focal segmental hyalinosis that shared the HLA haplotype A31 B61 DR13. This association has not been described previously. We highlight that genetic and acquired factors (obesity, hypertension...) could have importance in the development of progressive renal failure in these patients. PMID:12778884

  13. SNAP satellite focal plane development

    Microsoft Academic Search

    Christopher Bebek; Carl W. Akerlof; Greg Aldering; R. Amanullah; Pierre Astier; Charles Baltay; E. Barrelet; Stephane Basa; John Bercovitz; Lars Bergstrom; Gary Berstein; Manfred Bester; Ralph C. Bohlin; Alain Bonissent; Charles R. Bower; Myron Campbell; William C. Carithers Jr.; Eugene D. Commins; C. Day; Susana E. Deustua; Richard S. DiGennaro; Anne Ealet; Richard S. Ellis; William Emmett; Mikael Eriksson; D. Fouchez; Andrew Fruchter; Jean-Francois Genat; Gerson Goldhaber; Ariel Goobar; Donald E. Groom; Henry D. Heetderks; Stephen E. Holland; Dragan Huterer; William E. Johnston; Richard W. Kadel; Armin Karcher; Alex G. Kim; William F. Kolbe; Robin E. Lafever; J. I. Lamoureux; Michael L. Lampton; Oliver Le Fèvre; Michael E. Levi; Daniel S. Levin; Eric V. Linder; Stewart C. Loken; Roger Malina; Alain Mazure; Timothy A. McKay; Shawn P. McKee; Ramon Miquel; Nicholas Morgan; E. Mortsell; N. Mostek; Stuart Mufson; J. A. Musser; Natalie A. Roe; Peter E. Nugent; Hakeem M. Oluseyi; Reynald Pain; Nicholas P. Palaio; David H. Pankow; Saul Perlmutter; Eric Prieto; David Rabinowitz; Alexandre Refregier; Jason Rhodes; Michael S. Schubnell; Michael Sholl; G. Smadja; R. Smith; George F. Smoot; Jeffrey A. Snyder; Anthony Spadafora; Andrew Szymkowiak; Gregory Tarle; Keith Taylor; A. Tilquin; Andrew D. Tomasch; D. Vincent; Henrik von der Lippe; Jean-Pierre Walder; Guobin Wang

    2003-01-01

    The proposed SuperNova\\/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square degree field in the visible and near-infrared wavelength regime. The requirements for the instrument suite and the present configuration of the focal plane concept are presented. A two year R&D phase, largely supported by the Department of Energy, is just

  14. Infrared focal plane array technology

    Microsoft Academic Search

    DEAN A. SCRIBNER; MELVIN R. KRUER; JOSEPH M. KILLIANY

    1991-01-01

    Requirements for infrared focal plane arrays (IRFPAs) for advanced infrared imaging systems are discussed, and an overview is given of different IRFPA architectures. Important IR detector structures, including photoconductive, photovoltaic, metal-insulator-semiconductor (MIS), and Schottky barrier, are reviewed. Infrared detector materials and related crystal-growth techniques are discussed, emphasizing applicability to IRFPA designs and performance. Three types of input circuit used to

  15. A 15 element focal plane array for 100 GHz

    Microsoft Academic Search

    N. R. Erickson; P. F. Goldsmith; G. Novak; R. M. Grosslein; P. J. Viscuso; R. B. Erickson; C. R. Predmore

    1992-01-01

    A focal plane imaging array receiver is described which covers the 86-115 GHz frequency range for radio astronomical observations. The 3×5 element array uses cryogenic Schottky diode mixers with integrated HEMT IF amplifiers. A cold quasi-optical filter selects the desired sideband, and terminates the image at 20 K. Polarization interleaving is used to minimize the array size on the sky.

  16. Optical design of a broadband scanning adaptive optics ophthalmoscope for the mouse eye

    NASA Astrophysics Data System (ADS)

    Sulai, Yusufu N.; Dubra, Alfredo

    2014-03-01

    The short focal length of the mouse eye gives rise to an optically thick retina (50 D). If in addition, multiple wavelengths are to be used simultaneously to image an arbitrary combination of retinal layers, the ? 10 D of longitudinal chromatic aberration means a total of 60 D of vergence must be covered. This dictates that marginal rays will cover a wide range of angles with respect to the optical axis at the pupil of a mouse (or murine) adaptive optics ophthalmoscope, in order to section through the entire retina with any wavelength simultaneously. In this work, we discuss the compromises associated with the design of a mouse adaptive optics ophthalmoscope using off-the-shelf spherical reflective and refractive optics.

  17. Near-infrared optical-absorption behavior in high-beta nonlinear optical chromophore-polymer guest-host materials. II. Dye spacer length effects in an amorphous polycarbonate copolymer host.

    PubMed

    Barto, Richard R; Frank, Curtis W; Bedworth, Peter V; Ermer, Susan; Taylor, Rebecca E

    2005-06-15

    In the second of a three-part series, spectral absorption behavior of nonlinear optical (NLO) dyes incorporated into amorphous polycarbonate, comprised of a homologous series of dialkyl spacer groups extending from the midsection of the dye molecule, is characterized by UV-Vis and photothermal deflection spectroscopy. The dyes are structural analogs of the NLO dye FTC [2-(3-cyano-4-{2-[5-(2-{4-[ethyl-(2-methoxyethyl)amino]phenyl}vinyl)-3,4-diethylthiophen-2-yl]vinyl}-5,5-dimethyl-5H-furan-2-ylidene)malononitrile]. Previous Monte Carlo calculations [B. H. Robinson and L. R. Dalton, J. Phys. Chem. A 104, 4785 (2000)] predict a strong dependence of the macroscopic nonlinear optical susceptibility on the chromophore waist: length aspect ratio in electric-field-poled films arising from interactions between chromophores. It is expected that these interactions will play a role in the absorption characteristics of unpoled films, as well. The spacer groups range in length from diethyl to dihexyl, and each dye is studied over a wide range of concentrations. Among the four dyes studied, a universal dependence of near-IR loss on inhomogeneous broadening of the dye main absorption peak is found. The inhomogeneous width and its concentration dependence are seen to vary with spacer length in a manner characteristic of the near-IR loss-concentration slope at transmission wavelengths of 1.06 and 1.3 mum, but not at 1.55 mum. The lower wavelength loss behavior is assigned to purely Gaussian broadening, and is described by classical mixing thermodynamic quantities based on the Marcus theory of inhomogeneous broadening [R. A. Marcus, J. Chem. Phys. 43, 1261 (1965)], modeled as a convolution of dye-dye dipole broadening and dye-polymer van der Waals broadening. The Gaussian dipole interactions follow a Loring dipole-broadening description [R. F. Loring, J. Phys. Chem. 94, 513 (1990)] dominated by the excited-state dipole moment, and have a correlated homogeneous broadening contribution. The long-wavelength loss behavior has a non-Gaussian dye-dye dipole contribution which follows Kador's broadening analysis [L. Kador, J. Chem. Phys. 95, 5574 (1991)], with a net broadening described by a convolution of this term with a Gaussian van der Waals interaction given by Obata et al. [M. Obata, S. Machida, and K. Horie, J. Polym. Sci. B 37, 2173 (1999)], with each term governed by the dye spacer length. A minimum in broadening and loss-concentration slope at a spacer length of four carbons per alkyl at all wavelengths has important consequences for practical waveguide devices, and is of higher aspect ratio than the spherical limit shown by Robinson and Dalton to minimize dipole interactions under a poling field. PMID:16008487

  18. Multispectral Focal Plane Assembly for Satellite Remote Sensing

    SciTech Connect

    Rienstra, J. [Sandia National Labs., Albuquerque, NM (United States); Ballard, M. [Santa Barbara Research Center, Goleta, CA (United States)

    1997-12-31

    Sandia National Laboratories and several subsystem contractors are developing technologies applicable to multispectral remote sensing from space. A proof of concept multispectral sensor system is under development. The objective of building this sensor is to demonstrate and evaluate multispectral imaging technologies for various applications. The three major subsystems making up the sensor are the focal plane assembly (FPA), the cryocooler, and the telescope. This paper covers the focal plane assembly, which is the basis of the sensor system. The focal plane assembly includes sensor chip assemblies, optical filters, and a vacuum enclosure with cold shielding. Linear detector arrays provide spatial resolution in the cross-track direction for a pushbroom imager configuration. The optical filters define 15 spectral bands in a range from 0.45 microns to 10.7 microns. All the detector arrays are mounted on a single focal plane and are designed to operate at 75 K. No beam splitters are used. The four spectral bands covering the visible to near infrared have roughly 2400 pixels each, and the remaining 11 spectral bands have roughly 600 pixels each. The average total rate of multispectral data from the FPA is approximately 15.4 megapixels per second. At the time this paper is being written, the multispectral focal plane assembly is in the fabrication phase. A thermal/mechanical mockup has been built and tested for the vibration environment and to determine the thermal load. Some of the sensor chip assemblies and filters have been built and tested. Several notable features of the design are covered in the paper as well as preliminary test data.

  19. Systems considerations in mosaic focal planes

    NASA Astrophysics Data System (ADS)

    White, K. P., III

    1983-08-01

    Two key reasons for pursuing the development of mosaic focal planes are reviewed and it is shown that rapid frame repetition rate is the only requirement that can be solved no other way than through mosaic focal planes. With the view that spaceborne mosaic focal plane sensors are necessarily 'smart sensors' requiring a lot of onboard processing just to function, it is pointed out that various artificial intelligence techniques may be the most appropriate to incorporate in the data processing. Finally, a novel mosaic focal plane design is proposed, termed a virtual mosaic focal plane, in response to other system constraints.

  20. Fabrication of micro-optical devices at the end of a multimode optical fiber with negative tone lift-off EBL

    NASA Astrophysics Data System (ADS)

    Sundaram, Vijay M.; Wen, Sy-Bor

    2012-12-01

    A fabrication method based on negative tone lift off EBL is developed for constructing nano-structures at end faces of multimode optical fibers. With this new approach, precise and robust nano-structures with high spatial resolutions can be fabricated with minimum damage to the optical fiber face during the fabrication process. Based on this approach, high numerical aperture micro Fresnel zone plates (MZP) with focal lengths ˜3 µm were fabricated on the face of an optical fiber. The focusing characteristics of the fabricated MZP showed good consistency with the numerical simulations at the specified wavelength (˜405 nm).

  1. Geometrical parameter analysis of the high sensitivity fiber optic angular displacement sensor

    E-print Network

    Sakamoto, João M S; Kitano, Cláudio; Tittmann, Bernhard R

    2015-01-01

    In this work, we present an analysis of the influence of the geometrical parameters on the sensitivity and linear range of the fiber optic angular displacement sensor, through computational simulations and experiments. The geometrical parameters analyzed were the lens focal length, the gap between fibers, the fibers cladding radii, the emitting fiber critical angle (or, equivalently, the emitting fiber numerical aperture), and the standoff distance (distance between the lens and the reflective surface). Besides, we analyzed the sensor sensitivity regarding any spurious linear displacement. The simulation and experimental results showed that the parameters which play the most important roles are the emitting fiber core radius, the lens focal length, and the light coupling efficiency, while the remaining parameters have little influence on sensor characteristics. This paper was published in Applied Optics and is made available as an electronic reprint with the permission of OSA. The paper can be found at the fo...

  2. Holographic Optical Elements as Scanning Lidar Telescopes

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary K.; Rallison, Richard D.; Wilkerson, Thomas D.; Guerra, David V.

    2005-01-01

    We have developed and investigated the use of holographic optical elements (HOEs) and holographic transmission gratings for scanning lidar telescopes. For example, rotating a flat HOE in its own plane with the focal spot on the rotation axis makes a very simple and compact conical scanning telescope. We developed and tested transmission and reflection HOEs for use at the first three harmonic wavelengths of Nd:YAG lasers. The diffraction efficiency, diffraction angle, focal length, focal spot size and optical losses were measured for several HOEs and holographic gratings, and found to be suitable for use as lidar receiver telescopes, and in many cases could also serve as the final collimating and beam steering optic for the laser transmitter. Two lidar systems based on this technology have been designed, built, and successfully tested in atmospheric science applications. This technology will enable future spaceborne lidar missions by significantly lowering the size, weight, power requirement and cost of a large aperture, narrow field of view scanning telescope.

  3. Focal-plane irradiance tailoring using the concept of Woofer-Tweeter deformable mirrors.

    PubMed

    Feng, Zexin; Huang, Lei; Gong, Mali

    2014-04-21

    Deformable mirror (DM) is a common-used active freeform optical element. We introduce the concept of Woofer-Tweeter DM system for controlling focal-plane irradiance profiles. We firstly determine a freeform reflective surface for transforming a given incident laser beam into the desired focal-plane irradiance distribution by numerically solving a standard Monge-Ampère equation. Then, we use a low-bandwidth Woofer DM to approximate the required freeform reflective surface and a high-bandwidth Tweeter DM to compensate the residual error. Simulation results show that, compared with single DMs, the Woofer-Tweeter DM system brings the best focal-plane irradiance performances. PMID:24787776

  4. A Shack-Hartmann wavefront sensor projected onto the sky with reduced focal anisoplanatism

    E-print Network

    T. Butterley; G. D. Love; R. W. Wilson; R. M. Myers; T. J. Morris

    2006-02-10

    A method for producing a laser guide star wavefront sensor for adaptive optics with reduced focal anisoplanatism is presented. A theoretical analysis and numerical simulations have been carried out and the results are presented. The technique, named SPLASH (Sky-Projected Laser Array Shack-Hartmann), is shown to suffer considerably less from focal anisoplanatism than a conventional laser guide star system. The method is potentially suitable for large telescope apertures (~8m), and possibly for extremely large telescopes.

  5. Fish Tank Optics.

    ERIC Educational Resources Information Center

    McCausland, Stuart; Allard, Brian

    1997-01-01

    Describes procedures for a demonstration of the focal length of spherical lenses and mirrors using an aquarium, a flashlight, and nondairy creamer. Enables nonquantitative three-dimensional observation of these phenomena. (DDR)

  6. SNAP Satellite Focal Plane Development

    SciTech Connect

    Bebek, C.; Akerlof, C.; Aldering, G.; Amanullah, R.; Astier, P.; Baltay, C.; Barrelet, E.; Basa, S.; Bercovitz, J.; Bergstrom, L.; Berstein, G.P.; Bester, M.; Bohlin, R.; Bonissent, A.; Bower, C.; Campbell, M.; Carithers, W.; Commins, E.; Day, C.; Deustua, S.; DiGennaro, R.; Ealet, A.; Ellis, R.; Emmett, W.; Eriksson, M.; Fouchez,D.; Fruchter, A.; Genat, J-F.; Goldhaber, G.; Goobar, A.; Groom, D.; Heetderks, H.; Holland, S.; Huterer, D.; Johnson, W.; Kadel, R.; Karcher,A.; Kim, A.; Kolbe, W.; Lafever, R.; Lamoureaux, J.; Lampton, M.; Lefevre, O.; Levi, M.; Levin, D.; Linder, E.; Loken, S.; Malina, R.; Mazure, A.; McKay, T.; McKee, S.; Miquel, R.; Morgan, N.; Mortsell, E.; Mostek, N.; Mufson, S.; Musser, J.; Roe, N.; Nugent, P.; Oluseyi, H.; Pain, R.; Palaio, N.; Pankow, D.; Perlmutter, S.; Prieto, E.; Rabinowitz,D.; Refregier, A.; Rhodes, J.; Schubnell, M.; Sholl, M.; Smadja, G.; Smith, R.; Smoot, G.; Snyder, J.; Spadafora, A.; Szymkowiak, A.; Tarle,G.; Taylor, K.; Tilquin, A.; Tomasch, A.; Vincent, D.; von der Lippe, H.; Walder, J-P.; Wang, G.

    2003-07-07

    The proposed SuperNova/Acceleration Probe (SNAP) mission will have a two-meter class telescope delivering diffraction-limited images to an instrumented 0.7 square degree field in the visible and near-infrared wavelength regime. The requirements for the instrument suite and the present configuration of the focal plane concept are presented. A two year R&D phase, largely supported by the Department of Energy, is just beginning. We describe the development activities that are taking place to advance our preparedness for mission proposal in the areas of detectors and electronics.

  7. Full-field optical coherence tomography system implemented with fiber-optic components

    NASA Astrophysics Data System (ADS)

    Lee, Seung Suk; Kim, Joo Ha; Choi, Eun Seo

    2014-02-01

    We have presented full-field optical coherence tomography(FF-OCT) system implemented with fiber optics. Usually FFOCT system illuminates large area at once while conventional OCT system irradiates light at single focal point. From these reason, light guidance with single fiber waveguide is not proper in FF-OCT system and fiber-optic components is not dealt in the system implementation. In this paper, we demonstrate FF-OCT system implemented with fiber-optics, where fiber coupler and fiber-optic circulator were used to perform the function of beam splitting and optical delay line. Each arm of fiber coupler acts as reference arm and sample arm. Fiber-optic collimator and metal-coated mirror mounted on translator in the reference arm could adjust optical path length properly. Separated beam after the fiber coupler was combined after bulk beam combiner, where beam size at fiber end is expanded by large fiber-optic collimator and then illuminated to sample. The larger size beam reflected from sample was interfered with reference beam, which experienced optical delay in the reference arm. The utilization of fiber-optic components could provide merits such as easiness in optical alignment and reduction of sensitiveness to external vibration and perturbation.

  8. Rapid, Accurate, and Non-Invasive Measurement of Zebrafish Axial Length and Other Eye Dimensions Using SD-OCT Allows Longitudinal Analysis of Myopia and Emmetropization

    PubMed Central

    Collery, Ross F.; Veth, Kerry N.; Dubis, Adam M.; Carroll, Joseph; Link, Brian A.

    2014-01-01

    Refractive errors in vision can be caused by aberrant axial length of the eye, irregular corneal shape, or lens abnormalities. Causes of eye length overgrowth include multiple genetic loci, and visual parameters. We evaluate zebrafish as a potential animal model for studies of the genetic, cellular, and signaling basis of emmetropization and myopia. Axial length and other eye dimensions of zebrafish were measured using spectral domain-optical coherence tomography (SD-OCT). We used ocular lens and body metrics to normalize and compare eye size and relative refractive error (difference between observed retinal radial length and controls) in wild-type and lrp2 zebrafish. Zebrafish were dark-reared to assess effects of visual deprivation on eye size. Two relative measurements, ocular axial length to body length and axial length to lens diameter, were found to accurately normalize comparisons of eye sizes between different sized fish (R2?=?0.9548, R2?=?0.9921). Ray-traced focal lengths of wild-type zebrafish lenses were equal to their retinal radii, while lrp2 eyes had longer retinal radii than focal lengths. Both genetic mutation (lrp2) and environmental manipulation (dark-rearing) caused elongated eye axes. lrp2 mutants had relative refractive errors of ?0.327 compared to wild-types, and dark-reared wild-type fish had relative refractive errors of ?0.132 compared to light-reared siblings. Therefore, zebrafish eye anatomy (axial length, lens radius, retinal radius) can be rapidly and accurately measured by SD-OCT, facilitating longitudinal studies of regulated eye growth and emmetropization. Specifically, genes homologous to human myopia candidates may be modified, inactivated or overexpressed in zebrafish, and myopia-sensitizing conditions used to probe gene-environment interactions. Our studies provide foundation for such investigations into genetic contributions that control eye size and impact refractive errors. PMID:25334040

  9. Focal axis resolver for offset reflector antennas

    NASA Technical Reports Server (NTRS)

    Schmidt, R. F. (inventor)

    1983-01-01

    Method and apparatus for determining the focal axis of an asymmetrical antenna such as an offset paraboloid reflector whose physical rim is not coincident with the boundary of the electrical aperture but whose focal point is known is provided. A transmitting feed horn array consisting of at least two feed horn elements is positioned asymmetrically on either side of an estimated focal axis which is generally inclined with respect to the boresight axis of the antenna. The feed horn array is aligned with the estimated focal axis so that the phase centers (CP sub 1, CP sub 2) of the two feed horn elements are located on a common line running through the focal point (F) orthogonally with respect to the estimated focal axis.

  10. Imaging and quality assessment of high-harmonic focal spots.

    PubMed

    Valentin, C; Douillet, D; Kazamias, S; Lefrou, Th; Grillon, G; Augé, F; Mullot, G; Balcou, Ph; Mercère, P; Zeitoun, Ph

    2003-06-15

    We present a direct method of studying the focusability of an intense, short-pulse extreme-ultraviolet (XUV) beam obtained by high-harmonic generation. We perform near-field imaging of the focal spot of five high-harmonic orders strongly focused by a broadband toroidal mirror. To visualize the focal spot directly, we image the fluorescence induced by an XUV beam on a cerium-doped YAG crystal on a visible CCD camera. We can thus measure the harmonic spot size on a single image, together with the Strehl ratio, to evaluate the quality of focusing. Such techniques should become instrumental in optimizing the focusing conditions and reaching intensities required for exploring attosecond nonlinear optics in the XUV range. PMID:12836775

  11. Optical passive athermalization for infrared zoom system

    NASA Astrophysics Data System (ADS)

    Li, Shenghui; Yang, Changcheng; Zheng, Jia; Lan, Ning; Xiong, Tao; Li, Yong

    2007-12-01

    In an infrared zoom system, it is difficult to obtain the best thermal compensation for all effective focal length (EFL) simultaneously by moving a single lens group. According to the principle of optical passive athermalization, the equations of focal length, achromatization and athermalization of both long and short EFL are established respectively. By analyzing the thermal aberration value relations between long EFL and short EFL, the thermal aberration values of the switching groups for short EFL athermalization are calculated. Firstly, the athermalization of long EFL is designed. Then through reasonable optical materials matching of the switching groups, the short EFL achieves athermalization as well. In this paper, a re-imaging switching zoom system is designed. It has a relative aperture of f/4.0, 100% cold shield efficiency, the EFL of 180mm/30mm at 3.7-4.8?m. The long EFL includes four refractive elements and one hybrid refractive/diffractive element. The switching groups of short EFL have two types, one is composed of four refractive elements, and the other is composed of two refractive elements and one hybrid refractive/diffractive element. Both of the short EFL achieve athermalization. With the aluminum materials of system structures, the zoom system achieves optical passive athermalization. It has the diffraction limited image quality and stable image plane from -30°C to 70°C.

  12. Propagating a partially coherent radially polarized beam through aligned and misaligned ABCD optical systems

    NASA Astrophysics Data System (ADS)

    Ma, Yuzhao

    2012-05-01

    In the present work the propagation of a partially coherent radially polarized beam through aligned and misaligned ABCD optical systems is discussed. The elements of the beam coherence-polarization matrix for a partially coherent radially polarized beam propagating through these systems are derived for the first time. Using the derived analytical results the intensity distribution of the focused partially coherent radially polarized beam after a low-NA lens is investigated. It is shown that the coherence of the light source affects the beam intensity profile at the focal plane significantly, while for the given coherence of the light source the focal length of the used lens does not affect the beam intensity profile at the focal plane. This is consistent with the case of a partially coherent Hermite-Gaussian beam, as expected.

  13. Simultaneous multispectral framing infrared camera using an embedded diffractive optical lenslet array

    NASA Astrophysics Data System (ADS)

    Hinnrichs, Michele

    2011-06-01

    Recent advances in micro-optical element fabrication using gray scale technology have opened up the opportunity to create simultaneous multi-spectral imaging with fine structure diffractive lenses. This paper will discuss an approach that uses diffractive optical lenses configured in an array (lenslet array) and placed in close proximity to the focal plane array which enables a small compact simultaneous multispectral imaging camera [1]. The lenslet array is designed so that all lenslets have a common focal length with each lenslet tuned for a different wavelength. The number of simultaneous spectral images is determined by the number of individually configured lenslets in the array. The number of spectral images can be increased by a factor of 2 when using it with a dual-band focal plane array (MWIR/LWIR) by exploiting multiple diffraction orders. In addition, modulation of the focal length of the lenslet array with piezoelectric actuation will enable spectral bin fill-in allowing additional spectral coverage while giving up simultaneity. Different lenslet array spectral imaging concept designs are presented in this paper along with a unique concept for prefiltering the radiation focused on the detector. This approach to spectral imaging has applications in the detection of chemical agents in both aerosolized form and as a liquid on a surface. It also can be applied to the detection of weaponized biological agent and IED detection in various forms from manufacturing to deployment and post detection during forensic analysis.

  14. Focal epithelial hyperplasia - an update.

    PubMed

    Said, Ahmed K; Leao, Jair C; Fedele, Stefano; Porter, Stephen R

    2013-07-01

    Focal epithelial hyperplasia (FEH) is an asymptomatic benign mucosal disease, which is mostly observed in specific groups in certain geographical regions. FEH is usually a disease of childhood and adolescence and is generally associated with people who live in poverty and of low socioeconomic status. Clinically, FEH is typically characterized by multiple, painless, soft, sessile papules, plaques or nodules, which may coalesce to give rise to larger lesions. Human papillomavirus (HPV), especially genotypes 13 and 32, have been associated and detected in the majority of FEH lesions. The clinical examination and social history often allow diagnosis, but histopathological examination of lesional tissue is usually required to confirm the exact diagnosis. FEH sometimes resolves spontaneously however, treatment is often indicated as a consequence of aesthetic effects or any interference with occlusion. There remains no specific therapy for FEH, although surgical removal, laser excision or possibly topical antiviral agents may be of benefit. There remains no evidence that FEH is potentially malignant. PMID:23061874

  15. Optimal focal-plane restoration

    NASA Technical Reports Server (NTRS)

    Reichenbach, Stephen E.; Park, Stephen K.

    1989-01-01

    Image restoration can be implemented efficiently by calculating the convolution of the digital image and a small kernel during image acquisition. Processing the image in the focal-plane in this way requires less computation than traditional Fourier-transform-based techniques such as the Wiener filter and constrained least-squares filter. Here, the values of the convolution kernel that yield the restoration with minimum expected mean-square error are determined using a frequency analysis of the end-to-end imaging system. This development accounts for constraints on the size and shape of the spatial kernel and all the components of the imaging system. Simulation results indicate the technique is effective and efficient.

  16. Neurocysticercosis presenting as focal hydrocephalus.

    PubMed

    Malik, Azharuddin Mohammed; Shamim, Md Dilawez; Ahmad, Mehtab; Abdali, Nasar

    2014-01-01

    A 40-year-old man presented with a 2-month history of headache, nausea and vomiting, with generalised seizures for the past 15?days. On examination he had bilateral papilloedema, visual acuity was 6/6 in both eyes but perimetry showed right homonymous inferior quadrantanopia. His MRI showed numerous small cystic lesions with eccentric nodules, diffusely distributed in bilateral cerebral and cerebellar hemispheres. There was also focal hydrocephalus involving occipital and temporal horns of the left lateral ventricle leading to its selective dilation. Stool examination showed ova of Taenia solium. He was treated with albendazole, prednisone and sustained release sodium valproate for 1?month. His headache resolved and he is free of seizures. Repeat perimetry at 1?month also showed resolution of visual field defect. PMID:24962486

  17. Mechanisms of Disease: focal segmental glomerulosclerosis

    Microsoft Academic Search

    Alain Meyrier

    2005-01-01

    Focal segmental glomerulosclerosis (FSGS), a subtype of 'idiopathic nephrotic syndrome', is not a single disease, but a lesion that initially affects the glomerulus followed by the tubulointerstitium and renal vessels. The term 'FSGS' does not accurately encompass the various pathologic features of the glomerulus, which are not always focal, segmental or sclerotic. Particular variants of FSGS, such as collapsing glomerulopathy

  18. Focal plane resolution and overlapped array TDI imaging

    NASA Astrophysics Data System (ADS)

    Grycewicz, Thomas J.; Cota, Stephen A.; Lomheim, Terrence S.; Kalman, Linda S.

    2008-08-01

    In this paper we model sub-pixel image registration for a generic earth-observing satellite system with a focal plane using two offset Time Delay and Integrate (TDI) arrays in the focal plane to improve the achievable ground resolution over the resolution achievable with a single array. The modeling process starts with a high-resolution image as ground truth. The Parameterized Image Chain Analysis & Simulation SOftware (PICASSO) modeling tool is used to degrade the images to match the optical transfer function, sampling, and noise characteristics of the target system. The model outputs a pair of images with a separation close to the nominal half-pixel separation between the overlapped arrays. A registration estimation algorithm is used to measure the offset for image reconstruction. The two images are aligned and summed on a grid with twice the capture resolution. We compare the resolution in images between the inputs before overlap, the reconstructed image, and a simulation for the image which would have been captured on a focal plane with twice the resolution. We find the performance to always be better than the lower resolution baseline, and to approach the performance of the high-resolution array in the ideal case. We show that the overlapped array imager significantly outperforms both the conventional high- and low-resolution imagers in conditions with high image smear.

  19. Focal Choroidal Excavation in Best Vitelliform Macular Dystrophy: Case Report

    PubMed Central

    Esfahani, Mohammad Riazi; Esfahani, Hamid Riazi; Mahmoudi, Alireza; Johari, Mohammad Karim

    2015-01-01

    Focal choroidal excavation (FCE) was first reported as a choroidal posteriorly excavated zone without any scleral change. Choroidal excavation also divided into conforming and nonconforming type. Numerous reports demonstrated association between FCE and other disease such as choroidal neovascularization and central serous choroidoretinopathy. Here, we report a rare case of FCE in a patient with Best disease. The patient was diagnosed by spectoral domain optical coherence tomography (SD-OCT). To the best of our knowledge, our patient is the second report of choroidal excavation in Best vitelliform macular dystrophy.

  20. Beam focalization in reflection from flat dielectric subwavelength gratings.

    PubMed

    Cheng, Y C; Zeng, H; Trull, J; Cojocaru, C; Malinauskas, M; Jukna, T; Wiersma, D S; Staliunas, K

    2014-10-15

    We experimentally demonstrate the recently predicted effect of near-field focusing for light beams from flat dielectric subwavelength gratings (SWGs). This SWGs were designed for visible light 532 nm and fabricated by direct laser writing in a negative photoresist, with the refractive index n=1.5 and the period d=314??nm. The laterally invariant gratings can focus light beams without any optical axis to achieve the transversal invariance. We show that focal distances can be obtained up to 13 ?m at normal reflection for TE polarization. PMID:25361162

  1. Focal brain inflammation and autism

    PubMed Central

    2013-01-01

    Increasing evidence indicates that brain inflammation is involved in the pathogenesis of neuropsychiatric diseases. Autism spectrum disorders (ASD) are characterized by social and learning disabilities that affect as many as 1/80 children in the USA. There is still no definitive pathogenesis or reliable biomarkers for ASD, thus significantly curtailing the development of effective therapies. Many children with ASD regress at about age 3 years, often after a specific event such as reaction to vaccination, infection, stress or trauma implying some epigenetic triggers, and may constitute a distinct phenotype. ASD children respond disproportionally to stress and are also affected by food and skin allergies. Corticotropin-releasing hormone (CRH) is secreted under stress and together with neurotensin (NT) stimulates mast cells and microglia resulting in focal brain inflammation and neurotoxicity. NT is significantly increased in serum of ASD children along with mitochondrial DNA (mtDNA). NT stimulates mast cell secretion of mtDNA that is misconstrued as an innate pathogen triggering an auto-inflammatory response. The phosphatase and tensin homolog (PTEN) gene mutation, associated with the higher risk of ASD, which leads to hyper-active mammalian target of rapamycin (mTOR) signalling that is crucial for cellular homeostasis. CRH, NT and environmental triggers could hyperstimulate the already activated mTOR, as well as stimulate mast cell and microglia activation and proliferation. The natural flavonoid luteolin inhibits mTOR, mast cells and microglia and could have a significant benefit in ASD. PMID:23570274

  2. Do focal colors look particularly "colorful"?

    PubMed

    Witzel, Christoph; Franklin, Anna

    2014-04-01

    If the most typical red, yellow, green, and blue were particularly colorful (i.e., saturated), they would "jump out to the eye." This would explain why even fundamentally different languages have distinct color terms for these focal colors, and why unique hues play a prominent role in subjective color appearance. In this study, the subjective saturation of 10 colors around each of these focal colors was measured through a pairwise matching task. Results show that subjective saturation changes systematically across hues in a way that is strongly correlated to the visual gamut, and exponentially related to sensitivity but not to focal colors. PMID:24695195

  3. Mosaic focal plane for star sensors

    NASA Astrophysics Data System (ADS)

    Chang, N. C.

    1981-02-01

    The basic principles of star sensors are reviewed with reference to the advantages of replacing photodiodes, image dissectors, and vidicons with mosaic charge transfer device (CTD) focal planes. The desirable characteristics of CTD focal planes include: high uniformity, high transfer effect, low dark current, low hot and cold spots, low dead space, low angular misalignment, high coplanarity, and high thermal stability. An implementation of a mosaic CTD array star sensor which achieves high angular position accuracy and frequency attitude update is presented. Two focal plane packaging concepts, the planar and vertical board packagings, are examined.

  4. Optical zoom camera module using two poly-dimethylsiloxane deformable mirrors.

    PubMed

    Huang, Yu-Hung; Wei, Hsiang-Chun; Hsu, Wei-Yao; Cheng, Yuan-Chieh; Su, Guo-Dung John

    2014-10-10

    Miniaturization is an essential trend in the design of portable devices. Motor-driven lens technology is a traditional way to achieve autofocus and optical zoom functions. This approach usually requires considerable space and consumes significant power. Reflective optics is a methodology that not only can fold the optical path, but it has the advantage of low chromatic aberration. In this paper, we use a deformable mirror as a reflecting element in an optical zoom system. For its low Young's modulus and residual stress, we choose polydimethylsiloxane as a deformable membrane that can provide a large stroke. The optical zoom module consists of a pair of micromachined deformable mirrors. The thickness of this module is 10 mm, which enables 2× optical zoom. The smallest effective focal length is 4.7 mm at a full field angle of 52°, and the f-number is 4.4. The largest effective focal length of the module is 9.4 mm, and the f-number is 6.4. PMID:25322427

  5. Spiral conical approximations to double reflection Wolter optics

    NASA Astrophysics Data System (ADS)

    Barbera, Marco; Mineo, Teresa; Perinati, Emanuele; Schnopper, Herbert W.; Spiga, Daniele; Taibi, Angelo

    2008-07-01

    The design of a grazing incidence focusing optic obtained from a spiral approximation to multiple nested cones produces an annular image of a point source. The angular size of the annulus depends mainly on the pitch of the winding and the focal length. For a spiral conical approximation to Wolter optics, the effect is magnified by the double reflection. However, if the two conical spirals are wound one clock-wise and the other counter-clock-wise, then the aberration is partially compensated. We use a ray tracing code to evaluate advantages and disadvantages of this optical design for potential applications of a light weight optics technology based on plastic foils that we are currently investigating.

  6. Scale Length of Disk Galaxies

    NASA Astrophysics Data System (ADS)

    Fathi, K.; Allen, M.; Gonzalez-Solares, E.; Hatziminaoglou, E.; Peletier, R.

    2009-07-01

    As a part of a Euro-VO research initiative, we have undertaken a programme aimed at studying the scale length of 54909 Sa-Sd spiral galaxies from the SDSS DR6 catalogue. We have retrieved u, g, r, i, z-band images for all galaxies in order to derive the light profiles. We also calculate asymmetry parameters to select non-disturbed disks for which we will derive exponential disk scale lengths. As images in different bands probe different optical depths and stellar populations, it is likely that a derived scale length value should depend on waveband, and our goal is to use the scale length variations with band pass, inclination, galaxy type, redshift, and surface brightness, in order to better understand the nature of spiral galaxies.

  7. Far-Infrared Focal Plane Arrays

    NASA Astrophysics Data System (ADS)

    Betz, A. L.; Boreiko, R. T.; Sivananthan, S.; Zhou, Y. D.

    The development of focal plane arrays has dramatically increased the sensitivity and efficiency of optical and infrared telescopes. The versatility of HgCdTe alloy technology has been demonstrated by detector arrays with cutoff wavelengths tailored between ?c = 1-10 ?m. Although the cutoff wavelength can theoretically be extended to infinity (zero gap) by increasing the HgTe mole fraction, the required accuracy of the alloy composition is difficult to achieve with conventional liquid-phase-epitaxy (LPE). The more recent technique of molecular-beam-epitaxy (MBE), on the other hand, provides the necessary precision, and detector arrays appear feasible out to ?c = 100 ?m. Although the alloy approach should work, an alternate device structure may prove superior. Rather than alloying HgTe and CdTe, one can deposit alternating layers of the two materials in a composite structure called a superlattice (SL). Because layer thickness (rather than alloy composition) determines the cutoff wavelength in a SL, this approach should prove easier for fabricating an Eg = 0.01 eV semiconductor. Photodiodes made from SL material should also have lower tunneling currents, which are the dominant source of noise in low gap devices. This talk will describe a NASA-funded project to develop HgCdTe detectors for FIR wavelengths. Work is now in progress on the fabrication of discrete detectors, with emphasis on the superlattice approach. Within 3 years we hope to have a 32 x 32 element array for ? = 50-60 ?m. The ultimate goal is a 128 x 128 element array for ? = 50-100 ?m that could be used on a SOFIA instrument.

  8. Comparative analysis of post-focal filamentation of focused UV and IR laser pulses in air

    NASA Astrophysics Data System (ADS)

    Geints, Yu E.; Zemlyanov, A. A.; Ionin, A. A.; Mokrousova, D. V.; Seleznev, L. V.; Sinitsyn, D. V.; Sunchugasheva, E. S.

    2015-04-01

    We report the results of laboratory experiments and numerical calculations of the spatial position and structure of a plasma channel produced in air by high-power focused femtosecond laser radiation with wavelengths of 740 and 248 nm as a result of its self-focusing and filamentation. A comparative analysis of the physical patterns of filamentation of IR and UV laser beams with variations in the beam focal length, transverse size and power is performed. It is found that a plasma channel beyond the linear focal waist of the laser beam is formed differently for two different spectral ranges.

  9. Focal renal masses: magnetic resonance imaging

    SciTech Connect

    Choyke, P.L.; Kressel, H.Y.; Pollack, H.M.; Arger, P.M.; Axel, L.; Mamourian, A.C.

    1984-08-01

    Thirty patients with focal renal masses were evaluated on a .12-Tesla resistive magnetic resonance unit using partial saturation and spin echo pulse sequence. Fifteen patients had cystic lesions, nine patients had renal cell carcinoma, two had metastatic lesions, one had an angiomyolipoma, and three had focal bacterial infection. Renal cell carcinomas demonstrated areas of increased signal using a partial saturation sequence. Magnetic resonance imaging accurately detected perinephric extension and vascular invasion in all patients. Metastatic disease to the kidney was uniformly low in signal, in contrast to primary renal cell carcinoma; an angiomyolipoma demonstrated very high signal intensity. Two masses resulting from acute focal bacterial nephritis were uniformly low in signal. Magnetic resonance imaging appears to be an accurate way of detecting, identifying, and staging focal renal masses.

  10. Vasoconstrictive neurovascular coupling during focal ischemic depolarizations

    E-print Network

    Boas, David

    Vasoconstrictive neurovascular coupling during focal ischemic depolarizations Hwa Kyoung Shin1 and Neurovascular Regulation Laboratory, Massachusetts General Hospital, Harvard Medical School, Charlestown lesion development in ischemic mouse brain. Mitigating the vasoconstrictive neurovascular coupling during

  11. Digital-pixel focal plane array development

    E-print Network

    Brown, Matthew G.

    Since 2006, MIT Lincoln Laboratory has been developing Digital-pixel Focal Plane Array (DFPA) readout integrated circuits (ROICs). To date, four 256 × 256 30 µm pitch DFPA designs with in-pixel analog to digital conversion ...

  12. Optimization of the optical interconnection between microlens and channel waveguide arrays

    NASA Astrophysics Data System (ADS)

    Linares, Jesus; de La Fuente, Raul

    1990-07-01

    Optical interconnection between a linear microlens and a channel waveguide array was optimized for use in integrated optical computing. It was shown that, by optimizing the coupling efficiency limited by diffraction between microlenses and channel waveguides, an efficient IO device module can be designed. Attention was given to a coupled microlens-channel waveguide array in which each lens has a 200-micron focal length, and each channel waveguide has a 4-micron modal field diameter; the working wavelength was 1.57 micron.

  13. Finding the Focal Axes of Offset Antennas

    NASA Technical Reports Server (NTRS)

    Schmidt, R. F.

    1982-01-01

    Focal axis of offset paraboloidal reflector antennas determined by direct measurement instead of trial and error. Two feed horns transmit sum or difference pattern to antenna under test, which reflects energy to far-field detector. When axis of feed horns coincides with focal axis of antenna reflector, far-field detector records minimum in amplitude difference and maximum in absolute-magnitude phase difference between sum and difference signals.

  14. Surgery for drug-resistant focal epilepsy.

    PubMed

    Rao, Malla Bhaskara; Arivazhagan, Arimappamagan; Sinha, Sanjib; Bharath, Rose Dawn; Mahadevan, Anita; Bhat, Maya; Satishchandra, Parthasarthy

    2014-03-01

    During the colloquium on drug-resistant epilepsy (DRE) at National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore on August 16-18, 2013, a number of presentations were made on the surgically remediable lesional epilepsy syndromes, presurgical evaluation, surgical techniques, neuropathology of drug resistance focal epilepsy and surgical outcome. This pictorial essay with the illustrative case examples provides an overview of the various surgical techniques for the management of drug-resistant focal epilepsy. PMID:24791080

  15. Surgery for drug-resistant focal epilepsy

    PubMed Central

    Rao, Malla Bhaskara; Arivazhagan, Arimappamagan; Sinha, Sanjib; Bharath, Rose Dawn; Mahadevan, Anita; Bhat, Maya; Satishchandra, Parthasarthy

    2014-01-01

    During the colloquium on drug-resistant epilepsy (DRE) at National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore on August 16-18, 2013, a number of presentations were made on the surgically remediable lesional epilepsy syndromes, presurgical evaluation, surgical techniques, neuropathology of drug resistance focal epilepsy and surgical outcome. This pictorial essay with the illustrative case examples provides an overview of the various surgical techniques for the management of drug-resistant focal epilepsy. PMID:24791080

  16. Impaired Visual Function in Focal Idiopathic Dystonia

    Microsoft Academic Search

    Th. Büttner; W. Kuhn; M. Dietz; Th. Müller; Th. Postert; H. Przuntek; F. L. Welter

    1999-01-01

    Visual dysfunctions have previously been reported in Parkinson’s disease and Huntington’s chorea. To further characterize the pathophysiology of vision in basal ganglion diseases, we studied visual functions in focal dystonic syndromes. Colour discrimination and visual contrast perception were investigated in 37 patients with focal idiopathic dystonia (ID; 20 spasmodic torticollis, 17 blepharospasm) and in age- and sex-matched healthy volunteers using

  17. Diffractive microlens array monolithic integration with PtSi focal plane array

    Microsoft Academic Search

    Yi Li; Xinjian Yi; Liping Cai; Sihai Chen; Sixian Chen

    2000-01-01

    A diffractive microlens arrays can completely collect the light at the focal plane and concentrate it into a smaller spot size on the detector plane; the photodetector area can be substantially reduced. Increased gamma radiation hardening and noise reduction result from the decrease in photodectector sensitive area. The diffractive microlens arrays have been designed by considering the independent optical and

  18. Diffractive Microlens Array Monolithic Integration with PtSi Focal Plane array

    Microsoft Academic Search

    Yi Li; Xinjian Yi; Liping Cai

    2000-01-01

    Diffractive microlens arrays can completely collect the light at the focal plane and concentrate it into a smaller spot size on the detector plane, the photodetector area can be substantially reduced. Increased gamma radiation hardening and noise reduction result from the decrease in photodetector sensitive area. The diffractive microlens arrays have been designed by considering the correlative optical and processing

  19. The finite element modeling and thermal analysis of the special focal plane of LAMOST

    Microsoft Academic Search

    Heng Zuo; Dehua Yang; Guoping Li

    2010-01-01

    The Large Area Multi-Object Spectroscopic Telescope (LAMOST) is a meridian reflecting Schmidt telescope with a 40m optical axis between the reflecting Schmidt plate and the spherical primary mirror. In the middle is located the spherical focal plane, through which there are corresponding 4000+ unit mounting holes for the fibers, and on its back, there attached a support truss adapted from

  20. Laser-beam attenuation for spatial profiling of small focal spots

    SciTech Connect

    Nichols, D.B.; Hall, R.B.

    1980-08-01

    We describe an attenuation scheme for high-power laser beams which uses only two optical surfaces and is continuously variable over several orders of magnitude. We demonstrate its application to the spatial profiling of a pulsed DF laser focal spot with 10/sup -2/ cm diameter and >10/sup 10/ W/cm/sup 2/ peak irradiance.

  1. Interferometric control of fiber lengths for a coherent telescope array

    Microsoft Academic Search

    F. Reynaud; J. J. Alleman; P. Connes

    1992-01-01

    A laser-controlled servosystem that keeps the fiber-optical length difference stable is described. A new interferometer design is proposed which makes it possible to introduce an arbitrary number of telescopes with simultaneous control of all fiber lengths from an unstabilized laser. The interferometer compares the optical length of all the filters (called slaves) with that of a unique master fiber.

  2. Integrated fiber optic probe for dynamic light scattering

    NASA Technical Reports Server (NTRS)

    Dhadwal, Harbans S.; Khan, Romel R.; Suh, Kwang

    1993-01-01

    An integrated fiber optic probe, comprising a monomode optical fiber fusion spliced to a short length of a graded-index multimode fiber, is fabricated for use as a coherent receiver in dynamic light scattering. The multimode fiber is cleaved to provide a gradient-index fiber lens with a focal length of 125 microns and an f-number close to unity. An integrated fiber receiver is used to measure the intensity-intensity autocorrelation data from a 0.05 percent by weight concentration of an aqueous suspension of polystyrene latex spheres. Analysis of 100 independent data sets indicates that the particle size can be recovered with an accuracy of +/- 1 percent.

  3. Ultrasonic variable-focus optical lens using transparent gel

    NASA Astrophysics Data System (ADS)

    Koyama, D.; Isago, R.; Nakamura, K.

    2012-12-01

    Varifocal imaging using an optical lens that employs acoustic radiation force and a viscoelastic material and that has no mechanical moving parts is investigated. The lens has a simple and thin structure that consists of an annular ultrasonic transducer and silicone gel. An axially symmetric acoustic standing wave can be generated in the gel by exciting a vibration mode in the radial direction on the transducer. The lens profile can be altered by varying the acoustic radiation force of the transducer. The focal length can be controlled by varying the transducer input voltage so that the lens functions as a variable-focus lens.

  4. The Optical Layout Of The HEGRA Cherenkov Telescopes

    NASA Astrophysics Data System (ADS)

    Akhperjanian, A.; Kankanian, R.; Sahakian, V.; Heusler, A.; Wiedner, C.-A.; Wirth, H.

    The raytracing technique was used to derive a suitable design for the HEGRA system of Cherenkov telescopes, which is at present commissioned at La Palma. The reflectors with a diameter of ~ 3.9 m consist of 30 spherical mirrors with focal lengths in the range of 4.88 - 4.94 m. It is shown that 93% of the photons from the Cherenkov light emitted by an extended air shower are contained in the camera pixels, 0.25 deg in diameter, for the full field of view of theta = +/- 2.5 deg. The optical performance of the HEGRA design is compared to other layouts.

  5. Focal Mechanism determination of local M

    NASA Astrophysics Data System (ADS)

    Vales, Dina; Custório, Susana; Carrilho, Fernando

    2015-04-01

    We determine the focal mechanisms of local small (ML<3.9) earthquakes that occurred between 2013 and 2014 in mainland Portugal. These low magnitude events were recorded by several stations that provide first-motion polarity solutions. However, only few stations are located near the epicenter and record a waveform with a signal-to-noise ratio (SNR) high enough to allow full waveform modelling. To overcome this limitation, we used a new approach called cyclic scanning of the polarity solutions (CSPS) (Fojtíková and Zahradnik, 2014), which performs a joint inversion of full waveform and first motion polarities to retrieve the focal mechanism. This methodology has the advantage of yielding reliable focal mechanism solutions, even when high SNR waveforms are available from only a few near field stations (or in the limiting case, only with one single station). To apply the CSPS method one needs to: i) run the the FOCal MEChanism (FOCMEC) code (Snoke, 2003) to obtain a suite of the DC solutions corresponding to the first motion polarities, and then ii) perform the waveform modelling in order to decrease the uncertainty. The ISOLated Asperities (ISOLA) software (Sokos and Zahradník, 2008, 2013) is used in this second step. We applied this method to weak events recorded by a network of 30 broadband seismic stations that transmit data in real-time to Instituto Português do Mar e da Atmosfera (IPMA), the institution responsible for seismic monitoring in Portugal. We interpret the obtained fault plane solutions in light of active faults and regional tectonics, and in comparison with focal mechanisms previously inferred for events in the region. The focal mechanisms obtained for small earthquakes allow us to significantly expand the database of available focal mechanisms in mainland Portugal, contributing to the understanding of active deformation in the region.

  6. Hand-held optical fuel pin scanner

    DOEpatents

    Kirchner, T.L.; Powers, H.G.

    1980-12-07

    An optical scanner for indicia arranged in a focal plane perpendicular to an optical system including a rotatable dove prism. The dove prism transmits a rotating image to a stationary photodiode array.

  7. Design of 10x uncooled thermal infrared zoom optical system

    NASA Astrophysics Data System (ADS)

    Mu, Da; Du, Yu-nan; Mi, Shi-long; Guo, Yan-chi

    2013-09-01

    For 320x240 pixel2 uncooled focal plane array detector, an infrared continuous zoom optical system of 10x zoom ratio for long-wavelength is designed in this paper. This system can be applied in joint transform correlator and other infrared tracing systems. The spectral band of the system is 8?m~12?m, the focal length is 20mm ~200mm , and the F number of the system is 2. The relative aperture is invariant during the zoom process, and the variable magnification curve and compensation curve are smooth as well. The system only consists of 7 lenses and one aspherical surface. The results have shown that when the maximum spatial frequency is 17lp/mm, the MTF(Modulation Transfer Function) curves in the whole range of focal length are all above 0.5 which are closed to diffraction limited curve. The stability of image plane is well, and the imaging quality is perfect, which show that the system meets the requirement of technical specification.

  8. End effects in optical fibres

    NASA Astrophysics Data System (ADS)

    Allington-Smith, Jeremy; Dunlop, Colin; Lemke, Ulrike; Murray, Graham

    2013-12-01

    The performance of highly multiplexed spectrographs is limited by focal ratio degradation (FRD) in the optical fibres. It has already been shown that this is caused mainly by processes concentrated around the mounting points at the ends of the fibres. We use the thickness of rings produced in the far-field when a fibre is illuminated by a collimated beam, to estimate the size of the region where the FRD is generated. This requires the development of a new model, using features of existing ray-tracing and wave-based models, which fits existing data very well. The results suggest that the amount of FRD is primarily determined by the length of fibre bonded into the supporting ferrule. We point out the implications for the production of future fibre systems.

  9. FocalCall: An R Package for the Annotation of Focal Copy Number Aberrations

    PubMed Central

    Krijgsman, Oscar; Benner, Christian; Meijer, Gerrit A; van de Wiel, Mark A; Ylstra, Bauke

    2014-01-01

    In order to identify somatic focal copy number aberrations (CNAs) in cancer specimens and to distinguish them from germ-line copy number variations (CNVs), we developed the software package FocalCall. FocalCall enables user-defined size cutoffs to recognize focal aberrations and builds on established array comparative genomic hybridization segmentation and calling algorithms. To distinguish CNAs from CNVs, the algorithm uses matched patient normal signals as references or, if this is not available, a list with known CNVs in a population. Furthermore, FocalCall differentiates between homozygous and heterozygous deletions as well as between gains and amplifications and is applicable to high-resolution array and sequencing data. PMID:25506197

  10. Design of an infrared four-mirror optical system with large relative aperture

    NASA Astrophysics Data System (ADS)

    Cong, Bin; Wu, Zheng

    2015-04-01

    Reflective optics is used widely in optical systems for their achromatization, large aperture and lightweight compared with refractive systems. An infrared four-mirror optical system with large relative aperture working in the 7.7?10.3 micron long wavelength infrared band is designed by using four reflective mirrors. The design principle, design results are described in this paper. The system has a circinal wide field of view with 1.5°×1.5°. The MTF of the system is diffraction-limited and the distortion is less than 1.0%. The ratio of focal length to total length is about 1/1.04,so the structure of the system is compact. The image quality is evaluated for each field, which shows that the design makes a good system with high image quality.

  11. Measuring microfocus focal spots using digital radiography

    SciTech Connect

    Fry, David A [Los Alamos National Laboratory

    2009-01-01

    Measurement of microfocus spot size can be important for several reasons: (1) Quality assurance during manufacture of microfocus tubes; (2) Tracking performance and stability of microfocus tubes; (3) Determining magnification (especially important for digital radiography where the native spatial resolution of the digital system is not adequate for the application); (4) Knowledge of unsharpness from the focal spot alone. The European Standard EN 12543-5 is based on a simple geometrical method of calculating focal spot size from unsharpness of high magnification film radiographs. When determining microfocus focal spot dimensions using unsharpness measurements both signal-to-noise (SNR) and magnification can be important. There is a maximum accuracy that is a function of SNR and therefore an optimal magnification. Greater than optimal magnification can be used but it will not increase accuracy.

  12. Three-dimensional surface profiling and optical characterization of liquid microlens using a Shack–Hartmann wave front sensor

    PubMed Central

    Li, Chenhui; Hall, Gunnsteinn; Zeng, Xuefeng; Zhu, Difeng; Eliceiri, Kevin; Jiang, Hongrui

    2011-01-01

    We demonstrate three-dimensional (3D) surface profiling of the water–oil interface in a tunable liquid microlens using a Shack–Hartmann wave front sensor. The principles and the optical setup for achieving 3D surface measurements are presented and a hydrogel-actuated liquid lens was measured at different focal lengths. The 3D surface profiles are then used to study the optical properties of the liquid lens. Our method of 3D surface profiling could foster the improvement of liquid lens design and fabrication, including surface treatment and aberration reduction. PMID:22046057

  13. Relation between Axial Length and Ocular Parameters

    Microsoft Academic Search

    Sang Hoon Park; Ki Ho Park; Joon Mo Kim; Chul Young Choi

    2010-01-01

    Purpose: To investigate the relation between axial length (AL) and ocular parameters. Methods: Measurements of ocular biometric parameters were performed with an optical biometer, pachymeter, optical coherence tomography, and an automatic refractometer. AL, refractive error (RE), central corneal thickness, anterior chamber depth (ACD), corneal curvature (CC), white-to-white distance (WWD), and retinal nerve fiber layer (RNFL) thickness were measured. AL was

  14. Megapixel QWIP Focal Plane Array And 320x256 Pixel Co-Located Mid-Wave And Long-Wave Dual-Band QWIP Focal Plane Array

    Microsoft Academic Search

    S. D. Gunapala; S. V. Bandara; J. K. Liu; C. J. Hill; S. B. Rafol; J. M. Mumolo; J. T. Trinh; M. Z. Tidrow; P. D. LeVan

    Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024x1024 pixel quantum well infrared photodetector (QWIP) focal planes have been demonstrated with excellent imaging performance. The MWIR QWIP detector array has demonstrated a noise equivalent differential temperature (NE ? T) of 17 mK at a 95K operating temperature with f\\/2.5 optics at 300K background and the LWIR detector array has demonstrated a

  15. Snake beam: a paraxial arbitrary focal line.

    PubMed

    Rosen, J; Yariv, A

    1995-10-15

    The creation of paraxial arbitrary focal lines by a Fourier computer-generated hologram is demonstrated. The desired focal line is represented by a series of connected straight line segments, each of which is implemented by a radial harmonic function located on a different radial portion of the entire hologram. Each subhologram is multiplied by appropriate linear and quadratic phase functions and is shifted by some distance from the center. The two phase factors determine the location of each line segment, while the in-plane shift determines the tilt angle of the segment. PMID:19862244

  16. Snake beam: a paraxial arbitrary focal line

    NASA Astrophysics Data System (ADS)

    Rosen, Joseph; Yariv, Amnon

    1995-10-01

    The creation of paraxial arbitrary focal lines by a Fourier computer-generated hologram is demonstrated. The desired focal line is represented by a series of connected straight line segments, each of which is implemented by a radial harmonic function located on a different radial portion of the entire hologram. Each subhologram is multiplied by appropriate linear and quadratic phase functions and is shifted by some distance from the center. The two phase factors determine the location of each line segment, while the in-plane shift determines the tilt angle of the segment.

  17. Focal plane array for the GERB instrument

    NASA Astrophysics Data System (ADS)

    Nelms, Nick; Butcher, Gillian I.; Blake, Oliver; Cole, Richard; Whitford, Christopher; Holland, Andrew D.

    2004-02-01

    The Geostationary Earth Radiation Budget (GERB) instrument is an Earth observing scientific payload launched on-board the European Space Agency Meteosat Second Generation (MSG) satellite in September 2002. The instrument measures reflected and emitted radiation in two wavebands, 0.3 4 ?m and 4 30 ?m. The focal plane consists of a 256-element thermoelectric linear array operating at ~300 K and four application specific integrated circuits (ASIC) providing parallel amplification, filtering and digitisation. This paper describes in detail the design, operation and performance of the GERB focal plane array.

  18. Comparison of Computational and Optical Techniques for Image Processing

    NASA Astrophysics Data System (ADS)

    Unger, Blair; Bunton, Patrick

    2003-03-01

    This project will demonstrate complementary methods of image analysis using Fourier transforms. The computational components will use MathCAD® to calculate the Fourier transforms (FTs), while optical components will use a HeNe laser and a long focal length lens to process the FTs. The project will begin with use of simple shapes (a.k.a. -the aperture shape) to test the programming and optical outputs of the respective methods. In addition, starting with simple shapes allows for easy and straight forward conceptualization of the 2D FTs. From simple shapes, we will move to increasingly more complex apertures, until finally holograms of complex shapes (dendritic crystals and other objects) can be both optically and computationally processed (creating the FTs) and enhanced (for image clarity).

  19. Performance characterization of a PIAA complex focal plane mask

    NASA Astrophysics Data System (ADS)

    Newman, Kevin; Belikov, Ruslan; Guyon, Olivier; Pluzhnik, Eugene

    2015-01-01

    The Phase Induced Amplitude Apodization Complex Mask Coronagraph (PIAACMC) is an architecture for directly observing extrasolar planets, and can achieve performance near the theoretical limits for any direct-detection instrument. PIAACMC can be designed for centrally-obscured and segmented apertures, which is particularly useful for next-generation telescopes. The PIAACMC architecture includes aspheric PIAA optics, and a complex phase-shifting focal plane mask that provides a pi phase shift to a portion of the on-axis starlight. The phase-shifted starlight is forced to interfere destructively with the un-shifted starlight, causing the starlight to be eliminated, and allowing a region for high-contrast imaging near the star.The main challenge in designing the complex focal plane mask is to achieve deep contrast over a wide spectral band. Another challenge for the mask design is to avoid sharp features, which can be difficult to manufacture. We present a solution to the design challenge by dividing the mask into sections and optimizing the phase shift produced by each section. We also demonstrate a method to design the mask with a smooth profile. One remaining challenge is to measure the performance of the mask. We present a method to compute the phase profile of the mask based on measurements of the diffraction pattern. The computed phase profile is used to simulate the expected coronagraph performance.

  20. Axial super resolution topography of focal adhesion by confocal microscopy.

    PubMed

    Chiu, Chi-Li; Gratton, Enrico

    2013-10-01

    The protein organization within focal adhesions has been studied by state-of-the-art super resolution methods because of its thin structure, well below diffraction limit. However, to achieve high axial resolution, most of the current approaches rely on either sophisticated optics or diligent sample preparation, limiting their application. In this report we present a phasor-based method that can be applied to fluorescent samples to determine the precise axial position of proteins using a conventional confocal microscope. We demonstrate that with about 4,000 photon counts collected along a z-scan, axial localization precision close to 10 nm is achievable. We show that, with within 10 nm, the axial location of paxillin, FAK, and talin is similar at focal adhesion sites, while F-actin shows a sharp increase in height towards the cell center. We further demonstrated the live imaging capability of this method. With the advantage of simple data acquisition and no special instrument requirement, this approach could have wide dissemination and application potentials. PMID:23897846

  1. Axial Super Resolution Topography of Focal Adhesion by Confocal Microscopy

    PubMed Central

    Chiu, Chi-Li; Gratton, Enrico

    2013-01-01

    The protein organization within focal adhesions has been studied by state-of-the-art super resolution methods because of its thin structure, well below diffraction limit. However, to achieve high axial resolution, most of the current approaches rely on either sophisticated optics or diligent sample preparation, limiting their application. In this report we present a phasor-based method that can be applied to fluorescent samples to determine the precise axial position of proteins using a conventional confocal microscope. We demonstrate that with about 4,000 photon counts collected along a z-scan, axial localization precision close to 10 nm is achievable. We show that, with within 10 nm, the axial location of paxillin, FAK, and talin is similar at focal adhesion sites, while F-actin shows a sharp increase in height towards the cell center. We further demonstrated the live imaging capability of this method. With the advantage of simple data acquisition and no special instrument requirement, this approach could have wide dissemination and application potentials. PMID:23897846

  2. Long Focal Lens Camera Calibration Applied for Level-of-Detail Terrain Texture Fusion

    Microsoft Academic Search

    Wenhan Xie; Jie Yin; Liang Zhai

    2011-01-01

    In the case of surface reconstruction from uncalibrated close-range images, the models fused with level-of- detail texture are necessary for many applications. And camera calibration of different scale lens becomes the key problem. For long focal length digital camera calibration, there's its particularity. In this paper, aiming at long lens, a camera calibration method based on point-line fusion with vanishing

  3. LSST Camera Optics Design

    Microsoft Academic Search

    V J Riot; S Olivier; B Bauman; S Pratuch; L Seppala; D Gilmore; J Ku; M Nordby; M Foss; P Antilogus; N Morgado

    2012-01-01

    The Large Synoptic Survey Telescope (LSST) uses a novel, three-mirror, telescope design feeding a camera system that includes a set of broad-band filters and three refractive corrector lenses to produce a flat field at the focal plane with a wide field of view. Optical design of the camera lenses and filters is integrated in with the optical design of telescope

  4. Microarray Analysis of Focal Segmental Glomerulosclerosis

    Microsoft Academic Search

    Kristopher Schwab; David P. Witte; Bruce J. Aronow; Prasad Devarajan; S. Steven Potter; Larry T. Patterson

    2004-01-01

    Background: Focal segmental glomerulosclerosis (FSGS) is a leading cause of chronic renal failure in children. Recent studies have begun to define the molecular pathogenesis of this heterogeneous condition. Here we use oligonucleotide microarrays to obtain a global gene expression profile of kidney biopsy specimens from patients with FSGS in order to better understand the pathogenesis of this disease. Methods: We

  5. Quantum Dot Based Infrared Focal Plane Arrays

    Microsoft Academic Search

    Sanjay Krishna; Sarath D. Gunapala; Sumith V. Bandara; Cory Hill; David Z. Ting

    2007-01-01

    In the past decade, there has been active research on infrared detectors based on intersubband transitions in self-assembled quantum dots (QDs). In the past two years, at least four research groups have independently demonstrated focal plane arrays based on this technology. In this paper, the progress from the first raster scanned image obtained with a QD detector to the demonstration

  6. Large Format Multicolor QWIP Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Soibel, A.; Gunapala, S. D.; Bandara, S. V.; Liu, J. K.; Mumolo, J. M.; Ting, D. Z.; Hill, C. J.; Nguyen, J.

    2009-01-01

    Mid-wave infrared (MWIR) and long-wave infrared (LWIR) multicolor focal plane array (FPA) cameras are essential for many DoD and NASA applications including Earth and planetary remote sensing. In this paper we summarize our recent development of large format multicolor QWIP FPA that cover MWIR and LWIR bands.

  7. Interference mitigation using a focal plane array

    Microsoft Academic Search

    Chad K. Hansen; Karl F. Warnick; Brian D. Jeffs; J. Richard Fisher; Richard Bradley

    2005-01-01

    We consider the use of spatial filtering algorithms for radio frequency interference (RFI) mitigation in conjunction with a focal plane feed array of electrically small elements. Numerical simulations are used to study the performance of 7 and 19 element hexagonal dipole arrays with a 25 m reflector at an operating frequency of 1612 MHz. Using the maximum SNR algorithm to

  8. Universities: A Focal Point for Economic Development.

    ERIC Educational Resources Information Center

    Maidique, Modesto A.

    1988-01-01

    Higher education can act as a focal point of economic development. The most widely recognized type of economic development entails an association between a university, its research facilities, and private industry. An example of this partnership is the one between Stanford University and the industries in the "Silicon Valley." (MLW)

  9. [Subtle focal diffusion abnormality in the hippocampus].

    PubMed

    Macht, S; Hellen, F; Wenzel, D; Turowski, B

    2012-07-01

    A 53-year-old female patient presented with sudden onset confusion and disorientation. Further neurological examination was unremarkable and the patient showed a complete recovery after several hours. A magnetic resonance imaging (MRI) examination performed 2 days later revealed a tiny focal lesion in the lateral hippocampus in the diffusion weighted images consistent with transient global amnesia. PMID:22710991

  10. Dual band QWIP focal plane array

    NASA Technical Reports Server (NTRS)

    Gunapala, Sarath D. (Inventor); Choi, Kwong Kit (Inventor); Bandara, Sumith V. (Inventor)

    2005-01-01

    A quantum well infrared photodetector (QWIP) that provides two-color image sensing. Two different quantum wells are configured to absorb two different wavelengths. The QWIPs are arrayed in a focal plane array (FPA). The two-color QWIPs are selected for readout by selective electrical contact with the two different QWIPs or by the use of two different wavelength sensitive gratings.

  11. Indoor Mobile Optical Wireless Antennas for Portable Devices

    NASA Astrophysics Data System (ADS)

    Challa, Syam Sundar

    A high demand for increasing need for bandwidth and data rates has paved way for optical fiber and optical wireless communications into last mile solutions for optical communications. This dissertation focuses on providing a solution to obtain Optical Wireless (OW) for indoor mobile portable devices. A new optical antenna model is proposed for such portable devices. Optical sweeping in 3D using Acousto Optics Cell Arrays (AOCAs) is proposed. This Opto-electronic method provides better coverage area for Line Of Sight optical link establishment and reconnection. The proposed method also has superior and precise beam divergence manipulation capabilities. Its geometry, coverage area and mobility are analyzed. Indoor dimensions of Height (5m), Width (20m), and Length (20m) are considered. The optical antenna can sweep through the hemispherical shape in the direction of optical beam focal plane using AOCAs. The link budget analysis is done using commercially available component ratings and the optical power for the entire coverage area of the optical antenna is found to be higher than the receiver's minimum sensitivity. The limitations on the nodes such as size and power consumption are studied and the model is designed to run efficiently on power ratings of the portable device battery. The proposed optical antenna can be fabricated in the form of a cube of size 2x2x2 mm. The optical power usage at any given time ranges from 50 mW to 0.5W. The bit error rates from SNR calculations are found to be around 10-10 at data rates of up to 4 Gbps. The Line of Sight (LOS) connection time and reestablishment time ranges from 4 to 7 mus depending on the AOCA process time. VCSEL transceiver optical characteristics are simulated to verify the validity of the model.

  12. Calibration methods for division-of-focal-plane polarimeters.

    PubMed

    Powell, S Bear; Gruev, Viktor

    2013-09-01

    Division-of-focal plane (DoFP) imaging polarimeters are useful instruments for measuring polarization information for a variety of applications. Recent advances in nanofabrication have enabled the practical manufacture of DoFP sensors for the visible spectrum. These sensors are made by integrating nanowire polarization filters directly with an imaging array, and size variations of the nanowires due to fabrication can cause the optical properties of the filters to vary up to 20% across the imaging array. If left unchecked, these variations introduce significant errors when reconstructing the polarization image. Calibration methods offer a means to correct these errors. This work evaluates a scalar and matrix calibration derived from a mathematical model of the polarimeter behavior. The methods are evaluated quantitatively with an existing DoFP polarimeter under varying illumination intensity and angle of linear polarization. PMID:24103976

  13. A spectropolarimetric focal station for the ESO E-ELT

    NASA Astrophysics Data System (ADS)

    Strassmeier, Klaus G.; DiVarano, Igor; Ilyin, Ilya; Woche, Manfred; Laux, Uwe

    2012-09-01

    We present a conceptual design for a spectropolarimetric focal station for ESO's European Extremely Large Telescope (E-ELT). It uses the intermediate f/4.4 focus, the only symmetric focus of the telescope. A dual channel, full Stokesvector polarimeter provides on-axis light for the wavelength range 380-1600nm to up to two spectrographs simultaneously via two pairs of fibers. With such spectropolarimetric capability and a proper spectrograph for the optical and the near infrared wavelengths, the E-ELT would be able to provide the full parameter space of an incoming wavefront. Because of the on-axis entrance location of the polarimeter collimator and an entrance aperture of just 1.3 arcsec, the expected poor image quality of the intermediate telescope focus is not directly relevant.

  14. Measuring the Flatness of Focal Plane for Very Large Mosaic CCD Camera

    SciTech Connect

    Hao, Jiangang; Estrada, Juan; Cease, Herman; Diehl, H.Thomas; Flaugher, Brenna L.; Kubik, Donna; Kuk, Keivin; Kuropatkine, Nickolai; Lin, Huan; Montes, Jorge; Scarpine, Vic; /Fermilab

    2010-06-08

    Large mosaic multiCCD camera is the key instrument for modern digital sky survey. DECam is an extremely red sensitive 520 Megapixel camera designed for the incoming Dark Energy Survey (DES). It is consist of sixty two 4k x 2k and twelve 2k x 2k 250-micron thick fully-depleted CCDs, with a focal plane of 44 cm in diameter and a field of view of 2.2 square degree. It will be attached to the Blanco 4-meter telescope at CTIO. The DES will cover 5000 square-degrees of the southern galactic cap in 5 color bands (g, r, i, z, Y) in 5 years starting from 2011. To achieve the science goal of constraining the Dark Energy evolution, stringent requirements are laid down for the design of DECam. Among them, the flatness of the focal plane needs to be controlled within a 60-micron envelope in order to achieve the specified PSF variation limit. It is very challenging to measure the flatness of the focal plane to such precision when it is placed in a high vacuum dewar at 173 K. We developed two image based techniques to measure the flatness of the focal plane. By imaging a regular grid of dots on the focal plane, the CCD offset along the optical axis is converted to the variation the grid spacings at different positions on the focal plane. After extracting the patterns and comparing the change in spacings, we can measure the flatness to high precision. In method 1, the regular dots are kept in high sub micron precision and cover the whole focal plane. In method 2, no high precision for the grid is required. Instead, we use a precise XY stage moves the pattern across the whole focal plane and comparing the variations of the spacing when it is imaged by different CCDs. Simulation and real measurements show that the two methods work very well for our purpose, and are in good agreement with the direct optical measurements.

  15. Pupil imaging with a high sensitivity, LWIR focal plane array

    NASA Astrophysics Data System (ADS)

    LeVan, Paul D.; Hubbs, John E.; Pratt, Quinn T.

    2014-10-01

    We describe an integrated sensor assembly serving as both a component technology demonstration and a potential means of detecting distant point sources of infrared radiation. The objective of the demonstration was to show that usefully long integration times could be achieved with a low-background and well capacity, LWIR focal plane array optimized for use with cooled optics in space. The system controls extraneous background radiation with a small (150 ?m) cooled pinhole that nevertheless transmits all the radiation of a point source collected by the fore-optic. Broad waveband response (~3 to 12 ?m) results from optimization of the fore-optic for both MW and LWIR, as well as from a broadband anti-reflection coating on the field lens that is used at the pinhole to reimage the entrance aperture and its surrounding cold stop. Integration times in excess of 10 msec have been achieved for room temperature backgrounds with the FPA cold stage operated at 50 Kelvin, and noise performance has been bracketed with single frames of data collected over several integration times and over several minutes duration. However, anomalous signal behavior has been observed as the temperature of a remote blackbody increases. Although operation to date has been with a lower operability, engineering grade FPA, plans are to eventually upgrade to a higher quality device.

  16. Arc Length Gone Global

    ERIC Educational Resources Information Center

    Boudreaux, Gregory M.; Wells, M. Scott

    2007-01-01

    Everyone with a thorough knowledge of single variable calculus knows that integration can be used to find the length of a curve on a given interval, called its arc length. Fortunately, if one endeavors to pose and solve more interesting problems than simply computing lengths of various curves, there are techniques available that do not require an…

  17. Pleiades HR in Flight Geometrical Calibration : Location and Mapping of the Focal Plane

    NASA Astrophysics Data System (ADS)

    de Lussy, F.; Greslou, D.; Dechoz, C.; Amberg, V.; Delvit, J. M.; Lebegue, L.; Blanchet, G.; Fourest, S.

    2012-07-01

    The Pleiades system, ORFEO system optical component (Optical and Radar Federated Earth Observation) consists of a constellation of two satellites for very High Resolution panchromatic and multispectral optical observation of the Earth. Its mission is to cover all European civilian needs (mapping, tracking floods and fires) and defence in the category of metric resolution: 0.7m Nadir. The first Pleiades satellite was launched at the end of last year. One of the key objectives of the Pleiades HR (PHR) project is to achieve a location accuracy that will allow the use of images in GIS (Geographical Information System) without geometrical model improvement by refining on ground control points. The image location without refined model was specified with the precision of the most commonly used tool ie the civil GPS. So the location accuracy has been specified at less than 12m for 90% of the images on a nominal satellite configuration. Very special care has been taken all along the PHR project realization to achieve this very good location accuracy. The final touch is given during the in-orbit commissioning phase which lasts until June 2012. The geometric quality implies to tune the parameters involved in the geolocation model (geometric calibration): besides attitude and orbit restitution tuning (not considered here), it consists in estimating the biases between the instrument orientation and the AOCS reference frame, and also the sight line of each detector in the focal plane. This is called static geometrical model. The analysis of dynamic perturbations outside of the model are the second most important image quality objective of in-flight commissioning, not described in this paper. Finally "image quality assessment" consists in evaluating the image quality obtained in the final products. For geolocation model, it is quantified by the absolute geolocation and the pointing accuracies, and it is a main contributor in length alteration and planimetric and altimetric accuracies. In this paper we will present both the different practices we have adopted (their advantages, limitations and complementarities) and the means we are using for the operational assessment of the location quality of PHR images. We will focus on the innovative methods and mention the improvements in progress. To conclude, we will present the very first accuracy results assessed after PHR1A launch on L1 and Sensor products.

  18. Physical Activity Performance of Focal Middle School Students

    ERIC Educational Resources Information Center

    Erfle, Stephen E.; Gelbaugh, Corey M.

    2013-01-01

    Histograms of push-ups and curl-ups from a sample of more than 9,000 students show periodic spikes at five and 10 unit intervals. This article argues that these spikes are related to focal points, a game theoretic concept popularized by Nobel Laureate Thomas Schelling. Being focal on one test makes one more likely to be focal on the other. Focal

  19. Microtubule-Actin Cross-talk at Focal Adhesions

    NSDL National Science Digital Library

    Alexander F. Palazzo (Columbia University; Department of Anatomy and Cell Biology REV)

    2002-07-02

    Focal adhesions are dynamic structures in which traction forces are exerted against the substratum during cell migration and are sites for the organization of signaling complexes. Palazzo and Gundersen discuss how focal adhesions may also be the site of cross-talk between the actin-based and microtubule-based cytoskeletons. Microtubules appear to deliver factors that can regulate the formation and dissolution of focal adhesions, whereas focal adhesions contribute to microtubule localization and stability.

  20. Formation of optical microlens by laser polymerization method

    NASA Astrophysics Data System (ADS)

    Suzuki, Kaoru

    2001-11-01

    Optical lens of micrometer order diameter for coupling between optical fiber and laser diode were formed by argon ion laser polymerization method at visible light cured resin. Test resin materials consisted of triethylene glycol dimethacrylate for main resin, camphorquinon for photo initiator of visible light area, hydroquinon for inhibitor, and N,N-dimethylmethacrylate for reducing agent. In order to obtain the micro lens of short focal length and small spherical aberration, the use of this technique makes it possible to simultaneously form the polymerized aria on glass plate at the argon ion laser beam irradiation zone. The polmerized aria made a high quality micro lens without using molding pattern. We have verified our claims with visual inspection, ray trajectory calculations for measurement of side long spherical aberration (transverse aberration), Fourier transform infrared spectroscopy for degree of conversion analysis of polymerized resin area, and Duc de Chaulnes method for measurement of lens shape. The lens has a diameter of 300micrometers or more, a focal length of 500micrometers or more with an NA of 0.5, and transverse aberration plot of about 100% of the within the limits of +/- 25micrometers . This method can be applied for producing circular, non-circular, linear, and array micro lenses by scanning or patterning of argon ion laser beam.

  1. Extended depth of focus adaptive optics spectral domain optical coherence tomography

    PubMed Central

    Sasaki, Kazuhiro; Kurokawa, Kazuhiro; Makita, Shuichi; Yasuno, Yoshiaki

    2012-01-01

    We present an adaptive optics spectral domain optical coherence tomography (AO-SDOCT) with a long focal range by active phase modulation of the pupil. A long focal range is achieved by introducing AO-controlled third-order spherical aberration (SA). The property of SA and its effects on focal range are investigated in detail using the Huygens-Fresnel principle, beam profile measurement and OCT imaging of a phantom. The results indicate that the focal range is extended by applying SA, and the direction of extension can be controlled by the sign of applied SA. Finally, we demonstrated in vivo human retinal imaging by altering the applied SA. PMID:23082278

  2. Curved Focal-Plane Arrays Using Back-Illuminated High-Purity Photodetectors

    NASA Technical Reports Server (NTRS)

    Nikzad, Shouleh; Hoenk, Michael E.

    2003-01-01

    Curved-focal-plane arrays of back-illuminated silicon-based photodetectors are being developed. The basic idea is to improve the performance of an imaging instrument and simplify the optics needed to obtain a given level of performance by making an image sensor (e.g., a photographic film or an array of photodetectors) conform to a curved focal surface, instead of following the customary practice of designing the optics to project an image onto a flat focal surface. Eyes are natural examples of optical systems that have curved focal surfaces on which image sensors (retinas) are located. One prior approach to implementation of this concept involves the use of curved-input-surface microchannel plates as arrays of photodetectors. In comparison with microchannel plates, these curved-focal-plane arrays would weigh less, operate at much lower voltages, and consume less power. It should also be possible to fabricate the proposed devices at lower cost. It would be possible to fabricate an array of photodetectors and readout circuitry in the form of a very-large-scale integrated (VLSI) circuit on a curved focal surface, but it would be difficult and expensive to do so. In a simple and inexpensive alternate approach, a device (see figure) would have (1) a curved back surface, onto which light would be focused; and (2) a flat front surface, on which VLSI circuitry would be fabricated by techniques that are well established for flat surfaces. The device would be made from ultrapure silicon, in which it is possible to form high-resistivity, thick photodetectors that are fully depleted through their thicknesses. (As used here, "thick means having a thickness between a fraction of a millimeter and a few millimeters.) The back surface would be polished to the curvature of the focal surface of the intended application. To enable the collection of charge carriers excited by photons near the back surface or in the bulk of the device, it would be necessary to form a transparent or semitransparent back-surface electrode, possibly by delta doping. [Delta doping is so named because its density-vs.-depth characteristic is reminiscent of the Dirac function (impulse function): the dopant is concentrated in a very thin layer - nominally, a single atomic layer.

  3. Use of focal mechanisms to determine stress: A control study

    Microsoft Academic Search

    Andrew Jay Michael

    1987-01-01

    To allow focal mechanisms to be inverted for the stress field requires a different inversion algorithm than for slickenside data because focal mechanisms do not represent fault slip data unless one can decide which nodal plane is the fault plane. If one can decide which nodal plane is the fault plane, then the focal mechanisms can be inverted with the

  4. Dynamic reactive astrocytes after focal ischemia

    PubMed Central

    Ding, Shinghua

    2014-01-01

    Astrocytes are specialized and most numerous glial cell type in the central nervous system and play important roles in physiology. Astrocytes are also critically involved in many neural disorders including focal ischemic stroke, a leading cause of brain injury and human death. One of the prominent pathological features of focal ischemic stroke is reactive astrogliosis and glial scar formation associated with morphological changes and proliferation. This review paper discusses the recent advances in spatial and temporal dynamics of morphology and proliferation of reactive astrocytes after ischemic stroke based on results from experimental animal studies. As reactive astrocytes exhibit stem cell-like properties, knowledge of dynamics of reactive astrocytes and glial scar formation will provide important insights for astrocyte-based cell therapy in stroke. PMID:25657720

  5. Giant hepatic angiomyolipoma simulating focal nodular hyperplasia

    Microsoft Academic Search

    Masaki Miyahara; Michio Kobayashi; Izuru Tada; Kazunari Okada; Koichi Sato; Yang Kim; Tadayasu Hiraoka; Shigeo Yokoyama

    1988-01-01

    A case of hepatic angiomyolipoma occurring in a 41-year-old woman, the eighteenth case in literature, is reported herein.\\u000a The radiographic imagings of the tumor simulated those of focal nodular hyperplasia; namely, the tumor was hyperechoic on\\u000a ultrasound, hypodense on computed tomography, hypervascular on angiography, and exhibited an uptake of technetium (Tc)-99m\\u000a phytate. The diagnosis was established after successful removal of

  6. Likelihood analysis of earthquake focal mechanism distributions

    NASA Astrophysics Data System (ADS)

    Kagan, Yan Y.; Jackson, David D.

    2015-06-01

    In our paper published earlier we discussed forecasts of earthquake focal mechanism and ways to test the forecast efficiency. Several verification methods were proposed, but they were based on ad hoc, empirical assumptions, thus their performance is questionable. We apply a conventional likelihood method to measure the skill of earthquake focal mechanism orientation forecasts. The advantage of such an approach is that earthquake rate prediction can be adequately combined with focal mechanism forecast, if both are based on the likelihood scores, resulting in a general forecast optimization. We measure the difference between two double-couple sources as the minimum rotation angle that transforms one into the other. We measure the uncertainty of a focal mechanism forecast (the variability), and the difference between observed and forecasted orientations (the prediction error), in terms of these minimum rotation angles. To calculate the likelihood score we need to compare actual forecasts or occurrences of predicted events with the null hypothesis that the mechanism's 3-D orientation is random (or equally probable). For 3-D rotation the random rotation angle distribution is not uniform. To better understand the resulting complexities, we calculate the information (likelihood) score for two theoretical rotational distributions (Cauchy and von Mises-Fisher), which are used to approximate earthquake source orientation pattern. We then calculate the likelihood score for earthquake source forecasts and for their validation by future seismicity data. Several issues need to be explored when analyzing observational results: their dependence on forecast and data resolution, internal dependence of scores on forecasted angle and random variability of likelihood scores. Here, we propose a simple tentative solution but extensive theoretical and statistical analysis is needed.

  7. Al+LiF Coated Focal Plane

    E-print Network

    Al+LiF Coated Mirror #2 Focal Plane Assemblies (4) Detectors (2) Al+LiF Coated Mirror #1 SiC Coated Mirror #2 SiC Coated Mirror #1 Rowland Circles Al+LiF Coated Grating #2 Al+LiF Coated Grating #1 SiC of the channels are coated with silicon carbide (SiC), which provides an approximately constant reflectivity

  8. Optically coupled focal plane arrays using lenslets and multiplexers

    DOEpatents

    Veldkamp, Wilfrid B. (Lexington, MA)

    1991-01-01

    A detector array including a substrate having an array of diffractive lenses formed on the top side of the substrate and an array of sensor elements formed on the backside of the substrate. The sensor elements within the sensor array are oriented on the backside so that each sensor is aligned to receive light from a corresponding diffractive lens of the lens array. The detector array may also include a second substrate having an array of diffractive elements formed on one of its surfaces, the second substrate being disposed above and in proximity to the top side of the other substrate so that the elements on the second substrate are substantially aligned with corresponding sensor elements and diffractive lenses on the other substrate.

  9. A terahertz focal plane array using HEB superconducting mixers and MMIC IF amplifiers

    Microsoft Academic Search

    Fernando Rodriguez-Morales; K. Sigfrid Yngvesson; Eyal Gerecht; Niklas Wadefalk; John Nicholson; Dazhen Gu; Xin Zhao; Thomas Goyette; Jerry Waldman

    2005-01-01

    We present a focal plane array (FPA) designed for operation at terahertz frequencies. The FPA is based on NbN phonon-cooled hot electron bolometer mixers directly coupled to wide-band microwave monolithic integrated circuit IF amplifiers. The array incorporates all the required dc-bias and IF circuitry in a compact split-block design. We present new experimental results describing the optical coupling efficiency to

  10. 640 × 512 pixel long-wavelength infrared narrowband, multiband, and broadband QWIP focal plane arrays

    Microsoft Academic Search

    Sarath D. Gunapala; Sumith V. Bandara; John K. Liu; B. Rafol; J. M. Mutnolo

    2003-01-01

    A 640 × 512 pixel, long-wavelength cutoff, narrowband (??\\/??10%) quantum-well infrared photodetector (QWIP) focal plane array (FPA), a four-band QWIP FPA in the 4-15 ?m spectral region, and a broadband (??\\/? ? 42%) QWIP FPA having a 15.4 ?m cutoff have been demonstrated. In this paper, we discuss the electrical and optical characterization of these FPAs, and their performance. In

  11. Design, simulation and validation of a novel uncooled infrared focal plane array

    Microsoft Academic Search

    Shali Shi; Binbin Jiao; Dapeng Chen; Chaobo Li; Deyong Ding; Yi Ou; Tianchun Ye; Zhihui Duan; Xiaoping Wu; Qingchuan Zhang

    2007-01-01

    This paper describes a novel single-layer bi-material cantilever microstructure without silicon (Si) substrate for focal plane array (FPA) application in uncooled optomechanical infrared imaging system (UOIIS). The UOIIS, responding to the radiate infrared (IR) source with spectral range from 8 to 14?m, may receive an IR image through visible optical readout method. The temperature distribution of the IR source could

  12. Uncooled Infrared Imaging Using a Substrate-Free Focal-Plane Array

    Microsoft Academic Search

    Teng Cheng; Qingchuan Zhang; Xiaoping Wu; Dapeng Chen; Binbin Jiao

    2008-01-01

    A substrate-free 160 times 160 focal-plane array (FPA) with a 60-mum times 60-mum pitch has been developed and used for an optical readout uncooled infrared (IR) detector. The supporting frame of the FPA is a temperature-variable one due to its large decreases in both heat capacity and thermal conductance. This thermal characteristic significantly increases the temperature change of the microcantilever,

  13. Scenery's temperature image based on two-band uncooled focal plane array thermal images

    Microsoft Academic Search

    Yuqing He; Weiqi Jin; Xia Wang; Zhiyun Gao; Lingxue Wang; Guangrong Liu

    2002-01-01

    Dual-band uncooled Focal Plane Array (FPA) thermal imaging system adopts an Archimedes spiral cord chopper and a matched dual-band light filter to achieve two single-band IR images in one imaging system. Traditional methods of getting two bands images need two single-band thermal imagers, this system only needs one detector and one optical imaging system, so the system's structure becomes smaller

  14. [Focal therapy for prostate cancer: German version].

    PubMed

    Kasivisvanathan, V; Shah, T T; Donaldson, I; Kanthabalan, A; Moore, C M; Emberton, M; Ahmed, H U

    2015-02-01

    Focal therapy is a treatment strategy for men with localized prostate cancer that may serve as an alternative option to radical therapy. A number of minimally invasive ablative technologies are available to deliver treatment, and the energies most commonly used include high-intensity focused ultrasound and cryotherapy. The benefit of a tissue-preserving approach is the limitation of damage to key structures such as the neurovascular bundles, external urinary sphincter, rectal mucosa and bladder neck. This in turn minimizes side effects typically associated with radical therapies whilst also aiming to maintain oncological control. Over 30 single-centre studies of focal therapy have been published to date reporting excellent continence rates, good potency rates and acceptable short-term oncological outcomes. However, there are a number of controversial aspects associated with focal therapy including the index lesion hypothesis, patient selection criteria, assessment of treatment effect and the lack of medium- and long-term oncological outcomes. In the process of the adoption of new technology, there is a limited window of opportunity to provide this evidence in well-designed prospective trials. Men should be allowed to benefit from the potential advantages of this novel treatment whilst under close surveillance. An English version of this article is available under dx.doi.org/10.1007/s00120-014-3734-7. PMID:25690574

  15. Focusing of synchrotron radiation with polycapillary optics

    Microsoft Academic Search

    F. A. Hofmann; C. A. Freinberg-Trufas; S. M. Owens; S. D. Padiyar; C. A. MacDonald

    1997-01-01

    Polycapillary optics are arrays of thousands of hollow capillary tubes. Focal spots are produced from the overlap of outputs from multiple channels at distances of 10–100 mm from the output of the optic. Synchrotron focusing was performed with two polycapillary X-ray optics. The spot size for the monolithic optic was 80 ?m, which yielded a measured gain in photon flux

  16. Focusing of synchrotron radiation with polycapillary optics

    Microsoft Academic Search

    F. A. Hofmann; C. A. Freinberg-Trufas; S. M. Owens; S. D. Padiyar; C. A. MacDonald

    1997-01-01

    Polycapillary optics are arrays of thousands of hollow capillary tubes. Focal spots are produced from the overlap of outputs from multiple channels at distances of 10-100 mm from the output of the optic. Synchrotron focusing was performed with two polycapillary X-ray optics. The spot size for the monolithic optic was 80 mum, which yielded a measured gain in photon flux

  17. Great (Focal) Lengths Project 2. Due 11:59PM on Friday, March 1, 2013.

    E-print Network

    O'Brien, James F.

    to send cameras to the upper layers of the atmosphere become less expensive and more accessible. This sort that are rigidly positioned in a plastic or metallic barrel. View cameras, lenses with bellows, and tilt

  18. Single-view Perspective Shape-from-Texture with Focal Length Estimation: A Piecewise Affine Approach

    E-print Network

    Bartoli, Adrien

    the 3D shape of a surface using the Shape-From-Texture (SFT) cue. In the classical SFT setting is available at www.irit.fr/Pierre.Gurdjos/ECCV2002/ #12;ing to this intuition, it seems that uncalibrated SFT is well- posed. However, this is not true when the textons are small, which is precisely a SFT assumption

  19. A Robust Analytical Solution to Isometric Shape-from-Template with Focal Length Calibration

    E-print Network

    Bartoli, Adrien

    researched actively over the past decade. We here call this problem Shape-from- Template (SfT). Recovering the 3D deformation is equiv- alent to recovering the shape as seen in the input image. Solving SfT. An important instance of SfT is IsoSfT, where the 3D deformation is distance-preserving, in other words

  20. Dynamic focal spots registration algorithm for freeform surface measurement

    NASA Astrophysics Data System (ADS)

    Guo, Wenjiang; Zhao, Liping; Chen, I.-Ming

    2013-06-01

    In a wavefront sensing system, the raw data for surface reconstruction, either the slope matrix or curvature matrix, is obtained through centroiding on the focal spot images. Centroiding is to calculate the first moment within a certain area of interest, which encloses the focal spot. As the distribution of focal spots is correlated to the surface sampling condition, while a uniform rectangular grid is good enough to register all the focal spots of a uniformly sampled near flat surface, the focal spots of aspherical or freeform surfaces have varying shapes and sizes depending on the surface geometry. In this case, the normal registration method is not applicable. This paper proposed a dynamic focal spots registration algorithm to automatically analyze the image, identify and register every focal spot for centroiding at one go. Through experiment on a freeform surface with polynomial coefficients up to 10th order, the feasibility and effectiveness of the proposed algorithm is proved.

  1. The pressure-dependent performance of a substrate-free focal plane array in an uncooled infrared imaging system

    Microsoft Academic Search

    Zhiming Xiong; Qingchuan Zhang; Jie Gao; Xiaoping Wu; Dapeng Chen; Binbin Jiao

    2007-01-01

    Uncooled focal plane arrays (FPAs) are being developed for a wide range of infrared imaging applications. A substrate-free FPA for optical readout infrared imaging is fabricated with a pixel pitch of 120 mum. The pressure dependences of thermal conductance of a FPA with\\/without substrate are studied by modeling analysis. Infrared imaging experiments are performed to validate the modeling analysis. At

  2. Designing an all-reflective, long focus and large field of view optical system with freeform surface

    NASA Astrophysics Data System (ADS)

    Wang, Qingfeng; Cheng, Dewen; Wang, YongTian; Liu, Yue

    2012-11-01

    All-reflective optical system has been widely used in the deep space detection applications. We studied the application of freeform surface in all-reflective, off-axis optical systems, which have long effective focal length and large field of view, were designed. The freeform surface was employed to achieve better performance, while reduce the system size and weight. The starting point of the design was calculated by using the geometrical optics and properties of conic. After that we optimized the starting point using the strategy of successive approximation optimization method to reduce the design difficulty. Based on the theory of aberration, the best position of freeform surface in the off-axis system was analyzed. At last, two four-mirror optical systems with long EFL and large field of view were designed, the effective focal length are 1.95m and 4.5m, respectively; the field of view for both systems are 3°. The modulation transfer function is close to diffraction limit.

  3. Imaging Polarimetry With Polarization-Sensitive Focal Planes

    NASA Astrophysics Data System (ADS)

    Vorobiev, Dmitry; Ninkov, Z.

    2014-01-01

    We present a compact, lightweight, snapshot imaging polarimeter designed for operation in the near-infrared (NIR) and mid-infrared (MIR). Flux, polarization and spectral energy distribution are the fundamental measurements through which we infer properties of the sources of radiation such as intensity, temperature, chemical composition, emission mechanisms and structure. In recent decades, many scientific fields that utilize radiometry and spectroscopy have benefited from revolutionary improvements in instrumentation, for example, charge-coupled devices, hybridized infrared arrays, multi-object spectrometers and adaptive optics. Advances in polarimetric instrumentation have been more modest. Recently, the fabrication of microgrid polarizer arrays (MGPAs), facilitated the development of polarization-sensitive focal planes. These devices have inherent capability to measure the degree and angle of polarization across a scene (i.e., imaging polarimetry) instantaneously, without the need for multiple exposures and moving optics or multiple detectors. MGPA-based devices are compact, lightweight, and mechanically robust and perfectly suited for deployment on space-based and airborne platforms. We describe the design, operation and expected performance of MGPA-based imaging polarimeters and identify the applications for which these polarimeters are best suited.

  4. Focal damage to macaque photoreceptors produces persistent visual loss.

    PubMed

    Strazzeri, Jennifer M; Hunter, Jennifer J; Masella, Benjamin D; Yin, Lu; Fischer, William S; DiLoreto, David A; Libby, Richard T; Williams, David R; Merigan, William H

    2014-02-01

    Insertion of light-gated channels into inner retina neurons restores neural light responses, light evoked potentials, visual optomotor responses and visually-guided maze behavior in mice blinded by retinal degeneration. This method of vision restoration bypasses damaged outer retina, providing stimulation directly to retinal ganglion cells in inner retina. The approach is similar to that of electronic visual protheses, but may offer some advantages, such as avoidance of complex surgery and direct targeting of many thousands of neurons. However, the promise of this technique for restoring human vision remains uncertain because rodent animal models, in which it has been largely developed, are not ideal for evaluating visual perception. On the other hand, psychophysical vision studies in macaque can be used to evaluate different approaches to vision restoration in humans. Furthermore, it has not been possible to test vision restoration in macaques, the optimal model for human-like vision, because there has been no macaque model of outer retina degeneration. In this study, we describe development of a macaque model of photoreceptor degeneration that can in future studies be used to test restoration of perception by visual prostheses. Our results show that perceptual deficits caused by focal light damage are restricted to locations at which photoreceptors are damaged, that optical coherence tomography (OCT) can be used to track such lesions, and that adaptive optics retinal imaging, which we recently used for in vivo recording of ganglion cell function, can be used in future studies to examine these lesions. PMID:24316158

  5. Storage density and signal/noise ratio in a binary frequency-selective optical memory utilising multistage optical spectral hole burning

    SciTech Connect

    Adamson, P V [Institute of Physics, Tartu (Estonia)

    1998-09-30

    The signal/noise ratio (SNR) of a thin-film optical memory with frequency multiplexing, based on multistage optical spectral hole burning, is compared with the SNR expected for single-stage hole burning. The dependences of the SNR on the single-frequency two-dimensional data storage density are obtained for various optical diffraction images in the focal plane. It is shown that a change from single-stage to multistage hole burning provides new opportunities for increasing the basic (in the absence of frequency multiplexing) storage density, which at the 0.5 {mu}m wave-length can reach {approx} 10{sup 9} bits cm{sup -2} . When the frequency multiplexing factor is {approx} 10{sup 3} , the total storage density in two-dimensional carriers can rise to 10{sup 12} bits cm{sup -2} . (interaction of laser radiation with matter. laser plasma)

  6. Achromatic negative index lens with diffractive optics

    NASA Astrophysics Data System (ADS)

    Piao, Mingxu; Cui, Qingfeng; Zhang, Bo

    2015-02-01

    In this paper, achromatization of a negative index lens is achieved by introducing the diffractive optical elements (DOEs) into the negative index lens. The diffraction efficiency of the negative index material (NIM) DOEs is deduced based on the special propagating laws and imaging properties of negative index lenses, and the expression for microstructure height is given. As an example, an achromatic refractive–diffractive negative index lens with 150 mm focal length and 15 mm entrance pupil diameter is discussed from wavelength 0.848 ?m through wavelength 0.912 ?m to wavelength 1.114 ?m. According to the deduced expression for the NIM DOEs, the diffraction efficiency is calculated, and the diffraction efficiency curve is fitted by interpolation.

  7. Limits of spectral resolution in optical measurements

    NASA Astrophysics Data System (ADS)

    Marques, Manuel B.

    2014-08-01

    Nowadays a growing number of scientists relies on optical spectral measurements for their research. The market is full of new plug-and-play equipment for spectral analysis that take the fuss out of the measurements. As with other instruments (computers, lasers, etc.) the researcher does?t need any longer to work with someone with a post-graduate formation on the technology to be able to do excellent research. But, as in every instrument, there are limitations on the instrument use that affect its precision and resolution. Currently there is in the market a large variety of equipment for spectral measurements. They range from the huge long focal length double pass monochromators to the small pocket size USB connected array spectrometers. The different configurations have different sensitivities on the light input system, light intensity, coherence, polarization, etc. In this talk we will discuss a few of the limitations in spectral measurements that can be found in experimental setups.

  8. HST Cycle 21 Focus and Optical Monitor

    NASA Astrophysics Data System (ADS)

    Cox, Colin

    2013-10-01

    This program is the Cycle 21 implementation of the HST Optical Monitoring Program. The 9 orbits comprising this proposal will utilize ACS {Wide Field channel} and WFC3 {UVIS channel} to observe stellar cluster members in parallel with multiple exposures over an orbit. Phase retrieval performed on the PSF in each image will be used to measure primarily focus, with the ability to explore apparent coma, astigmatism, and third order spherical changes in WFC3. The goals of this program are to:1.} monitor the overall OTA focal length for the purposes of maintaining focus within science tolerances.2.} gain experience with the relative effectiveness of phase retrieval on WFC3/UVIS PSFs.3.} determine focus offset between the imagers and identify any SI-specific focus behavior and dependencies.If need is determined, future visits will be modified to interleave WFC3/IR channel and STIS/CCD focii measurements.

  9. HST Cycle 19 Focus and Optical Monitor

    NASA Astrophysics Data System (ADS)

    Cox, Colin

    2011-10-01

    This program is the Cycle 18 implementation of the HST Optical Monitoring Program. The 12 orbits comprising this proposal will utilize ACS {Wide Field channel} and WFC3 {UVIS channel} to observe stellar cluster members in parallel with multiple exposures over an orbit. Phase retrieval performed on the PSF in each image will be used to measure primarily focus, with the ability to explore apparent coma, astigmatism, and third order spherical changes in WFC3. The goals of this program are to:1.} monitor the overall OTA focal length for the purposes of maintaining focus within science tolerances.2.} gain experience with the relative effectiveness of phase retrieval on WFC3/UVIS PSFs.3.} determine focus offset between the imagers and identify any SI-specific focus behavior and dependencies.If need is determined, future visits will be modified to interleave WFC3/IR channel and STIS/CCD focii measurements.

  10. HST Cycle 20 Focus and Optical Monitor

    NASA Astrophysics Data System (ADS)

    Cox, Colin

    2012-10-01

    TBDThis program is the Cycle 20 implementation of the HST Optical Monitoring Program. The 11 orbits comprising this proposal will utilize ACS {Wide Field channel} and WFC3 {UVIS channel} to observe stellar cluster members in parallel with multiple exposures over an orbit. Phase retrieval performed on the PSF in each image will be used to measure primarily focus, with the ability to explore apparent coma, astigmatism, and third order spherical changes in WFC3. The goals of this program are to:1.} monitor the overall OTA focal length for the purposes of maintaining focus within science tolerances.2.} gain experience with the relative effectiveness of phase retrieval on WFC3/UVIS PSFs.3.} determine focus offset between the imagers and identify any SI-specific focus behavior and dependencies.If need is determined, future visits will be modified to interleave WFC3/IR channel and STIS/CCD focii measurements.

  11. HST Cycle 18 Focus and Optical Monitor

    NASA Astrophysics Data System (ADS)

    Cox, Colin

    2010-09-01

    This program is the Cycle 18 implementation of the HST Optical Monitoring Program. The 12 orbits comprising this proposal will utilize ACS {Wide Field channel} and WFC3 {UVIS channel} to observe stellar cluster members in parallel with multiple exposures over an orbit. Phase retrieval performed on the PSF in each image will be used to measure primarily focus, with the ability to explore apparent coma, astigmatism, and third order spherical changes in WFC3. The goals of this program are to:1.} monitor the overall OTA focal length for the purposes of maintaining focus within science tolerances.2.} gain experience with the relative effectiveness of phase retrieval on WFC3/UVIS PSFs.3.} determine focus offset between the imagers and identify any SI-specific focus behavior and dependencies.If need is determined, future visits will be modified to interleave WFC3/IR channel and STIS/CCD focii measurements.

  12. Simulations of partially coherent focal plane imaging arrays: Fisher matrix approach to performance evaluation

    E-print Network

    George Saklatvala; Michael P. Hobson; Stafford Withington

    2007-03-07

    Focal plane arrays of bolometers are increasingly employed in astronomy at far--infrared to millimetre wavelengths. The focal plane fields and the detectors are both partially coherent in these systems, but no account has previously been taken of the effect of partial coherence on array performance. In this paper, we use our recently developed coupled--mode theory of detection together with Fisher information matrix techniques from signal processing to characterize the behaviour of partially coherent imaging arrays. We investigate the effects of the size and coherence length of both the source and the detectors, and the packing density of the array, on the amount of information that can be extracted from observations with such arrays.

  13. Real-time imaging using a 4.3THz quantum cascade laser and a 320 \\/spl times\\/ 240 microbolometer focal-plane array

    Microsoft Academic Search

    Alan W. M. Lee; Benjamin S. Williams; Sushil Kumar; Qing Hu; John L. Reno

    2006-01-01

    We report the use of a ~50-mW peak power 4.3-THz quantum cascade laser (QCL) as an illumination source for real-time imaging with a 320 times 240 element room-temperature microbolometer focal-plane array detector. The QCL is modulated synchronously with the focal-plane array for differential imaging. Signal-to-noise ratios of ~340 are achieved at a 20-frame\\/s acquisition rate, and the optical noise equivalent

  14. Dynamic Frame Length ALOHA

    Microsoft Academic Search

    F. Schoute

    1983-01-01

    Adding frame structure to slotted ALOHA makes it very convenient to control the ALOHA channel and eliminate instability. The frame length is adjusted dynamically according to the number of garbled, successful, and empty timeslots in the past. Each terminal that has a packet to transmit selects at random one of thentimeslots of a frame. Dynamic frame length ALOHA achieves a

  15. Length of Quantum Trajectories

    Microsoft Academic Search

    Jean-Claude Zambrini; Kunio Yasue

    1984-01-01

    A notion of length for quantum mechanical trajectories is introduced within the realm of stochastic mechanics. Using a stochastic calculus of variation, one shows that the geodesic dynamics is not the free one, but the quantum evolution in the time-dependent quadratic potential associated with the Wiener process in stochastic mechanics. The length for the free evolution is also examined.

  16. Neandertal clavicle length.

    PubMed

    Trinkaus, Erik; Holliday, Trenton W; Auerbach, Benjamin M

    2014-03-25

    The Late Pleistocene archaic humans from western Eurasia (the Neandertals) have been described for a century as exhibiting absolutely and relatively long clavicles. This aspect of their body proportions has been used to distinguish them from modern humans, invoked to account for other aspects of their anatomy and genetics, used in assessments of their phylogenetic polarities, and used as evidence for Late Pleistocene population relationships. However, it has been unclear whether the usual scaling of Neandertal clavicular lengths to their associated humeral lengths reflects long clavicles, short humeri, or both. Neandertal clavicle lengths, along with those of early modern humans and latitudinally diverse recent humans, were compared with both humeral lengths and estimated body masses (based on femoral head diameters). The Neandertal do have long clavicles relative their humeri, even though they fall within the ranges of variation of early and recent humans. However, when scaled to body masses, their humeral lengths are relatively short, and their clavicular lengths are indistinguishable from those of Late Pleistocene and recent modern humans. The few sufficiently complete Early Pleistocene Homo clavicles seem to have relative lengths also well within recent human variation. Therefore, appropriately scaled clavicular length seems to have varied little through the genus Homo, and it should not be used to account for other aspects of Neandertal biology or their phylogenetic status. PMID:24616525

  17. Wave statistics in a coastal focal zone

    NASA Astrophysics Data System (ADS)

    Janssen, T. T.; Herbers, T. H. C.; Pearman, D. W.; Van Ettinger, E.; Smit, P. B.

    2014-12-01

    Wave-current dynamics in wave focal zones in exposed coastal inlets and river mouths are still poorly understood. This is in part due to lack of observations, which are complicated due to the presence of energetic waves, strong (tidal) currents, dynamic seabed morphology, and often busy ship traffic. Conventional (fixed) instruments, such as buoys and bottom-mounted current or pressure sensors, are difficult to maintain in such areas, and the spatial variability of the wave field is difficult to capture with single point measurements, or even arrays of fixed measurements. In addition to the observational difficulties, the effects of e.g. current shear, wave blocking, statistical inhomogeneity [see Smit & Janssen, 2013, J. Phys. Ocean., 43, pp 1741-1758], and nonlinearity [see Janssen & Herbers, 2009, J. Phys Ocean., 39, pp 1948-1964] on wave statistics are not fully understood, not accounted for in operational stochastic wave models, and - as a consequence - often ignored. In this paper, we consider new observational data of waves approaching the Mouth of the Columbia River undergoing bottom refraction and strong wave-current interaction. The data were collected during the 2013 ONR RIVET experiment using an array of free drifting wave-current buoys. The Lagrangian instruments capture the spatial variability of the wave field in the inlet and, by deploying them in large ensembles, resolve the (inhomogeneous and nonlinear) wave statistics in the focal zone. We discuss the use of free-drifting instruments to measure wave statistics in a coastal wave focal zone, consider the observed effects of wave inhomogeneity, and show that non-Gaussian effects are important and affect extreme wave occurrences in the Mouth of the Columbia River.

  18. Microstructured optical arrays for smart x-ray optics

    NASA Astrophysics Data System (ADS)

    Dunare, Camelia; Parkes, William; Stevenson, Tom; Michette, Alan; Pfauntsch, Slawka; Sahraei, Shahin; Shand, Matthew; Zhang, Dou; Rodriguez Sanmartin, Daniel; Button, Tim; Feldman, Charlotte; Willingale, Richard; Doel, Peter; Wang, Hongchang; James, Ady

    2009-05-01

    The Smart X-ray Optics (SXO) programme is developing advanced active-adaptive optics for X-rays. There are two main themes: large optics for applications in astronomy and small scale optics for micro-probing of biological cells and tissue samples using Ti or Cr K? radiation (4.5keV and 5.4keV, respectively) in studies related to radiation induced cancers. For the latter objective, microstructured optical arrays (MOAs) have been proposed. These consist of an array of channels deep etched in silicon. They use grazing incidence reflection to focus the X-rays through consecutive aligned arrays of channels, ideally reflecting once off a channel wall in each array. Bending the arrays allows variable focal length. The adaptivity is achieved by flexing the arrays using PZT (Lead Zirconate Titanate)-based piezo actuators. The array bending has been modelled using finite element analysis (FEA) and the results showed that for reasonable efficiency, the wall roughness of the channels should not exceed 2nm. This paper describes two techniques of fabrication the MOAs: dry etching and wet etching. The first method requires a special equipment called "inductively coupled plasma" (ICP) using Bosch processes that are designed to produce features with a high aspect ratio with vertical walls. The second method involves using an alkaline solution for etching <110> silicon wafers. This type of wafer was selected because of the large wet etch ratio between the (111) and (100) planes that leads to smooth vertical walls. For our application tetra-methyl-ammonium hydroxide (TMAH) was used as it is fully compatible with CMOS integrated circuit processes.

  19. [MR diagnosis of focal liver lesions].

    PubMed

    Palkó, András

    2004-02-15

    There are several benign and malignant processes in the liver, which are different from the normal and diffuse pathological alterations in smaller or bigger forms of hepatic nodules. Some of them are benign alterations having no clinical significance, but they have some difficulties in the differential diagnosis. The others are to be treated and their size and form must be most precisely written for the diagnosis and for the plan of the treatment important as well. The author discusses the significance of magnetic resonance examination in the differential diagnosis of focal liver lesions. PMID:15049054

  20. Focal epithelial hyperplasia in a Turkish family.

    PubMed

    Gökahmeto?lu, Selma; Ferahba?, Ayten; Canöz, Özlem

    2014-12-01

    Focal epithelial hyperplasia (FEH) is a benign proliferative condition that is more frequently found in children of certain ethnic groups. Human papillomavirus (HPV) 13 and 32 genotypes has been consistently detected in these lesions. In this study a daughter, mother and father had FEH, and HPV 13 was shown by sequence analysis in the lesions of these patients. Cryotherapy was applied to the lesions and the lesions improved, but did not recover properly. In conclusion, HPV genotyping should be performed in FEH cases. PMID:25551850

  1. Characterization of DECam focal plane detectors

    SciTech Connect

    Diehl, H.Thomas; Angstadt, Robert; Campa, Julia; Cease, Herman; Derylo, Greg; Emes, John H.; Estrada, Juan; Kibik, Donna; Flaugher, Brenna L.; Holland, Steve E.; Jonas, Michelle; /Fermilab /Madrid, CIEMAT /LBL, Berkeley /Argonne /Pennsylvania U.

    2008-06-01

    DECam is a 520 Mpix, 3 square-deg FOV imager being built for the Blanco 4m Telescope at CTIO. This facility instrument will be used for the 'Dark Energy Survey' of the southern galactic cap. DECam has chosen 250 ?m thick CCDs, developed at LBNL, with good QE in the near IR for the focal plane. In this work we present the characterization of these detectors done by the DES team, and compare it to the DECam technical requirements. The results demonstrate that the detectors satisfy the needs for instrument.

  2. Photorefractive detection of tissue optical and mechanical properties by ultrasound modulated

    E-print Network

    Wang, Lihong

    of the acoustic radiation force, which happens on a mil- lisecond time scale and can be related to the me length of 37.5 mm, focal zone length of 23 mm, and focal spot diameter of 2.2 mm. The peak acoustic, laser; BS, beam splitter; M, mirror; L1, L2, lens; PR, photorefractive crystal BSO; PMT, photomultiplier

  3. Modulation transfer function measurement of microbolometer focal plane array by Lloyd's mirror method

    NASA Astrophysics Data System (ADS)

    Druart, Guillaume; Rommeluere, Sylvain; Viale, Thibault; Guerineau, Nicolas; Ribet-Mohamed, Isabelle; Crastes, Arnaud; Durand, Alain; Taboury, Jean

    2014-05-01

    Today, both military and civilian applications require miniaturized and cheap optical systems. One way to achieve this trend consists in decreasing the pixel pitch of focal plane arrays (FPA). In order to evaluate the performance of the overall optical systems, it is necessary to measure the modulation transfer function (MTF) of these pixels. However, small pixels lead to higher cut-off frequencies and therefore, original MTF measurements that are able to extract frequencies up to these high cut-off frequencies, are needed. In this paper, we will present a way to extract 1D MTF at high frequencies by projecting fringes on the FPA. The device uses a Lloyd mirror placed near and perpendicular to the focal plane array. Consequently, an interference pattern of fringes can be projected on the detector. By varying the angle of incidence of the light beam, we can tune the period of the interference fringes and, thus, explore a wide range of spatial frequencies, and mainly around the cut-off frequency of the pixel which is one of the most interesting area. Illustration of this method will be applied to a 640×480 microbolometer focal plane array with a pixel pitch of 17µm in the LWIR spectral region.

  4. Focal cortical dysplasia and epilepsy surgery.

    PubMed

    Lee, Sang Kun; Kim, Dong-Wook

    2013-12-01

    Focal cortical dysplasia (FCD) is the most commonly encountered developmental malformation that causes refractory epilepsy. With advances in neuroimaging techniques, in particular MRI, recent studies have revealed a higher prevalence of FCD than previously estimated and have improved the preoperative identification and classification of these abnormalities. However, MRI frequently does not show any abnormalities in patients with pathologically proven FCD. In this situation, functional neuroimaing such as FDG-PET and ictal SPECT can be helpful. FCD is thought to be intrinsically epileptogenic, because the dysplastic tissues contain aberrant neural networks that are highly susceptible to abnormal excitation. The response to the medical treatment of epilepsy has been documented as consistently poor. Therefore, surgical resection has been an important alternative treatment for patients with intractable epilepsy related to FCD. Incomplete resection of FCD has been consistently known to be a poor prognostic factor. However, the complete removal of FCD is often difficult because the demarcation of the lesion is frequently poor, and dysplastic tissues tend to be more extensive than is apparent on MRI. Evidence indicates that even patients with MRI abnormalities who have resective epilepsy surgery for FCD have worse surgical outcomes than those of patients who have surgery for other focal lesional epilepsy syndromes. Careful planning of evelauation using intracranial electrodes is necessary for successful epilepsy surgery. PMID:24649472

  5. CT appearance of focal fatty infiltration of the liver

    SciTech Connect

    Halvorsen, R.A.; Korobkin, M.; Ram, P.C.; Thompson, W.M.

    1982-08-01

    Focal fatty infiltration of the liver is an entity that may be confused with liver metastasis on computed tomography (CT). The imaging results and medical records of 16 patients with CT appearance suggestive of focal fatty liver were reviewed, three of whom had the simultaneous presence of metastitic liver disease. Focal fatty liver often has a distinctive appearance with CT, usually with a nonspherical shape, absence of mass effect, and density close to water. Liver metastases are usually round or oval, and unless cystic or necrotic, they have CT attenuation values closer to normal liver parenchyma than water. A radionuclide liver scan almost always resolves any confusion about the differential diagnosis of focal fatty liver: a well defined focus of photon deficiency is due to neoplasm rather than focal fatty infiltration. Sonography sometimes helps to confirm the CT impression, but may be misleading if the diagnosis of focal or diffuse fatty infiltration is not suspected before the examination.

  6. Oral focal mucinosis of palatal mucosa: A rare case report

    PubMed Central

    Bharti, Vipin; Singh, Jagmohan

    2012-01-01

    Oral focal mucinosis (OFM), an oral counterpart of cutaneous focal mucinosis, is a rare disease of unknown etiology. Its pathogenesis may be due to the overproduction of hyaluronic acid by a fibroblast, at the expense of collagen production, resulting in focal myxoid degeneration of the connective tissue, primarily affecting the mucosa overlying the bone. It has no distinctive clinical features, as the diagnosis is solely based on the histopathological features. This article reports of a 32-year-old female having the rare disease of oral focal mucinosis, involving the posterior palatal mucosa, and discusses its clinicopathological features and differential diagnosis of myxomatous lesions of the oral cavity. PMID:23230367

  7. Introduction of four different drive systems used in LAMOST focal plane

    NASA Astrophysics Data System (ADS)

    Wang, Guomin; Jiang, Xiang; Wang, Yuefei; Li, Guoping; Gu, Bozhong

    2006-06-01

    This paper describes four different drive systems adopted in LAMOST focal plane mechanism to achieve four movements: field derotation, focal plane attitude adjustment, focusing and move aside out of light path for optical checking. Different type drive systems, such as worm gear drive, spur gear drive, friction drive and direct drive, which were devised and used in telescopes in the past years, have their own inherent characteristics and their working conditions. According to feasibility, reliability, suitability and cost effective, friction drive, worm gear drive, ball screw drive and chain drive are selected to as the drive systems for the above four movements. The on-shop test results show that all the drive systems have met the design goals with the accuracy of image field derotation 0.45 arcsec, attitude adjustment 0.24 arcsec, focusing 2 microns and move aside 0.02mm.

  8. Multi-chroic Dual-Polarization Bolometric Focal Plane for Studies of the Cosmic Microwave Background

    NASA Astrophysics Data System (ADS)

    Suzuki, A.; Arnold, K.; Edwards, J.; Engargiola, G.; Ghribi, A.; Holzapfel, W.; Lee, A.; Meng, X.; Myers, M.; O'Brient, R.; Quealy, E.; Rebeiz, G.; Richards, P.

    2012-06-01

    We are developing multi-chroic antenna-coupled Transition Edge Sensor (TES) focal planes for Cosmic Microwave Background (CMB) polarimetry. In each pixel, a dual polarized sinuous antenna collects light over a two-octave frequency band. Each antenna couples to the telescope with a contacting silicon lens. The antenna couples the broadband RF signal to microstrip transmission lines, and then filter banks split the broadband signal into several frequency bands. A TES bolometer detects the power in each band and polarization. We will describe the design of this device and demonstrate its performance with optical data measured using prototype pixels. Our measurements show low ellipticity beams, low cross-polarization, and properly partitioned bands in banks of 2, 3, and 7 filters. Finally, we will describe how we will upgrade the Polarbear CMB experiment using the focal planes of these detectors to increase the experiment's mapping speed and its ability to discriminate between the CMB and polarized foregrounds.

  9. Solar-Driven Background Intensity Variations in a Focal Plane Array

    SciTech Connect

    Eyer, H.H.; Guillen, J.L.L.; Vittitoe, C.N.

    1998-12-03

    Portions of a series of end-of-life tests are described for a Sandia National Li~boratories- designed space-based sensor that utilizes a mercury-cadmium-telluride focal plane array. Variations in background intensity are consistent with the hypothesis that seasonal variations in solar position cause changes in the pattern of shadows falling across the compartment containing the optical elements, filter-band components, and focal plane array. When the sensor compartment is most fully illuminated by the sun, background intensities are large and their standard deviations tend to be large. During the winter season, when the compartment is most fully shadowed by surrounding structure, backgrounci intensities are small and standard deviations tend to be small. Details in the surrounding structure are speculated to produce transient shadows that complicate background intensifies as a function of time or of sensor position in orbit.

  10. Quantitative Characterization of Super-Resolution Infrared Imaging Based on Time-Varying Focal Plane Coding

    NASA Astrophysics Data System (ADS)

    Wang, X.; Yuan, Y.; Zhang, J.; Chen, Y.; Cheng, Y.

    2014-10-01

    High resolution infrared image has been the goal of an infrared imaging system. In this paper, a super-resolution infrared imaging method using time-varying coded mask is proposed based on focal plane coding and compressed sensing theory. The basic idea of this method is to set a coded mask on the focal plane of the optical system, and the same scene could be sampled many times repeatedly by using time-varying control coding strategy, the super-resolution image is further reconstructed by sparse optimization algorithm. The results of simulation are quantitatively evaluated by introducing the Peak Signal-to-Noise Ratio (PSNR) and Modulation Transfer Function (MTF), which illustrate that the effect of compressed measurement coefficient r and coded mask resolution m on the reconstructed image quality. Research results show that the proposed method will promote infrared imaging quality effectively, which will be helpful for the practical design of new type of high resolution ! infrared imaging systems.

  11. On-focal-plane processing techniques for infrared detectors for hyperspectral applications

    NASA Astrophysics Data System (ADS)

    Daniels, Arnold; Kaufman, Charles S.; Goodnough, Mark A.; Stineman, John A.

    1998-07-01

    A theoretical design of a reconfigurable detector array assembly is presented. This device is capable of changing the angular resolution and thermal sensitivity of the electro- optics array in real time. The apparent layout (i.e., size, spacing, and location) of the focal plane array detector elements is dynamic. This approach allows varying the instantaneous field-of-view as a function of the field angle, and combining adjacent spectral bands when poor atmospheric conditions are presented. This infrared reconfigurable hyperspectral focal plane array (IR-RHFPA) provides a way to get rid of some of the problems related to multi-spectral imagery sensors such as data rate, bow-tie effect, and sensitivity. Curves of spatial resolution versus field angle, and thermal sensitivity versus wavelength are obtained for the proper design and optimization of the IR-RHFPA. The potential operational configurations that best satisfy the system requirements are identified and displayed.

  12. Electro-optical system for scanning microscopy of extreme ultraviolet masks with a high harmonic generation source.

    PubMed

    Naulleau, Patrick P; Anderson, Christopher N; Anderson, Erik H; Andreson, Nord; Chao, Weilun; Choi, Changhoon; Goldberg, Kenneth A; Gullikson, Eric M; Kim, Seong-Sue; Lee, Donggun; Miyakawa, Ryan; Park, Jongju; Rekawa, Seno; Salmassi, Farhad

    2014-08-25

    A self-contained electro-optical module for scanning extreme ultraviolet (EUV) reflection microscopy at 13.5 nm wavelength has been developed. The system has been designed to work with stand-alone commercially available EUV high harmonic generation (HHG) sources through the implementation of narrowband harmonic selecting multilayers and off-axis elliptical short focal length zoneplates. The module has been successfully integrated into an EUV mask scanning microscope achieving diffraction limited imaging performance (84 nm point spread function). PMID:25321224

  13. IOP PUBLISHING JOURNAL OF OPTICS J. Opt. 15 (2013) 125716 (8pp) doi:10.1088/2040-8978/15/12/125716

    E-print Network

    Tyc, Tomas

    2013-01-01

    .1088/2040-8978/15/12/125716 Multi-focal spherical media and geodesic lenses in geometrical optics Martin Sarbort1 and Tom´as Tyc1-index lenses embedded in an optically homogeneous region and multi-focal absolute instruments that provide properties within geometrical optics. We mention spherical gradient-index lenses embedded in an optically

  14. Design of the focal plane array assembly for the Mars Observer/Visual and Infrared Mapping Spectrometer (MO/VIMS)

    NASA Technical Reports Server (NTRS)

    Niblack, Curtiss A.; Evans, Thomas G.; Toft, J. Brian

    1989-01-01

    A unique focal plane array (FPA) assembly combining both electronic and optical components in a single hermetically sealed hybrid package has been designed to meet the performance requirements imposed on the focal plane assembly in the Visual and Infrared Mapping Spectrometer (VIMS) for the Mars Observer (MO) mission. Inside the FPA package is a configuration of three multiplexed linear arrays containing 320 detector elements, a combination of Si and InSb, allowing continuous spectral coverage from 0.35 to 5.14 microns. An optical subassembly consisting of two spectral order-sorting filters with intrinsic field-of-view apertures requiring critical optical alignment is also internal to the hybrid. Several engineering issues arose during the MO/VIMS FPA development phase which had challenging design ramifications. FPA performance requirements, design approach, and critical issues are discussed.

  15. Image plane filters and adaptive optical systems

    NASA Astrophysics Data System (ADS)

    Seward, Anthony Joseph

    Shack-Hartmann sensors are the most commonly used wavefront sensors in adaptive optics applications today. There are problems when using Shack-Hartmann wavefront sensors in the presence of strong scintillation. This dissertation investigates the use of focal plane filters as wavefront sensors in adaptive optics systems. Both simulation and experiment are used to explore the characteristics of focal plane filter wavefront sensors, the conclusion being that they are a viable alternative to Shack-Hartmann wavefront sensors.

  16. Diagnosing malaria infected cells at the single cell level using focal plane array Fourier transform infrared imaging spectroscopy.

    PubMed

    Wood, Bayden R; Bambery, Keith R; Dixon, Matthew W A; Tilley, Leann; Nasse, Michael J; Mattson, Eric; Hirschmugl, Carol J

    2014-10-01

    New methods are needed to rapidly identify malaria parasites in blood smears. The coupling of a Focal Plane Array (FPA) infrared microscope system to a synchrotron light source at IRENI enables rapid molecular imaging at high spatial resolution. The technique, in combination with hyper-spectral processing, enables imaging and diagnosis of early stage malaria parasites at the single cell level in a blood smear. The method relies on the detection of distinct lipid signatures associated with the different stages of the malaria parasite and utilises resonant Mie extended multiplicative scatter correction to pre-process the spectra followed by full bandwidth image deconvolution to resolve the single cells. This work demonstrates the potential of focal plane technology to diagnose single cells in a blood smear. Brighter laboratory based infrared sources, optical refinements and higher sensitive detectors will soon see the emergence of focal plane array imaging in the clinical environment. PMID:25055796

  17. Generation of a spherical focal spot in a 4Pi focusing system through reversing the radiation of infinite biconical antenna

    NASA Astrophysics Data System (ADS)

    Yu, Yanzhong; Zhan, Qiwen

    2015-09-01

    A method of generating spherical focal spot is demonstrated through reversely propagating and tightly focusing the electric field at the pupil plane radiated from an infinite biconical antenna centered at the foci of two confocal high numerical aperture aplanatic objective lenses. The required incident field distribution at the pupil plane is found by solving the inverse problem of radiation from an infinite biconical antenna using the Richards-Wolf vectorial diffraction theory. Numerical simulations show that a focal spot of excellent spherical symmetry along with extremely low sidelobe (~4.72% of the peak) and diffraction limited spot size of 0.432? can be obtained in a 4Pi focusing system. It is also shown that the generated focal spot can be shifted along the optical axis while still maintaining its spherical shape and diffraction limited size through introducing a phase difference between the pupil illumination fields of the two objective lenses used in the 4Pi focusing system.

  18. Imaging performance and modeling of the Infrared Multi-Object Spectrometer focal reducer

    NASA Astrophysics Data System (ADS)

    Connelly, Joseph A.; Ohl, Raymond G., IV; Saha, Timo T.; Hadjimichael, Theo; Mentzell, John E.; Mink, Ronald G.; Hylan, Jason E.; Sparr, Leroy M.; Chambers, John; Hagopian, John J.; Greenhouse, Matthew A.; Winsor, Robert S.; MacKenty, John W.

    2003-03-01

    The Infrared Multi-Object Spectrometer (IRMOS) is a facility instrument for the Kitt Peak National Observatory 4 and 2.1 meter telescopes. IRMOS is a near-IR (0.8 2.5 ?m) spectrometer with low- to mid-resolving power (R = 300 3000). The IRMOS spectrometer produces simultaneous spectra of ~100 objects in its 2.8 x 2.0 arcmin field of view using a commercial MEMS multi-mirror array device (MMA) from Texas Instruments. The IRMOS optical design consists of two imaging subsystems. The focal reducer images the focal plane of the telescope onto the MMA field stop, and the spectrograph images the MMA onto the detector. We describe the breadboard subsystem alignment method and imaging performance of the focal reducer. This testing provides verification of the optomechanical alignment method and a measurement of near-angle scattered light due to mirror small-scale surface error. Interferometric measurements of subsystem wavefront error serve to verify alignment and are accomplished using a commercial, modified Twyman-Green laser unequal path interferometer. Image testing is then performed for the central field point. A mercury-argon pencil lamp provides the spectral line at 546.1 nm, and a CCD camera is the detector. We use the Optical Surface Analysis Code to predict the point-spread function and its effect on instrument slit transmission, and our breadboard test results validate this prediction. Our results show that scattered light from the subsystem and encircled energy is slightly worse than expected. Finally, we perform component level image testing of the MMA, and our results show that scattered light from the MMA is of the same magnitude as that of the focal reducer.

  19. Ocellar optics in nocturnal and diurnal bees and wasps.

    PubMed

    Warrant, Eric J; Kelber, Almut; Wallén, Rita; Wcislo, William T

    2006-12-01

    Nocturnal bees, wasps and ants have considerably larger ocelli than their diurnal relatives, suggesting an active role in vision at night. In a first step to understanding what this role might be, the morphology and physiological optics of ocelli were investigated in three tropical rainforest species - the nocturnal sweat bee Megalopta genalis, the nocturnal paper wasp Apoica pallens and the diurnal paper wasp Polistes occidentalis - using hanging-drop techniques and standard histological methods. Ocellar image quality, in addition to lens focal length and back focal distance, was determined in all three species. During flight, the ocellar receptive fields of both nocturnal species are centred very dorsally, possibly in order to maximise sensitivity to the narrow dorsal field of light that enters through gaps in the rainforest canopy. Since all ocelli investigated had a slightly oval shape, images were found to be astigmatic: images formed by the major axis of the ocellus were located further from the proximal surface of the lens than images formed by the minor axis. Despite being astigmatic, images formed at either focal plane were reasonably sharp in all ocelli investigated. When compared to the position of the retina below the lens, measurements of back focal distance reveal that the ocelli of Megalopta are highly underfocused and unable to resolve spatial detail. This together with their very large and tightly packed rhabdoms suggests a role in making sensitive measurements of ambient light intensity. In contrast, the ocelli of the two wasps form images near the proximal boundary of the retina, suggesting the potential for modest resolving power. In light of these results, possible roles for ocelli in nocturnal bees and wasps are discussed, including the hypothesis that they might be involved in nocturnal homing and navigation, using two main cues: the spatial pattern of bright patches of daylight visible through the rainforest canopy, and compass information obtained from polarised skylight (from the setting sun or the moon) that penetrates these patches. PMID:18089077

  20. Idiopathic focal segmental glomerulosclerosis and HLA antigens.

    PubMed

    Gerbase-DeLima, M; Pereira-Santos, A; Sesso, R; Temin, J; Aragão, E S; Ajzen, H

    1998-03-01

    The objective of the present study was to investigate a possible association between HLA class II antigens and idiopathic focal segmental glomerulosclerosis (FSGS). HLA-A, -B, -DR and -DQ antigens were determined in 19 Brazilian patients (16 white subjects and three subjects of Japanese origin) with biopsy-proven FSGS. Comparison of the HLA antigen frequencies between white patients and white local controls showed a significant increase in HLA-DR4 frequency among FSGS patients (37.7 vs 17.2%, P < 0.05). In addition, the three patients of Japanese extraction, not included in the statistical analysis, also presented HLA-DR4. In conclusion, our data confirm the association of FSGS with HLA-DR4 previously reported by others, thus providing further evidence for a role of genes of the HLA complex in the susceptibility to this disease. PMID:9698788

  1. Focal cemento-osseous dysplasia of mandible.

    PubMed

    Cankaya, Abdülkadir Burak; Erdem, Mehmet Ali; Olgac, Vakur; Firat, Deniz Refia

    2012-01-01

    Fibro-osseous lesions are disturbances in bone metabolism in which normal bone is replaced by a connective tissue matrix that then gradually develops into cemento-osseous tissue. Typically, the lesion is asymptomatic and is detected on routine radiographic examination. Radiologically, this lesion has three stages of maturation: pure radiolucent, radiopaque/mixed radiolucent, and radiopaque appearance. During these stages the lesion can be misdiagnosed. In this case report a 69-year- old patient with a a complaint of painless swelling of the left mandibular molar and premolar area is presented along with a review of the differential diagnoses considered in order to reach a final diagnosis of focal cemento-osseous dysplasia. PMID:22948991

  2. Focal adhesion kinase function in neuronal development.

    PubMed

    Navarro, Ana I; Rico, Beatriz

    2014-08-01

    During the development and maturation of the adult nervous system, several consecutive events, from neural induction to axon-dendrite arborization and synapse formation, contribute to the final exquisite specificity of neuronal networks. To accomplish this precise and healthy brain architecture, a coordinated rearrangement of the cytoskeleton in response to extracellular cues is essential. In this review, we propose focal adhesion kinase (FAK) as a key intracellular component for this command, and summarize different studies that support this hypothesis. We will discuss how FAK interacts with different extracellular molecules and the cytoskeleton and how FAK functions as a sort of "orchestra conductor" coordinating a broad range of signaling pathways during neuronal motility. PMID:24705242

  3. Compressive Optical MONTAGE Photography David J. Bradya

    E-print Network

    Pitsianis, Nikos P.

    , holographic and 3D optical elements for focal plane remapping and embedded algorithms for image formation optical and electronic optimization for 3D sensing, tracking, feature-specific imaging and conformal array of Engineering, Duke University, Durham, NC 27708 b Digital Optics Corporation, 9815 David Taylor Drive

  4. Focal ratio degradation in lightly fused hexabundles

    NASA Astrophysics Data System (ADS)

    Bryant, J. J.; Bland-Hawthorn, J.; Fogarty, L. M. R.; Lawrence, J. S.; Croom, S. M.

    2014-02-01

    We are now moving into an era where multi-object wide-field surveys, which traditionally use single fibres to observe many targets simultaneously, can exploit compact integral field units (IFUs) in place of single fibres. Current multi-object integral field instruments such as Sydney-AAO Multi-object Integral field spectrograph have driven the development of new imaging fibre bundles (hexabundles) for multi-object spectrographs. We have characterized the performance of hexabundles with different cladding thicknesses and compared them to that of the same type of bare fibre, across the range of fill fractions and input f-ratios likely in an IFU instrument. Hexabundles with 7-cores and 61-cores were tested for focal ratio degradation (FRD), throughput and cross-talk when fed with inputs from F/3.4 to >F/8. The five 7-core bundles have cladding thickness ranging from 1 to 8 ?m, and the 61-core bundles have 5 ?m cladding. As expected, the FRD improves as the input focal ratio decreases. We find that the FRD and throughput of the cores in the hexabundles match the performance of single fibres of the same material at low input f-ratios. The performance results presented can be used to set a limit on the f-ratio of a system based on the maximum loss allowable for a planned instrument. Our results confirm that hexabundles are a successful alternative for fibre imaging devices for multi-object spectroscopy on wide-field telescopes and have prompted further development of hexabundle designs with hexagonal packing and square cores.

  5. A low cost uncooled focal plane array test system

    NASA Astrophysics Data System (ADS)

    Li, Yingwen; Yi, Xinjian; He, Zhaoxiang; Luo, Yan

    2003-04-01

    The commercial test equipments from Pulse Instruments, Lumitron and Electro Optical Industries Inc. are very expensive. So, we proposed a new method of very low cost test system for testing the non-uniformity and signal/noise (S/N) and other characteristics of the uncooled focal plane array (UFPA). It uses complex programmable logic device to generate the necessary pulse for the UFPA and the low noise low dropout micropower regulator to obtain the low noise bias. A proportional-integral-differential controlled thermal electrical cooler based on micro-processor unit stabilizes the UFPA. The National Instruments 6111E Data Acquisition Card is used to convert the analog output of UFPA into digital signal into computer. Its 12-bits conversion capability provides sufficient accuracy for evaluating the S/N ratio and non-uniformity of 128×128 pixels UFPA. Labview is used to analyze the signal. The instrument is fast and convenient to adapt the system to other types of UFPA. Further discussion is presented to determine factors that affect the accuracy of the tester.

  6. Segmented mirror phasing using the focal-plane intensity.

    PubMed

    Dente, Gregory C; Tilton, Michael L

    2012-01-20

    We develop a method for subaperture piston phase retrieval in a telescope using a segmented primary mirror. We assume that the mirror subapertures are arranged on a two-dimensional lattice, and in addition, the separate subaperture point-spread functions are focused and overlapped on the focal plane. Therefore, the residual errors are the subaperture piston phase errors, represented as a phasor, a unit modulus complex number, for each subaperture. Under these conditions, we find considerable simplicity in the calculated optical transfer function (OTF) at special subaperture lattice spatial frequencies. We then construct a phasor-based error function based on the modulus squared of the difference between the measured OTF and the calculated OTF. The remaining steps in our piston phase retrieval algorithms are developed by calculating the error-function variation, with respect to each phasor element. The resulting equations for the error gradient are then used iteratively, in a phasor-based algorithm, to find the minimum of the error function. In the applications, we simulate photon-noise-limited piston retrieval for a segmented primary with 18 hexagonal subapertures. When we invoke phase diversity, the piston retrievals prove unique and accurate. PMID:22270655

  7. Design of a focal plane array with analog neural preprocessing

    NASA Astrophysics Data System (ADS)

    Koren, Ivo; Dohndorf, Juergen; Schluessler, Jens-Uwe; Werner, Joerg; Kroenig, Arndt; Ramacher, Ulrich

    1996-12-01

    The design of a CMOS focal plane array with 128 by 128 pixels and analog neural preprocessing is presented. Optical input to the array is provided by substrate-well photodiodes. A two-dimensional neural grid wIth next- neighbor connectivity, implemented as differential current- mode circuit, is capable of spatial low-pass filtering combined with contrast enhancement or binarization. The gain, spatial filter and nonlinearity parameters of the neural network are controlled externally using analog currents. This allows the multipliers and sigmoid transducers to be operated in weak inversion for a wide parameter sweep range as well as in moderate or strong inversion for a larger signal to pattern-noise ratio. The cell outputs are sequentially read out by an offset compensated differential switched-capacitor multiplexer with column preamplifiers. The analog output buffer is designed for pixel rates up to 1 pixel/microsecond and 2 by 100 pF load capacitance. All digital clocks controlling the analog data path are generated on-chip. The clock timing is programmable via a serial computer interface. Using 1 micrometer double-poly double-metal CMOS process, one pixel cell occupies 96 by 96 micrometer2 and the total chip size is about 2.3 cm2. Operating the neural network in weak inversion, the power dissipation of the analog circuitry is less than 100 mW.

  8. Multicolor focal plane array detector technology: a review

    NASA Astrophysics Data System (ADS)

    Abedin, M. Nurul; Refaat, Tamer F.; Zawodny, Joseph M.; Sandford, Steve P.; Singh, Upendra N.; Bandara, Sumith V.; Gunapala, Sarath D.; Bhat, Ishwara; Barnes, Norman P.

    2003-11-01

    A major concern today is to accurately measure CO2, O3, H2O, and CH4 in the atmosphere for the prediction of climate and weather. These measurements are critical for understanding the Earth's atmosphere, atmospheric chemistry, and systemic forcing driving climactic changes. For these measurements, detectors with high quantum efficiency and near background limited performance detectivity over a wide wavelength range are necessary. In this article, we will review the state-of-the-art single and multicolor detector technologies in a wide spectral-range, for use in space-based and airborne remote sensing applications. Simultaneous detection in multi-wavelength bands with a single focal plane array (FPA) will result in reduction or elimination of heavy and complex optical components now required for wavelength differentiation in atmospheric remote sensors leading to smaller, lighter, simpler instruments with higher performance. Discussions are focused on current and the most recently developed FPA in addition to emphasizing future development in UV-to-Far infrared multicolor FPA detectors for next generation space-based instruments to measure water vapor and greenhouse gases. This novel detector component will make instruments designed for these critical measurements more efficient while reducing complexity and associated electronics and weight. Finally, we will discuss the on-going detector technology efforts at NASA Langley Research Center (LaRC), Jet Propulsion Laboratory (JPL), and Rensselaer Polytechnic Institute (RPI).

  9. Osteogenic lineage restriction by osteoprogenitors cultured on nanometric grooved surfaces: the role of focal adhesion maturation.

    PubMed

    Cassidy, John W; Roberts, Jemma N; Smith, Carol-Anne; Robertson, Mary; White, Kate; Biggs, Manus J; Oreffo, Richard O C; Dalby, Matthew J

    2014-02-01

    The differentiation of progenitor cells is dependent on more than biochemical signalling. Topographical cues in natural bone extracellular matrix guide cellular differentiation through the formation of focal adhesions, contact guidance, cytoskeletal rearrangement and ultimately gene expression. Osteoarthritis and a number of bone disorders present as growing challenges for our society. Hence, there is a need for next generation implantable devices to substitute for, or guide, bone repair in vivo. Cellular responses to nanometric topographical cues need to be better understood in vitro in order to ensure the effective and efficient integration and performance of these orthopedic devices. In this study, the FDA-approved plastic polycaprolactone was embossed with nanometric grooves and the response of primary and immortalized osteoprogenitor cells observed. Nanometric groove dimensions were 240 nm or 540 nm deep and 12.5 ?m wide. Cells cultured on test surfaces followed contact guidance along the length of groove edges, elongated along their major axis and showed nuclear distortion; they formed more focal complexes and lower proportions of mature adhesions relative to planar controls. Down-regulation of the osteoblast marker genes RUNX2 and BMPR2 in primary and immortalized cells was observed on grooved substrates. Down-regulation appeared to directly correlate with focal adhesion maturation, indicating the involvement of ERK 1/2 negative feedback pathways following integrin-mediated FAK activation. PMID:24252447

  10. LSST Camera Optics Design

    SciTech Connect

    Riot, V J; Olivier, S; Bauman, B; Pratuch, S; Seppala, L; Gilmore, D; Ku, J; Nordby, M; Foss, M; Antilogus, P; Morgado, N

    2012-05-24

    The Large Synoptic Survey Telescope (LSST) uses a novel, three-mirror, telescope design feeding a camera system that includes a set of broad-band filters and three refractive corrector lenses to produce a flat field at the focal plane with a wide field of view. Optical design of the camera lenses and filters is integrated in with the optical design of telescope mirrors to optimize performance. We discuss the rationale for the LSST camera optics design, describe the methodology for fabricating, coating, mounting and testing the lenses and filters, and present the results of detailed analyses demonstrating that the camera optics will meet their performance goals.

  11. DESIGNATION OF FOCAL VERTEBRATE SPECIES FOR THE LAKE TAHOE BASIN

    E-print Network

    Standiford, Richard B.

    APPENDIX L DESIGNATION OF FOCAL VERTEBRATE SPECIES FOR THE LAKE TAHOE BASIN #12;APPENDIX L DESIGNATION OF FOCAL VERTEBRATE SPECIES FOR THE LAKE TAHOE BASIN Patricia N. Manley and Matthew D. Schlesinger status. The criteria used for determining candidate species differed among vertebrate groups based

  12. Telangiectatic focal nodular hyperplasia: a variant of hepatocellular adenoma

    Microsoft Academic Search

    Valerie Paradis; Asmae Benzekri; Delphine Dargère; Ivan Bièche; Ingrid Laurendeau; Valerie Vilgrain; Jacques Belghiti; Michel Vidaud; Claude Degott; Pierre Bedossa

    2004-01-01

    Background & Aims: “Telangiectatic focal nodular hyperplasia” designate atypical lesions considered as variants of focal nodular hyperplasia (FNH). However, because “telangiectatic FNH” share several morphologic patterns with hepatocellular adenomas, classification of such lesions deserve further clarification. Therefore, the aim of the present study was to reconsider the classification of telangiectatic FNH with the help of a molecular approach. Methods: Ten

  13. Quantum Dot Focal Plane Array with Plasmonic Resonator Sanjay Krishna

    E-print Network

    Krishna, Sanjay

    . Various optoelectronic devices such as lasers, detectors, filters and solar cells are expected to benefitQuantum Dot Focal Plane Array with Plasmonic Resonator Sanjay Krishna Electrical and Computer structures with quantum dot focal plane arrays. Keywords: infrared detectors, quantum dots-in-a-well (DWELL

  14. RESEARCH Open Access Focal Laser Ablation of Prostate Cancer

    E-print Network

    Paris-Sud XI, Université de

    RESEARCH Open Access Focal Laser Ablation of Prostate Cancer: Numerical Simulation of Temperature between simulation and in vivo experiments of FLA for prostate cancer. Simulation is a promising planning surgical method. Keywords: Prostate cancer focal laser ablation, thermal damage, bioheat transfer

  15. Focally spared area of fatty liver caused by arterioportal shunt

    SciTech Connect

    Arita, Takeshi; Matsunaga, Naofumi [Yamaguchi Univ. School of Medicine (Japan)] [Yamaguchi Univ. School of Medicine (Japan); Honma, Yutaka [Shimonoseki City Hospital, Yamaguchi (Japan)] [and others] [Shimonoseki City Hospital, Yamaguchi (Japan); and others

    1996-05-01

    We describe a case with a focally spared area in fatty liver caused by arterioportal shunt. Furthermore, we discuss the cause of the focally spared area related to a localized dilution or reduction in portal blood flow. 13 refs., 1 fig.

  16. Focal shift of partially polarized Gaussian Schell-model beams

    Microsoft Academic Search

    L. e. i. Wang; Baida Lu

    2003-01-01

    A detailed study of the focal shift of partially polarized Gaussian Schell-model (PGSM) beams is made on the basis of the beam coherence-polarization (BCP) matrix approach. It is shown that, apart from the Fresnel number and truncation parameter, the focal shift of PGSM beams depends on the angle of polarizer and the ratio of degree of spatial coherence.

  17. Focal cortical dysplasia: neuropathological subtypes, EEG, neuroimaging and surgical outcome

    Microsoft Academic Search

    L. Tassi; N. Colombo; R. Garbelli; S. Francione; G. Lo Russo; R. Mai; F. Cardinale; M. Cossu; A. Ferrario; C. Galli; M. Bramerio; A. Citterio; R. Spreafico

    2002-01-01

    Summary Since the original description by Taylor, the term focal cortical dysplasia has been used to refer to a wide range of alterations of the cortical mantle. More recently, these conditions have been described from neuroimaging, neuropathological and genetic stand- points, generating several classifications. It is widely recognized that these classifications are unsatisfactory. We propose a simplified classification of focal

  18. Focal Manual for CAI Coding on the TSS/8 System.

    ERIC Educational Resources Information Center

    Kirbs, H. Dewey; And Others

    Basic information is provided in this manual for coding drill-and-practice CAI (computer-assisted instruction) applications in the language FOCAL (Formulating On-line Calculations in Algebraic Language). This language is available on the Digital Equipment Corporation Time-Sharing 8 system (TSS/8). While FOCAL is oriented toward solution of…

  19. Hepatic focal nodular hyperplasia: angiography, CT, sonography, and scintigraphy

    Microsoft Academic Search

    J. V. Rogers; L. A. Mack; P. C. Freeny; M. L. Johnson; P. J. Sones

    1981-01-01

    Eleven patients with focal nodular hyperplasia of the liver underwent a combination of radiologic procedures, including sonography, computed tomography (CT), hepatic scintigraphy, and angiography. This paper describes the radiologic findings in this group of patients and reviews the current literature. In the present series, sonography was the most sensitive (100%) method for detection of focal nodular hyperplasia, while CT was

  20. Energy Reconstruction with the Sweeper Magnet Focal Plane Detector

    Microsoft Academic Search

    George Hitt; Michael Thoennessen; Nathan Frank; Matt Cooper; A. M. Vander Molen; Brian Nett

    2002-01-01

    The Sweeper Magnet Focal Plane Detector project is a collaboration of the National High Magnetic Field Laboratory (NHMFL) at Florida State University and the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The NHMFL will construct the Sweeper Magnet, a large C-type magnet necessary for the bending of rigid nuclear beams. The NSCL will build the Focal Plane Detectors

  1. Chronic focal seizure disorder as a manifestation of intracranial iophendylate.

    PubMed

    Pascuzzi, R M; Roos, K L; Scott, J A

    1988-01-01

    A 46-year-old woman developed focal seizures 10-15 years following iophendylate myelography. Focal epileptogenic abnormalities on electroencephalogram corresponded to the localization of residual iophendylate in the right sylvian fissure. Intracranial iophendylate may have produced chronic meningeal reaction leading to cortical irritation and a chronic seizure disorder. PMID:3131136

  2. Imaging Modalities for Focal Nodular Hyperplasia and Hepatocellular Adenoma

    Microsoft Academic Search

    Jacomina W. van den Esschert; Thomas M. van Gulik; Saffire S. K. S. Phoa

    2010-01-01

    Background\\/Aims: There are several imaging modalities available for the detection of focal liver lesions. Differentiation between focal nodular hyperplasia (FNH) and hepatocellular adenoma (HCA) is important because of the consequences for management. However, differentiation based on imaging alone still shows limitations. Methods: We reviewed the literature for typical features of FNH and HCA on radiologic and nuclear imaging with emphasis

  3. Relativistic Length Agony Continued

    NASA Astrophysics Data System (ADS)

    Redzic, D. V.

    2014-06-01

    We made an attempt to remedy recent confusing treatments of some basic relativistic concepts and results. Following the argument presented in an earlier paper (Redzic 2008b), we discussed the misconceptions that are recurrent points in the literature devoted to teaching relativity such as: there is no change in the object in Special Relativity, illusory character of relativistic length contraction, stresses and strains induced by Lorentz contraction, and related issues. We gave several examples of the traps of everyday language that lurk in Special Relativity. To remove a possible conceptual and terminological muddle, we made a distinction between the relativistic length reduction and relativistic FitzGerald-Lorentz contraction, corresponding to a passive and an active aspect of length contraction, respectively; we pointed out that both aspects have fundamental dynamical contents. As an illustration of our considerations, we discussed briefly the Dewan-Beran-Bell spaceship paradox and the 'pole in a barn' paradox.

  4. Energy Input per Unit Length - High Accuracy Kinematic Metrology in Laser Material Processing

    NASA Astrophysics Data System (ADS)

    Franz, Christoph; Abels, Peter; Rolser, Raphael; Becker, Michael

    Laser material processes require constant energy input per unit length. Besides focal z-position, spot size, laser power and other process parameters, the relative travel speed (feed rate) of the laser spot on the work piece has the highest influence on the resulting energy input per unit length. In this paper a new metrology method is introduced, which enables users in industry and research to measure the real travel speed of the laser spot and the resulting contour of the trajectory.

  5. Afocal Optical Flow Sensor for Reducing Vertical Height Sensitivity in Indoor Robot Localization and Navigation

    PubMed Central

    Yi, Dong-Hoon; Lee, Tae-Jae; Cho, Dong-Il “Dan”

    2015-01-01

    This paper introduces a novel afocal optical flow sensor (OFS) system for odometry estimation in indoor robotic navigation. The OFS used in computer optical mouse has been adopted for mobile robots because it is not affected by wheel slippage. Vertical height variance is thought to be a dominant factor in systematic error when estimating moving distances in mobile robots driving on uneven surfaces. We propose an approach to mitigate this error by using an afocal (infinite effective focal length) system. We conducted experiments in a linear guide on carpet and three other materials with varying sensor heights from 30 to 50 mm and a moving distance of 80 cm. The same experiments were repeated 10 times. For the proposed afocal OFS module, a 1 mm change in sensor height induces a 0.1% systematic error; for comparison, the error for a conventional fixed-focal-length OFS module is 14.7%. Finally, the proposed afocal OFS module was installed on a mobile robot and tested 10 times on a carpet for distances of 1 m. The average distance estimation error and standard deviation are 0.02% and 17.6%, respectively, whereas those for a conventional OFS module are 4.09% and 25.7%, respectively. PMID:25985164

  6. Afocal optical flow sensor for reducing vertical height sensitivity in indoor robot localization and navigation.

    PubMed

    Yi, Dong-Hoon; Lee, Tae-Jae; Cho, Dong-Il

    2015-01-01

    This paper introduces a novel afocal optical flow sensor (OFS) system for odometry estimation in indoor robotic navigation. The OFS used in computer optical mouse has been adopted for mobile robots because it is not affected by wheel slippage. Vertical height variance is thought to be a dominant factor in systematic error when estimating moving distances in mobile robots driving on uneven surfaces. We propose an approach to mitigate this error by using an afocal (infinite effective focal length) system. We conducted experiments in a linear guide on carpet and three other materials with varying sensor heights from 30 to 50 mm and a moving distance of 80 cm. The same experiments were repeated 10 times. For the proposed afocal OFS module, a 1 mm change in sensor height induces a 0.1% systematic error; for comparison, the error for a conventional fixed-focal-length OFS module is 14.7%. Finally, the proposed afocal OFS module was installed on a mobile robot and tested 10 times on a carpet for distances of 1 m. The average distance estimation error and standard deviation are 0.02% and 17.6%, respectively, whereas those for a conventional OFS module are 4.09% and 25.7%, respectively. PMID:25985164

  7. Combined Scanning Transmission Electron Microscopy Tilt- and Focal Series

    SciTech Connect

    Dahmen, Tim [German Research Center for Artificial Intelligence (DFKI), Germany] [German Research Center for Artificial Intelligence (DFKI), Germany; Baudoin, Jean-Pierre G [ORNL] [ORNL; Lupini, Andrew R [ORNL] [ORNL; Kubel, Christian [Karlsruhe Institute of Technology, Leopoldshafen, Germany] [Karlsruhe Institute of Technology, Leopoldshafen, Germany; Slusallek, Phillip [German Research Center for Artificial Intelligence (DFKI), Germany] [German Research Center for Artificial Intelligence (DFKI), Germany; De Jonge, Niels [ORNL] [ORNL

    2014-01-01

    In this study, a combined tilt- and focal series is proposed as a new recording scheme for high-angle annular dark-field scanning transmission electron microscopy (STEM) tomography. Three-dimensional (3D) data were acquired by mechanically tilting the specimen, and recording a through-focal series at each tilt direction. The sample was a whole-mount macrophage cell with embedded gold nanoparticles. The tilt focal algebraic reconstruction technique (TF-ART) is introduced as a new algorithm to reconstruct tomograms from such combined tilt- and focal series. The feasibility of TF-ART was demonstrated by 3D reconstruction of the experimental 3D data. The results were compared with a conventional STEM tilt series of a similar sample. The combined tilt- and focal series led to smaller missing wedge artifacts, and a higher axial resolution than obtained for the STEM tilt series, thus improving on one of the main issues of tilt series-based electron tomography.

  8. Hybrid refractive/diffractive optical system design for light and compact uncooled longwave infrared imager

    NASA Astrophysics Data System (ADS)

    Wang, Hu; Bai, Yu; Luo, Jianjun

    2012-10-01

    Compares with traditional optics,the difractive optical element(DOE) has unique property of minus dispersion.The special state can be used in the optical system to improve performance,lighten weight and reduce volume effectively.In the paper,an infrared optical system with DOE for LWIR thermal imager is proposed.The primary optical parameters of thermal imager are wavelength range 8.0- 12.0?m,effective focal length (EFL) 150 mm,f/numbe 1.0 and field of view 8.58 degrees.The system uses uncooled infrared detector with 320×240 pixels and 45?m pixel size. The f/number matches the sensitivity range of detector array. The infrared optical system is designed by CODE-V optical design software.It is consisted of two lens,the materials of the two lenses are Germanium.The DOE is fabricated on the convex of the first lens and it can be fabricated by diamond turning technology.The imaging quafity of the optical system approached to diffraction limit.The value of modulation transfer function (MTF) at Nyquist frequency(11lp/mm) is great than 0.78.

  9. Selecting a high-power fiber-optic laser beam delivery system

    SciTech Connect

    Hunter, B.V. [LightPath Technologies, Inc., Albuquerque, NM (United States); Leong, K.H. [Argonne National Lab., IL (United States); Miller, C.B.; Golden, J.F.; Glesias, R.D.; Laverty, P.J. [U.S. Laser Corp., Wyckoff, NJ (United States)

    1996-10-01

    Multimode optical fibers enable efficient flexible laser beam delivery but at a loss in the quality of the delivered beam. The fiber-optic beam delivery system effectiveness is strengthened by the optimal selection of its components not only for minimizing beam quality degradation but also for robustness. Smaller fibers tend to produce less degradation to beam quality but the minimum usable fiber size is limited by the quality of the laser beam, focusing optic, and the numerical aperture of the fiber. Selection of appropriate fiber type is important because the characteristics of the output beam enhance or degrade the utility of the fiber-optic-delivered beam for different applications. The other components of the beam delivery system also impact performance. High-power handling requires high- quality fiber end-face finish and special connectors that can withstand back-reflections. Recent developments in optical materials allow manufacture of very low aberration optics useful for short focal length lenses in output optics. Harnessing the power of a high- power laser requires that knowledgeable and prudent choices be made when selecting the laser and its beam delivery system. We will focus on issues relevant to understanding and specifying a fiber-optic beam delivery system and provide guidelines for specifying a system. Data obtained with high power Nd:YAG lasers will be used as examples.

  10. Back focal plane imaging of Tamm plasmons and their coupled emission

    PubMed Central

    Chen, Yikai; Zhang, Douguo; Qiu, Dong; Zhu, Liangfu; Yu, Sisheng; Yao, Peijun; Wang, Pei; Ming, Hai; Badugu, Ramachandram; Lakowicz, Joseph R.

    2015-01-01

    The unique optical properties of TPs – such as flexible wavevector matching conditions including in-plane wavevector within the light line, existing both S- and P-polarized TPs and ability of populating with KR and RK illuminations – facilitate them for direct optical excitation. The Tamm plasmon Coupled emission (TPCE) from a combined photonic-plasmonic structure sustaining both surface plasmons (SPs) and Tamm plasmons (TPs) is described. The sensitivity of TPCE to the emission wavelength and polarization is examined with back focal plane imaging and verified with the numerical calculations. The results reveal that the excited probe can couple with both TPs and SPs, resulting in SPCE and TPCE, respectively. The TPCE angle is strongly dependent on the wavelength allowing for spectral resolution using different observation angles. These Tamm structures provide a new tool to control the optical emission from dye molecules and have many potential applications in fluorescence based-sensing and imaging. PMID:25893010

  11. Real-time dynamic coupling of GPC-enhanced diffraction-limited focal spots

    NASA Astrophysics Data System (ADS)

    Villangca, Mark; Bañas, Andrew; Kopylov, Oleksii; Palima, Darwin; Glückstad, Jesper

    2015-03-01

    We have previously demonstrated on-demand dynamic coupling of an optically manipulated wave-guided optical waveguide (WOW) using diffractive techniques on a "point and shoot" approach. In this work, the generation of the coupling focal spots is done in real-time following the position of the WOW. Object-tracking routine has been added in the trapping program to get the position of the WOW. This approach allows continuous coupling of light through the WOWs which may be useful in some application. In addition, we include a GPC light shaper module in the holography setup to efficiently illuminate the spatial light modulator (SLM). The ability to switch from on-demand to continuous addressing with efficient illumination leverages our WOWs for potential applications in stimulation and nonlinear optics.

  12. Measurement of subpicosecond electron pulse length

    SciTech Connect

    Lihn, Hung chi

    1996-04-01

    A new frequency-resolved bunch-length measuring system has been developed at the Stanford SUNSHINE facility to characterize subpicosecond electron pulses. Using a far-infrared Michelson interferometer, this method measures the spectrum of coherent transition radiation emitted from electron bunches through optical autocorrelation. The electron bunch length is obtained from the measurement with a simple and systematic analysis which includes interference effects caused by the beam splitter. This method demonstrates subpicosecond resolving power that cannot be achieved by existing time-resolved methods. The principle of this method and experimental results are discussed.

  13. Measurement of subpicosecond electron bunch lengths

    SciTech Connect

    Lihn, Hung-chi; Bocek, D.; Kung, P.; Settakorn, C.; Wiedemann, H.

    1995-11-01

    A new frequency-resolved bunch-length measuring system has been developed at the Stanford SUNSHINE facility suitable for subpicosecond electron bunches. This method utilizes a far-infrared Michelson interferometer to measure coherent transition radiation emitted from electron bunches through optical auto-correlation. A simple and systematic way has also been developed to include interference effects caused by the beam splitter, so the electron bunch length can be easily obtained from the measurement. This autocorrelation method demonstrates subpicosecond resolving power that cannot be achieved by existing time-resolved methods.

  14. Low-coherent WDM reflectometry for accurate fiber length monitoring

    Microsoft Academic Search

    R. Hui; J. Thomas; C. Allen; B. Fu; S. Gao

    2003-01-01

    A fiber-optic low-coherent reflectometer was developed to accurately monitor fiber length variation. A large length-coverage range was obtained by using a fiber Bragg grating array in a wavelength-division-multiplexing configuration. The polarization mismatch-induced signal fading was eliminated by applying a polarization spreading technique at the optical receiver and, therefore, no active polarization adjustment was necessary for long-term measurement.

  15. Role of Soy Phytoestrogens Genistein and Daidzein in Focal Adhesion Assembly and Focal Adhesion Kinase Activity in Breast Cancer Cells

    Microsoft Academic Search

    Nicolas G. Azios; Suranganie F. Dharmawardhane

    Summary Recently, our laboratory and others have shown that estrogen receptor (ER) ? ?negative (-) breast cancer (BC) cells respond to estrogenic compounds via rapid signaling mechanisms. To understand the role of soy phytoestrogens in BC cell invasion, we analyzed focal complex formation and focal adhesion kinase (FAK) activity, as detected by phospho-specific anti-FAK antibodies to tyrosine residues 397 or

  16. Lengths of Ladybugs

    NSDL National Science Digital Library

    Utah LessonPlans

    2012-09-18

    In this math lesson, learners explore the concept of using units to measure length. Learners first read "Ladybug on the Move" by Richard Fowler and measure the distance the ladybug travels on each page using yarn. Next, learners make their own "Go Ladybug Go!" books and use lima beans and a ladybug ruler to make and record measurements.

  17. Document Length Normalization.

    ERIC Educational Resources Information Center

    Singhal, Amit; And Others

    1996-01-01

    Describes a study that investigated document retrieval relevance based on document length in an experimental text collection. Topics include term weighting and document ranking, retrieval strategies such as the vector-space cosine match, and a modified technique called the pivoted cosine normalization. (LRW)

  18. Reversible variable length codes

    Microsoft Academic Search

    Y. Takishima; M. Wada; H. Murakami

    1995-01-01

    Proposes some reversible variable length codes (RVLCs) which can be decoded instantaneously both in the forward and backward directions and have high transmission efficiency. These codes can be used, for example, in the backward reconstruction of video signals from the data last received when some signal is lost midway in the transmission. Schemes for a symmetrical RVLC requiring only a

  19. Mappability and read length

    PubMed Central

    Li, Wentian; Freudenberg, Jan

    2014-01-01

    Power-law distributions are the main functional form for the distribution of repeat size and repeat copy number in the human genome. When the genome is broken into fragments for sequencing, the limited size of fragments and reads may prevent an unique alignment of repeat sequences to the reference sequence. Repeats in the human genome can be as long as 104 bases, or 105 ? 106 bases when allowing for mismatches between repeat units. Sequence reads from these regions are therefore unmappable when the read length is in the range of 103 bases. With a read length of 1000 bases, slightly more than 1% of the assembled genome, and slightly less than 1% of the 1 kb reads, are unmappable, excluding the unassembled portion of the human genome (8% in GRCh37/hg19). The slow decay (long tail) of the power-law function implies a diminishing return in converting unmappable regions/reads to become mappable with the increase of the read length, with the understanding that increasing read length will always move toward the direction of 100% mappability. PMID:25426137

  20. Optics, illumination, and image sensing for machine vision III; Proceedings of the Meeting, Cambridge, MA, Nov. 8, 9, 1988

    SciTech Connect

    Svetkoff, D.J.

    1989-01-01

    Various papers on optics, illumination, and image sensing for machine vision are presented. Some of the optics discussed include: illumination and imaging of moving objects, strobe illumination systems for machine vision, optical collision timer, new electrooptical coordinate measurement system, flexible and piezoresistive touch sensing array, selection of cameras for machine vision, custom fixed-focal length versus zoom lenses, performance of optimal phase-only filters, minimum variance SDF design using adaptive algorithms, Ho-Kashyap associative processors, component spaces for invariant pattern recognition, grid labeling using a marked grid, illumination-based model of stochastic textures, color-encoded moire contouring, noise measurement and suppression in active 3-D laser-based imaging systems, structural stereo matching of Laplacian-of-Gaussian contour segments for 3D perception, earth surface recovery from remotely sensed images, and shape from Lambertian photometric flow fields.

  1. High contrast imaging with focal plane wavefront sensing for ground based telescopes

    NASA Astrophysics Data System (ADS)

    Guyon, Olivier; Gallet, Basile; Pluzhnik, Eugene A.; Takami, Hideki; Tamura, Motohide

    2006-06-01

    The techniques adopted in "classical" AO (sensing in the visible, imaging in the near-IR) limit the achievable raw PSF contrast to about 10 5 in the central arcsecond. On nearby stars, this level is far from the theoretical PSF contrast limit imposed by photon noise in the wavefront sensor. A comparative study between wavefront sensing strategies shows that a focal-plane based wavefront sensor (WFS), combining wavefront sensing and scientific imaging on the same detector, seems optimal for high contrast imaging. This approach combines high WFS sensitivity, immunity to aliasing, chromaticity, and non common path errors and optical design simplicity. We show that such a system can be efficiently used as a second stage "Extreme-AO" system after a low-order AO system. The images acquired by the science camera are then used to drive the high-order DM (which also introduces the phase diversity needed for focal plane wavefront sensing). This scheme offers much flexibility: with the proper DM updates, the focal plane images can be simultaneously used to solve for the entrance wavefront and the presence of companions (which are incoherent with the speckles) below the speckle noise level. Control and data reduction algorithms are presented, as well as possible optical designs incorporating a coronagraph. A laboratory demonstration of this technique is currently being done at Subaru Telescope with a 1024 actuators MEMs DM. This experiment serves as a prototype to plan and design a similar system for Subaru's upcoming HiCIAO instrument (near-IR coronagraphic imager for adaptive optics).

  2. Pars plana vitrectomy combined with focal endolaser photocoagulation for idiopathic macular telangiectasia.

    PubMed

    Terauchi, Gaku; Matsumoto, Celso Soiti; Shinoda, Kei; Matsumoto, Harue; Imamura, Yutaka; Watanabe, Emiko; Kondo, Takaaki; Mizota, Atsushi

    2014-01-01

    Background. To report the outcome of pars plana vitrectomy (PPV) combined with intraoperative endolaser focal photocoagulation (PC) on eyes with idiopathic macular telangiectasis (MacTel) type 1. Methods. This was a retrospective study of two female patients with MacTel type 1 who were resistant to focal photocoagulation, sub-Tenon triamcinolone injection, and/or antiangiogenic drugs. The best-corrected visual acuity (BCVA) was determined, and fluorescein angiography (FA) and spectral domain optical coherence tomography (SD-OCT) were performed before and after surgery for up to 19 months. Results. After surgery, the BCVA gradually improved from 20/100 to 20/20 at 19 months in Case 1 and from 20/50 to 20/13 at 13 months in Case 2. Fluorescein angiography (FA) showed leakage at the late phase, and OCT showed that the cystoid macular edema was resolved and the fovea was considerably thinner postoperatively. Conclusion. Patients with MacTel type 1 who are refractory to the other types of treatments can benefit from PPV combined with intraoperative endolaser focal PC with functional and morphological improvements. PMID:24876845

  3. Pars Plana Vitrectomy Combined with Focal Endolaser Photocoagulation for Idiopathic Macular Telangiectasia

    PubMed Central

    Terauchi, Gaku; Matsumoto, Celso Soiti; Shinoda, Kei; Matsumoto, Harue; Imamura, Yutaka; Watanabe, Emiko; Kondo, Takaaki; Mizota, Atsushi

    2014-01-01

    Background. To report the outcome of pars plana vitrectomy (PPV) combined with intraoperative endolaser focal photocoagulation (PC) on eyes with idiopathic macular telangiectasis (MacTel) type 1. Methods. This was a retrospective study of two female patients with MacTel type 1 who were resistant to focal photocoagulation, sub-Tenon triamcinolone injection, and/or antiangiogenic drugs. The best-corrected visual acuity (BCVA) was determined, and fluorescein angiography (FA) and spectral domain optical coherence tomography (SD-OCT) were performed before and after surgery for up to 19 months. Results. After surgery, the BCVA gradually improved from 20/100 to 20/20 at 19 months in Case 1 and from 20/50 to 20/13 at 13 months in Case 2. Fluorescein angiography (FA) showed leakage at the late phase, and OCT showed that the cystoid macular edema was resolved and the fovea was considerably thinner postoperatively. Conclusion. Patients with MacTel type 1 who are refractory to the other types of treatments can benefit from PPV combined with intraoperative endolaser focal PC with functional and morphological improvements. PMID:24876845

  4. The Course of Response to Focal/ Grid Photocoagulation for Diabetic Macular Edema

    PubMed Central

    2009-01-01

    Purpose To determine whether eyes with center involved diabetic macular edema (DME), treated with focal/grid photocoagulation, in which there is a reduction in central subfield thickness (CST) measured with optical coherence tomography (OCT) after 16 weeks, will continue to improve if retreatment is deferred. Methods Prospective, multi-center, observational, single group focal/grid photocoagulation study of 122 eyes with center involved DME (OCT CST ?250?). At the 16-week visit and continuing every 8 weeks, eyes were assessed for retreatment and additional laser was deferred if the visual acuity letter score improved ?5 letters or OCT CST decreased ?10% compared with the visit 16 weeks prior. Results Of the 115 eyes that completed the 16-week visit, 54 (47%) had a decrease in CST by ?10% compared with baseline. Of these, 26 (48%) had a CST ?250? at 16 weeks and were evaluable at 32 weeks. Eleven (42%, 95% confidence interval 23% to 63%) of the 26 eyes had a further decrease in CST ?10% from 16 to 32 weeks without further treatment. Conclusion Sixteen weeks following focal/grid laser for DME, in eyes with a definite reduction, but not resolution, of central edema, 23% to 63% will continue to improve without additional treatment. PMID:19898182

  5. Cell proliferation and synaptogenesis in the cerebellum after focal cerebral ischemia.

    PubMed

    Jung, Se Hee; Lee, Soon-Tae; Chu, Kon; Park, Jung-Eun; Lee, Shi-Uk; Han, Tai-Ryoon; Kim, Manho

    2009-08-11

    Cerebral ischemia induces cortical function reorganization and neocortical neurogenesis in the cerebral hemisphere. However, whether the cerebellum undergoes corresponding dynamic change after cerebral injury has not been determined. We investigated the characteristics of cell proliferation and synaptogenesis in the cerebellum after focal cerebral ischemia. After induction of focal cerebral ischemia in rats, bromodeoxyuridine (BrdU, 100 mg/kg, intraperitoneally, daily) was administered for 5 days. Brain sections were analyzed using immunohistochemistry at days 7, 14, and 28. BrdU+ cells and Iba-1+ cells were counted, and cerebellar synaptophysin immunoreactivity was quantitatively analyzed. Rats with cerebral ischemia showed increased numbers of BrdU+ cells in the cerebellum at day 28 compared to sham-operated rats. Neither neuronal markers nor GABAergic markers were co-labeled with BrdU+ cells, suggesting that none of the proliferating cells contributed to neurogenesis. Instead, the number of Iba-1+ cells in the cerebellum was increased, which suggests that microglia are activated in the cerebellum after cerebral ischemia. The optical density of synaptophysin in the cerebellum of rats with cerebral ischemia was significantly increased in the molecular and granular layers at days 7 and 14. Cerebellar synaptophysin expression was significantly correlated with cerebellar cell proliferation. This study shows that the cerebellum undergoes specific and dynamic changes at the cellular level after focal cerebral ischemia, including cell proliferation and synaptogenesis. PMID:19486898

  6. Semiconductor detectors and focal plane arrays for far-infrared imaging

    NASA Astrophysics Data System (ADS)

    Rogalski, A.

    2013-12-01

    The detection of far-infrared (far-IR) and sub-mm-wave radiation is resistant to the commonly employed techniques in the neighbouring microwave and IR frequency bands. In this wavelength detection range the use of solid state detectors has been hampered for the reasons of transit time of charge carriers being larger than the time of one oscillation period of radiation. Also the energy of radiation quanta is substantially smaller than the thermal energy at room temperature and even liquid nitrogen temperature. The realization of terahertz (THz) emitters and receivers is a challenge because the frequencies are too high for conventional electronics and the photon energies are too small for classical optics. Development of semiconductor focal plane arrays started in seventies last century and has revolutionized imaging systems in the next decades. This paper presents progress in far-IR and sub-mm-wave semiconductor detector technology of focal plane arrays during the past twenty years. Special attention is given on recent progress in the detector technologies for real-time uncooled THz focal plane arrays such as Schottky barrier arrays, field-effect transistor detectors, and microbolometers. Also cryogenically cooled silicon and germanium extrinsic photoconductor arrays, and semiconductor bolometer arrays are considered.

  7. Focal plane resolution and overlapped array time delay and integrate imaging

    NASA Astrophysics Data System (ADS)

    Grycewicz, Thomas J.; Cota, Stephen A.; Lomheim, Terrence S.; Kalman, Linda S.

    2010-06-01

    In this paper we model sub-pixel image registration for a generic earth-observing satellite system with a focal plane using two offset time delay and integrate (TDI) arrays in the focal plane to improve the achievable ground resolution over the resolution achievable with a single array. The modeling process starts with a high-resolution image as ground truth. The Parameterized Image Chain Analysis & Simulation Software (PICASSO) modeling tool is used to degrade the images to match the optical transfer function, sampling, and noise characteristics of the target system. The model outputs a pair of images with a separation close to the nominal half-pixel separation between the overlapped arrays. A registration estimation algorithm is used to measure the offset for image reconstruction. The two images are aligned and summed on a grid with twice the capture resolution. We compare the resolution in images between the inputs before overlap, the reconstructed image, and a simulation for the image which would have been captured on a focal plane with twice the resolution. We find the performance to always be better than the lower resolution baseline, and to approach the performance of the high-resolution array in the ideal case. We show that the overlapped array imager significantly outperforms both the conventional high- and low-resolution imagers in conditions with high image smear.

  8. The QWIP focal plane assembly for NASA's Landsat Data Continuity Mission

    NASA Astrophysics Data System (ADS)

    Jhabvala, M.; Reuter, D.; Choi, K.; Sundaram, M.; Jhabvala, C.; La, A.; Waczynski, A.; Bundas, J.

    2010-04-01

    The Thermal Infrared Sensor (TIRS) is a QWIP based instrument intended to supplement the Operational Land Imager (OLI) for the Landsat Data Continuity Mission (LDCM) [1]. The TIRS instrument is a dual channel far infrared imager with the two bands centered at 10.8?m and 12.0?m. The focal plane assembly (FPA) consists of three 640x512 GaAs Quantum Well Infrared Photodetector (QWIP) arrays precisely mounted to a silicon carrier substrate that is mounted on an invar baseplate. The two spectral bands are defined by bandpass filters mounted in close proximity to the detector surfaces. The focal plane operating temperature is 43K. The QWIP arrays are hybridized to Indigo ISC9803 readout integrated circuits (ROICs). Two varieties of QWIP detector arrays are being developed for this project, a corrugated surface structure QWIP and a grating surface structure QWIP. This paper will describe the TIRS system noise equivalent temperature difference sensitivity as it affects the QWIP focal plane performance requirements: spectral response, dark current, conversion efficiency, read noise, temperature stability, pixel uniformity, optical crosstalk and pixel yield. Additional mechanical constraints as well as qualification through Technology Readiness Level 6 (TRL 6) will also be discussed.

  9. InAs\\/GaSb superlattice focal plane arrays for high-resolution thermal imaging

    Microsoft Academic Search

    R. Rehm; M. Walther; J. Schmitz; J. Fleißner; F. Fuchs; J. Ziegler; W. Cabanski

    2006-01-01

    The first fully operational mid-IR (3–5 ?m) 256256 IR-FPA camera system based on a type-II InAs\\/GaSb short-period superlattice\\u000a showing an excellent noise equivalent temperature difference below 10 mK and a very uniform performance has been realized.\\u000a We report on the development and fabrication of the detecor chip, i.e., epitaxy, processing technology and electro-optical\\u000a characterization of fully integrated InAs\\/GaSb superlattice focal

  10. Analysis of focal adhesion turnover: A quantitative live cell imaging example

    PubMed Central

    Stehbens, Samantha

    2014-01-01

    Recent advances in optical and fluorescent protein technology have rapidly raised expectations in cell biology, allowing quantitative insights into dynamic intracellular processes like never before. However, quantitative live cell imaging comes with many challenges including how best to translate dynamic microscopy data into numerical outputs that can be used to make meaningful comparisons rather than relying on representative data sets. Here we use analysis of focal adhesion turnover dynamics as a straight-forward specific example on how to image, measure and analyze intracellular dynamics, but we believe this outlines a thought process and can provide guidance on how to understand dynamic microcopy data of other intracellular structures. PMID:24974036

  11. Depression in focal, segmental and generalized dystonia.

    PubMed

    Lewis, L; Butler, A; Jahanshahi, M

    2008-11-01

    Dystonia causes body disfigurement in the majority of those affected. Our aim was to test the hypothesis that low self-esteem resulting from the sense of disfigurement is an important component of self-reported depression in focal, segmental and generalized dystonia. Questionnaires to assess self-reported depression, self-esteem, body concept, disfigurement, disability and quality of life were completed by 329 community based dystonia patients. Moderate to severe depression was reported by 30 %. Self-reported depression had a strong somatic component, but patients also showed a specific concern with self-image. Extent of dystonia, body parts affected and marital status influenced self-reported depression in dystonia. Self esteem, body concept, disfigurement and quality of life emerged as factors which accounted for the variance of self-reported depression in dystonia. These results suggest that in dystonia, disfigurement, negative body concept, low self-esteem, and the impact of the disease on quality of life make important contributions to depression. However, longitudinal followup is required to firmly establish the direction of causality between depression and these psychosocial variables in dystonia. PMID:19156488

  12. Causes and pathogenesis of focal segmental glomerulosclerosis.

    PubMed

    Fogo, Agnes B

    2015-02-01

    Focal segmental glomerulosclerosis (FSGS) describes both a common lesion in progressive kidney disease, and a disease characterized by marked proteinuria and podocyte injury. The initial injuries vary widely. Monogenetic forms of FSGS are largely due to alterations in structural genes of the podocyte, many of which result in early onset of disease. Genetic risk alleles in apolipoprotein L1 are especially prevalent in African Americans, and are linked not only to adult-onset FSGS but also to progression of some other kidney diseases. The recurrence of FSGS in some transplant recipients whose end-stage renal disease was caused by FSGS points to circulating factors in disease pathogenesis, which remain incompletely understood. In addition, infection, drug use, and secondary maladaptive responses after loss of nephrons from any cause may also cause FSGS. Varying phenotypes of the sclerosis are also manifest, with varying prognosis. The so-called tip lesion has the best prognosis, whereas the collapsing type of FSGS has the worst prognosis. New insights into glomerular cell injury response and repair may pave the way for possible therapeutic strategies. PMID:25447132

  13. Focal adhesions as mechanosensors: A physical mechanism

    PubMed Central

    Shemesh, Tom; Geiger, Benjamin; Bershadsky, Alexander D.; Kozlov, Michael M.

    2005-01-01

    Focal adhesions (FA) are large, multiprotein complexes that provide a mechanical link between the cytoskeletal contractile machinery and the extracellular matrix. FA exhibit mechanosensitive properties; they self-assemble and elongate upon application of pulling forces and dissociate when these forces are decreased. We propose a thermodynamic model for the mechanosensitivity of FA, according to which a molecular aggregate, subjected to pulling forces, tends to grow in the direction of force application by incorporating additional molecules. We demonstrate that this principle is consistent with the phenomenology of FA dynamics by considering a one-dimensional protein aggregate subjected to pulling forces and anchored to the substrate. Depending on the force level, force distribution along the aggregate, and the character of its anchoring to the substrate, the aggregate is predicted to exhibit distinct modes of assembly that are largely consistent with the experimentally observed FA behavior. We define here specific conditions that can lead to the different regimes of FA assembly, including growth, steady state, and disassembly. PMID:16113084

  14. PATHOGENETIC MECHANISMS OF FOCAL CORTICAL DYSPLASIA

    PubMed Central

    Marin-Valencia, Isaac; Guerrini, Renzo; Gleeson, Joseph G.

    2014-01-01

    SUMMARY Objective Focal cortical dysplasias (FCDs) constitute a prevalent cause of intractable epilepsy in children, and one of the leading conditions requiring epilepsy surgery. Despite the recent advances on the cellular and molecular biology of these conditions, the pathogenetic mechanisms of FCDs remain largely unknown. The purpose if this work is to review the molecular underpinnings of FCDs and to highlight potential therapeutic targets. Methods A systematic review of the literature regarding the histological, molecular, and electrophysiological aspects of FCDs was conducted. Results Disruption of the mTOR signaling comprises a common pathway underlying the structural and electrical disturbances of some FCDs. Other mechanisms such as viral infections, prematurity, head trauma, and brain tumors are also posited. mTOR inhibitors (i.e., rapamycin) have shown positive results on seizure management in animal models and in a small cohort of patients with FCD. Significance Encouraging progresses have been achieved on the molecular and electrophysiological basis of constitutive cells in the dysplastic tissue. Despite the promising results of mTOR inhibitors, large-scale randomized trials are in need to evaluate their efficacy and side effects, along with additional mechanistic studies for the development of novel, molecular-based diagnostic and therapeutic approaches. PMID:24861491

  15. Focal cooling rapidly terminates experimental neocortical seizures.

    PubMed

    Yang, X F; Rothman, S M

    2001-06-01

    The efficacy of surgical resection for epilepsy is considerably lower for neocortical epilepsy than for temporal lobe epilepsy. We have explored focal cooling with a thermoelectric (Peltier) device as a potential therapy for neocortical epilepsy. After creating a cranial window in anesthetized rats, we induced seizures by injecting artificial cerebrospinal fluid containing 4-aminopyridine (4-AP), a potassium channel blocker. Within 30 minutes of 4-AP injection, animals developed recurrent seizures (duration 85.7 +/- 26.2 seconds; n = 10 rats) that persisted for 2 hours. When a small Peltier device cooled the exposed cortical surface to 20-25 degrees C at seizure onset, the seizure duration was reduced to 8.4 +/- 5.0 seconds (n = 10 rats; p < 0.001). When the Peltier device was placed close to the cortical surface, but not allowed to make physical contact, there was no effect on seizure duration (104.3 +/- 20.7 seconds; p > 0.05 compared to control). Interestingly, the duration of uncooled seizures was reduced after we allowed the cortex to rewarm from prior cooling. Histological examination of the cortex after cooling has shown no evidence of acute or delayed neuronal injury, and blood pressure and temperature remained stable. It may be possible to use Peltier devices for cortical mapping or, when seizure detection algorithms improve, for chronic seizure control. PMID:11409423

  16. Focal Atrial Tachycardia Surrounding the Anterior Septum

    PubMed Central

    Wang, Zulu; Ouyang, Jinge; Liang, Yanchun; Jin, Zhiqing; Yang, Guitang; Liang, Ming; Li, Shibei; Yu, Haibo

    2015-01-01

    Background— Focal atrial tachycardias (ATs) surrounding the anterior atrial septum (AAS) have been successfully ablated from the right atrial septum (RAS), the aortic cusps, and the aortic mitral junction. However, the strategy for mapping and ablation of AAS-ATs has not been well defined. Methods and Results— Of 227 consecutive patients with AT, 47 (20.7%; mean age, 56.3±11.6 years) with AAS-ATs were studied; among them, initial ablation was successful at RAS in only 5 of 14 patients and at noncoronary cusp (NCC) in 28 of 33 patients. In 45 of the 47 patients, the 46 of 48 AAS-ATs were eliminated at RAS in 8 patients, NCC in 35 patients (earliest activation time at NCC was later than that at RAS by 5–10 ms in 6 patients), and aortic mitral junction in 3 patients (all with negative P wave in lead aVL and positive P wave in the inferior leads), including 1 patient whose 2 ATs were eliminated separately from the NCC and the aortic mitral junction. Conclusions— Most of the ATs surrounding the AAS can be eliminated from within the NCC, which is usually the preferential ablation site. Ablation at the RAS and aortic mitral junction should be considered when supported by P-wave morphologies on surface ECG and results of activation mapping and ablation. PMID:25908691

  17. Multiwavelength infrared focal plane array detector

    NASA Technical Reports Server (NTRS)

    Forrest, Stephen R. (Inventor); Olsen, Gregory H. (Inventor); Kim, Dong-Su (Inventor); Lange, Michael J. (Inventor)

    1995-01-01

    A multiwavelength focal plane array infrared detector is included on a common substrate having formed on its top face a plurality of In.sub.x Ga.sub.1-x As (x.ltoreq.0.53) absorption layers, between each pair of which a plurality of InAs.sub.y P.sub.1-y (y<1) buffer layers are formed having substantially increasing lattice parameters, respectively, relative to said substrate, for preventing lattice mismatch dislocations from propagating through successive ones of the absorption layers of decreasing bandgap relative to said substrate, whereby a plurality of detectors for detecting different wavelengths of light for a given pixel are provided by removing material above given areas of successive ones of the absorption layers, which areas are doped to form a pn junction with the surrounding unexposed portions of associated absorption layers, respectively, with metal contacts being formed on a portion of each of the exposed areas, and on the bottom of the substrate for facilitating electrical connections thereto.

  18. Mid-IR quantum cascade laser mode coupling in hollow-core, fiber-optic waveguides with single-mode beam delivery

    NASA Astrophysics Data System (ADS)

    Patimisco, P.; Sampaolo, A.; Kriesel, J. M.; Scamarcio, G.; Spagnolo, V.

    2015-01-01

    We report a theoretical and experimental study of laser coupling in hollow-core, fiber-optic waveguides with small-bore diameters of d=200 ?m. For the experiments we utilized three mid-infrared quantum cascade lasers with different emission wavelength, which were coupled into the waveguides using lenses with focal lengths in the range 25-76 mm. Measurements of the output beam profiles and propagation losses were obtained as a function of the coupling conditions. With appropriate coupling parameters, single mode beam delivery can be obtained for all laser wavelengths, ranging from ? ~ 5.4 to 10.5 ?m.

  19. Rapid rotation of micron and submicron dielectric particles measured using optical tweezers

    E-print Network

    Leake, Mark C.

    (`optical tweezers') and back-focal-plane position detector to measure rapid rotation in aqueous solution]. In the latter technique, the emerging laser beam is collimated by a condenser lens and the back focal plane labelled with smaller beads were held at the centre of a microelectrode array by the optical tweezers

  20. Adaptive Optics Communications Performance Analysis

    NASA Technical Reports Server (NTRS)

    Srinivasan, M.; Vilnrotter, V.; Troy, M.; Wilson, K.

    2004-01-01

    The performance improvement obtained through the use of adaptive optics for deep-space communications in the presence of atmospheric turbulence is analyzed. Using simulated focal-plane signal-intensity distributions, uncoded pulse-position modulation (PPM) bit-error probabilities are calculated assuming the use of an adaptive focal-plane detector array as well as an adaptively sized single detector. It is demonstrated that current practical adaptive optics systems can yield performance gains over an uncompensated system ranging from approximately 1 dB to 6 dB depending upon the PPM order and background radiation level.

  1. Focal cemento-osseous dysplasia: review and a case report.

    PubMed

    Salem, Y M Y; Osman, Y I; Norval, E J G

    2010-10-01

    Focal cemento-osseous dysplasia is a benign fibro-osseous condition that can be seen in dentate and edentulous patients. It is an asymptomatic lesion and needs no treatment; however follow-up is essential due to the possibility that focal cemento-osseous dysplasia can progress to a condition called florid osseous dysplasia that involves multiple sites. A case report is presented here, along with a review of the differential diagnoses considered in order to reach a final diagnosis of focal cemento-osseous dysplasia. PMID:21180289

  2. Thermal analysis of the DES camera focal plate.

    SciTech Connect

    Guarino, V.; High Energy Physics

    2008-02-13

    A design specification for the DES Camera focal plate is to keep the deformation of the plate to less than 30 microns under operating conditions. Figure 1 shows the assembly of the focal plate, the support bipods and support ring, and the copper braid assemblies. Several studies were done to examine the deformation of the focal plate under different thermal and structural constraints. Simple hand calculations were also performed as a check of the finite element model and results. The main goal of this analysis was to determine the deformation of the plate and to understand what thermal and structural conditions are causing the deformation.

  3. Telomere Length Distribution and Southern Blot Analysis

    Microsoft Academic Search

    Konrad Oexle

    1998-01-01

    Southern blot analysis of terminal restriction fragments (TRFs) is the standard method for quantitative examination of telomere length distributions. Since TRFs contain a subtelomeric component, central parameters of the TRF distributionn(L) such as the arithmetic mean (M) or the median (Me) cannot be derived directly from Southern blot data, i.e. from the optical density distributionOD(L). Several estimates have been applied

  4. Optimization of the system consisting of the telescope and the focal-device unit in the Spectrum-UV Project

    Microsoft Academic Search

    A. L. Yaskovich; B. M. Shustov; A. V. Zverev

    2006-01-01

    This paper discusses the possibility of constructing high-quality images in a system consisting of a telescope with a nonflat focal surface and a flat detector. As an example, the approach that is used when creating the large extra-atmospheric UV observatory, Spectrum-UV, is described. It is shown that the optical system can be optimized in such a way that high image

  5. LWIR 128×128 GaAs\\/AlGaAs multiple quantum well hybrid focal plane array

    Microsoft Academic Search

    Lester J. Kozlowski; George M. Williams; Gerard J. Sullivan; Craig W. Farley; Robert J. Anderson; J. Chen; D. T. Cheung; W. E. Tennant; R. E. DeWames

    1991-01-01

    The authors describe the fabrication and performance of a new type of hybrid focal plane array (FPA). The hybrid consists of a 128×128 GaAs\\/AlGaAs superlattice multiple-quantum-well detector array with peak response at 7.7 ?m mated to a high-performance CMOS readout with direct injection input. The quantum-well infrared photodetector (QWIP) array was fabricated by molecular-beam epitaxy (MBE). Optical gratings were excluded

  6. 1024 × 1024 pixel mid-wavelength and long-wavelength infrared QWIP focal plane arrays for imaging applications

    Microsoft Academic Search

    S D Gunapala; S V Bandara; J K Liu; C J Hill; S B Rafol; J M Mumolo; J T Trinh; M Z Tidrow; P D LeVan

    2005-01-01

    Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024 × 1024 pixel quantum well infrared photodetector (QWIP) focal planes have been demonstrated with excellent imaging performance. The MWIR QWIP detector array has demonstrated a noise equivalent differential temperature (NE?T) of 17 mK at a 95 K operating temperature with f\\/2.5 optics at 300 K background and the LWIR detector array has

  7. Studying the characteristics of a VS-CTT-075-60 CCD camera during recording of focal spots

    Microsoft Academic Search

    D. S. Gavrilov; A. G. Kakshin; E. A. Loboda; I. A. Sorokin; A. A. Ugodenko

    2007-01-01

    A technique for monitoring the focusing quality of a diffraction-limited optical system with the use of a VS-CTT-075-60 CCD\\u000a camera with an uncooled CCD-based sensor is presented. The advantages of this technique over the widespread testing method\\u000a involving consecutive measurements of the radiation power transmitted through calibrated diaphragms of different diameters,\\u000a which are installed in the focal plane, are demonstrated.

  8. Thermoelectric infrared detectors with improved mechanical stability for the composite infrared spectrometer (CIRS) far-infrared focal plane

    Microsoft Academic Search

    Rainer Fettig; Brook Lakew; John C. Brasunas; Julie A. Crooke; Claef F. Hakun; Jon Orloff

    1998-01-01

    The Composite InfraRed Spectrometer (CIRS) instrument aboard the Cassini spacecraft en route to Saturn is a cryogenic spectrometer with far-infrared (FIR) and mid-infrared channels. The CIRS FIR focal plane, which covers the spectral range of 10 - 600 cm-1, consists of focusing optics and an output polarizer\\/analyzer that splits the output radiation according to polarization. The reflected and transmitted components

  9. Long life, high performance anti-reflection treatment for HgCdTe infrared focal plane arrays

    Microsoft Academic Search

    Bruce D. MacLeod; Douglas S. Hobbs

    2008-01-01

    The image contrast and clarity recorded by backside illuminated HgCdTe focal plane arrays (FPAs) is strongly dependent on minimizing signal loss and detector noise caused by scattered and reflected light from the FPA window and imaging optics. Thin film anti-reflection (AR) treatments based on stacks of thin-film materials have been exclusively used to minimize substrate reflections for this application. The

  10. Simulation of proton-induced transients on visible and infrared focal plane arrays in a space environment

    Microsoft Academic Search

    Tracy E. Dutton; Warren F. Woodward; Terrence S. Lomheim

    1997-01-01

    A simulation is describe which determines in detail the response of visible through infrared focal plane devices, used in space-based electro-optical imaging sensors, to proton irradiation from the natural space environment, as a function of the choice of orbit around the earth. The quantitative description of the natural environment (protons) is based on the NASA code AP-8 and\\/or the CRRES

  11. Physical insight toward electric field enhancement at nodular defects in optical coatings.

    PubMed

    Cheng, Xinbin; Tuniyazi, Abudusalamu; Wei, Zeyong; Zhang, Jinlong; Ding, Tao; Jiao, Hongfei; Ma, Bin; Li, Hongqiang; Li, Tongbao; Wang, Zhanshan

    2015-04-01

    Although the finite-difference time-domain (FDTD) technique has been prevailingly used to calculate the electric field intensity (EFI) enhancement at nodular defects in high-reflection (HR) coatings, the physical insight as to how the nodular features contribute to the intensified EFI is not explicitly revealed yet, which in turn limits the solutions that improve the laser-induced damage threshold (LIDT) of nodules by decreasing the EFI enhancement. Here, a simplified model is proposed to describe the intensified EFI in nodules: 1) the nodule works as a microlens and its focal length can be predicted using a simple formula, 2) the portion of incident light that penetrates through the HR coating can be estimated by knowing the angular dependent transmittance (ADT) of the nodule, 3) strong EFI enhancement is created when the focal point is within the nodule and simultaneously a certain portion of light penetrates to the focal position. In the light of the proposed model, a broadband HR coating was used to reduce the EFI enhancement at the seed by a factor about 10, which leads to a 20 times increment of the LIDT. This work therefore not only deepens the physical understanding of EFI enhancement at nodules but also provides a new way to increase the LIDT of multilayer reflective optics. PMID:25968699

  12. Validating Phasing and Geometry of Large Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Standley, Shaun P.; Gautier, Thomas N.; Caldwell, Douglas A.; Rabbette, Maura

    2011-01-01

    The Kepler Mission is designed to survey our region of the Milky Way galaxy to discover hundreds of Earth-sized and smaller planets in or near the habitable zone. The Kepler photometer is an array of 42 CCDs (charge-coupled devices) in the focal plane of a 95-cm Schmidt camera onboard the Kepler spacecraft. Each 50x25-mm CCD has 2,200 x 1,024 pixels. The CCDs accumulate photons and are read out every six seconds to prevent saturation. The data is integrated for 30 minutes, and then the pixel data is transferred to onboard storage. The data is subsequently encoded and transmitted to the ground. During End-to-End Information System (EEIS) testing of the Kepler Mission System (KMS), there was a need to verify that the pixels requested by the science team operationally were correctly collected, encoded, compressed, stored, and transmitted by the FS, and subsequently received, decoded, uncompressed, and displayed by the Ground Segment (GS) without the outputs of any CCD modules being flipped, mirrored, or otherwise corrupted during the extensive FS and GS processing. This would normally be done by projecting an image on the focal plane array (FPA), collecting the data in a flight-like way, and making a comparison between the original data and the data reconstructed by the science data system. Projecting a focused image onto the FPA through the telescope would normally involve using a collimator suspended over the telescope opening. There were several problems with this approach: the collimation equipment is elaborate and expensive; as conceived, it could only illuminate a limited section of the FPA (.25 percent) during a given test; the telescope cover would have to be deployed during testing to allow the image to be projected into the telescope; the equipment was bulky and difficult to situate in temperature-controlled environments; and given all the above, test setup, execution, and repeatability were significant concerns. Instead of using this complicated approach of projecting an optical image on the FPA, the Kepler project developed a method using known defect features in the CCDs to verify proper collection and reassembly of the pixels, thereby avoiding the costs and risks of the optical projection approach. The CCDs composing the Kepler FPA, as all CCDs, had minor defects. At ambient temperature, some pixels look far brighter than they should. These ghot h pixels have a higher rate of charge leakage than the others due to manufacturing variations. They are usually stable over time, and appear at temperatures above 5 oC. The hot pixels on the Kepler FPA were mapped before photometer assembly during module testing. Selected hot pixels were used as target gstars h for the purposes of EEIS testing. gDead h pixels are permanently off, producing a permanently black pixel. These can also be used if there is some illumination of the FPA. During EEIS testing, Dark Current Full Frame Images (FFIs) taken at room temperature were used to create the hot pixel maps for all 84 Kepler photometer CCD channels. Data from two separate nights were used to create two hot pixel maps per channel, which were cross-correlated to remove cosmic ray events which appear to be hot pixels. These hot pixel maps obtained during EEIS testing were compared to the maps made during module testing to verify that the end-to-end data flow was correct.

  13. Hollow fiber optic probe for in vivo Raman measurement

    NASA Astrophysics Data System (ADS)

    Katagiri, Takashi; Hattori, Yusuke; Komachi, Yuichi; Matsuura, Yuji; Tashiro, Hideo; Sato, Hidetoshi

    2006-10-01

    A hollow optical fiber Raman probe equipped with a ball lens is developed to study the stomach cancer. The probe generates little Raman scattering or fluorescence noise because the HOF confine light into the air core. In order to maximize the collection efficiency and the spatial resolution, material and size of the ball lens is optimized. The total diameter of the probe head is 0.64 mm. The probe is useful for measurement of layered sample by the contact mode because it has very short focal length and high depth resolution. In vivo experiments in a stomach of a living rat demonstrate the high viability of the probe for noninvasive diagnosis of the stomach cancer.

  14. Widespread EEG changes precede focal seizures.

    PubMed

    Perucca, Piero; Dubeau, François; Gotman, Jean

    2013-01-01

    The process by which the brain transitions into an epileptic seizure is unknown. In this study, we investigated whether the transition to seizure is associated with changes in brain dynamics detectable in the wideband EEG, and whether differences exist across underlying pathologies. Depth electrode ictal EEG recordings from 40 consecutive patients with pharmacoresistant lesional focal epilepsy were low-pass filtered at 500 Hz and sampled at 2,000 Hz. Predefined EEG sections were selected immediately before (immediate preictal), and 30 seconds before the earliest EEG sign suggestive of seizure activity (baseline). Spectral analysis, visual inspection and discrete wavelet transform were used to detect standard (delta, theta, alpha, beta and gamma) and high-frequency bands (ripples and fast ripples). At the group level, each EEG frequency band activity increased significantly from baseline to the immediate preictal section, mostly in a progressive manner and independently of any modification in the state of vigilance. Preictal increases in each frequency band activity were widespread, being observed in the seizure-onset zone and lesional tissue, as well as in remote regions. These changes occurred in all the investigated pathologies (mesial temporal atrophy/sclerosis, local/regional cortical atrophy, and malformations of cortical development), but were more pronounced in mesial temporal atrophy/sclerosis. Our findings indicate that a brain state change with distinctive features, in the form of unidirectional changes across the entire EEG bandwidth, occurs immediately prior to seizure onset. We postulate that these changes might reflect a facilitating state of the brain which enables a susceptible region to generate seizures. PMID:24260523

  15. Magnetoencephalography (MEG) predicts focal epileptogenicity in cavernomas

    PubMed Central

    Stefan, H; Scheler, G; Hummel, C; Walter, J; Romstock, J; Buchfelder, M; Blumcke, I

    2004-01-01

    Objective: The aim of this study was to identify the irritative epileptic zone in patients with cavernomas by means of magnetoencephalography (MEG). Method: Among 82 patients operated for epilepsy, whose presurgical evaluation had included MEG, histological assessment of the tissue removed had confirmed cavernomas in eight. These eight patients had epilepsy since 18.6 (SD 12.7) years on average. The monitoring lasted about 2.1 (SD 1.3) hours and a median 20.9 (SD 14.3) spikes per hour were recorded. Spontaneous brain activity was recorded by means of a 74 channel dual unit MEG system (Magnes II, 4-D Neuroimaging) with simultaneous EEG recording (31 scalp electrodes). Spike analysis was performed using different source (moving dipole, current density reconstruction) and head models (spherical shells, BEM). Co-registration of neurophysiological and imaging data (MRI) was based upon anatomical landmarks. Results: In 6/8 patients co-localisation from the cavernoma and epileptic zone was found. In two patients the focus was localised in the parieto-occipital lobe, in three patients in the frontal lobe and in three patients in the temporal lobe. In one case of temporal and one case of frontal lobe focus localisation there was no spatial relationship to the cavernoma. Conclusion: In cases of focal seizures due to a single cavernoma, MEG may precisely delineate the epileptogenic tissue bordering the lesion. In patients with multiple cavernomas or dual pathology, MSI may reveal the complexity of the case, and contribute to the decision about further invasive diagnostics and more sophisticated therapeutic measures. MEG is a promising method for prediction of the epileptic zone in cavernoma related epilepsies, and thus it can contribute to decision making about and planning of epilepsy surgery. PMID:15314122

  16. Spreading Depression in Focal Ischemia: A Computational Study

    E-print Network

    Ruppin, Eytan

    Spreading Depression in Focal Ischemia: A Computational Study February 27, 1997 Kenneth Revett cortical spreading depression (CSD) waves, i.e., by ischemic depolarizations. We describe here depression, computational models, stroke, ischemic penumbra and post-infarct debilitation. Running title

  17. Oral focal mucinosis: a rare case with literature review.

    PubMed

    Sowmya, G V; Manjunatha, Bhari Sharanesha; Nahar, Prashant; Aggarwal, Hersheal

    2015-01-01

    Oral focal mucinosis (OFM) is an unusual disease that affects diverse localised areas of the mouth, where the connective tissue undergoes focal degeneration. It was described for the first time by Tomich in 1974. It presents as an asymptomatic pedunculated or sessile growth, commonly on the gingiva, with most cases being in women. Its pathogenesis is linked to overproduction of hyaluronic acid by fibroblasts during collagen production, ensuing in focal myxoid degeneration. It has no characteristic features and diagnosis depends on histological scrutiny. We report a rare case of oral focal mucinosis affecting a 54-year-old man who presented with a sessile gingival growth mimicking a common tumour-like lesion. PMID:25759271

  18. A practical approach to management of focal hand dystonia

    PubMed Central

    Pandey, Sanjay

    2015-01-01

    Dystonia can be focal, segmental, multifocal, generalized, or hemidystonia. Focal dystonia is localized to a specific part of the body. Overall upper limb is more commonly involved in focal dystonia than lower limb and since it starts from hand, focal hand dystonia (FHD) is a more accepted terminology. Writer's cramp and musician dystonia are commonest types of FHD. Typically this dystonia is task specific, but in some patients this specificity may be lost over a period of time. Segmental or generalized dystonia may also start as FHD, so a detailed clinical assessment is required, which should be supplemented by relevant investigations. Treatment includes oral medications, injection botulinum toxin, neurosurgery including neurostimulation, and rehabilitation. Role of injection botulinum toxin has been extensively studied in writer's cramp patients and found to be effective; however, selection of muscles and techniques of injection are crucial in getting best results. PMID:26019409

  19. A practical approach to management of focal hand dystonia.

    PubMed

    Pandey, Sanjay

    2015-01-01

    Dystonia can be focal, segmental, multifocal, generalized, or hemidystonia. Focal dystonia is localized to a specific part of the body. Overall upper limb is more commonly involved in focal dystonia than lower limb and since it starts from hand, focal hand dystonia (FHD) is a more accepted terminology. Writer's cramp and musician dystonia are commonest types of FHD. Typically this dystonia is task specific, but in some patients this specificity may be lost over a period of time. Segmental or generalized dystonia may also start as FHD, so a detailed clinical assessment is required, which should be supplemented by relevant investigations. Treatment includes oral medications, injection botulinum toxin, neurosurgery including neurostimulation, and rehabilitation. Role of injection botulinum toxin has been extensively studied in writer's cramp patients and found to be effective; however, selection of muscles and techniques of injection are crucial in getting best results. PMID:26019409

  20. Real-time focal stack compositing for handheld mobile cameras

    NASA Astrophysics Data System (ADS)

    Solh, Mashhour

    2013-03-01

    Extending the depth of field using a single lens camera on a mobile device can be achieved by capturing a set of images each focused at a different depth or focal stack then combine these samples of the focal stack to form a single all-in-focus image or an image refocused at a desired depth of field. Focal stack compositing in real time for a handheld mobile camera has many challenges including capturing, processing power, handshaking, rolling shutter artifacts, occlusion, and lens zoom effect. In this paper, we describe a system for a real time focal stack compositing system for handheld mobile device with an alignment and compositing algorithms. We will also show all-in-focus images captured and processed by a cell phone camera running on Android OS.

  1. Quantitative multi-modal analysis of pediatric focal epilepsy

    E-print Network

    Eow, Andy Khai Siang

    2005-01-01

    For patients with medically refractive focal epilepsy, surgical intervention to remove the epileptic foci is often the last alternative for permanent cure. The success of such surgery is highly dependent on the doctor's ...

  2. Dynamics of similariton pulses in length-inhomogeneous active fibres

    SciTech Connect

    Zolotovskii, Igor' O; Sementsov, Dmitrii I; Yavtushenko, M S [Ulyanovsk State University, Ulyanovsk (Russian Federation); Senatorov, A K; Sysolyatin, A A [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

    2010-05-26

    The possibility of producing self-similar frequency-modulated (FM) optical wave packets in length-inhomogeneous active fibres is studied for optical pulses with the initial Gaussian, hyperbolic-secant or parabolic shape. The conditions for converting these pulses into stable parabolic-type pulses with a constant frequency-modulation rate are considered. It is shown that the use of FM pulses of parabolic shape in active and length-inhomogeneous fibres can ensure the creation of an all-fibre generator-amplifier-compressor system with peak powers up to 1 MW and higher in the generated pulses. (nonlinear optical phenomena)

  3. Length of the Day

    NSDL National Science Digital Library

    2012-08-03

    In this activity, students measure the length of the day using the rotation of the Earth, and discover that the Sun is not exactly in the same place at the same clock time every day, understand that the changes are due to motions of the Earth, and lead to differences in solar, star, and sidereal time. This resource is from PUMAS - Practical Uses of Math and Science - a collection of brief examples created by scientists and engineers showing how math and science topics taught in K-12 classes have real world applications.

  4. Extending hyperspectral capabilities with dualband infrared focal plane arrays

    Microsoft Academic Search

    Paul D. LeVan; John P. Hartke; Eustace L. Dereniak; Brian P. Beecken

    2007-01-01

    Dualband infrared focal plane arrays (FPA) were developed originally for multi-spectral imaging applications, where their advantages in compactness and band-to-band pixel registration, relative to conventional multispectral imagers, were recognized. As dualband FPA architecture is matured for quantum well and mercury cadmium telluride focal plane arrays, and becomes within the grasp of strained layer superlattice technology, applications in addition to multi-waveband

  5. Extending hyperspectral capabilities with dualband Infrared Focal Plane Arrays

    Microsoft Academic Search

    Paul D. LeVan; John P. Hartke; Eustace L. Dereniak; Brian P. Beecken

    2007-01-01

    Dualband infrared focal plane arrays (FPA) were developed originally for multi-spectral imaging applications, where their advantages in compactness and band-to-band pixel registration, relative to conventional multispectral imagers, were recognized. As dualband FPA architecture is matured for quantum well and mercury cadmium telluride focal plane arrays, and becomes within the grasp of strained layer superlattice technology, applications in addition to multi-waveband

  6. A New Method for Determining First-Motion Focal Mechanisms

    Microsoft Academic Search

    Jeanne L. Hardebeck; Peter M. Shearer

    2002-01-01

    We introduce a new method for determining earthquake focal mecha- nisms from P-wave first-motion polarities. Our technique differs from previous meth- ods in that it accounts for possible errors in the assumed earthquake location and seismic-velocity model, as well as in the polarity observations. The set of acceptable focal mechanisms, allowing for the expected errors in polarities and takeoff angles,

  7. Two-dimensional tracking of ncd motility by back focal plane interferometry.

    PubMed Central

    Allersma, M W; Gittes, F; deCastro, M J; Stewart, R J; Schmidt, C F

    1998-01-01

    A technique for detecting the displacement of micron-sized optically trapped probes using far-field interference is introduced, theoretically explained, and used to study the motility of the ncd motor protein. Bead motions in the focal plane relative to the optical trap were detected by measuring laser intensity shifts in the back-focal plane of the microscope condenser by projection on a quadrant diode. This detection method is two-dimensional, largely independent of the position of the trap in the field of view and has approximately 10-micros time resolution. The high resolution makes it possible to apply spectral analysis to measure dynamic parameters such as local viscosity and attachment compliance. A simple quantitative theory for back-focal-plane detection was derived that shows that the laser intensity shifts are caused primarily by a far-field interference effect. The theory predicts the detector response to bead displacement, without adjustable parameters, with good accuracy. To demonstrate the potential of the method, the ATP-dependent motility of ncd, a kinesin-related motor protein, was observed with an in vitro bead assay. A fusion protein consisting of truncated ncd (amino acids 195-685) fused with glutathione-S-transferase was adsorbed to silica beads, and the axial and lateral motions of the beads along the microtubule surface were observed with high spatial and temporal resolution. The average axial velocity of the ncd-coated beads was 230 +/- 30 nm/s (average +/- SD). Spectral analysis of bead motion showed the increase in viscous drag near the surface; we also found that any elastic constraints of the moving motors are much smaller than the constraints due to binding in the presence of the nonhydrolyzable nucleotide adenylylimidodiphosphate. PMID:9533719

  8. Optical system design of multi-spectral and large format color CCD aerial photogrammetric camera

    NASA Astrophysics Data System (ADS)

    Qian, Yixian; Sun, Tianxiang; Gao, Xiaodong; Liang, Wei

    2007-12-01

    Multi-spectrum and high spatial resolution is the vital problem for optical design of aerial photogrammetric camera all the time. It is difficult to obtain an outstanding optical system with high modulation transfer function (MTF) as a result of wide band. At the same time, for acquiring high qualified image, chromatic distortion in optical system must be expected to be controlled below 0.5 pixels; it is a trouble thing because of wide field and multi-spectrum. In this paper, MTF and band of the system are analyzed. A Russar type photogrammetric objective is chosen as the basic optical structure. A novel optical system is presented to solve the problem. The new optical photogrammetric system, which consists of panchromatic optical system and chromatic optical system, is designed. The panchromatic optical system, which can obtain panchromatic image, makes up of a 9k×9k large format CCD and high-accuracy photographic objective len, its focal length is 69.83mm, field angle is 60°×60°, the size of CCD pixels is 8.75um×8.75um, spectral scope is from 0.43um to 0.74um, modulation transfer function is all above 0.4 in whole field when spatial frequency is at 60lp/mm, distortion is less than 0.007%. In a chromatic optical system, three 2k×2k array CCDs combine individually three same photographic objectives, the high resolution chromatic image is acquired by the synthesis of red, green, blue image data information delivered by three CCD sensors. For the chromatic system, their focal length is 24.83mm and they have the same spectral range of 0.39um to 0.74um. A difference is that they are coated in different film on their protect glass. The pixel number is 2048 × 2048; its MTF exceeds 0.4 in full field when spatial frequency is 30lp/mm. The advantages of digital aerial photogrammetric camera comparison with traditional film camera are described. It is considered that the two development trends on digital aerial photogrammetric camera are high-spectral resolution and high-spatial resolution. Merits of the aerial photogrammetric camera are multi-spectral, high resolution, low distortion and light-weight and wide field. It can apply in aerial photography and remote sense in place of traditional film camera. After put on trial and analyzing from the design results, the system can meet large scale aerial survey.

  9. Path length enhancement in disordered media for increased absorption

    E-print Network

    Mupparapu, Rajeshkumar; Svensson, Tomas; Burresi, Matteo; Wiersma, Diederik S

    2015-01-01

    We theoretically and numerically investigate the capability of disordered media to enhance the optical path length in dielectric slabs and augment their light absorption efficiency due to scattering. We first perform a series of Monte Carlo simulations of random walks to determine the path length distribution in weakly to strongly (single to multiple) scattering, non-absorbing dielectric slabs under normally incident light and derive analytical expressions for the path length enhancement in these two limits. Quite interestingly, while multiple scattering is expected to produce long optical paths, we find that media containing a vanishingly small amount of scatterers can still provide high path length enhancements due to the very long trajectories sustained by total internal reflection at the slab interfaces. The path length distributions are then used to calculate the light absorption efficiency of media with varying absorption coefficients. We find that maximum absorption enhancement is obtained at an optima...

  10. Thermomechanical architecture of the VIS focal plane for Euclid

    NASA Astrophysics Data System (ADS)

    Martignac, Jérôme; Carty, Michaël.; Tourette, Thierry; Bachet, Damien; Berthé, Michel; Augueres, Jean-Louis; Amiaux, Jérôme; Fontignie, Jean; Horeau, Benoît; Renaud, Diana; Pottinger, Sabrina; Denniston, James; Winter, Berend; Guttridge, Phillip; Cole, Richard; Cropper, Mark; Niemi, Sami; Coker, John; Hunt, Thomas

    2014-08-01

    One of the main challenges for current and near future space experiments is the increase of focal plane complexity in terms of amount of pixels. In the frame work of the ESA Euclid mission to be launched in 2020, the Euclid Consortium is developing an extremely large and stable focal plane for the VIS instrument. CEA has developed the thermomechanical architecture of that Focal Plane taking into account all the very stringent performance and mission related requirements. The VIS Focal Plane Assembly integrates 36 CCDs (operated at 150K) connected to their front end electronics (operated at 280K) as to obtain one of the largest focal plane (˜0.6 billion pixels) ever built for space application after the GAIA one. The CCDs are CCD273 type specially designed and provided by the e2v company under ESA contract, front end electronics is studied and provided by MSSL. In this paper we first recall the specific requirements that have driven the overall architecture of the VIS-FPA and especially the solutions proposed to cope with the scientific needs of an extremely stable focal plane, both mechanically and thermally. The mechanical structure based on SiC material used for the cold sub assembly supporting the CCDs is detailed. We describe also the modular architecture concept that we have selected taking into account AIT-AIV and programmatic constraints.

  11. Length of stain dosimeter

    NASA Technical Reports Server (NTRS)

    Lueck, Dale E. (inventor)

    1994-01-01

    Payload customers for the Space Shuttle have recently expressed concerns about the possibility of their payloads at an adjacent pad being contaminated by plume effluents from a shuttle at an active pad as they await launch on an inactive pad. As part of a study to satisfy such concerns a ring of inexpensive dosimeters was deployed around the active pad at the inter-pad distance. However, following a launch, dosimeters cannot be read for several hours after the exposure. As a consequence factors such as different substrates, solvent systems, and possible volatilization of HCl from the badges were studied. This observation led to the length of stain (LOS) dosimeters of this invention. Commercial passive LOS dosimeters are sensitive only to the extent of being capable of sensing 2 ppm to 20 ppm if the exposure is 8 hours. To map and quantitate the HCl generated by Shuttle launches, and in the atmosphere within a radius of 1.5 miles from the active pad, a sensitivity of 2 ppm HCl in the atmospheric gases on an exposure of 5 minutes is required. A passive length of stain dosimeter has been developed having a sensitivity rendering it capable of detecting a gas in a concentration as low as 2 ppm on an exposure of five minutes.

  12. Advanced optical tweezers for the study of cellular and molecular biomechanics

    Microsoft Academic Search

    Gary J. Brouhard; Henry T. Schek; Alan J. Hunt

    2003-01-01

    Optical tweezers are an important tool for studying cellular and molecular biomechanics. We present a robust optical tweezers device with advanced features including: multiple optical traps, acousto-optic trap steering, and back focal plane interferometry position detection. We integrate these features into an upright microscope, with no compromise to its capabilities (differential interference contrast microscopy (DIC), fluorescence microscopy, etc.). Acousto-optic deflectors

  13. X-Ray Diffractive Optics

    NASA Technical Reports Server (NTRS)

    Dennis, Brian; Li, Mary; Skinner, Gerald

    2013-01-01

    X-ray optics were fabricated with the capability of imaging solar x-ray sources with better than 0.1 arcsecond angular resolution, over an order of magnitude finer than is currently possible. Such images would provide a new window into the little-understood energy release and particle acceleration regions in solar flares. They constitute one of the most promising ways to probe these regions in the solar atmosphere with the sensitivity and angular resolution needed to better understand the physical processes involved. A circular slit structure with widths as fine as 0.85 micron etched in a silicon wafer 8 microns thick forms a phase zone plate version of a Fresnel lens capable of focusing approx. =.6 keV x-rays. The focal length of the 3-cm diameter lenses is 100 microns, and the angular resolution capability is better than 0.1 arcsecond. Such phase zone plates were fabricated in Goddard fs Detector Development Lab. (DDL) and tested at the Goddard 600-microns x-ray test facility. The test data verified that the desired angular resolution and throughput efficiency were achieved.

  14. Performance of 4x5120 Element Visible and 2x2560 Element Shortwave Infrared Multispectral Focal Planes

    NASA Astrophysics Data System (ADS)

    Tower, J. R.; Cope, A. D.; Pellion, L. E.; McCarthy, B. M.; Strong, R. T.; Kinnard, K. F.; Moldovan, A. G.; Levine, P. A.; Elabd, H.; Hoffman, D. M.

    1985-12-01

    Performance measurements of two Multispectral Linear Array focal planes are presented. Both pushbroom sensors have been developed for application in remote sensing instruments. A buttable, four-spectral-band, linear-format charge coupled device (CCD) and a but-table, two-spectral-band, linear-format, shortwave infrared charge coupled device (IRCCD) have been developed under NASA funding. These silicon integrated circuits may be butted end to end to provide very-high-resolution multispectral focal planes. The visible CCD is organized as four sensor lines of 1024 pixels each. Each line views the scene in a different spectral window defined by integral optical bandpass filters. A prototype focal plane with five devices, providing 4x5120-pixel resolution has been demonstrated. The high quantum efficiency of the backside-illuminated CCD technology provides excellent signal-to-noise performance and unusually high MTF across the entire visible and near-IR spectrum. The shortwave infrared (SWIR) sensor is organized as two line sensors of 512 detectors each. The SWIR (1-2.5 ?m) spectral windows may be defined by bandpass filters placed in close proximity to the devices. The dual-band sensor consists of Schottky barrier detectors read out by CCD multiplexers. This monolithic sensor operates at 125°K with radiometric performance. A prototype five-device focal plane providing 2x2560 detectors has been demonstrated. The devices provide very high uniformity, and excellent MTF across the SWIR band.

  15. Design and performance of a sub-nanoradian resolution autocollimating optical lever

    SciTech Connect

    Cowsik, R.; Srinivasan, R.; Kasturirengan, S.; Kumar, A. Senthil; Wagoner, K. [McDonnell Center for the Space Sciences, and Department of Physics, Washington University, St. Louis, Missouri 63130 (United States)

    2007-03-15

    Precision goniometry using optics has the advantage that it does not impose much stress on the object of investigation and, as such, is adopted extensively in gravitational wave detection, in torsion balances investigating fundamental forces, in specialized studies of biological samples, and it has potential applications in condensed matter physics. In this article we present the considerations that go into designing optical levers and discuss the performance of the instrument we have constructed. We motivate the design by considering an idealized setup and the limitations to the angular resolution induced by statistical fluctuations of the photon count rate and diffraction at the apertures. The effects of digitization of the count rate and of the spatial location of the photons on the image plane motivating the actual design are discussed next. Based on these considerations, we have developed an autocollimating optical lever which has a very high resolution and dynamic range. An array of 110 slits, of 90 {mu}m width and a pitch of 182 {mu}m, is located in the focal plane of a field lens, of focal length 1000 mm, and is illuminated by a CCFL tube. This array is imaged back onto the focal plane after retroreflection from a mirror placed just beyond the lens. The image is recorded on a linear charge-coupled device array at the rate of 1000 images/s and is processed through a special algorithm to obtain the centroid. The instrument has a centroid stability of {approx}3x10{sup -10} rad Hz{sup -1/2} and a dynamic range of {approx}10{sup 7}.

  16. Infrared focal plane design for the Comet Rendezvous/Asteroid Flyby and Cassini Visible and Infrared Mapping Spectrometers

    NASA Technical Reports Server (NTRS)

    Staller, Craig; Niblack, Curtiss; Evans, Thomas; Blessinger, Michael; Westrick, Anthony

    1991-01-01

    A focal plane assembly combining hybrid electronic components with passive optical components within a single hermetically sealed package has been designed by Cincinnati Electronics to meet the performance requirements imposed by the Comet Rendezvous/Asteroid Flyby (CRAF) and Cassini Visible and Infrared Mapping Spectrometers (VIMSs). A single line array of 256 InSb photodiodes, accessed by two 1 x 128 multiplexers, provides continuous spectral coverage from 0.85 to 5.1 microns. Intrinsic field-of-view apertures and a unique order sorting filter require critical optical alignment within the hybrid. FPA performance requirements, design approach, and critical issues are discussed.

  17. Effects of focal volume and spatial inhomogeneity on uncertainty in single-aerosol laser-induced breakdown spectroscopy measurements

    SciTech Connect

    Lithgow, G.A.; Buckley, S.G. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, California 92093-0411 (United States)

    2005-07-04

    Particle location with respect to the plasma volume and the focal volume of the collection optics is identified as an important source of uncertainty in single-aerosol laser-induced breakdown spectroscopy (LIBS) measurements. Two sets of optics were used to image different regions of a LIBS plasma and simultaneously collect spectra from single particles. Strong variation and lack of correlation between the two measurement channels suggest that emission from a single particle is localized within the plasma. Measurement precision and detection efficiency were improved by imaging a larger plasma region, thus integrating the spatially distributed signal.

  18. Compact Focal Plane Assembly for Planetary Science

    NASA Technical Reports Server (NTRS)

    Brown, Ari; Aslam, Shahid; Huang, Wei-Chung; Steptoe-Jackson, Rosalind

    2013-01-01

    A compact radiometric focal plane assembly (FPA) has been designed in which the filters are individually co-registered over compact thermopile pixels. This allows for construction of an ultralightweight and compact radiometric instrument. The FPA also incorporates micromachined baffles in order to mitigate crosstalk and low-pass filter windows in order to eliminate high-frequency radiation. Compact metal mesh bandpass filters were fabricated for the far infrared (FIR) spectral range (17 to 100 microns), a game-changing technology for future planetary FIR instruments. This fabrication approach allows the dimensions of individual metal mesh filters to be tailored with better than 10- micron precision. In contrast, conventional compact filters employed in recent missions and in near-term instruments consist of large filter sheets manually cut into much smaller pieces, which is a much less precise and much more labor-intensive, expensive, and difficult process. Filter performance was validated by integrating them with thermopile arrays. Demonstration of the FPA will require the integration of two technologies. The first technology is compact, lightweight, robust against cryogenic thermal cycling, and radiation-hard micromachined bandpass filters. They consist of a copper mesh supported on a deep reactive ion-etched silicon frame. This design architecture is advantageous when constructing a lightweight and compact instrument because (1) the frame acts like a jig and facilitates filter integration with the FPA, (2) the frame can be designed so as to maximize the FPA field of view, (3) the frame can be simultaneously used as a baffle for mitigating crosstalk, and (4) micron-scale alignment features can be patterned so as to permit high-precision filter stacking and, consequently, increase the filter bandwidth and sharpen the out-of-band rolloff. The second technology consists of leveraging, from another project, compact and lightweight Bi0.87Sb0.13/Sb arrayed thermopiles. These detectors consist of 30-layer thermopiles deposited in series upon a silicon nitride membrane. At 300 K, the thermopile arrays are highly linear over many orders of magnitude of incident IR power, and have a reported specific detectivity that exceeds the requirements imposed on future mission concepts. The bandpass filter array board is integrated with a thermopile array board by mounting both boards on a machined aluminum jig.

  19. Actopaxin, a new focal adhesion protein that binds paxillin LD motifs and actin and regulates cell adhesion.

    PubMed

    Nikolopoulos, S N; Turner, C E

    2000-12-25

    Paxillin is a focal adhesion adapter protein involved in the integration of growth factor- and adhesion-mediated signal transduction pathways. Paxillin LD motifs have been demonstrated to bind to several proteins associated with remodeling of the actin cytoskeleton including the focal adhesion kinase, vinculin, and a complex of proteins comprising p95PKL, PIX, and PAK (Turner, C.E., M. C. Brown, J.A. Perrotta, M.C. Riedy, S.N. Nikolopoulos, A.R. McDonald, S. Bagrodia, S. Thomas, and P.S. Leventhal. 1999. J. Cell Biol. 145:851-863). In this study, we report the cloning and initial characterization of a new paxillin LD motif-binding protein, actopaxin. Analysis of the deduced amino acid sequence of actopaxin reveals a 42-kD protein with two calponin homology domains and a paxillin-binding subdomain (PBS). Western blotting identifies actopaxin as a widely expressed protein. Actopaxin binds directly to both F-actin and paxillin LD1 and LD4 motifs. It exhibits robust focal adhesion localization in several cultured cell types but is not found along the length of the associated actin-rich stress fibers. Similar to paxillin, it is absent from actin-rich cell-cell adherens junctions. Also, actopaxin colocalizes with paxillin to rudimentary focal complexes at the leading edge of migrating cells. An actopaxin PBS mutant incapable of binding paxillin in vitro cannot target to focal adhesions when expressed in fibroblasts. In addition, ectopic expression of the PBS mutant and/or the COOH terminus of actopaxin in HeLa cells resulted in substantial reduction in adhesion to collagen. Together, these results suggest an important role for actopaxin in integrin-dependent remodeling of the actin cytoskeleton during cell motility and cell adhesion. PMID:11134073

  20. Actopaxin, a New Focal Adhesion Protein That Binds Paxillin Ld Motifs and Actin and Regulates Cell Adhesion

    PubMed Central

    Nikolopoulos, Sotiris N.; Turner, Christopher E.

    2000-01-01

    Paxillin is a focal adhesion adapter protein involved in the integration of growth factor– and adhesion-mediated signal transduction pathways. Paxillin LD motifs have been demonstrated to bind to several proteins associated with remodeling of the actin cytoskeleton including the focal adhesion kinase, vinculin, and a complex of proteins comprising p95PKL, PIX, and PAK (Turner, C.E., M.C. Brown, J.A. Perrotta, M.C. Riedy, S.N. Nikolopoulos, A.R. McDonald, S. Bagrodia, S. Thomas, and P.S. Leventhal. 1999. J. Cell Biol. 145:851–863). In this study, we report the cloning and initial characterization of a new paxillin LD motif–binding protein, actopaxin. Analysis of the deduced amino acid sequence of actopaxin reveals a 42-kD protein with two calponin homology domains and a paxillin-binding subdomain (PBS). Western blotting identifies actopaxin as a widely expressed protein. Actopaxin binds directly to both F-actin and paxillin LD1 and LD4 motifs. It exhibits robust focal adhesion localization in several cultured cell types but is not found along the length of the associated actin-rich stress fibers. Similar to paxillin, it is absent from actin-rich cell–cell adherens junctions. Also, actopaxin colocalizes with paxillin to rudimentary focal complexes at the leading edge of migrating cells. An actopaxin PBS mutant incapable of binding paxillin in vitro cannot target to focal adhesions when expressed in fibroblasts. In addition, ectopic expression of the PBS mutant and/or the COOH terminus of actopaxin in HeLa cells resulted in substantial reduction in adhesion to collagen. Together, these results suggest an important role for actopaxin in integrin-dependent remodeling of the actin cytoskeleton during cell motility and cell adhesion. PMID:11134073

  1. Focal Stack Photography: High-Performance Photography with a Conventional Camera

    E-print Network

    Toronto, University of

    , 21, 6]. Focal stacks are also a rich source of 3D shape information and have been used extensivelyFocal Stack Photography: High-Performance Photography with a Conventional Camera Kiriakos N" and "exposure time" to the case of focal stacks, we show that focal stack photography has two performance

  2. Odd Length Contraction

    NASA Astrophysics Data System (ADS)

    Smarandache, Florentin

    2013-09-01

    Let's denote by VE the speed of the Earth and byVR the speed of the rocket. Both travel in the same direction on parallel trajectories. We consider the Earth as a moving (at a constant speed VE -VR) spacecraft of almost spherical form, whose radius is r and thus the diameter 2r, and the rocket as standing still. The non-proper length of Earth's diameter, as measured by the astronaut is: L = 2 r?{ 1 -|/VE -VR|2 c2 } < 2 r . Therefore Earth's diameter shrinks in the direction of motion, thus Earth becomes an ellipsoid - which is untrue. Planet Earth may increase or decrease its diameter (volume), but this would be for other natural reasons, not because of a...flying rocket! Also, let's assume that the astronaut is laying down in the direction of motion. Therefore, he would also shrink, or he would die!

  3. Blaschko Linear Enamel Defects – A Marker for Focal Dermal Hypoplasia: Case Report of Focal Dermal Hypoplasia

    PubMed Central

    Gysin, Stefan; Itin, Peter

    2015-01-01

    Focal dermal hypoplasia (FDH) is a rare genetic skin disorder. The inheritance of FDH or Goltz-Gorlin syndrome is X-linked dominant and the disease is associated with a PORCN gene mutation. This gene plays a key role in the Wnt pathway, which has an impact on embryonic development. Every tissue derived from meso- and ectoderm can be affected. Patients suffer from cutaneous, ocular, osseous, oral and dental defects. The skin and dental alterations manifest along the Blaschko lines. We present a woman (born in 1962) suffering from FDH with congenital skin changes and Blaschko linear enamel defects. Typical symptoms (e.g. fat herniations, scoliosis, syndactyly, microphthalmia, caries and alopecia) plus vertical grooving of all teeth gave a first indication. Molecular genetic testing confirmed the definitive diagnosis of FDH. We hypothesize that, in the context of typical skin changes, visible Blaschko lines on the teeth in the form of vertical grooves are almost pathognomonic for FDH. PMID:26078738

  4. Optical processing for 3D digital imaging

    Microsoft Academic Search

    D. J. Brady

    2000-01-01

    Conventional optical imaging systems perform both information sensing and image formation functions. The optical system is generally designed to implement processing for image formation with a goal of optimizing analog image quality measures. Digital image involves a fundamental paradigm shift in which the “image” is no longer synonymous with the focal plane field distribution. A digital system may be designed

  5. Optically sectioned imaging by oblique plane microscopy

    Microsoft Academic Search

    Sunil Kumar; Ziduo Lin; Alex R. Lyon; Ken T. MacLeod; Chris Dunsby

    2011-01-01

    Oblique Plane Microscopy (OPM) is a light sheet microscopy technique that combines oblique illumination with correction optics that tilt the focal plane of the collection system. OPM can be used to image conventionally mounted specimens on coverslips or tissue culture dishes and has low out-of-plane photobleaching and phototoxicity. No moving parts are required to achieve an optically sectioned image and

  6. Differences in lens optical plasticity in two gadoid fishes meeting in the Arctic.

    PubMed

    Jönsson, Mikael; Varpe, Øystein; Koz?owski, Tomasz; Berge, Jørgen; Kröger, Ronald H H

    2014-11-01

    Arctic and boreal/temperate species are likely to be evolutionary adapted to different light regimes. Currently, the boreal/temperate Atlantic cod (Gadus morhua) is coexisting with the native polar cod (Boreogadus saida) in the Arctic waters around Svalbard, Norway. Here, we studied light/dark adaptative optical plasticity of their eye lenses by exposing fish to bright light during the polar night. Schlieren photography, high-definition laser scanning and ray tracing were used to determine the optical properties of excised crystalline lenses. Both species have multifocal lenses, an optical adaptation for improved color vision. In polar cod, the optical properties of the lens were independent of light exposure. In the more southern Atlantic cod, the optical properties of the lens changed within hours upon exposure to light, even after months of darkness. Such fast optical adjustment has previously only been shown in a tropical cichlid. During the polar night the Atlantic cod lens seems to be unregulated and dysfunctional since it had an unsuitable focal length and severe spherical aberration. We present a system, to our knowledge unique, for studying visual plasticity on different timescales in relation to evolutionary history and present the first study on the polar cod visual system. PMID:25240636

  7. Error analysis and design of the optical system in airborne remote sensing measurement

    NASA Astrophysics Data System (ADS)

    Lv, Chao; Sun, Anxin; Che, Ying

    2015-02-01

    In the system of airborne remote sensing measurement, the optical system should meet the requirements of long focal length, large aperture, light weight and wide waveband due to the particular characteristics of usage environment and observation objects. To meet the special requirements of the optical system structure, an off-axis four-mirror reflective optical system is designed based on an off-axis three-mirror reflective optical system from modern optical design theory. The structure and principle of the off-axis four-mirror reflective system are described and the MTF curve is given in this paper. At the same time, according to the working environmental condition of the system, the temperature adaptability of the system is analyzed and the analysis results are given. Based on the results, the system error is analyzed and discussed in detail applying the precision theory. The system error for each optical component is analyzed and allocated. The qualitative analysis for the influence factors of system error is also given.

  8. Inexpensive, high-quality optical relay for use in confocal scanning beam imaging

    PubMed

    Ribes; Damaskinos; Dixon

    2000-09-01

    An inexpensive, high optical-quality relay lens made up of two eyepieces arranged in an afocal assembly for use in confocal scanning laser imaging is described. In the past we have used relays, within our confocal microscopes, made up of achromats with long focal lengths (> or = 10 cm), which take up large optical tracks and suffer from significant amounts of astigmatism and curvature of field. We quantify aberrations associated with achromat and eyepiece relays using CODE V optical design and analysis software. The eyepiece relay is found to be more compact, better corrected, and not significantly more expensive than its achromat counterpart. In addition to being used to interconnect two scanning mirrors optically as well as scanning mirrors with microscope objectives, it can form part of the optics in a confocal scanning laser MACROscope-Microscope system (Biomedical Photometrics, Inc., Waterloo, Ontario, Canada). Due to design constraints, the MACROscope-Microscope system cannot incorporate a conventional wide-field microscope into its structure such as is done in most commercial confocal microscopes. The eyepiece relay is used as a stand-alone, compact optical link between the scanning mirrors and the microscope objective. This consequently makes the MACROscope-Microscope system more compact and easier to commercialize. PMID:11023231

  9. Method and apparatus for a multibeam beacon laser assembly for optical communications

    NASA Technical Reports Server (NTRS)

    Biswas, Abhijit (Inventor); Sanji, Babak (Inventor); Wright, Malcolm W. (Inventor); Page, Norman Alan (Inventor)

    2005-01-01

    An optical beacon is comprised of a telescope having a primary focal plane or Coud? focal plane, a plurality of fiber coupled laser sources for generating a plurality of beams, a collimator for collimating the plurality of beams, and optics for combining and focusing the plurality of collimated beams onto the primary or Coud? focal plane of the telescope. The telescope propagates the optical beacon, which is arranged into a ring of incoherent plurality of collimated beams. The apparatus further comprises fiber splitters coupled to each laser source to provide at least eight beams from at least four laser sources. The optics comprises a prism assembly, a combiner lens, a focusing lens and a field lens for focusing the plurality of collimated beams onto the primary focal plane or Coud? focal plane of the telescope.

  10. Fiber optic temperature sensor

    NASA Technical Reports Server (NTRS)

    Sawatari, Takeo (Inventor); Gaubis, Philip A. (Inventor); Mattes, Brenton L. (Inventor); Charnetski, Clark J. (Inventor)

    1999-01-01

    A fiber optic temperature sensor uses a light source which transmits light through an optical fiber to a sensor head at the opposite end of the optical fiber from the light source. The sensor head has a housing coupled to the end of the optical fiber. A metallic reflective surface is coupled to the housing adjacent the end of the optical fiber to form a gap having a predetermined length between the reflective surface and the optical fiber. A detection system is also coupled to the optical fiber which determines the temperature at the sensor head from an interference pattern of light which is reflected from the reflective surface.

  11. Fiber optic temperature sensor

    NASA Technical Reports Server (NTRS)

    Sawatari, Takeo (Inventor); Gaubis, Philip A. (Inventor)

    2000-01-01

    A fiber optic temperature sensor uses a light source which transmits light through an optical fiber to a sensor head at the opposite end of the optical fiber from the light source. The sensor head has a housing coupled to the end of the optical fiber. A metallic reflective surface is coupled to the housing adjacent the end of the optical fiber to form a gap having a predetermined length between the reflective surface and the optical fiber. A detection system is also coupled to the optical fiber which determines the temperature at the sensor head from an interference pattern of light which is reflected from the reflective surface.

  12. A versatile photogrammetric camera automatic calibration suite for multispectral fusion and optical helmet tracking

    NASA Astrophysics Data System (ADS)

    de Villiers, Jason; Jermy, Robert; Nicolls, Fred

    2014-06-01

    This paper presents a system to determine the photogrammetric parameters of a camera. The lens distortion, focal length and camera six degree of freedom (DOF) position are calculated. The system caters for cameras of different sensitivity spectra and fields of view without any mechanical modifications. The distortion characterization, a variant of Brown's classic plumb line method, allows many radial and tangential distortion coefficients and finds the optimal principal point. Typical values are 5 radial and 3 tangential coefficients. These parameters are determined stably and demonstrably produce superior results to low order models despite popular and prevalent misconceptions to the contrary. The system produces coefficients to model both the distorted to undistorted pixel coordinate transformation (e.g. for target designation) and the inverse transformation (e.g. for image stitching and fusion) allowing deterministic rates far exceeding real time. The focal length is determined to minimise the error in absolute photogrammetric positional measurement for both multi camera systems or monocular (e.g. helmet tracker) systems. The system determines the 6 DOF position of the camera in a chosen coordinate system. It can also determine the 6 DOF offset of the camera relative to its mechanical mount. This allows faulty cameras to be replaced without requiring a recalibration of the entire system (such as an aircraft cockpit). Results from two simple applications of the calibration results are presented: stitching and fusion of the images from a dual-band visual/ LWIR camera array, and a simple laboratory optical helmet tracker.

  13. FILAMENT LENGTHS IN STRIATED MUSCLE

    Microsoft Academic Search

    SALLY G. PAGE; H. E. HUXLEY

    1963-01-01

    Filament lengths in resting and excited frog muscles have been measured in the electron microscope, and investigations made of the changes in length that are found under different conditions, to distinguish between those changes which arise during preparation and the actual differences in the living muscles. It is concluded that all the measured differences in filament length are caused by

  14. Utilization of a Curved Focal Surface Array in a 3.5m Wide Field of View Telescope

    NASA Astrophysics Data System (ADS)

    Blake, T.; Faccenda, W.; Lambour, R.; Shah, R.; Smith, A.; Gregory, J. G.; Pearce, E. C.; Woods, D.; Sundbeck, S.; Bolden, M.

    2013-09-01

    Wide field of view optical telescopes have a range for uses in both the astronomical and space surveillance purposes. In designing these systems, a number of factors must be taken into account and design trades accomplished to best balance the performance and cost of the system to meet various program constraints. One design trade that has been discussed of the past decade is the curving of the digital focal surface array to meet the field curvature versus the utilization of optical elements to flatten the field curvature for a more traditional focal plane array. For the Defense Advanced Research Projects Agency (DARPA) 3.5m Space Surveillance Telescope (SST) the choice was made to curve the array to best satisfy the stressing telescope performance parameters, along with programmatic challenges. The results of this design choice led to a system that meets all of the initial program goals and stands ready to dramatically improve the nation's space surveillance capabilities. This paper will discuss the implementation of the curved focal surface array, the performance achieved by the array and the delta cost difference in the curved array versus a typical flat array.

  15. MicroSight Optics

    ScienceCinema

    None

    2013-05-28

    MicroSight is an innovative gunsight technology that allows a marksman's eye to focus on both the front gunsight and the intended target. The MicroSight improves both firearm safety and performance by imaging two objects at different focal distances. The MicroSight was developed at Idaho National Laboratory, and has been licensed by Apollo Optical Systems. You can learn more about INL's research programs at http://www.facebook.com/idahonationallaboratory.

  16. Detection is unaffected by the deployment of focal attention

    PubMed Central

    Moher, Jeff; Ashinoff, Brandon K.; Egeth, Howard E.

    2013-01-01

    There has been much debate regarding how much information humans can extract from their environment without the use of limited attentional resources. In a recent study, Theeuwes et al. (2008) argued that even detection of simple feature targets is not possible without selection by focal attention. Supporting this claim, they found response time (RT) benefits in a simple feature (color) detection task when a target letter's identity was repeated on consecutive trials, suggesting that the letter was selected by focal attention and identified prior to detection. This intertrial repetition benefit remained even when observers were required to simultaneously identify a central digit. However, we found that intertrial repetition benefits disappeared when a simple color target was presented among a heterogeneously (rather than homogeneously) colored set of distractors, thus reducing its bottom–up salience. Still, detection performance remained high. Thus, detection performance was unaffected by whether a letter was focally attended and identified prior to detection or not. Intertrial identity repetition benefits also disappeared when observers were required to perform a simultaneous, attention-demanding central task (Experiment 2), or when unfamiliar Chinese characters were used (Experiment 3). Together, these results suggest that while shifts of focal attention can be affected by target salience, by the availability of excess cognitive resources, and by target familiarity, detection performance itself is unaffected by these manipulations and is thus unaffected by the deployment of focal attention. PMID:23750142

  17. Hepatic focal nodular hyperplasia: angiography, CT, sonography, and scintigraphy

    SciTech Connect

    Rogers, J.V. (Univ. of Washington, Seattle); Mack, L.A.; Freeny, P.C.; Johnson, M.L.; Sones, P.J.

    1981-11-01

    Eleven patients with focal nodular hyperplasia of the liver underwent a combination of radiologic procedures, including sonography, computed tomography (CT), hepatic scintigraphy, and angiography. This paper describes the radiologic findings in this group of patients and reviews the current literature. In the present series, sonography was the most sensitive (100%) method for detection of focal nodular hyperplasia, while CT was able to detect only seven (78%) of nine cases. Arteriographic findings were felt to be characteristic in nine (82%) of 11 cases. Hepatic scintigraphy demonstrated normal colloid uptake in six (55%) of 11 lesions. In this series, an accurate radiologic diagnosis of focal nodular hyperplasia was made in 73% of cases. Hepatic scintigraphy is the pivotal examination. Normal colloid uptake by a focal hepatic mass is virtually diagnostic. However, in the patients in whom the colloid scan shows decreased or absent uptake, angiography may show findings diagnostic of focal nodular hyperplasia in up to 75% of cases, thus avoiding the need for liver biopsy or surgery.

  18. Bayesian source localization via multistep focalization in shallow water

    NASA Astrophysics Data System (ADS)

    Li, Qianqian; Zheng, Bingxiang; Li, Zhenglin

    2012-11-01

    In a realistic application of matched field processing for source localization, the ability to localize an acoustic source is strongly affected by the uncertainty of the environment. However, accurate measurements of the environment are extremely difficult to obtain in large regions of the ocean. Two general approaches, referred to here as one-step focalization and multistep focalization, are used to overcome mismatch and accurately estimate source location with limited a priori environmental information. Focalization maximizes the posterior probability density over the unknown source and environmental parameters. One-step focalization directly estimates all parameters at a single step, while multistep focalization reduces the inversion problem to a sequence of smaller subsets that have fewer parameters to optimize at each stage. This greatly improves the efficiency of the optimization and gives the less sensitive parameters more chances to contribute to the objective function. The broadband signals recorded by a vertical line array during a Yellow Sea experiment are used to verify the validity of the approach.

  19. Impact of surface-polish on the angular and wavelength dependence of fiber focal ratio degradation

    E-print Network

    Eigenbrot, Arthur D; Wood, Corey M

    2012-01-01

    We present measurements of how multimode fiber focal-ratio degradation (FRD) and throughput vary with levels of fiber surface polish from 60 to 0.5 micron grit. Measurements used full-beam and laser injection methods at wavelengths between 0.4 and 0.8 microns on 17 meter lengths of Polymicro FBP 300 and 400 micron core fiber. Full-beam injection probed input focal-ratios between f/3 and f/13.5, while laser injection allowed us to isolate FRD at discrete injection angles up to 17 degrees (f/1.6 marginal ray). We find (1) FRD effects decrease as grit size decreases, with the largest gains in beam quality occurring at grit sizes above 5 microns; (2) total throughput increases as grit size decreases, reaching 90% at 790 nm with the finest polishing levels; (3) total throughput is higher at redder wavelengths for coarser polishing grit, indicating surface-scattering as the primary source of loss. We also quantify the angular dependence of FRD as a function of polishing level. Our results indicate that a commonly a...

  20. When Is Input Salient? An Exploratory Study of Sentence Location and Word Length Effects on Input Processing

    ERIC Educational Resources Information Center

    Carroll, Susanne E.

    2012-01-01

    Sentence position and word length have been claimed to contribute to the perceptual salience of words. The perceptual salience of words in turn is said to predict L2 developmental sequences. Data for such claims come from sentence repetition tasks that required perceptual re-encoding of input and that did not control for focal accent. We used a…