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1

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

DOEpatents

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.

Crandall, David Lynn (Idaho Falls, ID)

2011-08-01

2

Design of a variable-focal-length optical system  

NASA Technical Reports Server (NTRS)

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.

Ricks, D.; Shannon, R. R.

1984-01-01

3

Nano-optical microlens with ultrashort focal length using negative refraction  

E-print Network

Nano-optical microlens with ultrashort focal length using negative refraction B. D. F. Casse,a W. TD finite-difference time-domain simulations. Such ultrarefractive negative-index nano for miniaturization in the microelec- tronics industry and the advent of fiber optics for communi- cations purposes

Sridhar, Srinivas

4

Continuously variable focal length lens  

DOEpatents

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.

Adams, Bernhard W; Chollet, Matthieu C

2013-12-17

5

IMAGES AND OPTICAL INSTRUMENTS 38. INTERPRET We are to find the focal length of a concave mirror given the object and image distance, and then use  

E-print Network

IMAGES AND OPTICAL INSTRUMENTS 38. INTERPRET We are to find the focal length of a concave mirror are consistent with Table 33.1. 41. INTERPRET This problem is about image formation in a concave mirror. We want corresponds to the third case depicted in Table 31.1. The mirror is concave with s image

Ringwald, Frederick A.

6

Microlenses with focal length controlled by chemical processes  

NASA Astrophysics Data System (ADS)

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.

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

2012-05-01

7

Crystal diffraction lens with variable focal length  

DOEpatents

A method and apparatus for altering the focal length of a focusing element o one of a plurality of pre-determined focal lengths by changing heat transfer within selected portions of the element by controlled quantities. Control over heat transfer is accomplished by manipulating one or more of a number of variables, including: the amount of heat or cold applied to surfaces; type of fluids pumped through channels for heating and cooling; temperatures, directions of flow and rates of flow of fluids; and placement of channels.

Smither, Robert K. (Hinsdale, IL)

1991-01-01

8

Crystal diffraction lens with variable focal length  

DOEpatents

A method and apparatus for altering the focal length of a focusing element of one of a plurality of pre-determined focal lengths by changing heat transfer within selected portions of the element by controlled quantities is disclosed. Control over heat transfer is accomplished by manipulating one or more of a number of variables, including: the amount of heat or cold applied to surfaces; type of fluids pumped through channels for heating and cooling; temperatures, directions of flow and rates of flow of fluids; and placement of channels. 19 figures.

Smither, R.K.

1991-04-02

9

Variable-focal length lens using IPMC  

Microsoft Academic Search

We fabricated a liquid lens type variable-focal length lens(VFLL), which is composed of a container with a movable silicon plate having a pupil (diameter: 4 mm) covered by a thin polydimethylsiloxane (PDMS) film, a liquid enclosed in the container and a plural IPMCs fixed above the container for pushing the silicon plate downward. By applying a force to the silicon

Ippei SHIMIZU; Kunitomo KIKUCHI; Shigeki TSUCHITANI

2009-01-01

10

Focal Length Measurements for the National Ignition Facility Large Lenses  

SciTech Connect

The focal length of the spatial filter and final focus lenses for the National Ignition Facility are measured to < {+-} 0.01% using a combination of master lenses and production-oriented techniques for relative focal length.

Parham, T G; McCarville, T J; Johnson, M A; Kiikka, C

2002-01-25

11

Optofluidic lens with tunable focal length and asphericity  

NASA Astrophysics Data System (ADS)

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).

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

2014-09-01

12

Optofluidic lens with tunable focal length and asphericity.  

PubMed

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

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

2014-01-01

13

Optofluidic lens with tunable focal length and asphericity  

PubMed Central

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

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

2014-01-01

14

Optical fibre tapers: focal reduction and magnification  

NASA Astrophysics Data System (ADS)

Optical fibre tapers show great promise as a simple and highly effective means of efficiently coupling broadband light into astronomical instruments. Fibre tapers can replace bulk optics systems such as focal plane reduction and magnification optics by controlling and manipulating image scale and beam angle in a small, robust and cost effective device. However, like any new photonic device fibre tapers must be thoroughly characterised before they can be applied to astronomy. The specific characteristics of importance are the device’s ability to maintain the etendue of the system and to transmit light over a broad wavelength range with minimal loss. In this paper we present the manufacturing technique and preliminary results for the first large taper transition prototype devices manufactured in-house intended for astronomy applications. Characteristics addressed include: beam angle, focal ratio degradation and throughput for devices with a conversion ratio of 5 (5 x focal reduction or magnification) for two taper transition lengths.

Haynes, Dionne M.; Haynes, Roger; Olaya, J. C.; Leon-Saval, Sergio G.

2012-09-01

15

A potential individual cell malignancy indicator: focal length  

NASA Astrophysics Data System (ADS)

The label-free technique of optofluidic intracavity spectroscopy (OFIS) utilizes the optical transmission spectrum of a cell in a microfluidic Fabry-Pérot (F-P) cavity to distinguish cells from cancerous cell lines and baseline normal blood cells. The classification between canine hemangiosarcoma (HSA) cancer cells and monocytes in canine normal peripheral blood mononuclear cells (PBMCs) had been demonstrated with 95% sensitivity and 98% specificity. Now with a new optical model that treats the cell settled at the bottom of the cavity as a thin lens, the focal length of cells was extracted and used as an individual cell malignancy indicator.

Wang, Weina; Lear, Kevin L.

2011-03-01

16

Long Focal Length Large Mirror Fabrication System  

NASA Technical Reports Server (NTRS)

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.

Bennett, H. E.

2003-01-01

17

Acoustic lens with variable focal length for photoacoustic microscopy  

NASA Astrophysics Data System (ADS)

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.

Song, Chaolong; Xi, Lei; Jiang, Huabei

2013-11-01

18

Liquid crystal-based square lens array with tunable focal length.  

PubMed

We demonstrate a liquid crystal (LC)-based square lens array with two focusing modes according to the polarization state of the input light. The homogeneously aligned LC layer is placed on an array of static square lenses fabricated using a photo-curable polymer whose refractive index is matched with the refractive index of the LC. For the input beam polarized parallel to the easy axis of the LC, the focal length is varied with the applied voltage from a few meters to 21 mm which corresponds to the focal length of the static lens. For the perpendicularly polarized input beam, the focal length is independent of the applied voltage and remains constant. The two focusing effects with high optical performance over fully activated areas are useful for polarization-dependent imaging systems and three-dimensional displays in projection and integral imaging. PMID:24663622

Kim, Jiyoon; Kim, Jonghyun; Na, Jun-Hee; Lee, Byoungho; Lee, Sin-Doo

2014-02-10

19

Exhaustive linearization for robust camera pose and focal length estimation.  

PubMed

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

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

2013-10-01

20

Exhaustive Linearization for Robust Camera Pose and Focal Length Estimation.  

PubMed

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

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

2013-01-30

21

Effects of environment factors on imaging performance of long focal length space camera  

NASA Astrophysics Data System (ADS)

In course of developing, testing, launching and working in orbit, Space camera has to undergo the shock of external loads and changing environment. The optical performance of a long focal length space camera is largely determined by external mechanical loads and ambient temperature. The performance of the camera is a result of the interaction between environment factors. The performance of the optical system should be making an accurate forecast when a modern optical instrument is designed. In this paper, the research methods are reviewed firstly. Then the related technologies are described. The analysis methods of environment temperature and structural characteristics effecting space camera imaging performance are also discussed.

Guo, Quanfeng; Jin, Guang; Dong, Jihong; Li, Wei; Li, Yanchun; Wang, Haiping; Wang, Kejun; Zhao, Weiguo

2012-10-01

22

Optical links for cryogenic focal plane array Alan R. Johnston  

E-print Network

Optical links for cryogenic focal plane array readout Alan R. Johnston Duncan T. H. Liu, MEMBER@jplopto.jpl.nasa.gov 1 Introduction Optical instruments employing cryogenic focal plane arrays must minimize power dissipation on the focal plane. Because cooler power efficiency is low at cryogenic temperatures, reduction

Fossum, Eric R.

23

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

NASA Astrophysics Data System (ADS)

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.

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

2007-01-01

24

Short-focal-length compound refractive lenses for x-rays  

SciTech Connect

We have fabricated and tested short focal-length compound refractive lenses (CRLs) composed of micro-bubbles embedded in epoxy. The bubbles were formed in epoxy inside glass capillaries. The interface between the bubbles formed 90 to 196 spherical bi-concave microlenses reducing the overall focal length inversely by the number of lenses. When compared with CRLs manufactured using other methods, the micro-bubble lenses have shorter focal lengths, better imaging, and focusing qualities with higher transmissions and gains for moderate energy x-rays (e.g. 7-12 keV). We used beamline 2-3 at the Stanford Synchrotron Radiation Laboratory (SSRL) to measure focal lengths between 100-150 mm and absorption apertures between 90 to 120 {micro}m. Transmission profiles were measured giving, for example, a peak transmission of 27% for a 130-mm focal length CRL at 8 keV. The focal-spot sizes were also measured yielding, for example, an elliptical spot of 5 x 14-{micro}m{sup 2} resulting from an approximate 80-fold demagnification of the 0.44 x 1.7 mm{sup 2} source. The measured gains in intensity over that of unfocused beam were between 9 and 26. Theoretical gain calculations that include spherical aberrations show that these values are reasonable. The micro-bubble technique opens a new opportunity for designing lenses in the 8-9 keV range with focal lengths less than 30-40 mm.

Dudchik, Y.I.; Kolchevsky, N.N.; Komarov, F.F.; Piestrup, M.A.; Cremer, J.T.; Gary, C.K.; Pantell, R.H. (Adelphi)

2005-08-15

25

Measuring the lens focal length by laser reflection-confocal technology.  

PubMed

A laser reflection-confocal focal-length measurement (LRCFM) is proposed for the high-accuracy measurement of lens focal length. LRCFM uses the peak points of confocal response curves to precisely identify the lens focus and vertex of the lens last surface. LRCFM then accurately measures the distance between the two positions to determine the lens focal length. LRCFM uses conic fitting, which significantly enhances measurement accuracy by inhibiting the influence of environmental disturbance and system noise on the measurement results. The experimental results indicate that LRCFM has a relative expanded uncertainty of less than 0.0015%. Compared with existing measurement methods, LRCFM has high accuracy and a concise structure. Thus, LRCFM is a feasible method for high-accuracy focal-length measurements. PMID:23736337

Yang, Jiamiao; Qiu, Lirong; Zhao, Weiqian; Shao, Rongjun; Li, Zhigang

2013-06-01

26

Optical links for cryogenic focal plane array readout  

NASA Astrophysics Data System (ADS)

An optical link can provide an interface channel for the focal-plane array that is immune to electromagnetic interference (EMI) and can lower the heat load on the dewar. Our approach involves the use of fiber-optics and an on-focal-plane optical modulator to provide an interface to the focal-plane array (FPA). The FPA drives the modulator with an electrical signal. We evaluated specially fabricated AlGaAs/GaAs multiple quantum well (MQW) optical modulators, operating near 840 nm, for analog modulation, and we have used the results to calculate the performance of an optical interface link using experimentally determined device parameters. Link noise and dynamic range for an analog link were estimated from a separate experiment using pigtailed fiber components. The performance of the MQW modulator system is compared to alternative strategies. Significant improvement in performance in comparison to conventional electronic interfaces appears to be possible.

Johnston, Alan R.; Liu, Duncan T.; Forouhar, Siamak; Lutes, George F.; Maserjian, Joseph L.; Fossum, Eric R.

1993-10-01

27

Optical links for cryogenic focal plane array readout  

NASA Astrophysics Data System (ADS)

An optical link can provide an interface channel for a focal plane array that is immune to electro-magnetic interference and can lower the heat load on the dewar. Our approach involves the use of fiber optics and an on-focal-plane optical modulator to provide an interface to the focal plane array (FPA). The FPA drives the modulator with an electrical signal. We evaluated specially fabricated AlGaAs/GaAs multiple-quantum well (MQW) optical modulators, operating near 840 nm, for analog modulation, and we have used the results to calculate the performance of an optical interface link using experimentally determined device parameters. Link noise and dynamic range for an analog link were estimated from a separate experiment using pigtailed fiber components. The performance of the MQW modulator system is compared to alternative strategies. Significant improvement in performance in comparison to conventional electronic interfaces appears to be possible.

Johnston, Alan R.; Liu, Duncan T.; Forouhar, Siamak; Lutes, George F.; Maserjian, Joseph L.; Fossum, Eric R.

1994-06-01

28

Bioluminescence microscopy using a short focal-length imaging lens.  

PubMed

Bioluminescence from cells is so dim that bioluminescence microscopy is performed using an ultra low-light imaging camera. Although the image sensor of such cameras has been greatly improved over time, such improvements have not been made commercially available for microscopes until now. Here, we customized the optical system of a microscope for bioluminescence imaging. As a result, bioluminescence images of cells could be captured with a conventional objective lens and colour imaging camera. As bioluminescence microscopy requires no excitation light, it lacks the photo-toxicity associated with fluorescence imaging and permits the long-term, nonlethal observation of living cells. Thus, bioluminescence microscopy would be a powerful tool in cellular biology that complements fluorescence microscopy. PMID:24386879

Ogoh, K; Akiyoshi, R; May-Maw-Thet; Sugiyama, T; Dosaka, S; Hatta-Ohashi, Y; Suzuki, H

2014-03-01

29

Microlenses with tuned focal characteristics for optical wireless imaging  

NASA Astrophysics Data System (ADS)

Microlenses are fabricated and investigated for integrated imaging applications. The microlenses are fabricated by an in situ polymer electro-dispensing technique that enables user-controlled microlens sizes and shapes, by direct-dispensing and voltage-tuning with a metal micro-needle tip in a filler solution. Theoretical and experimental analyses are carried out for three limiting-cases of electro-dispensed microlenses: an acute-angle microlens with a 30° contact angle, a right-angle microlens with a 90° contact angle, and an obtuse-angle microlens with a 120° contact angle. It is found that the right-angle microlens, with a 500 ?m diameter, yields an especially short focal length (700 ?m) and exceedingly large numerical aperture (0.533). These characteristics can meet the needs of emerging applications, such as optical wireless devices, which demand compact device integration and broad field-of-view imaging. The microlenses are tested in optical wireless imaging receivers, for signal-to-noise ratio performance, and it is found that the right-angle microlens can offer significant (10 dB) performance enhancements.

Jin, Xian; Guerrero, Daniel; Klukas, Richard; Holzman, Jonathan F.

2014-07-01

30

Cryogenic focal plane flatness measurement with optical zone slope tracking  

NASA Astrophysics Data System (ADS)

We describe a non-contact optical measurement method used to determine the surface flatness of a cryogenic sensor array developed for the JDEM mission. Large focal planes envisioned for future visible to near infra-red astronomical large area point-source surveys such as JDEM, WFIRST, or EUCLID must operate at cryogenic temperatures while maintaining focal plane flatness within a few 10's of ?m over half-meter scales. These constraints are imposed by sensitivity conditions that demand low noise observations from the sensors and the large-field, fast optical telescopes necessary to obtain the science yield. Verifying cryogenic focal plane flatness is challenging because ?m level excursions need to be measured within and across many multi-cm sized sensors using no physical contact and while situated within a high-vacuum chamber. We have used an optical metrology Shack-Hartmann scheme to measure the 36x18 cm focal plane developed for the JDEM mission at the Lawrence Berkeley National Laboratory. The focal plane holds a 4x8 array of CCDs and HgCdTe detectors. The flatness measurement scheme uses a telescope-fed micro-lens array that samples the focal plane to determine slope changes of individual sensor zones.

Edelstein, Jerry; Sirk, Martin; Jelinsky, Patrick N.; Besuner, Robert W.; Hoff, Matthew; Perry, Paul; Heetderks, Henry D.; Bebek, Christopher J.; Levi, Michael E.

2011-10-01

31

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

E-print Network

Great (Focal) Lengths Project 2. Due 11:59PM on Friday, March 1, 2013. Staff email: cs194-23@imail, such as a loud sound. You might use this as an opportunity to take a photograph of a balloon popping, a water

O'Brien, James F.

32

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

PubMed

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

Zhu, Xianchang; Hu, Song; Zhao, Lixin

2014-10-10

33

A branch-and-bound algorithm for globally optimal camera pose and focal length  

Microsoft Academic Search

This paper considers the problem of finding the global optimum of the camera rotation, translation and the focal length given a set of 2D–3D point pairs. The global solution is obtained under the L-infinity optimality by a branch-and-bound algorithm. To obtain the goal, we firstly extend the previous branch-and-bound formulation and show that the image space error (pixel distance) may

Kyuhyoung Choi; Subin Lee; Yongduek Seo

2010-01-01

34

Long focal-length measurement using divergent beam and two gratings of different periods.  

PubMed

A new accurate method for long focal-length measurement based on Talbot interferometry is proposed. A divergent beam and two Ronchi gratings of different periods are employed, as the alternative of the collimated beam and two identical gratings, to achieve higher measurement accuracy. Moreover, with divergent beam, lenses of large aperture can be easily measured without scanning, which is required when it comes to traditional collimated beam. Numerical analysis and experiments were carried out. The results demonstrate the proposed method features remarkably high accuracy and repeatability. PMID:25402033

Luo, Jia; Bai, Jian; Zhang, Jinchun; Hou, Changlun; Wang, Kaiwei; Hou, Xiyun

2014-11-17

35

Scaling of the generation of high-order harmonics in large gas media with focal length  

SciTech Connect

We present theoretical and experimental results on high-order harmonic generation in a low-density few-centimeter-long gas medium (L{sub med}{<=} 10 cm). We study the dependence with focal length of harmonic efficiency. Theoretically, we consider in detail the generation of the 25th harmonic of a short pulse Ti:sapphire laser in argon. Within the strong-field approximation for the atomic dipole, and a complete account of the macroscopic propagation, we compute the number of photons produced as a function of the medium parameters and the focusing conditions. The simulations show that, at constant intensity, the emission of the 25th harmonic scales with the focal length as {approx}f{sup 4} at low pressure (P=2 Torr) and as {approx}f{sup 6} at higher pressure (P=5 Torr). At constant laser energy, we find that the harmonic signal scales approximately as f{sup 2} at low pressure and as f{sup 4} at higher pressure. Those numerical results are compared with experimental data.

Boutu, W.; Auguste, T.; Caumes, J. P.; Carre, B. [Service des Photons, Atomes et Molecules, CEA-Saclay, F-91191 Gif-sur-Yvette Cedex (France); Merdji, H. [Service des Photons, Atomes et Molecules, CEA-Saclay, F-91191 Gif-sur-Yvette Cedex (France); PULSE Institute for Ultrafast Energy Science, Stanford Linear Accelerator Center, Stanford University, 2575 Sand Hill Road, Menlo Park, California 94025 (United States)

2011-11-15

36

A high-density integrated optical focal plane positioning system  

NASA Astrophysics Data System (ADS)

Modern multi-spectral sky survey requires the use of greater quantity and smaller size of the fiber positioner. This paper presents a high-density integrated optical focal plane positioning system, which includes 150 groups fiber positioning module and a 1 meter diameter honeycomb-shaped focal plane framework in that have about 150 hexagonal hole. Each module has a pedestal includes 37 holes and 37 fiber positioner of 11.8 mm diameter. 37 fiber positioner integrated can greatly reduce the difficulty of the design and installation. The modular structure also facilitates maintenance and replacement in the field of telescope, and greatly reduce the difficulty of the drive system design. Numerical simulation results show that: the honeycomb-shaped focal plane framework whose thickness is 100mm and who is in a variety of working positions and load conditions, its maximum deformation is about 0.02mm. This meet the needs of the general astronomical telescopes. The positioning accuracy of test 12mm diameter fiber positioner is about 0.04 mm, and it is expected to reach 0.01mm if have the closed-loop control.

Hu, Hongzhuan; Wang, Jianping; Liu, Zhigang; Zhou, Zengxiang; Zhai, Chao; Chu, Jiaru

2014-07-01

37

LWIR QWIP focal plane array mounting with cryogenic optical system  

NASA Astrophysics Data System (ADS)

We present progress on developing a mechanical and thermal isolation package for maintaining multi-stage temperature control for various parts of a dewar package. Our long-wave QWIP focal plane is maintained at 40K while our optics package, which is at close proximity (~2mm) to the FPA, is maintained at 80K. Radiative baffling is controlled at acceptable levels using high conductance heat sinks, while conductance loads are minimized using proper insulating materials (polyimide synthetics) in combination with materials to preserve high structural stiffness (titanium, invar). Furthermore, the optics package is held at low cryogenic temperatures only ~ 6mm from the ZnSe dewar window. An effort is made to keep the complete electro-optical system at these low temperatures independently using only a single 10W low EM-noise closed cycle cryocooler. Proper geometry is defined which takes into account thermal symmetries and mechanical structural stability, while maintaining the necessary external 300K heat sinks. Both conductance and radiative loading on the opto-mechanical structure are examined using finite element analysis and proper heat sinking is established to thermally isolate the optics within the dewar jacket while maintaining proper structural stability. A custom LCC is designed which maximizes the thermal expansion budget between the FPA and optics package, while necessary structural mounting of the electronics boards are coupled with the dewar coldfinger.

Johnson, William R.; Gunapala, Sarath; Mumolo, Jason; Johnson, Dean

2007-09-01

38

Focal-Plane Image and Beam Quality Sensors for Adaptive Optics  

E-print Network

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

Cauwenberghs, Gert

39

Cryogenic focal plane flatness measurement with optical zone slope Jerry Edelstein1  

E-print Network

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

California at Berkeley, University of

40

Optical Arc-Length Sensor For TIG Welding  

NASA Technical Reports Server (NTRS)

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.

Smith, Matthew A.

1990-01-01

41

Performance evaluation of electro-optical focal planes for aerial reconnaissance  

Microsoft Academic Search

The Optical Systems Division of Itek Corporation has developed techniques for analytical and experimental evaluation of image performance that have proven especially well suited to verifying the design of electro-optical focal planes. Analytical techniques used in the design process include computer programs that calculate focal plane signal parameters versus scene and camera system parameters. The results are applied to calibrated

W. J. Abrams

1978-01-01

42

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

NASA Technical Reports Server (NTRS)

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

Reinert, Jason

2004-01-01

43

Focal Plane Wavefront Sensing Using Residual Adaptive Optics Speckles  

NASA Astrophysics Data System (ADS)

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.

Codona, Johanan L.; Kenworthy, Matthew

2013-04-01

44

An Optical Method for Measurements of Sound Waveform at the Focal Point of Focused Ultrasound  

Microsoft Academic Search

The sound waveform of focused ultrasound is measured at the focal point using optical beam refraction. Instead of a narrow light beam, an ordinary Gaussian laser beam whose diameter is 1 mm is used. An iris which has a small aperture is also applied to observe the refracted light. The signal obtained by the optical method was in agreement with

Hironaka Miyaki; Yoshiaki Watanabe

1999-01-01

45

Spot size and effective focal length measurements for a fast axial flow CO{sub 2} laser  

SciTech Connect

An evaluation of the variation in focal plane position and spot size for a 1,650 W fast axial flow CO{sub 2} laser was performed. Multiple measurements of the focused beam were taken at stepped intervals along the beam axis to create a composite representation of the focus region. Measurements were made at several power levels from low to full power for each of five nominally identical lenses. It was found that as laser output power increases, the minimum focused spot radius increases, and the position of minimum focus shifts toward the laser resonator. These effects were attributed to observed variations in the diameter of the beam entering the focusing lens. For the ZnSe (f = 127 mm) lenses examined, variations in spot radius and focal plane position were seen. Lenses with high rated absorption had a larger variation in spot size and effective focal length than those with low absorption. Lenses that had previously been degraded by welding had the greatest variation.

Steele, R.J. [Naval Air Warfare Center, China Lake, CA (United States); Fuerschbach, P.W.; MacCallum, D.O. [Sandia National Labs., Albuquerque, NM (United States)

1997-12-31

46

Optical links for cryogenic focal-plane array readout Alan R. Johnston, Duncan TH. Liu, Siamak Forouhar,  

E-print Network

Optical links for cryogenic focal-plane array readout Alan R. Johnston, Duncan TH. Liu, Siamak cryogenic focaiplane arrays must minimize power dissipation on the focal.plane. Since cooler power efficiency is low at cryogenic temperatures, reduction of focal-plane power has strong leverage in re. ducing

Fossum, Eric R.

47

Measurement of Trap Length for an Optical Trap  

NASA Technical Reports Server (NTRS)

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.

Wrbanek, Susan Y.

2009-01-01

48

Generation of super-length optical needle by focusing hybridly polarized vector beams through a dielectric interface.  

PubMed

A super-length optical needle (~14?) of strong transversally polarized field with homogeneous intensity along the optical axis and subdiffraction beam size (~0.9?) can be generated by focusing a hybridly polarized vector beam through a dielectric interface with an annular high-NA lens. Moreover, it is found that the polarization of the cross section near the focal plane is radial variant. Such a nondiffracting optical needle may have applications in atom-optical experiments, such as with atom trap and atom switches. PMID:23381238

Hu, Kelei; Chen, Ziyang; Pu, Jixiong

2012-08-15

49

Relative contributions of scattering, diffraction and modal diffusion to focal ratio degradation in optical fibres  

NASA Astrophysics Data System (ADS)

Focal ratio degradation (FRD) is a major contributor to light loss in astronomical instruments employing multimode optical fibres. We present a powerful diagnostic model that uniquely quantifies the various sources of FRD in multimode fibres. There are three main phenomena that can contribute to FRD: scattering, diffraction and modal diffusion. We propose a Voigt FRD model where the diffraction and modal diffusion are modelled by the Gaussian component and the end-face scattering is modelled by the Lorentzian component. The Voigt FRD model can be deconvolved into its Gaussian and Lorentzian components and used to analyse the contribution of each of the three major components. We used the Voigt FRD model to analyse the FRD of modern astronomical grade fibre for variations in (i) end-face surface roughness, (ii) wavelength, (iii) fibre length and (iv) external fibre stress. The elevated FRD we observed was mostly due to external factors, i.e. fibre end effects such as surface roughness, subsurface damage and environmentally induced microbending caused by the epoxy, ferrules and fibre cable design. The Voigt FRD model has numerous applications such as a diagnostic tool for current fibre instrumentation that show elevated FRD, as a quality control method for fibre manufacture and fibre cable assembly and as a research and development tool for the characterization of new fibre technologies.

Haynes, D. M.; Withford, M. J.; Dawes, J. M.; Lawrence, J. S.; Haynes, R.

2011-06-01

50

Smart polymers containing substituted coumarin side groups enable photo-induced tuning of focal length of intraocular lenses  

NASA Astrophysics Data System (ADS)

Over the past 100 years medicine evolved continuously, which can clearly be seen in the rising average of life expectancy. But as the population becomes older and older the number of old age diseases increases. Cataract is such an old age disease and worldwide the number one reason for blindness. Implantation of IOL's is up-to-date the only possibility to restore vision. In this study we present novel polymers containing derivatized coumarins in the side chains as smart materials for IOL manufacturing. These materials enable tuning of the focal length of an already implanted IOL by 2 diopters via photo induced dimerization and cleavage of the coumarin side groups respectively. The advantages of these new polymers are increased dimerization rates while decreasing the energy dose needed for photochemical dimerization of the coumarin side groups.

Schraub, Martin; Hampp, Norbert

2011-03-01

51

On the use of clessidra prism arrays in long-focal-length X-ray focusing.  

PubMed

Clessidra (hour-glass) X-ray lenses have an overall shape of an old hour glass, in which two opposing larger triangular prisms are formed of smaller identical prisms or prism-like objects. In these lenses, absorbing and otherwise optically inactive material was removed with a material-removal strategy similar to that used by Fresnel in the lighthouse lens construction. It is verified that when the single prism rows are incoherently illuminated they can be operated as independent micro-lenses with coinciding image positions for efficient X-ray beam concentration. Experimental data for the line width and the refraction efficiency in one-dimensional focusing are consistent with the expectations. Imperfections in the structures produced by state-of-the-art deep X-ray lithography directed only 35% of the incident intensity away from the image and widened it by just 10% to 125 microm. An array of micro-lenses with easily feasible prism sizes is proposed as an efficient retrofit for the refocusing optics in an existing beamline, where it would provide seven-fold flux enhancement. PMID:18552435

Jark, Werner; Matteucci, Marco; Menk, Ralf Hendrik

2008-07-01

52

Optical path-length matrix method for estimating skin spectrum  

NASA Astrophysics Data System (ADS)

In this article, we propose a new method—the optical path-length matrix method (OPLM)—as a faster alternative to the Monte Carlo for multi-layered media (MCML), which is often used to simulate the skin spectrum. Theoretically, peripheral oxygen saturation can be estimated by iterating MCML, but it is not a realistic strategy because it requires huge computation time. The optical path-length matrix is obtained as the probabilistic density histograms of the optical path length in skin using MCML, and once the matrix is obtained, skin spectral reflectance can be calculated by accumulating all combinations of elements in the matrix and by setting an absorption coefficient based on the Beer-Lambert law. The computational time of OPLM was approximately 26,000 times faster than that of MCML.

Yamamoto, Satoshi; Fujiwara, Izumi; Yamauchi, Midori; Tsumura, Norimichi; Ogawa-Ochiai, Keiko

2012-11-01

53

Adaptive optics operation with focal wavefront sensor in a coronagraph for direct observation of exoplanets  

NASA Astrophysics Data System (ADS)

A stellar coronagraph system for direct observations of extra solar planets is under development by combining unbalanced nulling interferometer (UNI), adaptive optics, and a focal plane mask coronagraph1,2,3,4,5,6. It can reach a high contrast as using ?/10000 precision optics by ?/1000 quality ones. However, a sufficient high contrast is not obtained yet in the experiment before. It is thought that the remained speckle noise at the final coronagraph focal plane detector are produced by a "non-common path error" of ?/100 level, which is a wavefront error of the coronagraph different from that of a wavefront sensor (WFS) of adaptive optics, even when the WFS indicates ?/1000 conversion. The non-common path error can be removed by the dark zone method that is the way of wavefront correction by wavefront sensing at the final focal plane detector, although it has an issue of operation for very faint targets because of a slow feedback loop. In the present paper, we describe that our coronagraph system becomes practically higher contrast by upgrading the control method of deformable mirror (DM) with the WFS assisted by final focal plane wavefront sensing method. We accomplished contrast of 8×10-7 relative to the star in experiment.

Oya, Masahito; Nishikawa, Jun; Horie, Masaaki; Sato, Kazuma; Fukase, Masao; Murakami, Naoshi; Kotani, Takayuki; Kumagai, Shiomi; Tamura, Motohide; Tanaka, Yosuke; Kurokawa, Takashi

2014-08-01

54

Measurement of the Length of an Optical Trap  

NASA Technical Reports Server (NTRS)

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.

Wrbanek, Susan Y.

2010-01-01

55

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

PubMed

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 23mm, whereas TOFs with a constant taper angle of 2mrad reach 99.6% transmission for a 63mm TOF length. PMID:25402084

Nagai, Ryutaro; Aoki, Takao

2014-11-17

56

Phase Length Optical Phase-Locked-Loop Sensor  

NASA Technical Reports Server (NTRS)

The invention is a device that provides a high resolution measurement of the change in optical phase length from the device optical system source to an optical reflector. The invention consists of a optical phase locked loop that uses a laser beam as a carrier of an intensity modulated energy source. The novelty of the invention appears to lie in the overall combination of elements which provide high resolution without loss of wide dynamic range. The invention does not depend on coherent reflection from a target, and thus can measure targets that do not have special preparation or corner reflectors. The use of carrier modulation achieves high resolution without the problems of high speed pulse duration systems. Thus the invention has the advantages of simplicity, low cost, and small size without sacrificing resolution.

Heyman, Joseph S. (inventor)

1988-01-01

57

Interferometric sensors based on sinusoidal optical path length modulation  

NASA Astrophysics Data System (ADS)

Sinusoidal optical path length modulation of the reference or the measurement arm of an interferometer is a technique which is a fast alternative to white light or phase shifting interferometry. In this paper three different sensors using this periodical modulation are presented. In addition, signal processing algorithms based on Discrete Fourier Transform, Hilbert Transform and parameter estimation are analyzed. These algorithms are used to obtain measurement results which demonstrate the capabilities of the presented interferometric sensors.

Knell, Holger; Schake, Markus; Schulz, Markus; Lehmann, Peter

2014-05-01

58

All-optical payload envelope detection for variable length 40-gb\\/s optically labeled packets  

Microsoft Academic Search

We demonstrate a new technique to all-optically identify the precise temporal locations and durations of the payloads of optical packets consisting of a variable length 40-Gb\\/s return-to-zero payload and 10-Gb\\/s nonreturn-to-zero label. The all-optically generated payload envelope signal can be used to erase the original optical label and rewrite a new label. The recovered payload envelope has 300-ps rise time

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

2006-01-01

59

Focal activation of cells by plasmon resonance assisted optical injection of signaling molecules.  

PubMed

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 (Ca(2+)) release from intracellular stores. Upon optical injection of IP3 or AdA at doses above the activation threshold, we observed increases in cytosolic Ca(2+) concentration within the injected cell initiating the propagation of a Ca(2+) wave throughout nearby cells. As confirmed by octanol-induced inhibition, the intercellular Ca(2+) 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

Orsinger, Gabriel V; Williams, Joshua D; Romanowski, Marek

2014-06-24

60

Remote focal scanning optical projection tomography with an electrically tunable lens  

PubMed Central

We describe a remote focal scanning technique for optical projection tomography (OPT) implemented with an electrically tunable lens (ETL) that removes the need to scan the specimen or objective lens. Using a 4× objective lens the average spatial resolution is improved by ?46% and the light collection efficiency by a factor of ?6.76, thereby enabling increased acquisition speed and reduced light dose. This convenient implementation is particularly appropriate for lower magnifications and larger sample diameters where axial objective scanning would encounter problems with speed and stability. PMID:25360356

Chen, Lingling; Kumar, Sunil; Kelly, Douglas; Andrews, Natalie; Dallman, Margaret J.; French, Paul M. W.; McGinty, James

2014-01-01

61

Holographic illumination in optical readout focal plane array infrared imaging system.  

PubMed

An IR imaging system based on a microelectromechanical system (MEMS) microcantilever is uncooled, low-cost, and more reliable than traditional systems. However, it is difficult to avoid unwanted shape distortions in fabrication, which can degrade image quality in many ways, so we use holography to compensate for these shape distortions in an optical readout focal plane array (FPA) IR imaging system. The experiment shows that it is a feasible way to improve system performance, especially when it is too difficult to perfect the techniques of an FPA fabrication. PMID:19927206

Liu, Ming; Zhao, Yuejin; Dong, Liquan; Yu, Xiaomei; Liu, Xiaohua; Hui, Mei; You, Jianfeng; Yi, Yuliang

2009-11-15

62

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

NASA Astrophysics Data System (ADS)

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.

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

2013-11-01

63

Optical Scattering Lengths in Large Liquid-Scintillator Neutrino Detectors  

E-print Network

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 PXE, LAB, and Dodecane which are under discussion for next-generation experiments like SNO+, Hanohano, or LENA. Results comprise the wavelength range from 415 to 440nm. 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.

Michael Wurm; Franz von Feilitzsch; Marianne Goeger-Neff; Martin Hofmann; Tobias Lachenmaier; Timo Lewke; Teresa Marrodan Undagoitita; Quirin Meindl; Randoplh Moellenberg; Lothar Oberauer; Walter Potzel; Marc Tippmann; Sebastian Todor; Christoph Traunsteiner; Juergen Winter

2010-04-06

64

Clinical and optic coherence tomography findings of focal choroidal excavation in Chinese patients  

PubMed Central

Background To describe the clinical and optical coherence tomography (OCT) features of focal choroidal excavation in Chinese patients. Methods Retrospectively, thirty-seven eyes (in 31 patients) that demonstrated focal choroidal excavation on spectral-domain OCT were collected. Their clinical characteristics and other features were also collected and analyzed. Results In total, 42 focal choroidal excavations were identified in 31 patients, including 25 unilateral and 6 bilateral (37 eyes). The abnormal changes in these eyes with choroidal excavation were more prominent at the outer part of the neuro-retina, the retinal pigment epithelium (RPE) and the choroid. The average transverse diameter and depth of the excavations were 670.8 ?m and 106.9 ?m, respectively. In addition to the conforming and nonconforming types, the excavations could also be classified into 2 types according to their shape: type 1 – small with a sharp, cut-down contour; and type 2 – slightly larger with a gradual edge. The transverse diameter/depth ratio of the two types were significantly different (type1: 4.57?±?1.65, type 2: 10.0?±?5.2; p?=?0.000). Four central serous chorioretinopathy (CSCR) cases were confirmed by fluorescein angiography; in these cases, the retinal detachment was larger than the area of excavation, and the inner segment/outer segment (IS/OS) and external limiting membrane (ELM) were above those of the normal part. Concomitant CNV was also found in another 2 cases. Conclusions Focal choroidal excavation was not uncommon in Chinese patients. The choroid and the RPE at the excavation were impaired or vulnerable to other damage. Additionally, OCT might be useful in the differentiation between nonconforming excavations and ones with CSCR. PMID:24886645

2014-01-01

65

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

NASA Astrophysics Data System (ADS)

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.

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

66

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

E-print Network

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.

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

67

Calibration method for division of focal plane polarimeters in the optical and near-infrared regime  

NASA Astrophysics Data System (ADS)

Advances in nanofabrication allow for the creation of metallic nanowires acting as linear polarizers in the visible and near infrared regime. The monolithic integration of silicon detectors and pixelated nanowire metallic polarization filters allows for an efficient realization of high resolution polarization imaging sensors. These silicon sensors, known as division of focal plane polarimeters, capture polarization information of the imaged environment from ~400nm to 1050nm wavelength. The performance of the polarization sensor can be degraded by both irregularities in the fabrication of the nanowires and possible misalignment errors during the final deposition of the optical nanowire filters on the surface of the imaging sensor. In addition, electronic offsets due to the readout circuitry, electronic crosstalk, and optical crosstalk will also negatively affect the quality of the polarization information. Partial compensation for many of these post-fabrication errors can be accomplished through the use of a camera calibration routine. This paper will describe one such routine, and show how its application can increase the quality of measurements in both the degree of linear polarization and angle of polarization in the visible spectrum. The imaging array of the division of focal plane polarimeter is segmented into two by two blocks of superpixels. The calibration method chooses one of the four pixels as a reference, and then a gain and offset for each of the remaining three is computed based on this reference. The output is a calibration matrix for each pixel in the image array.

York, Timothy; Gruev, Viktor

2011-06-01

68

Optics  

NSDL National Science Digital Library

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.

Christian, Wolfgang; Belloni, Mario

2008-02-09

69

Laser Metrology for an Optical-Path-Length Modulator  

NASA Technical Reports Server (NTRS)

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.

Gursel, Yekta

2005-01-01

70

Investigation of Radiation Collection by InSb Infrared Focal-Plane Arrays with Micro-optic Structures  

NASA Astrophysics Data System (ADS)

Three designs of micro-optic structures have been analyzed by two-dimensional simulation. Compared with traditional spherical microlenses, the micro-optic structures have the same ability to collect radiation and do not have the disadvantages of traditional microlenses. In our analysis the micro-optic structures are simple grooved notches above the space between two adjacent mesas. We also investigate the characteristics of InSb focal-plane arrays with both spherical microlenses and micro-optic structures under oblique incident radiation. Empirical formulas were derived to describe the response and crosstalk as a function of incident radiation angle. Our results show that the micro-optic structures can be effectively used in radiation collection for InSb infrared focal-plane arrays.

Guo, N.; Hu, W. D.; Chen, X. S.; Lei, W.; Lv, Y. Q.; Zhang, X. L.; Si, J. J.; Lu, W.

2013-11-01

71

Focal-plane wavefront sensing with high-order adaptive optics systems  

NASA Astrophysics Data System (ADS)

We investigate methods to calibrate the non-common path aberrations at an adaptive optics system having a wavefront-correcting device working with an extremely high resolution (larger than 150x150 correcting elements). We use focal-plane images collected successively, the corresponding phase-diversity information and numerically efficient algorithms to calculate the required wavefront updates. Different approaches are considered in numerical simulations, and laboratory experiments are shown to confirm the results. We compare the performances of the standard Gerchberg-Saxton algorithm, Fast and Furious (use of small-phase assumption to take advantage of linearisation) and recently proposed phase-retrieval methods based on convex optimisation. The results indicate that the calibration task is easiest with algorithms similar to Fast and Furious, at least in the framework we considered.

Korkiakoski, Visa; Keller, Christoph U.; Doelman, Niek; Kenworthy, Matthew; Otten, Gilles; Verhaegen, Michel

2014-08-01

72

Focal-plane wavefront sensing with high-order adaptive optics systems  

E-print Network

We investigate methods to calibrate the non-common path aberrations at an adaptive optics system having a wavefront-correcting device working at an extremely high resolution (larger than 150x150). We use focal-plane images collected successively, the corresponding phase-diversity information and numerically efficient algorithms to calculate the required wavefront updates. The wavefront correction is applied iteratively until the algorithms converge. Different approaches are studied. In addition of the standard Gerchberg-Saxton algorithm, we test the extension of the Fast & Furious algorithm that uses three images and creates an estimate of the pupil amplitudes. We also test recently proposed phase-retrieval methods based on convex optimisation. The results indicate that in the framework we consider, the calibration task is easiest with algorithms similar to the Fast & Furious.

Korkiakoski, Visa; Doelman, Niek; Kenworthy, Matthew; Otten, Gilles; Verhaegen, Michel

2014-01-01

73

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

74

Calibration of optical tweezers with positional detection in the back focal plane  

SciTech Connect

We explain and demonstrate a new method of force and position calibrations for optical tweezers with back-focal-plane photodetection. The method combines power spectral measurements of thermal motion and the response to a sinusoidal motion of a translation stage. It consequently does not use the drag coefficient of the trapped object as an input. Thus, neither the viscosity, nor the size of the trapped object, nor its distance to nearby surfaces needs to be known. The method requires only a low level of instrumentation and can be applied in situ in all spatial dimensions. It is both accurate and precise: true values are returned, with small error bars. We tested this experimentally, near and far from surfaces in the lateral directions. Both position and force calibrations were accurate to within 3%. To calibrate, we moved the sample with a piezoelectric translation stage, but the laser beam could be moved instead, e.g., by acousto-optic deflectors. Near surfaces, this precision requires an improved formula for the hydrodynamical interaction between an infinite plane and a microsphere in nonconstant motion parallel to it. We give such a formula.

Tolic-Noerrelykke, Simon F.; Schaeffer, Erik; Howard, Jonathon; Pavone, Francesco S.; Juelicher, Frank; Flyvbjerg, Henrik [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, 01187 Dresden (Germany) and European Laboratory for Non-linear Spectroscopy, via Nello Carrara 1, 50019 Sesto Fiorentino, Florence (Italy) and Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden (Germany); European Laboratory for Non-linear Spectroscopy, via Nello Carrara 1, 50019 Sesto Fiorentino, Florence (Italy); Max Planck Institute for the Physics of Complex Systems, Noethnitzer Strasse 38, 01187 Dresden (Germany); Isaac Newton Institute for Mathematical Sciences, Cambridge CB3 0EH (United Kingdom); Biosystems Department, Risoe National Laboratory, DK-4000 Roskilde (Denmark) and Danish Polymer Centre, Risoe National Laboratory, DK-4000 Roskilde (Denmark)

2006-10-15

75

Multispectral Thermal Imager Optical Assembly Performance and Intergration of the Flight Focal Plane Assembly  

SciTech Connect

The Multispectral Thermal Imager Optical Assembly (OA) has been fabricated, assembled, successfully performance tested, and integrated into the flight payload structure with the flight Focal Plane Assembly (FPA) integrated and aligned to it. This represents a major milestone achieved towards completion of this earth observing E-O imaging sensor that is to be operated in low earth orbit. The OA consists of an off-axis three mirror anastigmatic (TMA) telescope with a 36 cm unobscured clear aperture, a wide-field-of-view (WFOV) of 1.82° along the direction of spacecraft motion and 1.38° across the direction of spacecraft motion. It also contains a comprehensive on-board radiometric calibration system. The OA is part of a multispectral pushbroom imaging sensor which employs a single mechanically cooled focal plane with 15 spectral bands covering a wavelength range from 0.45 to 10.7 µm. The OA achieves near diffraction-limited performance from visible to the long-wave infrared (LWIR) wavelengths. The two major design drivers for the OA are 80% enpixeled energy in the visible bands and radiometric stability. Enpixeled energy in the visible bands also drove the alignment of the FPA detectors to the OA image plane to a requirement of less than ± 20 µm over the entire visible detector field of view (FOV). Radiometric stability requirements mandated a cold Lyot stop for stray light rejection and thermal background reduction. The Lyot stop is part of the FPA assembly and acts as the aperture stop for the imaging system. The alignment of the Lyot stop to the OA drove the centering and to some extent the tilt alignment requirements of the FPA to the OA.

Blake, Dick; Byrd, Don; Christensen, Wynn; Henson, Tammy; Krumel, Les; Rappoport, William; Shen, Gon-Yen

1999-06-08

76

A hybrid active optical system for wave front preservation and variable focal distance  

NASA Astrophysics Data System (ADS)

A new Free Electron Laser (FEL) user facility, named FERMI@Elettra, is under construction at Sincrotrone Trieste (Italy). It is based on a seeded scheme to provide an almost perfect transform limited beam with fully spatial coherence. The wavelength range will be 100-3 nm with fundamental and will go down to 1 nm by using higher harmonics. It will be operative by autumn 2010. The exceptional characteristics of the source must be preserved until the experimental chamber, where a large set of different experiments will be performed. This condition poses very tight requirements to the design of the beamlines and, in particular, to the focusing optics. Here we will present the active optics system developed for Fermi but intended to be used also on the Elettra beamlines. It is based on the adoption of a hybrid active system composed by UHV compatible stepping motors and piezo ceramic actuators. These mirrors are supposed to provide focal distances from 0.8 m to infinity with an angle of incidence up to a few degrees and residual shape errors below 10 or 5 nm (depending on the wavelength). In this way it is possible to work with an almost perfect focused coherent beam as well as with a uniform defocused or unfocused image. The metrology results on the first 400 mm long mirror will be shown and the actuator system described. A strain gauge assembly, calibrated in Elettra by means of a long trace profiler, and controlled by a custom made electronic system developed by us, is used as a direct in situ encoder.

Cocco, Daniele; Bortoletto, Gianluca; Sergo, Rudi; Sostero, Giovanni; Cudin, Ivan

2010-05-01

77

Correlation of Choroidal Thickness and Volume Measurements with Axial Length and Age Using Swept Source Optical Coherence Tomography and Optical Low-Coherence Reflectometry  

PubMed Central

Purpose. To report choroidal thickness and volume in healthy eyes using swept source optical coherence tomography (SS-OCT). Methods. A prospective observational study of 122 patients examined with swept source OCT (DRI-OCT, Topcon, Japan). In each eye, we performed 256 horizontal scans, 12?mm in length and centered on the fovea. We calculated choroidal thickness manually with a built-in caliper and automatically using DRI-OCT mapping software. Choroidal volume was also automatically calculated. We measured axial length with optical low-coherence reflectometry (Lenstar LS 900, Haag-Streit, Switzerland). Results. The choroid has focally increased thickness under the fovea. Choroid was thinnest in the outer nasal quadrant. In stepwise regression analysis, age was estimated as the most significant factor correlating with decreased choroidal thickness (F = 23.146, P < 0.001) followed by axial length (F = 4.902, P = 0.03). Refractive error was not statistically significant (F = 1.16, P = 0.28). Conclusions. SS-OCT is the first commercially available system that can automatically create choroidal thickness and volume maps. Choroidal thickness is increased at the fovea and is thinnest nasally. Age and axial length are critical for the estimation of choroidal thickness and volume. Choroidal measurements derived from SS-OCT images have potential value for objectively documenting disease-related choroidal thickness abnormalities and monitoring progressive changes over time. PMID:25013793

Michalewski, Janusz; Nawrocka, Zofia; Bednarski, Maciej; Nawrocki, Jerzy

2014-01-01

78

Joint statistics of photon path length and cloud optical depth: Case studies  

Microsoft Academic Search

We show the joint statistics of photon path length and cloud optical depth for cloudy sky cases observed at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site between September and December 1997. The photon path lengths are retrieved from moderate resolution oxygen A-band observations taken by a rotating shadow band spectroradiometer (RSS). For high optical depth cloud cases,

Qilong Min; Lee C. Harrison; Eugene E. Clothiaux

2001-01-01

79

New optical modalities utilizing curved focal plane imaging detector devices and large arrays for terrestrial and spaceborne telescopes  

NASA Astrophysics Data System (ADS)

As terrestrial and spaceborne astronomical telescopes advance in multi-functional design sophistication, incorporating greater spectral resolutions, the utilization of curved focal plane ccd and cmos imaging detectors, contoured to match the telescope's Petzval field of curvature, provides a fundamental and novel optical simplicity facilitating new imaging frontiers in astronomical research. For space based telescopes, curved focal plane detector devices require significantly fewer optics than their flat counterparts, which require field flattening optics, in achieving maximum imaging resolutions for adjoining spectrometers or imaging cameras. consequently, with fewer optics comes greater room to place other optics within the same space to accomplish other tasks, providing much greater diversification of observing functions and techniques reserved simultaneously for the telescope. Included within this is the operational capability of producing multi-wavelength spectrometers gathering data concurrently at a multitude of selected wavelengths, with greater sensitivity, reliability, size reduction, and operational longevity of the restructured optical system. Specialized applications involving optical interferometry are also achievable with further enhancements when the curved detectors are applied specifically to refine or maximize detection of fringes, and when employing occulting mask algorithms for existing light paths. for planetary surface mapping space probes, curved focal plane detection provides real-time 3D multi-perspective image acquisition for streaming 3D data sets, replacing onboard or remote computationally intensive 3D reconstructions used for examining terrestrial surface features performed with corresponding flat detectors. For earth based telescopes, where mass of the telescope's optics are not so constrained, more degrees of freedom are also part of the benefits introduced by curved focal plane detector device optimization. Associated with the very large Petzval radii of curvature for very large and extreme telescopes within this class are wide field spatial distortions which are instantaneously corrected when arrays of curved CCD's or CMOS devices are joined homogeneously and precisely together along the converging field of curvature, without field flattening optics, insuring complete full field detection superior to flat facet detectors which compromise the telescope's imaging field curvature detection abilities.

Mark, David

2010-07-01

80

Influence of pump-wavelength and crystal length on the phase-matching of optical  

E-print Network

Influence of pump-wavelength and crystal length on the phase-matching of optical rectification Nick and the wavelength of the generating optical pulse are varied. The difference between the group-velocity at optical on the ter- ahertz frequency, the wavelength of the generating pulse and the thickness 3 #12;of

81

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

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

82

ADVANCES AND NEW TECHNIQUES IN LENGTH MEASUREMENTS BY OPTICAL INTERFEROMETRY  

Microsoft Academic Search

Studies of a long gauge block Kösters interferometer, performed at INMETRO, and the results of the CIPM Key Comparison CCL-2 show that the uncertainty in realization of the SI length unit achieved with this type of instrument in the range of 500 mm is ~1 part in 108. Basic advances in philosophy and techniques of high-precision temperature measurements, realized in

Alexandre Titov; Igor Malinovsky

83

A scalable optical packet switch for variable length packets employing shared electronic buffering  

Microsoft Academic Search

A scalable optical packet switch design handling variable length packets by employing shared electronic buffering is analysed. Contention resolution is done using the wavelength dimension and a minimum number of buffer inputs.

S. Bjomstad; D. R. Hjelme; N. Stol

2002-01-01

84

Focal lengths and gravity waves  

E-print Network

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 ...

Doherty, Mary Jane

1985-01-01

85

Generation of a sub-wavelength focal spot with a long transversally polarized optical needle using a double-ring-shaped azimuthally polarized beam  

NASA Astrophysics Data System (ADS)

Based on the vector diffraction theory, we study the tight focusing performance of a double-ring-shaped azimuthally polarized beam through a high numerical aperture objective using a spiral phase plate or a seven-belt complex filter modulated spiral phase hologram (SCF-SPH). The effect of truncation parameters on the tight focusing is demonstrated. The dependence of various polarizations on the intensity, focal shift and side lobe are also investigated. It is shown that the focal shift can be removed successfully and the side lobe can be reduced effectively by introducing a SCF-SPH into the imaging system. Also, a sub-wavelength focal spot along with a long transversally polarized optical needle is achieved. The polarization evolution of the wavefront near the focal plane is analyzed by calculating the Stokes polarization parameters. It is revealed that the annihilation of the polarization singularity at the beam center makes a bright focal spot possible.

Nie, Zhongquan; Li, Zhongguo; Shi, Guang; Zhang, Xueru; Wang, Yuxiao; Song, Yinglin

2014-08-01

86

Determination of spin diffusion length in Germanium by optical and electrical spin injection  

NASA Astrophysics Data System (ADS)

We report on the measurements of spin diffusion length and lifetime in Germanium with both magneto-electro-optical and magneto-electrical techniques. Magneto-electro-optical measurements were made by optically inject in Fe/MgO/Ge spin-photodiodes a spin polarized population around the ? point of the Brillouin zone of Ge at different photon energies. The spin diffusion length is obtained by fitting by a mathematical model the photon energy dependence of the spin signal, due to switching of the light polarization from left to right, leading to a spin diffusion length of 0.9±0.2 ?m at room temperature. Non-local four-terminals and Hanle measurements performed on Fe/MgO/Ge lateral devices, at room temperature, instead lead to 1.2±0.2 ?m. The compatibility of these values among the different measurement methods validates the use all of all of them to determine the spin diffusion length in semiconductors. While electrical methods are well known in semiconductor spintronics, in this work we demonstrate that the optical pumping versus photon energy is an alternative and reliable method for the determination of the spin diffusion length whereas the band structure of the semiconductor allows for a non-negligible optical spin orientation.

Rinaldi, Christian; Bertoli, Stefano; Cantoni, Matteo; Manzoni, Cristian; Marangoni, Marco; Cerullo, Giulio; Bianchi, Massimiliano; Sordan, Roman; Bertacco, Riccardo

2014-08-01

87

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

E-print Network

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...

Frick, Manuel

2014-01-01

88

Abstract -This paper proposes and analyzes a two-stage optical switch architecture supporting asynchronous variable length  

E-print Network

asynchronous variable length packet switching for optical label switching network applications. The proposed of the asynchronous switching of variable length packets for multiprotocol OLS networks. The scheduling scheme - Contention resolution, look-ahead scheduling, load balance, optical label switching, optical packet switching

Kolner, Brian H.

89

PLR analysis of optical packet switch with different packet length distribution  

NASA Astrophysics Data System (ADS)

The paper studies the performance of an all-optical packet switch (OPS) for different packet length. The packet loss ratio, considered the OPS without FDL and with FDL buffer, with different length distribution are analyzed under the Poisson arrival process and a burst super exponential arrival process respectively. The experiment and analysis show that the performance of different length packet is influence by the packet arrival process and the buffer size. When the OPS without buffer, the PLR under bursty traffic yields the higher packet loss ratio (PLR). PLR with Poisson arrival packet is not influenced by the packet length distribution, while with the super exponential traffic, the packet length distribution influences the PLR, and the fixed length packet yields higher PLR compared to the variable length exponential packet and the experiential Internet traffic. When the OPS with buffer, PLR with Poisson arrival packet yields lower than with super exponential packet under the same load, and the experiential length super exponential packet leads to highest PLR, while the fixed length Poisson process packet brings on lowest PLR.

Liu, Huanlin; Chen, Qianbin; Pan, Yingjun

2006-09-01

90

Terahertz emission induced by optical beating in nanometer-length field-effect transistors  

E-print Network

Terahertz emission induced by optical beating in nanometer-length field- effect transistors PN/AlGaN/GaN metal-insulator-semiconductor heterostructure field-effect transistors AIP Advances 2, 022134 (2012) Ultra-low resistance ohmic contacts in graphene field effect transistors Appl. Phys. Lett. 100, 203512

Paris-Sud XI, Université de

91

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

Microsoft Academic Search

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

SHIGEKI SAKAGUCHI

1984-01-01

92

Asymptotic expressions for calculation of length of decay of linear-polarized groups in optical fibers  

NASA Astrophysics Data System (ADS)

The asymptotic expressions for the difference of axial propagation constants of waveguide modes inside one linear-polarized modal group and length of decay of polarization in step index profile optical fibers are submitted. The estimation of accuracy of the obtained formulas is executed.

Kiesewetter, Dmitry

2005-02-01

93

Temporal characterization of FEL micropulses as function of cavity length detuning using frequency-resolved optical gating  

SciTech Connect

Results of frequency resolved optical gating (FROG) measurements on the Stanford mid-IR FEL system show the effect of FEL cavity length detuning on the micropulse temporal structure. The FROG technique enables the acquisition of complete and uniquely invertible amplitude and phase temporal dependence of optical pulses. Unambiguous phase and amplitude profiles are recovered from the data. The optical pulses are nearly transform limited, and the pulse length increases with cavity length detuning.

Richman, B.A. [Stanford Univ., CA (United States); DeLong, K.W.; Trebino, R. [Sandia National Lab., Livermore, CA (United States)

1995-12-31

94

Second harmonic generation in optical fibers. Experimental study of the self-organised holographic grating length  

NASA Astrophysics Data System (ADS)

We report experimental results concerning self-organised holographic grating length for second harmonic generation in optical fiber. By a cut-back method of the fiber and a comparison between different laser regimes we point out the limiting factors to its extension. The grating length is found to be independent of the pulse duration. We have established experimental evidence of the limitation of the grating length by self- and cross-phase modulations effects, spectral width of the pulses and central frequency fluctuation of the laser. With a stable Nd:YAG injected laser delivering transform-limited pulses we obtain for the first time to our knowledge, holographic grating lengths above 60 cm.

Demouchy, G.

1993-09-01

95

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

PubMed

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

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

2012-06-01

96

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

PubMed

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

Gao, Qiong; Jiang, Zongfu; Yi, Shihe

2014-06-01

97

Optical biopsy of breast tissue using differential path-length spectroscopy  

NASA Astrophysics Data System (ADS)

Differential path-length spectroscopy (DPS) was used to determine the local optical properties of breast tissue in vivo. DPS measurements were made on healthy and malignant breast tissue using a fibre-optic needle probe, and were correlated to the histological outcome of core-needle biopsies taken from the same location as the measurements. DPS yields information on the local tissue blood content, the local blood oxygenation, the average micro-vessel diameter, the ?-carotene concentration and the scatter slope. Our data show that malignant breast tissue is characterized by a significant decrease in tissue oxygenation and a higher blood content compared to normal breast tissue.

van Veen, Robert L. P.; Amelink, Arjen; Menke-Pluymers, Marian; van der Pol, Carmen; Sterenborg, Henricus J. C. M.

2005-06-01

98

Experimental validation of optimization concepts for focal-plane image processing with adaptive optics  

NASA Astrophysics Data System (ADS)

We show experimental results demonstrating the feasibility of an extremely fast sequential phase-diversity (SPD) algorithm for point sources. The algorithm can be implemented on a typical adaptive optics (AO) system to improve the wavefront reconstruction beyond the capabilities of a wavefront sensor by using the information from the imaging camera. The algorithm is based on a small-phase approximation enabling fast numerical implementation, and it finds the optimal wavefront correction by iteratively updating the deformable mirror. Our experiments were made at an AO-setup with a 37 actuator membrane mirror, and the results show that the algorithm finds an optimal image quality in 5-10 iterations, when the initial wavefront errors are typical non-common path aberrations having a magnitude of 1-1.5 rad rms. The results are in excellent agreement with corresponding numerical simulations.

Korkiakoski, Visa; Keller, Christoph U.; Doelman, Niek; Fraanje, Rufus; Andrei, Raluca; Verhaegen, Michel

2012-07-01

99

arXiv:physics/0511072v2[physics.optics]14Apr2006 Optical fibers with interferometric path length stability by controlled heating for  

E-print Network

path length of an optical fiber to an accuracy of about 1/100 of the laser wavelength. We study the dynamic response of the path length to modulation of an electrically conductive heater layer of the fiber. The path length is measured against the laser wavelength by use of the Pound-Drever-Hall method; negative

Peters, Achim

100

Changes in diffusion path length with old age in diffuse optical tomography  

NASA Astrophysics Data System (ADS)

Diffuse, optical near infrared imaging is increasingly being used in various neurocognitive contexts where changes in optical signals are interpreted through activation maps. Statistical population comparison of different age or clinical groups rely on the relative homogeneous distribution of measurements across subjects in order to infer changes in brain function. In the context of an increasing use of diffuse optical imaging with older adult populations, changes in tissue properties and anatomy with age adds additional confounds. Few studies investigated these changes with age. Duncan et al. measured the so-called diffusion path length factor (DPF) in a large population but did not explore beyond the age of 51 after which physiological and anatomical changes are expected to occur [Pediatr. Res. 39(5), 889-894 (1996)]. With increasing interest in studying the geriatric population with optical imaging, we studied changes in tissue properties in young and old subjects using both magnetic resonance imaging (MRI)-guided Monte-Carlo simulations and time-domain diffuse optical imaging. Our results, measured in the frontal cortex, show changes in DPF that are smaller than previously measured by Duncan et al. in a younger population. The origin of these changes are studied using simulations and experimental measures.

Bonnéry, Clément; Leclerc, Paul-Olivier; Desjardins, Michèle; Hoge, Rick; Bherer, Louis; Pouliot, Philippe; Lesage, Frédéric

2012-05-01

101

Integrating sphere effective optical path length calibration by gas absorption spectroscopy  

NASA Astrophysics Data System (ADS)

A method of integrating sphere effective optical path length (EOPL) evaluation using tunable diode laser absorption spectroscopy for gas detection was demonstrated. Oxygen was used as a sample gas for an 8.38 cm diameter integrating sphere calibration; 393.7 ± 1.3 cm EOPL was obtained from the wavelength modulation spectroscopy with second harmonic calibration by measuring oxygen P11 line at 764 nm, which is in agreement with that of 393 cm by using direct absorption spectroscopy calibration. The EOPL calibration accuracy of this method can reach 0.33 %. It has been justified that the EOPL of an integrating sphere is independent of the incident light intensity.

Gao, Qiang; Zhang, Yungang; Yu, Jia; Zhang, Zhiguo; Wu, Shaohua; Guo, Wei

2014-03-01

102

Optical path-length modulation for three-dimensional particle measurement in mirror-embedded microchannels.  

PubMed

Simple and low-cost implementation of three-dimensional (3D) particle measurement is vital for designing and characterizing microfluidic devices that show spatiotemporally varying characteristics in three dimensions. However, the conventional 3D particle image velocimetry or particle streak velocimetry has proven difficult to address the needs, requiring complex and expensive equipment, precise alignment between optical components, and specialized image-processing algorithms. Here, we report mirror-embedded microchannels and a method of optical path-length (OPL) modulation for 3D particle measurement in the channels. The mirror, ideally at 45 degrees, reflects the side view of the channels and enables 3D positional information to be obtained easily from two different orthogonal-axis images with different optical paths. To offset the optical path difference between two image views, we utilized a cover glass as a medium of high refractive index and placed it in the light path through which the side-view image propagates, thereby prolonging the OPL of the side view and simultaneously shifting its depth of field (DOF) range. This modulation ensures imaging of in-focus side view as well as top view. This 3D imaging principle was verified by observing 3D positions of 6 mum-sized beads in the linear and grooved microchannels. The mirror-embedded scheme can be readily fabricated with existing microfluidic designs, and offer easy and simple implementation of 3D particle measurement. PMID:20091005

Choi, Sungyoung; Kim, Seung-Hoon; Park, Je-Kyun

2010-02-01

103

Morphometric analysis of small arteries in the human retina using adaptive optics imaging: relationship with blood pressure and focal vascular changes  

PubMed Central

Objectives: The wall-to-lumen ratio (WLR) of retinal arteries is a recognized surrogate of end-organ damage due to aging and/or arterial hypertension. However, parietal morphometry remains difficult to assess in vivo. Recently, it was shown that adaptive optics retinal imaging can resolve parietal structures of retinal arterioles in humans in vivo. Here, using adaptive optics retinal imaging, we investigated the variations of parietal thickness of small retinal arteries with blood pressure and focal vascular damage. Methods: Adaptive optics imaging of the superotemporal retinal artery was done in 49 treatment-naive individuals [mean age (±SD) 44.9 years (±14); mean systolic pressure 132?mmHg (±22)]. Semi-automated segmentation allowed extracting parietal thickness and lumen diameter. In a distinct cohort, adaptive optics images of arteriovenous nicking (AVN; n?=?12) and focal arteriolar narrowing (FAN; n?=?10) were also analyzed qualitatively and quantitatively. Results: In the cohort of treatment-naive individuals, by multiple regression taking into account age, body mass index, mean, systolic, diastolic and pulse blood pressure, the WLR was found positively correlated to mean blood pressure and age which in combination accounted for 43% of the variability of WLR. In the cohort of patients with focal vascular damage, neither FANs or AVNs showed evidence of parietal growth; instead, at sites of FANs, decreased outer diameter suggestive of vasoconstriction was consistently found, while at sites of AVNs venous narrowing could be seen in the absence of arteriovenous contact. Conclusion: High resolution imaging of retinal vessels by adaptive optics allows quantitative microvascular phenotyping, which may contribute to a better understanding and management of hypertensive retinopathy. PMID:24406779

Koch, Edouard; Rosenbaum, David; Brolly, Aurelie; Sahel, Jose-Alain; Chaumet-Riffaud, Philippe; Girerd, Xavier; Rossant, Florence; Paques, Michel

2014-01-01

104

Multiplexing of Long-Length Fiber Bragg Grating Distributed Sensors Based on Synthesis of Optical Coherence Function  

Microsoft Academic Search

Long-length fiber Bragg grating (FBG) distributed sensors are multiplexed, and measurement of Bragg wavelength distribution along the gratings are demonstrated. This sensing system adopts synthesis of optical coherence function (SOCF) as ar eflectometry technique to measure the distribution of the local reflection spectra inside the long-length FBGs. Simulations have been carried out to determine appropriate FBG reflectivity for the multiplexing.

Koji Kajiwara; Kazuo Hotate

2011-01-01

105

Scintillators For Fiber Optics: System Sensitivity And Bandwidth As A Function Of Fiber Length  

NASA Astrophysics Data System (ADS)

Scintillators have been employed for several years as ionizing radiation-to-light converters in plasma diagnostic experiments that utilize fiber optics. Until recently, nano-second and subnanosecond scintillators were available only in the near ultraviolet.1 However, the bandwidth and transmission properties of fiber optics both strongly favor operation at longer wavelengths. More recently, nanosecond and subnanosecond scintillators with emission peaks around 480 nm have been reported.2 A time-resolved plasma-imaging experiment using one of these scintillators and 100 channels of graded-index fiber, each 500 m long, has been successfully tested on a nuclear event at the Nevada Test Site. During the past year we have developed several new scintillator systems with emission wavelengths more compatible with fiber optics and with response times in the nanosecond andsubnanosecond time region. One scintillator, based on Kodak dye 14567 (DCM), has an emission maximum at 650 nm and a response time (FWHM) of 1.2 ns. Experimental data on system sensitivity and bandwidth versus fiber length are presented for three fluor-fiber systems. Data on fluor formulation, response time, and linearity-of-response are given, and a model for scintillator nonlinearity, based on solvent, radiation-induced, transient absorption, is presented.

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

1982-01-01

106

Influence of the word length and input power on nonlinear crosstalk induced by hybrid optical amplifiers  

NASA Astrophysics Data System (ADS)

In this paper, the influence of the word length (WL) of a pseudo-random bit sequence (PRBS) and the input laser power on nonlinear crosstalk induced by the different hybrid optical amplifiers (HOAs) has been examined. It is found that the crosstalk is strongly dependent on the WL and very sensitive to the relative powers of the input signals at 0.2 nm and 0.4 nm of the channel spacing. It is shown that the proposed hybrid Raman-EDFA induces lesser crosstalk as compared to other HOAs. The performance of Raman-EDFA HOA is also investigated for 16 × 10 Gbps dense wavelength division multiplexed (DWDM) system at 0.2 nm of channel spacing.

Singh, Simranjit; Kaler, R. S.

2013-10-01

107

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

NASA Astrophysics Data System (ADS)

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.

Biaggio, Ivan; Coda, Virginie; Montemezzani, Germano

2014-10-01

108

Surfactant-triggered disassembly of electrostatic complexes probed at optical and quartz crystal microbalance length scales.  

PubMed

A critical advantage of electrostatic assemblies over covalent and crystalline bound materials is that associated structures can be disassembled into their original constituents. Nanoscale devices designed for the controlled release of functional molecules already exploit this property. To bring some insight into the mechanisms of disassembly and release, we study the disruption of molecular electrostatics-based interactions via competitive binding with ionic surfactants. To this aim, free-standing micrometer-size wires were synthesized using oppositely charged poly(diallyldimethylammonium chloride) and poly(acrylic acid) coated iron oxide nanoparticles. The disassembly is induced by the addition of sodium dodecyl sulfates that complex preferentially the positive polymers. The process is investigated at two different length scales: the length scale of the particles (10 nm) through the quartz crystal microbalance technique and that of the wires (>1 ?m) via optical microscopy. Upon surfactant addition, the disassembly is initiated at the surface of the wires by the release of nanoparticles and by the swelling of the structure. In a second step, erosion involving larger pieces takes over and culminates in the complete dissolution of the wires, confirming the hypothesis of a surface-type swelling and erosion process. PMID:24773519

Schonbeck, N; Kvale, K; Demarcy, T; Giermanska, J; Chapel, J-P; Berret, J-F

2014-05-20

109

Optical stability testing of the fiber support technology (FiST) focal plane assembly of the SABER instrument  

Microsoft Academic Search

The focal plane assembly of the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument is supported using Fiber Support Technology (FiST) which utilizes high performance fibers in tension to mechanically support and thermally isolate a cooled component from a warm environment. Details of this approach were presented in detail at SPIE meeting in Denver in 1996. The SABER

Scott M. Jensen; J. Clair Batty; Roy W. Esplin; Matthew J. Felt

1998-01-01

110

Optical fibers with interferometric path length stability by controlled heating for transmission of optical signals and as components in frequency standards  

E-print Network

We present a simple method to stabilize the optical path length of an optical fiber to an accuracy of about 1/100 of the laser wavelength. We study the dynamic response of the path length to modulation of an electrically conductive heater layer of the fiber. The path length is measured against the laser wavelength by use of the Pound-Drever-Hall method; negative feedback is applied via the heater. We apply the method in the context of a cryogenic resonator frequency standard.

Müller, H; Peters, A; Braxmaier, Claus; Mueller, Holger; Peters, Achim

2006-01-01

111

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)

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.

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

2009-01-01

112

Performance of embedded short-gage-length optical fiber sensors in a fatigue-loaded reinforced concrete specimen  

Microsoft Academic Search

This paper reports the performance of short-gage-length optical fiber sensors embedded in a reinforced concrete specimen. Embedded extrinsic Fabry-Perot optical fiber sensors, attached to steel reinforcement rods, were used to monitor local displacements and strain in a concrete cross-beam specimen. The strain data obtained from the fiber sensors were compared with data obtained from collocated foil strain gages. Absolute extrinsic

M. Devries; M. Nasta; V. Bhatia; T. Tran; J. Greene; R. O. Claus; S. Masri

1995-01-01

113

OPTICAL SYSTEMS: Calculation of the illuminance distribution in the focal spot of a focusing system taking into account aberrations in this system and divergence of a focused laser beam  

NASA Astrophysics Data System (ADS)

The dependence of the focal-spot size of a 'deep' parabolic mirror reflector on the laser-beam divergence is analysed by the method of elementary reflections. The dependence of the focal-beam diameter of an ideal focusing optical system on the laser-beam parameters is described. The expression is obtained for calculating the illumination distribution in the focal spot of a 'deep' mirror reflector which takes into account both aberrations and light-gathering power of the reflector and the divergence of a focused laser beam.

Gitin, Andrey V.

2007-03-01

114

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

Microsoft Academic Search

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.

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

1986-01-01

115

Focal spot analysis of optical inhomogeneities appearing in the working medium of an iodine photodissociation laser with flashlamp pumping  

NASA Astrophysics Data System (ADS)

We report on the results of experimental studies of optical inhomogeneities appearing in the working medium of an iodine photodissociation laser operating in the inversion accumulation mode and in the free-running mode. The dynamics of evolution of optical inhomogeneities in the free-running mode is studied experimentally.

Kachalin, G. N.; Pivkin, D. N.; Polozov, A. A.; Safronov, A. S.; Khudikov, N. M.

2013-01-01

116

[Influence of optical path length on NIR analysis results for trace metal determination in Chinese rice wine].  

PubMed

The prediction performance of near infrared (NIR) spectra with different optical path-length for trace metal (potassium, calcium, magnesium, zincum, and iron) determination was investigated. NIR transmission spectra of Chinese rice wine were collected in rectangular quartz cuvette with different optical path lengths (1, 2, 5 and 10 mm) using Fourier transform near infrared (FT-NIR) spectrometer in the wavelength range of 800-2 500 nm with air as the reference. The reference data for potassium, calcium, magnesium, zinc, and iron were determined by atomic absorption spectroscopy (AAS). Calibration models were developed by partial least squares (PLS) regression. The PLS models of NIR spectra group with 5 mm path length gave the best calibration result. The determination coefficients (r2) for potassium, calcium, magnesium, zincum, and iron were 0.93, 0.85, 0.93, 0.72, and 0.66, respectively, and the root mean square error of cross validation (RMSECV) for the five elements were 26.5, 35.6, 4.63, 0.26, and 0.64 mg x L-(-1), respectively, whereas the models established by NIR spectra group of 10 mm path-length was the worst. And the r2 values for potassium, calcium, magnesium, zincum, and iron were 0.61, 0.65, 0.63, 0.09, and 0.25, respectively. The results indicated that the optical path length has an influence on the NIR analysis results for trace metal determination in Chinese rice wine, and that the appropriate path length for the NIR analysis should be determined by comparison analysis. PMID:17763771

Yu, Hai-Yan; Ying, Yi-Bin; Xie, Li-Juan; Fu, Xia-Ping

2007-06-01

117

Compact color schlieren optical system  

NASA Astrophysics Data System (ADS)

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.

Buchele, Donald R.; Griffin, Devon W.

1993-08-01

118

Compact color schlieren optical system  

NASA Technical Reports Server (NTRS)

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.

Buchele, Donald R.; Griffin, Devon W.

1993-01-01

119

Compact color schlieren optical system  

Microsoft Academic Search

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

Donald R. Buchele; Devon W. Griffin

1993-01-01

120

Electro-optic KTN Devices  

NASA Astrophysics Data System (ADS)

We have grown KTN crystals with optical quality, and developed high-speed beam deflectors and variable focal length lenses based on KTN's large electro-optic effect. Furthermore, by using the KTN beam deflectors, we have developed a swept light source for OCT operable at 200 kHz.

Yagi, Shogo; Fujiura, Kazuo

121

Experimental study of a fiber optical gyro utilizing a ring resonator and a low-coherence length light source  

NASA Astrophysics Data System (ADS)

A re-entrant fiber optic gyro (RE-FOG) that utilizes a ring resonator (RR) and a low-coherence length light source is designed and demonstrated. A reflector is placed on one end of input/output directional coupler to realize light beams propagating in CW and CCW directions. RE-FOG promises a higher sensitivity than the conventional Sagnac interferometer fiber optic gyro (I-FOG) without the disadvantages of a resonant fiber optic gyro (R-FOG). Theoretical considerations of the sensitivity and the resolution of RE-FOG are discussed. Experimental results (the constant bias of 0.2 deg/h and the variance of random drift rate better than 0.1 deg/h) are also presented.

Hu, Zhaoyang; Ma, Xinyu; Li, Fuying; Tang, Quan'an; Zhou, Shiqin; Wu, Yanji

1999-12-01

122

Full-length axon regeneration in the adult mouse optic nerve and partial recovery of simple visual behaviors.  

PubMed

The mature optic nerve cannot regenerate when injured, leaving victims of traumatic nerve damage or diseases such as glaucoma with irreversible visual losses. Recent studies have identified ways to stimulate retinal ganglion cells to regenerate axons part-way through the optic nerve, but it remains unknown whether mature axons can reenter the brain, navigate to appropriate target areas, or restore vision. We show here that with adequate stimulation, retinal ganglion cells are able to regenerate axons the full length of the visual pathway and on into the lateral geniculate nucleus, superior colliculus, and other visual centers. Regeneration partially restores the optomotor response, depth perception, and circadian photoentrainment, demonstrating the feasibility of reconstructing central circuitry for vision after optic nerve damage in mature mammals. PMID:22615390

de Lima, Silmara; Koriyama, Yoshiki; Kurimoto, Takuji; Oliveira, Julia Teixeira; Yin, Yuqin; Li, Yiqing; Gilbert, Hui-Ya; Fagiolini, Michela; Martinez, Ana Maria Blanco; Benowitz, Larry

2012-06-01

123

Measurement of Optical Path Length for Cerebral Near-Infrared Spectroscopy in Newborn Infants  

Microsoft Academic Search

The time taken for an extremely short pulse of near-infrared laser light to traverse the heads of 6 preterm infants was measured after death. The values obtained were used to calculate a differential path length factor (DPF), defined as the mean distance travelled by the photons divided by the distance between the points where light entered and left the head.

J. S. Wyatt; M. Cope; D. T. Delpy; P. van der Zee; S. R. Arridge; A. D. Edwards; E. O. R. Reynolds

1990-01-01

124

Design of an Airborne Scanning Lidar Using a Holographic Optical Element  

NASA Technical Reports Server (NTRS)

An aerosol and cloud backscatter lidar system has been built using a one meter focal length transmission holographic optical element that functions as a scanning telescope. Rotating the disk about the center line normal effects a 45 degree conical scan.

Schwemmer, Geary K.; Hopf, Dan; Neuman, Mark; Kubalak, David; Christhilif, Ellen; Hasselbrack, William; Ranganayakamma, Belthur; Kim, Jin; Hwang, I. H.

1998-01-01

125

Focal Reducer for CQUEAN (Camera for QUasars in EArly uNiverse)  

NASA Astrophysics Data System (ADS)

A focal reducer is developed for CQUEAN (Camera for QUasars in EArly uNiverse), which is a CCD imaging system on the 2.1 m Otto Struve telescope at the McDonald observatory. It allows CQUEAN to secure a wider field of view by reducing the effective focal length by a factor of three. The optical point spread function without seeing effects is designed to be within one pixel (0.283 arcsec) over the field of view of 4.82 arcmin × 4.82 arcmin in optimum wavelength ranges of 0.8-1.1 ?m. In this paper, we describe and discuss the characteristics of optical design, the lens and barrel fabrications and the alignment processes.The observation results show that the image quality of the focal reducer confirms the expectations from the design.

Lim, Juhee; Chang, Seunghyuk; Pak, Soojong; Kim, Youngju; Park, Won-Kee; Im, Myungshin

2013-08-01

126

Connection guidence and wave length assignment of optical systems using an intelligent control plane  

Microsoft Academic Search

In this work, the risks that optical systems face have been told. Then, it has been told that the proper solution to these risks is using intelligent control planes. After pointing the advantages, execution advancements and the property of reducing the costs; the standards produced to help different vendors to work together have been told. Then, how an intelligent control

K. Karayahsi; Arif Dolma; E. Ates; Nilay Çatal

2009-01-01

127

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

Microsoft Academic Search

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.

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

2010-01-01

128

Simultaneous measurement of the root-mean-square roughness and autocorrelation length by optical method  

Microsoft Academic Search

We developed an on-line measurement system for the simultaneous measurement of the root-mean-square roughness and autocorrelation length which are the parameters of surface roughness. The measurement is based on the scattering theory of light on the rough surface. Computer simulation shows that the measurement range depends on the wavelength of the light source, and this is verified with the experiment.

Dalwoo Kim; Ki-Jang Oh; Choong-Soo Lim

1998-01-01

129

Performance of Run-Length-Limited (3, 11) Code for Optical Storage  

NASA Astrophysics Data System (ADS)

This paper introduces a run-length-limited (RLL) (3, 11) code and compares its performance with that of the EFMPlus code using four different detection methods including partial response maximum likelihood (PRML), fixed delay tree search with decision feedback (FDTS/DF), partial response with decision feedback equalizer (PR-DFE) and decision feedback equalizer (DFE). The advantages of the proposed code are: (1) the larger density ratio and (2) the simple encoder/decoder.

Lee, Jun; Kim, Jaehyung; Yong, Sehyung; Lee, Jaejin

2001-03-01

130

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

PubMed Central

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

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

2012-01-01

131

Unilateral Isolated Proximal Femoral Focal Deficiency  

PubMed Central

Objective. To discuss a patient with a prenatal diagnosis of unilateral isolated femoral focal deficiency. Case. Antenatal diagnosis of unilateral isolated femoral focal deficiency was made at 20 weeks of gestation. The length of left femur was shorter than the right, and fetal femur length was below the fifth percentile. Proximal femoral focal deficiency was diagnosed. After delivery, the diagnosis was confirmed with skeletal radiographs and magnetic resonance imaging. In prenatal ultrasonographic examination, the early recognition and exclusion of skeletal dysplasias is important; moreover, treatment plans should be initiated, and valuable information should be provided to the family. PMID:23984135

Do?er, Emek; Köpük, ?ule Y.; Çak?ro?lu, Yi?it; Çak?r, Özgür; Yücesoy, Gülseren

2013-01-01

132

Eavesdropping in chaotic optical communication using the feedback length of an external-cavity laser as a key.  

PubMed

An external-cavity laser (ECL) operating in a chaotic state is usually used in a chaotic optical secure communication system and its feedback length (FL) is often regarded as an additional key. Our analyses show that an eavesdropper's (Eve) laser can synchronize with a transmitter (Alice) without any knowledge of the FL by simply increasing the injection strength. A sequence of a 1 Gbit/s nonreturn-to-zero message encoded by the FL as the key is successfully eavesdropped. The reason for the synchronization deviation between Alice's and Eve's lasers is given. Our results indicate that the FL as a key cannot enhance the security of chaotic optical communication using long-ECLs. PMID:19543362

Zhao, Qingchun; Wang, Yuncai; Wang, Anbang

2009-06-20

133

Length control of an optical resonator using second-order transverse modes  

E-print Network

We present the analysis of an unorthodox technique for locking a laser to a resonant optical cavity. Error signals are derived from the interference between the fundamental cavity mode and higher-order spatial modes of order two excited by mode mismatch. This scheme is simple, inexpensive and, in contrast to similar techniques, first-order-insensitive to beam jitter. After mitigating sources of technical noise, performance is fundamentally limited by quantum shot-noise.

Miller, John

2014-01-01

134

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

SciTech Connect

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.

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

1999-05-17

135

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

PubMed

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

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

2014-03-25

136

Path-length-resolved diffusive particle dynamics in spectral-domain optical coherence tomography.  

PubMed

We describe a new method to measure the decorrelation rate of the optical coherence tomography (OCT) magnitude simultaneously in space and time. We measure the decorrelation rate of the OCT magnitude in a Fourier-domain OCT system for a large range of translational diffusion coefficients by varying the sphere diameter. The described method uses the sensitivity advantage of Fourier-domain OCT over time-domain OCT to increase the particle diffusion imaging speed by a factor of 200. By coherent gating, we reduce the contribution of multiple scattering to the detected signal, allowing a quantitative study of diffusive particle dynamics in high concentration samples. We demonstrate that this technique is well suited to image diffusive particle dynamics in samples with a complex geometry as we measure the morphology and diffusive particle dynamics simultaneously with both high spatial and high temporal resolution. PMID:21231201

Kalkman, J; Sprik, R; van Leeuwen, T G

2010-11-01

137

Longitudinally polarized electric and magnetic optical nano-needles of ultra high lengths  

NASA Astrophysics Data System (ADS)

We demonstrate a method to generate longitudinally polarized electric and magnetic light spots over ultra-long distances. The method proposed here relies on the generation of radially and azimuthally polarized Bessel beams at the limit between propagating and evanescent regimes, by projecting radially and azimuthally polarized doughnut beams onto an axicon-based system of numerical aperture (NA) equal to 1. Tight electric and magnetic light spots (0.36?) can be produced over distances reaching 50? and with longitudinal intensities about 3.5×104 times above the transverse intensities. Same confinement abilities over distances larger than 335 ? is also predicted with longitudinal intensities 883 fold above the transverse ones. Experimental characterization of these tiny optical needles with polarization-resolved heterodyne SNOM reveals electric and magnetic light spots smaller than 0.4 ? whose longitudinal intensities are about 200-fold larger than the transverse ones.

Grosjean, T.; Gauthier, I.

2013-05-01

138

MIPAS focal-plane optics  

Microsoft Academic Search

The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) has been selected by ESA for the ENVISAT-Mission, scheduled for launch in 1998. The instrument will measure the concentration of a number of atmospheric trace gases in the earth atmosphere in a spectral region from 4.15 - 14.6 micrometers . Within this region measurements are performed with high spectral resolution. The MIPAS

Henk Bokhove; C. Smorenburg; H. Visser

1993-01-01

139

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)

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.

1976-01-01

140

Vergence, Vision, and Geometric Optics  

ERIC Educational Resources Information Center

Provides a definition of vergence in terms of the curvature of the wave fronts, and gives examples to illustrate the advantages of this approach. The vergence treatment of geometrical optics provides both conceptual and algebraic advantages, particularly for the life science student, over the traditional object distance-image distance-focal length…

Keating, Michael P.

1975-01-01

141

JSim: Simulating the JMAPS Focal Plane  

Microsoft Academic Search

Developed to support requirements development for the JMAPS (Joint Milli-Arcsecond Pathfinder Survey) mission, JSim is a Python-based focal plane simulator designed to incorporate effects which will affect the astrometric, photometric, and spectroscopic capabilities of the JMAPS satellite. It incorporates noise characteristics, variable point-spread functions, satellite vibrations, and variability in overall satellite parameters such as focal length and detector orientation. In

Daniel Veillette

2010-01-01

142

Direct optical switching of bistable cholesteric textures in chiral azobenzene-doped liquid crystals.  

PubMed

The direct optical switching of bistable cholesteric textures (i.e., planar and focal conic textures) in chiral azobenzene-doped liquid crystals (LCs) is demonstrated. Chiral azobenzene is a chiral dopant with optically tuned helical twisting power that results from the photo-isomerization between trans- and cis- isomers via exposure to UV or visible light. The pitch length of the material can be optically and repeatedly elongated and shortened. With regard to free energy, LCs tend to be stable at planar (focal conic) textures when pitch length is elongated (shortened) by exposure to UV (visible) light. Thus, direct optical switchable LC displays are investigated. PMID:24104076

Fuh, Andy Ying-Guey; Wu, Zong-Han; Cheng, Ko-Ting; Liu, Cheng-Kai; Chen, Yuan-Di

2013-09-23

143

A novel large scale focal plane telescope using focal plane pointing method  

NASA Astrophysics Data System (ADS)

Large scale focal plane are required by a telescope due to wide field of view with high resolution. Since the detector technology could not accomplish the challenge requirement we developed a focal plane pointing method. This method consists of a pointing mirror and four array detectors. The pointing mirror is placed between the optics and focal plane. As the mirror turns around the optical axis, the light from optics will be reflected to different direction where detector array is placed in the position of focal plane. The key techniques of this method are the pointing accuracy and stability of the pointing mirror and the flatness of the mosaic detector array. Our preliminary experiments indicate that this method is an effective and feasible way to get a large field of view and high resolution image.

Lin, Jianchun; Sun, Liwei; Yong, Chaoliang; Yang, Lin; Chen, Fansheng

144

Compact color schlieren optical system.  

PubMed

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. PMID:20830072

Buchele, D R; Griffin, D W

1993-08-01

145

The Noninvasive Measurement of Absolute Cerebral Deoxyhemoglobin Concentration and Mean Optical Path Length in the Neonatal Brain by Second Derivative Near Infrared Spectroscopy (Regular Articles)  

Microsoft Academic Search

We have used second differential near infrared spectroscopy of water to determine the mean optical path length of the neonatal brain. By obtaining the ratio of the second differential features of deoxyhemoglobin to those of water, the absolute cerebral concentration of deoxyhemoglobin can be monitored continuously and noninvasively. Nineteen neonates were studied; the gestational age at birth varied from 23

S. J. MATCHER; Chris Cooper; Hamamatsu Photonics

146

Effect of conjugation length on nonlinear optical parameters of anthraquinone dyes investigated using He-Ne laser operating in CW mode  

NASA Astrophysics Data System (ADS)

We report the studies on third-order optical nonlinearity and optical limiting of anthraquinone dyes. Z-scan technique was employed to evaluate the nonlinear parameters such as nonlinear absorption coefficient ?eff and nonlinear index of refraction n2. Continuous wave He-Ne laser was used as the source of excitation. The estimated values of ?eff, n2 and ?(3) are of the order of 10-3 cm/W, 10-5 esu and 10-7 esu respectively. The presence of donor and acceptor groups in the structure results in increase in conjugation length. This resulted in the enhancement of nonlinear optical parameters values of the dye. Multiple diffraction rings were observed when the samples were exposed to laser beam due to thermal lensing. Dyes exhibited good optical limiting behavior under the experimental conditions. The results indicate that the dyes investigated here are materialise as candidates for photonics device applications such as optical power limiters.

Pramodini, S.; Poornesh, P.

2014-10-01

147

Focal Contacts as Mechanosensors  

PubMed Central

The transition of cell–matrix adhesions from the initial punctate focal complexes into the mature elongated form, known as focal contacts, requires GTPase Rho activity. In particular, activation of myosin II–driven contractility by a Rho target known as Rho-associated kinase (ROCK) was shown to be essential for focal contact formation. To dissect the mechanism of Rho-dependent induction of focal contacts and to elucidate the role of cell contractility, we applied mechanical force to vinculin-containing dot-like adhesions at the cell edge using a micropipette. Local centripetal pulling led to local assembly and elongation of these structures and to their development into streak-like focal contacts, as revealed by the dynamics of green fluorescent protein–tagged vinculin or paxillin and interference reflection microscopy. Inhibition of Rho activity by C3 transferase suppressed this force-induced focal contact formation. However, constitutively active mutants of another Rho target, the formin homology protein mDia1 (Watanabe, N., T. Kato, A. Fujita, T. Ishizaki, and S. Narumiya. 1999. Nat. Cell Biol. 1:136–143), were sufficient to restore force-induced focal contact formation in C3 transferase-treated cells. Force-induced formation of the focal contacts still occurred in cells subjected to myosin II and ROCK inhibition. Thus, as long as mDia1 is active, external tension force bypasses the requirement for ROCK-mediated myosin II contractility in the induction of focal contacts. Our experiments show that integrin-containing focal complexes behave as individual mechanosensors exhibiting directional assembly in response to local force. PMID:11402062

Riveline, Daniel; Zamir, Eli; Balaban, Nathalie Q.; Schwarz, Ulrich S.; Ishizaki, Toshimasa; Narumiya, Shuh; Kam, Zvi; Geiger, Benjamin; Bershadsky, Alexander D.

2001-01-01

148

New method of estimating wavelength-dependent optical path length ratios for oxy- and deoxyhemoglobin measurement using near-infrared spectroscopy.  

PubMed

In near-infrared spectroscopy (NIRS), concentration changes in oxy- and deoxyhemoglobin are calculated using an attenuation change of the measurement light and by solving a linear equation based on the modified Lambert-Beer law. While solving this equation, we need to know the wavelength-dependent mean optical path lengths of the measurement lights. However, it is very difficult to know these values by a continuous-wave-type (CW-type) system. We propose a new method of estimating wavelength-dependent optical path length ratios of the measurement lights based on the data obtained by a triple wavelength CW-type NIRS instrument. The proposed method does not give a path length itself, but it gives a path length ratio. Thus, it is possible to obtain the accurate hemoglobin concentration changes without cross talk, although the method cannot contribute to the quantification of the absolute magnitude of hemoglobin changes. The method is based on the principle that two possible estimations of hemoglobin concentration changes calculated using a triple-wavelength measurement system should be identical. The method was applied to the experimental data of human subjects' foreheads. The estimated path length ratios were very similar to literature values obtained by using picosecond laser pulses and a streak camera detector [M. Essenpreis et al., Appl. Opt. 32(4), 418-425 (1993)]. PMID:19895139

Umeyama, Shinji; Yamada, Toru

2009-01-01

149

Making the ATHENA optics using silicon pore optics  

NASA Astrophysics Data System (ADS)

Silicon Pore Optics, after 10 years of development, forms now the basis for future large (L) class astrophysics Xray observatories, such as the ATHENA mission to study the hot and energetic universe, matching the L2 science theme recently selected by ESA for launch in 2028. The scientific requirements result in an optical design that demands high angular resolution (5") and large effective area (2 m2 at a few keV) of an X-ray lens with a focal length of 12 to14 m. Silicon Pore Optics was initially based on long (25 to 50 m) focal length telescope designs, which could achieve several arc second angular resolution by curving the silicon mirror in only one direction (conical approximation). With the advent of shorter focal length missions we started to develop mirrors having a secondary curvature, allowing the production of Wolter-I type optics, which are on axis aberration-free. In this paper we will present the new manufacturing process, discuss the impact of the ATHENA optics design on the technology development and present the results of the latest X-ray test campaigns.

Collon, Maximilien J.; Ackermann, Marcelo; Günther, Ramses; Chatbi, Abdelhakim; Vacanti, Giuseppe; Vervest, Mark; Yanson, Alex; Beijersbergen, Marco W.; Bavdaz, Marcos; Wille, Eric; Haneveld, Jeroen; Olde Riekerink, Mark; Koelewijn, Arenda; van Baren, Coen; Müller, Peter; Krumrey, Michael; Burwitz, Vadim; Sironi, Giorgia; Ghigo, Mauro

2014-07-01

150

A focal plane visual motion measurement sensor  

Microsoft Academic Search

A motion detection algorithm, based on biological and computational models, for focal plane implementation has been developed. This Temporal Domain Optical Flow Measurement (TDOFM) algorithm uses computational components which have direct and compact electronic counterparts. It uses a binary image of zero-crossings, 2 level analog signals, the signs of spatiotemporal derivatives, 1-b multiplication and pulse widths to measure image velocity.

Ralph Etienne-Cummings; Jan Van der Spiegel; Paul Mueller

1997-01-01

151

A focal plane visual motion measurement sensor  

Microsoft Academic Search

A motion detection algorithm, based on biological and computational models, for focal plane implementation has been developed. This Temporal Domain Optical Flow Measurement (TDOFM) algorithm uses computational components which have direct and compact electronic counterparts. It uses a binary image of zero-crossings, 2 level analog signals, the signs of spatiotemporal derivatives, 1-b multiplication and pulsewidths to measure image velocity. Compared

Ralph Etienne-Cummings; Jan Van der Spiegel; Paul Mueller

1997-01-01

152

JSim: Simulating the JMAPS Focal Plane  

NASA Astrophysics Data System (ADS)

Developed to support requirements development for the JMAPS (Joint Milli-Arcsecond Pathfinder Survey) mission, JSim is a Python-based focal plane simulator designed to incorporate effects which will affect the astrometric, photometric, and spectroscopic capabilities of the JMAPS satellite. It incorporates noise characteristics, variable point-spread functions, satellite vibrations, and variability in overall satellite parameters such as focal length and detector orientation. In addition to the overall design and capabilities, a set of analyses the simulator has been used for is presented, including investigations into sub-pixel phase error, satellite jitter, and centroiding capability.

Veillette, Daniel

2010-01-01

153

Advanced Information Technology of Slot-Switching Network Schemes for on All-Optical Variable-Length Packet  

Microsoft Academic Search

Problem statement: The purpose of this paper was to investigate all op tical packet switching, because it was the key to the success of the future Internet. It can meet the stringent bandwidth requirement of future Internet applicatio ns, such as real-time video streaming. Due to the lack of optical Random Access Memory (RAM), however, the all-optical schemes studied in

Soung Yue Liew; Edward Sek; Khin Wong; Choong Kwai Fatt

2010-01-01

154

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

E-print Network

Atom optical shop testing of electrostatic lenses using an atom interferometer Ivan Hromada1 of Arizona, Tucson, Arizona 85721, USA (Dated: December 5, 2013) We used an atom interferometer for atom optical shop testing of lenses for atomic de Broglie waves. We measured focal lengths and spherical

Cronin, Alex D.

155

Rapid programmable/code-length-variable, time-domain bit-by-bit code shifting for high-speed secure optical communication.  

PubMed

We propose and experimentally demonstrate a time-domain bit-by-bit code-shifting scheme that can rapidly program ultralong, code-length variable optical code by using only a dispersive element and a high-speed phase modulator for improving information security. The proposed scheme operates in the bit overlap regime and could eliminate the vulnerability of extracting the code by analyzing the fine structure of the time-domain spectral phase encoded signal. It is also intrinsically immune to eavesdropping via conventional power detection and differential-phase-shift-keying (DPSK) demodulation attacks. With this scheme, 10 Gbits/s of return-to-zero-DPSK data secured by bit-by-bit code shifting using up to 1024 chip optical code patterns have been transmitted over 49 km error free. The proposed scheme exhibits the potential for high-data-rate secure optical communication and to realize even one time pad. PMID:21540948

Gao, Zhensen; Dai, Bo; Wang, Xu; Kataoka, Nobuyuki; Wada, Naoya

2011-05-01

156

Zone plates with black focal spots.  

PubMed

Computer-designed linear and circular zone plates are considered that utilize a pi ;-phase jump in order to create destructive interference in the focus. Intensity distributions in the focal plane as well as along the optical axis are calculated for a few examples. A significant decrease of the black spot diameter in comparison with the dimensions of the ordinary focal spot is obtained. Further reduction is achieved when the central region of the zone plate is obstructed. Some applications to alignment and the schlieren technique are suggested. Experimental results that confirm the calculated distributions are presented. PMID:20717392

Viñas, S B; Jaroszewicz, Z; Ko?odziejczyk, A; Sypek, M

1992-01-10

157

Towards Dualband Megapixel QWIP Focal Plane Arrays  

NASA Technical Reports Server (NTRS)

Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024 x 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 (NEDT) of 17 mK at a 95 K operating temperature with f/2.5 optics at 300 K background and the LWIR detector array has demonstrated a NEDT of 13 mK at a 70 K operating temperature with the same optical and background conditions as the MWIR detector array after the subtraction of system noise. Both MWIR and LWIR focal planes have shown background limited performance (BLIP) at 90 K and 70 K operating temperatures respectively, with similar optical and background conditions. In addition, we have demonstrated MWIR and LWIR pixel co-registered simultaneously readable dualband QWIP focal plane arrays. In this paper, we will discuss the performance in terms of quantum efficiency, NEDT, uniformity, operability, and modulation transfer functions of the 1024 x 1024 pixel arrays and the progress of dualband QWIP focal plane array development work.

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

2006-01-01

158

Analysing the structure of the optical path length of a supersonic mixing layer by using wavelet methods  

Microsoft Academic Search

The nano-particle-based planar laser scattering (NPLS) technique is used to measure the density distribution in the supersonic mixing layer of the convective Mach number 0.12, and the optical path difference (OPL), which is quite crucial for the study of aero-optics, is obtained by post processing. Based on the high spatiotemporal resolutions of the NPLS, the structure of the OPL is

Gao Qiong; Yi Shi-He; Jiang Zong-Fu; Zhao Yu-Xin; Xie Wen-Ke

2012-01-01

159

Solid-state curved focal plane arrays  

NASA Technical Reports Server (NTRS)

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.

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

2010-01-01

160

Hiperplasia epitelial focal  

Microsoft Academic Search

Focal epithelial hyperplasia is a rare disease of the oral mucosa caused by the human papilloma virus (HPV). It appears as a benign epithelial growth, usually in the mucosa of the lower lip. It is mainly associated with HPV serotypes 13 and 32 and there is a clear racial predilection for the disease in Native Americans and Eskimos. We describe

E. Vera-Iglesias; M. García-Arpa; P. Sánchez-Caminero; G. Romero-Aguilera; P. Cortina de la Calle

2007-01-01

161

Hiperplasia epitelial focal  

Microsoft Academic Search

Focal epithelial hyperplasia (FEH) is a benign proliferation of the oral mucosa with well defined clinical and histological characteristics. It has been associated with infection of the oral mucosa by types 13 and 32 of the human papillomavirus (HPV), and to a lesser extent, with other types. Its clinical course is variable, although it usually persists for months or years;

Yolanda Delgado; Antonio Torrelo; Isabel Colmenero; Antonio Zambrano

2005-01-01

162

A new modular optical system for large format scene projection  

Microsoft Academic Search

This work will present a new approach to large format projection optics suitable for HWIL testing. Aspects of the design's modular approach and its ability to accommodate widely varying spectral ranges, focal lengths, zoom capabilities and the ability to deliver multi-spectral scene data are presented.

Christopher C. Alexay; Troy A. Palmer

2006-01-01

163

A new modular optical system for large format scene projection  

NASA Astrophysics Data System (ADS)

This work will present a new approach to large format projection optics suitable for HWIL testing. Aspects of the design's modular approach and its ability to accommodate widely varying spectral ranges, focal lengths, zoom capabilities and the ability to deliver multi-spectral scene data are presented.

Alexay, Christopher C.; Palmer, Troy A.

2006-05-01

164

Dense pattern optical multipass cell  

DOEpatents

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.

Silver, Joel A [Santa Fe, NM

2009-01-13

165

Dense Pattern Optical Multipass Cell  

NASA Technical Reports Server (NTRS)

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.

Silver, Joel A. (Inventor)

2009-01-01

166

MWIR and LWIR Megapixel QWIP Focal Plane Arrays  

NASA Technical Reports Server (NTRS)

A mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 1024x1024 pixel quantum well infrared photodetector (QWIP) focal plane array has been demonstrated with excellent imagery. MWIR focal plane has given noise equivalent differential temperature (NETD) of 19 mK at 95K operating temperature with f/2.5 optics at 300K background and LWIR focal plane has given NEDT of 13 mK at 70K operating temperature with same optical and background conditions as MWIR array. Both of these focal plane arrays have shown background limited performance (BLIP) at 90K and 70K operating temperatures with the same optics and background conditions. In this paper, we will discuss their performance in quantum efficiency, NETD, uniformity, and operability.

Gunapala, Sarath D.; Bandara, S. V.; Liu, J. K.; Rafol, S. B.; Thang, J.; Mumolo, Jason; Tidrow, M.; LeVan, P. D.; Hill, C.

2004-01-01

167

Analysing the structure of the optical path length of a supersonic mixing layer by using wavelet methods  

NASA Astrophysics Data System (ADS)

The nano-particle-based planar laser scattering (NPLS) technique is used to measure the density distribution in the supersonic mixing layer of the convective Mach number 0.12, and the optical path difference (OPL), which is quite crucial for the study of aero-optics, is obtained by post processing. Based on the high spatiotemporal resolutions of the NPLS, the structure of the OPL is analysed using wavelet methods. The coherent structures of the OPL are extracted using three methods, including the methods of thresholding the coefficients of the orthogonal wavelet transform and the wavelet packet transform, and preserving a number of wavelet packet coefficients with the largest amplitudes determined by the entropy dimension. Their performances are compared, and the method using the wavelet packet is the best. Based on the viewpoint of multifractals, we study the OPL by the wavelet transform maxima method (WTMM), and the result indicates that its scaling behaviour is evident.

Gao, Qiong; Yi, Shi-He; Jiang, Zong-Fu; Zhao, Yu-Xin; Xie, Wen-Ke

2012-06-01

168

Formation of multiple focal spots using a high NA lens with a complex spiral phase mask  

NASA Astrophysics Data System (ADS)

The formation of a transversally polarized beam by transmitting a tightly focused double-ring-shaped azimuthally polarized beam through a complex spiral phase mask and high numerical aperture lens is presented based on vector diffraction theory. The generation of transversally polarized focal spot segment splitting and multiple focal spots is illustrated numerically. Moreover, we found that a properly designed complex spiral phase mask can move the focal spots along the optical axis in the z direction. Therefore, one can achieve a focal segment of two, three or multiple completely transversely polarized focal spots, which finds applications in optical trapping and in material processing technologies.

Lalithambigai, K.; Anbarasan, P. M.; Rajesh, K. B.

2014-07-01

169

Inherited focal, episodic neuropathies  

Microsoft Academic Search

Hereditary neuropathy with liability to pressure palsies (HNPP; also called tomaculous neuropathy) is an autosomal-dominant\\u000a disorder that produces a painless episodic, recurrent, focal demyelinating neuropathy. HNPP generally develops during adolescence,\\u000a and may cause attacks of numbness, muscular weakness, and atrophy. Peroneal palsies, carpal tunnel syndrome, and other entrapment\\u000a neuropathies may be frequent manifestations of HNPP. Motor and sensory nerve conduction

Phillip F. Chance

2006-01-01

170

Focal cortical dysplasia – review  

PubMed Central

Summary Focal cortical dysplasia is a malformation of cortical development, which is the most common cause of medically refractory epilepsy in the pediatric population and the second/third most common etiology of medically intractable seizures in adults. Both genetic and acquired factors are involved in the pathogenesis of cortical dysplasia. Numerous classifications of the complex structural abnormalities of focal cortical dysplasia have been proposed – from Taylor et al. in 1971 to the last modification of Palmini classification made by Blumcke in 2011. In general, three types of cortical dysplasia are recognized. Type I focal cortical dysplasia with mild symptomatic expression and late onset, is more often seen in adults, with changes present in the temporal lobe. Clinical symptoms are more severe in type II of cortical dysplasia usually seen in children. In this type, more extensive changes occur outside the temporal lobe with predilection for the frontal lobes. New type III is one of the above dysplasias with associated another principal lesion as hippocampal sclerosis, tumor, vascular malformation or acquired pathology during early life. Brain MRI imaging shows abnormalities in the majority of type II dysplasias and in only some of type I cortical dysplasias. The most common findings on MRI imaging include: focal cortical thickening or thinning, areas of focal brain atrophy, blurring of the gray-white junction, increased signal on T2- and FLAIR-weighted images in the gray and subcortical white matter often tapering toward the ventricle. On the basis of the MRI findings, it is possible to differentiate between type I and type II cortical dysplasia. A complete resection of the epileptogenic zone is required for seizure-free life. MRI imaging is very helpful to identify those patients who are likely to benefit from surgical treatment in a group of patients with drug-resistant epilepsy. However, in type I cortical dysplasia, MR imaging is often normal, and also in both types the lesion seen on MRI may be smaller than the seizure-generating region seen in the EEG. The abnormalities may also involve vital for life brain parts, where curative surgery will not be an option. Therefore, other diagnostic imaging techniques such as FDG PET, MEG, DTI and intra-cranial EEG are widely used to establish the diagnosis and to decide on management. With advances in both genetics and neuroimaging, we may develop a better understanding of patients with drug-resistant epilepsy, which will help us to provide more successful pharmacological and/or surgical treatment in the future. PMID:22844307

Kabat, Joanna; Król, Przemys?aw

2012-01-01

171

A combined electron beam/optical lithography process step for the fabrication of sub-half-micron-gate-length MMIC chips  

NASA Technical Reports Server (NTRS)

Advanced radar and communication systems rely heavily on state-of-the-art microelectronics. Systems such as the phased-array radar require many transmit/receive (T/R) modules which are made up of many millimeter wave - microwave integrated circuits (MMIC's). The heart of a MMIC chip is the Gallium Arsenide (GaAs) field-effect transistor (FET). The transistor gate length is the critical feature that determines the operating frequency of the radar system. A smaller gate length will typically result in a higher frequency. In order to make a phased array radar system economically feasible, manufacturers must be capable of producing very large quantities of small-gate-length MMIC chips at a relatively low cost per chip. This requires the processing of a large number of wafers with a large number of chips per wafer, minimum processing time, and a very high chip yield. One of the bottlenecks in the fabrication of MIMIC chips is the transistor gate definition. The definition of sub-half-micron gates for GaAs-based field-effect transistors is generally performed by direct-write electron beam lithography (EBL). Because of the throughput limitations of EBL, the gate-layer fabrication is conventionally divided into two lithographic processes where EBL is used to generate the gate fingers and optical lithography is used to generate the large-area gate pads and interconnects. As a result, two complete sequences of resist application, exposure, development, metallization and lift-off are required for the entire gate structure. We have baselined a hybrid process, referred to as EBOL (electron beam/optical lithography), in which a single application of a multi-level resist is used for both exposures. The entire gate structure, (gate fingers, interconnects and pads), is then formed with a single metallization and lift-off process. The EBOL process thus retains the advantages of the high-resolution E-beam lithography and the high throughput of optical lithography while essentially eliminating an entire lithography/metallization/lift-off process sequence. This technique has been proven to be reliable for both trapezoidal and mushroom gates and has been successfully applied to metal-semiconductor and high-electron-mobility field-effect transistor (MESFET and HEMT) wafers containing devices with gate lengths down to 0.10 micron and 75 x 75 micron gate pads. The yields and throughput of these wafers have been very high with no loss in device performance. We will discuss the entire EBOL process technology including the multilayer resist structure, exposure conditions, process sensitivities, metal edge definition, device results, comparison to the standard gate-layer process, and its suitability for manufacturing.

Sewell, James S.; Bozada, Christopher A.

1994-01-01

172

Standard Length versus Total Length  

Microsoft Academic Search

In an effort to determine the length measurement most representative of the bulk of the fish, the standard length and the total length were each compared with the weight of the fish. This comparison was made for four species of game fish, yellow perch (Perca flavescens), wall-eyed pike (Stizostedion v. vitreum), rock bass (Ambloplites rupestris), and lake trout (Cristivomer n.

William F. Royce

1942-01-01

173

Theoretical and experimental analysis of basic parameters of two-element optical systems.  

PubMed

Our work presents detailed theoretical analysis of two-element optical systems of telephoto lenses and objectives of anallactic telescopes with internal focusing. The first element of such systems has positive optical power and the second element has negative optical power. This type of optical system is widespread in practice mainly in the field of photographic lenses and in surveying instruments (theodolites, leveling instruments, etc.) where the anallactic telescope with internal focusing is being used. In our work we propose methods to determine the basic parameters of such objectives, i.e., the focal lengths of both the elements of the objective lens and their mutual axial separation. Furthermore, the detailed analysis of aberration properties of such optical systems is performed and methods for measuring the focal lengths of individual elements and their mutual distance without the need for disassembling the investigated optical system are presented. PMID:23089783

Mikš, Antonín; Novák, Pavel

2012-10-20

174

Test chamber for low-background IR focal plane testing  

NASA Technical Reports Server (NTRS)

A unique and versatile vacuum chamber has been designed for JPL's IR Focal Plane Technology Group. This chamber is equipped with multiple ports for cryogen and electrical vacuum feedthroughs, pumping units, vacuum gages, sources, and detector camera heads. The design incorporates a liquid-nitrogen-cooled optical table and radiation shield for low-background IR detector testing. Focal planes can be tested at temperatures ranging from 300 K to that of liquid helium. This paper describes the design and construction of this low-background IR focal plane test chamber and discusses some of its distinctive features. An analysis of the test chamber's performance is also presented.

Staller, Craig; Capps, Richard W.; Butler, Douglas; Moss, Nancy; Norwood, Wynn

1989-01-01

175

Math Focal Points: Grade 5  

NSDL National Science Digital Library

For teachers of grade 5, NCTM offers online resources, many interactive, that support teaching of the specific areas defined by NCTM as Focal Points. Focal points are clusters of related knowledge, skills, and concepts, and for Grade 5 they are Division of Whole Numbers, Fractions and Decimals and 3-D Shapes. Commentary and links to Focal Points for grades K-8 are provided. Links to background information and further training opportunities are provided.

Herrera, Terese A.

2011-09-19

176

Focal osseous dysplasia.  

PubMed

Focal osseous dysplasia (FOD) is one of the benign fibro-osseous lesions of the jaw bones and the most commonly occuring benign fibro-osseous lesion. This entity occurs more commonly in females and has a predilection for African Americans. Radiographically, the lesion has a variable appearance depending on the duration but may appear as a radiolucent to radiopaque lesion that can be well to poorly defined. Hisotologically, when biopsied, there are fragments of bony trabeculae intermixed with fibrous stroma with incomplete stromal vasculature. The main differential diagnosis is with ossifying fibroma, which is neoplastic while FOD is considered a reactive process. Most patients with FOD may be followed clinically without surgical intervention. PMID:21744106

Potochny, Evelyn M; Huber, Aaron R

2011-09-01

177

Intelligent Optical Systems Using Adaptive Optics  

NASA Technical Reports Server (NTRS)

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.

Clark, Natalie

2012-01-01

178

On the Meaning of Focalization  

Microsoft Academic Search

\\u000a In this paper, we use Girard’s ludics to analyze focalization, a fundamental property of the proof theory of linear logic.\\u000a In particular, we show how focalization can be realized interactively thanks to suitable section-retraction pairs between\\u000a semantical types.

Michele Basaldella; Alexis Saurin; Kazushige Terui

2011-01-01

179

Statistical earthquake focal mechanism forecasts  

E-print Network

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 ...

Kagan, Yan Y

2013-01-01

180

Effect of annular obstruction and numerical aperture in the focal region of high NA objective lens  

NASA Astrophysics Data System (ADS)

In this article, based on the vector diffraction theory, the effect of annular apodization and numerical aperture in the focal region of tightly focused azimuthally polarized Bessel Gaussian beam by high NA lens is investigated numerically. The results show that our proposed system generates a longitudinally polarized beam in sub wavelength focal spot having large uniform focal depth of incident beam with annular aperture for lower NA. Such kind of subwavelength focal segment may find wide applications in optical traps, biological applications, atmospheric sciences and optical manipulation technology.

Suresh, P.; Rajesh, K. B.; Sivasubramonia Pillai, T. V.; Jaroszewicz, Z.

2014-05-01

181

Megapixel Multi-band QWIP Focal Plane Arrays  

NASA Technical Reports Server (NTRS)

A mid-wavelength 1024x1024 pixel quantum well infrared photodetector (QW) focal plane array has been demonstrated with excellent imagery. Noise equivalent differential temperature (NETD) of 19 mK was achieved at 95K operating temperature with f/2.5 optics at 300K background. This focal plane array has shown background limited performance (BLIP) at 90K operating temperature with the same optics and background conditions. In this paper, we will discuss its performance in quantum efficiency, NETD, uniformity, and operability.

Gunapala, S. D.; Bandara, S. V.; Liu, J. K.; Rafo, S. B.; Hill, C.; Mumolo, J.; Thang, J.; Tidrow, M.; LeVan, P. D.

2004-01-01

182

Electro-optically actuated liquid-lens zoom  

NASA Astrophysics Data System (ADS)

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.

Pütsch, O.; Loosen, P.

2012-06-01

183

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

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

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

2006-01-01

184

Demonstration of a Horseshoe-Shaped Longitudinal Focal Profile  

SciTech Connect

The three-dimensional laser focal region has been spatially shaped so that in the focal plane the transverse intensity distribution is centrally peaked, whereas at multiple defocused planes along the laser propagation direction, the distribution is annular. The longitudinal profile of such a shaped laser focal volume is approximately in the form of a “horseshoe.” The horseshoe-shaped longitudinal profile was realized experimentally from a single laser beam by the incoherent coaxial combination of Laguerre–Gaussian and Gaussian modes generated from segmented optical elements. The ponderomotive forces associated with this three-dimensional focal intensity distribution can potentially generate a quasi-collimated, forward-directed bunch of electrons from a low-density gas target at high laser intensities.

Brijesh, P.; Kessler, T.J.; Zuegel, J.D.; Meyerhofer, D.D.

2007-03-26

185

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

SciTech Connect

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.

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

186

Finger Length  

NSDL National Science Digital Library

Although life experience plays a huge role in shaping who we are, the foundations of our personality begin in the womb. This Science Update describes a recent study that looks to finger length for signs of a man's pre-natal exposure to testosterone.

Science Update;

2005-03-28

187

Finger Length  

NSDL National Science Digital Library

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.

American Association for the Advancement of Science (;)

2005-03-28

188

Statistical Earthquake Focal Mechanism Forecasts  

NASA Astrophysics Data System (ADS)

The new whole Earth focal mechanism forecast, based on the GCMT catalog, has been created. In the present forecast, the sum of normalized seismic moment tensors within 1000 km radius is calculated and the P- and T-axes for the focal mechanism are evaluated on the basis of the sum. Simultaneously we calculate an average rotation angle between the forecasted mechanism and all the surrounding mechanisms. This average angle shows tectonic complexity of a region and indicates the accuracy of the prediction. The method was originally proposed by Kagan and Jackson (1994, JGR). Recent interest by CSEP and GEM has motivated some improvements, particularly to extend the previous forecast to polar and near-polar regions. The major problem in extending the forecast is the focal mechanism calculation on a spherical surface. In the previous forecast as our average focal mechanism was computed, it was assumed that longitude lines are approximately parallel within 1000 km radius. This is largely accurate in the equatorial and near-equatorial areas. However, when one approaches the 75 degree latitude, the longitude lines are no longer parallel: the bearing (azimuthal) difference at points separated by 1000 km reach about 35 degrees. In most situations a forecast point where we calculate an average focal mechanism is surrounded by earthquakes, so a bias should not be strong due to the difference effect cancellation. But if we move into polar regions, the bearing difference could approach 180 degrees. In a modified program focal mechanisms have been projected on a plane tangent to a sphere at a forecast point. New longitude axes which are parallel in the tangent plane are corrected for the bearing difference. A comparison with the old 75S-75N forecast shows that in equatorial regions the forecasted focal mechanisms are almost the same, and the difference in the forecasted focal mechanisms rotation angle is close to zero. However, though the forecasted focal mechanisms are similar, closer to the 75 latitude degree, the difference in the rotation angle is large (around a factor 1.5 in some places). The Gamma-index was calculated for the average focal mechanism moment. A non-zero Index indicates that earthquake focal mechanisms around the forecast point have different orientations. Thus deformation complexity displays itself in the average rotation angle and in the Index. However, sometimes the rotation angle is close to zero, whereas the Index is large, testifying to a large CLVD presence. Both new 0.5x0.5 and 0.1x0.1 degree forecasts are posted at http://eq.ess.ucla.edu/~kagan/glob_gcmt_index.html.

Kagan, Y. Y.; Jackson, D. D.

2013-12-01

189

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

Microsoft Academic Search

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

Adrian Glasser; Melanie C. W. Campbell

1999-01-01

190

Focal spot calibration in a digital breast tomosynthesis system  

NASA Astrophysics Data System (ADS)

Digital breast tomosynthesis (DBT) technology is a promising modality for the early detection of breast cancer and could provide clear diagnostic images in which the effect of tissue overlap is alleviated. Accurate calibration of the system geometry is essential for successful image reconstruction in DBT systems. The geometrical calibration of the focal spot in the X-ray tube at the detector plane is one of the most critical parameters of a DBT system. In this paper, a new method using a multi-hole collimator and an iterative calibration algorithm is reported in order to estimate the position of the focal spot at the detector plane. The iterative algorithm is based on the area-distance relationship in the collimator image. The linearity of this relationship has been verified both empirically and theoretically. A focal spot estimate has been achieved regardless of the location of the focal spot in the image. A total of 15 projection images acquired with the DBT system have been successfully reconstructed with geometric information about the focal spot position provided by our new method, and the focal spot estimate method proposed in this paper could be a useful solution for locating optical sources that cannot be viewed or accessed.

Choi, Jaegu; Hwang, Sun-Jo; Choi, Young-Wook

2012-05-01

191

Imaging optically scattering objects with ultrasound-modulated optical tomography  

E-print Network

where ultra- sound interacts with light [15­17]. In this Letter, for the first time to our knowledge, we central frequency, 25.4 mm lens diam- eter, 38 mm focal length, 2 mm focal zone width, and 20 mm focal

Wang, Lihong

192

ORFEUS focal plane instrumentation: The Berkeley spectrometer  

NASA Technical Reports Server (NTRS)

A spectrograph for the ORFEUS mission that incorporates four varied line-space, spherically figured diffraction gratings was designed. The ORFEUS, a 1-m normal incidence telescope is equipped with 2 focal plane spectrographs. The Berkeley spectrograph was developed with an optimizing raytracing computer code. Each grating accepts the light from 20 percent of the aperture of the telescope primary mirror and has a unique set of characteristics to cover a sub-bandpass within the 390 to 1200 A spectral range. Two photon-counting detectors incorporating a time delay readout system are used to record the spectra from all four gratings simultaneously. The nominal design achieves a spectral resolution (FWHM) in excess of 5500 at all wavelengths within the bandpass. The resolution is limited primarily by the detector spatial resolution. The 1 sigma astigmatism of this design varies between 13 and 150 micrometer on the same focal surface. An independent, direct imaging system tracks the drift of the target within the spectrometer aperture and allows measurement of the misalignment between the telescope optical axis and that of the external star tracker. The resolution and astigmatism achievable with this design are superior to those of a standard Rowland spectrograph designed with the same constraints.

Hurwitz, Mark; Bowyer, Stuart

1988-01-01

193

Combining Single-Molecule Optical Trapping and Small-Angle X-Ray Scattering Measurements to Compute the Persistence Length of a Protein ER/K [alpha]-Helix  

SciTech Connect

A relatively unknown protein structure motif forms stable isolated single {alpha}-helices, termed ER/K {alpha}-helices, in a wide variety of proteins and has been shown to be essential for the function of some molecular motors. The flexibility of the ER/K {alpha}-helix determines whether it behaves as a force transducer, rigid spacer, or flexible linker in proteins. In this study, we quantify this flexibility in terms of persistence length, namely the length scale over which it is rigid. We use single-molecule optical trapping and small-angle x-ray scattering, combined with Monte Carlo simulations to demonstrate that the Kelch ER/K {alpha}-helix behaves as a wormlike chain with a persistence length of 15 nm or 28 turns of {alpha}-helix. The ER/K {alpha}-helix length in proteins varies from 3 to 60 nm, with a median length of 5 nm. Knowledge of its persistence length enables us to define its function as a rigid spacer in a translation initiation factor, as a force transducer in the mechanoenzyme myosin VI, and as a flexible spacer in the Kelch-motif-containing protein.

Sivaramakrishnan, S.; Sung, J.; Ali, M.; Doniach, S.; Flyvbjerg, H.; Spudich, J.A.; (Stanford); (Danmarks)

2010-01-12

194

Microlens array based LCD projection display with software-only focal distance control  

NASA Astrophysics Data System (ADS)

State of the art LED pico-projectors using single-channeled optical layouts are always constricted by a trade-off between achievable flux and minimum system size. Furthermore, their limited depth of focus require additional mechanically moving components for focusing if variable projection distances are essential for their specific application. We present a novel microlens-array based LCD projector breaking these constraints of conventional LED illuminated systems, thus enabling a super compact, robust and bright module while offering new features for electronic focal distance control without additional mechanical components. While the short focal length of each contributing channel maintains a certain system slimness, the superposition of all individual projections on a screen done by image-preprocessing leads to dramatic flux enhancement without blurring effects. Starting with a description of the working principle of array projection we focus on key properties regarding depth of focus for examining novel image-preprocessing algorithms that enable for only software-controlled focal distance. Further improved program code enables sharp images even onto freeform screen geometries. The realized prototype utilizes a transmissive LCD microdisplay along with a monolithic array of 45 microlenses actively aligned to the top of the display coverglass. While the display is illuminated by a collimated white LED; each channel is assigned to one primary color by applying a color filter array buried below the microlenses to obtain a full color image on the screen. The displayed image content is controlled via PC by a novel software tool, whose correct operation is verified by experimental results.

Sieler, Marcel; Schreiber, Peter; Bräuer, Andreas

2013-03-01

195

Focal process of the great Chilean earthquake May 22, 1960  

Microsoft Academic Search

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

Hiroo Kanamori; John J. Cipar

1974-01-01

196

SNAP satellite focal plane development  

Microsoft Academic Search

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

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

197

Body length assortative shoaling in the European minnow, Phoxinus phoxinus  

Microsoft Academic Search

We investigated the functional aspects of active shoal choice behaviour and its role in generating body length assortative fish shoals. We presented single European minnows with a choice between two conspecific shoals of equal number, one of which consisted of fish of similar body length and the other of fish that were smaller or larger than the focal fish. The

Ashley J. W. Ward; Jens Krause

2001-01-01

198

Persistent Focal Behavior and Physical Activity Performance  

ERIC Educational Resources Information Center

This article examines the proclivity and performance attributes of focal students across time and activities using data from 9,345 students. Three systematic focal behavior partitions are examined: Across activities, across time, and across activities and time. A student's performance is focal if it ends in 0 or 5 for push-ups and 0 for…

Erfle, Stephen E.

2014-01-01

199

The inner lives of focal adhesions  

Microsoft Academic Search

In focal adhesions of eukaryotic cells, transmembrane receptors of the integrin family and a large set of adaptor proteins form the physical link between the extracellular substrate and the actin cytoskeleton. During cell migration, nascent focal adhesions within filopodia and lamellipodia make the initial exploratory contacts with the cellular environment, whereas maturing focal adhesions pull the cell forward against the

Bernhard Wehrle-Haller; Beat A Imhof

2002-01-01

200

Focalization in 3D Video Games  

Microsoft Academic Search

This paper investigates Bal's concept of focalization for 3D video games. First, the argument traces focalization in the historical development of camera strategies in 3D video games. It highlights the detachment of the camera into an own interactive operator. Then, it exemplifies the visual focalization in video games using two case studies. In the following, it looks at possible problems

Michael Nitsche

201

A simple method for quality evaluation of micro-optical components based on 3D IPSF measurement.  

PubMed

This paper presents a simple method based on the measurement of the 3D intensity point spread function for the quality evaluation of high numerical aperture micro-optical components. The different slices of the focal volume are imaged thanks to a microscope objective and a standard camera. Depending on the optical architecture, it allows characterizing both transmissive and reflective components, for which either the imaging part or the component itself are moved along the optical axis, respectively. This method can be used to measure focal length, Strehl ratio, resolution and overall wavefront RMS and to estimate optical aberrations. The measurement setup and its implementation are detailed and its advantages are demonstrated with micro-ball lenses and micro-mirrors. This intuitive method is adapted for optimization of micro-optical components fabrication processes, especially because heavy equipments and/or data analysis are not required. PMID:24921515

Baranski, Maciej; Perrin, Stephane; Passilly, Nicolas; Froehly, Luc; Albero, Jorge; Bargiel, Sylwester; Gorecki, Christophe

2014-06-01

202

Benefits of oversampled small pixel focal plane arrays  

NASA Astrophysics Data System (ADS)

Infrared Focal Plane Arrays have been developed with reductions in pixel size below the Nyquist limit imposed by the optical systems Point Spread Function (PSF). These smaller sub diffraction limited pixels allows spatial oversampling of the image. We show that oversampling the PSF allows improved fidelity in imaging, resulting in sensitivity improvements due to pixel correlation, reduced false alarm rates, improved detection ranges, and an improved ability to track closely spaced objects.

Caulfield, John T.; Wilson, Jerry A.; Dhar, Nibir K.

2014-06-01

203

Focal plane detectors possible detector technologies for OWL/AIRWATCH  

SciTech Connect

New satellite-born projects OWL and AIRWATCH will need single-photon focal-plane detectors of a million pixels in a design which is optimized to the focusing optics and electronics at acceptable cost. We discuss different phototube possibilities and their pros and cons with crude cost estimates. We conclude that a multichannel-photomultiplier solution is safe. A better compromise may be to adapt a 6 or 9 inch X-ray image intensifier tube or develop a 12 inch image intensifier for detecting individual photons, and adapt the optics to have many mirror modules. The possibility of developing super-large-area phototubes is also discussed.

Flyckt, Esso [Photonis SAS, BP250, F-18106 Brive (France)

1998-06-15

204

Development of a cable reel development system using a rotary joint for kilometer lengths of two-fiber multi-mode fiber optic cable  

SciTech Connect

Brookhaven National Laboratory (BNL) recently developed a two-component system for use during remote inspections. The system consists of a mobile unit with television cameras and other equipment and a stationary base station. A variety of signals must be continually transmitted between the two system components as the mobile unit is moved from the location to another. Two channels of broadband (10MHz) NTSC video are transmitted from the mobile unit to the base station, and a bi-directional ``talk set`` provides audio communication between personnel at each location. In addition, several channels of RS-232 are required to support present and future instruments used at the mobile unit and controlled by personnel at the base station. Brookhaven developed a mobile unit which communicated with a base station over a 2-fiber multimode fiber optic cable. One of the design requirements was maintaining constant communication with the base station during the time the mobile unit was moved about. To provide uninterrupted communications, deployment of the 1-km long fiber optic cable was initially performed with a ``spinning reel`` mechanism. The spinning reel mechanism proved to be mechanically unsuitable, and so the cable deployment mechanism was redesigned to spool the cable off the reel. The requirement for uninterrupted communications required a two-channel fiber optic rotary joint in the design. Incorporation of the rotary joint into the design is described, and appropriate reference material is included.

Curtiss, J.A.; Jahelka, J.R.

1995-08-11

205

Optical imaging of shock waves produced by a high-energy electromagnetic transducer.  

PubMed

An electromagnetic acoustic transducer (EMAT) and acoustic lens have been constructed to provide reproducible and well characterized acoustic shock waves in water. The peak pressure amplitude variation for the unfocused and focused shock waves was found to be within +/- 5%. The focal region has been characterized both optically and by conventional piezoelectric pressure measurements. Optical investigations centre around ruby laser illuminated Schlieren and focused shadow imaging. The temporal resolution of the optical technique was determined by the ruby laser pulse length of 20 ns, giving a spatial resolution of 30 microns for a shock front in water. PMID:8272433

Carnell, M T; Alcock, R D; Emmony, D C

1993-11-01

206

Mechanical properties of individual focal adhesions probed with a magnetic microneedle  

Microsoft Academic Search

A permanent magnetic microneedle was developed to apply tensional forces to integrin receptors via ligand-coated magnetic microbeads while optically analyzing the mechanical properties of individual focal adhesions. Force application (130pN for 3s) through activated ?1 integrins produced less bead displacement than when unligated integrins were stressed. This strengthening response differed markedly on a bead-by-bead basis, correlated directly with local focal

Benjamin D. Matthews; Darryl R. Overby; Francis J. Alenghat; John Karavitis; Yasuchi Numaguchi; Philip G. Allen; Donald E. Ingbera

2004-01-01

207

Design of the fiber optic support system and fiber bundle accelerated life test for VIRUS  

Microsoft Academic Search

The quantity and length of optical fibers required for the Hobby-Eberly Telescope* Dark Energy eXperiment (HETDEX) create unique fiber handling challenges. For HETDEX‡, at least 33,600 fibers will transmit light from the focal surface of the telescope to an array of spectrographs making up the Visible Integral-Field Replicable Unit Spectrograph (VIRUS). Up to 96 Integral Field Unit (IFU) bundles, each

Ian M. Soukup; Joseph H. Beno; Richard J. Hayes; James T. Heisler; Jason R. Mock; Nicholas T. Mollison; John M. Good; Gary J. Hill; Brian L. Vattiat; Jeremy D. Murphy; Seth C. Anderson; Svend M. Bauer; Andreas Kelz; Martin M. Roth; Eric P. Fahrenthold

2010-01-01

208

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

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

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

2014-01-01

209

Focal axis resolver for offset reflector antennas  

NASA Technical Reports Server (NTRS)

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.

Schmidt, R. F. (inventor)

1983-01-01

210

Focal adhesion regulation of cell behavior  

Microsoft Academic Search

Focal adhesions lie at the convergence of integrin adhesion, signaling and the actin cytoskeleton. Cells modify focal adhesions in response to changes in the molecular composition, two-dimensional (2D) vs. three-dimensional (3D) structure, and physical forces present in their extracellular matrix environment. We consider here how cells use focal adhesions to regulate signaling complexes and integrin function. Furthermore, we examine how

Michele A Wozniak; Katarzyna Modzelewska; Lina Kwong; Patricia J Keely

2004-01-01

211

Athermal design for infrared refractive, diffractive, reflective hybrid optical system  

NASA Astrophysics Data System (ADS)

Thermal properties and dispersive capacity of diffractive optical elements were expounded in this paper, and the conclusion that optothermal expansion coefficient of diffractive optical element is independent of refractive index of the material was derived. The design method to athermalize the hybrid infrared optical system was studied, a new hybrid system with diffractive surface was structured on the foundation of refractive/reflective optical system using optical design software ZEMAX, and the surface was simulated by MATLAB. The image quality was improved obviously compared with the one without diffractive surface. The system worked at 3.7~4.8?m band with its' effective focal length of 70mm, field of view of 2° and possessed better athermal performance in the temperature range -40°~+60°. The image quality achieved diffractive limit, besides, a compact structure, small volume and light weight were other advantages of the hybrid system.

Cheng, Ximin; Xie, Weimin; Bai, Yu; Jia, Xin; Xing, Tingwen

2014-09-01

212

Focal adhesion size uniquely predicts cell migration  

PubMed Central

Focal adhesions are large protein complexes organized at the basal surface of cells, which physically connect the extracellular matrix to the cytoskeleton and have long been speculated to mediate cell migration. However, whether clustering of these molecular components into focal adhesions is actually required for these proteins to regulate cell motility is unclear. Here we use quantitative microscopy to characterize descriptors of focal adhesion and cell motility for mouse embryonic fibroblasts and human fibrosarcoma cells, across a wide range of matrix compliance and following genetic manipulations of focal adhesion proteins (vinculin, talin, zyxin, FAK, and paxilin). This analysis reveals a tight, biphasic gaussian relationship between mean size of focal adhesions (not their number, surface density, or shape) and cell speed. The predictive power of this relationship is comprehensively validated by disrupting nonfocal adhesion proteins (?-actinin, F-actin, and myosin II) and subcellular organelles (mitochondria, nuclear DNA, etc.) not known to affect either focal adhesions or cell migration. This study suggests that the mean size of focal adhesions robustly and precisely predicts cell speed independently of focal adhesion surface density and molecular composition.—Kim, D.-H., Wirtz, D. Focal adhesion size uniquely predicts cell migration. PMID:23254340

Kim, Dong-Hwee; Wirtz, Denis

2013-01-01

213

Optimal focal-plane restoration  

NASA Technical Reports Server (NTRS)

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.

Reichenbach, Stephen E.; Park, Stephen K.

1989-01-01

214

Neurocysticercosis presenting as focal hydrocephalus.  

PubMed

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

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

2014-01-01

215

Single-mode laser studies: Design and performance of a fixed-wave length source and coupling of lasers to thin-film optical waveguides  

NASA Technical Reports Server (NTRS)

A module developed for the generation of a stable single wavelength to be used for a fiber optic multiplexing scheme is described. The laser is driven with RZ pulses, and the temperature is stabilized thermoelectrically. The unit is capable of maintaining a fixed wavelength within about 6 A as the pulse duty cycle is changed between 0 and 100 percent. This is considered the most severe case, and much tighter tolerances are obtainable for constant input power coding schemes. Using a constricted double heterostructure laser, a wavelength shift of 0.083 A mA is obtained due to laser self-heating by a dc driving current. The thermoelectric unit is capable of maintaining a constant laser heat-sink temperature within 0.02 C. In addition, miniature lenses and couplers are described which allow efficient coupling of single wavelength modes of junction lasers to thin film optical waveguides. The design of the miniature cylinder lenses and the prism coupling techniques allow 2 mW of single wavelength mode junction laser light to b coupled into thin film waveguides using compact assemblies. Selective grating couplers are also studied.

Ladany, I.; Hammer, J. M.

1980-01-01

216

High operating temperature interband cascade focal plane arrays  

NASA Astrophysics Data System (ADS)

In this paper, we report the initial demonstration of mid-infrared interband cascade (IC) photodetector focal plane arrays with multiple-stage/junction design. The merits of IC photodetectors include low noise and efficient photocarrier extraction, even for zero-bias operation. By adopting enhanced electron barrier design and a total absorber thickness of 0.7 ?m, the 5-stage IC detectors show very low dark current (1.10 × 10-7 A/cm2 at -5 mV and 150 K). Even with un-optimized fabrication and standard commercial (mis-matched) read-out circuit technology, infrared images are obtained by the 320 × 256 IC focal plane array up to 180 K with f/2.3 optics. The minimum noise equivalent temperature difference of 28 mK is obtained at 120 K. These initial results indicate great potential of IC photodetectors, particularly for high operating temperature applications.

Tian, Z.-B.; Godoy, S. E.; Kim, H. S.; Schuler-Sandy, T.; Montoya, J. A.; Krishna, S.

2014-08-01

217

Adaptive beam shaping by controlled thermal lensing in optical elements.  

PubMed

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 through dynamic heating of an optical element by an external pump beam. The system is especially suitable for use in interferometric gravitational wave interferometers employing high laser power, allowing for in situ control of the laser modal properties and compensation for thermal lensing of the primary laser. Using CO(2) laser heating of fused-silica substrates, we demonstrate a focal length variable from infinity to 4.0 m, with a slope of 0.082 diopter/W of absorbed heat. For on-axis operation, no higher-order modes are introduced by the adaptive optical element. Theoretical modeling of the induced optical path change and predicted thermal lens agrees well with measurement. PMID:17415383

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

2007-04-20

218

Terahertz detectors and focal plane arrays  

NASA Astrophysics Data System (ADS)

Terahertz (THz) technology is one of emerging technologies that will change our life. A lot of attractive applications in security, medicine, biology, astronomy, and non-destructive materials testing have been demonstrated already. However, the realization of 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. As a result, THz radiation is resistant to the techniques commonly employed in these well established neighbouring bands. In the paper, issues associated with the development and exploitation of THz radiation detectors and focal plane arrays are discussed. Historical impressive progress in THz detector sensitivity in a period of more than half century is analyzed. More attention is put on the basic physical phenomena and the recent progress in both direct and heterodyne detectors. After short description of general classification of THz detectors, more details concern Schottky barrier diodes, pair braking detectors, hot electron mixers and field-effect transistor detectors, where links between THz devices and modern technologies such as micromachining are underlined. Also, the operational conditions of THz detectors and their upper performance limits are reviewed. Finally, recent advances in novel nanoelectronic materials and technologies are described. It is expected that applications of nanoscale materials and devices will open the door for further performance improvement in THz detectors.

Rogalski, A.; Sizov, F.

2011-09-01

219

Focal Molography: Coherent Microscopic Detection of Biomolecular Interaction  

NASA Astrophysics Data System (ADS)

We introduce and theoretically investigate here a novel analytical method that we have called focal molography, in which molecular interactions are made visible through scattering of coherent light by a coherent pattern of molecules. The scattered light quantifies the presence of molecules at molecular interaction sites. It is separated from noncoherent background scatter by a combination of local dark-field illumination, interference enhancement, and spatial filtering. The latter is achieved by holographic focusing of the wave field generated by the coherently assembled molecules onto an Airy disk and by subtraction of the noncoherent irradiance in the focal plane outside the disk from the irradiance in the disk. This new microscopic method allows distinct detection of low-refractive-index contrast in the nanoenvironment of biomolecules from which information on the interaction of the coherently assembled molecules with molecules in a liquid or gaseous sample may be deduced. The noncoherent surroundings of the coherently assembled molecules consist of freely diffusing solvent and solute molecules. The surroundings, as well as changes in temperature, do not contribute to the coherent signal in the diffraction focus. Interference lithography or high-resolution-imaging lithography can be used to synthesize the coherent pattern of molecules on a monolithic substrate. The coherent pattern of molecules constitutes a synthetic phase hologram that creates a diffraction-limited light wave. We suggest the term "mologram" for the coherent assembly of functional nanostructures and the term "focal molography" for label-free or labeled analysis of molecular interactions through the measurement of the properties of light in the focus of the mologram. We derive analytical formulas that express the detection signal and the sensitivity of focal molography on the surface of a high-refractive-index thin-film optical waveguide in terms of known parameters. We discuss the implementation of a readout system for molograms on a thin-film optical waveguide by adapting a confocal laser-scanning microscope to a bifocal laser-scanning microscope.

Fattinger, Christof

2014-07-01

220

Optical coupling  

Microsoft Academic Search

This paper describes contributions to the CMBpol Technology Study Workshop concerning optical coupling structures. These are structures in or near the focal plane which convert the free space wave to a superconducting microstrip on a SI wafer, or to the waveguide input to a HEMT receiver. In addition to an introduction and conclusions by the editor, this paper includes independent

J. J. Bock; J. Gundersen; A. T. Lee; P. L. Richards; E. Wollack

2009-01-01

221

256 x 256 PACE-1 PV HgCdTe focal plane arrays for medium and short wavelength infrared applications  

NASA Technical Reports Server (NTRS)

The development of two 256 by 256 hybrid HgCdTe focal plane array (FPA) families is described, and their performance is discussed. The hybrid FPAs employ a PV HgCdTe detector array and custom Si CMOS readouts. The PACE-1 process was used to fabricate the detectors, whereby the liquid phase epitaxial growth of HgCdTe occurs on sapphire substrates buffered by a layer of CdTe. The performance characteristics of the detector arrays are given. A tactical 256 by 256 CMOS readout is tested, in which a high functional yield was achieved. Updated test results are given for a 256 by 256 readout circuit developed for use in an orbital replacement instrument for the Hubble Space Telescope. The characterizations of several MWIR and SWIR FPAs were thorough and shown to be reliable. The pixel yield, maximum FPA responsivity nonuniformity, and SWIR FPA read noise for the tests are given. The high contrast and insignificant fixed pattern noise of the imagery from the MWIR 256 by 256 FPA are emphasized. These qualities were obtained when the device was operating at 80 k and utilizing f/2 optics with an 8-in. focal length and a 4.4 micron high pass filter.

Kozlowski, L. J.; Vural, K.; Johnson, V. H.; Chen, J. K.; Bailey, R. B.

1990-01-01

222

Experimental Optics  

NASA Astrophysics Data System (ADS)

1. Elementary laws of optics; 2. Some applications of the laws of reflection and refraction; 3. Experiments with plane surfaces; 4. The spectrometer; 5. Experiments with prisms; 6. Spherical mirrors; 7. Thin lenses; 8. Experiments with thin lenses; 9. Coaxial optical systems - thick lenses; 10. Experiments with coaxial systems; 11. Astigmatism and focal lines; 12. Interference and polarisation by reflexion; 13. Diffraction grating and zone plate.

Searle, G. F. C.

2014-05-01

223

Characterization and simulation of optical sensors.  

PubMed

Numerical simulation is gradually becoming an advantage in active safety. This is why the development of realistic numerical models enabling to substitute real truth by simulated truth is primordial. In order to provide an accurate and cost effective solution to simulate real optical sensor behavior, the software Pro-SiVIC™ has been developed. Simulations with the software Pro-SiVIC™ can replace real tests with optical sensors and hence allow substantial cost and time savings during the development of solutions for driver assistance systems. An optical platform has been developed by IFSTTAR (French Institute of Science and Technology for Transport, Development and Networks) to characterize and validate any existing camera, in order to measure their characteristics as distortion, vignetting, focal length, etc. By comparing real and simulated sensors with this platform, this paper demonstrates that Pro-SiVIC™ accurately reproduces real sensors' behavior. PMID:23735581

Grapinet, M; De Souza, Ph; Smal, J-C; Blosseville, J-M

2013-11-01

224

4 Assessment 4.1 Focal Species  

E-print Network

not distinguish between shrubsteppe habitat dominated by introduced weed species and pristine shrubsteppe habitat29 4 Assessment 4.1 Focal Species A focal species will be used to evaluate the health for the wildlife assessment. Terrestrial/Wildlife: Because terrestrial wildlife species often are wide ranging

225

Hiperplasia nodular focal hepática y embarazo  

Microsoft Academic Search

Focal nodular hyperplasia of the liver in pregnancy may lead to doubts and inappropriate fears regarding the course of the pregnancy. There is a scarcity of literature addressing focal nodular hyperplasia during gestation, and there are even less data focused on delivery. We report the case of a pregnant woman previously diagnosed with an hepatic lesion and present a review

Clara Navarro Campoy; Francisco J. Morera Ocón; Enrique Tormos; Alfredo Perales Marín

2009-01-01

226

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

NASA Astrophysics Data System (ADS)

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.

Hinnrichs, Michele

2011-06-01

227

Early vision and focal attention  

NASA Astrophysics Data System (ADS)

At the thirty-year anniversary of the introduction of the technique of computer-generated random-dot stereograms and random-dot cinematograms into psychology, the impact of the technique on brain research and on the study of artificial intelligence is reviewed. The main finding-that stereoscopic depth perception (stereopsis), motion perception, and preattentive texture discrimination are basically bottom-up processes, which occur without the help of the top-down processes of cognition and semantic memory-greatly simplifies the study of these processes of early vision and permits the linking of human perception with monkey neurophysiology. Particularly interesting are the unexpected findings that stereopsis (assumed to be local) is a global process, while texture discrimination (assumed to be a global process, governed by statistics) is local, based on some conspicuous local features (textons). It is shown that the top-down process of "shape (depth) from shading" does not affect stereopsis, and some of the models of machine vision are evaluated. The asymmetry effect of human texture discrimination is discussed, together with recent nonlinear spatial filter models and a novel extension of the texton theory that can cope with the asymmetry problem. This didactic review attempts to introduce the physicist to the field of psychobiology and its problems-including metascientific problems of brain research, problems of scientific creativity, the state of artificial intelligence research (including connectionist neural networks) aimed at modeling brain activity, and the fundamental role of focal attention in mental events.

Julesz, Bela

1991-07-01

228

Pivoted document length normalization  

Microsoft Academic Search

Automatic information retrieval systems have to deal with documents of varying lengths in a text collection. Document length normalization is used to fairly retrieve documents of all lengths. In this study, we ohserve that a normalization scheme that retrieves documents of all lengths with similar chances as their likelihood of relevance will outperform another scheme which retrieves documents with chances

Amit Singhal; Chris Buckley; Manclar Mitra

1996-01-01

229

Measuring Crack Length in Coarse Grain Ceramics  

NASA Technical Reports Server (NTRS)

Due to a coarse grain structure, crack lengths in precracked spinel specimens could not be measured optically, so the crack lengths and fracture toughness were estimated by strain gage measurements. An expression was developed via finite element analysis to correlate the measured strain with crack length in four-point flexure. The fracture toughness estimated by the strain gaged samples and another standardized method were in agreement.

Salem, Jonathan A.; Ghosn, Louis J.

2010-01-01

230

Effect of device length and background doping on the relative magnitudes of phase and amplitude modulation in GaAs/AIGaAs PIN multiple quantum well waveguide optical modulators.  

PubMed

In this paper we present a model for the behavior of a PIN waveguide optical modulator utilizing the quantum confined Stark effect. The model uses experimental data to determine the electric field dependence of absorption coefficient and refractive index changes in 100-A GaAs/100-A Al(0.3)Ga(0.7)As quantum wells, and then uses these data to model a symmetric waveguide structure with a core full of quantum wells. We have determined general design rules for the background doping and length of low chirp amplitude modulators and phase modulators with low amplitude modulation. The chief results are that the doping should be high for an amplitude modulator and low for a phase modulator, and in both cases the device should be kept short. PMID:20548699

Bradley, P J; Whitehead, M; Parry, G; Mistry, P; Roberts, J S

1989-04-15

231

Design and development of the optics system for the NHXM Hard X-ray and Polarimetric Mission  

Microsoft Academic Search

The New Hard X-ray Mission (NHXM) Italian project will be operated by 2016. It is based on 4 hard X-ray optics modules, each formed by 60 evenly spaced multilayer coated Wolter I mirror shells. For the achievement of a long focal length (10 m) an extensible bench is used. The pseudo-cylindrical Wolter I monolithic substrates where the multilayer coating is

Giovanni Pareschi; Gianpiero Tagliaferri; Primo Attinà; Stefano Basso; Giuseppe Borghi; Oberto Citterio; Marta Civitani; Vincenzo Cotroneo; Barbara Negri; Giorgia Sironi; Daniele Spiga; Dervis Vernani; Giuseppe Valsecchi

2009-01-01

232

Focal plane resolution and overlapped array TDI imaging  

NASA Astrophysics Data System (ADS)

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.

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

2008-08-01

233

Multiplicative and subtractive focal volume engineering in coherent Raman microscopy  

PubMed Central

Rigorous calculations are performed to study the effective reduction of the nonlinear excitation volumes when using phase-only masks to condition the pump and Stokes driving fields. Focal volume reduction was achieved using both a multiplicative operation of the excitation fields as well as a subtractive operation. Using a tunable optical bottle beam for the Stokes field, an effective reduction of the width of the excitation volume by a factor of 1.5 can be achieved in the focal plane. Further reduction of the focal volume introduces a rapid growth of sidelobes, which renders such volumes unsuitable for imaging applications. In addition, phase sensitive detection was found to provide information from selective sub-divisions of the engineered coherent anti-Stokes Raman scattering excitation volume. In the case of isolated nanoparticles, an apparent resolution improvement by a factor of 3 is demonstrated, and it is shown that the size of sub-diffraction-limited particles can be accurately determined using phase sensitive detection. PMID:21045900

Raghunathan, Varun; Potma, Eric Olaf

2012-01-01

234

Third harmonic order imaging as a focal spot diagnostic for high intensity laser-solid interactions  

E-print Network

for near solid density interactions (plasma density scale length ,llaser, the laser wavelengthThird harmonic order imaging as a focal spot diagnostic for high intensity laser-solid interactions performance is laser spot size on a solid target during an intense interaction in the tight focus regime (,10

Strathclyde, University of

235

Optics for Athena  

NASA Astrophysics Data System (ADS)

The ATHENA mision will be based on a single X-ray telescope, with a focal length of 12m and an unprecedented effective area (2 m(2) at 1 keV), achieved by means of a single large diameter optics system that will host a very high number (up to 800) of mirror modules, each formed by 40 two-reflection segmented mirror shells.The inner and outer radiaii will be 250 mm and1500 mmrespectively.The requirement of the angular resolution is 5 arc seconds HEW, kept at the same level across a very wide field of view of 40-50 arcmin diameters. The X-ray telescope employs Silicon Pore Optics (SPO), an innovative technology that has been pioneered in Europe over the last decade mostly with ESA support. SPO is a highly modular concept, based on a set of compact individual mirror modules, which has an excellent effective area-to-mass ratio and can achieve high angular resolution. An alternative technology also ebvisage forsees the use of thin slumped glass mirrors. In this paper we will review the design, technology and develoment plan to address the ATHENA optics implementation.

Pareschi, Giovanni

236

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

PubMed

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

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

2014-10-10

237

Digital-pixel focal plane array development  

E-print Network

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 ...

Brown, Matthew G.

238

Focal Species and Representative Habitats Chuck Peven  

E-print Network

Focal Species and Representative Habitats Chuck Peven Peven Consulting, Inc. Wenatchee Subbasin in a theoretically sound and consistent manner to a known though low degree of accuracy (+/- 50%) has merit

239

Focal liver lesions: sinusoidal phase of CEUS  

Microsoft Academic Search

Ultrasound examination is the first imaging modality for hepatic study in neoplastic and chronic liver diseases. Focal liver\\u000a lesions frequently cause diagnostic problems in terms of characterization, especially when small and hypoechoic to the rest\\u000a of the parenchyma. Contrast- enhanced ultrasonography (CEUS) has shown its value in the characterization of focal liver lesions.\\u000a This study assessed the value of the

M. D’Onofrio; E. Martone; N. Faccioli; G. Zamboni; R. Pozzi Mucelli

2006-01-01

240

Design, fabrication and evaluation of chalcogenide glass Luneburg lenses for LiNbO3 integrated optical devices  

NASA Technical Reports Server (NTRS)

Optical waveguide Luneburg lenses of arsenic trisulfide glass are described. The lenses are formed by thermal evaporation of As2S3 through suitably placed masks onto the surface of LiNbO3:Ti indiffused waveguides. The lenses are designed for input apertures up to 1 cm and for speeds of f/5 or better. They are designed to focus the TM sub 0 guided mode of a beam of wavelength, external to the guide, of 633 nm. The refractive index of the As2S3 films and the changes induced in the refractive index by exposure to short wavelength light were measured. Some correlation between film thickness and optical properties was noted. The short wavelength photosensitivity was used to shorten the lens focal length from the as deposited value. Lenses of rectangular shape, as viewed from above the guide, as well as conventional circular Luneburg lenses, were made. Measurements made on the lenses include thickness profile, general optical quality, focal length, quality of focal spot, and effect of ultraviolet irradiation on optical properties.

Wood, V. E.; Busch, J. R.; Verber, C. M.

1982-01-01

241

Arc Length Gone Global  

ERIC Educational Resources Information Center

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…

Boudreaux, Gregory M.; Wells, M. Scott

2007-01-01

242

Three-element zoom lens with fixed distance between focal points.  

PubMed

This work deals with a theoretical analysis of zoom lenses with a fixed distance between focal points. Equations are derived for the primary (paraxial) design of the basic parameters of a three-element zoom lens. It is shown that the number of optical elements for such a lens must be larger than two. PMID:22739850

Mikš, Antonin; Novák, Ji?í; Novák, Pavel

2012-06-15

243

Phase singularities of the longitudinal field components in the focal region  

E-print Network

frequency is incident on the lens with the electric field polarized in the x direction. The notation that can be annihilated when the aperture angle of the lens is changed. © 2004 Optical Society of America in the focal region of such a system. For the case of a monochromatic, lin- early polarized plane wave

Visser, Taco D.

244

Curved-Focal-Plane Arrays Using Deformed-Membrane Photodetectors  

NASA Technical Reports Server (NTRS)

A versatile and simple approach to the design and fabrication of curved-focal-plane arrays of silicon-based photodetectors is being developed. This approach is an alternative to the one described in "Curved Focal-Plane Arrays Using Back- Illuminated High-Purity Photodetectors" (NPO-30566), NASA Tech Briefs, Vol. 27, No. 10 (October 2003), page 10a. As in the cited prior article, 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 (in this case, an array of photodetectors) conform to a curved focal surface, instead of designing the optics to project an image onto a flat focal surface. There is biological precedent for curved-focal-surface designs: retinas - the image sensors in eyes - conform to the naturally curved focal surfaces of eye lenses. The present approach is applicable to both front-side- and back-side-illuminated, membrane photodetector arrays and is being demonstrated on charge-coupled devices (CCDs). The very-large scale integrated (VLSI) circuitry of such a CCD or other array is fabricated on the front side of a silicon substrate, then the CCD substrate is attached temporarily to a second substrate for mechanical support, then material is removed from the back to obtain the CCD membrane, which typically has a thickness between 10 and 20 m. In the case of a CCD designed to operate in back-surface illumination, delta doping can be performed after thinning to enhance the sensitivity. This approach is independent of the design and method of fabrication of the front-side VLSI circuitry and does not involve any processing of a curved silicon substrate. In this approach, a third substrate would be prepared by polishing one of its surfaces to a required focal-surface curvature. A CCD membrane fabricated as described above would be pressed against, deformed into conformity with, and bonded to, the curved surface. The technique used to press and bond the CCD membrane would depend on the nature of the supporting material (see figure). For example, if the third substrate were made of quartz frit, the substrate would be prepared by suffusing it with epoxy. Then one would take advantage of the porosity of the frit by applying a partial vacuum to the opposite surface of the frit, causing atmospheric pressure to push the CCD membrane against the curved surface. The curing of the epoxy would bond the CCD membrane to the curved surface. Alternatively, if the third substrate were made of a nonporous material, the curved substrate surface would be prepared by coating it with a wax or an uncured epoxy. The CCD membrane would be pressed against the coated, curved surface by use of a suitably pressurized balloon. The CCD membrane would then become bonded to the curved surface by curing of the epoxy or freezing of the wax.

Nikzad, Shouleh; Jones, Todd

2004-01-01

245

DIVA optical telescope  

NASA Astrophysics Data System (ADS)

The German Instrument for Multi-channel Photometry and Astrometry (DIVA), dedicated to the German (DLR) small extraterrestrial satellite program, is intended as a kind of technology precursor mission to GAIA. DIVA is scheduled for launch in 2004 and shall perform a sky survey to measure within 2 years life time the positions, parallaxes, magnitudes, etc. of about 35 million stars. The main instrument, covering the spectral range of 400-1000nm, observes 2 fields of view (0.6° x 0.77°) by a single Focal Plane Assembly (FPA). The focal length is 11200mm. The DIVA Optomechanics is based on a high precision Three Mirror Anastigmat (TMA) concept with 8 mirrors, 5 of them flat. An extremely high short term stability (torsion tolerance) of 0.3 mas over 10h only has to be realized only by passive means to achieve the astrometrical performance requirements. The paper describes the phase B2 design activities wrt. the optomechanical and thermal design of the main instrument. Special emphasis is given to an exhausting, but very pragmatic thermomechanical and optical performance trade off between a cost effective athermal design concept, applying mirrors and an optical bench made from a specially treated isotropic aluminum alloy, and a thermally stable hybrid material concept based on a Carbon Fiber Reinforced Plastics (CFRP) sandwich structure and Zerodur mirrors. The selection of the final baseline design solution shall be reported. According to the very high long and short scale surface properties of the candidate aluminum mirrors a sophisticated manufacturing procedure was established based on conventional and ion beam polishing techniques. The representative breadboard mirror test results will be given.

Graue, Roland; Kampf, Dirk; Röser, Siegfried; Bastian, Ulrich; Seifert, Walter

2003-02-01

246

Hand-held optical fuel pin scanner  

DOEpatents

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.

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

1980-12-07

247

Hand-held optical fuel pin scanner  

DOEpatents

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.

Kirchner, Tommy L. (Richland, WA); Powers, Hurshal G. (Richland, WA)

1987-01-01

248

Measuring Thermodynamic Length  

SciTech Connect

Thermodynamic length is a metric distance between equilibrium thermodynamic states. Among other interesting properties, this metric asymptotically bounds the dissipation induced by a finite time transformation of a thermodynamic system. It is also connected to the Jensen-Shannon divergence, Fisher information, and Rao's entropy differential metric. Therefore, thermodynamic length is of central interestin understanding matter out of equilibrium. In this Letter, we will consider how to denethermodynamic length for a small system described by equilibrium statistical mechanics and how to measure thermodynamic length within a computer simulation. Surprisingly, Bennett's classic acceptance ratio method for measuring free energy differences also measures thermodynamic length.

Crooks, Gavin E

2007-09-07

249

The design and evaluation of grazing incidence relay optics  

NASA Technical Reports Server (NTRS)

X-ray astronomy, both solar and celestial, has many needs for high spatial resolution observations which have to be performed with electronic detectors. If the resolution is not to be detector limited, plate scales in excess of 25 microns arc/sec, corresponding to focal lengths greater than 5 m, are required. In situations where the physical size is restricted, the problem can be solved by the use of grazing incidence relay optics. A system was developed which employs externally polished hyperboloid-hyperboloid surfaces to be used in conjunction with a Wolter-Schwarzschild primary. The secondary is located in front of the primary focus and provides a magnification of 4, while the system has a plate scale of 28 microns arc/sec and a length of 1.9 m. The design, tolerance specification, fabrication and performance at visible and X-ray wavelengths of this optical system are described.

Davis, John M.; Chase, R. C.; Silk, J. K.; Krieger, A. S.

1989-01-01

250

Axial separation of orthogonally polarized focal field components due to a radially polarized beam.  

PubMed

In this paper, we investigate the field distribution in the focal volume of an aberrated radially polarized beam. Using two different forms of the vectorial diffraction theory, we show that the presence of defocus in the beam displaces both the axially and the radially polarized fields parallel to the optical axis of the focusing lens, while the presence of spherical aberration primarily shifts the longitudinally polarized field only. This facilitates axial separation of the two orthogonally polarized field components, resulting in a significant boost to the ratio of the peak longitudinally polarized field to the peak laterally polarized field in the focal plane. We further show that with an appropriate combination of oppositely signed defocus and spherical aberration, the energy density in the focal volume due to the longitudinally polarized field can be caused to peak at the focal plane. The results obtained are expected to be beneficial to the applications requiring a stronger longitudinally polarized focal field relative to the laterally polarized focal field component. PMID:22751392

Boruah, Bosanta R

2012-07-01

251

Modeling a variable-focus liquid-filled optical lens  

NASA Astrophysics Data System (ADS)

Research has been conducted on a variable-focus liquid-filled optical lens built from a polymer elastic-film window and a rigid plastic window with a transparent refractive liquid between these windows. The pressure inside the lens deforms the elastic film, which takes the form of a paraboloid. The absolute value of the tension in the film was calculated, allowing theoretical evaluation of the focal length of the lens and its aberrations. The developed mathematical model of the liquid-filled flexible lens agrees well with experimental results.

Rawicz, Andrew H.; Mikhailenko, Iouri

1996-04-01

252

Transparent Meta-Analysis: Does Aging Spare Prospective Memory with Focal vs. Non-Focal Cues?  

PubMed Central

Background Prospective memory (ProM) is the ability to become aware of a previously-formed plan at the right time and place. For over twenty years, researchers have been debating whether prospective memory declines with aging or whether it is spared by aging and, most recently, whether aging spares prospective memory with focal vs. non-focal cues. Two recent meta-analyses examining these claims did not include all relevant studies and ignored prevalent ceiling effects, age confounds, and did not distinguish between prospective memory subdomains (e.g., ProM proper, vigilance, habitual ProM) (see Uttl, 2008, PLoS ONE). The present meta-analysis focuses on the following questions: Does prospective memory decline with aging? Does prospective memory with focal vs. non-focal cues decline with aging? Does the size of age-related declines with focal vs. non-focal cues vary across ProM subdomains? And are age-related declines in ProM smaller than age-related declines in retrospective memory? Methods and Findings A meta-analysis of event-cued ProM using data visualization and modeling, robust count methods, and conventional meta-analysis techniques revealed that first, the size of age-related declines in ProM with both focal and non-focal cues are large. Second, age-related declines in ProM with focal cues are larger in ProM proper and smaller in vigilance. Third, age-related declines in ProM proper with focal cues are as large as age-related declines in recall measures of retrospective memory. Conclusions The results are consistent with Craik's (1983) proposal that age-related declines on ProM tasks are generally large, support the distinction between ProM proper vs. vigilance, and directly contradict widespread claims that ProM, with or without focal cues, is spared by aging. PMID:21304905

Uttl, Bob

2011-01-01

253

Gauss-Legendre quadrature method used to evaluate the electric field envelope of ultrashort pulses in the focal region of lenses  

NASA Astrophysics Data System (ADS)

We analyze the Gaussian temporal envelope of pulses with an initial duration of 10fs and a carrier wavelength of 810nm along the optical axis of an achromatic doublet designed in the IR region with numerical aperture 0.15 and focal length of 40mm. The diffraction integral is solved by expanding the wave number around the carrier frequency of the pulse in a Taylor series up to third order, and then the integral over the frequencies is solved by using the Gauss-Legendre quadrature method. The numerical errors in this method are negligible by taking 96 nodes and the computational time is reduced by 95% compared to the integration method by rectangles. We will show that the third-order GVD is not negligible for 10fs pulses @810nm propagating through the low numerical aperture doublet and its effect is more important than the propagation time difference, PTD. This last effect, however, is also significant.

García-Martínez, L.; Rosete-Aguilar, M.; Garduño-Mejía, J.

2011-09-01

254

Gaze Movement & Focal Points Perceptual and Artistic Principles for  

E-print Network

" our vision while the gaze moves Gaze Movement & Focal Points Saccadic exploration · Reading: Javal Advertisement and focal points · Evolution of saliency Gaze Movement & Focal Points Further reading VisionGaze Movement & Focal Points Perceptual and Artistic Principles for Effective Computer Depiction

Durand, Frédo

255

Earthquake Focal Mechanisms Imply Homogeneous Stress at Seismogenic Depths  

Microsoft Academic Search

Stress at seismogenic depths is often thought to be heterogeneous, based on the variety of earthquake focal mechanisms present in some catalogs, particularly southern California. However, when differences in tectonic regime and the sizable focal mechanism uncertainties are accounted for, the southern California focal mechanisms appear more uniform. Analysis of several focal mechanism catalogs demonstrates that on average, the closer

J. L. Hardebeck

2010-01-01

256

Optical fuel pin scanner  

DOEpatents

An optical scanner for indicia arranged in a focal plane at a cylindrical outside surface by use of an optical system including a rotatable dove prism. The dove prism transmits a rotating image of an encircled cylindrical surface area to a stationary photodiode array.

Kirchner, Tommy L. (Richland, WA); Powers, Hurshal G. (Richland, WA)

1983-01-01

257

Document Length Normalization  

Microsoft Academic Search

In the TREC collection—a large full-text experimental text collection with widely varying document lengths—we observe that the likelihood of a document being judged relevant by a user increases with the document length. We show that a retrieval strategy, such as the vector-space cosine match, that retrieves documents of different lengths with roughly equal chances, will not optimally retrieve useful documents

Amit Singhal; Gerard Salton; Mandar Mitra; Chris Buckley

1996-01-01

258

Acousto-optically cavity dumped Tm:YAG laser with 54 ns pulses at 200 kHz repetition rate.  

PubMed

In this paper, a cavity dumped Tm:YAG laser was obtained for the first time, whose output pulse width was constant at 54 ns. Maximum repetition rate was 200 kHz, and wavelength was 2013 nm. Its average output power was 595 mW. The laser cavity length was 208 mm with an inserted acousto-optic modulator. Pulses were coupled out of the lateral surface of the cavity when Radio Frequency was added into the modulator. And lens was used to compensate the thermal focal length of Tm:YAG crystal. Numerical calculation of pulse was done. PMID:24787876

Cai, Guoqing; Ju, Youlun; Yao, Baoquan; Liu, Wei; Duan, Xiaoming; Dai, Tongyu

2014-04-21

259

Thrombospondin modulates focal adhesions in endothelial cells  

PubMed Central

We examined the effects of thrombospondin (TSP) in the substrate adhesion of bovine aortic endothelial cells. The protein was tested both as a substrate for cell adhesion and as a modulator of the later stages of the cell adhesive process. TSP substrates supported the attachment of some BAE cells, but not cell spreading or the formation of focal adhesion plaques. In contrast, cells seeded on fibrinogen or fibronectin substrates were able to complete the adhesive process, as indicated by the formation of focal adhesion plaques. Incubation of cells in suspension with soluble TSP before or at the time of seeding onto fibronectin substrates resulted in an inhibition of focal adhesion formation. Furthermore, the addition of TSP to fully adherent cells in situ or prespread on fibronectin substrates caused a reduction in the number of cells, which were positive for focal adhesions, although there was no significant effect on cell spreading. In a dose-dependent manner, TSP reduced the number of cells with adhesion plaques to approximately 60% of control levels. The distribution of remaining adhesion plaques in TSP-treated cells was also altered: plaques were primarily limited to the periphery of cells and were not present in the central cell body, as in control cells treated with BSA. The observed effects were specific for TSP and were not observed with platelet factor 4, beta-thromboglobulin, or fibronectin. The TSP-mediated loss of adhesion plaques was neutralized by the addition of heparin, fucoidan, other heparin-binding proteins, and by a monoclonal antibody to the heparin binding domain of TSP, but not by antibodies to the core or carboxy-terminal regions of TSP. The interaction of the heparin- binding domain of TSP with cell-associated heparan sulfate appears to be an important mechanistic component for this activity of TSP. These data indicate that TSP may have a role in destabilizing cell adhesion through prevention of focal adhesion formation and by loss of preformed focal adhesions. PMID:2768342

1989-01-01

260

The Statistics of Calcium-Mediated Focal Excitations on a One-Dimensional Cable  

PubMed Central

It is well known that various cardiac arrhythmias are initiated by an ill-timed excitation that originates from a focal region of the heart. However, up to now, it is not known what governs the timing, location, and morphology of these focal excitations. Recent studies have shown that these excitations can be caused by abnormalities in the calcium (Ca) cycling system. However, the cause-and-effect relationships linking subcellular Ca dynamics and focal activity in cardiac tissue is not completely understood. In this article, we present a minimal model of Ca-mediated focal excitations in cardiac tissue. This model accounts for the stochastic nature of spontaneous Ca release on a one-dimensional cable of cardiac cells. Using this model, we show that the timing of focal excitations is equivalent to a first passage time problem in a spatially extended system. In particular, we find that for a short cable the mean first passage time increases exponentially with the number of cells in tissue, and is critically dependent on the ratio of inward to outward currents near the threshold for an action potential. For long cables excitations occurs due to ectopic foci that occur on a length scale determined by the minimum length of tissue that can induce an action potential. Furthermore, we find that for long cables the mean first passage time decreases as a power law in the number cells. These results provide precise criteria for the occurrence of focal excitations in cardiac tissue, and will serve as a guide to determine the propensity of Ca-mediated triggered arrhythmias in the heart. PMID:22325268

Chen, Wei; Asfaw, Mesfin; Shiferaw, Yohannes

2012-01-01

261

Focal plane array for the GERB instrument  

NASA Astrophysics Data System (ADS)

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.

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

2004-02-01

262

Snake beam: a paraxial arbitrary focal line  

NASA Astrophysics Data System (ADS)

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.

Rosen, Joseph; Yariv, Amnon

1995-10-01

263

Ambroxol-induced focal epileptic seizure.  

PubMed

It is well known that in epileptic patients some compounds and different drugs used for the treatment of comorbidities can facilitate or provoke seizures, this evidence regarding a wide spectrum of pharmacological categories. The potential facilitating factors usually include direct toxic effects or pharmacological interactions of either active ingredients or excipients. We report the case of a patient with drug-resistant epilepsy who experienced focal epileptic seizures, easily and constantly reproducible, after each administration of a cough syrup. This is, to our knowledge, the first electroencephalogram-documented case of focal epileptic seizures induced by cough syrup containing ambroxol as active ingredient. PMID:24824664

Lapenta, Leonardo; Morano, Alessandra; Fattouch, Jinane; Casciato, Sara; Fanella, Martina; Giallonardo, Anna Teresa; Di Bonaventura, Carlo

2014-01-01

264

Kalman Filter for Calibrating a Telescope Focal Plane  

NASA Technical Reports Server (NTRS)

The instrument-pointing frame (IPF) Kalman filter, and an algorithm that implements this filter, have been devised for calibrating the focal plane of a telescope. As used here, calibration signifies, more specifically, a combination of measurements and calculations directed toward ensuring accuracy in aiming the telescope and determining the locations of objects imaged in various arrays of photodetectors in instruments located on the focal plane. The IPF Kalman filter was originally intended for application to a spaceborne infrared astronomical telescope, but can also be applied to other spaceborne and ground-based telescopes. In the traditional approach to calibration of a telescope, (1) one team of experts concentrates on estimating parameters (e.g., pointing alignments and gyroscope drifts) that are classified as being of primarily an engineering nature, (2) another team of experts concentrates on estimating calibration parameters (e.g., plate scales and optical distortions) that are classified as being primarily of a scientific nature, and (3) the two teams repeatedly exchange data in an iterative process in which each team refines its estimates with the help of the data provided by the other team. This iterative process is inefficient and uneconomical because it is time-consuming and entails the maintenance of two survey teams and the development of computer programs specific to the requirements of each team. Moreover, theoretical analysis reveals that the engineering/ science iterative approach is not optimal in that it does not yield the best estimates of focal-plane parameters and, depending on the application, may not even enable convergence toward a set of estimates.

Kang, Bryan; Bayard, David

2006-01-01

265

Neandertal clavicle length  

PubMed Central

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

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

2014-01-01

266

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

PubMed Central

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

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

2011-01-01

267

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

E-print Network

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

Bartoli, Adrien

268

2D focal-field aberration dependence on time\\/phase screen position and correlation lengths  

Microsoft Academic Search

For high-frequency annular array transducers used in medical ultrasound imaging, aberrations due to tissue and body wall have a significant effect on energy transfer from the main lobe to the sidelobes of the acoustic field: that is, the aberrations make the total sidelobe level increase. This effect makes the ultrasound image poor when imaging heterogeneous organs. This study performs an

Sven Peter Näsholm

2001-01-01

269

An Integrated Optimal Estimation Approach to Spitzer Space Telescope Focal Plane Survey  

NASA Technical Reports Server (NTRS)

This paper discusses an accurate and efficient method for focal plane survey that was used for the Spitzer Space Telescope. The approach is based on using a high-order 37-state Instrument Pointing Frame (IPF) Kalman filter that combines both engineering parameters and science parameters into a single filter formulation. In this approach, engineering parameters such as pointing alignments, thermomechanical drift and gyro drifts are estimated along with science parameters such as plate scales and optical distortions. This integrated approach has many advantages compared to estimating the engineering and science parameters separately. The resulting focal plane survey approach is applicable to a diverse range of science instruments such as imaging cameras, spectroscopy slits, and scanning-type arrays alike. The paper will summarize results from applying the IPF Kalman Filter to calibrating the Spitzer Space Telescope focal plane, containing the MIPS, IRAC, and the IRS science Instrument arrays.

Bayard, David S.; Kang, Bryan H.; Brugarolas, Paul B.; Boussalis, D.

2004-01-01

270

Focal myasthenia gravis in a dog.  

PubMed Central

A 10-month-old American cocker spaniel was evaluated for megaesophagus, aspiration pneumonia, but no appendicular muscle weakness. During hospitalization, weakness of the facial muscles developed, this resolved with anticholinesterase administration. Serum antibodies against acetylcholine receptors were documented, confirming the diagnosis of focal myasthenia gravis. Diagnosis, management, and medical treatment are discussed. Images Figure 1. Figure 2. PMID:9262858

Webb, A A; Taylor, S M; McPhee, L

1997-01-01

271

Pragmatic Epistemology of Focal Teacher Thinking.  

ERIC Educational Resources Information Center

Pragmatic epistemology of focal teacher thinking appears tightly shaped by modular connections between task domains and pragmatic organizers. Discussions with a group of language teachers identified four domains of tasks: (1) oral activities; (2) writing activities; (3) reading activities; and (4) language technique activities (grammar, spelling).…

Tochon, Francois V.

272

Vasoconstrictive neurovascular coupling during focal ischemic depolarizations  

E-print Network

Vasoconstrictive neurovascular coupling during focal ischemic depolarizations Hwa Kyoung Shin1 , Andrew K Dunn2 , Phillip B Jones2 , David A Boas2 , Michael A Moskowitz1 and Cenk Ayata1,3 1 Stroke, Massachusetts, USA; 2 Department of Radiology, Martinos Center for Biomedical Imaging, Massachusetts General

Boas, David

273

Considerations for patient selection for focal therapy  

PubMed Central

Focal therapy for prostate cancer is a nascent and emerging field. As such, the patient selection criteria for this new treatment paradigm are evolving in parallel to both the technology on which this approach depends and to our unfolding understanding of the natural history of prostate cancer. Until, and while, prospective trials of focal therapy are being reported, patient selection criteria will be flexible and very dependent on the therapeutic goals. We must carefully define the therapeutic intentions of focal therapy before engaging in the actual process of determining optimal patient selection. The therapeutic intent will define the most appropriate candidate for such therapy. Patient selection encompasses multiple complex issues including the type of prostate biopsy (12 core transrectal versus mapping transperineal) to the type of imaging (multiparametric magnetic resonance imaging or enhanced ultrasound) to the specific anatomical location of the disease within the prostate (apex, mid-prostate, base) and a comprehensive assessment of the patient’s overall health and life expectancy. It is not as simple as saying a patient with a certain grade or a certain number of cores is or is not appropriate for focal therapy. There are many more considerations for a reasonable and thoughtful approach to this new treatment. PMID:24294291

Pisters, Louis L.

2013-01-01

274

Rifampicin attenuates brain damage in focal ischemia  

Microsoft Academic Search

Rifampicin is an antibacterial agent that is widely used in tuberculosis and leprosy therapy. Interestingly, some experimental studies indicate that rifampicin acts as a hydroxyl radical scavenger and a glucocorticoid receptor activator. In this study, the neuroprotective effect of rifampicin was evaluated after transient and permanent focal cerebral ischemia. Anaesthetized male C57BL\\/6j mice were submitted to permanent or transient thread

Burak Yulug; Ülkan Kilic; Ertugrul Kilic; Mathias Bähr

2004-01-01

275

Calculation of the illuminance distribution in the focal spot of a focusing system taking into account aberrations in this system and divergence of a focused laser beam  

SciTech Connect

The dependence of the focal-spot size of a 'deep' parabolic mirror reflector on the laser-beam divergence is analysed by the method of elementary reflections. The dependence of the focal-beam diameter of an ideal focusing optical system on the laser-beam parameters is described. The expression is obtained for calculating the illumination distribution in the focal spot of a 'deep' mirror reflector which takes into account both aberrations and light-gathering power of the reflector and the divergence of a focused laser beam. (optical systems)

Gitin, Andrey V [Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspectroskopie, Berlin (Germany)

2007-03-31

276

GR Proper Length Program  

NSDL National Science Digital Library

The GR Proper Length program simulates the distance between points using the Schwarzschild metric. It displays the proper length between two points and the light-travel path. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the gr_properlength.jar file will run the program if Java is installed. GR Proper Length is part of a suite of Open Source Physics programs that model aspects of General Relativity. Other programs provide additional visualizations. They can be found by searching ComPADRE for Open Source Physics, OSP, or General Relativity.

Christian, Wolfgang; Belloni, Mario; Cox, Anne

2008-05-14

277

Hepatic adenoma and focal nodular hyperplasia.  

PubMed

Hepatic adenoma and focal nodular hyperplasia are benign lesions of the liver. The incidence of these conditions has been increasing since 1970. Hepatic adenoma primarily affects young women of childbearing age who have a long history of using oral contraceptives, while focal nodular hyperplasia has a wider age distribution and is not associated with the use of oral contraceptives. The most extensive complication of hepatic adenoma is intratumoral or intraperitoneal hemorrhage, which occurs in 50 to 60 per cent of patients. Patients with focal nodular hyperplasia are usually asymptomatic and rarely experience complications. Hepatic adenoma is distinct from focal nodular hyperplasia both in its clinical behavior and its pathologic features; the two can usually be differentiated radiographically using a combination of radionuclide scanning and angiography. There is a proved association between the use of oral contraceptives and the development of hepatic adenoma; the longer the duration of oral contraceptive use, the more the risk of having hepatic adenoma develop. In addition, users of oral contraceptives who have hepatic adenoma develop are likely to have larger tumors and higher rates of bleeding and rupture than nonusers who have hepatic adenoma develop. Although hepatic adenomas may regress after discontinuation of oral contraceptive use, this is not a consistent finding. In addition, it has now been demonstrated that hepatic adenomas do undergo malignant transformation and that this can be detected by measuring the alpha-fetoprotein level. Focal nodular hyperplasia may be a precursor for fibrolamellar hepatocellular carcinoma. Elective resection of hepatic adenoma has a mortality rate of less than 1 per cent, while the mortality rate with free rupture is 5 to 10 per cent. Because of the relative safety of elective versus emergency resection and the potential for malignant change, the treatment of choice for hepatic adenoma is surgical resection. PMID:1658955

Shortell, C K; Schwartz, S I

1991-11-01

278

The focal-plane instruments on board WSO-UV  

E-print Network

Dedicated to spectroscopic and imaging observations of the ultraviolet sky, the World Space Observatory for Ultraviolet Project is a Russia led international collaboration presently involving also China, Germany, Italy, Spain and Ukraine. The mission consists of a 1.7m telescope able to perform: a) high resolution (R greater than 60000) spectroscopy by means of two echelle spectrographs covering the 103-310 nm range; b) long slit (1x75 arcsec) low resolution (R about 1500-2500) spectroscopy using a near-UV channel and a far-UV channel to cover the 102-310nm range; c) deep UV and diffraction limited UV and optical imaging (from 115 to 700 nm). Overall information on the project and on its science objectives are given by other two papers in these proceedings. Here we present the WSO-UV focal plane instruments, their status of implementation, and the expected performances.

I. Pagano; M. Sachkov; A. I. Gomez de Castro; M. Huang; N. Kappelmann; S. Scuderi; B. Shustov; K. Werner; G. Zhao

2008-01-14

279

The focal-plane instruments on board WSO-UV  

E-print Network

Dedicated to spectroscopic and imaging observations of the ultraviolet sky, the World Space Observatory for Ultraviolet Project is a Russia led international collaboration presently involving also China, Germany, Italy, Spain and Ukraine. The mission consists of a 1.7m telescope able to perform: a) high resolution (R greater than 60000) spectroscopy by means of two echelle spectrographs covering the 103-310 nm range; b) long slit (1x75 arcsec) low resolution (R about 1500-2500) spectroscopy using a near-UV channel and a far-UV channel to cover the 102-310nm range; c) deep UV and diffraction limited UV and optical imaging (from 115 to 700 nm). Overall information on the project and on its science objectives are given by other two papers in these proceedings. Here we present the WSO-UV focal plane instruments, their status of implementation, and the expected performances.

Pagano, I; de Castro, A I Gomez; Huang, M; Kappelmann, N; Scuderi, S; Shustov, B; Werner, K; Zhao, G

2008-01-01

280

A new staring 94-GHz focal plane array  

NASA Astrophysics Data System (ADS)

A new staring 94 GHz focal plane array (4x8 pixels) multi-chip module (MCM) using a quasi-optically pumped MMIC gate mixer is presented. The new MCM with integrated microstrip antennas, matching and bias networks are manufactured using a modified MCM-D process based on 3x15 ?m BCB. The active gate mixer MMIC was manufactured by OMMIC (D01PH process) and uses a 2x25 ?m gate width. The 30 cm dielectric lens antenna has a F/D number of approximately unity. To minimize the spillover loss, the beamwidth of the feed antennas (microstrip antennas) was matched to the opening angle of the lens by using 2x2 subarrays for each pixel. Preliminary measurement results show a feed antenna gain of approximately 10 dBi and a conversion loss close to zero at 94 GHz, and an optimal pumping power of -2 dBm at 92.4 GHz.

Svedin, Jan; Huss, Lars-Gunnar

2004-12-01

281

Myofilament length dependent activation  

SciTech Connect

The Frank-Starling law of the heart describes the interrelationship between end-diastolic volume and cardiac ejection volume, a regulatory system that operates on a beat-to-beat basis. The main cellular mechanism that underlies this phenomenon is an increase in the responsiveness of cardiac myofilaments to activating Ca{sup 2+} ions at a longer sarcomere length, commonly referred to as myofilament length-dependent activation. This review focuses on what molecular mechanisms may underlie myofilament length dependency. Specifically, the roles of inter-filament spacing, thick and thin filament based regulation, as well as sarcomeric regulatory proteins are discussed. Although the 'Frank-Starling law of the heart' constitutes a fundamental cardiac property that has been appreciated for well over a century, it is still not known in muscle how the contractile apparatus transduces the information concerning sarcomere length to modulate ventricular pressure development.

de Tombe, Pieter P.; Mateja, Ryan D.; Tachampa, Kittipong; Mou, Younss Ait; Farman, Gerrie P.; Irving, Thomas C. (IIT); (Loyola)

2010-05-25

282

Myofilament Length Dependent Activation  

PubMed Central

The Frank-Starling law of the heart describes the interrelationship between end-diastolic volume and cardiac ejection volume, a regulatory system that operates on a beat-to-beat basis. The main cellular mechanism that underlies this phenomenon is an increase in the responsiveness of cardiac myofilaments to activating Ca2+ ions at a longer sarcomere length, commonly referred to as myofilament length dependent activation. This review focuses on what molecular mechanisms may underlie myofilament length dependency. Specifically, the roles of inter-filament spacing, thick and thin filament based regulation, as well as sarcomeric regulatory proteins are discussed. Although the “Frank-Starling law of the heart” constitutes a fundamental cardiac property that has been appreciated for well over a century, it is still not known in muscle how the contractile apparatus transduces the information concerning sarcomere length to modulate ventricular pressure development. PMID:20053351

de Tombe, Pieter P.; Mateja, Ryan D.; Kittipong-Tachampa; Mou, Younss Ait; Farman, Gerrie P.; Irving, Thomas C.

2010-01-01

283

Lengths of Ladybugs  

NSDL National Science Digital Library

This lesson plan for teachers of kindergarten students involves activities that introduce the concepts of using a non-standard unit to measure length and associating a measurement with a number. After introducing the lesson with a literature connection, students cut out their own measuring cards and use them to compare lengths, and measure distance along a path using a line of ladybug beans and a non-standard tape. Materials, handouts, and suggestions for extensions and parental involvement are included.

Lessonplans, Utah

2006-06-24

284

Development of microchannel plate x-ray optics  

NASA Technical Reports Server (NTRS)

The goal of this research program was to develop a novel technique for focusing x-rays based on the optical system of a lobster's eye. A lobster eye employs many closely packed reflecting surfaces arranged within a spherical or cylindrical shell. These optics have two unique properties: they have unlimited fields of view and can be manufactured via replication of identical structures. Because the angular resolution is given by the ratio of the size of the individual optical elements to the focal length, optical elements with size on the order of one hundred microns are required to achieve good angular resolution with a compact telescope. We employed anisotropic etching of single crystal silicon wafers for the fabrication of micron-scale optical elements. This technique, commonly referred to as silicon micromachining, is based on silicon fabrication techniques developed by the microelectronics industry. We have succeeded in producing silicon lenses with a geometry suitable for a 1-d focusing x-ray optics. These lenses have an aspect ratio (40:1) suitable for x-ray reflection and have very good optical surface alignment. We have developed a number of process refinements which improved the quality of the lens geometry and the repeatability of the etch process. In addition to the silicon fabrication, an x-ray beam line was constructed at Columbia for testing the optics. Most recently, we have done several experiments to find the fundamental limits that the anisotropic etch process placed on the etched surface roughness.

Kaaret, Philip

1995-01-01

285

Editorial: Redefining Length  

SciTech Connect

Technological changes have moved publishing to electronic-first publication where the print version has been relegated to simply another display mode. Distribution in HTML and EPUB formats, for example, changes the reading environment and reduces the need for strict pagination. Therefore, in an effort to streamline the calculation of length, the APS journals will no longer use the printed page as the determining factor for length. Instead the journals will now use word counts (or word equivalents for tables, figures, and equations) to establish length; for details please see http://publish.aps.org/authors/length-guide. The title, byline, abstract, acknowledgment, and references will not be included in these counts allowing authors the freedom to appropriately credit coworkers, funding sources, and the previous literature, bringing all relevant references to the attention of readers. This new method for determining length will be easier for authors to calculate in advance, and lead to fewer length-associated revisions in proof, yet still retain the quality of concise communication that is a virtue of short papers.

Sprouse, Gene D. [American Physical Society (United States)

2011-07-15

286

Eigenfunction expansion of the electric fields in the focal region of a high numerical aperture focusing system.  

PubMed

The Debye-Wolf electromagnetic diffraction integral is now routinely used to describe focusing by high numerical (NA) lenses. We obtain an eigenfunction expansion of the electric vector field in the focal region in terms of Bessel and generalized prolate spheroidal functions. Our representation has many optimal and desirable properties which offer considerable simplification to the evaluation and analysis of the Debye- Wolf integral. It is potentially also useful in implementing two-dimensional apodization techniques to synthesize electromagnetic field distributions in the focal region of a high NA lenses. Our work is applicable to many areas, such as optical microscopy, optical data storage and lithography. PMID:18542431

Sherif, Sherif S; Foreman, Matthew R; Török, Peter

2008-03-01

287

Progress in long scale length laser plasma interactions  

Microsoft Academic Search

The first experiments on the National Ignition Facility (NIF) have employed the first four beams to measure propagation and laser backscattering losses in large ignition-size plasmas. Gas-filled targets between 2 and 7 mm length have been heated from one side by overlapping the focal spots of the four beams from one quad operated at 351 nm (3omega) with a total

S. H. Glenzer; P. Arnold; G. Bardsley; R. L. Berger; G. Bonanno; T. Borger; D. E. Bower; M. Bowers; R. Bryant; S. Buckman; S. C. Burkhart; K. Campbell; M. P. Chrisp; B. I. Cohen; C. Constantin; F. Cooper; J. Cox; E. Dewald; L. Divol; S. Dixit; J. Duncan; D. Eder; J. Edwards; G. Erbert; B. Felker; J. Fornes; G. Frieders; D. H. Froula; S. D. Gardner; C. Gates; M. Gonzalez; S. Grace; G. Gregori; A. Greenwood; R. Griffith; T. Hall; B. A. Hammel; C. Haynam; G. Heestand; M. Henesian; G. Hermes; D. Hinkel; J. Holder; F. Holdner; G. Holtmeier; W. Hsing; S. Huber; T. James; S. Johnson; O. S. Jones; D. Kalantar; J. H. Kamperschroer; R. Kauffman; T. Kelleher; J. Knight; R. K. Kirkwood; W. L. Kruer; W. Labiak; O. L. Landen; A. B. Langdon; S. Langer; D. Latray; A. Lee; F. D. Lee; D. Lund; B. MacGowan; S. Marshall; J. McBride; T. McCarville; L. McGrew; A. J. Mackinnon; S. Mahavandi; K. Manes; C. Marshall; J. Menapace; E. Mertens; N. Meezan; G. Miller; S. Montelongo; J. D. Moody; E. Moses; D. Munro; J. Neumann; M. Newton; E. Ng; C. Niemann; A. Nikitin; P. Opsahl; E. Padilla; T. Parham; G. Parrish; C. Petty; M. Polk; C. Powell; I. Reinbachs; V. Rekow; R. Rinnert; B. Riordan; M. Rhodes; V. Roberts; H. Robey; G. Ross; S. Sailors; R. Saunders; M. Schmitt; M. B. Schneider; S. Shiromizu; M. Spaeth; A. Stephens; B. Still; L. J. Suter; G. Tietbohl; M. Tobin; J. Tuck; B. M. Van Wonterghem; R. Vidal; D. Voloshin; R. Wallace; P. Wegner; P. Whitman; E. A. Williams; K. Williams; K. Winward; K. Work; B. Young; P. E. Young; P. Zapata; R. E. Bahr; W. Seka; J. Fernandez; D. Montgomery; H. Rose

2004-01-01

288

Visual Scanning Hartmann Optical Tester (VSHOT) Uncertainty Analysis (Milestone Report)  

SciTech Connect

In 1997, an uncertainty analysis was conducted of the Video Scanning Hartmann Optical Tester (VSHOT). In 2010, we have completed a new analysis, based primarily on the geometric optics of the system, and it shows sensitivities to various design and operational parameters. We discuss sources of error with measuring devices, instrument calibrations, and operator measurements for a parabolic trough mirror panel test. These help to guide the operator in proper setup, and help end-users to understand the data they are provided. We include both the systematic (bias) and random (precision) errors for VSHOT testing and their contributions to the uncertainty. The contributing factors we considered in this study are: target tilt; target face to laser output distance; instrument vertical offset; laser output angle; distance between the tool and the test piece; camera calibration; and laser scanner. These contributing factors were applied to the calculated slope error, focal length, and test article tilt that are generated by the VSHOT data processing. Results show the estimated 2-sigma uncertainty in slope error for a parabolic trough line scan test to be +/-0.2 milliradians; uncertainty in the focal length is +/- 0.1 mm, and the uncertainty in test article tilt is +/- 0.04 milliradians.

Gray, A.; Lewandowski, A.; Wendelin, T.

2010-10-01

289

Application study of the optical biopsy system for small experimental animals  

NASA Astrophysics Data System (ADS)

An optical biopsy system for small experimental animals has been developed. The system includes endoscope probe, portable probe and two kinds of miniaturized Raman probes. The micro Raman probe (MRP) is made of optical fibers and the ball lens hollow optical fiber Raman probe (BHRP) is made of hollow fiber. The former has large focal depth and suitable to measure average spectra of subsurface tissue. The latter has rather small focal depth and it is possible to control focal length by selecting ball lens attached at the probe head. It is suitable to survey materials at the fixed depth in the tissue. The system is applied to study various small animal cancer models, such as esophagus and stomach rat models and subcutaneous mouse models of pancreatic cancers. In the studies of subcutaneous tumor model mouse, it is suggested that protein conformational changes occur in the tumor tissue within few minutes after euthanasia of the mouse. No more change is observed for the following ten minutes. Any alterations in the molecular level are not observed in normal skin, muscle tissues. Since the change completes in such a short time, it is suggested that this phenomenon caused by termination of blood circulation.

Sato, Hidetoshi; Suzuki, Toshiaki; Morita, Shin-ichi; Maruyama, Atsushi; Shimosegawa, Toru; Matsuura, Yuji; Kanai, Gen'ichi; Ura, Nobuo; Masutani, Koji; Ozaki, Yukihiro

2008-02-01

290

Optical tracking of a microscope for image-guided intranasal sinus surgery.  

PubMed

The objective of this study was to examine the effects of optical and tracking properties on the accuracy of an optically locatable operating microscope. The intraoperative arrangement was based on experimental results obtained from a skull model. Measurements were taken from 24 patients undergoing intranasal microscopic sinus surgery for various disorders. Two major groups of influencing factors were determined from measurements on the model: 1) optical properties of the microscope, such as the method of focal point adjustment, focal length, and magnification of the lens; and 2) tracking properties of the microscope, such as the distance of the digitizer to the tracked object, the number of reference infrared light-emitting diodes (IR-LEDs), and the area circumscribed by these IR-LEDs. Patient measurements showed an overall spatial error of 2.39+/-1.15 mm with a laser-supported adjustment of the focal point of the microscope. Although the associated 95th percentile was at 4.36 mm, such a value is encouraging for further development of microscopically navigable systems. It must be noted that the noninvasive patient-to-image registration was performed on the basis of a computed tomographic image with a slice distance of 2 mm. PMID:9930541

Hauser, R; Westermann, B

1999-01-01

291

Determining the focal mechanisms of earthquakes by full waveform modeling  

E-print Network

Determining the focal mechanism of an earthquake helps us to better characterize reservoirs, define faults, and understand the stress and strain regime. The objective of this thesis is to find the focal mechanism and depth ...

Busfar, Hussam A. (Hussam Abdullah)

2009-01-01

292

Extended depth of focus adaptive optics spectral domain optical coherence tomography  

PubMed Central

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

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

2012-01-01

293

Likelihood analysis of earthquake focal mechanism distributions  

E-print Network

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. In this work we apply a conventional likelihood method to measure a skill of forecast. The advantage of such an approach is that earthquake rate prediction can in principle be adequately combined with focal mechanism forecast, if both are based on the likelihood scores, resulting in a general forecast optimization. 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. For double-couple source orientation the random probability distribution function is not uniform, which complicates the calculation of the likelihood value. To better understand the resulting complexities we calculate the information (likelihood) score for two rota...

Kagan, Y Y

2014-01-01

294

Physical Activity Performance of Focal Middle School Students  

ERIC Educational Resources Information Center

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…

Erfle, Stephen E.; Gelbaugh, Corey M.

2013-01-01

295

Focal Dermal Hypoplasia Syndrome (Goltz Syndrome)  

Microsoft Academic Search

The focal dermal hypoplasia (FDH) syndrome is a rare congenital condition (OMIM # 305600) that, as often occurs with other\\u000a neurocutaneous disorders, can affect various ectodermal and mesodermal tissues besides the skin. The skin manifestations predominate\\u000a and are essential for the diagnosis: these include atrophy and linear pigmentation of the skin, herniation of the fat through\\u000a dermal defects and multiple

Ignacio Pascual-Castroviejo; Martino Ruggieri

296

MR imaging of benign focal liver lesions.  

PubMed

Focal liver lesions (FLLs) are commonly encountered on routine imaging studies. Most lesions detected are benign, but many are indeterminate at the time of initial imaging. This article reviews the important role of MR imaging for the detection and characterization of various benign FLLs while illustrating typical imaging appearances and potential pitfalls in interpretation. The utility of diffusion-weighted imaging and hepatocyte-specific contrast agents is also discussed. PMID:24889166

Cogley, Jonathan R; Miller, Frank H

2014-07-01

297

Focality and Topicality Marking in Biloxi  

E-print Network

discourse and that these are related in the GH shown below (ibid, 1993). Fig. 1 Six cognitive statuses of the GH IN FOCUS ACTIVATED FAMILIAR UNIQUELY REFERENTIAL TYPE...Focality and Topicality Marking in Biloxi1 David V. Kaufman University of Kansas 1. Introduction The purpose of this paper is to explore the use of two clitics that appear as discourse markers in Biloxi (ISO 639-3 bll) narratives...

Kaufman, David V.

2008-01-01

298

Minimal change nephropathy and focal segmental glomerulosclerosis  

Microsoft Academic Search

The terms minimal change nephropathy and focal segmental glomerulosclerosis describe histopathological entities diagnosed\\u000a by renal biopsy, typically in patients presenting with heavy proteinuria and its consequences including nephrotic syndrome.\\u000a Numerous alterations in the immune response have been reported, but there is uncertainty about whether these play a causal\\u000a role. In both conditions, there is evidence of injury to glomerular epithelial

Peter W. Mathieson

2007-01-01

299

Active MMW Focal Plane Imaging System  

Microsoft Academic Search

\\u000a Millimeter wave imaging technology has received a lot of attention in recent years. It has been widely applied in aircraft\\u000a landing guidance system, dangerous substance inspection, plasma tests and human carry on safety inspection. It can be applied\\u000a in many areas in the future. This paper studies an active millimeter wave focal plane imaging system. Among the theory and\\u000a key

Pingang Su; Zongxin Wang; Zhengyu Xu

2009-01-01

300

Upper Extremity Length Equalization  

PubMed Central

Significant upper extremity length inequality is uncommon but can cause major functional problems. The ability to position and use the hand may be impaired by shortness of any of the long bones of the upper extremity. In many respects upper and lower extremity length problems are similar. They most commonly occur after injury to a growing bone and the treatment modalities utilized in the lower extremity may be applied to the upper extremity. These treatment options include epiphysiodesis, shortening osteotomy, angulatory correction osteotomy and lengthening. This report reviews the literature relative to upper extremity length inequality and equalization and presents an algorithm for evaluation and planning appropriate treatment for patients with this condition. This algorithm is illustrated by two clinical cases of posttraumatic shortness of the radius which were effectively treated. ImagesFigure 1Figure 2Figure 3

DeCoster, Thomas A.; Ritterbusch, John; Crawford, Mark

1992-01-01

301

Coronagraphic phase diversity: a simple focal plane sensor for high-contrast imaging.  

PubMed

Exoplanet direct imaging is a challenging goal of today's astronomical instrumentation. Several high-contrast imaging instruments dedicated to this task are currently being integrated; they are ultimately limited by the presence of quasi-static speckles in the imaging focal plane. These speckles originate in residual quasi-static optical aberrations, which must be measured and compensated for, typically at a nanometric level. We present a novel focal plane wavefront sensor (WFS) designed for this particular application. It is an extension of the phase diversity technique to coronagraphic imaging. This sensor requires no dedicated hardware and uses only two scientific images differing from a known aberration, which can be conveniently introduced by the adaptive optics subsystem. The aberrations are therefore calibrated all the way down to the scientific camera, without any differential aberrations between the sensor and the scientific camera. We show the potential of this WFS by means of simulations, and we perform a preliminary experimental validation. PMID:23202053

Sauvage, J-F; Mugnier, L; Paul, B; Villecroze, R

2012-12-01

302

Gaze Movement & Focal Points Perceptual and Artistic Principles for  

E-print Network

during the ballistic movement ­ We "suppress" our vision while the gaze moves #12;Gaze Movement & Focal · Evolution of saliency #12;Gaze Movement & Focal Points Further reading Vision Science, from photonsGaze Movement & Focal Points Perceptual and Artistic Principles for Effective Computer Depiction

Durand, Frédo

303

Use of focal mechanisms to determine stress: A control study  

Microsoft Academic Search

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

Andrew Jay Michael

1987-01-01

304

DESIGNATION OF FOCAL VERTEBRATE SPECIES FOR THE LAKE TAHOE BASIN  

E-print Network

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 Candidates for Focal Species Status Only species presumed to have established populations in the basin

Standiford, Richard B.

305

STATISTICAL PROPERTIES OF FOCAL CONIC TEXTURES IN SMECTIC LIQUID CRYSTALS  

E-print Network

will usually break up into focal conics, as explained in section (2.3). Article published online by EDP661 STATISTICAL PROPERTIES OF FOCAL CONIC TEXTURES IN SMECTIC LIQUID CRYSTALS R. BIDAUX, N. BOCCARA layers, one obtains a focal conic texture. We consider here the most familiar case where each unit

Paris-Sud XI, Université de

306

Epileptic seizures triggered directly by focal transcranial magnetic stimulation  

Microsoft Academic Search

Focal, secondarily generalizing epileptic seizures were released by magnetic stimulation in a patient with focal epilepsy. The stimulation induced seizures had a similar clinical appearance to the patient's spontaneous seizures. They were released exclusively by an angulated “figure-of-8” coil which stimulates the brain more focally as compared to the commonly used flat round coil. The epileptic focus could be located

J. Classen; O. W. Witte; G. Schlaug; R. J. Seitz; H. Holthausen; R. Benecke

1995-01-01

307

Focus in Grade 1: Teaching with Curriculum Focal Points  

ERIC Educational Resources Information Center

"Focus in Grade 1: Teaching with Curriculum Focal Points" describes and illustrates learning paths for the mathematical concepts and skills of each grade 1 Focal Point as presented in Curriculum Focal Points for Prekindergarten through Grade 8 Mathematics. It includes representational supports for teaching and learning that can facilitate…

Fuson, Karen; Clements, Douglas; Beckmann, Sybilla

2010-01-01

308

A Computational Model of Acute Focal Cortical Lesions  

E-print Network

A Computational Model of Acute Focal Cortical Lesions Sharon Goodall, MS , James A. Reggia, MD Ph, and the anonymous reviewers, for helpful comments on this work. #12;A Computational Model of Acute Focal Cortical, was subjected to acute focal damage. The perilesion excitability and cortical map reorganization were measured

Ruppin, Eytan

309

Characterization of a CZT focal plane small prototype for hard X-ray telescope  

Microsoft Academic Search

The promise of good energy and spatial resolution coupled with high efficiency and room temperature operation has fuelled a large international effort to develop cadmium zinc telluride (CZT) for hard X-ray applications. We are involved on the development of a hard X-ray telescope based on multilayer optics and focal plane detector operative in the 10-80 keV energy range. This telescope

S. Del Sordo; L. Abbene; M. Zora; G. Agnetta; B. Biondo; A. Mangano; F. Russo; E. Caroli; N. Auricchio; A. Donati; F. Schiavone; J. B. Stephen; G. Ventura; G. Bertuccio; S. Caccia; M. Sampietro

2005-01-01

310

Focal plane wave-front sensing algorithm for high-contrast imaging  

Microsoft Academic Search

High-contrast imaging provided by a coronagraph is critical for the direction imaging of the Earth-like planet orbiting its\\u000a bright parent star. A major limitation for such direct imaging is the speckle noise that is induced from the wave-front error\\u000a of an optical system. We derive an algorithm for the wave-front measurement directly from 3 focal plane images. The 3 images

Jiangpei Dou; Deqing Ren; Yongtian Zhu; Xi Zhang

2009-01-01

311

Mappability and read length  

PubMed Central

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.

Li, Wentian; Freudenberg, Jan

2014-01-01

312

Laser optics protective device  

NASA Astrophysics Data System (ADS)

A broadband thermal optical limiter disposed between a laser oscillator and a laser amplifier system for protecting optical components in the laser oscillator from damage due to amplified optical feedback from the laser amplifier system at all near ultraviolet, visible, and near infrared wavelengths is disclosed. The thermal optical limiter comprises: a first lens for focusing the amplified optical feedback to a focal point on an optical axis; a flowing dye cell disposed near the focal point and being responsive to the focused amplified optical feedback for thermally defocusing and aberrating the focused amplified optical feedback into a plurality of rings about the optical axis; a second lens for passing only a small portion of the defocused amplified optical feedback; and a blocking aperture disposed around the second lens for blocking substantially all of the thermally defocused amplified optical feedback from the flowing dye cell and passing therethrough into the second lens only a small portion of the thermally defocused amplified optical feedback from the flowing dye cell.

Huston, Alan L.; Justus, Brian L.; Merrit, Charles D.; Campillo, Anthony J.

1994-11-01

313

Focal plane actuation to achieve ultra-high resolution on suborbital balloon payloads  

NASA Astrophysics Data System (ADS)

Over the past few years there has been remarkable success flying imaging telescope systems suspended from suborbital balloon payload systems. These imaging systems have covered optical, ultraviolet, sub-­-millimeter and infrared passbands (i.e. BLAST, STO, SBI, Fireball and others). In recognition of these advances NASA is now considering ambitious programs to promote planetary imaging from high altitude at a fraction of the cost of similar fully orbital systems. The challenge with imaging from a balloon payload is delivering the full diffraction-­-limited resolution of the system from a moving payload. Good progress has been made with damping mechanisms and oscillation control to remove most macroscopic movement in the departures of the imaging focal plane from a static configuration, however a jitter component remains that is difficult to remove using external corrections. This paper reports on work to demonstrate in the laboratory the utility and performance of actuating a detector focal plane (of whatever type) to remove the final jitter terms using an agile hexapod design. The input to this demonstration is the jitter signal generated by the pointing system of a previously flown balloon mission (the Stratospheric Terahertz Observatory, STO). Our group has a mature jitter compensation system that thermally isolates the control head from the focal plane itself. This allows the hexapod to remain at ambient temperature in a vacuum environment with the focal plane cooled to cryogenic temperatures. Our lab design mounts the focal plane on the hexapod in a custom cryostat and delivers an active optical stimulus together with the corresponding jitter signal, using the actuation of the hexapod to correct for the departures from a static, stable configuration. We believe this demonstration will make the case for inclusion of this technological solution in future balloon-­-borne imaging systems requiring ultra-­-high resolution.

Scowen, Paul A.; Miller, Alex; Challa, Priya; Veach, Todd; Groppi, Chris; Mauskopf, Phil

2014-07-01

314

Imaging Polarimetry With Polarization-Sensitive Focal Planes  

NASA Astrophysics Data System (ADS)

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.

Vorobiev, Dmitry; Ninkov, Z.

2014-01-01

315

Corrugated Quantum Well Infrared Photodetector Focal Plane Array Test Results  

NASA Technical Reports Server (NTRS)

The corrugated quantum-well infrared photodetector (C-QWIP) uses total internal reflection to couple normal incident light into the optically active quantum wells. The coupling efficiency has been shown to be relatively independent of the pixel size and wavelength thus making the C-QWIP a candidate for detectors over the entire infrared spectrum. The broadband coupling efficiency of the C-QWIP makes it an ideal candidate for multiwavelength detectors. We fabricated and tested C-QWIP focal plane arrays (FPAs) with cutoff wavelengths of 11.2 and 16.2 micrometers. Each FPA has 256 x 256 pixels that are bump-bonded to a direct injection readout circuit. Both FPAs provided infrared imagery with good aesthetic attributes. For the 11.2-micrometers FPA, background-limited performance (BLIP) was observed at 60 K with f/3 optics. For the 16.2-micrometers FPA, BLIP was observed at 38 K. Besides the reduction of dark current in C-QWIP structures, the measured internal quantum efficiency (eta) remains to be high. The values for responsivity and quantum efficiency obtained from the FPA results agree well with those measured for single devices.

Goldberg, A.; Choi, K. K.; Das, N. C.; La, A.; Jhabvala, M.

1999-01-01

316

Reflection aspherical microlenses for planar optics fabricated by electron-beam lithography.  

PubMed

Reflection aspherical microlenses are proposed for planar optics. These microlenses have the structure of a nonconcentric elliptical concave mirror. Broadband light can be used for these microlenses because these microlenses have no chromatic aberration. The microlens fabricated by electron-beam lithography and Ag deposition was found to have a smooth surface as designed. The focal length of the microlens was constant independent of the wavelength. The measured spot sizes agreed with diffraction-limited values at two different wavelengths. By using the array of this microlens, multiple images with excellent contrast were obtained under incoherent white-light illumination. PMID:19794559

Shiono, T; Ogawa, H

1992-04-15

317

Focal adhesions as mechanosensors: the two-spring model  

E-print Network

Adhesion-dependent cells actively sense the mechanical properties of their environment through mechanotransductory processes at focal adhesions, which are integrin-based contacts connecting the extracellular matrix to the cytoskeleton. Here we present first steps towards a quantitative understanding of focal adhesions as mechanosensors. It has been shown experimentally that high levels of force are related to growth of and signaling at focal adhesions. In particular, activation of the small GTPase Rho through focal adhesions leads to the formation of stress fibers. Here we discuss one way in which force might regulate the internal state of focal adhesions, namely by modulating the internal rupture dynamics of focal adhesions. A simple two-spring model shows that the stiffer the environment, the more efficient cellular force is built up at focal adhesions by molecular motors interacting with the actin filaments.

Ulrich S. Schwarz; Thorsten Erdmann; Ilka B. Bischofs

2006-08-03

318

Limits of spectral resolution in optical measurements  

NASA Astrophysics Data System (ADS)

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.

Marques, Manuel B.

2014-08-01

319

Adaptation in the optical properties of the crystalline lens in the eyes of the Lessepsian migrant Siganus rivulatus.  

PubMed

Vision is an important source of information for many animals. The crystalline lens plays a central role in the visual pathway and hence the ecology of fishes. In this study, we tested whether the different light regimes in the Mediterranean and Red Seas have an effect on the optical properties of the lenses in the rivulated rabbitfish, Siganus rivulatus. This species has migrated through the Suez Canal from the Red Sea and established a vital population in the Mediterranean Sea. Longitudinal spherical aberration curves and focal lengths of the fish lenses were measured by laser scans and compared between the two populations. In addition, rivulated rabbitfish from the Mediterranean Sea were exposed to colored light (yellow, green and blue) and unfiltered light for periods of 1 or 13 days to test for short-term adjustments. Lens focal length was significantly longer (3%) in the Rea Sea population. The shorter focal length of the Mediterranean population can be explained as an adaptation to the dimmer light environment, as this difference makes the Mediterranean eyes 5% more sensitive than the eyes of the Red Sea population. The difference may be due to genetic differences or, more likely, adaptive developmental plasticity. Short-term regulatory mechanisms do not seem to be involved. PMID:21795569

Gagnon, Yakir L; Shashar, Nadav; Kröger, Ronald H H

2011-08-15

320

Planck-Length Phenomenology  

E-print Network

This author's recent proposal of interferometric tests of Planck-scale-related properties of space-time is here revisited from a strictly phenomenological viewpoint. The results announced previously are rederived using elementary dimensional considerations. The dimensional analysis is then extended to the other two classes of experiments (observations of neutral kaons at particle accelerators and observations of the gamma rays we detect from distant astrophysical sources) which have been recently considered as opportunities to explore "foamy" properties of space-time. The emerging picture suggests that there is an objective and intuitive way to connect the sensitivities of these three experiments with the Planck length. While in previous studies the emphasis was always on some quantum-gravity scenario and the analysis was always primarily aimed at showing that the chosen scenario would leave a trace in a certain class of doable experiments, the analysis here reported takes as starting point the experiments and, by relating in a direct quantitative way the sensitivities to the Planck length, provides a model-independent description of the status of Planck-length phenomenology.

Giovanni Amelino-Camelia

2000-08-04

321

Focal hepatic infarction with bile lake formation  

SciTech Connect

Venous thrombosis associated with oral contraceptives is a well recognized phenomenon. Arterial thrombosis, while less common, is also a known risk, as evidenced by the increased incidence of cerebral vascular accidents and myocardial ischemia or infarction. The liver is relatively protected from the usual consequences of arterial thrombosis because of its dual blood supply. The authors present an unusual case of a young woman with a history of oral contraceptive and cigarette use who developed hepatic artery thrombosis and had focal liver lesions on computed tomography (CT) due to hepatic infarction and bile lake formation despite an intact portal venous system.

Peterson, I.M.; Neumann, C.H.

1984-06-01

322

Lateral Shear Forces Applied to Cells with Single Elastic Micropillars to Influence Focal Adhesion Dynamics  

PubMed Central

Focal adhesions (FAs) are important adhesion sites between eukaryotic cells and the extracellular matrix, their size depending on the locally applied force. To quantitatively study the mechanosensitivity of FAs, we induce their growth and disassembly by varying the distribution of intracellular stress. We present a novel method for micromanipulation of living cells to explore the dynamics of focal adhesion (FA) assembly under force. Fibroblasts are sheared laterally to their adhesion surface with single PDMS micropillars in order to apply laterally stretch or compression to focal adhesions. This allows for measuring the shear force exerted by the micropillar and correlates it with FA length and growth velocity. Furthermore, we analyze the resulting dynamics of FA molecules (paxillin) and compare intensity profiles along FAs before and after the application of external force. The responses of stretched and relaxed FAs differ fundamentally: Relaxed and compressed FAs disassemble isotropically and show no length variation while stretched FAs grow unisotropically in the direction of the applied force and show protein influx only at their front. PMID:21386435

Heil, Patrick; Spatz, Joachim P

2013-01-01

323

Optical design of solar blind ultraviolet warning system  

NASA Astrophysics Data System (ADS)

Ultraviolet warning technology is one of the important methods for missile warning. "Solar blind region" provides a very effective way to detect the target for missile approaching alarm. In order to find the target by detecting the ultraviolet radiation of missile efflux plasma, ultraviolet optical system design of large field of view and large relative aperture is the key for the technology of ultraviolet detection. From the academic point of view, the structure parameters are determined for 2048×2048 ultraviolet CCD detector according to the requirements of ultraviolet warning system. The refractive ultraviolet warning optical system is designed for 0.24?m ~0.28?m wave band with ZEMAX optical design software. The focal length is 41mm, the field of view is 46°and the relative aperture is 1:3.5. In order to ensure the detected energy, aspherical and binary surface are adopted to reduce the aberration and spot size of the system. Within the 0.8 field of view RMS of spot diagram is less than 13?m. It is smaller than the pixel size 13.5?m of ultraviolet CCD. The energy concentration is more than 80%. This optical system has long focal length and large relative aperture that meet the energy requirements of warning system. Large field of view can satisfy the range of searching targets. The spot diagram RMS of each field of view is so small that can meet the requirement of image quality. In addition, the system is composed of six lenses. The structure of it is simple, the volume is small and the application is very convenient.

Li, Quanyong; Xu, Chunyun; Dong, Jianing

2012-11-01

324

The impact of domestication on the chicken optical apparatus.  

PubMed

Domestication processes tend to release animals from natural selection and favour traits desired by humans, such as food-production and co-operative behaviour. A side effect of such selective breeding is the alteration of unintended traits. In this paper, we investigate how active selection for egg production in chickens has affected the visual system, in particular the optical sensitivity that relates to the ability of chickens to see in dim light. We measured eye dimensions as well as the pupil diameter at different light intensities (the steady state pupil dynamics), in adult male and female White Leghorns and the closest relatives to their ancestor, the Red Junglefowls. With this information, we calculated the focal length and optical sensitivity (f-number) of the eyes. Males have larger eyes than females in both breeds and White Leghorn eyes are larger than those of Red Junglefowls in both sexes. The steady state pupil dynamics is less variable, however, the combination of pupil dynamics and eye size gives a higher optical sensitivity in Red Junglefowl eyes than in White Leghorns at light intensities below approximately 10 cd/m(2). While eye size and focal length match the larger body size in White Leghorns compared to Red Junglefowls, the steady state pupil dynamics do not. The reason for this is likely to be that eye morphology and the neuro-muscular control of the pupil have been affected differently by the strong selection for egg production and the simultaneous release of the selection pressure for high performing vision. This study is the first description of how optical sensitivity has changed in a domesticated species and our results demonstrate important considerations regarding domestication processes and sensory ability. PMID:23776492

Roth, Lina S V; Lind, Olle

2013-01-01

325

The Impact of Domestication on the Chicken Optical Apparatus  

PubMed Central

Domestication processes tend to release animals from natural selection and favour traits desired by humans, such as food-production and co-operative behaviour. A side effect of such selective breeding is the alteration of unintended traits. In this paper, we investigate how active selection for egg production in chickens has affected the visual system, in particular the optical sensitivity that relates to the ability of chickens to see in dim light. We measured eye dimensions as well as the pupil diameter at different light intensities (the steady state pupil dynamics), in adult male and female White Leghorns and the closest relatives to their ancestor, the Red Junglefowls. With this information, we calculated the focal length and optical sensitivity (f-number) of the eyes. Males have larger eyes than females in both breeds and White Leghorn eyes are larger than those of Red Junglefowls in both sexes. The steady state pupil dynamics is less variable, however, the combination of pupil dynamics and eye size gives a higher optical sensitivity in Red Junglefowl eyes than in White Leghorns at light intensities below approximately 10 cd/m2. While eye size and focal length match the larger body size in White Leghorns compared to Red Junglefowls, the steady state pupil dynamics do not. The reason for this is likely to be that eye morphology and the neuro-muscular control of the pupil have been affected differently by the strong selection for egg production and the simultaneous release of the selection pressure for high performing vision. This study is the first description of how optical sensitivity has changed in a domesticated species and our results demonstrate important considerations regarding domestication processes and sensory ability. PMID:23776492

2013-01-01

326

Optical instruments  

NASA Technical Reports Server (NTRS)

A wide angle, low focal ratio, high resolution, catoptric, image plane scanner is described. The scanner includes the following features: (1) a reflective improvement on the Schmidt principle, (2) a polar line scanner in which all field elements are brought to and corrected on axis, and (3) a scanner arrangement in which the aperture stop of the system is imaged at the center of curvature of a spherical primary mirror. The system scans are a large radial angle and an extremely high rate of speed with relatively small scanning mirrors. Because the system is symmetrical about the optical axis, the obscuration is independent of the scan angle.

Abel, I. R. (inventor)

1974-01-01

327

Adaptive optical probe design for optical coherence tomography and microscopy using tunable optics.  

PubMed

We present a tunable, adaptive optical imaging probe for multimodal imaging such as optical coherence tomography and microscopy. The probe is compatible with forward-looking scanning laser imaging devices such as an endoscope. The lens configuration includes a tunable iris and two varifocal lenses, both driven by microelectrofluidics, as well as several conventional fixed focus lenses. The modulation transfer function and spot size in the focal plane is evaluated, and we show using optical simulations that there are three possible imaging modes with different transverse resolutions and focal depths. PMID:23389140

Choi, Minseog; Lee, Seungwan; Chang, Jong-Hyeon; Lee, Eunsung; Jung, Kyu-Dong; Kim, Woonbae

2013-01-28

328

Fast nonparaxial scalar focal field calculations.  

PubMed

An efficient algorithm for calculating nonparaxial scalar field distributions in the focal region of a lens is discussed. The algorithm is based on fast Fourier transform implementations of the first Rayleigh-Sommerfeld diffraction integral and assumes that the input field at the pupil plane has a larger extent than the field in the focal region. A sampling grid is defined over a finite region in the output plane and referred to as a tile. The input field is divided into multiple separate spatial regions of the size of the output tile. Finally, the input tiles are added coherently to form a summed tile, which is propagated to the output plane. Since only a single tile is propagated, there are significant reductions of computational load and memory requirements. This method is combined either with a subpixel sampling technique or with a chirp z-transform to realize smaller sampling intervals in the output plane than in the input plane. For a given example the resulting methods enable a speedup of approximately 800× in comparison to the normal angular spectrum method, while the memory requirements are reduced by more than 99%. PMID:24977358

Hillenbrand, Matthias; Hoffmann, Armin; Kelly, Damien P; Sinzinger, Stefan

2014-06-01

329

Posttraumatic focal dystonia of the shoulder.  

PubMed

Focal posttraumatic shoulder dystonia is a rare and not easily identifiable entity. Its true pathophysiologic nature, predisposing factors, and disease course remain debatable.This article describes a rare case of a 40-year-old man with late symptoms of focal shoulder dystonia after peripheral trauma of his left shoulder girdle. The shoulder was indirectly injured from the impact of a fall off his motorbike 3 years earlier. He was referred to the authors' institution because remarkable reduction of arm abduction, muscle spasms, and circumscribed hypertrophy of the trapezius muscle were noted while his head and neck were in neutral position and had a full range of motion. The left shoulder had a fixed elevated posture compared with the contralateral shoulder. A continuous burning pain was localized over the area of the hypertrophied trapezius muscle, radiating to the ipsilateral side of the head and neck. Dystonic movements of the trapezius, rhomboid, and supraspinatus muscles were observed. The abduction of the shoulder was significantly decreased, and any repetitive effort for arm abduction induced an exaggeration of his movement disorder, leading to a more pronounced shoulder elevation.Plain radiographs and magnetic resonance imaging of the left shoulder revealed a suprascapular tendinitis with no other abnormalities. Repeated needle electromyography of the left trapezius muscle and neurography of the accessory nerve on both sides were normal. Injections of botulinum toxin A were effective in the resolution of muscle hypertrophy and abnormal posture. PMID:22691679

Vasileiadis, Georgios I; Sakellariou, Vasileios I; Papagelopoulos, Panayiotis J; Zoubos, Aristeides B

2012-06-01

330

Fast & Furious focal-plane wavefront sensing  

E-print Network

We present two complementary algorithms suitable for using focal-plane measurements to control a wavefront corrector with an extremely high spatial resolution. The algorithms use linear approximations to iteratively minimize the aberrations seen by the focal-plane camera. The first algorithm, Fast & Furious (FF), uses a weak-aberration assumption and pupil symmetries to achieve fast wavefront reconstruction. The second algorithm, an extension to FF, can deal with an arbitrary pupil shape; it uses a Gerchberg-Saxton style error reduction to determine the pupil amplitudes. Simulations and experimental results are shown for a spatial light modulator controlling the wavefront with a resolution of 170 x 170 pixels. The algorithms increase the Strehl ratio from ~0.75 to 0.98-0.99, and the intensity of the scattered light is reduced throughout the whole recorded image of 320 x 320 pixels. The remaining wavefront rms error is estimated to be ~0.15 rad with FF and ~0.10 rad with FF-GS.

Korkiakoski, Visa; Doelman, Niek; Kenworthy, Matthew; Otten, Gilles; Verhaegen, Michel

2014-01-01

331

Fast & Furious focal-plane wavefront sensing.  

PubMed

We present two complementary algorithms suitable for using focal-plane measurements to control a wavefront corrector with an extremely high-spatial resolution. The algorithms use linear approximations to iteratively minimize the aberrations seen by the focal-plane camera. The first algorithm, Fast & Furious (FF), uses a weak-aberration assumption and pupil symmetries to achieve fast wavefront reconstruction. The second algorithm, an extension to FF, can deal with an arbitrary pupil shape; it uses a Gerchberg-Saxton (GS)-style error reduction to determine the pupil amplitudes. Simulations and experimental results are shown for a spatial-light modulator controlling the wavefront with a resolution of 170×170??pixels. The algorithms increase the Strehl ratio from ?0.75 to 0.98-0.99, and the intensity of the scattered light is reduced throughout the whole recorded image of 320×320??pixels. The remaining wavefront rms error is estimated to be ?0.15??rad with FF and ?0.10??rad with FF-GS. PMID:25090079

Korkiakoski, Visa; Keller, Christoph U; Doelman, Niek; Kenworthy, Matthew; Otten, Gilles; Verhaegen, Michel

2014-07-10

332

Three-course graduate electro-optics laboratory sequence at the University of Dayton  

NASA Astrophysics Data System (ADS)

The UD Electro-Optics Graduate Program offers the M.S. and Ph.D. degrees. It is an interdisciplinary program between the Electrical and Computer Engineering Department and the Physics Department and is designed for students with a B.S. in either of these fields. In order to strengthen skills in applied optics, optical measurement techniques, photonics and data acquisition and analysis methods, a required three- course laboratory sequence was designed. The first course in the fall term has seven basic optics projects that include focal length measurements, lens systems, radiation detection, polarization, interference, near and far field diffraction, interferometry and coherence. The first half of the second course, given in the summer term, covers fiber optics and fiber optical systems. In the second half, the students propose, design, construct, test and report on an electro-optical/photonics system. The third course in the fall term has five advanced projects on the topics of optical spectroscopy, holography, characterization of lasers, laser Doppler velocimetry and optical pattern recognition. Details on the design of these courses are presented along with examples of student work and the results of student evaluations and responses to the lab program.

Yaney, Perry P.; Duncan, Bradley D.; Little, Gordon R.

2002-05-01

333

LSST Camera Optics Design  

SciTech Connect

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.

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

334

Studying ATHENA optics with divergent and collimated x-ray beams  

NASA Astrophysics Data System (ADS)

An open question in the measurement of X-ray optics for satellite experiments is what the PSF (point spread function) looks like in orbit and what the focal length for a source at infinite distance is. In order to measure segmented optics as proposed for ATHENA a collimated X-ray beam with a size of several square centimeters is necessary. We showed that by using a zone plate such a collimated beam can be achieved. We discuss here the requirements such a zone plate collimator has to comply in order to characterize with this collimator an ATHENA type optic. Additional we can present results obtained with a first version of such a collimator and can show so the proof of principle.

Menz, Benedikt; Bräuninger, Heinrich; Burwitz, Vadim; Hartner, Gisela; Predehl, Peter

2014-07-01

335

Demonstration of an optimised focal field with long focal depth and high transmission obtained with the Extended Nijboer-Zernike theory.  

PubMed

In several optical systems, a specific Point Spread Function (PSF) needs to be generated. This can be achieved by shaping the complex field at the pupil. The Extended Nijboer-Zernike (ENZ) theory relates complex Zernike modes on the pupil directly to functions in the focal region. In this paper, we introduce a method to engineer a PSF using the ENZ theory. In particular, we present an optimization algorithm to design an extended depth of focus with high lateral resolution, while keeping the transmission of light high (over 60%). We also have demonstrated three outcomes of the algorithm using a Spatial Light Modulator (SLM). PMID:24514993

Konijnenberg, A P; Wei, L; Kumar, N; Filho, L Couto Correa Pinto; Cisotto, L; Pereira, S F; Urbach, H P

2014-01-13

336

Length of stain dosimeter  

NASA Technical Reports Server (NTRS)

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.

Lueck, Dale E. (inventor)

1994-01-01

337

Path length errors of VLBI antennas  

NASA Astrophysics Data System (ADS)

The performance of single dish radio antennas or telescopes is depending on the surface accuracy of the reflectors in the beam path and the focus/pointing errors induced by deviations/misalignment of the reflectors from a desired direction. For multiple dish VLBI arrays an additional mechanical effect, the path length stability, is a further source of performance degradation. For application at higher frequencies environmental influences as wind and temperature have to be considered additionally to the usually required manufacturing and alignment accuracies. Active measurement ("metrology") of the antenna deformations and their compensation by "active optics" (AO) respectively "flexible body compensation" (FBC) are established methods. For the path length errors AO or FBC are up to now not established methods. The paper describes how to handle the path length errors and the related metrology analogues to the established methods used for surface and focus/pointing error corrections.

Kaercher, Hans J.; Sust, Eberhard; Emde, Peter; Kühn, Jürgen

2010-07-01

338

CT appearance of focal fatty infiltration of the liver  

SciTech Connect

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.

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

1982-08-01

339

Deep Moonquake Focal Mechanisms: Recovery and Implications  

NASA Technical Reports Server (NTRS)

A defining characteristic of deep moonquakes is their tendency to occur with tidal periodicity, prompting previous studies to infer that they are related to the buildup and release of tidal stress within the Moon. In studies of tidal forcing, a key constraint is the focal mechanism: the fault parameters describing the type of failure moonquakes represent. The quality of the lunar seismic data and the limited source/receiver geometries of the Apollo seismic network prohibit the determination of deep moonquake fault parameters using first-motion polarities, as is typically done in terrestrial seismology. Without being able to resolve tidal stress onto a known failure plane, we can examine only gross qualities of the tidal stress tensor with respect to moonquake occurrence, so we cannot fully address the role of tidal stress in moonquake generation. We will examine the extent to which shear (S) and compression (P) wave amplitude ratios can constrain moonquake fault geometry by determining whether, for a given cluster, there exists a focal mechanism that can produce a radiation pattern consistent with the amplitudes measured by the Apollo instruments. Amplitudes are read in the ray coordinate frame, directly from seismograms for which the P and S arrivals are clearly identifiable on all long-period channels of the four Apollo stations. We apply an empirical station correction to account for site effects and the differences between P- and S-wave attenuation. Instead of focusing on the best fitting solution only, we formulate the inverse problem using a falsification criterion: all source orientations that do not reproduce the observed SV/P ratios within an error margin derived from the uncertainty of amplitude readings are rejected. All others are accepted as possible solutions. The inversion is carried out using an exhaustive grid search on a regular grid with predefined step size, encompassing all possible combinations of strike, dip and slip. To assess the sensitivity of the inversion for the uncertainty of the lunar interior structure, we carry out repeated inversions with different velocity structures. Our data set consist of a total of 106 events from 25 deep moonquake clusters. The largest contribution of 37 events originates from the most active cluster, A001, while other clusters are represented by 1 to 9 events. Since the definition of a cluster implies that all events share the same source orientation, a comparison of the inversion results of all events from one cluster will reduce ambiguities of the inversion. Once we obtain a suite of fault parameters for a given source, we can attempt to further constrain the focal mechanism with refined analyses of tidal stresses and predictions based on synthetic seismograms.

Knapmeyer, Martin; Weber, Renee C.

2011-01-01

340

Deep moonquake focal mechanisms: recovery and implications  

NASA Astrophysics Data System (ADS)

A defining characteristic of deep moonquakes is their tendency to occur with tidal periodicity, prompting previous studies to infer that they are related to the buildup and release of tidal stress within the Moon. In studies of tidal forcing, a key constraint is the focal mechanism: the fault parameters describing the type of failure moonquakes represent. The quality of the lunar seismic data and the limited source/receiver geometries of the Apollo seismic network prohibit the determination of deep moonquake fault parameters using first-motion polarities, as is typically done in terrestrial seismology. Without being able to resolve tidal stress onto a known failure plane, we can examine only gross qualities of the tidal stress tensor with respect to moonquake occurrence, so we cannot fully address the role of tidal stress in moonquake generation. We will examine the extent to which shear (S) and compression (P) wave amplitude ratios can constrain moonquake fault geometry by determining whether, for a given cluster, there exists a focal mechanism that can produce a radiation pattern consistent with the amplitudes measured by the Apollo instruments. Amplitudes are read in the ray coordinate frame, directly from seismograms for which the P and S arrivals are clearly identifiable on all long-period channels of the four Apollo stations. We apply an empirical station correction to account for site effects and the differences between P- and S-wave attenuation. Instead of focusing on the best fitting solution only, we formulate the inverse problem using a falsification criterion: all source orientations that do not reproduce the observed SV/P ratios within an error margin derived from the uncertainty of amplitude readings are rejected. All others are accepted as possible solutions. The inversion is carried out using an exhaustive grid search on a regular grid with predefined step size, encompassing all possible combinations of strike, dip and slip. To assess the sensitivity of the inversion for the uncertainty of the lunar interior structure, we carry out repeated inversions with different velocity structures. Our data set consist of a total of 106 events from 25 deep moonquake clusters. The largest contribution of 37 events originates from the most active cluster, A001, while other clusters are represented by 1 to 9 events. Since the definition of a cluster implies that all events share the same source orientation, a comparison of the inversion results of all events from one cluster will reduce ambiguities of the inversion. Once we obtain a suite of fault parameters for a given source, we can attempt to further constrain the focal mechanism with refined analyses of tidal stresses and predictions based on synthetic seismograms.

Knapmeyer, M.; Weber, R. C.

2011-12-01

341

Indeterminate-length quantum coding  

E-print Network

The quantum analogues of classical variable-length codes are indeterminate-length quantum codes, in which codewords may exist in superpositions of different lengths. This paper explores some of their properties. The length observable for such codes is governed by a quantum version of the Kraft-McMillan inequality. Indeterminate-length quantum codes also provide an alternate approach to quantum data compression.

Benjamin Schumacher; Michael D. Westmoreland

2000-11-02

342

Oral focal mucinosis of palatal mucosa: A rare case report  

PubMed Central

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

Bharti, Vipin; Singh, Jagmohan

2012-01-01

343

Deep Moonquake Focal Mechanisms: Recovery and Implications  

NASA Technical Reports Server (NTRS)

A defining characteristic of deep moonquakes is their tendency to occur with tidal periodicity, prompting previous studies to infer that they are related to the buildup and release of tidal stress within the Moon [refs]. In studies of tidal forcing, a key constraint is the focal mechanism: the fault parameters describing the type of failure moonquakes represent. The quality of the lunar seismic data and the limited source/receiver geometries of the Apollo seismic network prohibit the determination of deep moonquake fault parameters using first-motion polarities, as is typically done in terrestrial seismology [ref]. Without being able to resolve tidal stress onto a known failure plane, we can examine only gross qualities of the tidal stress tensor with respect to moonquake occurrence, so we cannot fully address the role of tidal stress in moonquake generation.

Weber, Renee C.; Knapmeyer, Martin

2012-01-01

344

Focal cerebral lesions and painting abilities.  

PubMed

Focal lesions such as strokes significantly affect painting production in the vast majority of artists. In particular, painters, when they resume painting, show changes in their painting style. In exceptional cases, there may be an apparent improvement in style, but in most cases, the changes represent nothing short of deterioration. This, however, varies according to the hemisphere affected. Painters with left-hemisphere lesions tend to show an inability to deal adequately with perspective and also tend to use simplified colors with fewer nuances. One often witnesses an evolution toward simpler, often "naïve" techniques, and at times rigid geometric repetitive features. Painters with right-hemisphere lesions also become unable to represent tridimensionality. In addition, their figures are often drawn in very summary fashion, with lack of coordination between volumes and space and a chromatic impoverishment; their main problem, however, is visuospatial, leading to neglect of the left side of the canvas. PMID:24041319

Mazzucchi, Anna; Sinforiani, Elena; Boller, François

2013-01-01

345

Short wavelength infrared hybrid focal plane arrays  

NASA Technical Reports Server (NTRS)

The employment of area focal plane arrays (FPA) has made it possible to obtain second generation infrared imaging systems with high resolution and sensitivity. The Short Wavelength Infrared (SWIR) region (1-2.5 microns) is of importance for imaging objects at high temperature and under conditions of reflected sunlight. The present investigation is concerned with electrooptical characterization results for 32 x 32 SWIR detector arrays and FPAs which are suitable for use in a prototype imaging spectrometer. The employed detector material is Hg(1-x)Cd(x)Te grown by liquid phase epitaxy on a CdTe transparent substrate. Attention is given to details of processing, the design of the detector array, the multiplexer, the fabrication of the hybrid FPA, and aspects of performance.

Vural, K.; Blackwell, J. D.; Marin, E. C.; Edwall, D. D.; Rode, J. P.

1983-01-01

346

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

NASA Astrophysics Data System (ADS)

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.

Wang, X.; Yuan, Y.; Zhang, J.; Chen, Y.; Cheng, Y.

2014-10-01

347

1024 x 1024 pixel mid-wavelength and long-wavelength infrared QWIP focal plane arrays for imaging applications  

NASA Technical Reports Server (NTRS)

Mid-wavelength infrared (MWIR) and long-wavelength infrared (LWIR) 10(24) x 10(24) 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 (NEAT) of 17 mK at a 95 K operating temperature with f/2.5 optics at 300 K background and the LWIR detector array has demonstrated a NEAT of 13 mK at a 70 K operating temperature with the same optical and background conditions as the MWIR detector array after the subtraction of system noise. Both MWIR and LWIR focal planes have shown background limited performance (BLIP) at 90 K and 70 K operating temperatures respectively, with similar optical and background conditions. In this paper, we will discuss the performance in terms of quantum efficiency, NE(delta)T, uniformity, operability and modulation transfer functions.

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

2005-01-01

348

Observation of a Solar Flare at 4.3-mm. Wave-length  

Microsoft Academic Search

DURING a programme of solar observations at a wave-length of 4.3 mm., scans were made across the Sun on September 25, 26 and 27, 1957. The radio telescope used for these observations has a half-power beam-width of 6.7 minutes of arc. The antenna reflector is an aluminium paraboloid, 10 feet in diameter with a focal length of 35.8 inches. The

R. J. Coates

1958-01-01

349

Advancement in 17-micron pixel pitch uncooled focal plane arrays  

NASA Astrophysics Data System (ADS)

This paper provides an update of 17 micron pixel pitch uncooled microbolometer development at DRS. Since the introduction of 17 micron pitch 640x480 focal plane arrays (FPAs) in 2006, significant progress has been made in sensor performance and manufacturing processes. The FPAs are now in initial production with an FPA noise equivalent temperature difference (NETD), detector thermal time constant, and pixel operability equivalent or better than that of the current 25 micron pixel pitch production FPAs. NETD improvement was achieved without compromising detector thermal response or thermal time constant by simultaneous reduction in bolometer heat capacity and thermal conductance. In addition, the DRS unique "umbrella" microbolometer cavities were optically tuned to optimize detector radiation absorption for specific spectral band applications. The 17 micron pixel pitch FPAs are currently being considered for the next generation soldier systems such as thermal weapon sights (TWS), vehicle driver vision enhancers (DVE), digitally fused enhanced night vision goggles (DENVG) and unmanned air vehicle (UAV) surveillance sensors, because of overall thermal imaging system size, weight and power advantages.

Li, Chuan; Skidmore, George; Howard, Christopher; Clarke, Elwood; Han, C. J.

2009-05-01

350

Kalman filtering techniques for focal plane electric field estimation.  

PubMed

For a coronagraph to detect faint exoplanets, it will require focal plane wavefront control techniques to continue reaching smaller angular separations and higher contrast levels. These correction algorithms are iterative and the control methods need an estimate of the electric field at the science camera, which requires nearly all of the images taken for the correction. The best way to make such algorithms the least disruptive to science exposures is to reduce the number required to estimate the field. We demonstrate a Kalman filter estimator that uses prior knowledge to create the estimate of the electric field, dramatically reducing the number of exposures required to estimate the image plane electric field while stabilizing the suppression against poor signal-to-noise. In addition to a significant reduction in exposures, we discuss the relative merit of this algorithm to estimation schemes that do not incorporate prior state estimate history, particularly in regard to estimate error and covariance. Ultimately the filter will lead to an adaptive algorithm which can estimate physical parameters in the laboratory for robustness to variance in the optical train. PMID:23456009

Groff, Tyler D; Jeremy Kasdin, N

2013-01-01

351

Regional septal dysfunction in a three-dimensional computational model of focal myofiber disarray.  

PubMed

MLC2v/ras transgenic mice display a phenotype characteristic of hypertrophic cardiomyopathy, with septal hypertrophy and focal myocyte disarray. Experimental measurements of septal wall mechanics in ras transgenic mice have previously shown that regions of myocyte disarray have reduced principal systolic shortening, torsional systolic shear, and sarcomere length. To investigate the mechanisms of this regional dysfunction, a three-dimensional prolate spheroidal finite-element model was used to simulate filling and ejection in the hypertrophied mouse left ventricle with septal disarray. Focally disarrayed septal myocardium was modeled by randomly distributed three-dimensional regions of altered material properties based on measured statistical distributions of muscle fiber angular dispersion. Material properties in disarrayed regions were modeled by decreased systolic anisotropy derived from increased fiber angle dispersion and decreased systolic tension development associated with reduced sarcomere lengths. Compared with measurements in ras transgenic mice, the model showed similar heterogeneity of septal systolic strain with the largest reductions in principal shortening and torsional shear in regions of greatest disarray. Average systolic principal shortening on the right ventricular septal surface of the model was -0.114 for normal regions and -0.065 for disarrayed regions; for torsional shear, these values were 0.047 and 0.019, respectively. These model results suggest that regional dysfunction in ras transgenic mice may be explained in part by the observed structural defects, including myofiber dispersion and reduced sarcomere length, which contributed about equally to predicted dysfunction in the disarrayed myocardium. PMID:11454551

Usyk, T P; Omens, J H; McCulloch, A D

2001-08-01

352

Arc-Length-Based Axial Deformation and Length Preserving Deformation  

Microsoft Academic Search

This paper presents an arc-length preserving axial deformation along a B-spline curve based on arc-length parameterization of the axial curve. Space spanned by arc length and rotation minimizing frame on the axis is taken as the embedded space. As in real life, the length of an object's skeleton usually remains constant when it is axially deformed such as a swimming

Qunsheng Peng; Xiaogang Jin; Jieqing Feng

353

An empirical assessment of the focal species hypothesis.  

PubMed

Biodiversity surrogates and indicators are commonly used in conservation management. The focal species approach (FSA) is one method for identifying biodiversity surrogates, and it is underpinned by the hypothesis that management aimed at a particular focal species will confer protection on co-occurring species. This concept has been the subject of much debate, in part because the validity of the FSA has not been subject to detailed empirical assessment of the extent to which a given focal species actually co-occurs with other species in an assemblage. To address this knowledge gap, we used large-scale, long-term data sets of temperate woodland birds to select focal species associated with threatening processes such as habitat isolation and loss of key vegetation attributes. We quantified co-occurrence patterns among focal species, species in the wider bird assemblage, and species of conservation concern. Some, but not all, focal species were associated with high levels of species richness. One of our selected focal species was negatively associated with the occurrence of other species (i.e., it was an antisurrogate)-a previously undescribed property of nominated focal species. Furthermore, combinations of focal species were not associated with substantially elevated levels of bird species richness, relative to levels associated with individual species. Our results suggest that although there is some merit to the underpinning concept of the FSA, there is also a need to ensure that actions are sufficiently flexible because management tightly focused on a given focal species may not benefit some other species, including species of conservation concern, such of which might not occur in species-rich assemblages. Una Evaluación Empírica de la Hipótesis de Especie Focal. PMID:25048948

Lindenmayer, D B; Lane, P W; Westgate, M J; Crane, M; Michael, D; Okada, S; Barton, P S

2014-12-01

354

Selecting a high-power fiber-optic laser beam delivery system  

SciTech Connect

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.

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

355

RESEARCH Open Access Focal Laser Ablation of Prostate Cancer  

E-print Network

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

Paris-Sud XI, Université de

356

Effects of gender and estradiol treatment on focal brain ischemia  

Microsoft Academic Search

The present studies were undertaken to investigate the effects of gender and estrogen treatment on focal cerebral ischemia in male and female rats. Focal ischemia was created by inserting a 3-0 surgical suture through the left cervical internal carotid artery to obstruct the blood flow into the middle cerebral artery (MCA). The MCA was reperfused by removing the suture in

Yu-Qi Zhang; Jiong Shi; Gopal Rajakumar; Arthur L Day; James W Simpkins

1998-01-01

357

How Heterogeneous Stress Biases the Orientations of Focal Mechanisms  

Microsoft Academic Search

We explore the effect of spatially heterogeneous stress on standard focal mechanism inversions. We ask the following questions: Does the presence of spatially heterogeneous stress, coupled with a stress rate of a particular orientation, bias which points fail as earthquakes? If there is a bias to which points fail and are consequently included in focal mechanism inversions, then will inversions,

D. E. Smith; T. H. Heaton

2004-01-01

358

CONSTRAINTS ON CRUSTAL RHEOLOGY FROM EARTHQUAKE FOCAL MECHANISMS  

Microsoft Academic Search

The traction free boundary condition across the Earth's surface provides an opportunity for studying the relationship between stress orientation and earthquake focal mechanisms because it requires alignment of principal stress axes with vertical and horizontal orientations. A survey of focal mechanisms in northern California shows that their principal axes are also closely aligned with the vertical and the horizontal in

Götz H. R. Bokelmann; Gregory C. Beroza

359

An automated drug delivery system for focal epilepsy  

Microsoft Academic Search

Previous studies have demonstrated the ability to stop seizures in animal models with injection of antiepileptic medication directly onto the seizure focus. The present experiments describe automated detection and focal therapy for seizures in the laboratory setting. Focal seizures were created in Sprague–Dawley rats using bicuculline, a GABA antagonist. Computerized detection of seizures was linked to a programmable infusion pump

Alan G Stein; Hans G Eder; David E Blum; Alexander Drachev; Robert S Fisher

2000-01-01

360

Sonic boom focal zones due to tactical aircraft maneuvers  

Microsoft Academic Search

A study has been conducted of the focal zone 'superbooms' associated with tactical maneuvers of military supersonic aircraft. Focal zone footprints were computed for 21 tactical maneuvers: two for the SR-71 and 19 for fighters engaged in air combat maneuver (ACM) training. These footprints provide quantitative results which may be used for environmental planning. A key finding of this study

Kenneth J. Plotkin

1990-01-01

361

Focal Depth and Mechanism of Mid-Ocean Ridge Earthquakes  

Microsoft Academic Search

Rayleigh wave phase and amplitude spectra are used to determine the focal depths and mechanisms of mid-ocean ridge earthquakes. The effect of propagation on the spectra is removed by analyzing the differential phase and the amplitude ratio of the Rayleigh waves frompair of close events with different focal mechanisms. This analysis preserves the differ- ence between the source spectra. By

Donald J. Weidner; Keiiti Aki

1973-01-01

362

Electron beam deflected to determine focal point location  

NASA Technical Reports Server (NTRS)

System locates the focal point of an extremely high intensity electron beam. The electron beam is swept and scanned cyclically with deflection coils under a focusing lens, causing the beam focal point to move so the locus of its positions is a spherical surface symmetrical to the beam axis.

Downing, R. D.

1968-01-01

363

Image sensor with focal plane extraction of polarimetric information  

Microsoft Academic Search

Abstract—A novel ,focal plane imaging ,sensor capable of real ,time extraction of polarization ,information is presented. The imaging ,system consists of a photo array of 256 by 256 linear current mode ,active pixel sensors (APS). Analog ,processing circuitry is included ,at the focal plane for noise suppression and computation ,of the Stokes parameters. The imaging sensor was fabricated in TSMC

Viktor Gruev; Jan Van Der Spiegel; Nader Engheta

2006-01-01

364

Central Focal Interface Opacity After Laser in situ Keratomileusis  

Microsoft Academic Search

BACKGROUND: The acute onset of a focal cen- tral interface opacity with visual loss following LASIK has not been described in the peer reviewed literature. Non-peer reviewed reports of various inflammatory lesions have been recorded. METHODS: We describe three cases in which an acute focal stromal interface opacification was identified within 1 week of laser in situ ker- atomileusis (LASIK).

Graham E. Fraenkel; Peter R. Cohen; Gerard L. Sutton; Michael A. Lawless; Christopher M. Rogers

365

Mutations of DEPDC5 cause autosomal dominant focal epilepsies.  

PubMed

The main familial focal epilepsies are autosomal dominant nocturnal frontal lobe epilepsy, familial temporal lobe epilepsy and familial focal epilepsy with variable foci. A frameshift mutation in the DEPDC5 gene (encoding DEP domain-containing protein 5) was identified in a family with focal epilepsy with variable foci by linkage analysis and exome sequencing. Subsequent pyrosequencing of DEPDC5 in a cohort of 15 additional families with focal epilepsies identified 4 nonsense mutations and 1 missense mutation. Our findings provided evidence of frequent (37%) loss-of-function mutations in DEPDC5 associated with a broad spectrum of focal epilepsies. The implication of a DEP (Dishevelled, Egl-10 and Pleckstrin) domain-containing protein that may be involved in membrane trafficking and/or G protein signaling opens new avenues for research. PMID:23542701

Ishida, Saeko; Picard, Fabienne; Rudolf, Gabrielle; Noé, Eric; Achaz, Guillaume; Thomas, Pierre; Genton, Pierre; Mundwiller, Emeline; Wolff, Markus; Marescaux, Christian; Miles, Richard; Baulac, Michel; Hirsch, Edouard; Leguern, Eric; Baulac, Stéphanie

2013-05-01

366

Controllable parabolic lensed liquid-core optical fiber by using electrostatic force.  

PubMed

For typical optical fiber system, an external lens accessory set is required to adjust the optical path of output light, which however is limited by the fixed parameter of the lens accessory setup. Considering spherical aberration in the imaging process and its small focusable spot size, a complicated lens combination is required to compensate the aberration. This paper has demonstrated a unique method to fabricate liquid-core lensed fibers by filling water and NOA61 respectively into hollow Teflon AF fibers and silicate fiber, the radius of curvature of the liquid lens can be controlled by adjusting the applied voltage on the core liquid and even parabolic shape lens can be produced with enough applied voltage. The experiment has successfully demonstrated a variation of focal length from 0.628mm to 0.111mm responding to the change of applied voltage from 0V to 3.2KV (L = 2mm) for the Teflon AF fiber, as well as a variation of focal length from 0.274mm to 0.08mm responding to the change of applied voltage from 0V to 3KV (L = 2mm) for the silicate fiber. Further simulation shows that the focused spot size can be reduced to 2µm by adjusting the refractive index and fiber geometry. Solid state parabolic lensed fiber can be produced after NOA61 is solidified by the UV curing. PMID:25321295

Tang, Chun Yin; Zhang, Xuming; Chai, Yang; Hui, Long; Tao, Lili; Tsang, Yuen H

2014-08-25

367

Osteogenic lineage restriction by osteoprogenitors cultured on nanometric grooved surfaces: The role of focal adhesion maturation?  

PubMed Central

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

Cassidy, John W.; Roberts, Jemma N.; Smith, Carol-Anne; Robertson, Mary; White, Kate; Biggs, Manus J.; Oreffo, Richard O.C.; Dalby, Matthew J.

2014-01-01

368

918 OPTICS LETTERS / Vol. 27, No. 11 / June 1, 2002 Nonlinear effects in acousto-optic imaging  

E-print Network

of light and sound. Since the US beam usu- ally undergoes no scattering, the size of the detected crossed (; 45 mm; focal length, 60 mm; frequency, 3 MHz) the focal zone of the US beam is 1.5 cm long and 1.5 mm

Selb, Juliette

369

Adaptive Optics Communications Performance Analysis  

NASA Technical Reports Server (NTRS)

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.

Srinivasan, M.; Vilnrotter, V.; Troy, M.; Wilson, K.

2004-01-01

370

Mosaic near-infrared focal plane array  

NASA Astrophysics Data System (ADS)

To built a 3K X 3K pixel near-IR FPA, we have made a package and a multi-chip module for Mitsubishi 1040 X 1040 PtSi CSD, which is one of the largest SWIR FPAs. Mosaicing demands smallest gaps between chips to achieve a large fill-factor and controlled flatness to fit a camera focal plane. The package of 52-pin half-pitch PGA has been designed to be smaller than the bear chip. After the chip is glued on the package and wire-bonded, nine packages with the chip are arrayed in three by three on a multi chip module (MCM) of 6 cm X 6 cm area. The fill-factor of the imaging area is 89 percent. The package and MCM are made of AlN ceramic of high thermal conductivity. MCM, therefore, plays a role of an efficient heat sink. The surface of the package, with which the chip is in contact, has been polished with accurate flatness as well as MCM. As the result, the height of nine chips built on MCM are uniform within approximately 20 micrometers in 6 cm X 6 cm area. The mosaic array will be equipped in a near-IR camera for astronomical observations of a wide field view.

Ichikawa, Takashi; Itoh, Nobunari; Yanagisawa, Kenshi; Asai, Kenichirou; Shiraishi, Tadashi; Kimata, Masafumi

1998-08-01

371

Dynamic MEG imaging of focal neuronal sources  

SciTech Connect

We describe inverse methods for using the magnetoencephalogram (MEG) to image neural current sources associated with functional activation in the cerebral cortex. A Bayesian formulation is presented that is based on a Gibbs prior which reflects the sparse, focal nature of neural activation. The model includes a dynamic component so that we can utilize the full spatio-temporal data record to reconstruct a sequence of images reflecting changes in the current source amplitudes during activation. The model consists of the product of a binary field, representing the areas of activation in the cerebral cortex, and a time series at each site which represents the dynamic changes in the source amplitudes at the active sites. Our estimation methods are based on the optimization of three different functions of the posterior density. Each of these methods requires the estimation of a binary field which we compute using a mean field annealing method. We demonstrate and compare our methods in application to computer generated and experimental phantom data.

Phillips, J.W.; Leahy R.M. [Univ. of Southern California, Los Angeles, CA (United States); Mosher, J.C. [Los Alamos National Lab., NM (United States)

1996-12-31

372

Antenna-coupled infrared focal plane array  

NASA Astrophysics Data System (ADS)

In this dissertation a new type of infrared focal plane array (IR FPA) was investigated, consisting of antenna-coupled microbolometers fabricated using electron-beam lithography. Four different antenna designs were experimentally demonstrated at 10-micron wavelength: dipole, bowtie, square-spiral, and log-periodic. The main differences between these antenna types were their bandwidth, collection area, angular reception pattern, and polarization. To provide pixel collection areas commensurate with typical IR FPA requirements, two configurations were investigated: a two-dimensional serpentine interconnection of individual IR antennas, and a Fresnel-zone-plate (FZP) coupled to a single-element antenna. Optimum spacing conditions for the two-dimensional interconnect were developed. Increased sensitivity was demonstrated using a FZP-coupled design. In general, it was found that the configuration of the antenna substrate material was critical for optimization of sensitivity. The best results were obtained using thin membranes of silicon nitride to enhance the thermal isolation of the antenna-coupled bolometers. In addition, choice of the bolometer material was also important, with the best results obtained using vanadium oxide. Using optimum choices for all parameters, normalized sensitivity (D*) values in the range of mid 108 [cm Hz /W] were demonstrated for antenna-coupled IR sensors, and directions for further improvements were identified. Successful integration of antenna-coupled pixels with commercial readout integrated circuits was also demonstrated.

Gonzalez, Francisco Javier

373

Multiwavelength infrared focal plane array detector  

NASA Technical Reports Server (NTRS)

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.

Forrest, Stephen R. (Inventor); Olsen, Gregory H. (Inventor); Kim, Dong-Su (Inventor); Lange, Michael J. (Inventor)

1995-01-01

374

Kepler Mission's focal plane characterization models implementation  

NASA Astrophysics Data System (ADS)

The Kepler Mission photometer is an unusually complex array of CCDs. A large number of time-varying instrumental and systematic effects must be modeled and removed from the Kepler pixel data to produce light curves of sufficiently high quality for the mission to be successful in its planet-finding objective. After the launch of the spacecraft, many of these effects are difficult to remeasure frequently, and various interpolations over a small number of sample measurements must be used to determine the correct value of a given effect at different points in time. A library of software modules, called Focal Plane Characterization (FC) Models, is the element of the Kepler Science Data Pipeline (hereafter "pipeline") that handles this. FC, or products generated by FC, are used by nearly every element of the SOC processing chain. FC includes Java components: database persistence classes, operations classes, model classes, and data importers; and MATLAB code: model classes, interpolation methods, and wrapper functions. These classes, their interactions, and the database tables they represent, are discussed. This paper describes how these data and the FC software work together to provide the pipeline with the correct values to remove non-photometric effects caused by the photometer and its electronics from the Kepler light curves. The interpolation mathematics is reviewed, as well as the special case of the sky-to-pixel/pixel-to-sky coordinate transformation code, which incorporates a compound model that is unique in the SOC software.

Allen, Christopher; Klaus, Todd; Jenkins, Jon

2010-07-01

375

Coaxial atomizer liquid intact lengths  

NASA Technical Reports Server (NTRS)

Average intact lengths of round liquid jets generated by airblast coaxial atomizer were measured from over 1500 photographs. The intact lengths were studied over a jet Reynolds number range of 18,000 and Weber number range of 260. Results are presented for two different nozzle geometries. The intact lengths were found to be strongly dependent on Re and We numbers. An empirical equation was derived as a function of these parameters. A comparison of the intact lengths for round jets and flat sheets shows that round jets generate shorter intact lengths.

Eroglu, Hasan; Chigier, Norman; Farago, Zoltan

1991-01-01

376

Recording of incoherent reflective volume Fourier holograms for optical correlators  

NASA Astrophysics Data System (ADS)

The scheme of recording of reflective volume Fourier holograms in monochromatic light with partial spatial coherence is presented. The scheme contains posed on one optical axis an illuminated or self-luminous object, Fourier-objective, photosensitive medium and concave mirror. The light is proposed to be monochromatic with partial spatial coherence. The object is located in a front focal plane of the Fourier-objective. Photosensitive medium is placed in a back focal plane of the Fourier-objective, and the mirror is posed on a double focal length of the mirror from photosensitive medium. The light from input object is focused by the Fourier-objective in a volume of photosensitive medium, shaping a far field diffraction pattern of input object. This pattern is partial coherent analog of Fourier transform of input object. The light transmitted through the medium falls on the concave mirror and is reflected back, thus the mirror shapes the second copy of far field diffraction pattern of input object in the volume of photosensitive medium. Thus, these two light waves, propagating in the opposite directions, form the interference pattern in photosensitive medium, and a reflective volume Fourier hologram is recorded by monochromatic light with partial spatial coherence. The experiments on recording of these holograms and image reconstruction were realized. Patent by Russian Federation No2176099 on the device of recording of reflective volume holographic Fourier-filter in light with partial spatial coherence was taken out. Described reflective volume Fourier-holograms can be used in optical correlators as the spatial filters and spectral selectors at image recognition both in monochromatic and polychromatic light.

Rodin, Vladislav G.; Starikov, Sergey N.

2007-01-01

377

The Focal Adhesion: A Regulated Component of Aortic Stiffness  

PubMed Central

Increased aortic stiffness is an acknowledged predictor and cause of cardiovascular disease. The sources and mechanisms of vascular stiffness are not well understood, although the extracellular matrix (ECM) has been assumed to be a major component. We tested here the hypothesis that the focal adhesions (FAs) connecting the cortical cytoskeleton of vascular smooth muscle cells (VSMCs) to the matrix in the aortic wall are a component of aortic stiffness and that this component is dynamically regulated. First, we examined a model system in which magnetic tweezers could be used to monitor cellular cortical stiffness, serum-starved A7r5 aortic smooth muscle cells. Lysophosphatidic acid (LPA), an activator of myosin that increases cell contractility, increased cortical stiffness. A small molecule inhibitor of Src-dependent FA recycling, PP2, was found to significantly inhibit LPA-induced increases in cortical stiffness, as well as tension-induced increases in FA size. To directly test the applicability of these results to force and stiffness development at the level of vascular tissue, we monitored mouse aorta ring stiffness with small sinusoidal length oscillations during agonist-induced contraction. The alpha-agonist phenylephrine, which also increases myosin activation and contractility, increased tissue stress and stiffness in a PP2- and FAK inhibitor 14-attenuated manner. Subsequent phosphotyrosine screening and follow-up with phosphosite-specific antibodies confirmed that the effects of PP2 and FAK inhibitor 14 in vascular tissue involve FA proteins, including FAK, CAS, and paxillin. Thus, in the present study we identify, for the first time, the FA of the VSMC, in particular the FAK-Src signaling complex, as a significant subcellular regulator of aortic stiffness and stress. PMID:23626821

Saphirstein, Robert J.; Gao, Yuan Z.; Jensen, Mikkel H.; Gallant, Cynthia M.; Vetterkind, Susanne; Moore, Jeffrey R.; Morgan, Kathleen G.

2013-01-01

378

Pars plana vitrectomy combined with focal endolaser photocoagulation for idiopathic macular telangiectasia.  

PubMed

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

Terauchi, Gaku; Matsumoto, Celso Soiti; Shinoda, Kei; Matsumoto, Harue; Imamura, Yutaka; Watanabe, Emiko; Kondo, Takaaki; Mizota, Atsushi

2014-01-01

379

Pars Plana Vitrectomy Combined with Focal Endolaser Photocoagulation for Idiopathic Macular Telangiectasia  

PubMed Central

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

Terauchi, Gaku; Matsumoto, Celso Soiti; Shinoda, Kei; Matsumoto, Harue; Imamura, Yutaka; Watanabe, Emiko; Kondo, Takaaki; Mizota, Atsushi

2014-01-01

380

Semiconductor detectors and focal plane arrays for far-infrared imaging  

NASA Astrophysics Data System (ADS)

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.

Rogalski, A.

2013-12-01

381

Focal plane resolution and overlapped array time delay and integrate imaging  

NASA Astrophysics Data System (ADS)

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.

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

2010-06-01

382

Fiber optic temperature sensor  

NASA Technical Reports Server (NTRS)

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.

Sawatari, Takeo (Inventor); Gaubis, Philip A. (Inventor); Mattes, Brenton L. (Inventor); Charnetski, Clark J. (Inventor)

1999-01-01

383

Focal spot measurements using a digital flat panel detector  

PubMed Central

Focal spot size is one of the crucial factors that affect the image quality of any x-ray imaging system. It is, therefore, important to measure the focal spot size accurately. In the past, pinhole and slit measurements of x-ray focal spots were obtained using direct exposure film. At present, digital detectors are replacing film in medical imaging so that, although focal spot measurements can be made quickly with such detectors, one must be careful to account for the generally poorer spatial resolution of the detector and the limited usable magnification. For this study, the focal spots of a diagnostic x-ray tube were measured with a 10-?m pinhole using a 194-?m pixel flat panel detector (FPD). The two-dimensional MTF, measured with the Noise Response (NR) Method was used for the correction for the detector blurring. The resulting focal spot sizes based on the FWTM (Full Width at Tenth Maxima) were compared with those obtained with a very high resolution detector with 8-?m pixels. This study demonstrates the possible effect of detector blurring on the focal spot size measurements with digital detectors with poor resolution and the improvement obtained by deconvolution. Additionally, using the NR method for measuring the two-dimensional MTF, any non-isotropies in detector resolution can be accurately corrected for, enabling routine measurement of non-isotropic x-ray focal spots. This work presents a simple, accurate and quick quality assurance procedure for measurements of both digital detector properties and x-ray focal spot size and distribution in modern x-ray imaging systems.

Jain, Amit; Panse, A.; Bednarek, Daniel R.; Rudin, Stephen

2014-01-01

384

Focal spot measurements using a digital flat panel detector  

NASA Astrophysics Data System (ADS)

Focal spot size is one of the crucial factors that affect the image quality of any x-ray imaging system. It is, therefore, important to measure the focal spot size accurately. In the past, pinhole and slit measurements of x-ray focal spots were obtained using direct exposure film. At present, digital detectors are replacing film in medical imaging so that, although focal spot measurements can be made quickly with such detectors, one must be careful to account for the generally poorer spatial resolution of the detector and the limited usable magnification. For this study, the focal spots of a diagnostic x-ray tube were measured with a 10-?m pinhole using a 194-?m pixel flat panel detector (FPD). The twodimensional MTF, measured with the Noise Response (NR) Method was used for the correction for the detector blurring. The resulting focal spot sizes based on the FWTM (Full Width at Tenth Maxima) were compared with those obtained with a very high resolution detector with 8-?m pixels. This study demonstrates the possible effect of detector blurring on the focal spot size measurements with digital detectors with poor resolution and the improvement obtained by deconvolution. Additionally, using the NR method for measuring the two-dimensional MTF, any non-isotropies in detector resolution can be accurately corrected for, enabling routine measurement of non-isotropic x-ray focal spots. This work presents a simple, accurate and quick quality assurance procedure for measurements of both digital detector properties and x-ray focal spot size and distribution in modern x-ray imaging systems.

Jain, Amit; Panse, A.; Bednarek, Daniel R.; Rudin, Stephen

2014-03-01

385

Recovery of Deep Moonquake Focal Mechanisms  

NASA Technical Reports Server (NTRS)

Deep moonquakes are clustered not only in space but also in time: their recurrence times correspond to the durations of the anomalistic and draconic months, with some clusters preferring one of the two periods, while others are active with both periods. A key constraint for the understanding of the connection between the orbital motion of the Moon and its seismic activity is the focal mechanism: the orientation of the fault surface on which failure occurs during the quake. Due to the small aperture of the Apollo seismic network and the strong scattering of seismic waves within the lunar crust, the evaluation of P wave first motions to constrain the strike and dip of the fault planes is not feasible. Instead we evaluate the amplitude ratios of P and S waves. Seismograms are rotated into the P-SV-SH coordinate frame and amplitudes are determined as averages over short time windows after the arrival to reduce the impact of the scattering coda, which is independent of the source orientation. We allow for reversals of the fault motion, as observed for some clusters in previous studies, by taking into account the absolute amplitude only, without sign. An empirical site correction factor is applied to correct for amplitude distortions in the crust. We construct ensembles of fault plane solutions using an exhaustive grid search by accepting all orientations that reproduce the measured amplitude ratios within the observed standard deviations. Since all events of a given cluster are supposed to share the same fault plane, the combination of the individual inversion results further constrains the orientation. We evaluate 106 events from 25 different moonquake clusters. The most active cluster A001 contributes 37 events, while others contribute 1 to 9 events per cluster. Comparison of fault orientations with the variation of the tidal stress results in preferred orientations.

Weber, Renee C.; Knapmeyer, Martin

2012-01-01

386

Rebouissou et al 1 Molecular pathogenesis of focal nodular hyperplasia and  

E-print Network

Rebouissou et al 1 Molecular pathogenesis of focal nodular hyperplasia and hepatocellular adenoma@cephb.fr Key Words: Hepatocellular adenoma, focal nodular hyperplasia, chromosome, gene mutation, hepatocyte adenomatous polyposis coli) FNH (focal nodular hyperplasia) HCA (hepatocellular adenoma) HCC (hepatocellular

Paris-Sud XI, Université de

387

Focal Laser Photocoagulation in Non-Center Involved Diabetic Macular Edema  

PubMed Central

This study was performed to evaluate the functional and anatomic outcomes of focal macular laser photocoagulation in eyes with non-center involved macular edema (non-CI ME). Forty-nine eyes of 43 patients with non-CI ME were included. Focal macular laser photocoagulation was conducted on twenty-nine eyes of 25 patients, while 20 eyes of 18 patients with non-CI ME were followed without treatment and served as the control group. Data relating to best corrected visual acuity (BCVA; Early Treatment Diabetic Retinopathy Study) and central subfield thickness (CST), inner zone thickness (IZT), outer zone thickness (OZT), and total macular volume (TMV) as determined by optical coherence tomography (OCT) were collected and compared between the groups. At 12 months, VA decreased by a mean of 0.4 letters in the treatment group and 3.3 letters in the control group (p=0.03). Gain in VA ?5 letters was noted in 6 (21%) of the eyes in the treatment group versus 1 (5%) eye in the control group (p=0.12). At 12 months, average IZT decreased by 22.6 microns in the treatment group and increased by 10.9 microns in the control group (p<0.001). The treatment group revealed significant reduction in CST, average OZT, and TMV as compared to the control group at 12 months (all p<0.05).Generally, focal laser photocoagulation may have more favourable visual outcomes in this specific group of diabetic patients than does observation. In addition, focal laser treatment provided better outcomes with improvement in OCT parameters as compared to the control group. PMID:24804275

Perente, Irfan; Alkin, Zeynep; Ozkaya, Abdullah; Dardabounis, Doukas; Ogreden, Tulin Aras; Konstantinidis, Aristeidis; Kyratzoglou, Konstantinos; Yazici, Ahmet Taylan

2014-01-01

388

Towards a comprehensive eye model for zebrafish retinal imaging using full range spectral domain optical coherence tomography  

NASA Astrophysics Data System (ADS)

In regenerative medicine, the zebrafish is a prominent animal model for studying degeneration and regeneration processes, e.g. of photoreceptor cells in the retina. By means of optical coherence tomography (OCT), these studies can be conducted over weeks using the same individual and hence reducing the variability of the results. To allow an improvement of zebrafish retinal OCT imaging by suitable optics, we developed a zebrafish eye model using geometrical data obtained by in vivo dispersion encoded full range OCT as well as a dispersion comprising gradient index (GRIN) lens model based on refractive index data found in the literature. Using non-sequential ray tracing, the focal length of the spherical GRIN lens (diameter of 0.96 mm) was determined to be 1.22 mm at 800 nm wavelength giving a Matheissen's ratio (ratio of focal length to radius of the lens) of 2.54, which fits well into the range between 2.19 and 2.82, found for various fish lenses. Additionally, a mean refractive index of 1.64 at 800 nm could be retrieved for the lens to yield the same focal position as found for the GRIN condition. With the aid of the zebrafish eye model, the optics of the OCT scanner head were adjusted to provide high-resolution retinal images with a field of view of 30° x 30°. The introduced model therefore provides the basis for improved retinal imaging with OCT and can be further used to study the image formation within the zebrafish eye.

Gaertner, Maria; Weber, Anke; Cimalla, Peter; Köttig, Felix; Brand, Michael; Koch, Edmund

2014-03-01

389

Tunable liquid optics: electrowetting-controlled liquid mirrors based on self-assembled Janus tiles  

NASA Astrophysics Data System (ADS)

In this work we describe a tunable, high-reflectivity optofluidic device based on self-assembly of anisotropically-functionalized hexagonal micromirrors (Janus tiles) on the surface of an oil droplet to create a concave liquid mirror. The liquid mirror is deposited on a patterned transparent electrode that allows the focal length and axial position to be electrically controlled. The mirror is mechanically robust and retains its integrity even at high levels of vibrational excitation of the interface. The use of reflection instead of refraction overcomes the limited available refractive-index contrast between pairs of density-matched liquids, allowing stronger focusing than is possible for a liquid lens of the same geometry. This approach is compatible with optical instruments that could provide novel functionality - for example, a dynamic 3D projector; i.e., a light source which can scan an image onto a moving, non-planar focal surface. Janus tiles with complex optical properties can be manufactured using our approach, thus potentially enabling a wide range of novel optical elements.

Krupenkin, Tom; Bucaro, Mike; Kolodner, Paul; Taylor, Ashley; Sidorenko, Alex; Aizenberg, Joanna

2009-03-01

390

Tunable liquid optics: electrowetting-controlled liquid mirrors based on self-assembled Janus tiles.  

PubMed

In this paper, we describe a tunable, high-reflectivity optofluidic device based on self-assembly of anisotropically functionalized hexagonal micromirrors (Janus tiles) on the surface of an oil droplet to create a concave liquid mirror. The liquid mirror is deposited on a patterned transparent electrode that allows the focal length and axial position to be electrically controlled. The mirror is mechanically robust and retains its integrity even at high levels of vibrational excitation of the interface. The use of reflection instead of refraction overcomes the limited available refractive-index contrast between pairs of density-matched liquids, allowing stronger focusing than is possible for a liquid lens of the same geometry. This approach is compatible with optical instruments that could provide novel functionality-for example, a dynamic 3D projector, i.e., a light source which can scan an image onto a moving, nonplanar focal surface. Janus tiles with complex optical properties can be manufactured using our approach, thus potentially enabling a wide range of novel optical elements. PMID:19708158

Bucaro, Michael A; Kolodner, Paul R; Taylor, J Ashley; Sidorenko, Alex; Aizenberg, Joanna; Krupenkin, Tom N

2009-04-01

391

Design of apochromatic telescopic optical system based on PWC method  

NASA Astrophysics Data System (ADS)

According to technical requirements,an apochromatic telescopic optical system which is characterized by the focal length 1.5m~2m,with the visible region spectrum band is needed.The successful design consists in using normal glasses based on PWC method to get a completely secondary-spectrum-removed and cramped construction telescopic optical system in this paper.Firstly, by the aberration theory and ZEMAX optical design software,a catadioptric achromatic optical system composed of a reflecting mirror and a couple of air-spaced negative doublets are designed.The initial configuration of optical system is calculated by PWC method and the proper couple of air-spaced negative doublets are chosen by the theory of achromatic.By comparing with various optical systems with different couple of air-spaced negative doublets, it is found that the combination of the heavy crown glass ZK7 and heavy flint glass ZF3 is effective to correct chromatic aberration and its secondary spectrum value is minimality.It can conclude that fact with the abbe number of ZK7 is twice than ZF3 make the good result and give guiding to the design of the same type of optical system. Secondary,according to the theory of secondary spectrum,the secondary spectrum value to be corrected is analyzed and the compensation can be changed by adjust the magnification power.The comparison is presented and the final telescopic optical system with cramped construction is achieved, and the goal of apochromatism and other aberration is reached.

Wei, Xiao-Xiao; Xu, Feng; Yu, Jian-jun

2011-11-01

392

Factory acceptance test results for the DIRSP projection optics  

NASA Astrophysics Data System (ADS)

The Factory Acceptance Test (FAT) results for the projection optical subsystem (POS) of US Army STIRCOM's dynamic infrared scene projector (DIRSP) are presented in this paper. DIRSP is a low background (-35 degrees Celsius) hardware-in-the- loop (HWIL), long-wave infrared (LWIR) scene projector built by Mission Research Corporation (MRC) for use by the Redstone Technical Test Center (RTTC). It has an effective emitter array size of 1632 X 672 suspended-membrane micro-resistor elements. The POS is responsible for generating this effective array size from three smaller arrays using a mosaic image combiner, adding background light from an external blackbody, and collimating the combined radiation with a 5:1 vacuum enclosed -35 degree Celsius zoom lens. The FAT results reported demonstrate good POS performance compared to the design for focal length, F/#, MTF and apparent temperature.

Thomas, Matthew C.; Ward, Craig S.

2000-07-01

393

Fast optical spectrometer for the charge exchange diagnostic on RFX-mod  

SciTech Connect

A new fast visible spectrometer built for the charge exchange diagnostic system of the RFX-mod Reversed Field pinch experiment is described. The optical mounting is of the Littrow type. The spectral resolution is defined by a 3000 grooves/mm, 180x143 mm{sup 2} wide reflection grating, and a focal length of 400 mm. The collimating optics is based on a commercial high quality f/2.8 telephoto lens, so that the input fibers can be vertically stacked without space in between. The detector is a two-dimensional charge coupled device back-illuminated sensor to ensure high quantum efficiency. Thus the spectrometer combines high speed, high spectral resolution, and excellent imaging quality.

Gazza, E.; Valisa, M. [Consorzio RFX, Associazione Euratom-ENEA sulla fusione, 35127 Padova (Italy)

2009-03-15

394

An adaptive algorithm for strongly chirped pulses propagating in optical fibers  

NASA Astrophysics Data System (ADS)

Chirp, especially strong chirp, can be used to control the pulses in optical fibers, but it makes numerical simulation difficult by using the time-domain beam propagation method (TD-BPM) because of more sampling data requirements. In this paper, we present a modified beam propagation method (M-BPM) to efficiently simulate the propagation of strongly chirped pulses along an optical fiber. The validity of the M-BPM is demonstrated both theoretically and numerically. Numerical simulations show that the number of samples in time necessary to simulate the chirped pulse propagation by the TD-BPM varies linearly with the initial chirp parameter, but that of the M-BPM is the same one would need to simulate the propagation of the envelope without the initial chirp. In addition, the closer the propagation distance is to the temporal focal length, the more efficient the M-BPM comparing with the TD-BPM is.

Wu, Lianglong; Fu, Xiquan; Guo, Xing; Li, Huai

2012-07-01

395

Achromatic optical Fourier transformer with planar-integrated free-space optics  

E-print Network

These microlenses are concave mirrors with a constant image focal length for all the wave- lengths of the source. Therefore these elements are well adapted to broadband imaging purposes. How- ever, even if only DOEs-light holographic doublet was pro- posed to reconstruct three-dimensional images. In the latter case the spectral

Jahns, Jürgen

396

A Randomized Trial of Peribulbar Triamcinolone Acetonide with and without Focal Photocoagulation for Mild Diabetic Macular Edema: A Pilot Study  

PubMed Central

Objective To provide pilot data on the safety and efficacy of anterior and posterior subtenon's injections of triamcinolone either alone or in combination with focal photocoagulation in the treatment of mild diabetic macular edema (DME). Design Prospective phase 2 multi-center randomized clinical trial. Participants 109 patients (129 eyes) with mild diabetic macular edema and visual acuity 20/40 or better. Methods The participants were randomly assigned to receive either focal photocoagulation (N = 38), 20 mg anterior subtenon's injection of triamcinolone (N = 23), 20 mg anterior subtenon's injection followed by focal photocoagulation after 4 weeks (N = 25), 40 mg posterior subtenon's injection of triamcinolone (N = 21), or 40 mg posterior subtenon's injection followed by focal photocoagulation after 4 weeks (N = 22). Follow-up visits were performed at 4, 8, 17, and 34 weeks. Main Outcome Measures Change in visual acuity and retinal thickness measured with the Optical Coherence Tomography (OCT). Results At baseline, mean visual acuity in the study eyes was 20/25 and mean OCT central subfield thickness was 328 microns. Changes in retinal thickening and in visual acuity were not significantly different among the five groups at 34 weeks (P=0.46 and P=0.94, respectively). There was a suggestion of a greater proportion of eyes having a central subfield thickness < 250 microns at 17 weeks when the peribulbar triamcinolone was combined with focal photocoagulation. Elevated intraocular pressure and ptosis were adverse effects attributable to the injections. Conclusion In cases of DME with good visual acuity, peribulbar triamcinolone, with or without focal photocoagulation, is unlikely to be of substantial benefit. Based on these results, a phase 3 trial to evaluate the benefit of these treatments for mild DME is not warranted. PMID:17544778

2008-01-01

397

Spreading Depression in Focal Ischemia: A Computational Study  

E-print Network

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

Ruppin, Eytan

398

Mechanical design and analysis of focal plate for gravity deformation  

NASA Astrophysics Data System (ADS)

The surface accuracy of astronomical telescope focal plate is a key indicator to precision stellar observation. To conduct accurate deformation measurement for focal plate in different status, a 6-DOF hexapod platform was used for attitude adjustment. For the small adjustment range of a classic 6-DOF hexapod platform, an improved structural arrangement method was proposed in the paper to achieve ultimate adjustment of the focal plate in horizontal and vertical direction. To validate the feasibility of this method, an angle change model which used ball hinge was set up for the movement and base plate. Simulation results in MATLAB suggested that the ball hinge angle change of movement and base plate is within the range of the limiting angle in the process of the platform plate adjusting to ultimate attitude. The proposed method has some guiding significance for accurate surface measurement of focal plate.

Wang, Jianping; Chu, Jiaru; Hu, Hongzhuan; Li, Kexuan; Zhou, Zengxiang

2014-07-01

399

Stress Orientation Confidence Intervals from Focal Mechanism Inversion  

E-print Network

The determination of confidence intervals of stress orientation is a crucial element in the discussion of homogeneity or heterogeneity of the stress field under study. The error estimates provided by the grid search method Focal Mechanism Stress Inversion of Gephart and Forsyth (1984) have been shown to be too wide but the reasons for this failure have escaped elucidation. Through the use of directional statistics and synthetic focal mechanisms, I show that the grid search methodology does yield appropriate uncertainty estimates. The direct perturbation of the synthetic focal mechanisms introduces bias which leads to confidence intervals which become increasingly too wide as the amount of perturbation increases. The synthetic data also show at what point the method fails to overcome this bias and when confidence intervals will be too wide. The indirect perturbation of the focal mechanisms by perturbing the generating deviatoric stress tensor generates synthetic data devoid of bias. Inversion of these data set...

Revets, Stefan A

2010-01-01

400

Quantitative multi-modal analysis of pediatric focal epilepsy  

E-print Network

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 ...

Eow, Andy Khai Siang

2005-01-01

401

Real-time focal stack compositing for handheld mobile cameras  

NASA Astrophysics Data System (ADS)

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.

Solh, Mashhour

2013-03-01

402

SUSTAINED FOCAL CORTICAL COMPRESSION REDUCES ELECTRICALLY-INDUCED SEIZURE THRESHOLD  

E-print Network

cortical compres- sion on electrically-induced localized seizure threshold in rats. Male Long Evans rats depression, ex- citation and inhibition. Focal cortical compression can be a significant problem following

403

Focal osteoporotic bone marrow defect in the anterior maxilla.  

PubMed

An unusual presentation of a focal osteoporotic bone marrow defect is documented. A definitive diagnosis could not be established on the basis of the location, history, clinical, and radiographic appearance. A biopsy provided the identity of the lesion. PMID:8233438

Gordy, F M; Crews, K M; O Carroll, M K

1993-10-01

404

Compact Focal Plane Assembly for Planetary Science  

NASA Technical Reports Server (NTRS)

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.

Brown, Ari; Aslam, Shahid; Huang, Wei-Chung; Steptoe-Jackson, Rosalind

2013-01-01

405

Shock wave response of materials at different length scales  

SciTech Connect

After a brief introduction to shock wave propagation in solids, recent experimental developments to understand the real time response of shocked materials at various length scales are outlined. Results from two representative studies are summarized: x-ray diffraction to examine elastic-plastic deformation in shocked LiF crystals; and picosecond optical absorption to examine structural transformation in shocked CdS crystals. Issues related to examining material processes at different length scales in shock wave experiments are discussed briefly.

Gupta, Y.M.

1999-07-01

406

Dizygotic twins with schizencephaly and focal cortical dysplasia.  

PubMed

The case reports of 17-year-old female dizygotic twins are presented. One of the twins had bilateral closed-lip schizencephaly, and the other had focal cortical dysplasia. Septum pellucidum was absent in both cases. The cortical dysplasia in case 2 corresponded to the same hemispheric location with the right schizencephalic cleft in case 1. The combination of schizencephaly and focal cortical dysplasia in siblings or twins has not been previously reported. PMID:11003289

Senol, U; Karaali, K; Aktekin, B; Yilmaz, S; Sindel, T

2000-09-01

407

Difference between focal mechanisms of Dayao earthquake doublet sequence  

Microsoft Academic Search

Using the maximum amplitude ratios of vertical component of P and S waves recorded by a regional network, 921 focal mechanisms\\u000a of Dayao earthquake doublet sequence are determined by means of synthetic seismograms of a point source of dislocation in\\u000a a plane layered medium. Among them, 389 focal mechanisms are in the aftershock sequence of M6.2 earthquake occurred on 21

Xiaoshan Wang; Xiangdong Feng; Guiling Diao; Libing Wang; Lingling Cai

2009-01-01

408

Exploiting focal points among alternative solutions: Two approaches  

Microsoft Academic Search

Focal points refer to prominent solutions of an interaction, solutions to which agents are drawn. This paper considers how\\u000a automated agents could use focal points for coordination in communication?impoverished situations. Coordination is a central\\u000a theme of Distributed Artificial Intelligence. Much work in this field can be seen as a search for mechanisms that allow agents\\u000a with differing knowledge and goals

Sarit Kraus; Jeffrey S. Rosenschein; Maier Fenster

2000-01-01

409

Inflammatory pancreatic masses: problems in differentiating focal pancreatitis from carcinoma  

SciTech Connect

The authors studied 19 patients with focal inflammatory masses of the pancreas over an 18-month period. In 13 cases, transhepatic cholangiography and/or endoscopic retrograde cholangiopancreatography were unsuccessful in differentiating pancreatitis from carcinoma. Eighteen patients had a history of alcohol abuse, and 12 had had pancreatitis previously. Pre-existing glandular injury appears to be a prerequisite to formation of focal inflammatory pancreatic masses.

Neff, C.C.; Simeone, J.F.; Wittenberg, J.; Mueller, P.R.; Ferrucci, J.T. Jr.

1984-01-01

410

The dispersion-focalization theory of sound systems  

Microsoft Academic Search

The Dispersion-Focalization Theory states that sound systems in human languages are shaped by two major perceptual constraints: dispersion driving auditory contrast towards maximal or sufficient values [B. Lindblom, J. Phonetics 18, 135-152 (1990)] and focalization driving auditory spectra towards patterns with close neighboring formants. Dispersion is computed from the sum of the inverse squared inter-spectra distances in the (F1, F2,

Jean-Luc Schwartz; Christian Abry; Louis-Jean Boë; Nathalie Vallée; Lucie Ménard

2005-01-01

411

The Length of My Feet  

NSDL National Science Digital Library

This is Lesson 1 of a five lesson unit. "This lesson focuses students' attention on the attributes of length and develops their knowledge of and skill in using nonstandard units of measurement, their feet. It provides practice with and remediation of the measurable attributes of length." (from NCTM Illuminations)

Math, Illuminations N.

2009-01-28

412

Magnetic resonance imaging of radiation optic neuropathy  

SciTech Connect

Three patients with delayed radiation optic neuropathy after radiation therapy for parasellar neoplasms underwent magnetic resonance imaging. The affected optic nerves and chiasms showed enlargement and focal gadopentetate dimeglumine enhancement. The magnetic resonance imaging technique effectively detected and defined anterior visual pathway changes of radionecrosis and excluded the clinical possibility of visual loss because of tumor recurrence.

Zimmerman, C.F.; Schatz, N.J.; Glaser, J.S. (Univ. of Miami, FL (USA))

1990-10-15

413

Thermomechanical architecture of the VIS focal plane for Euclid  

NASA Astrophysics Data System (ADS)

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.

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

414

Optic communication and sensor systems  

Microsoft Academic Search

Development of an optic serial data system along with a set of passive optic sensor systems that are suitable for use in turbine engine controls will be discussed. Component development covered includes electro-optic interfaces, custom digital GaAs IC circuit design and custom silicon IC design. The passive optic sensor systems include wavelength division multiplexed displacement sensors, short coherence length interferometric

E. M. Arnett; S. M. Emo; T. R. Kinney

1988-01-01

415

MicroSight Optics  

SciTech Connect

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.

None

2010-01-01

416

MicroSight Optics  

ScienceCinema

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.

None

2013-05-28

417

Multiple pass reimaging optical system  

NASA Technical Reports Server (NTRS)

An optical imaging system for enabling nonabsorbed light imaged onto a photodetective surface to be collected and reimaged one or more times onto that surface in register with the original image. The system includes an objective lens, one or more imaging lenses, one or more retroreflectors and perhaps a prism for providing optical matching of the imaging lens focal planes to the photo detective surface.

Gunter, W. D., Jr.; Brown, R. M. (inventors)

1973-01-01

418

Three-dimensional shape-controllable focal spot array created by focusing vortex beams modulated by multi-value pure-phase grating.  

PubMed

We propose a method for creating a three-dimensional (3D) shape-controllable focal spot array by combination of a two-dimensional (2D) pure-phase modulation grating and an additional axial shifting pure-phase modulation composed of four-quadrant phase distribution unit at the back aperture of a high numerical aperture (NA) objective. It is demonstrated that the one-dimensional (1D) grating designed by optimized algorithm of selected number of equally spaced arbitrary phase value in a single period could produce desired number of equally spaced diffraction spot with identical intensity. It is also shown that the 2D pure-phase grating designed with this method could generate 2D diffraction spot array. The number of the spots in the array along each of two dimensions depends solely on the number of divided area with different phase values of the dimension. We also show that, by combining the axial translation phase modulation at the back aperture, we can create 3D focal spot array at the focal volume of the high NA objective. Furthermore, the shape or intensity distribution of each focal spot in the 3D focal array can be manipulated by introducing spatially shifted multi vortex beams as the incident beam. These kinds of 3D shape-controllable focal spot array could be utilized in the fabrication of artificial metamaterials, in parallel optical micromanipulation and multifocal multiphoton microscopic imaging. PMID:25321514

Zhu, Linwei; Sun, Meiyu; Zhu, Mengjun; Chen, Jiannong; Gao, Xiumin; Ma, Wangzi; Zhang, Dawei

2014-09-01

419

Thermally induced changes in the focal distance of composite mirrors - Composites with a zero coefficient of thermal expansion of the radius of curvature  

NASA Technical Reports Server (NTRS)

Calculations are presented of the coefficient of thermal expansion (CTE) of the radius of curvature of the reflector face sheets made of a quasi-isotropic composite. It is shown that, upon cooling, the change of the CTE of the focal distance of the mirror is equal to that of the radius of the curvature of the reflector face sheet. The CTE of the radius of the curvature of a quasi-isotropic composite face sheet depends on both the in-plane and the out-of-plane CTEs. The zero in-plane CTE of a face sheet does not guarantee mirrors with no focal length changes.

Dolgin, Benjamin P.

1992-01-01

420

Nd3+ doped CAS glasses: A thermo-optical and spectroscopic investigation  

NASA Astrophysics Data System (ADS)

Previous works have showed that calcium aluminosilicate (CAS) glasses, when prepared under vacuum conditions, are good candidates for solid state laser medium hosts and optical devices due to their appropriated thermal, optical and mechanical properties. These promising results led us to investigate the thermo-optical properties and emission spectra as a function of temperature in Nd3+ doped CAS glasses. Temperature changes in optical systems can cause structural modifications to the host, as well as other effects, such as emission quenching, or self-focalization. In this work, two series of CAS glasses, doped up to 5 wt.% Nd2O3, were prepared and characterized. Measurements of thermal coefficient of optical path length (dS/dT) and emission were performed on both series of Nd3+ doped CAS. In addition, measurements of optical absorption coefficient and emission lifetime were carried out. The results are discussed in terms of temperature dependence of these properties and Nd2O3 content. Comparisons with other glasses, such as LSCAS (low-silica calcium aluminosilicate) are also presented.

Steimacher, A.; Barboza, M. J.; Pedrochi, F.; Astrath, N. G. C.; Rohling, J. H.; Baesso, M. L.; Medina, A. N.

2014-11-01

421

Differences in lens optical plasticity in two gadoid fishes meeting in the Arctic.  

PubMed

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

Jönsson, Mikael; Varpe, Oystein; Koz?owski, Tomasz; Berge, Jørgen; Kröger, Ronald H H

2014-11-01

422

Remodeling of the axon initial segment after focal cortical and white matter stroke  

PubMed Central

BACKGROUND AND PURPOSE Recovery from stroke requires neuroplasticity within surviving adjacent cortex. The axon initial segment (AIS) is the site of action potential initiation and a focal point for tuning of neuronal excitability. Remodeling of the AIS may be important to neuroplasticity after stroke. METHODS Focal cortical stroke in forelimb motor cortex was induced by photothrombosis and compared to sham controls. White matter stroke was produced through stereotactic injection of a vasoconstrictor together with biotinylated dextran amine to retrogradely label injured cortical neurons. AIS length, morphology and number were measured using immunofluorescence and confocal microscopy two weeks after stroke. RESULTS Within the peri-infarct cortex and after white matter stroke, AIS length decreases. This shortening is accompanied by altered AIS morphology. In peri-infarct cortex, the decrease in AIS length after stroke occurs from the distal end of the AIS resulting in a loss of NaV1.6 channels. GABAR-?2 subunit staining at axoaxonic synapses along the AIS is significantly decreased. In addition, a significant increase in small, immature initial segments is present in layers 2/3 of peri-infarct cortex, reflecting maturation of axonal sprouting and new initial segments from surviving neurons. CONCLUSIONS Stroke alters the compartmental morphology of surviving adjacent neurons in peri-infarct cortex and in neurons whose distal axons are injured by white matter stroke. With a key role in modulation of neuronal excitability, these changes at the AIS may contribute to altered neuronal excitability after injury and prove crucial to increasing neuroplasticity in surviving tissue affected by stroke. PMID:23233385

Hinman, Jason D.; Rasband, Matthew N.; Carmichael, S. Thomas

2014-01-01

423

Optical tweezers for confocal microscopy  

NASA Astrophysics Data System (ADS)

In confocal laser scanning microscopes (CLSMs), lasers can be used for image formation as well as tools for the manipulation of microscopic objects. In the latter case, in addition to the imaging lasers, the light of an extra laser has to be focused into the object plane of the CLSM, for example as optical tweezers. Imaging as well as trapping by optical tweezers can be done using the same objective lens. In this case, z-sectioning for 3D imaging shifts the optical tweezers with the focal plane of the objective along the optical axis, so that a trapped object remains positioned in the focal plane. Consequently, 3D imaging of trapped objects is impossible without further measures. We present an experimental set-up keeping the axial trapping position of the optical tweezers at its intended position whilst the focal plane can be axially shifted over a distance of about 15 ?m. It is based on fast-moving correctional optics synchronized with the objective movement. First examples of application are the 3D imaging of chloroplasts of Elodea densa (Canadian waterweed) in a vigorous cytoplasmic streaming and the displacement of zymogen granules in pancreatic cancer cells (AR42 J).

Hoffmann, A.; Meyer zu Hörste, G.; Pilarczyk, G.; Monajembashi, S.; Uhl, V.; Greulich, K. O.

2000-11-01

424

Design of the Subaru laser guide star adaptive optics module  

Microsoft Academic Search

The laser guide star adaptive optics (AO) module for the Subaru Telescope will be installed at the f\\/13.9 IR Nasmyth focus, and provides the compensated image for the science instrument without change of the focal ratio. The optical components are mounted on an optical bench, and the flexure depending on the telescope pointing is eliminated. The transferred field of view

Makoto Watanabe; Hideki Takami; Naruhisa Takato; Stephen Colley; Michael Eldred; Thomas Kane; Olivier Guyon; Masayuki Hattori; Miwa Goto; Masanori Iye; Yutaka Hayano; Yukiko Kamata; Nobuo Arimoto; Naoto Kobayashi; Yosuke Minowa

2004-01-01

425

Fiber optic vibration sensor  

DOEpatents

A fiber optic vibration sensor utilizes two single mode optical fibers supported by a housing with one optical fiber fixedly secured to the housing and providing a reference signal and the other optical fiber having a free span length subject to vibrational displacement thereof with respect to the housing and the first optical fiber for providing a signal indicative of a measurement of any perturbation of the sensor. Damping or tailoring of the sensor to be responsive to selected levels of perturbation is provided by altering the diameter of optical fibers or by immersing at least a portion of the free span length of the vibration sensing optical fiber into a liquid of a selected viscosity. 2 figures.

Dooley, J.B.; Muhs, J.D.; Tobin, K.W.

1995-01-10

426

Fiber optic vibration sensor  

DOEpatents

A fiber optic vibration sensor utilizes two single mode optical fibers supported by a housing with one optical fiber fixedly secured to the housing and providing a reference signal and the other optical fiber having a free span length subject to vibrational displacement thereof with respect to the housing and the first optical fiber for providing a signal indicative of a measurement of any perturbation of the sensor. Damping or tailoring of the sensor to be responsive to selected levels of perturbation is provided by altering the diameter of optical fibers or by immersing at least a portion of the free span length of the vibration sensing optical fiber into a liquid of a selected viscosity.

Dooley, Joseph B. (Harriman, TN); Muhs, Jeffrey D. (Lenoir City, TN); Tobin, Kenneth W. (Harriman, TN)

1995-01-01

427

Depletion lengths in semiconductor nanostructures  

NASA Astrophysics Data System (ADS)

We calculate the depletion length, W( R), at the surface of a cylindrical nanostructure of radius R and show that W( R) satisfies the inequality Wp? W( R)? Rc, where W p= 2? ?/(e 2N d) is the depletion length at a planar interface ( ? is the surface potential energy barrier, ? is the dielectric constant and Nd is the doping density), and R c= 2W p is, as we show, a critical radius below which, for R? Rc, the structure is fully depleted. The standard result Wp therefore underestimates the depletion length in a finite structure. The discrepancy between W( R) and Wp becomes significant when the dimensions of the structure becomes comparable to the depletion length, as can occur in nanostructure devices.

Luscombe, J. H.; Frenzen, C. L.

2002-06-01

428

The optical design of a visible adaptive optics system for the Magellan Telescope  

NASA Astrophysics Data System (ADS)

The Magellan Adaptive Optics system will achieve first light in November of 2012. This AO system contains several subsystems including the 585-actuator concave adaptive secondary mirror, the Calibration Return Optic (CRO) alignment and calibration system, the CLIO 1-5 microm IR science camera, the movable guider camera and active optics assembly, and the W-Unit, which contains both the Pyramid Wavefront Sensor (PWFS) and the VisAO visible science camera. In this dissertation, we present details of the design, fabrication, assembly, alignment, and laboratory performance of the VisAO camera and its optical components. Many of these components required a custom design, such as the Spectral Differential Imaging Wollaston prisms and filters and the coronagraphic spots. One component, the Atmospheric Dispersion Corrector (ADC), required a unique triplet design that had until now never been fabricated and tested on sky. We present the design, laboratory, and on-sky results for our triplet ADC. We also present details of the CRO test setup and alignment. Because Magellan is a Gregorian telescope, the ASM is a concave ellipsoidal mirror. By simulating a star with a white light point source at the far conjugate, we can create a double-pass test of the whole system without the need for a real on-sky star. This allows us to test the AO system closed loop in the Arcetri test tower at its nominal design focal length and optical conjugates. The CRO test will also allow us to calibrate and verify the system off-sky at the Magellan telescope during commissioning and periodically thereafter. We present a design for a possible future upgrade path for a new visible Integral Field Spectrograph. By integrating a fiber array bundle at the VisAO focal plane, we can send light to a pre-existing facility spectrograph, such as LDSS3, which will allow 20 mas spatial sampling and R˜1,800 spectra over the band 0.6-1.05 microm. This would be the highest spatial resolution IFU to date, either from the ground or in space.

Kopon, Derek

429

Grazing incidence neutron optics  

NASA Technical Reports Server (NTRS)

Neutron optics based on the two-reflection geometries are capable of controlling beams of long wavelength neutrons with low angular divergence. The preferred mirror fabrication technique is a replication process with electroform nickel replication process being preferable. In the preliminary demonstration test an electroform nickel optics gave the neutron current density gain at the focal spot of the mirror at least 8 for neutron wavelengths in the range from 6 to 20 .ANG.. The replication techniques can be also be used to fabricate neutron beam controlling guides.

Gubarev, Mikhail V. (Inventor); Ramsey, Brian D. (Inventor); Engelhaupt, Darell E. (Inventor)

2012-01-01

430

Focal mechanisms produced by shear faulting in weakly transversely isotropic crustal rocks  

E-print Network

Focal mechanisms produced by shear faulting in weakly transversely isotropic crustal rocks Václav%. Such values are significant and detectable in carefully determined focal mechanisms. INTRODUCTION Focal, pore pressure, and tectonic stress in a seismically active area. In exploration geophys- ics, focal

Cerveny, Vlastislav

431

When Is Input Salient? An Exploratory Study of Sentence Location and Word Length Effects on Input Processing  

ERIC Educational Resources Information Center

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…

Carroll, Susanne E.

2012-01-01

432

The Focal Surface of the JEM-EUSO Instrument  

SciTech Connect

The Extreme Universe Space Observatory on JEM/EF (JEM-EUSO) is a space mission to study extremely high-energy cosmic rays. The JEM-EUSO instrument is a wide-angle refractive telescope in the near-ultraviolet wavelength region which will be mounted to the International Space Station. Its goal is to measure time-resolved fluorescence images of extensive air showers in the atmosphere. In this paper we describe in detail the main features and technological aspects of the focal surface of the instrument. The JEM-EUSO focal surface is a spherically curved surface, with an area of about 4.5m{sup 2}. The focal surface detector is made of more than 5,000 multi-anode photomultipliers (MAPMTs). Current baseline is Hamamatsu R11265-03-M64. The approach to the focal surface detector is highly modular. Photo-Detector-Modules (PDM) are the basic units that drive the mechanical structure and data acquisition. Each PDM consists of 9 Elementary Cells (ECs). The EC, which is the basic unit of the MAPMT support structure and of the front-end electronics, contains 4 units of MAPMTs. In total, about 1,200 ECs or about 150 PDMs are arranged on the whole of the focal surface of JEM-EUSO.

Kawasaki, Y. [Computational Astrophysics Lab., ASI, RIKEN (Japan); EUSO Team, ASI, RIKEN (Japan); Casolino, M. [INFN and Physics Department of Univresity of Rome 'Tor Vergata' (Italy); EUSO Team, ASI, RIKEN (Japan); Gorodetzky, P. [APC-AstroParticule et Cosmologie (France); Santangelo, A. [Universitity of Tuebingen (Germany); Ricci, M. [INFN, Laboratori Nazionali di Frascati (Italy); Kajino, F. [Department of Physics, Konan University (Japan); Ebisuzaki, T. [Computational Astrophysics Lab., ASI, RIKEN (Japan)

2011-09-22

433

Hepatic focal nodular hyperplasia: angiography, CT, sonography, and scintigraphy  

SciTech Connect

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.

Rogers, J.V. (Univ. of Washington, Seattle); Mack, L.A.; Freeny, P.C.; Johnson, M.L.; Sones, P.J.

1981-11-01

434

Hot spot liver scan in focal nodular hyperplasia  

SciTech Connect

In scintigraphy of the liver with radiocolloid, space-occupying lesions generally are visualized as regions of decreased accumulation of radioactivity. Rarely focal areas of increased activity are depicted; most are related to altered vascular dynamics in the liver secondary to obstruction of the superior or inferior vena cava or the hepatic veins. There are reports of single cases of focally increased activity due to a hepatic hemangioma, hepatic venoocclusive disease, herniation of a part of the liver, and a liver hot spot found after radiocolloid injection via a malpositioned central venous catheter in one of the hepatic vein branches. In patients with focal nodular hyperplasia, liver scans with solitary defects as well as normal patterns are found. In some cases, increased uptake of colloid in the lesion has been documented. Pasquier and Dorta reported a patient with a palpable mass in the left liver lobe with increased accumulation of radioactivity on the radiocolloid liver scan. The histologic diagnosis was hamartoma, but reviewing the description and considering the confusion in the past concerning the nomenclature, this case is suggestive of focal nodular hyperplasia. We report a patient with focal nodular hyperplasia who had increased radiocolloid uptake in the lesion. The radionuclide studies are compared with angiography, sonography, and computed tomography. An explanation for the localized increased colloid accumulation based on histologic findings is suggested.

Piers, D.A. (Univ. Hospital, Groningen, Netherlands); Houthoff, H.J.; Krom, R.A.F.; Schuur, K.H.; Sikkens, H.; Weits, J.

1980-12-01

435

MutComFocal: an integrative approach to identifying recurrent and focal genomic alterations in tumor samples  

PubMed Central

Background Most tumors are the result of accumulated genomic alterations in somatic cells. The emerging spectrum of alterations in tumors is complex and the identification of relevant genes and pathways remains a challenge. Furthermore, key cancer genes are usually found amplified or deleted in chromosomal regions containing many other genes. Point mutations, on the other hand, provide exquisite information about amino acid changes that could be implicated in the oncogenic process. Current large-scale genomic projects provide high throughput genomic data in a large number of well-characterized tumor samples. Methods We define a Bayesian approach designed to identify candidate cancer genes by integrating copy number and point mutation information. Our method exploits the concept that small and recurrent alterations in tumors are more informative in the search for cancer genes. Thus, the algorithm (Mutations with Common Focal Alterations, or MutComFocal) seeks focal copy number alterations and recurrent point mutations within high throughput data from large panels of tumor samples. Results We apply MutComFocal to Diffuse Large B-cell Lymphoma (DLBCL) data from four different high throughput studies, totaling 78 samples assessed for copy number alterations by single nucleotide polymorphism (SNP) array analysis and 65 samples assayed for protein changing point mutations by whole exome/whole transcriptome sequencing. In addition to recapitulating known alterations, MutComFocal identifies ARID1B, ROBO2 and MRS1 as candidate tumor suppressors and KLHL6, IL31 and LRP1 as putative oncogenes in DLBCL. Conclusions We present a Bayesian approach for the identification of candidate cancer genes by integrating data collected in large number of cancer patients, across different studies. When trained on a well-studied dataset, MutComFocal is able to identify most of the reported characterized alterations. The application of MutComFocal to large-scale cancer data provides the opportunity to pinpoint the key functional genomic alterations in tumors. PMID:23531283

2013-01-01

436

Advanced simulation methods to detect resonant frequency stack up in focal plane design  

NASA Astrophysics Data System (ADS)

Wire used to connect focal plane electrical connections to external electrical circuitry can be modeled using the length, diameter and loop height to determine the resonant frequency. The design of the adjacent electric board and mounting platform can also be analyzed. The combined resonant frequency analysis can then be used to decouple the different component resonant frequencies to eliminate the potential for metal fatigue in the wires. It is important to note that the nominal maximum stress values that cause metal fatigue can be much less than the ultimate tensile stress limit or the yield stress limit and are degraded further at resonant frequencies. It is critical that tests be done to qualify designs that are not easily simulated due to material property variation and complex structures. Sine wave vibration testing is a critical component of qualification vibration and provides the highest accuracy in determining the resonant frequencies which can be reduced or uncorrelated improving the structural performance of the focal plane assembly by small changes in design damping or modern space material selection. Vibration flow down from higher levels of assembly needs consideration for intermediary hardware, which may amplify or attenuate the full up system vibration profile. A simple pass through of vibration requirements may result in over test or missing amplified resonant frequencies that can cause system failure. Examples are shown of metal wire fatigue such as discoloration and microscopic cracks which are visible at the submicron level by the use of a scanning electron microscope. While it is important to model and test resonant frequencies the Focal plane must also be constrained such that Coefficient of Thermal expansion mismatches are allowed to move and not overstress the FPA.

Adams, Craig; Malone, Neil R.; Torres, Raymond; Fajardo, Armando; Vampola, John; Drechsler, William; Parlato, Russell; Cobb, Christopher; Randolph, Max; Chiourn, Surath; Swinehart, Robert

2014-09-01

437

Imaging techniques for prostate cancer: implications for focal therapy  

PubMed Central

The multifocal nature of prostate cancer has necessitated whole-gland therapy in the past; however, since the widespread use of PSA screening, patients frequently present with less-advanced disease. Many men with localized disease wish to avoid the adverse effects of whole-gland therapy; therefore, focal therapy for prostate cancer is being considered as a treatment option. For focal treatment to be viable, accurate imaging is required for diagnosis, staging, and monitoring of treatment. Developments in MRI and PET have brought more attention to prostate imaging and the possibility of improving the accuracy of focal therapy. In this Review, we discuss the advantages and disadvantages of conventional methods for imaging the prostate, new developments for targeted imaging, and the possible role of image-guided biopsy and therapy for localized prostate cancer. PMID:19352394

Turkbey, Baris; Pinto, Peter A.; Choyke, Peter L.

2012-01-01

438

Role of scintigraphy in focally abnormal sonograms of fatty livers  

SciTech Connect

Fatty infiltration of the liver may cause a range of focal abnormalities on hepatic sonography which may simulate hepatic nodular lesions. Discrete deposits of fat or islands of normal tissue which are uninvolved by fatty infiltration may stand out as potential space-occupying lesions on the sonograms. Twelve patients with such focally abnormal ultrasound images were referred for liver scintigraphy with /sup 133/Xe and /sup 99m/Tc colloidal SPECT studies to clarify the issue. These examinations helped identify, in nine of 12 patients, the innocent nature of the sonographic abnormalities which were simply related to the fat deposition process. Further, (/sup 99m/Tc)RBC scans defined the additional pathologic process in three patients in whom actual space-occupying lesions were indeed present in the liver. Scintigraphy has an important role to play in the understanding of focal hepatic ultrasound abnormalities particularly in unsuspected hepatic steatosis.

Lisbona, R.; Mishkin, S.; Derbekyan, V.; Novales-Diaz, J.A.; Roy, A.; Sanders, L.

1988-06-01

439

CLAES focal plane array. [Cryogenic Limb Array Etalon Spectrometer  

NASA Technical Reports Server (NTRS)

The Cryogenic Limb Array Etalon Spectrometer for the NASA Upper Atmospheric Research Satellite uses solid-state focal plane arrays to detect emission from the earth's atmosphere over the IR wavelength range 3.5 to 13 microns. This paper discusses the design of the focal plane detector assembly and compares calculated performance with measurements. Measurements were made of focal plane noise and responsivity as functions of frequency (2 to 500 Hz) and temperature (12 to 19 K), pixel-to-pixel and across-array crosstalk, and linearity over a dynamic range of 100,000. The measurements demonstrate that the arrays satisfy the science requirements, and that, in general, there is reasonable agreement between the measurements and the analytical model.

Roche, A. E.; Sterritt, L. W.; Kumer, J. B.; Callary, P. C.; Nielsen, R. L.

1989-01-01

440

Focal adhesion kinase signaling promotes phagocytosis of integrin-bound photoreceptors  

PubMed Central

Daily ?v?5 integrin-dependent phagocytosis of spent photoreceptor outer segment fragments by the retinal pigment epithelium (RPE) is critical for retinal function. This study identifies a key role for focal adhesion kinase (FAK) in RPE phagocytosis. Particle binding increases FAK complex formation with ?v?5 receptors at the apical, phagocytic RPE surface and activates FAK. Subsequent particle engulfment coincides with dissociation of activated FAK from ?v?5. Mutant FAK retaining focal adhesion targeting but lacking kinase activity interferes with recruitment of full-length FAK to ?v?5 and abrogates FAK activation in response to RPE phagocytic challenge. Such inhibition of FAK signaling has no effect on ?v?5-dependent binding of particles but blocks their engulfment. Conversely, FAK re-expression promotes particle engulfment by FAK null fibroblasts. Selective ligation of ?v?5 receptors at the apical RPE surface is sufficient to phosphorylate and mobilize FAK. Furthermore, FAK phagocytic signaling is independent of the internalization receptor MerTK. In contrast, inhibition of FAK signaling diminishes MerTK phosphorylation. These results demonstrate that FAK provides an essential link between binding and engulfment mechanisms of integrin-mediated phagocytosis. PMID:12912913

Finnemann, Silvia C.

2003-01-01

441

Ultrashort optical pulse characterization using WS? monolayers.  

PubMed

We demonstrate the application of two-dimensional materials for ultrashort optical pulse characterization. Monolayer transition metal dichalcogenides, such as tungsten disulfide (WS?), possess extraordinarily large second-order nonlinear susceptibility, and due to their atomic thickness, have relaxed phase-matching requirements and, hence, an inherently wide bandwidth. Synthesized monolayer WS? triangular islands were used to characterize ultrashort optical pulses at the focal point of an objective lens through second-harmonic generation collinear frequency-resolved optical gating. PMID:24562152

Janisch, Corey; Mehta, Nikhil; Ma, Ding; Elías, Ana Laura; Perea-López, Néstor; Terrones, Mauricio; Liu, Zhiwen

2014-01-15

442

Optical vortex arrays from smectic liquid crystals.  

PubMed

We demonstrate large-area, closely-packed optical vortex arrays using self-assembled defects in smectic liquid crystals. Self-assembled smectic liquid crystals in a three-dimensional torus structure are called focal conic domains. Each FCD, having a micro-scale feature size, produces an optical vortex with consistent topological charge of 2. The spiral profile in the interferometry confirms the formation of an optical vortex, which is predicted by Jones matrix calculations. PMID:24663788

Son, Baeksik; Kim, Sejeong; Kim, Yun Ho; Käläntär, K; Kim, Hwi-Min; Jeong, Hyeon-Su; Choi, Siyoung Q; Shin, Jonghwa; Jung, Hee-Tae; Lee, Yong-Hee

2014-02-24

443

Optical pumping in a whispering-mode optical waveguide  

DOEpatents

A device and method for optical pumping in a whispering mode optical waveguide are described. Both a helical ribbon and cylinder are disclosed which incorporate an additional curvature for confining the beam to increase intensity. An optical pumping medium is disposed in the optical path of the beam as it propagates along the waveguide. Optical pumping is enhanced by the high intensities of the beam and long interaction path lengths which are achieved in a small volume.

Kurnit, N.A.

1981-08-11

444

Focal therapy in prostate cancer: the current situation  

PubMed Central

Prostate cancer is one of the most significant pathologies in the field of urology. The adoption of screening strategies and improvements in biopsies have resulted in an increase in early-stage tumour detection. Radical global therapies provide very good oncological results in localised prostate cancer. However, excess treatment in low- and, in some cases, intermediate-risk groups affects the quality of life of these patients. In the case of localised prostate cancer, focal therapies offer a minimally invasive option with good results with respect to established treatments. Although this is currently not a standard treatment, it represents the therapeutic approach with the greatest potential. This literature review has the following objectives: to define selection criteria for patients who are candidates for focal therapy, to assess the current situation and results of the different therapeutic options, and to define procedures in cases of recurrence and for follow-ups. We concluded that focal therapy is a viable therapeutic alternative for localised prostate cancer, specifically cryosurgery and high-intensity targeted ultrasound, which have acceptable oncologic results and a lower comorbidity compared with global treatments. Studies with a high level of scientific evidence are still needed to validate these results. Acquisition of evidence A search was carried out on the Medline (PubMed), EMBASE, Web of Science and Cochrane databases of all papers published before 31 July 2013. We included clinical studies and literature reviews that evaluated primary focal therapy for prostate cancer confirmed by biopsy and excluded focal rescue therapy studies. The keywords used were focal therapy and prostate cancer. Initially, we found 42 articles; 15 studies were excluded because they did not meet the minimum criteria for inclusion. A total of 1350 cases were treated throughout 27 studies. PMID:24944577

Jacome-Pita, FX; Sanchez-Salas, R; Barret, E; Amaruch, N; Gonzalez-Enguita, C; Cathelineau, X

2014-01-01

445

Radical prostatectomy specimens - a voice against focal therapy  

PubMed Central

Introduction The main treatment methods of prostate carcinoma are surgery and radiation therapy, both having serious side effects. Because of these side effects, the idea of organ preserving therapy emerged. Rationale to perform focal therapy is to preserve the prostate gland, along with potency and continence, offering good cancer control with appropriate treatment. The idea of gland sparing therapy is quite controver