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1

Adaptive optics in wide-field microscopy  

NASA Astrophysics Data System (ADS)

Three-dimensional live imaging in cell biology is hindered by optical aberrations which degrade the resolution and signal-to-noise ratio as the focal plane is moved deeper into the sample. The solution to this problem is to use adaptive optics to correct the aberrations. In this paper, we discuss our work on applying adaptive optics to wide-field fluorescence microscopy. We demonstrate correction of depth-aberrations and focusing using a deformable mirror in open-loop operation. We then discuss the use of phase retrieval and phase diversity in adaptive optics.

Kner, Peter; Kam, Zvi; Agard, David; Sedat, John

2011-02-01

2

Optical modeling of the wide-field imaging interferometry testbed  

NASA Astrophysics Data System (ADS)

The technique of wide field imaging for optical/IR interferometers for missions like Space Infrared Interferometric (SPIRIT), Submillimeter Probe of the Evolution of Cosmic Structure (SPECS), and the Terrestrial Planet Finder (TPF-I)/DARWIN has been demonstrated through the Wide-field Imaging Interferometry Testbed (WIIT). In this paper, we present an optical model of the WIIT testbed using the commercially available optical modeling and analysis software FRED. Interferometric results for some simple source targets are presented for a model with ideal surfaces and compared with theoretical closed form solutions. Measured surface deformation data of all mirror surfaces in the form of Zernike coefficients are then added to the optical model compared with results of some simple source targets to laboratory test data. We discuss the sources of error and approximations in the current FRED optical model. Future plans to refine the optical model are also be discussed.

Thompson, Anita K.; Martino, Anthony J.; Rinehart, Stephen A.; Leisawitz, David T.; Leviton, Douglas B.; Frey, Bradley J.

2006-06-01

3

Wide field strip-imaging optical system  

NASA Technical Reports Server (NTRS)

A strip imaging wide angle optical system is provided. The optical system is provided with a 'virtual' material stop to avoid aberrational effects inherent in wide angle optical systems. The optical system includes a spherical mirror section for receiving light from a 180-degree strip or arc of a target image. Light received by the spherical mirror section is reflected to a frusto-conical mirror section for subsequent rereflection to a row of optical fibers. Each optical fiber transmits a portion of the received light to a detector. The optical system exploits the narrow cone of acceptance associated with optical fibers to substantially eliminate vignetting effects inherent in wide-angle systems. Further, the optical system exploits the narrow cone of acceptance of the optical fibers to substantially limit spherical aberration. The optical system is ideally suited for any application wherein a 180-degree strip image need be detected, and is particularly well adapted for use in hostile environments such as in planetary exploration.

Vaughan, Arthur H. (inventor)

1994-01-01

4

Optical sectioning by wide-field photobleaching imprinting microscopy  

NASA Astrophysics Data System (ADS)

We present a generic wide-field optical sectioning scheme, photobleaching imprinting microscopy (PIM), for depth-resolved cross-sectional fluorescence imaging. Wide-field PIM works by extracting a nonlinear component that depends on the excitation fluence as a result of photobleaching-induced fluorescence decay. Since no specific fluorescent dyes or illumination modules are required, wide-field PIM is easy to implement on a standard microscope. Moreover, wide-field PIM is superior to deconvolution microscopy in removing background fluorescence, yielding a six-fold improvement in image contrast.

Li, Chiye; Gao, Liang; Liu, Yan; Wang, Lihong V.

2013-10-01

5

Wide-Field Optical Imaging of Interstellar Cirrus Clouds  

Microsoft Academic Search

We have carried out wide-field BVRI CCD imaging of a selection of interstellar ``cirrus'' clouds using the Schmidt telescopes at KPNO and CTIO. In most cases, these images are sensitive enough to detect diffuse optical emission in all of the wavelength bands. The optical images have been compared with IRAS infrared maps to study the properties of the interstellar grains

R. M. Cutri; P. Guhathakurta

1994-01-01

6

'Virtual triple Schmidt' - Wide field two-stage optics  

NASA Technical Reports Server (NTRS)

The design concept of an unobscured-wide-field two-stage optical system based on a virtual triple Schmidt (VTS) configuration is presented. It is pointed out that the single large aperture and field-partitioning capability of two-stage systems can lower material and fabrication costs, making the VTS optics suitable for ground-based and space telescopes. The VTS design combines a Schmidt-camera first stage and a second stage comprising two back-to-back Schmidt systems as a 1:1 relay. Aspheric Schmidt correction is achieved at the relayed pupil location for all three systems. The effects of the separation between the error-producing surface and the aperture stop are discussed; the performance of the wavefront-correction system is analyzed; and extensive diagrams, drawings, and graphs of projected performance data are provided.

Manhart, Paul K.

1989-01-01

7

'Virtual triple Schmidt' - Wide field two-stage optics  

NASA Astrophysics Data System (ADS)

The design concept of an unobscured-wide-field two-stage optical system based on a virtual triple Schmidt (VTS) configuration is presented. It is pointed out that the single large aperture and field-partitioning capability of two-stage systems can lower material and fabrication costs, making the VTS optics suitable for ground-based and space telescopes. The VTS design combines a Schmidt-camera first stage and a second stage comprising two back-to-back Schmidt systems as a 1:1 relay. Aspheric Schmidt correction is achieved at the relayed pupil location for all three systems. The effects of the separation between the error-producing surface and the aperture stop are discussed; the performance of the wavefront-correction system is analyzed; and extensive diagrams, drawings, and graphs of projected performance data are provided.

Manhart, Paul K.

1989-04-01

8

Wide field of view adaptive optical system for lightweight deployable telescope technologies  

Microsoft Academic Search

A NASA research contract (NAS1-00116) was awarded to Ball Aerospace & Technologies Corp. in January 2000 to study wide field-of-view adaptive optical systems. These systems will be required on future high resolution Earth remote sensing systems that employ large, flexible, lightweight, deployed primary mirrors. The deformations from these primary mirrors will introduce aberrations into the optical system, which must be

Brian K. McComas; Michael A. Cermak; Edward J. Friedman

2003-01-01

9

3D defect detection using optical wide-field microscopy  

NASA Astrophysics Data System (ADS)

We report a method to detect signed differences in two similar data sets representing 3-dimensional intensity profiles recorded by optical wide-field microscopes. The signed differences describe missing or unexpected intensity values, defined as defects. In technical applications like wafer and mask inspection, data sets often represent surfaces. The reported method is able to describe the size and position especially in relation to the neighboring surface and is called Three-Dimension-Aberration (TDA)-Technology. To increase the tool performance and to handle different sizes of defects a scaled bottom-up method is implemented and started with high reduced data sets for the search of large defects. Each analysis contains three steps. The first step is a correlation to calculate the displacement vector between the similar data sets. In the second step a new data set is created. The new data set consists of intensity differences. Extreme values in the data set represent the position of defects. By the use of linear and non-linear filters the stability of detection can be improved. If all differences are below a threshold the bottom-up method starts with the next larger scaled data set. In the other case it is assumed that the defect is detected and step three starts with the detection of the convex hull of the defect and the search of the neighboring surface. As a result the defect is described by a parameter set including the relative position. Because of the layered structure of the data set and the bottom-up technique the method is suitable for multi-core processor architectures.

Tympel, Volker; Schaaf, Marko; Srocka, Bernd

2007-06-01

10

Telescope with a wide field of view internal optical scanner  

NASA Technical Reports Server (NTRS)

A telescope with internal scanner utilizing either a single optical wedge scanner or a dual optical wedge scanner and a controller arranged to control a synchronous rotation of the first and/or second optical wedges, the wedges constructed and arranged to scan light redirected by topological surfaces and/or volumetric scatterers. The telescope with internal scanner further incorporates a first converging optical element that receives the redirected light and transmits the redirected light to the scanner, and a second converging optical element within the light path between the first optical element and the scanner arranged to reduce an area of impact on the scanner of the beam collected by the first optical element.

Degnan, III, John James (Inventor); Zheng, Yunhui (Inventor)

2012-01-01

11

Wide field/planetary camera optics study. [for the large space telescope  

NASA Technical Reports Server (NTRS)

Design feasibility of the baseline optical design concept was established for the wide field/planetary camera (WF/PC) and will be used with the space telescope (ST) to obtain high angular resolution astronomical information over a wide field. The design concept employs internal optics to relay the ST image to a CCD detector system. Optical design performance predictions, sensitivity and tolerance analyses, manufacturability of the optical components, and acceptance testing of the two mirror Cassegrain relays are discussed.

1979-01-01

12

Towards wide-field retinal imaging with adaptive optics  

NASA Astrophysics Data System (ADS)

In vivo imaging of the retina on humans by means of adaptive optics can lead to a significant gain in resolution. We demonstrate the realization and use of a system made of a Shack-Hartmann wavefront sensor carefully matched to a 13-actuator bimorph deformable mirror sensor, operating at a closed loop frequency of 70 Hz at ?=835 nm. Even with this simple but optimized system with 12 degrees of freedom, correcting only aberrations of moderate orders, we routinely and systematically obtain retinal images containing spatial information up to half the diffraction limit frequency of a dilated (7 mm) iris at a ?=550 nm wavelength (1.6 ?m diffraction spot size). Signal-to-noise ratio on the images is limited by eye safety constraints, but is sufficient to reach the high-frequency information on single, short-exposure (7 ms) images, which clearly show individual cones and capillary details. Correction is highly depending on proper centering of the eye, achieved with an active target. Focusing through the retina is possible with a reduced depth of focus. Variability of moderate order aberrations among dilated subjects has been observed. Using an image fitting algorithm, individual images are used to build a wider field corrected image of the retina (?3°), possibly useful for diagnosis and microcirculation analysis.

Glanc, M.; Gendron, E.; Lacombe, F.; Lafaille, D.; Le Gargasson, J.-F.; Léna, P.

2004-02-01

13

Wide field astronomical image compensation with multiple laser-guided adaptive optics  

NASA Astrophysics Data System (ADS)

We report closed-loop results obtained from the first adaptive optics system to deploy multiple laser guide beacons. The system is mounted on the 6.5 m MMT telescope in Arizona, and is designed to explore advanced altitude-conjugated techniques for wide-field image compensation. Five beacons are made by Rayleigh scattering of laser beams at 532 nm integrated over a range from 20 to 29 km by dynamic refocus of the telescope optics. The return light is analyzed by a unique Shack-Hartmann sensor that places all five beacons on a single detector, with electronic shuttering to implement the beacon range gate. Wavefront correction is applied with the telescope's unique deformable secondary mirror. The system has now begun operations as a tool for astronomical science, in a mode in which the boundary-layer turbulence, close to the telescope, is compensated. Image quality of 0.2-0.3 arc sec is routinely delivered in the near infrared bands from 1.2-2.5 ?m over a field of view of 2 arc min. Although it does not reach the diffraction limit, this represents a 3 to 4-fold improvement in resolution over the natural seeing, and a field of view an order of magnitude larger than conventional adaptive optics systems deliver. We present performance metrics including images of the core of the globular cluster M3 where correction is almost uniform across the full field. We describe plans underway to develop the technology further on the twin 8.4 m Large Binocular Telescope and the future 25 m Giant Magellan Telescope.

Hart, Michael; Milton, N. Mark; Baranec, Christoph; Stalcup, Thomas; Powell, Keith; Bendek, Eduardo; McCarthy, Don; Kulesa, Craig

2009-08-01

14

Holistic optical-digital hybrid-imaging design: wide-field reflective imaging.  

PubMed

Reflective imaging systems are typically limited to small field angles in order to avoid overly large obscurations or off-axis aberrations. Reflective optics are often preferred in astronomy due to the associated lower weight and cost, as well as the absence of chromatic aberrations. Although these advantages are compelling, off-axis aberrations typically limit the field of view to a few degrees, while many imaging applications require a considerably larger useful field of view. A hybrid optical-digital design could alleviate the issues associated with wide-field reflective optics by exploiting the larger design freedom inherent in such systems. In this paper we demonstrate how a holistic design approach can enable reflective imaging systems with a consistently sharp image across a wide field of view. PMID:23759840

Vettenburg, Tom; Harvey, Andrew R

2013-06-10

15

Wide Field Optical Camera for Search and Investigation of Fast Cosmic Transients  

SciTech Connect

The primary purpose of the fast wide field optical camera (WFOC) is to perform continuous, alert-independent observations of optical transients and variable astrophysical sources simultaneously with space-born wide field X- and {gamma}-ray telescopes. In particular the camera can detect possible optical precursors and early prompt emission from cosmic Gamma-Ray Bursts. The real-time source identification software generates alerts that also could be sent to global alert distribution networks such as the GCN. We estimate that in one year of continuous observation with the WFOC we will observe the following numbers of GRB error boxes simultaneously with space- borne telescopes: 1.6 (WXM/HETE-2), 0.5 (SPI/INTEGRAL), and 4 (BAT/SWIFT)

Pozanenko, A.; Loznikov, V. [IKI RAS, Moscow (Russian Federation); Beskin, G.; Karpov, S. [SAO RAS, Karachai-Cherkessia (Russian Federation); Bondar, S.; Ivanov, E. [Kosmoten Observatory, Karachai-Cherkessia (Russian Federation); Biryukov, A.; Zolotukhin, Y. [SAI MSU, Moscow (Russian Federation); Hurley, K. [UC Berkeley Space Sciences Laboratory (United States); Rumyantsev, V. [CrAO, Crimea (Ukraine)

2004-09-28

16

Adaptive optics scanning laser ophthalmoscope with integrated wide-field retinal imaging and tracking  

PubMed Central

We have developed a new, unified implementation of the adaptive optics scanning laser ophthalmoscope (AOSLO) incorporating a wide-field line-scanning ophthalmoscope (LSO) and a closed-loop optical retinal tracker. AOSLO raster scans are deflected by the integrated tracking mirrors so that direct AOSLO stabilization is automatic during tracking. The wide-field imager and large-spherical-mirror optical interface design, as well as a large-stroke deformable mirror (DM), enable the AOSLO image field to be corrected at any retinal coordinates of interest in a field of >25 deg. AO performance was assessed by imaging individuals with a range of refractive errors. In most subjects, image contrast was measurable at spatial frequencies close to the diffraction limit. Closed-loop optical (hardware) tracking performance was assessed by comparing sequential image series with and without stabilization. Though usually better than 10 ?m rms, or 0.03 deg, tracking does not yet stabilize to single cone precision but significantly improves average image quality and increases the number of frames that can be successfully aligned by software-based post-processing methods. The new optical interface allows the high-resolution imaging field to be placed anywhere within the wide field without requiring the subject to re-fixate, enabling easier retinal navigation and faster, more efficient AOSLO montage capture and stitching.

Ferguson, R. Daniel; Zhong, Zhangyi; Hammer, Daniel X.; Mujat, Mircea; Patel, Ankit H.; Deng, Cong; Zou, Weiyao; Burns, Stephen A.

2010-01-01

17

Wide field astronomical image compensation with multiple laser-guided adaptive optics  

Microsoft Academic Search

We report closed-loop results obtained from the first adaptive optics system to deploy multiple laser guide beacons. The system is mounted on the 6.5 m MMT telescope in Arizona, and is designed to explore advanced altitude-conjugated techniques for wide-field image compensation. Five beacons are made by Rayleigh scattering of laser beams at 532 nm integrated over a range from 20

Michael Hart; N. Mark Milton; Christoph Baranec; Thomas Stalcup; Keith Powell; Eduardo Bendek; Don McCarthy; Craig Kulesa

2009-01-01

18

A wide-field time-domain fluorescence lifetime imaging microscope with optical sectioning  

NASA Astrophysics Data System (ADS)

This article describes a wide-field time-domain fluorescence lifetime imaging (FLIM) microscope with optical sectioning. The FLIM system utilizes a wide-field time-gated optical image intensifier, with a minimum gate width of 85 ps, to achieve high temporal resolution of fluorescence decays induced by ultrashort laser pulses. Different configurations, using excitation pulses of picojoule energy at 80 MHz repetition rate and of nanojoule energy at 10 kHz, are compared. The instrument has a temporal dynamic range spanning from 100 ps to tens of ?s and is shown to have a temporal discrimination better than 10 ps. When applied to laser dye samples, it has produced FLIM maps demonstrating sensitivity to variations in both chemical species and local environment, e.g., viscosity. Wide-field optical sectioning is achieved using the technique of structured illumination, which is applied to remove out-of-focus light that can result in lifetime artifacts. The sectioning strength, which may be adjusted by choosing an appropriate spatial modulation frequency, is characterized and shown to be comparable to that of a confocal microscope. Practical considerations concerned with improving the quality of sectioned fluorescence lifetime maps, including using a large bit depth camera, are discussed.

Webb, S. E. D.; Gu, Y.; Lévêque-Fort, S.; Siegel, J.; Cole, M. J.; Dowling, K.; Jones, R.; French, P. M. W.; Neil, M. A. A.; Juškaitis, R.; Sucharov, L. O. D.; Wilson, T.; Lever, M. J.

2002-04-01

19

Optimization of Grazing Incidence Optics for Wide-Field X-Ray Survey Imaging  

NASA Astrophysics Data System (ADS)

Optimization of wide-field X-ray optics could greatly enhance X-ray surveys. Discussions of optimizing wide-field X-ray optics, with field-of-views less-than 1.1 degree-squared, have been made previously in the literature. However, very little has been published about the optimizing of wide-field X-ray optics with larger fields-of-view. We have been working on the design of a wide-field (3.1 degree-squared field-of-view), short focal length (190.5 cm), grazing incidence mirror shell set, with a desired rms image spot size of 15 arcsec. The baseline design incorporates Wolter I type mirror shells with polynomial perturbations applied to the grazing incidence surface. By optimizing the polynomial, the rms image spot size can be minimized for a large range of grazing angles. The overall minimization technique is to efficiently optimize the polynomial coefficients that directly influence the angular resolution, without stepping through the entire multidimensional coefficient space. The multidimensional minimization techniques that have been investigated include: the downhill simplex method; the coupling of genetic algorithms with full and fractional, including Plackett-Burman, factorial designs; and the coupling of genetic algorithms with Box-Behnken and central composite response surface designs. We have also examined the use of neural networks, coupled with genetic algorithms, as a method of multidimensional minimization. Investigations of backpropagation, probabilistic (PNN), general regression (GRNN), and group method of data handling (GMDH) neural networks have been made. We report our findings to date. This research is funded by NASA grant #NAG5-5093.

Roming, P. W. A.; Burrows, D. N.; Garmire, G. P.; Roush, W. B.

1999-12-01

20

Final Optical Design of PANIC, a Wide-Field Infrared Camera for CAHA  

NASA Astrophysics Data System (ADS)

We present the Final Optical Design of PANIC (PAnoramic Near Infrared camera for Calar Alto), a wide-field infrared imager for the Ritchey-Chrtien focus of the Calar Alto 2.2 m telescope. This will be the first instrument built under the German-Spanish consortium that manages the Calar Alto observatory. The camera optical design is a folded single optical train that images the sky onto the focal plane with a plate scale of 0.45 arcsec per 18 ?m pixel. The optical design produces a well defined internal pupil available to reducing the thermal background by a cryogenic pupil stop. A mosaic of four detectors Hawaii 2RG of 2 k ×2 k, made by Teledyne, will give a field of view of 31.9 arcmin ×31.9 arcmin.

Cárdenas, M. C.; Rodríguez Gómez, J.; Lenzen, R.; Sánchez-Blanco, E.

21

Assembly, alignment, and testing of the DECam wide field corrector optics  

NASA Astrophysics Data System (ADS)

The DES project is a 5 year imaging survey of the southern sky using the 4m Blanco Telescope at the Cerro Tololo International Observatory in Chile. A new wide field camera with a 2.2 degree diameter field of view has been built to undertake this survey. The alignment of the large lenses for this camera poses a significant challenge as they have to be aligned to a tolerance of ±50 micrometers. This paper presents the assembly and alignment process of the full optical system along with the test results. Also included is the predicted imaging performance from the as-built system.

Doel, Peter; Brooks, David; Antonik, Michelle L.; Flaugher, Brenna L.; Stefanik, Andrew; Kent, Stephen M.; Gutierrez, Gaston; Cease, Herman P.; Abbott, Timothy M.; Walker, Alistair R.; DePoy, Darren L.; Bernstein, Rebecca A.; Worswick, Sue

2012-09-01

22

Scanner-Free and Wide-Field Endoscopic Imaging by Using a Single Multimode Optical Fiber  

NASA Astrophysics Data System (ADS)

A single multimode fiber is considered an ideal optical element for endoscopic imaging due to the possibility of direct image transmission via multiple spatial modes. However, the wave distortion induced by the mode dispersion has been a fundamental limitation. In this Letter, we propose a method for eliminating the effect of mode dispersion and therefore realize wide-field endoscopic imaging by using only a single multimode fiber with no scanner attached to the fiber. Our method will potentially revolutionize endoscopy in various fields encompassing medicine and industry.

Choi, Youngwoon; Yoon, Changhyeong; Kim, Moonseok; Yang, Taeseok Daniel; Fang-Yen, Christopher; Dasari, Ramachandra R.; Lee, Kyoung Jin; Choi, Wonshik

2012-11-01

23

Scanner-free and wide-field endoscopic imaging by using a single multimode optical fiber  

PubMed Central

A single multimode fiber has been considered an ideal optical element for endoscopic imaging due to the possibility of the direct image transmission via multiple spatial modes. However, the wave distortion induced by the mode dispersion has been a fundamental limitation. In this Letter, we proposed a method for eliminating the effect of the mode dispersion and therefore realized wide-field endoscopic imaging by using only a single multimode fiber with no scanner attached to the fiber. Our method will potentially revolutionize endoscopy in various fields encompassing medicine and industry.

Choi, Youngwoon; Yoon, Changhyeong; Kim, Moonseok; Yang, Taeseok Daniel; Fang-Yen, Christopher; Dasari, Ramachandra R.; Lee, Kyoung Jin; Choi, Wonshik

2013-01-01

24

A Canadian wide-field optical spectrograph for a 30-m telescope  

NASA Astrophysics Data System (ADS)

A wide-field low-resolution multi-object optical spectrograph suitable for a 30-m F/15 telescope is described. The effort to build a 30-m class telescope is gaining momentum. Many science cases for such a telescope make the need for a wide-field seeing-limited spectrograph a high priority. Our concept comprises four identical instruments placed symmetrically around the optical axis of the telescope, this allows smaller dimensions for the spectrographs and their components. Each instrument is placed in one quadrant of the telescope focal plane; a space at the center of the field is free for other instrumentation. Using a dichroic beam-splitter each instrument feeds a "red" and "blue" camera. The total field is 81 square arcmin, the wavelength range covers simultaneously 310 nm to 1000 nm and the spectral resolution (R) is 300 to 5000. The instruments are designed for vertical mounting at a Nasmyth focus to avoid gravity vector changes and reducing mechanical flexure problems during observation. The layout also allows access to internal components for maintenance. The design offers advantages for the location of a slit mask and filters. The instruments can also be used for imaging. Optical and opto-mechanical models and analyses are presented with specifications and expected performance.

Oke, Bev; Laurin, Denis; Powell, Ian; Crampton, David; Pazder, John; Szeto, Kei; Baril, Marc; Saddlemyer, Leslie; Stilburn, James; Roberts, Scott

2004-09-01

25

Optimal grazing incidence optics and its application to wide-field X-ray imaging  

NASA Technical Reports Server (NTRS)

A class of high-resolution, efficient, and wide-field grazing incidence optics is discussed. Optical designs for searching efficiently for distant X-ray clusters are developed. It is shown that a rather general procedure exists for the design of an optical mission if well-defined scientific goals can be provided. Clusters of galaxies with an angular diameter of about 5 arcsec over a field of about 1 deg are resolved so that a comprehensive deep search is possible with a payload of 1/10 the linear dimensions of AXAF. By dropping the requirement for perfect on-axis imagery, searching within a suitably general class of telescope design, and optimizing a quantity directly related to the scientific requirement, it is shown that satisfactory designs do exist. The resulting telescope is shown to be no more difficult to fabricate than existing mirrors, and it can be nested.

Burrows, Christopher J.; Burg, Richard; Giacconi, Riccardo

1992-01-01

26

Catadioptric null test of ultra-deep concave aspheric lens in wide-field optical system.  

PubMed

To test the ultra-deep conic surface in wide-field optical systems, a catadioptric null test method is researched in this paper. Equations of infinite conjugate null test system are established and solved using optical path length. The numeric results of a self-aligning mirror's shapes are fitted by coefficients and validation is done in optical design software. The rms wavefront error is 0.0019? (?=632.8 nm) in the example fitted by five coefficients. Furthermore, by adjusting spherical aberration distributions, an all-spherical finite conjugate null test system is designed, whose rms wavefront error is 0.0309?. The test methods in this paper have been proven to be adaptive to many other similar ultra-deep surfaces, even with higher orders. PMID:23842273

Zhong, Xing; Jin, Guang

2013-07-01

27

Optical design of long focal length and wide field on an aerial CCD camera  

NASA Astrophysics Data System (ADS)

Reconnaissance range and image resolution are increasingly paid more attention to with the development of airborne reconnaissance, the optical system should be in characteristics of long focal length and wide field. At the same flight altitude, the wider field can enlarge ground covering width and increase the reconnaissance range Longer focal length can improve ground sample distance (GSD). Merits and advantages of reflecting system, catadioptric system and refractive system were represented, with the help of code V software, a refractive system was designed to meet the requirements, Optical material with special dispersion was adopted to remove second order spectrum. It has a focal length of 903mm, with the field angle of 4.5°×4.5°, the size of CCD pixels is 10um×10um, spectral scope is from 0.43um to 0.74um, modulation transfer function(MTF) is all above 0.5 in whole field when spatial frequency is at 50lp/mm, distortion is less than 1%, image quality reaches the diffraction limit. The system with long focal length and wide field can satisfy the demand of the wide ground overlay area and high resolution, and can apply in high altitude photograph.

Cheng, Xiaowei; Che, Ying; Xue, Changxi

2009-05-01

28

Fiber optic bundle array wide field-of-view optical receiver for free space optical communications.  

PubMed

We propose a design for a free space optical communications (FSOC) receiver terminal that offers an improved field of view (FOV) in comparison to conventional FSOC receivers. The design utilizes a microlens to couple the incident optical signal into an individual fiber in a bundle routed to remote optical detectors. Each fiber in the bundle collects power from a solid angle of space; utilizing multiple fibers enhances the total FOV of the receiver over typical single-fiber designs. The microlens-to-fiber-bundle design is scalable and modular and can be replicated in an array to increase aperture size. The microlens is moved laterally with a piezoelectric transducer to optimize power coupling into a given fiber core in the bundle as the source appears to move due to relative motion between the transmitter and receiver. The optimum position of the lens array is determined via a feedback loop whose input is derived from a position sensing detector behind another lens. Light coupled into like fibers in each array cell is optically combined (in fiber) before illuminating discrete detectors. PMID:21042349

Hahn, Daniel V; Brown, David M; Rolander, Nathan W; Sluz, Joseph E; Venkat, Radha

2010-11-01

29

Wide-field two-dimensional multifocal optical-resolution photoacoustic computed microscopy  

PubMed Central

Optical-resolution photoacoustic microscopy (OR-PAM) is an emerging technique that directly images optical absorption in tissue at high spatial resolution. To date, the majority of OR-PAM systems are based on single focused optical excitation and ultrasonic detection, limiting the wide-field imaging speed. While one-dimensional multifocal OR-PAM (1D-MFOR-PAM) has been developed, the potential of microlens and transducer arrays has not been fully realized. Here, we present the development of two-dimensional multifocal optical-resolution photoacoustic computed microscopy (2D-MFOR-PACM), using a 2D microlens array and a full-ring ultrasonic transducer array. The 10 × 10 mm2 microlens array generates 1800 optical foci within the focal plane of the 512-element transducer array, and raster scanning the microlens array yields optical-resolution photoacoustic images. The system has improved the in-plane resolution of a full-ring transducer array from ?100 µm to 29 µm and achieved an imaging time of 36 seconds over a 10 × 10 mm2 field of view. In comparison, the 1D-MFOR-PAM would take more than 4 minutes to image over the same field of view. The imaging capability of the system was demonstrated on phantoms and animals both ex vivo and in vivo.

Xia, Jun; Li, Guo; Wang, Lidai; Nasiriavanaki, Mohammadreza; Maslov, Konstantin; Engelbach, John A.; Garbow, Joel R.; Wang, Lihong V.

2014-01-01

30

Computational Optical Imaging Systems for Spectroscopy and Wide Field-of-View Gigapixel Photography  

NASA Astrophysics Data System (ADS)

This dissertation explores computational optical imaging methods to circumvent the physical limitations of classical sensing. An ideal imaging system would maximize resolution in time, spectral bandwidth, three-dimensional object space, and polarization. Practically, increasing any one parameter will correspondingly decrease the others. Spectrometers strive to measure the power spectral density of the object scene. Traditional pushbroom spectral imagers acquire high resolution spectral and spatial resolution at the expense of acquisition time. Multiplexed spectral imagers acquire spectral and spatial information at each instant of time. Using a coded aperture and dispersive element, the coded aperture snapshot spectral imagers (CASSI) here described leverage correlations between voxels in the spatial-spectral data cube to compressively sample the power spectral density with minimal loss in spatial-spectral resolution while maintaining high temporal resolution. Photography is limited by similar physical constraints. Low f/# systems are required for high spatial resolution to circumvent diffraction limits and allow for more photon transfer to the film plain, but require larger optical volumes and more optical elements. Wide field systems similarly suffer from increasing complexity and optical volume. Incorporating a multi-scale optical system, the f/#, resolving power, optical volume and wide field of view become much less coupled. This system uses a single objective lens that images onto a curved spherical focal plane which is relayed by small micro-optics to discrete focal planes. Using this design methodology allows for gigapixel designs at low f/# that are only a few pounds and smaller than a one-foot hemisphere. Computational imaging systems add the necessary step of forward modeling and calibration. Since the mapping from object space to image space is no longer directly readable, post-processing is required to display the required data. The CASSI system uses an undersampled measurement matrix that requires inversion while the multi-scale camera requires image stitching and compositing methods for billions of pixels in the image. Calibration methods and a testbed are demonstrated that were developed specifically for these computational imaging systems.

Kittle, David Scott

31

Cryogenic solid Schmidt camera as a base for future wide-field IR systems  

NASA Astrophysics Data System (ADS)

Work is focused on study of capability of solid Schmidt camera to serve as a wide-field infrared lens for aircraft system with whole sphere coverage, working in 8-14 um spectral range, coupled with spherical focal array of megapixel class. Designs of 16 mm f/0.2 lens with 60 and 90 degrees sensor diagonal are presented, their image quality is compared with conventional solid design. Achromatic design with significantly improved performance, containing enclosed soft correcting lens behind protective front lens is proposed. One of the main goals of the work is to estimate benefits from curved detector arrays in 8-14 um spectral range wide-field systems. Coupling of photodetector with solid Schmidt camera by means of frustrated total internal reflection is considered, with corresponding tolerance analysis. The whole lens, except front element, is considered to be cryogenic, with solid Schmidt unit to be flown by hydrogen for improvement of bulk transmission.

Yudin, Alexey N.

2011-10-01

32

Hardware Results for the Wide-field Infrared Survey Explorer (WISE) Telescope, Scanner, and Imaging Optics  

NASA Astrophysics Data System (ADS)

In 2008 L-3 Communications SSG-Tinsley completed alignment, testing, and delivery of the scanner, telescope, and aft imaging optical system for the Wide-field Infrared Survey Explorer (WISE). Hardware and test results are presented. WISE is a NASA MIDEX mission within the Explorers Program that will perform an all-sky survey in four infrared bands. L-3 SSG, under contract to the Space Dynamics Laboratory, provided a 40 cm afocal telescope, a scan mirror for back-scan during integration, and aft optics imager assembly. All modules operate below 17 Kelvin. The all-reflective system uses aluminum mirrors and metering structures. The afocal telescope provides distortion control to better than two parts in a thousand to prevent image blur during internal scanning. The one-axis scan mirror at the exit pupil scans the detectors’ field-of-view across the telescope field-of-regard, countering the orbital motion and freezing the line of sight during the multi-second exposure period. The five-mirror imaging optics module follows the scan mirror and feeds dichroic beamsplitters that separate the energy into four channels between 2.8 and 26 microns. Design, manufacturing, and test were completed successfully and the subsystems have been delivered for higher level integration and test.

Schwalm, Mark; Akerstrom, A.; Barry, M.; Guregian, J.; LaMalva, F.; Laquidara, P.; Regan, J.; Ugolini, V.

2009-01-01

33

A small animal time-resolved optical tomography platform using wide-field excitation  

NASA Astrophysics Data System (ADS)

Small animal imaging plays a critical role in present day biomedical research by filling an important gap in the translation of research from the bench to the bedside. Optical techniques constitute an emerging imaging modality which have tremendous potential in preclinical applications. Optical imaging methods are capable of non-invasive assessment of the functional and molecular characteristics of biological tissue. The three-dimensional optical imaging technique, referred to as diffuse optical tomography, provides an approach for the whole-body imaging of small animal models and can provide volumetric maps of tissue functional parameters (e.g. blood volume, oxygen saturation etc.) and/or provide 3D localization and quantification of fluorescence-based molecular markers in vivo. However, the complex mathematical reconstruction problem associated with optical tomography and the cumbersome instrumental designs limits its adoption as a high-throughput quantitative whole-body imaging modality in current biomedical research. The development of new optical imaging paradigms is thus necessary for a wide-acceptance of this new technology. In this thesis, the design, development, characterization and optimization of a small animal optical tomography system is discussed. Specifically, the platform combines a highly sensitive time-resolved imaging paradigm with multi-spectral excitation capability and CCD-based detection to provide a system capable of generating spatially, spectrally and temporally dense measurement datasets. The acquisition of such data sets however can take long and translate to often unrealistic acquisition times when using the classical point source based excitation scheme. The novel approach in the design of this platform is the adoption of a wide-field excitation scheme which employs extended excitation sources and in the process allows an estimated ten-fold reduction in the acquisition time. The work described herein details the design of the imaging platform employing DLP-based excitation and time-gated intensified CCD detection and the optimal system operation parameters are determined. The feasibility this imaging approach and accuracy of the system in reconstructing functional parameters and fluorescence markers based on lifetime contrast is established through phantom studies. As a part of the system characterization, the effect of noise in time-resolved optical tomography is investigated and propagation of system noise in optical reconstructions is established. Furthermore, data processing and measurement calibration techniques aimed at reducing the effect of noise in reconstructions are defined. The optimization of excitation pattern selection is established through a novel measurement-guided iterative pattern correction scheme. This technique referred to as Adaptive Full-Field Optical Tomography was shown to improve reconstruction performances in murine models by reducing the dynamic range in photon flux measurements on the surface. Lastly, the application of the unique attributes of this platform to a biologically relevant imaging application, referred to as Forster Resonance Energy Transfer is described. The tomographic imaging of FRET interaction in vivo on a whole-body scale is achieved using the wide-field imaging approach based on lifetime contrast. This technique represents the first demonstration of tomographic FRET imaging in small animals and has significant potential in the development of optical imaging techniques in varied applications ranging from drug discovery to in vivo study of protein-protein interaction.

Venugopal, Vivek

34

Preliminary optical design of PANIC, a wide-field infrared camera for CAHA  

NASA Astrophysics Data System (ADS)

In this paper, we present the preliminary optical design of PANIC (PAnoramic Near Infrared camera for Calar Alto), a wide-field infrared imager for the Calar Alto 2.2 m telescope. The camera optical design is a folded single optical train that images the sky onto the focal plane with a plate scale of 0.45 arcsec per 18 ?m pixel. A mosaic of four Hawaii 2RG of 2k x 2k made by Teledyne is used as detector and will give a field of view of 31.9 arcmin x 31.9 arcmin. This cryogenic instrument has been optimized for the Y, J, H and K bands. Special care has been taken in the selection of the standard IR materials used for the optics in order to maximize the instrument throughput and to include the z band. The main challenges of this design are: to produce a well defined internal pupil which allows reducing the thermal background by a cryogenic pupil stop; the correction of off-axis aberrations due to the large field available; the correction of chromatic aberration because of the wide spectral coverage; and the capability of introduction of narrow band filters (~1%) in the system minimizing the degradation in the filter passband without a collimated stage in the camera. We show the optomechanical error budget and compensation strategy that allows our as built design to met the performances from an optical point of view. Finally, we demonstrate the flexibility of the design showing the performances of PANIC at the CAHA 3.5m telescope.

Cárdenas, M. C.; Rodríguez Gómez, J.; Lenzen, R.; Sánchez-Blanco, E.

2008-08-01

35

Research on improving resolution changed from optical images for bore detecting into video signal wide field-of-view  

NASA Astrophysics Data System (ADS)

With the discussion in the relationship between field of view and resolution in photoelectronic inspection technology, methods and measures are stressed in the paper to output optical images for bore detecting in video frequency with CCD technology in the case of wide field of view and high resolution with the application of nodal point and photoelectronic technology in a optical system, which can solve the engineering problems of wide field of view and high resolution optical image transmission in video frequency with CCD technology in the field of industrial high precision bore inspection.

Li, Ji X.; Gao, Bo

1994-08-01

36

Optimizing X-Ray Optical Prescriptions for Wide-Field Applications  

NASA Technical Reports Server (NTRS)

X-ray telescopes with spatial resolution optimized over the field of view (FOV) are of special interest for missions, such as WFXT, focused on moderately deep and deep surveys of the x-ray sky, and for solar x-ray observations. Here we report on the present status of an on-going study of the properties of Wolter I and polynominal grazing incidence designs with a view to gain a deeper insight into their properties and simply the design process. With these goals in mind, we present some results in the complementary topics of (1) properties of Wolter I x-ray optics and polynominal x-ray optic ray tracing. Of crucial importance for the design of wide-field x-ray optics is the optimization criteria. Here we have adopted the minimization of a merit function, M, which measures the spatial resolution averaged over the FOV: M= ((integral of d phi) between the limits of 0 and 2 pi) (integral of d theta theta w(theta) sigma square (theta,phi) between the limits of 0 and theta(sub FOV)) (integral of d phi between the limits of 0 and phi/4) (Integral of d theta theta w(theta) between the limits of 0 and theta(sub FOV) where w(theta(sub 1) is a weighting function and Merit function: sigma-square (theta, phi) = summation of (x,y,z) [-<(x,y,z)> (exp 2)] is the spatial variance for a point source on the sky at polar and azimuthal off-axis angles (theta,phi).

Elsner, R. F.; O'Dell, S. L.; Ramsey, B. D.; Weisskopf, M. C.

2010-01-01

37

Research on improving resolution changed from optical images for bore detecting into video signal wide field-of-view  

Microsoft Academic Search

With the discussion in the relationship between field of view and resolution in photoelectronic inspection technology, methods and measures are stressed in the paper to output optical images for bore detecting in video frequency with CCD technology in the case of wide field of view and high resolution with the application of nodal point and photoelectronic technology in a optical

Ji X. Li; Bo Gao

1994-01-01

38

Optical designs with wide field-of-view adaptive optics for IMAKA of CFHT  

NASA Astrophysics Data System (ADS)

As a ground-layer adaptive optics (GLAO) system can correct the wavefront errors caused by turbulence close to the Canada-France-Hawaii telescope (CFHT), an intensive study is in progress to determine the feasibility and the pertinence of equipping the CFHT of such a GLAO system. More specifically, the study concerns the implementation of GLAO capabilities using a deformable mirror inserted into the optical path of an optical relay. The studied system called IMAKA would be used both for the dynamic correction of the wavefront errors caused by air turbulence and the increases of the telescope effective field of view. The objective pursued by IMAKA is to achieve a PSF with Full Width at Half Maximum of less than 0.15" over a 1-degree field of view for extended wavebands within the spectral waveband of 470 nm - 900 nm. This paper presents the main results of a study conducted by INO about the optical design challenges of the IMAKA system. INO has proposed 4 different approaches for the realization of the system and made preliminary optical designs for each of them. The science camera and deformable mirror in the proposed designs are located below the Cassegrain environment for three of the proposed configurations and between the primary mirror and the top ring for the fourth design. In all the proposed configurations, the effective focal length of the telescope with the added correction relay is about 20.63 m for a working focal ratio of about 5.74. The design configurations included in this paper have achieved nearly diffraction limited performances with a deformable mirror having a diameter inferior to 0.5 m and flat or mild curvature nominal shape. Based on our preliminary optical design and performance analysis with the 4 optical design approaches, it seems possible to achieve most of the IMAKA requirements.

Wang, Min; Doucet, Michel; Gauvin, Jonny; Châteauneuf, François; Salmon, Derrick

2010-07-01

39

Optical Design Trade Study for the Wide Field Infrared Survey Telescope WFIRST.  

National Technical Information Service (NTIS)

The Wide Field Infrared Survey Telescope (WFIRST) mission concept was ranked first in new space astrophysics mission by the Astro2010 Decadal Survey incorporating the Joint Dark Energy Mission (JDEM)-Omega payload concept and multiple science white papers...

D. A. Content J. E. Mentzell J. P. Lehan R. Goullioud

2011-01-01

40

The wide-field optical sectioning of microlens array and structured illumination-based plane-projection multiphoton microscopy.  

PubMed

We present a theoretical investigation of an optical microscope design that achieves wide-field, multiphoton fluorescence microscopy with finer axial resolution than confocal microscopy. Our technique creates a thin plane of excitation light at the sample using height-staggered microlens arrays (HSMAs), wherein the height staggering of microlenses generate temporal focusing to suppress out-of-focus excitation, and the dense spacing of microlenses enables the implementation of structured illumination technique to eliminate residual out-of-focus signal. We use physical optics-based numerical simulations to demonstrate that our proposed technique can achieve diffraction-limited three-dimensional imaging through a simple optical design. PMID:23389190

Yu, Jiun-Yann; Holland, Daniel B; Blake, Geoffrey A; Guo, Chin-Lin

2013-01-28

41

Optical design trade study for the Wide Field Infrared Survey Telescope [WFIRST  

NASA Astrophysics Data System (ADS)

The Wide Field Infrared Survey Telescope (WFIRST) mission concept was ranked first in new space astrophysics mission by the Astro2010 Decadal Survey incorporating the Joint Dark Energy Mission (JDEM)-Omega payload concept and multiple science white papers. This mission is based on a space telescope at L2 studying exoplanets (via gravitational microlensing), probing dark energy, and surveying the near infrared sky. Since the release of NWNH, the WFIRST project has been working with the WFIRST science definition team (SDT) to refine mission and payload concepts. We present the driving requirements. The current interim reference mission point design, based on the use of a 1.3m unobscured aperture three mirror anastigmat form, with focal imaging and slitless spectroscopy science channels, is consistent with the requirements, requires no technology development, and out performs the JDEM-Omega design.

Content, D. A.; Goullioud, R.; Lehan, J. P.; Mentzell, J. E.

2011-09-01

42

Removing static aberrations from the active optics system of a wide-field telescope.  

PubMed

The wavefront sensor in active and adaptive telescopes is usually not in the optical path toward the scientific detector. It may generate additional wavefront aberrations, which have to be separated from the errors due to the telescope optics. The aberrations that are not rotationally symmetric can be disentangled from the telescope aberrations by a series of measurements taken in the center of the field, with the wavefront sensor at different orientation angles with respect to the focal plane. This method has been applied at the VLT Survey Telescope on the ESO Paranal observatory. PMID:22751401

Schipani, Pietro; Noethe, Lothar; Arcidiacono, Carmelo; Argomedo, Javier; Dall'Ora, Massimo; D'Orsi, Sergio; Farinato, Jacopo; Magrin, Demetrio; Marty, Laurent; Ragazzoni, Roberto; Umbriaco, Gabriele

2012-07-01

43

Wide-Field Spectral-Domain Optical Coherence Tomography in Patients and Carriers of X-linked Retinoschisis  

PubMed Central

Purpose To evaluate macular and extramacular retinal anatomy in patients and carriers of X-linked retinoschisis (XLRS) utilizing a wide-field spectral-domain optical coherence tomography (SD-OCT) imaging technique. Design Case series Participants Six XLRS affected males and three XLRS female carriers. Methods The subjects prospectively underwent XLRS DNA genotyping and comprehensive ophthalmic examination including Visual acuity, 30-2 Humphrey visual field, fundus photography, and wide-field SD-OCT, a montage technique to generate SD-OCT images spanning approximately 50° horizontally and 35° vertically of the posterior pole. Main Outcome Measures distribution and location of schisis cavities Results Among affected XLRS males, asymmetric bilateral schisis was seen in all eyes imaged with montage SD-OCT (11 eyes). Wide-field OCT images demonstrated schisis cavities only in the central macula in 6 eyes (55%), throughout the macula extending to the outside of the temporal arcades in 3 eyes (27%), and throughout the macula extending nasal to the optic nerve in 2 eyes (18%). Cystoid spaces accounting for macular splitting were present in the inner nuclear layer (INL) in all 11 eyes and also in the outer nuclear layer (ONL) in 4 eyes. A few small cysts were seen parafoveally in the ganglion cell layer and/or nerve fiber layer (GCL/NFL) in 4 eyes. Subclinical extramacular schisis spaces were seen (n=5 eyes) within the INL in 1 eye, ONL in 1 eye, INL/GCL/NFL in 1 eye, ONL/GCL/NFL in 1 eye, and in the INL/ONL/GCL/NFL in 1 eye. Schisis was rarely seen nasal to the optic nerve (2 eyes). Central/paracentral visual field defects were seen in 9 eyes. Female carriers did not show schisis on exam or OCT. Conclusions Wide-field SD-OCT is a useful tool for evaluating complex retinal anatomy. In XLRS patients, the foveomacular schisis was seen most frequently in the INL. Subclinical extramacular schisis was seen in 45% eyes and was equally prevalent in the INL, ONL, and GCL/FNL. GCL/FNL cystoid spaces were very small and were seen near the fovea and the arcades only. Carriers were schisis-free.

Gregori, Ninel Z.; Lam, Byron L.; Gregori, Giovanni; Ranganathan, Sudarshan; Stone, Edwin M.; Morante, Alexis; Abukhalil, Fawzi; Aroucha, Potyra R.

2012-01-01

44

Design of a four-mirror optical system with wide field of view  

NASA Astrophysics Data System (ADS)

Reflective optics is used widely in space optical systems for their achromatization, large aperture and lightweight compared with refractive systems. Four-mirror system especially off-axis system is desired for its excellent imaging performance and compact structure. Aberration theory of coaxial four-mirror system based on PW method is analyzed and the design procedure is proposed to get the initial four-mirror system in this paper. A large field off-axis four-mirror system is designed based on the theory and the design process. The system contains four conic aspheric mirrors. It has a 2°×0.32° rectangular field of view. The MTF of the system is diffraction-limited and the distortion is less than 0.1%. The structure of the system is compact and the ratio of total axis length to focal length is about 1/3.9. The excellent imaging performance and compact structure make it adaptable to space remote sensing systems.

Liang, Shi-Tong; Yang, Jian-Feng; Xue, Bin; Ruan, Ping

2010-11-01

45

Wide Field Planetary Camera 2 Observations of the Brown Dwarf Gliese 229B: Optical Colors and Orbital Motion  

NASA Astrophysics Data System (ADS)

Three-epoch observations of the M1 V-plus-brown dwarf system Gliese 229AB using the Hubble Space Telescope's Wide Field Planetary Camera 2 (WFPC2) are reported. Relative astrometric measurements spanning 1 year confirm the common proper motion of the pair and reveal the first evidence of orbital motion. The radial and azimuthal components of Gl 229B's relative motion are -0.087" and +0.049", respectively, indicating an elliptical orbit rather than an inclined circular orbit. The absolute WFPC2 magnitudes of Gl 229B are M_1042 = 16.37, M_814 = 20.76, and M_675 = 24.60, assuming a distance of 5.774 pc. The detection of Gl 229B through the F675W bandpass is the first reported at R-band wavelengths. The measured flux through F1042M (lambda_c ~ 1 ?m) is well matched by the latest models of dust-free brown dwarf photospheres by Tsuji et al. These models severely overestimate the broadband fluxes shortward of 0.8 mum, however, which indicates that a strong source of optical continuum opacity exists in the photosphere of Gl 229B. A search for fainter companions to Gl 229A in the Planetary Camera was negative to limiting absolute magnitudes of M_1042 ~ 19 and M_814 ~ 24.5 beyond 7" of Gl 229A. Nondetection limits for the Wide Field Cameras are 1.5 mag greater than those for the Planetary Camera.

Golimowski, D. A.; Burrows, C. J.; Kulkarni, S. R.; Oppenheimer, B. R.; Brukardt, R. A.

1998-06-01

46

Mechanical setup for optical aperture synthesis for wide-field imaging  

NASA Astrophysics Data System (ADS)

Homothetic mapping is a technique that combines the images from several telescopes so that it looks like as though they came form a single large telescope. This technique enables a much wider interferometric field of image than current techniques can provide. To investigate the feasibility, a research testbed is build know as Delft Testbed interferometer (DTI). DTI simulates a configuration of three telescopes collecting light of a set of 3 stars. The stars are simulated by coupling light of a Xenon light source into three fibres, which illuminate a parabolic mirror. The light that is used has wavelengths of 500 nm - 800 nm. The light of the three telescopes will be combined in such a way that the beam arrangement in the pupil plane corresponds with the telescope arrangement and the Optical Path Difference (OPD) is minimized for the three beams. To achieve white light fringes with high visibility, the mechanical testbed that is 2 m x 1 m x 0.5 m in size, requires stable mounting of components. This paper describes the mounting of the diamond turned off-axis parabolic mirrors of 200 mm in diameter and 240 mm flat mirrors; furthermore, it describes components like the telescopes and the active controllable components for repositioning of the beam arrangement. Mechanisms were developed for alignment of piezo actuators and for delay lines. The delay lines can also be used to compensate pupil rotation. Test results demonstrate that the test setup is highly stable for temperature as well as for airflow, although the system is placed in a non-thermally controlled lab. This allows measurements of nm, in presence of ?m disturbances.

Giesen, Peter; Ouwerkerk, Bas; van Brug, Hedser; van den Dool, Teun C.; van der Avoort, Casper

2004-10-01

47

Adaptive optics wide-field microscope corrections using a MEMS DM and Shack-Hartmann wavefront sensor  

NASA Astrophysics Data System (ADS)

We demonstrated the used of an adaptive optic system in biological imaging to improve the imaging characteristics of a wide field microscope. A crimson red fluorescent bead emitting light at 650 nm was used together with a Shack-Hartmann wavefront sensor and deformable mirror to compensate for the aberrations introduce by a Drosophila embryo. The measurement and correction at one wavelength improves the resolving power at a different wavelength, enabling the structure of the sample to be resolved (510 nm). The use of the crimson beads allow for less photobleaching to be done to the science object of the embryo, in this case our GFP model (green fluorescent beads), and allows for the science object and wavefront reference to be spectrally separated. The spectral separation allows for single points sources to be used for wavefront measurements, which is a necessary condition for the Shack-Hartmann Wavefront sensor operation.

Azucena, Oscar; Tao, Xiaodong; Crest, Justin; Kotadia, Shaila; Sullivan, William; Gavel, Donald; Reinig, Marc; Olivier, Scot; Kubby, Joel

2011-02-01

48

Andromeda (M31) Optical and Infrared Disk Survey. I. Insights in Wide-field Near-IR Surface Photometry  

NASA Astrophysics Data System (ADS)

We present wide-field near-infrared J and Ks images of the Andromeda Galaxy (M31) taken with WIRCam at the Canada-France-Hawaii Telescope as part of the Andromeda Optical and Infrared Disk Survey. This data set allows simultaneous observations of resolved stars and near-infrared (NIR) surface brightness across M31's entire bulge and disk (within R = 22 kpc), permitting a direct test of the stellar composition of near-infrared light in a nearby galaxy. Here we develop NIR observation and reduction methods to recover a uniform surface brightness map across the 3° × 1° disk of M31 with 27 WIRCam fields. Two sky-target nodding strategies are tested, and we find that strictly minimizing sky sampling latency cannot improve background subtraction accuracy to better than 2% of the background level due to spatio-temporal variations in the NIR skyglow. We fully describe our WIRCam reduction pipeline and advocate using flats built from night-sky images over a single night, rather than dome flats that do not capture the WIRCam illumination field. Contamination from scattered light and thermal background in sky flats has a negligible effect on the surface brightness shape compared to the stochastic differences in background shape between sky and galaxy disk fields, which are ~0.3% of the background level. The most dramatic calibration step is the introduction of scalar sky offsets to each image that optimizes surface brightness continuity. Sky offsets reduce the mean surface brightness difference between observation blocks from 1% to <0.1% of the background level, though the absolute background level remains statistically uncertain to 0.15% of the background level. We present our WIRCam reduction pipeline and performance analysis to give specific recommendations for the improvement of NIR wide-field imaging methods.

Sick, Jonathan; Courteau, Stéphane; Cuillandre, Jean-Charles; McDonald, Michael; de Jong, Roelof; Tully, R. Brent

2014-05-01

49

Instrumentation of LOTIS: Livermore Optical Transient Imaging System; a fully automated wide field of view telescope system searching for simultaneous optical counterparts of gamma ray bursts  

SciTech Connect

LOTIS is a rapidly slewing wide-field-of-view telescope which was designed and constructed to search for simultaneous gamma-ray burst (GRB) optical counterparts. This experiment requires a rapidly slewing ({lt} 10 sec), wide-field-of-view ({gt} 15{degrees}), automatic and dedicated telescope. LOTIS utilizes commercial tele-photo lenses and custom 2048 x 2048 CCD cameras to view a 17.6 x 17.6{degrees} field of view. It can point to any part of the sky within 5 sec and is fully automated. It is connected via Internet socket to the GRB coordinate distribution network which analyzes telemetry from the satellite and delivers GRB coordinate information in real-time. LOTIS started routine operation in Oct. 1996. In the idle time between GRB triggers, LOTIS systematically surveys the entire available sky every night for new optical transients. This paper will describe the system design and performance.

Park, H.S.; Ables, E.; Barthelmy, S.D.; Bionta, R.M.; Ott, L.L.; Parker, E.L.; Williams, G.G.

1998-03-06

50

O-6 Optical Property Degradation of the Hubble Space Telescope's Wide Field Camera-2 Pick Off Mirror  

NASA Technical Reports Server (NTRS)

Degradation in the performance of optical components can be greatly affected by exposure to the space environment. Many factors can contribute to such degradation including surface contaminants; outgassing; vacuum, UV, and atomic oxygen exposure; temperature cycling; or combinations of parameters. In-situ observations give important clues to degradation processes, but there are relatively few opportunities to correlate those observations with post-flight ground analyses. The return of instruments from the Hubble Space Telescope (HST) after its final servicing mission in May 2009 provided such an opportunity. Among the instruments returned from HST was the Wide-Field Planetary Camera-2 (WFPC-2), which had been exposed to the space environment for 16 years. This work focuses on the identifying the sources of degradation in the performance of the Pick-off mirror (POM) from WFPC-2. Techniques including surface reflectivity measurements, spectroscopic ellipsometry, FTIR (and ATR-FTIR) analyses, SEM/EDS, X-ray photoelectron spectroscopy (XPS) with and without ion milling, and wet and dry physical surface sampling were performed. Destructive and contact analyses took place only after completion of the non-destructive measurements. Spectroscopic ellipsometry was then repeated to determine the extent of contaminant removal by the destructive techniques, providing insight into the nature and extent of polymerization of the contaminant layer.

McNamara, Karen M.; Hughes, D. W.; Lauer, H. V.; Burkett, P. J.; Reed, B. B.

2011-01-01

51

Wide field of view telescope  

DOEpatents

A wide field of view telescope having two concave and two convex reflective surfaces, each with an aspheric surface contour, has a flat focal plane array. Each of the primary, secondary, tertiary, and quaternary reflective surfaces are rotationally symmetric about the optical axis. The combination of the reflective surfaces results in a wide field of view in the range of approximately 3.8.degree. to approximately 6.5.degree.. The length of the telescope along the optical axis is approximately equal to or less than the diameter of the largest of the reflective surfaces.

Ackermann, Mark R. (Albuquerque, NM); McGraw, John T. (Placitas, NM); Zimmer, Peter C. (Albuquerque, NM)

2008-01-15

52

Aerosol variability in the Adriatic Sea from automated optical field measurements and Sea-viewing Wide Field-of-view Sensor (SeaWiFS)  

Microsoft Academic Search

The aerosol optical properties in the Adriatic Sea are presented using a 9-year time series (1996–2005) of automated measurements collected on the Acqua Alta Oceanographic Tower (AAOT) in the northern part of the basin and a coincident satellite record obtained from an atmospheric correction scheme adapted for European seas and applied to the Sea-viewing Wide Field-of-view Sensor (SeaWiFS). At AAOT,

F. Mélin; M. Clerici; G. Zibordi; B. Bulgarelli

2006-01-01

53

High-resolution wide-field microscopy with adaptive optics for spherical aberration correction and motionless focusing  

PubMed Central

Summary Live imaging in cell biology requires three-dimensional data acquisition with the best resolution and signal-to-noise ratio possible. Depth aberrations are a major source of image degradation in three-dimensional microscopy, causing a significant loss of resolution and intensity deep into the sample. These aberrations occur because of the mismatch between the sample refractive index and the immersion medium index. We have built a wide-field fluorescence microscope that incorporates a large-throw deformable mirror to simultaneously focus and correct for depth aberration in three-dimensional imaging. Imaging fluorescent beads in water and glycerol with an oil immersion lens we demonstrate a corrected point spread function and a 2-fold improvement in signal intensity. We apply this new microscope to imaging biological samples, and show sharper images and improved deconvolution.

Sedat, J.W.; Agard, D.A.; Kam, Z.

2010-01-01

54

Wide-Field Plate Database  

NASA Astrophysics Data System (ADS)

The Wide-Field Plate Database (WFPDB) and the possibilities for its application as a research tool in observational astronomy are presented. Currently the WFPDB comprises the descriptive data for 400 000 archival wide field photographic plates obtained with 77 instruments, from a total of 1 850 000 photographs stored in 269 astronomical archives all over the world since the end of last century. The WFPDB is already accessible for the astronomical community, now only in batch mode through user requests sent by e-mail. We are working on on-line interactive access to the data via INTERNET from Sofia and parallel from the Centre de Donnees Astronomiques de Strasbourg. (Initial information can be found on World Wide Web homepage URL http://www.wfpa.acad.bg.) The WFPDB may be useful in studies of a variety of astronomical objects and phenomena, andespecially for long-term investigations of variable objects and for multi-wavelength research. We have analysed the data in the WFPDB in order to derive the overall characteristics of the totality of wide-field observations, such as the sky coverage, the distributions by observation time and date, by spectral band, and by object type. We have also examined the totality of wide-field observations from point of view of their quality, availability and digitisation. The usefulness of the WFPDB is demonstrated by the results of identification and investigation of the photometrical behaviour of optical analogues of gamma-ray bursts.

Tsvetkov, M. K.; Stavrev, K. Y.; Tsvetkova, K. P.; Semkov, E. H.; Mutatov, A. S.

55

Optomechanical design concept for GMACS: a wide-field multi-object moderate resolution optical spectrograph for the Giant Magellan Telescope (GMT)  

NASA Astrophysics Data System (ADS)

We describe the conceptual optomechanical design for GMACS, a wide-field, multi-object, moderate-resolution optical spectrograph for the Giant Magellan Telescope (GMT). GMACS is a candidate first-light instrument for the GMT and will be one of several instruments housed in the Gregorian Instrument Rotator (GIR) located at the Gregorian focus. The instrument samples a 9 arcminute x 18 arcminute field of view providing two resolution modes (i.e, low resolution, R ~ 2000, and moderate resolution, R ~ 4000) over a 3700 Å to 10200 Å wavelength range. To minimize the size of the optics, four fold mirrors at the GMT focal plane redirect the full field into four individual "arms", that each comprises a double spectrograph with a red and blue channel. Hence, each arm samples a 4.5 arcminute x 9 arcminute field of view. The optical layout naturally leads to three separate optomechanical assemblies: a focal plane assembly, and two identical optics modules. The focal plane assembly contains the last element of the telescope's wide-field corrector, slit-mask, tent-mirror assembly, and slit-mask magazine. Each of the two optics modules supports two of the four instrument arms and houses the aft-optics (i.e. collimators, dichroics, gratings, and cameras). A grating exchange mechanism, and articulated gratings and cameras facilitate multiple resolution modes. In this paper we describe the details of the GMACS optomechanical design, including the requirements and considerations leading to the design, mechanism details, optics mounts, and predicted flexure performance.

Smee, Stephen A.; Prochaska, Travis; Shectman, Stephen A.; Hammond, Randolph P.; Barkhouser, Robert H.; DePoy, D. L.; Marshall, J. L.

2012-09-01

56

Wide-field optical detection of nanoparticles using on-chip microscopy and self-assembled nanolenses  

PubMed Central

The direct observation of nanoscale objects is a challenging task for optical microscopy because the scattering from an individual nanoparticle is typically weak at optical wavelengths. Electron microscopy therefore remains one of the gold standard visualization methods for nanoparticles, despite its high cost, limited throughput and restricted field-of-view. Here, we describe a high-throughput, on-chip detection scheme that uses biocompatible wetting films to self-assemble aspheric liquid nanolenses around individual nanoparticles to enhance the contrast between the scattered and background light. We model the effect of the nanolens as a spatial phase mask centred on the particle and show that the holographic diffraction pattern of this effective phase mask allows detection of sub-100 nm particles across a large field-of-view of >20 mm2. As a proof-of-concept demonstration, we report on-chip detection of individual polystyrene nanoparticles, adenoviruses and influenza A (H1N1) viral particles.

Mudanyali, Onur; McLeod, Euan; Luo, Wei; Greenbaum, Alon; Coskun, Ahmet F.; Hennequin, Yves; Allier, Cedric P.; Ozcan, Aydogan

2013-01-01

57

On-Sky Wide-Field Adaptive Optics Correction Using Multiple Laser Guide Stars at the MMT  

NASA Astrophysics Data System (ADS)

We describe results from the first astronomical adaptive optics (AO) system to use multiple laser guide stars, located at the 6.5 m MMT telescope in Arizona. Its initial operational mode, ground-layer adaptive optics (GLAO), provides uniform stellar wave front correction within the 2' diameter laser beacon constellation, reducing the stellar image widths by as much as 53%, from 0farcs70 to 0farcs33 at ? = 2.14 ?m. GLAO is achieved by applying a correction to the telescope's adaptive secondary mirror that is an average of wave front measurements from five laser beacons supplemented with image motion from a faint stellar source. Optimization of the AO system in subsequent commissioning runs will further improve correction performance where it is predicted to deliver 0farcs1-0farcs2 resolution in the near-infrared during a majority of seeing conditions.

Baranec, Christoph; Hart, Michael; Milton, N. Mark; Stalcup, Thomas; Powell, Keith; Snyder, Miguel; Vaitheeswaran, Vidhya; McCarthy, Don; Kulesa, Craig

2009-03-01

58

Wide-field optical detection of nanoparticles using on-chip microscopy and self-assembled nanolenses  

NASA Astrophysics Data System (ADS)

The direct observation of nanoscale objects is a challenging task for optical microscopy because the scattering from an individual nanoparticle is typically weak at optical wavelengths. Electron microscopy therefore remains one of the gold standard visualization methods for nanoparticles, despite its high cost, limited throughput and restricted field-of-view. Here, we describe a high-throughput, on-chip detection scheme that uses biocompatible wetting films to self-assemble aspheric liquid nanolenses around individual nanoparticles to enhance the contrast between the scattered and background light. We model the effect of the nanolens as a spatial phase mask centred on the particle and show that the holographic diffraction pattern of this effective phase mask allows detection of sub-100 nm particles across a large field-of-view of >20 mm2. As a proof-of-concept demonstration, we report on-chip detection of individual polystyrene nanoparticles, adenoviruses and influenza A (H1N1) viral particles.

Mudanyali, Onur; McLeod, Euan; Luo, Wei; Greenbaum, Alon; Coskun, Ahmet F.; Hennequin, Yves; Allier, Cédric P.; Ozcan, Aydogan

2013-03-01

59

Future Optical Networks  

NASA Astrophysics Data System (ADS)

This paper presents views on the future of optical networking. A historical look at the emergence of optical networking is first taken, followed by a discussion on the drivers pushing for a new and pervasive network, which is based on photonics and can satisfy the needs of a broadening base of residential, business, and scientific users. Regional plans and targets for optical networking are reviewed to understand which current approaches are judged important. Today, two thrusts are driving separate optical network infrastructure models, namely 1) the need by nations to provide a ubiquitous network infrastructure to support all the future services and telecommunication needs of residential and business users and 2) increasing demands by the scientific community for networks to support their requirements with respect to large-scale data transport and processing. This paper discusses these network models together with the key enabling technologies currently being considered for future implementation, including optical circuit, burst and packet switching, and optical code-division multiplexing. Critical subsystem functionalities are also reviewed. The discussion considers how these separate models might eventually merge to form a global optical network infrastructure.

O'Mahony, Michael J.; Politi, Christina; Klonidis, Dimitrios; Nejabati, Reza; Simeonidou, Dimitra

2006-12-01

60

A Wide-Field Narrowband Optical Survey of the Braid Nebula Star Formation Region in Cygnus OB7  

NASA Astrophysics Data System (ADS)

We study the population of Herbig-Haro (HH) flows and jets in an area of Cygnus OB7 designated the Braid Nebula star formation region. This complex forms part of the L 1003 dark cloud, and hosts two FU Orionis (FUor)-like objects as well as several other active young stars. To trace outflow activity and to relate both known and newly discovered flows to young star hosts we intercompare new, deep, narrowband H? and [S II] optical images taken on the Subaru 8 m Telescope on Mauna Kea, Hawaii. Our images show that there is considerable outflow and jet activity in this region suggesting the presence of an extensive young star population. We confirm that both of the FUor-like objects drive extensive HH flows and document further members of the flows in both objects. The L 1003 star formation complex is a highly kinematically active region with young stars in several different stages of evolution. We trace collimated outflows from numerous young stars although the origin of some HH objects remains elusive. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Magakian, Tigran Yu.; Nikogossian, Elena H.; Aspin, Colin; Pyo, Tae-Soo; Khanzadyan, Tigran; Movsessian, Tigran; Smith, Michael D.; Mitchison, Sharon; Davis, Chris J.; Beck, Tracy L.; Moriarty-Schieven, Gerald H.

2010-03-01

61

A WIDE-FIELD NARROWBAND OPTICAL SURVEY OF THE BRAID NEBULA STAR FORMATION REGION IN CYGNUS OB7  

SciTech Connect

We study the population of Herbig-Haro (HH) flows and jets in an area of Cygnus OB7 designated the Braid Nebula star formation region. This complex forms part of the L 1003 dark cloud, and hosts two FU Orionis (FUor)-like objects as well as several other active young stars. To trace outflow activity and to relate both known and newly discovered flows to young star hosts we intercompare new, deep, narrowband H{alpha} and [S II] optical images taken on the Subaru 8 m Telescope on Mauna Kea, Hawaii. Our images show that there is considerable outflow and jet activity in this region suggesting the presence of an extensive young star population. We confirm that both of the FUor-like objects drive extensive HH flows and document further members of the flows in both objects. The L 1003 star formation complex is a highly kinematically active region with young stars in several different stages of evolution. We trace collimated outflows from numerous young stars although the origin of some HH objects remains elusive.

Magakian, Tigran Yu.; Nikogossian, Elena H.; Movsessian, Tigran [Byurakan Astrophysical Observatory, 378433 Aragatsotn reg. (Armenia); Aspin, Colin [Institute for Astronomy, University of Hawaii, 640 North A'ohoku Place, Hilo, HI, 96720 (United States); Pyo, Tae-Soo [Subaru Telescope, National Astronomical Observatory of Japan, 650 North A'ohoku Place, Hilo, HI 96720 (United States); Khanzadyan, Tigran [Centre for Astronomy, School of Physics, National University of Ireland Galway, University Road, Galway (Ireland); Smith, Michael D.; Mitchison, Sharon [Centre for Astrophysics and Planetary Science, School of Physical Sciences, University of Kent, Canterbury CT2 7NR (United Kingdom); Davis, Chris J. [Joint Astronomy Centre, 660 North A'ohoku Place, University Park, Hilo, Hawaii 96720 (United States); Beck, Tracy L. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Moriarty-Schieven, Gerald H. [NRC Herzberg Institute of Astrophysics, 5071 West Saanich Road Victoria, British Columbia, V9E 2E7 (Canada)], E-mail: tigmag@sci.am, E-mail: elena@bao.sci.am, E-mail: caa@ifa.hawaii.edu, E-mail: pyo@subaru.naoj.org, E-mail: tigran.khanzadyan@nuigalway.ie, E-mail: smm23@kent.ac.uk, E-mail: m.d.smith@kent.ac.uk, E-mail: c.davis@jach.hawaii.edu, E-mail: tbeck@stsci.edu, E-mail: gerald.schieven@nrc-cnrc.gc.ca

2010-03-15

62

Simulator sickness when performing gaze shifts within a wide field of view optic flow environment: preliminary evidence for using virtual reality in vestibular rehabilitation  

PubMed Central

Background Wide field of view virtual environments offer some unique features that may be beneficial for use in vestibular rehabilitation. For one, optic flow information extracted from the periphery may be critical for recalibrating the sensory processes used by people with vestibular disorders. However, wide FOV devices also have been found to result in greater simulator sickness. Before a wide FOV device can be used in a clinical setting, its safety must be demonstrated. Methods Symptoms of simulator sickness were recorded by 9 healthy adult subjects after they performed gaze shifting tasks to locate targets superimposed on an optic flow background. Subjects performed 8 trials of gaze shifting on each of the six separate visits. Results The incidence of symptoms of simulator sickness while subjects performed gaze shifts in an optic flow environment was lower than the average reported incidence for flight simulators. The incidence was greater during the first visit compared with subsequent visits. Furthermore, the incidence showed an increasing trend over the 8 trials. Conclusion The performance of head unrestrained gaze shifts in a wide FOV optic flow environment is tolerated well by healthy subjects. This finding provides rationale for testing these environments in people with vestibular disorders, and supports the concept of using wide FOV virtual reality for vestibular rehabilitation.

Sparto, Patrick J; Whitney, Susan L; Hodges, Larry F; Furman, Joseph M; Redfern, Mark S

2004-01-01

63

Wide-field optical imaging on ELAIS N1, ELAIS N2, First Look Survey and Lockman Hole: observations and source catalogues  

NASA Astrophysics Data System (ADS)

We present u-, g-, r-, i- and z-band optical images and associated catalogues taken primarily with the Isaac Newton Telescope Wide Field Camera on the European Large Area ISO Survey (ELAIS) N1 and N2, First Look Survey and Lockman Hole fields comprising a total of 1000 h of integration time over 80 deg2 and approximately 4.3 million objects. In this paper we outline the observations and data processing and characterize the completeness, reliability, photometric and astrometric accuracy of this data set. All images have been photometrically calibrated using the Sloan Digital Sky Survey and a uniform and homogeneous data set is composed over all the observed fields. Magnitude limits are u, g, r, i, z of 23.9, 24.5, 24.0, 23.3, 22.0 (AB, 5?). These data have been used for optical identification of past and ongoing projects including the surveys ELAIS, Spitzer Wide-Area Infrared Extragalactic Survey, Spitzer Extragalactic Representative Volume Survey and Herschel Multi-tiered Extragalactic Survey.

González-Solares, E. A.; Irwin, M.; McMahon, R. G.; Hodgkin, S.; Lewis, J. R.; Walton, N. A.; Jarvis, M.; Marchetti, L.; Oliver, S.; Pérez-Fournon, I.; Siana, B.; Surace, J.; Vaccari, M.

2011-09-01

64

Probing the Physical Properties of High Redshift Optically Obscured Galaxies in the Bootes NOAO Deep Wide Field Survey using the Infrared Spectrograph on Spitzer  

NASA Astrophysics Data System (ADS)

We have surveyed a field covering 8.4 degrees2 within the NOAO Deep Wide Field Survey region in Boötes with the Multiband Imaging Photometer on the Spitzer Space Telescope to a limiting 24 um flux density of 0.3 mJy, identifying ˜ 22,000 point sources. Thirty one sources from this survey with F(24 um) > 0.75 mJy , which are optically ``invisible'' (R > 26) or very faint (I > 24) have been observed with the low-resolution modules of the Infrared Spectrograph on SST. The spectra were extracted using the IRS SMART spectral analysis package in order to optimize their signal to noise. A suite of mid-IR spectral templates of well known galaxies, observed as part of the IRS GTO program, is used to perform formal fits to the spectral energy distribution of the Boötes sources. These fits enable us to measure their redshift, to calculate the depth of the 9.7 um silicate feature along with the strength of 7.7 um PAH, as well as to estimate their bolometric luminosities. We compare the mid-IR slope, the measured PAH luminosity, and the optical depth of these sources with those of galaxies in the local Universe. As a result we are able to estimate the contribution of a dust enshrouded active nucleus to the mid-IR and bolometric luminosity of these systems. This work is based [in part] on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407. Support for this work was provided by NASA through Contract Number 1257184 issued by JPL/Caltech.

Higdon, S. J. U.; Weedman, D.; Higdon, J. L.; Houck, J. R.; Soifer, B. T.; Armus, L.; Charmandaris, V.; Herter, T. L.; Brandl, B. R.; Brown, M. J. I.; Dey, A.; Jannuzi, B.; Le Floc'h, E.; Rieke, M.

2004-12-01

65

Imaging spectrometer wide field catadioptric design  

Microsoft Academic Search

A wide field catadioptric imaging spectrometer with an immersive diffraction grating that compensates optical distortions. The catadioptric design has zero Petzval field curvature. The imaging spectrometer comprises an entrance slit for transmitting light, a system with a catadioptric lens and a dioptric lens for receiving the light and directing the light, an immersion grating, and a detector array. The entrance

Chrisp; Michael P

2008-01-01

66

Wide field x-ray telescope mission  

NASA Astrophysics Data System (ADS)

The Wide Field X-Ray Telescope (WFXT) will carry out an unprecedented X-ray survey of galaxy clusters and groups, AGNs and QSOs, and galaxies. WFXT is a medium-class strategic mission that will address key questions in both Cosmic Origins and Physics of the Cosmos. WFXT will be orders of magnitude more effective than previous X-ray missions in performing surveys to a given limiting flux. The angular resolution of ~5" will be finer than provided by any currently planned large-area X-ray survey and highly efficient at discriminating AGNs and QSOs from extended emission from sources such as galaxies and clusters. The Burrows, Burg and Giacconi ideal optical solution gives an approximately constant angular resolution of 3-5 arc seconds across a field of 1-1.5 degrees diameter. A preliminary telescope design provides a resulting grasp an order of magnitude larger than current or future missions. We plan a combination of three surveys and, at each flux limit, WFXT will cover orders of magnitude more area than all previous and planned missions, with the deep 100 deg2 survey reaching the same flux limit as the deepest Chandra surveys to date. The WFXT mission addresses key cosmological and astrophysical science objectives including: the formation and evolution of clusters of galaxies with the associated cosmological and astrophysical implications; black hole formation and evolution; the interaction of black-hole driven AGNs with cluster and galaxy properties; and the high-energy stellar component and the hot ISM phase of galaxies WFXT is a mission for the entire astronomical community. The data from these surveys will be made readily available to the community in timely data releases to be used in a multitude of multi-waveband studies that will revolutionize astronomy.

Murray, Stephen S.; Norman, Colin; Ptak, Andrew; Giacconi, Riccardo; Weisskopf, Martin; Ramsey, Brian; Bautz, Mark; Vikhliniin, Alexey; Brandt, Niel; Rosati, Piero; Weaver, Harold; Allen, Steve; Flanagan, Kathryn

2008-07-01

67

The XMM-Newton Wide-Field Survey in the COSMOS Field. III. Optical Identification and Multiwavelength Properties of a Large Sample of X-Ray-Selected Sources  

NASA Astrophysics Data System (ADS)

We present the optical identification of a sample of 695 X-ray sources detected in the first 1.3 deg2 of the COSMOS XMM-Newton survey, down to a 0.5-2 keV (2-10 keV) limiting flux of ~10-15 erg cm-2 s-1 (~5×10-15 erg cm-2 s-1). In order to identify the correct optical counterparts and to assess the statistical significance of the X-ray-to-optical associations we have used the ``likelihood ratio technique.'' Here we present the identification method and its application to the CFHT I-band and photometric catalogs. We were able to associate a candidate optical counterpart to ~90% (626) of the X-ray sources, while for the remaining ~10% of the sources we were not able to provide a unique optical association due to the faintness of the possible optical counterparts (IAB>25) or to the presence of multiple optical sources, with similar likelihoods of being the correct identification, within the XMM-Newton error circles. We also cross-correlated the candidate optical counterparts with the Subaru multicolor and ACS catalogs and with the Magellan/IMACS, zCOSMOS, and literature spectroscopic data; the spectroscopic sample comprises 248 objects (~40% of the full sample). Our analysis of this statistically meaningful sample of X-ray sources reveals that for ~80% of the counterparts there is a very good agreement between the spectroscopic classification, the morphological parameters as derived from ACS data, and the optical-to-near-infrared colors: the large majority of spectroscopically identified broad-line active galactic nuclei (BL AGNs) have a pointlike morphology on ACS data, blue optical colors in color-color diagrams, and an X-ray-to-optical flux ratio typical of optically selected quasars. Conversely, sources classified as narrow line AGNs or normal galaxies are on average associated with extended optical sources, have significantly redder optical-to-near-infrared colors, and span a larger range of X-ray-to-optical flux ratios. However, about 20% of the sources show an apparent mismatch between the morphological and spectroscopic classifications. All the ``extended'' BL AGNs lie at redshift <1.5, while the redshift distribution of the full BL AGN population peaks at z~1.5. The most likely explanation is that in these objects the nuclear emission is not dominant with respect to the host galaxy emission in the observed ACS band. Our analysis also suggests that the type 2/type 1 ratio decreases toward high luminosities, in qualitative agreement with the results from X-ray spectral analysis and the most recent modeling of the X-ray luminosity function evolution. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA; also based on data collected at the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. (AURA), under NASA contract NAS 5-26555 the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; the European Southern Observatory, Chile, under Large Program 175.A-0839 Kitt Peak National Observatory, Cerro Tololo Inter-American Observatory, and the National Optical Astronomy Observatory, which are operated by the Association of Universities for Research in Astronomy, Inc. (AURA), under cooperative agreement with the National Science Foundation; and the Canada-France-Hawaii Telescope operated by the National Research Council of Canada, the Centre National de la Recherche Scientifique de France and the University of Hawaii.

Brusa, M.; Zamorani, G.; Comastri, A.; Hasinger, G.; Cappelluti, N.; Civano, F.; Finoguenov, A.; Mainieri, V.; Salvato, M.; Vignali, C.; Elvis, M.; Fiore, F.; Gilli, R.; Impey, C. D.; Lilly, S. J.; Mignoli, M.; Silverman, J.; Trump, J.; Urry, C. M.; Bender, R.; Capak, P.; Huchra, J. P.; Kneib, J. P.; Koekemoer, A.; Leauthaud, A.; Lehmann, I.; Massey, R.; Matute, I.; McCarthy, P. J.; McCracken, H. J.; Rhodes, J.; Scoville, N. Z.; Taniguchi, Y.; Thompson, D.

2007-09-01

68

FEL optics - present and future  

SciTech Connect

As free-electron lasers advance to both higher average powers and shorter wavelengths, the requirements on the optical system become more and more stringent. In this paper, the physical reasoning behind these requirements and how they are met in both current and proposed oscillators are examined. The cavity being used in a current FEL experiment will be considered in some detail. Future glancing incidence ring cavities are also discussed with an emphasis on concept rather than engineering detail. 9 references.

Shemwell, D.M.; Quimby, D.C.; Ross, J.M.; Slater, J.M.; Zumdieck, J.F.

1987-06-01

69

Imaging spectrometer wide field catadioptric design  

DOEpatents

A wide field catadioptric imaging spectrometer with an immersive diffraction grating that compensates optical distortions. The catadioptric design has zero Petzval field curvature. The imaging spectrometer comprises an entrance slit for transmitting light, a system with a catadioptric lens and a dioptric lens for receiving the light and directing the light, an immersion grating, and a detector array. The entrance slit, the system for receiving the light, the immersion grating, and the detector array are positioned wherein the entrance slit transmits light to the system for receiving the light and the system for receiving the light directs the light to the immersion grating and the immersion grating receives the light and directs the light through the system for receiving the light to the detector array.

Chrisp; Michael P. (Danville, CA)

2008-08-19

70

Wide-field Infrared Survey Explorer  

NASA Technical Reports Server (NTRS)

We present WISE (Wide-field Infrared Survey Explorer) mid-infrared photometry of young stellar object candidates in the Canis Majoris clouds at a distance of 1 kpc. WISE has identified 682 objects with apparent 12 and 22 micron excess emission in a 7 deg x 10 deg field around the CMa Rl cloud . While a substantial fraction of these candidates are likely galaxies, AGB stars, and artifacts from confusion along the galactic plane, others are part of a spectacular cluster of YSOs imaged by WISE along a dark filament in the R1 cloud. Palomar Double Spectrograph observations of several sources in this cluster confirm their identity as young A and B stars with strong emission lines. In this contribution, we plot the optical -mid-infrared spectral energy distribution for the WISE YSO candidates and discuss potential contaminants to the sample . The data demonstrate the utility of WISE in performing wide-area surveys for young stellar objects.

Padgett, Deborah

2012-01-01

71

The XUV Wide Field Camera on ROSAT  

NASA Astrophysics Data System (ADS)

The XUV Wide Field Camera is the second instrument on the German ROSAT Observatory. The instrument concept is described, the responses of the XUV mirrors, the microchannel plate detectors and the thin film filters are reviewed and the performance characteristics of the Wide Field Camera are summarised.

Wells, A.

72

Wide Field and Planetary Camera for Space Telescope  

NASA Technical Reports Server (NTRS)

The Space Telescope's Wide Field and Planetary Camera instrument, presently under construction, will be used to map the observable universe and to study the outer planets. It will be able to see 1000 times farther than any previously employed instrument. The Wide Field system will be located in a radial bay, receiving its signals via a pick-off mirror centered on the optical axis of the telescope assembly. The external thermal radiator employed by the instrument for cooling will be part of the exterior surface of the Space Telescope. In addition to having a larger (1200-12,000 A) wavelength range than any of the other Space Telescope instruments, its data rate, at 1 Mb/sec, exceeds that of the other instruments. Attention is given to the operating modes and projected performance levels of the Wide Field Camera and Planetary Camera.

Lockhart, R. F.

1982-01-01

73

Future optical technologies for telescopes  

NASA Astrophysics Data System (ADS)

New optical technologies have revolutionized astronomy, from the invention of the telescope 400 years ago to more recent developments of adaptive optics and segmented mirrors. The next disruptive technologies could well emerge from integrated photonic devices.

Cunningham, Colin

2009-05-01

74

The Spitzer Deep, Wide-field Survey  

Microsoft Academic Search

The Spitzer Deep, Wide-Field Survey (SDWFS) is a four-epoch infrared survey of 10 deg2 in the Boötes field of the NOAO Deep Wide-Field Survey using the IRAC instrument on the Spitzer Space Telescope. SDWFS, a Spitzer Cycle 4 Legacy project, occupies a unique position in the area-depth survey space defined by other Spitzer surveys. The four epochs that make up

M. L. N. Ashby; D. Stern; M. Brodwin; R. Griffith; P. Eisenhardt; S. Kozlowski; C. S. Kochanek; J. J. Bock; C. Borys; K. Brand; M. J. I. Brown; R. Cool; A. Cooray; S. Croft; A. Dey; D. Eisenstein; A. H. Gonzalez; V. Gorjian; N. A. Grogin; R. J. Ivison; J. Jacob; B. T. Jannuzi; A. Mainzer; L. A. Moustakas; H. J. A. Röttgering; N. Seymour; H. A. Smith; S. A. Stanford; J. R. Stauffer; I. Sullivan; W. van Breugel; S. P. Willner; E. L. Wright

2009-01-01

75

Fiber Optics: A Bright Future.  

ERIC Educational Resources Information Center

Presents an overview of the impact of fiber optics on telecommunications and its application to information processing and library services, including information retrieval, news services, remote transmission of library services, and library networking. (RAA)

Rice, James, Jr.

1980-01-01

76

Wide-Field Image Compensation with Multiple Laser Guide Stars  

Microsoft Academic Search

We report closed-loop results obtained from an adaptive optics system with multiple laser guide beacons. The system is mounted on the 6.5 m MMT telescope in Arizona, and is designed to explore advanced altitude-conjugated techniques for wide-field image compensation. Five beacons are made by Rayleigh scattering of laser beams at 532 nm integrated over a range from 20 to 29

M. Hart; N. Milton; K. Powell; C. Baranec; T. Stalcup; D. McCarthy; C. Kulesa

2009-01-01

77

Developing wide-field spatio-spectral interferometry for far-infrared space applications  

NASA Astrophysics Data System (ADS)

Interferometry is an affordable way to bring the benefits of high resolution to space far-IR astrophysics. We summarize an ongoing effort to develop and learn the practical limitations of an interferometric technique that will enable the acquisition of high-resolution far-IR integral field spectroscopic data with a single instrument in a future space-based interferometer. This technique was central to the Space Infrared Interferometric Telescope (SPIRIT) and Submillimeter Probe of the Evolution of Cosmic Structure (SPECS) space mission design concepts, and it will first be used on the Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII). Our experimental approach combines data from a laboratory optical interferometer (the Wide-field Imaging Interferometry Testbed, WIIT), computational optical system modeling, and spatio-spectral synthesis algorithm development. We summarize recent experimental results and future plans.

Leisawitz, David; Bolcar, Matthew R.; Lyon, Richard G.; Maher, Stephen F.; Memarsadeghi, Nargess; Rinehart, Stephen A.; Sinukoff, Evan J.

2012-07-01

78

Developing Wide-Field Spatio-Spectral Interferometry for Far-Infrared Space Applications  

NASA Technical Reports Server (NTRS)

Interferometry is an affordable way to bring the benefits of high resolution to space far-IR astrophysics. We summarize an ongoing effort to develop and learn the practical limitations of an interferometric technique that will enable the acquisition of high-resolution far-IR integral field spectroscopic data with a single instrument in a future space-based interferometer. This technique was central to the Space Infrared Interferometric Telescope (SPIRIT) and Submillimeter Probe of the Evolution of Cosmic Structure (SPECS) space mission design concepts, and it will first be used on the Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII). Our experimental approach combines data from a laboratory optical interferometer (the Wide-field Imaging Interferometry Testbed, WIIT), computational optical system modeling, and spatio-spectral synthesis algorithm development. We summarize recent experimental results and future plans.

Leisawitz, David; Bolcar, Matthew R.; Lyon, Richard G.; Maher, Stephen F.; Memarsadeghi, Nargess; Rinehart, Stephen A.; Sinukoff, Evan J.

2012-01-01

79

Wide field imaging problems in radio astronomy  

NASA Astrophysics Data System (ADS)

The new generation of synthesis radio telescopes now being proposed, designed, and constructed face substantial problems in making images over wide fields of view. Such observations are required either to achieve the full sensitivity limit in crowded fields or for surveys. The Square Kilometre Array (SKA Consortium, Tech. Rep., 2004), now being developed by an international consortium of 15 countries, will require advances well beyond the current state of the art. We review the theory of synthesis radio telescopes for large fields of view. We describe a new algorithm, W projection, for correcting the non-coplanar baselines aberration. This algorithm has improved performance over those previously used (typically an order of magnitude in speed). Despite the advent of W projection, the computing hardware required for SKA wide field imaging is estimated to cost up to $500M (2015 dollars). This is about half the target cost of the SKA. Reconfigurable computing is one way in which the costs can be decreased dramatically.

Cornwell, T. J.; Golap, K.; Bhatnagar, S.

2005-03-01

80

Rozhen Observatory wide-field plate archives  

NASA Astrophysics Data System (ADS)

This paper provides an overview of the wide-field (>10) plate archives at disposal in the Institute of Astronomy and National Astronomical Observatory Rozhen of the Bulgarian Academy of Sciences. The plates with total number 10093 are obtained in the period November 1978 - February 1998 with the 2 m RCC telescope and 50/70/172 cm Schmidt telescope. The available plate catalogues are upgraded with new information, as well as with link to the digitized logbooks (in JPEG file format). The digitization with high quality EPSON flatbed scanners of the available 2 m RCC telescope plates (with low resolution in JPEG, and with high resolution in standardized FITS file format) is accomplished. The digitization of the available 50/70/172 cm Schmidt telescope plates is running. The low resolution images of the scanned Rozhen plates are included in the Wide-Field Plate Database (http://wfpdb.org) and accessible online.

Tsvetkova, K.; Tsvetkov, M.

2013-01-01

81

Design and development of a wide field telescope  

NASA Astrophysics Data System (ADS)

A prototype of large wide field telescope is a Cassegrain telescope which covers 2° field of view with two hyperbolic mirrors, a 0.5 m primary mirror and a 0.2 m secondary mirror with multiple correction lenses. To fulfill the optical and mechanical performance requirements in design and development phase extensive finite element analyses using NX NASTRAN and optical analyses with CODE V and PCFRINGE have been conducted for the structure of optical system. Analyses include static deformation (gravity and thermal), frequency, dynamic response analysis, and optical performance evaluations for minimum optical deformation. Image motion is also calculated based on line of sight sensitivity equations integrated in finite element models. A parametric process was performed for the design optimization to produce highest fundamental frequency for a given weight, as well as to deal with the normal concerns about global performance.

Moon, Il; Lee, Sangon; Lim, Juhee; Yang, Ho-Soon; Rhee, Hyug-Gyo; Song, Jae Bong; Lee, Yun Woo; Lee, Jong Ung; Jin, Ho

2012-09-01

82

Experimental comparison of Wide Field AO control schemes using the Homer AO bench.  

NASA Astrophysics Data System (ADS)

Wide Field Adaptive Optics (WFAO) concepts, such as Laser Tomography AO (LTAO) or Multi-Conjugate AO (MCAO) have been developed in order to overcome the anisoplanatism limit of classical AO. Most of the future AO-assisted instruments of ELTs rely on such concepts which have raised critical challenges such as tomographic estimation and from laser and natural guide star combined with efficient DM(s) control. In that context, the experimental validation of the various clever control solutions proposed by several teams in the past years is now essential to reach a level of maturity compatible with their implementation in future WFAO developments for ELT. The ONERA wide field AO facility (HOMER bench) has been developed for these very issues. Gathering a 3D turbulence generator, laser and natural guide stars, two deformable mirrors with variable altitude positions and a PC-based flexible and user-friendly RTC , HOMER allows the implementation and comparison of control schemes from the simplest least-square to the optimal Linear Quadratic Gaussian solutions including Virtual DM and Pseudo-closed loop approaches. After a description of the bench internal calibrations and ultimate performance, all the control schemes are compared experimentally. Their evolutions as a function of wavefront sensors SNR as well as their robustness to calibration / model errors are particularly emphasised. Finally, we derive from the previous works some specific calibrations and identifications procedures ensuring both robustness and efficiency of WFAO systems and we extrapolate their applications to the future ELT AO systems.

Parisot, Amélie; Petit, Cyril; Fusco, Thierry

2011-09-01

83

Future metrology needs for FEL reflective optics.  

SciTech Connect

An International Workshop on Metrology for X-ray and Neutron Optics has been held March 16-17, 2000, at the Advanced Photon Source, Argonne National Laboratory, near Chicago, Illinois (USA). The workshop gathered engineers and scientists from both the U.S. and around the world to evaluate metrology instrumentation and methods used to characterize surface figure and finish for long grazing incidence optics used in beamlines at synchrotrons radiation sources. This two-day workshop was motivated by the rapid evolution in the performance of x-ray and neutron sources along with requirements in optics figure and finish. More specifically, the performance of future light sources, such as free-electron laser (FEL)-based x-ray sources, is being pushed to new limits in term of both brilliance and coherence. As a consequence, tolerances on surface figure and finish of the next generation of optics are expected to become tighter. The timing of the workshop provided an excellent opportunity to study the problem, evaluate the state of the art in metrology instrumentation, and stimulate innovation on future metrology instruments and techniques to be used to characterize these optics. This paper focuses on FEL optics and metrology needs. (A more comprehensive summary of the workshop can be found elsewhere.) The performance and limitations of current metrology instrumentation will be discussed and recommendations from the workshop on future metrology development to meet the FEL challenges will be detailed.

Assoufid, L.

2000-09-21

84

Revisiting the theory of interferometric wide-field synthesis  

NASA Astrophysics Data System (ADS)

Context. After several generations of interferometers in radioastronomy, wide-field imaging at high angular resolution is today a major goal for trying to match optical wide-field performances. Aims: All the radio-interferometric, wide-field imaging methods currently belong to the mosaicking family. Based on a 30 years old, original idea from Ekers & Rots, we aim at proposing an alternate formalism. Methods: Starting from their ideal case, we successively evaluate the impact of the standard ingredients of interferometric imaging, i.e. the sampling function, the visibility gridding, the data weighting, and the processing of the short spacings either from single-dish antennas or from heterogeneous arrays. After a comparison with standard nonlinear mosaicking, we assess the compatibility of the proposed processing with 1) a method of dealing with the effect of celestial projection and 2) the elongation of the primary beam along the scanning direction when using the on-the-fly observing mode. Results: The dirty image resulting from the proposed scheme can be expressed as a convolution of the sky brightness distribution with a set of wide-field dirty beams varying with the sky coordinates. The wide-field dirty beams are locally shift-invariant as they do not depend strongly on position on the sky: their shapes vary on angular scales typically larger or equal to the primary beamwidth. A comparison with standard nonlinear mosaicking shows that both processing schemes are not mathematically equivalent, though they both recover the sky brightness. In particular, the weighting scheme is very different in both methods. Moreover, the proposed scheme naturally processes the short spacings from both single-dish antennas and heterogeneous arrays. Finally, the sky gridding of the measured visibilities, required by the proposed scheme, may potentially save large amounts of hard-disk space and cpu processing power over mosaicking when handling data sets acquired with the on-the-fly observing mode. Conclusions: We propose to call this promising family of imaging methods wide-field synthesis because it explicitly synthesizes visibilities at a much finer spatial frequency resolution than the one set by the diameter of the interferometer antennas.

Pety, J.; Rodríguez-Fernández, N.

2010-07-01

85

THE SPITZER DEEP, WIDE-FIELD SURVEY  

SciTech Connect

The Spitzer Deep, Wide-Field Survey (SDWFS) is a four-epoch infrared survey of 10 deg.{sup 2} in the Booetes field of the NOAO Deep Wide-Field Survey using the IRAC instrument on the Spitzer Space Telescope. SDWFS, a Spitzer Cycle 4 Legacy project, occupies a unique position in the area-depth survey space defined by other Spitzer surveys. The four epochs that make up SDWFS permit-for the first time-the selection of infrared-variable and high proper motion objects over a wide field on timescales of years. Because of its large survey volume, SDWFS is sensitive to galaxies out to z {approx} 3 with relatively little impact from cosmic variance for all but the richest systems. The SDWFS data sets will thus be especially useful for characterizing galaxy evolution beyond z {approx} 1.5. This paper explains the SDWFS observing strategy and data processing, presents the SDWFS mosaics and source catalogs, and discusses some early scientific findings. The publicly released, full-depth catalogs contain 6.78, 5.23, 1.20, and 0.96 x 10{sup 5} distinct sources detected to the average 5{sigma}, 4''-diameter, aperture-corrected limits of 19.77, 18.83, 16.50, and 15.82 Vega mag at 3.6, 4.5, 5.8, and 8.0 {mu}m, respectively. The SDWFS number counts and color-color distribution are consistent with other, earlier Spitzer surveys. At the 6 minute integration time of the SDWFS IRAC imaging, >50% of isolated Faint Images of the Radio Sky at Twenty cm radio sources and >80% of on-axis XBooetes sources are detected out to 8.0 {mu}m. Finally, we present the four highest proper motion IRAC-selected sources identified from the multi-epoch imaging, two of which are likely field brown dwarfs of mid-T spectral class.

Ashby, M. L. N.; Brodwin, M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Stern, D.; Griffith, R.; Eisenhardt, P.; Gorjian, V. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Kozlowski, S.; Kochanek, C. S. [Department of Astronomy, The Ohio State University, Columbus, OH 43210 (United States); Bock, J. J.; Borys, C. [California Institute of Technology, Pasadena, CA 91125 (United States); Brand, K.; Grogin, N. A. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Brown, M. J. I. [School of Physics, Monash University, Clayton 3800, Victoria (Australia); Cool, R. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Cooray, A. [University of California, Irvine, CA 92697 (United States); Croft, S. [University of California, Berkeley, CA 94720 (United States); Dey, A. [NOAO, 950 N. Cherry Ave., Tucson, AZ 85719 (United States); Eisenstein, D. [Steward Observatory, Tucson, AZ 85721 (United States); Gonzalez, A. H. [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Ivison, R. J. [UK Astronomy Technology Centre, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)], E-mail: mashby@cfa.harvard.edu (and others)

2009-08-10

86

Wide Field Camera 3 Accommodations for HST Robotics Servicing Mission  

NASA Technical Reports Server (NTRS)

This slide presentation discusses the objectives of the Hubble Space Telescope (HST) Robotics Servicing and Deorbit Mission (HRSDM), reviews the Wide Field Camera 3 (WFC3), and also reviews the contamination accomodations for the WFC3. The objectives of the HRSDM are (1) to provide a disposal capability at the end of HST's useful life, (2) to upgrade the hardware by installing two new scientific instruments: replace the Corrective Optics Space Telescope Axial Replacement (COSTAR) with the Cosmic Origins Spectrograph (COS), and to replace the Wide Field/Planetary Camera-2 (WFPC2) with Wide Field Camera-3, and (3) Extend the Scientific life of HST for a minimum of 5 years after servicing. Included are slides showing the Hubble Robotic Vehicle (HRV) and slides describing what the HRV contains. There are also slides describing the WFC3. One of the mechanisms of the WFC3 is to serve partially as replacement gyroscopes for HST. There are also slides that discuss the contamination requirements for the Rate Sensor Units (RSUs), that are part of the Rate Gyroscope Assembly on the WFC3.

Ginyard, Amani

2005-01-01

87

Wide field instrument preliminary design for the Wide Field InfraRed Survey Telescope  

NASA Astrophysics Data System (ADS)

We present the Wide Field Infra-Red Survey Telescope (WFIRST) wide field instrument concept based on the reuse of a 2.4m telescope recently made available to NASA. Two instrument channels are described, a wide field channel ( 0.8x0.4degrees, 300Mpix, imaging and spectroscopy over 0.76-2.0um), and an integral field unit (3x3 arcsec, 1Mpix, R{2pixel} 100 over 0.6-2.0um). For this mission concept, the telescope, instruments, and spacecraft are in a geosynchronous orbit and are designed for serviceability. This instrument can accomplish not only the baseline exoplanet microlensing, dark energy, and infrared surveys for WFIRST, but can perform at higher angular resolution and with deeper observations. This enables significant opportunities for more capable general observer programs. The emphasis on achieving very good imaging stability is maintained from the previous work.

Content, David A.; Armani, Nerses V.; Baker, Charles L.; Jackson, Clifton E.; Kahle, Duncan M.; Kruk, Jeffrey W.; Lehan, John P.; Melton, Mark E.; Mentzell, Eric; Miko, Joseph J.; Palace, David J.; Pasquale, Bert A.; Peabody, Hume L.; Smith, Brian S.; Smith, Walter F.; Stewart, Jeffrey W.; Vaughnn, David A.; Waczynski, Augustyn; Wallace, Thomas E.

2013-09-01

88

PSF modelling for very wide-field CCD astronomy  

NASA Astrophysics Data System (ADS)

Context. One of the possible approaches to detecting optical counterparts of GRBs requires monitoring large parts of the sky. This idea has gained some instrumental support in recent years, such as with the "Pi of the Sky" project. The broad sky coverage of the "Pi of the Sky" apparatus results from using cameras with wide-angle lenses (20° × 20° field of view). Optics of this kind introduce significant deformations of the point spread function (PSF), increasing with the distance from the frame centre. A deformed PSF results in additional uncertainties in data analysis. Aims: Our aim was to create a model describing highly deformed PSF in optical astronomy, allowing uncertainties caused by image deformations to be reduced. Methods: Detailed laboratory measurements of PSF, pixel sensitivity, and pixel response functions were performed. These data were used to create an effective high quality polynomial model of the PSF. Finally, tuning the model and tests in applications to the real sky data were performed. Results: We have developed a PSF model that accurately describes even very deformed stars in our wide-field experiment. The model is suitable for use in any other experiment with similar image deformation, with a simple tuning of its parameters. Applying this model to astrometric procedures results in a significant improvement over standard methods, while basic photometry precision performed with the model is comparable to the results of an optimised aperture algorithm. Additionally, the model was used to search for a weak signal - namely a possible gamma ray burst optical precursor - showing very promising results. Conclusions: Precise modelling of the PSF function significantly improves the astrometric precision and enhances the discovery potential of a wide-field system with lens optics.

Piotrowski, L. W.; Batsch, T.; Czyrkowski, H.; Cwiok, M.; Dabrowski, R.; Kasprowicz, G.; Majcher, A.; Majczyna, A.; Malek, K.; Mankiewicz, L.; Nawrocki, K.; Opiela, R.; Siudek, M.; Sokolowski, M.; Wawrzaszek, R.; Wrochna, G.; Zaremba, M.; ?arnecki, A. F.

2013-03-01

89

SPP tomography: a simple wide-field nanoscope.  

PubMed

We explore the wide-field optical nanoimaging capabilities of the surface plasmon polariton (SPP) tomography technique. We show that nanofeatures with lateral dimensions smaller than ?/20 can be observed in the surface emission (SE) images of plasmonic crystals with a period of 300 nm. Moreover, as a proof-of-concept, we demonstrate that SPP tomography permits to resolve two single objects with a center-to-center separation of 200 nm and edge-to-edge separation as small as ?/7. We present a comprehensive discussion about the nanoimaging capabilities of the SPP tomography technique. In contrast to other optical subwavelength resolution techniques, in our approach for imaging nanosize features, enhanced evanescent waves are coupled to the far-field via leakage radiation associated with SPPs excited by near-field fluorescence; therefore wide-field images, which are not out-of-plane diffraction-limited, are formed directly in the microscope's camera. We also discuss additional imaging processing capabilities associated with the fact that SPP tomography SE images are formed by the microscope lenses through an analog tomography process. PMID:23026939

Grave de Peralta, L; Regan, C J; Bernussi, A A

2013-01-01

90

Metrology systems of Hobby-Eberly Telescope wide field upgrade  

NASA Astrophysics Data System (ADS)

The Hobby-Eberly Telescope (HET) Wide-Field Upgrade (WFU) will be equipped with new closed-loop metrology systems to actively control the optical alignment of the new four-mirror Wide-Field Corrector (WFC) as it tracks sidereal motion with respect to the fixed primary mirror. These systems include a tip/tilt camera (TTCam), distance measuring interferometers (DMI), guide probes (GP), and wavefront sensors (WFS). While the TTCam and DMIs are to monitor the mechanical alignment of the WFC, the WFSs and GPs will produce direct measurement of the optical alignment of the WFC with respect to the HET primary mirror. Together, these systems provide fully redundant alignment and pointing information for the telescope, thereby keeping the WFC in focus and suppressing alignment driven field aberrations. In addition to these closed-loop metrology systems, we will have a pupil viewing camera (PVCam) and a calibration wavefront sensor (CWFS). The PVCam will be used for occasional reflectance measurement of the HET primary mirror segments in the standard R,G,B colors. The CWFS will provide the reference wavefront signal against which the other two WFS are calibrated. We describe the current snapshot of these systems and discuss lab/on-sky performance test results of the systems.

Lee, Hanshin; Hill, Gary J.; Cornell, Mark E.; Vattiat, Brian L.; Perry, Dave M.; Rafferty, Tom H.; Taylor, Trey; Hart, Michael; Rafal, Marc D.; Savage, Richard D.

2012-09-01

91

Wide-field, high-resolution Fourier ptychographic microscopy  

NASA Astrophysics Data System (ADS)

We report an imaging method, termed Fourier ptychographic microscopy (FPM), which iteratively stitches together a number of variably illuminated, low-resolution intensity images in Fourier space to produce a wide-field, high-resolution complex sample image. By adopting a wavefront correction strategy, the FPM method can also correct for aberrations and digitally extend a microscope's depth of focus beyond the physical limitations of its optics. As a demonstration, we built a microscope prototype with a resolution of 0.78 µm, a field of view of ~120 mm2 and a resolution-invariant depth of focus of 0.3 mm (characterized at 632 nm). Gigapixel colour images of histology slides verify successful FPM operation. The reported imaging procedure transforms the general challenge of high-throughput, high-resolution microscopy from one that is coupled to the physical limitations of the system's optics to one that is solvable through computation.

Zheng, Guoan; Horstmeyer, Roarke; Yang, Changhuei

2013-09-01

92

The LOFT wide field monitor simulator  

NASA Astrophysics Data System (ADS)

We present the simulator we developed for the Wide Field Monitor (WFM) aboard the Large Observatory For Xray Timing (LOFT) mission, one of the four ESA M3 candidate missions considered for launch in the 2022-2024 timeframe. The WFM is designed to cover a large FoV in the same bandpass as the Large Area Detector (LAD, almost 50% of its accessible sky in the energy range 2-50 keV), in order to trigger follow-up observations with the LAD for the most interesting sources. Moreover, its design would allow to detect transient events with fluxes down to a few mCrab in 1-day exposure, for which good spectral and timing resolution would be also available (about 300 eV FWHM and 10 ?s, respectively). In order to investigate possible WFM configurations satisfying these scientific requirements and assess the instrument performance, an end-to-end WFM simulator has been developed. We can reproduce a typical astrophysical observation, taking into account both mask and detector physical properties. We will discuss the WFM simulator architecture and the derived instrumental response.

Donnarumma, Immacolata; Evangelista, Yuri; Campana, Riccardo; In't Zand, Jean; Feroci, Marco; Lund, Niels; Brandt, Søren; Wilms, Jörn; Schmid, Christian

2012-09-01

93

Wide field camera observations of Baade's Window  

NASA Technical Reports Server (NTRS)

We have observed a field in Baade's Window using the Wide Field Camera (WFC) of the Hubble Space Telescope (HST) and obtain V- and I-band photometry down to V approximately 22.5. These data go several magnitudes fainter than previously obtained from the ground. The location of the break in the luminosity function suggests that there are a significant number of intermediate age (less than 10 Gyr) stars in the Galactic bulge. This conclusion rests on the assumptions that the extinction towards our field is similar to that seen in other parts of Baade's Window, that the distance to the bulge is approximately 8 kpc, and that we can determine fairly accurate zero points for the HST photometry. Changes in any one of these assumptions could increase the inferred age, but a conspiracy of lower reddening, a shorter distance to the bulge, and/or photometric zero-point errors would be needed to imply a population entirely older than 10 Gyr. We infer an initial mass function slope for the main-sequence stars, and find that it is consistent with that measured in the solar neighborhood; unfortunately, the slope is poorly constrained because we sample only a narrow range of stellar mass and because of uncertainties in the observed luminosity function at the faint end.

Holtzman, Jon A.; Light, R. M.; Baum, William A.; Worthey, Guy; Faber, S. M.; Hunter, Deidre A.; O'Neil, Earl J., Jr.; Kreidl, Tobias J.; Groth, E. J.; Westphal, James A.

1993-01-01

94

Optical MEMS: past, present and future  

NASA Astrophysics Data System (ADS)

Spurred by the growth of the internet, Optical Telecommunications bandwidth, experienced unprecedented growth during late 1990's. During this time of great economic expansion, the creation of new enterprises was vast and the expansion of established component, system and services companies was breathtaking. Unfortunately, this positive economic state was short-lived. This period was followed in 2001-2004 by one of the most significant market crashes in history. During those 10 years of economic growth, about $20B in venture capital was invested in the optical telecom industry, most of this investment was lost in recent years. Many start-up industries which experienced unprecedented growth at the end of the 20th century were lost at the start of the 21st. (1) During this time many, innovative technologies were born and buried. However, many new capabilities emerged from this period of unrest; one such example is the advent of Optical MEMS (MOEMS). Many academics and corporate laboratories pursued the development of MOEMS during the economic boom and, in the author's view; MOEMS surfaced as a powerful and versatile tool set that has proved invaluable and in the last few years during economic downturn, stood the test of time. In the Telecommunications industry, for optical switching and wavelength management applications MOEMS has proven to be the technology of choice. (2) Variable Optical Attenuators (VOA), Wavelength Blockers (WB), Dynamic Gain Equalizers (DGE), and most recently Wavelength Selective Switches (WSS) are being used in the numerous recent network deployments. Moreover, agile networks of the future will have MOEMS at every node. This presentation will provide an overview of the history of MOEMS in Telecommunications, discuss its byproducts and offer a window into the future of the technology.

Ramani, Chandra Mouli

2005-09-01

95

Facility calibration unit of Hobby Eberly Telescope wide field upgrade  

NASA Astrophysics Data System (ADS)

The Hobby-Eberly Telescope (HET) Wide-Field Upgrade (WFU) will be equipped with new Facility Calibration Unit (FCU). The FCU is in support of VIRUS and the facility instruments and consists of the head and source box. The FCU head, connected to the source box through two liquid light guides, is attached to the bottom of the WFU Wide-Field Corrector (WFC) and can be deployed into the beam to inject calibration light through the WFC whenever calibration is needed. A set of Fresnel lenses is used in the FCU head to mimic the caustics of M1 as much as possible to re-produce the telescope’s focal plane illumination pattern. Various imaging/non-imaging optical components (e.g. Compound Parabolic Concentrators, cone reflectors, condenser lenses) are used for efficient coupling between different types of calibration lamps and light guides, covering wavelengths from 350nm to 1800nm. In addition, we developed an efficient and tunable Light-Emitting Diode (LED) based source and coupler for UV and Visible spectral flat field calibration. This paper presents the designs, prototypes, and as-built components / subsystems of the FCU.

Lee, Hanshin; Hill, Gary J.; Vattiat, Brian L.; Smith, Michael P.; Haeuser, Marco

2012-09-01

96

The wide field upgrade for the Hobby-Eberly Telescope  

NASA Astrophysics Data System (ADS)

A major performance upgrade for the Hobby-Eberly Telescope (HET) is in the conceptual design phase. The extensive upgrade will include a wide field optical corrector, a new HET tracker with increased payload capacity, and improved telescope pointing and tracking accuracy. The improvements will support the HET Dark Energy Experiment (HETDEX), which seeks to characterize the evolution of dark energy by mapping the imprint of baryonic oscillations on the large scale structure of the Universe. HETDEX will use the increased field-of-view and payload to feed an array of approximately 145 fiber-fed spectrometers, called VIRUS for "Visible Integral field Replicable Unit Spectrograph". The new corrector will have a science field-of-view diameter of 18 arcminutes, in contrast to the original corrector's 4 arcminute field, a twenty-fold increase in area. A new HET tracker with increased payload capacity will be designed to support the wide field corrector. Improved pointing and tracking will be accomplished using new autocollimation and distance measuring metrology combined with real-time wavefront sensing and correction. The upgrade will maintain operation of the current suite of facility instruments, consisting of low, medium, and high resolution spectrometers.

Booth, John A.; MacQueen, Phillip J.; Good, John M.; Wesley, Gordon L.; Hill, Gary J.; Palunas, Povilas; Segura, Pedro R.; Calder, Robert E.

2006-07-01

97

OAOWFC: Okayama Astrophysical Observatory NIR Wide-Field Camera  

SciTech Connect

In order to detect and trace the early phase of near-infrared (NIR) afterglows of Gamma Ray Bursts (GRBs) quickly, we are now developing the Okayama Astrophysical Observatory Wide-Field Camera, OAOWFC. The aperture size of OAOWFC is 91 cm. The focal plane is covered by a 2Kx2K HAWAII2-RG detector with a pixel size of 18.5 {mu}mx18.5 {mu}m, resulting 0.95x0.95 deg{sup 2} field of view with an image scale of 1.6 arcsec/pixel. OAOWFC is designed to be a fully robotic instrument. This camera forms a part of Multicolor Imaging Telescopes for Survey and Monstrous Explosions (MITSuME), a multi telescope system dedicated to optical-NIR follow-up observations of GRB afterglows. Very wide field of view of OAOWFC enables us to catch GRB afterglows under less accurate localization sometimes given by the first alert. OAOWFC has an ability to detect bright GRB afterglow located at z = 10 easily, and it might be detectable at z = 18 if the conditions are met.

Yoshida, M.; Yanagisawa, K.; Shimizu, Y.; Okita, K.; Nagayama, S.; Toda, H. [Okayama Astrophysical Observatory, Kamogata, Okayama 719-0232 (Japan); Ohta, K. [Department of Astronomy Kyoto University, Kyoto 606-8502 (Japan); Kawai, N. [Department of Physics, Tokyo Institute of Technology, Meguro-ku, Tokyo 152-8551 (Japan)

2008-05-22

98

Optical coherence tomography - current and future applications  

PubMed Central

Purpose of review Optical coherence tomography (OCT) has revolutionized the clinical practice of ophthalmology. It is a noninvasive imaging technique that provides high-resolution, cross-sectional images of the retina, retinal nerve fiber layer and the optic nerve head. This review discusses the present applications of the commercially available spectral-domain OCT (SD-OCT) systems in the diagnosis and management of retinal diseases, with particular emphasis on choroidal imaging. Future directions of OCT technology and their potential clinical uses are discussed. Recent findings Analysis of the choroidal thickness in healthy eyes and disease states such as age-related macular degeneration, central serous chorioretinopathy, diabetic retinopathy and inherited retinal dystrophies has been successfully achieved using SD-OCT devices with software improvements. Future OCT innovations such as longer-wavelength OCT systems including the swept-source technology, along with Doppler OCT and en-face imaging, may improve the detection of subtle microstructural changes in chorioretinal diseases by improving imaging of the choroid. Summary Advances in OCT technology provide for better understanding of pathogenesis, improved monitoring of progression and assistance in quantifying response to treatment modalities in diseases of the posterior segment of the eye. Further improvements in both hardware and software technologies should further advance the clinician’s ability to assess and manage chorioretinal diseases.

Adhi, Mehreen; Duker, Jay S.

2013-01-01

99

Wide-field surveys from the SNAP mission  

SciTech Connect

The Supernova/Acceleration Probe (SNAP) is a proposed space-borne observatory that will survey the sky with a wide-field optical/NIR imager. The images produced by SNAP will have an unprecedented combination of depth, solid-angle, angular resolution, and temporal sampling. Two 7.5 square-degree fields will be observed every four days over 16 months to a magnitude depth of AB = 27.7 in each of nine filters. Co-adding images over all epochs will give an AB = 30.3 per filter. A 300 square-degree field will be surveyed with no repeat visits to AB = 28 per filter. The nine filters span 3500-17000 {angstrom}. Although the survey strategy is tailored for supernova and weak gravitational lensing observations, the resulting data supports a broad range of auxiliary science programs.

agkim@lbl.gov

2002-07-23

100

Thermal design of the Wide Field/Planetary Camera  

NASA Technical Reports Server (NTRS)

The Wide Field/Planetary Camera is an imaging system developed by the Jet Propulsion Laboratory for the NASA Hubble Space Telescope currently scheduled to be launched in December 1989 aboard the space shuttle. The temperature control design of the instrument utilizes multilayered insulation, electric resistance heaters, aluminum/ammonia heat pipes, thermoelectric coolers, temperature control coatings, and space radiators. A feedback control system maintains stable sensor temperatures. Thermal capacitance maintains stable optics and electronics temperatures during transient conditions. Schedule slips and launch delays have allowed extensive thermal testing of the instrument. Six instrument thermal vacuum tests and a spacecraft thermal vacuum test were performed. Several modifications have been made to the instrument to correct icing and contamination problems that have been discovered during thermal vacuum testing. This paper describes the thermal design, last instrument thermal vacuum test, results, and thermal model correlation.

Garcia, R. D.; Jones, J. A.; Stultz, J. W.

1989-01-01

101

Virtualized Optical Network (VON) for Future Internet and Applications  

NASA Astrophysics Data System (ADS)

A virtualized optical network (VON) is proposed as a key to implementing increased agility and flexibility into the future Internet and applications by providing any-to-any connectivity with the appropriate optical bandwidth at the appropriate time. The VON is enabled by introducing optical transparentization and optical fine granular grooming based on optical orthogonal frequency division multiplexing.

Jinno, Masahiko; Tsukishima, Yukio; Takara, Hidehiko; Kozicki, Bartlomiej; Sone, Yoshiaki; Sakano, Toshikazu

102

A Concentric Wide Field Lens Design.  

National Technical Information Service (NTIS)

The line scan television satellite required an optical system covering a very wide angle of 85 degrees by only 3 degrees and with equally high resolution extending out to the edge of the field. The requirement prompted a design study that resulted in the ...

R. G. Hires

1968-01-01

103

WFIS: a wide field-of-view imaging spectrometer  

NASA Astrophysics Data System (ADS)

This paper presents the design and initial test results of the laboratory Wide Field-of-View Imaging Spectrometer (WFIS). The WFIS is a patented optical design intended for use in remote sensing of the Earth and the Earth's atmosphere in the hyperspectral imaging mode. It is meant to operate as a pushbroom imager to provide coverage of the Earth from low Earth orbit without scanning mechanisms. The optical system occupies a volume measuring less than 20 cm X 18 cm X 13 cm. The laboratory unit covers the 500 nm to 1000 nm wavelength range over a cross-track field of view of 70 degrees. The image is focused onto a CCD area array such that the spatial component falls along the horizontal direction and the spectral information is dispersed along the vertical direction. The system's focal length is 7.5 mm with an effective focal ratio of 3.7. A holographic grating produced on a unique convex substrate is the dispersing element. A key feature of the WFIS is an all-reflective optical path, allowing the basic design to be adapted to wavelength regions from the UV to the IR. Presented are the initial test results of the laboratory spectrometer that characterize its spatial and spectral performance over a 70 degree X 0.08 degree field of view.

Haring, Robert E.; Williams, Frederick L.; Vanstone, Gary C.; Putnam, Gloria G.

1999-12-01

104

Future for security applications of optical holography  

NASA Astrophysics Data System (ADS)

The use of holograms for security and authentication accounts for around half of all optical holograms produced. This sector is crucial to the hologram industry. Yet it is under threat, as holograms become the target of criminals around the world who wish to counterfeit the documents and products the holograms protect. It is possible to produce holograms using techniques and security procedures which raise the barriers to the counterfeiters, but the hologram industry appears to be complacent and inadequately prepared to deal with this threat to its future. This requires the production of appropriate holograms for each application, awareness, education, and policing. A suitable vehicle for the implementation of these tasks now exists in the International Hologram Manufacturers Association and its Hologram Image Register.

Lancaster, Ian M.

1995-07-01

105

The photometric system of the Nanshan One-meter Wide field Telescope  

NASA Astrophysics Data System (ADS)

A one-meter wide field astronomical telescope with Alt-Az mount, putting in work at prime focus with field corrector, is located at the Nanshan site of Xinjiang Astronomical Observatory. The Nanshan One meter Wide-field Telescope (hereafter NOWT) provides excellent optical quality, pointing accuracy and tracking accuracy. The main scientific goals of NOWT are supernovae, gamma-ray bursts, novae, variable stars, and active galactic nuclei. It is worthwhile to point out that the sky background at the Nanshan is a classic optical site.

Liu, Jinzhong; Zhang, Yu; Feng, Guojie; Bai, Chunhai

2014-01-01

106

The Wide-Field Imaging Interferometry Testbed (WIIT): Recent Progress and Results  

NASA Technical Reports Server (NTRS)

Continued research with the Wide-Field Imaging Interferometry Testbed (WIIT) has achieved several important milestones. We have moved WIIT into the Advanced Interferometry and Metrology (AIM) Laboratory at Goddard, and have characterized the testbed in this well-controlled environment. The system is now completely automated and we are in the process of acquiring large data sets for analysis. In this paper, we discuss these new developments and outline our future research directions. The WIIT testbed, combined with new data analysis techniques and algorithms, provides a demonstration of the technique of wide-field interferometric imaging, a powerful tool for future space-borne interferometers.

Rinehart, Stephen A.; Frey, Bradley J.; Leisawitz, David T.; Lyon, Richard G.; Maher, Stephen F.; Martino, Anthony J.

2008-01-01

107

The Wide-Field Imaging Interferometry Testbed: Progress and Plans  

NASA Technical Reports Server (NTRS)

We describe the technique of wide field mosaic imaging for optical/IR interferometers and present early experimental results from a laboratory instrument designed to validate, experiment with, and refine the technique. A conventional single-detector stellar interferometer operating with narrow bandwidth at center wavelength lambda is limited in its field of view to the primary beam of the individual telescope apertures, or approx. lambda/D(sub tel) radians, where is the telescope diameter. Such a field is too small for many applications; often one wishes to image extended sources. We are developing and testing a technique analogous to the mosaic method employed in millimeter and radio astronomy, but applicable to optical/IR Michelson interferometers, in which beam combination is done in the pupil plane. An N(sub pix) x N(sub pix) detector array placed in the image plane of the interferometer is used to record simultaneously the fringe patterns from many contiguous telescope fields, effectively multiplying the field size by N(sub pix)/2, where the factor 2 allows for Nyquist sampling. This mosaic imaging technique will be especially valuable for far IR and submillimeter interferometric space observatories such as the Space Infrared Interferometric Telescope (SPIRIT) and the Submillimeter Probe of the Evolution of Cosmic Structure (SPECS). SPIRIT and SPECS will be designed to provide sensitive, high angular resolution observations of fields several arcminutes in diameter, and views of the universe complementary to those provided by HST, NGST, and ALMA.

Rinehart, S. A.; Leisawitz, D.; Leviton, D.; Martino, A.; Maynard, W.; Mundy, L. G.; Zhang, X.

2004-01-01

108

Wide-Field Image Compensation with Multiple Laser Guide Stars  

NASA Astrophysics Data System (ADS)

We report closed-loop results obtained from an adaptive optics system with multiple laser guide beacons. The system is mounted on the 6.5 m MMT telescope in Arizona, and is designed to explore advanced altitude-conjugated techniques for wide-field image compensation. Five beacons are made by Rayleigh scattering of laser beams at 532 nm integrated over a range from 20 to 29 km by dynamic refocus of the telescope optics. The return light is analyzed by a unique Shack-Hartmann sensor that places all five beacons on a single detector, with electronic shuttering to implement the beacon range gate. The wavefront sensor divides the 6.5 m telescope pupil into 60 subapertures, and wavefront correction is applied with the telescope's unique deformable secondary mirror. The system has now begun operations as a tool for astronomical science, in a mode in which the boundary-layer turbulence, close to the telescope, is compensated. Image quality of 0.2-0.3 arcsec is routinely delivered in the near infrared bands from 1.2 to 2.5 microns over a field of view of 2 arcmin. Although it does not reach the diffraction limit, this represents a 3 to 4-fold improvement in resolution over the natural seeing, and a field of view an order of magnitude larger than conventional adaptive optics systems deliver. In this paper we present performance metrics including images of the core of a globular cluster where correction is almost uniform across the full field, and preliminary results from the first scientific program to take advantage of the system.

Hart, M.; Milton, N.; Powell, K.; Baranec, C.; Stalcup, T.; McCarthy, D.; Kulesa, C.

109

Wide-field fluorescent microscopy on a cell-phone.  

PubMed

We demonstrate wide-field fluorescent imaging on a cell-phone, using compact and cost-effective optical components that are mechanically attached to the existing camera unit of the cell-phone. Battery powered light-emitting diodes (LEDs) are used to side-pump the sample of interest using butt-coupling. The pump light is guided within the sample cuvette to excite the specimen uniformly. The fluorescent emission from the sample is then imaged with an additional lens that is put in front of the existing lens of the cell-phone camera. Because the excitation occurs through guided waves that propagate perpendicular to the detection path, an inexpensive plastic color filter is sufficient to create the dark-field background needed for fluorescent imaging. The imaging performance of this light-weight platform (~28 grams) is characterized with red and green fluorescent microbeads, achieving an imaging field-of-view of ~81 mm(2) and a spatial resolution of ~10 ?m, which is enhanced through digital processing of the captured cell-phone images using compressive sampling based sparse signal recovery. We demonstrate the performance of this cell-phone fluorescent microscope by imaging labeled white-blood cells separated from whole blood samples as well as water-borne pathogenic protozoan parasites such as Giardia Lamblia cysts. PMID:22255900

Zhu, Hongying; Yaglidere, Oguzhan; Su, Ting-Wei; Tseng, Derek; Ozcan, Aydogan

2011-01-01

110

Non-mydriatic, wide field, fundus video camera  

NASA Astrophysics Data System (ADS)

We describe a method we call "stripe field imaging" that is capable of capturing wide field color fundus videos and images of the human eye at pupil sizes of 2mm. This means that it can be used with a non-dilated pupil even with bright ambient light. We realized a mobile demonstrator to prove the method and we could acquire color fundus videos of subjects successfully. We designed the demonstrator as a low-cost device consisting of mass market components to show that there is no major additional technical outlay to realize the improvements we propose. The technical core idea of our method is breaking the rotational symmetry in the optical design that is given in many conventional fundus cameras. By this measure we could extend the possible field of view (FOV) at a pupil size of 2mm from a circular field with 20° in diameter to a square field with 68° by 18° in size. We acquired a fundus video while the subject was slightly touching and releasing the lid. The resulting video showed changes at vessels in the region of the papilla and a change of the paleness of the papilla.

Hoeher, Bernhard; Voigtmann, Peter; Michelson, Georg; Schmauss, Bernhard

2014-02-01

111

Focus Validation of the Wide-Field Infrared Explorer (WIRE)  

NASA Astrophysics Data System (ADS)

The Wide-Field Infrared Explorer (WIRE) is a small cryogenic spaceborne infrared telescope being readied for launch in September 1998 as the fifth of NASA's Small Explorers. WIRE illuminates two 128 x 128 Si:As Focal Plane Arrays (FPAs) produced by Boeing North American with a 30 cm diameter Ritchey Cretien diamond turned mirror system. A dichroic beam splitter and band-pass filter define two broad pass bands for a deep pointed survey to search for protogalaxies and to study the evolution of starburst galaxies. The Space Dynamics Laboratory at Utah State University (SDL/USU) developed and instrumented ground-based procedures to validate the focus of the WIRE Instrument. The procedures used point source data acquired during ground measurements obtained with a calibration source consisting of an illuminated pinhole near the focus of a cryogenically cooled collimator. Simulated point source measurements were obtained at multiple focus positions by translating the pinhole along the optical axis inside and outside the optimum focus of the collimator. The detector FPAs were moved to positions indicated by the test results. These focus positions were verified by subsequent cold tests using an independent cold collimator. The method and hardware used to obtain focus validation are described and results presented.

Tansock, J.; Larsen, M.; Shumway, A.; Hacking, P.

1998-09-01

112

Wide Field InfraRed Survey Telescope (WFIRST) Science Yield  

NASA Astrophysics Data System (ADS)

The Wide-Field Infrared Survey Telescope mission (WFIRST) is the Decadal Survey's highest recommended space mission. Its three mandates are (1) to study dark energy via measurement of the expansion history of the universe and the growth of large-scale structure, thereby providing tight constraints on the equation of state of dark energy and test the validity of general relativity; (2) to conduct intensive imaging of selected regions for exoplanet microlensing; and (3) to provide a general purpose surveying capability for the near infrared waveband. During the coming year, a Science Definition Team will be empaneled to prioritize the mission payload features and operations plans. To begin the misson definition process, we present four alternative WFIRST concepts and compare their quantitative science yields based on survey rates. We contrast these with alternative missions that have been proposed previously. Our WFIRST calculations are based on a newly developed unobscured focal TMA optical concept offering distinct simultaneous focal lengths for imaging and spectroscopy, reported in a companion poster by Sholl et al, and on a large modular focal plane concept reported on on a companion poster by Jelinsky et al. With these advances, we show that WFIRST can deliver a science yield superior to previously discussed dark energy and exoplanet missions.

Levi, Michael; Lampton, M.; Sholl, M.

2011-01-01

113

Design of wide field and high resolution video lens  

NASA Astrophysics Data System (ADS)

Online detecting is increasingly used in industrial process for the requirement of product quality improving. It is a trend that the "machine detecting" with "machine version + computer intelligence" as new method replaces traditional manual "eye observation". The essential of "machine detecting" is that image of object being collected with high resolution video lens on sensor panel of photoelectric (CCD ,CMOS) and detecting result being automatically gained by computer after the image saved and processed. "Machine detecting" is developing rapidly with the universal reception by enterprises because of its fine accurateness, high efficiency and the real time. Video lens is one of the important components of machine version system. Requirements of wide field and high resolution enlarged the complexity of video lens design. In this paper a design case used in visible light with field diameter ?32mm, ?=-0.25× and NA'=0.15. We give design parameters of the video lens which obtained with theoretically calculating and Oslo software optimization: MTF>0.3 in full field and 215lp/mm, distortion <0.05%.This lens has an excellent optic performance to match with 1.3 million pixels 1/2"CCD, and a high performance price ratio for being consist of only 7 single lens in the way of 5 units.

Xiao, Ze-Xin; Zhan, Binzhou; Han, Haimei

2009-11-01

114

Optical services in future broadband networks  

Microsoft Academic Search

Optical transmission technology is progressing to the point where it can deliver data at rates that can strain conventional electronic broadband networks. We discuss how optical networks may play a role in relieving this strain. Different optical network architectures are discussed according to the services they provide, the technologies used to implement those services, and the geographical size of the

Steven G. Finn; R. A. Barry

1996-01-01

115

A wide-field telescope with spherical optics  

NASA Technical Reports Server (NTRS)

Utilizing a doublet lens to correct the aberrations of a spherical mirror, a small f/8 telescope for visual use was designed and constructed. The lens has considerable negative power, so that it serves as a Barlow lens as well as a corrector.

Jones, R. T.

1976-01-01

116

MEO and LEO space debris optical observations at Crimean Observatory: first experience and future perspectives.  

NASA Astrophysics Data System (ADS)

The near Earth space observation group of Crimean Observatory is performing the regular op-tical monitoring of space debris at GEO region within framework of the International Scientific Optical Network (ISON). During last years we also paid attention to objects on lower orbits due to increasing interest to LEO and MEO regions caused by several catastrophic events happened in the recent past. Optical observations provide high quality information about position and physical properties of space debris at LEO and MEO so they can be considered as another source of data comple-mentary to traditional radar measurements. We will discuss our observations of fragments from Briz-M upper stage (object 28944) and Block-DM ullage motor (25054) explosions. Results of observation of USA-193 debris will be presented. Then we will focus on observations and some photometric properties of FengYun 1C debris as well as Cosmos 2251 and Iridium 33 fragments. Radar cross-section versus optical photometry will be compared. Moreover, estimates of orbital parameters as well as area-to-mass ratio for some observed objects will be given. Most of our observations which we discuss in the paper represent just the first attempt to investigate capabilities of our optical system to observe MEO and LEO objects. But these results are very promising and show good perspectives for the future. We will briefly describe future perspectives of our optical observations of space debris and other objects in MEO and LEO region after the new wide-field telescopes will be put into operation.

Rumyantsev, Vasilij; Biryukov, Vadim; Agapov, Vladimir; Molotov, Igor

117

The Spitzer Deep, Wide-Field Survey (SDWFS)  

Microsoft Academic Search

The Spitzer Deep, Wide-Field Survey (SDWFS) is four-epoch infrared survey of ten square degrees in the Bootes field of the NOAO Deep Wide-Field Survey using the IRAC instrument on the Spitzer Space Telescope. The four epochs, which span the interval from 2003 to 2008, make it possible to identify nearby, high-proper-motion targets, as well as infrared-variable objects. SDWFS is a

Matthew Ashby; D. Stern; M. Brodwin; R. Griffith; P. Eisenhardt; S. Kozlowski; C. S. Kochanek; J. Bock; C. Borys; K. Brand; M. J. I. Brown; R. Cool; A. Cooray; S. Croft; A. Dey; D. Eisenstein; A. Gonzalez; V. Gorjian; N. Grogin; R. Ivison; J. Jacob; B. Jannuzi; A. Mainzer; L. Moustakas; H. Rottgering; N. Seymour; H. Smith; A. Stanford; J. R. Stauffer; I. Sullivan; W. van Breugel; E. L. Wright; S. P. Willner

2009-01-01

118

Metal multilayer mirrors for EUV wide field telescopes  

SciTech Connect

Metal multilayer mirrors have been designed for the ALEXIS satellite, which is to carry six wide field telescopes to perform an all-sky survey in three or four narrow wavelength bands in the EUV. Comprised of alternating layers of molybdenum and silicon, the mirrors are optimized to provide maximum reflectivity at angles from 11.5 to 17/degree/ off normal incidence and at wavelengths of 133, 171, or 186A. Simultaneously, the mirrors use a ''wavetrap'' described below to suppress reflectivity at 304A, where the extremely strong geocoronal line of He II causes severe background problems. Low reflectivity at 304A is achieved by superposing two layer pairs that provide destructive interference with an effective 2d spacing of 152A. The Mo layers in this wavetrap must be very thin, about 10A each, in order to allow the shorter wavelengths desired for peak reflectivity to penetrate without significant attenuation. Because refraction changes the effective angle of passage through the wavetrap, a joint optimization between layer thicknesses in the deep layers and the wavetrap layers must be performed for each target peak wavelength. For the 186A mirror, the optimum design from substrate upward is 40 layer pairs, each 74A Si and 31A Mo, followed by 2 layer pairs, each 55A Si and 10A Mo. Calculations predict this design will have a peak reflectivity at 186A of 35 percent and a 304A reflectivity less than 10/sup /minus/5/, if available optical constants are correct and the multilayer can be fabricated without difficulty. We will present details of the calculations and laboratory measurements of the reflectivity performance attained with prototype mirrors. 6 refs., 2 figs.

Smith, B.W.; Bloch, J.J.; Roussel-Dupre,D.

1989-01-01

119

Automated Classification of Periodic Variable Stars Detected by the Wide-field Infrared Survey Explorer  

NASA Astrophysics Data System (ADS)

We describe a methodology to classify periodic variable stars identified using photometric time-series measurements constructed from the Wide-field Infrared Survey Explorer (WISE) full-mission single-exposure Source Databases. This will assist in the future construction of a WISE Variable Source Database that assigns variables to specific science classes as constrained by the WISE observing cadence with statistically meaningful classification probabilities. We have analyzed the WISE light curves of 8273 variable stars identified in previous optical variability surveys (MACHO, GCVS, and ASAS) and show that Fourier decomposition techniques can be extended into the mid-IR to assist with their classification. Combined with other periodic light-curve features, this sample is then used to train a machine-learned classifier based on the random forest (RF) method. Consistent with previous classification studies of variable stars in general, the RF machine-learned classifier is superior to other methods in terms of accuracy, robustness against outliers, and relative immunity to features that carry little or redundant class information. For the three most common classes identified by WISE: Algols, RR Lyrae, and W Ursae Majoris type variables, we obtain classification efficiencies of 80.7%, 82.7%, and 84.5% respectively using cross-validation analyses, with 95% confidence intervals of approximately ±2%. These accuracies are achieved at purity (or reliability) levels of 88.5%, 96.2%, and 87.8% respectively, similar to that achieved in previous automated classification studies of periodic variable stars.

Masci, Frank J.; Hoffman, Douglas I.; Grillmair, Carl J.; Cutri, Roc M.

2014-07-01

120

Neutron polycapillary optics: back to future  

NASA Astrophysics Data System (ADS)

At the sunrise of the Kumakhov optics, the latter was enormously attractive for neutron scientists eager to take advantage from focused neutron beams. However, in spite of this initial enthusiasm, rear neutron applications of polycapillary optics are mostly limited either to feasibility studies or to non-scattering techniques. The reason for such a drawback is a serious degradation in the momentum resolution of neutron scattering methods caused by increased divergence of focused beams. However, limited brightness of present day neutron sources (both existing and coming) requires rethinking the current situation. Neutron lenses are successfully tested for low Q-resolution applications providing an enormous increase of neutron flux at small samples. Moreover, some recent developments in the field of neutron instrumentation allow us to overcome the resolution problem by decoupling the angular resolution and the incident beam divergence thus opening the opportunity for the use of focusing neutron optics in some high Q-resolution application. Further advances in technology required to improve the performance of neutron polycapillary optics, also in combination with modem methods of polarization of neutron beams, are discussed.

Ioffe, Alexander

2005-08-01

121

IAU Working Group on Wide-Field Imaging.  

NASA Astrophysics Data System (ADS)

Contents: 1. Introduction - The IAU Working Group on Wide-Field Imaging (R. M. West). 2. Reports from the Sub-Sections of the Working Group - a. Sky surveys and patrols (R. M. West). b. Photographic techniques (D. F. Malin). c. Digitization techniques (H. T. MacGillivray). d. Archival and retrieval of wide-field data (B. Lasker). 3. Meeting of the Organising Committee (R. M. West). 4. Wide-field plate archives (M. Tsvetkov). 5. Reproduction of the Palomar Observatory Sky Surveys (R. J. Brucato). 6. Status of the St ScI scan-distribution program (B. Lasker). 7. Pixel addition - pushing Schmidt plates to B = 25 (M. R. S. Hawkins). 8. Photometry from Estar film (S. Phillipps, Q. Parker). 9. ASCHOT - Astrophysical Schmidt Orbital Telescope (H. Lorenz). 10. The Hitchhiker parallel CCD camera (J. Davies, M. Disney, S. Driver, I. Morgan, S. Phillipps).

MacGillivray, H. T.

1991-01-01

122

Deepest Wide-Field Colour Image in the Southern Sky  

NASA Astrophysics Data System (ADS)

LA SILLA CAMERA OBSERVES CHANDRA DEEP FIELD SOUTH ESO PR Photo 02a/03 ESO PR Photo 02a/03 [Preview - JPEG: 400 x 437 pix - 95k] [Normal - JPEG: 800 x 873 pix - 904k] [HiRes - JPEG: 4000 x 4366 pix - 23.1M] Caption : PR Photo 02a/03 shows a three-colour composite image of the Chandra Deep Field South (CDF-S) , obtained with the Wide Field Imager (WFI) camera on the 2.2-m MPG/ESO telescope at the ESO La Silla Observatory (Chile). It was produced by the combination of about 450 images with a total exposure time of nearly 50 hours. The field measures 36 x 34 arcmin 2 ; North is up and East is left. Technical information is available below. The combined efforts of three European teams of astronomers, targeting the same sky field in the southern constellation Fornax (The Oven) have enabled them to construct a very deep, true-colour image - opening an exceptionally clear view towards the distant universe . The image ( PR Photo 02a/03 ) covers an area somewhat larger than the full moon. It displays more than 100,000 galaxies, several thousand stars and hundreds of quasars. It is based on images with a total exposure time of nearly 50 hours, collected under good observing conditions with the Wide Field Imager (WFI) on the MPG/ESO 2.2m telescope at the ESO La Silla Observatory (Chile) - many of them extracted from the ESO Science Data Archive . The position of this southern sky field was chosen by Riccardo Giacconi (Nobel Laureate in Physics 2002) at a time when he was Director General of ESO, together with Piero Rosati (ESO). It was selected as a sky region towards which the NASA Chandra X-ray satellite observatory , launched in July 1999, would be pointed while carrying out a very long exposure (lasting a total of 1 million seconds, or 278 hours) in order to detect the faintest possible X-ray sources. The field is now known as the Chandra Deep Field South (CDF-S) . The new WFI photo of CDF-S does not reach quite as deep as the available images of the "Hubble Deep Fields" (HDF-N in the northern and HDF-S in the southern sky, cf. e.g. ESO PR Photo 35a/98 ), but the field-of-view is about 200 times larger. The present image displays about 50 times more galaxies than the HDF images, and therefore provides a more representative view of the universe . The WFI CDF-S image will now form a most useful basis for the very extensive and systematic census of the population of distant galaxies and quasars, allowing at once a detailed study of all evolutionary stages of the universe since it was about 2 billion years old . These investigations have started and are expected to provide information about the evolution of galaxies in unprecedented detail. They will offer insights into the history of star formation and how the internal structure of galaxies changes with time and, not least, throw light on how these two evolutionary aspects are interconnected. GALAXIES IN THE WFI IMAGE ESO PR Photo 02b/03 ESO PR Photo 02b/03 [Preview - JPEG: 488 x 400 pix - 112k] [Normal - JPEG: 896 x 800 pix - 1.0M] [Full-Res - JPEG: 2591 x 2313 pix - 8.6M] Caption : PR Photo 02b/03 contains a collection of twelve subfields from the full WFI Chandra Deep Field South (WFI CDF-S), centred on (pairs or groups of) galaxies. Each of the subfields measures 2.5 x 2.5 arcmin 2 (635 x 658 pix 2 ; 1 pixel = 0.238 arcsec). North is up and East is left. Technical information is available below. The WFI CDF-S colour image - of which the full field is shown in PR Photo 02a/03 - was constructed from all available observations in the optical B- ,V- and R-bands obtained under good conditions with the Wide Field Imager (WFI) on the 2.2-m MPG/ESO telescope at the ESO La Silla Observatory (Chile), and now stored in the ESO Science Data Archive. It is the "deepest" image ever taken with this instrument. It covers a sky field measuring 36 x 34 arcmin 2 , i.e., an area somewhat larger than that of the full moon. The observations were collected during a period of nearly four years, beginning in January 1999 when the WFI instrument was first installed (cf. ESO PR 02/99

2003-01-01

123

A wide-field microscopy technique using a linear image sensor for obtaining 3D images  

Microsoft Academic Search

Three-dimensional (3D) microscopy is a huge field that includes several microscopy techniques. Among these techniques the confocal microscopy is widely known and used due to its improved axial resolution or optical sectioning ability. However its high cost and image acquisition time as well as low signal-to-noise ratio are important drawbacks. Other techniques use wide-field structured illumination to get depth information

Milton P. Macedo; Antonio J. Barata; Ana G. Fernandes; Carlos M. Correia

2005-01-01

124

PyWiFeS: Wide Field Spectrograph data reduction pipeline  

NASA Astrophysics Data System (ADS)

PyWiFeS is a Python-based data reduction pipeline for the Wide Field Spectrograph (WiFeS). Its core data processing routines are built on standard scientific Python packages commonly used in astronomical applications. It includes an implementation of a global optical model of the spectrograph which provides wavelengths solutions accurate to ˜0.05 Å (RMS) across the entire detector. Through scripting, PyWiFeS can enable batch processing of large quantities of data.

Childress, Michael; Vogt, Frédéric; Nielsen, Jon; Sharp, Rob

2014-02-01

125

The second generation Wide-Field/Planetary Camera on the Hubble Space Telescope  

NASA Technical Reports Server (NTRS)

The general design and principal features of the second generation Wide-Field/Planetary Camera (WFPC-2) for the Hubble Space Telescope are reviewed. The discussion covers the background of WFPC-2 development, science capabilities, key performance parameters, optical and electronic equipment, mechanisms, thermal control, and contamination control. Attention is also given to on-orbit operations, including commanding and telemetry and on-orbit servicing.

Leschly, Kim; Allestad, David; Herrell, Linda

1991-01-01

126

Wide-Field Imaging Interferometry Spatial-Spectral Image Synthesis Algorithms  

NASA Technical Reports Server (NTRS)

Developed is an algorithmic approach for wide field of view interferometric spatial-spectral image synthesis. The data collected from the interferometer consists of a set of double-Fourier image data cubes, one cube per baseline. These cubes are each three-dimensional consisting of arrays of two-dimensional detector counts versus delay line position. For each baseline a moving delay line allows collection of a large set of interferograms over the 2D wide field detector grid; one sampled interferogram per detector pixel per baseline. This aggregate set of interferograms, is algorithmically processed to construct a single spatial-spectral cube with angular resolution approaching the ratio of the wavelength to longest baseline. The wide field imaging is accomplished by insuring that the range of motion of the delay line encompasses the zero optical path difference fringe for each detector pixel in the desired field-of-view. Each baseline cube is incoherent relative to all other baseline cubes and thus has only phase information relative to itself. This lost phase information is recovered by having point, or otherwise known, sources within the field-of-view. The reference source phase is known and utilized as a constraint to recover the coherent phase relation between the baseline cubes and is key to the image synthesis. Described will be the mathematical formalism, with phase referencing and results will be shown using data collected from NASA/GSFC Wide-Field Imaging Interferometry Testbed (WIIT).

Lyon, Richard G.; Leisawitz, David T.; Rinehart, Stephen A.; Memarsadeghi, Nargess; Sinukoff, Evan J.

2012-01-01

127

Wide-field feedback neurons dynamically tune early visual processing.  

PubMed

An important strategy for efficient neural coding is to match the range of cellular responses to the distribution of relevant input signals. However, the structure and relevance of sensory signals depend on behavioral state. Here, we show that behavior modifies neural activity at the earliest stages of fly vision. We describe a class of wide-field neurons that provide feedback to the most peripheral layer of the Drosophila visual system, the lamina. Using in vivo patch-clamp electrophysiology, we found that lamina wide-field neurons respond to low-frequency luminance fluctuations. Recordings in flying flies revealed that the gain and frequency tuning of wide-field neurons change during flight, and that these effects are mimicked by the neuromodulator octopamine. Genetically silencing wide-field neurons increased behavioral responses to slow-motion stimuli. Together, these findings identify a cell type that is gated by behavior to enhance neural coding by subtracting low-frequency signals from the inputs to motion detection circuits. PMID:24853944

Tuthill, John C; Nern, Aljoscha; Rubin, Gerald M; Reiser, Michael B

2014-05-21

128

Wide-field Raman imaging of dental lesions.  

PubMed

Detection of dental caries at the onset remains as a great challenge in dentistry. Raman spectroscopy could be successfully applied towards detecting caries since it is sensitive to the amount of Raman active mineral crystals, the most abundant component of enamel. Effective diagnosis requires full examination of a tooth surface via Raman mapping. Point-scan Raman mapping is not clinically relevant (feasible) due to lengthy data acquisition time. In this work, a wide-field Raman imaging system was assembled based on a high-sensitivity 2D CCD camera for imaging the mineralization status of teeth with lesions. Wide-field images indicated some lesions to be hypomineralized and others to be hypermineralized. The observations of wide-field Raman imaging were in agreement with point-scan Raman mapping. Therefore, sound enamel and lesions can be discriminated by Raman imaging of the mineral content. In conclusion, wide-field Raman imaging is a potentially useful tool for visualization of dental lesions in the clinic. PMID:24781363

Yang, Shan; Li, Bolan; Akkus, Anna; Akkus, Ozan; Lang, Lisa

2014-06-21

129

Optical interconnects for future high performance integrated circuits  

NASA Astrophysics Data System (ADS)

Miniaturization paradigm leads to a rapid performance deterioration of Copper wires in the future, despite lower dielectric constant materials between the lines. This work examines optical interconnects as an alternative for high performance silicon integrated circuits, and compares it with future metal interconnects. Both global signaling and clock distribution applications are considered. For clocking, power dissipation, where as, for global signaling, both power and delay are compared with metal-based interconnects. We show that for high switching activity, long global signaling wires, it is favorable to switch to optical interconnects on both power and delay account. Whereas, a metal-based interconnect system is more favorable for shorter links.

Kapur, Pawan; Saraswat, Krishna C.

2003-03-01

130

Fiber optics for the future - wavelength division multiplexing  

NASA Technical Reports Server (NTRS)

Optical wavelength division multiplexing (WDM) systems, with signals transmitted on different wavelengths through a single fiber, can have increased information capacity and fault isolation properties over single wavelength optical systems. This paper describes a typical WDM system. The applicability of future standards to such a system are discussed. Also, a state-of-the-art survey of optical multimode components which could be used to implement the system are made. The components to be surveyed are sources, multiplexers, and detectors. Emphasis is given to the demultiplexer techniques which are the major developmental components in the WDM system.

Spencer, J. L.

1982-01-01

131

EUV band pass filters for the ROSAT Wide Field Camera  

Microsoft Academic Search

Large-area thin-film bandpass filters have been constructed to provide four wavelength bands for the Wide Field Camera telescope on the Rosat satellite. The filters consist of a polycarbonate substrate coated with one of carbon, beryllium, or aluminum; additionally, a tin\\/aluminum filter is also available. These provide wavelength bands of mean wavelength 100, 140, 180, and 600 angstroms, respectively. This paper

B. J. Kent; D. H. Reading; B. M. Swinyard; P. H. Spurrett; E. B. Graper

1990-01-01

132

In-Flight Performance of Wide Field Camera 3  

NASA Technical Reports Server (NTRS)

Wide Field Camera 3 (WFC3), a powerful new UVNisible/IR imager, was installed into HST during Servicing Mission 4. After a successful commissioning in the Servicing Mission Orbital Verification program, WFC3 has been engaged in an exciting program of scientific observations. I review here the in-flight scientific performance of the instrument, addressing such topics as image quality, sensitivity, detector performance, and stability.

Kimble, Randy

2010-01-01

133

Metal multilayer mirrors for EUV wide field telescopes  

Microsoft Academic Search

Metal multilayer mirrors have been designed for the ALEXIS satellite, which is to carry six wide field telescopes to perform an all-sky survey in three or four narrow wavelength bands in the EUV. Comprised of alternating layers of molybdenum and silicon, the mirrors are optimized to provide maximum reflectivity at angles from 11.5 to 17\\/degree\\/ off normal incidence and at

B. W. Smith; J. J. Bloch; D. Roussel-Dupre

1989-01-01

134

Wide Field - Planetary Camera Instrument Handbook v. 3.0  

NASA Astrophysics Data System (ADS)

The WF/PC is a dual two-dimensional spectrophotometer with rudimentary polarimetric and transmission-grating capabilities. The instrument was designed to operate from 1150 A to 11,000 A with a resolution of 0.1 arcsec per pixel (wide field camera, f/12.9) or 0.043 arcsec per pixel (planetary camera, f/30) using an array of CCD detectors.

Mackenty, J. W.; et al.

1992-04-01

135

The JPL Optical Communications Telescope Laboratory Test Bed for the Future Optical Deep Space Network  

Microsoft Academic Search

The lower power consumption and lower mass of high-bandwidth optical telecom- munications relative to RF telecommunications make laser communication technol- ogy extremely attractive for returning data from future NASA\\/JPL deep-space probes. JPL is building a research and development optical communications tele- scope laboratory (OCTL) at its Table Mountain Facility in Southern California to evaluate strategies for supporting operations from future

K. E. Wilson; N. Page; J. Wu; M. Srinivasan

2003-01-01

136

A ROSAT Wide Field Camera search for XUV bursts  

NASA Technical Reports Server (NTRS)

We have searched the ROSAT Wide Field Camera all-sky survey for shorttime-scale (less than 50 s) XUV bursts down to a limiting count of 5 x 10 exp -3 count/sq arcmin, corresponding to an incident flux of about 3 x 10 exp -10 erg/sq cm. In a total observation period of 171 d covering the entire sky, we found no evidence for such events. The present results are used to place limits on the log N-log S relation for gamma-ray bursts and constraints on the spectral shape of the previously reported ultrasoft X-ray transients.

Owens, Alan; Page, Clive G.; Sembay, S.; Schaefer, Bradley E.

1993-01-01

137

Dither and drizzle strategies for Wide Field Camera 3  

NASA Astrophysics Data System (ADS)

Hubble's 20th anniversary observation of Herbig-Haro object HH 901 in the Carina Nebula is used to illustrate observing strategies and corresponding data reduction methods for the new Wide Field Camera 3 (WFC3), which was installed during Servicing Mission 4 in May 2009. The key issues for obtaining optimal results with offline Multidrizzle processing of WFC3 data sets are presented. These pragmatic instructions in "cookbook" format are designed to help new WFC3 users quickly obtain good results with similar data sets.

Mutchler, Max

2010-07-01

138

A trend filtering algorithm for wide-field variability surveys  

NASA Astrophysics Data System (ADS)

We show that various systematics related to certain instrumental effects and data reduction anomalies in wide-field variability surveys can be efficiently corrected by a trend filtering algorithm (TFA) applied to the photometric time-series produced by standard data pipelines. Statistical tests, performed on the data base of the HAT Network project, show that by the application of this filtering method the cumulative detection probability of periodic transits increases by up to 0.4 for variables brighter than 11 mag, with a trend of increasing efficiency toward brighter magnitudes. We also show that the TFA can be used for the reconstruction of periodic signals by iteratively filtering out systematic distortions.

Kovács, Géza; Bakos, Gáspár; Noyes, Robert W.

2005-01-01

139

Wide field fluorescence imaging in narrow passageways using scanning fiber endoscope technology  

NASA Astrophysics Data System (ADS)

An ultrathin scanning fiber endoscope (SFE) has been developed for high resolution imaging of regions in the body that are commonly inaccessible. The SFE produces 500 line color images at 30 Hz frame rate while maintaining a 1.2-1.7 mm outer diameter. The distal tip of the SFE houses a 9 mm rigid scan engine attached to a highly flexible tether (minimum bend radius < 8 mm) comprised of optical fibers and electrical wires within a protective sheath. Unlike other ultrathin technologies, the unique characteristics of this system have allowed the SFE to navigate narrow passages without sacrificing image quality. To date, the SFE has been used for in vivo imaging of the bile duct, esophagus and peripheral airways. In this study, the standard SFE operation was tailored to capture wide field fluorescence images and spectra. Green (523 nm) and blue (440 nm) lasers were used as illumination sources, while the white balance gain values were adjusted to accentuate red fluorescence signal. To demonstrate wide field fluorescence imaging of small lumens, the SFE was inserted into a phantom model of a human pancreatobiliary tract and navigated to a custom fluorescent target. Both wide field fluorescence and standard color images of the target were captured to demonstrate multimodal imaging.

Lee, Cameron M.; Chandler, John E.; Seibel, Eric J.

2010-02-01

140

A Practical Implementation of the Wide Field InfraRed Survey Telescope WFIRST  

NASA Astrophysics Data System (ADS)

The Wide-Field Infrared Survey Telescope mission (WFIRST) combines a wide field imager and a wide field slitless spectrometer. It is intended to study dark energy via measurement of the expansion history of the universe and the growth of large-scale structure, and to provide tight constraints on the equation of state of dark energy and test the validity of general relativity. In addition, this mission will survey the Galactic Bulge for exoplanet microlensing events, delivering a rapid reobservation cadence for extended periods of time. During this past year we have developed optical techniques that deliver a well-corrected long focus image field simultaneously with a short focus spectroscopic field using a corrected prism disperser and a focal reducer. This advance allows unprecedented survey rates for combined BAO and WL surveys. Other payload features allow extended dwell times on the Galactic Bulge for microlensing. We present four practical implementations of the WFIRST payload that can meet the anticipated mission requirements. Options for simultaneous or staggered imaging and spectroscopy as well as the required plate scale change with a focal TMA are presented along with payload accommodation study results.

Sholl, Michael; Lampton, M. L.; Levi, M. E.

2011-01-01

141

Wide field-of-view dual-band multispectral muzzle flash detection  

NASA Astrophysics Data System (ADS)

Sensor technologies are undergoing revolutionary advances, as seen in the rapid growth of multispectral methodologies. Increases in spatial, spectral, and temporal resolution, and in breadth of spectral coverage, render feasible sensors that function with unprecedented performance. A system was developed that addresses many of the key hardware requirements for a practical dual-band multispectral acquisition system, including wide field of view and spectral/temporal shift between dual bands. The system was designed using a novel dichroic beam splitter and dual band-pass filter configuration that creates two side-by-side images of a scene on a single sensor. A high-speed CMOS sensor was used to simultaneously capture data from the entire scene in both spectral bands using a short focal-length lens that provided a wide field-of-view. The beam-splitter components were arranged such that the two images were maintained in optical alignment and real-time intra-band processing could be carried out using only simple arithmetic on the image halves. An experiment related to limitations of the system to address multispectral detection requirements was performed. This characterized the system's low spectral variation across its wide field of view. This paper provides lessons learned on the general limitation of key hardware components required for multispectral muzzle flash detection, using the system as a hardware example combined with simulated multispectral muzzle flash and background signatures.

Montoya, J.; Melchor, J.; Spiliotis, P.; Taplin, L.

2013-06-01

142

Comparing Type Ia Supernovae from Targeted and Wide Field Surveys  

NASA Astrophysics Data System (ADS)

We compare the Type Ia Supernovae discovered by ROTSE-IIIb to other surveys including the targeted LOSS and wide field SDSS-II surveys. Although modest in size, the ROTSE-IIIb sample is both non-targeted and spectroscopically complete--and thus unique among supernova surveys. About half of the Type Ia supernovae found by ROTSE reside in dwarf galaxies, which is a much higher fraction than reported in other wide-field surveys that also use image subtraction techniques to remove the blinding glare of bright host galaxies. We calculate the volumetric SN Ia rate from the ROTSE-IIIb sample. The results, while of low significance, are supportive of a higher overall SN Ia rate than has previously been published, which combined with the surplus in dwarf hosts may indicate under counting of the contribution from low-luminosity hosts in prior works. We also compare the SN Ia luminosity function reported by LOSS to the volume limited SDSS-II sample and find the later lacking in low-luminosity events.

Quimby, Robert; Yuan, F.; Akerlof, C.; Wheeler, J. C.; Warren, M. S.

2012-01-01

143

Science with a Wide-field UV Transient Explorer  

NASA Astrophysics Data System (ADS)

The time-variable electromagnetic sky has been well-explored at a wide range of wavelengths. In contrast, the ultra-violet (UV) variable sky is relatively poorly explored, even though it offers exciting scientific prospects. Here, we review the potential scientific impact of a wide-field UV survey on the study of explosive and other transient events, as well as known classes of variable objects, such as active galactic nuclei and variable stars. We quantify our predictions using a fiducial set of observational parameters which are similar to those envisaged for the proposed ULTRASAT mission. We show that such a mission would be able to revolutionize our knowledge about massive star explosions by measuring the early UV emission from hundreds of events, revealing key physical parameters of the exploding progenitor stars. Such a mission would also detect the UV emission from many tens of tidal-disruption events of stars by supermassive black holes at galactic nuclei and enable a measurement of the rate of such events. The overlap of such a wide-field UV mission with existing and planned gravitational-wave and high-energy neutrino telescopes makes it especially timely.

Sagiv, I.; Gal-Yam, A.; Ofek, E. O.; Waxman, E.; Aharonson, O.; Kulkarni, S. R.; Nakar, E.; Maoz, D.; Trakhtenbrot, B.; Phinney, E. S.; Topaz, J.; Beichman, C.; Murthy, J.; Worden, S. P.

2014-04-01

144

Optical interferometry in Antarctica: a future for European astronomy?  

NASA Astrophysics Data System (ADS)

During the next decade, the European Very Large Telescope Interferometer (vlti) will remain one of the most productive existing optical interferometers. Costly space missions will not soon provide new steps in sensitivity, imaging capability and higher resolution. Hence, although they represent the long term future, it is wise for groud-based interferometry to look beyond the horizon 2020 and to prepare for it, even if large projects mobilize today nearly all available European resources. The context of the vlti decision, the situation in optical interferometry today and the critical role of site seeing for performances are recalled. Given what is known of Antarctica sites, it appears relevant to pursue their study for interferometric use. Possible steps may be within the European Southern Observatory for seeing studies and independently at Concordia with a modest interferometer (e.g. alladin). It may pave the way for the future of interferometry, to be decided in a decade or so.

Léna, P.

145

Ultra Wide-Field Telescope WIDGET for Observing GRBs and SNe  

NASA Astrophysics Data System (ADS)

We have constructed an ultra wide field telescope named WIDGET to observepossible prompt optical emission associated with GRBs or shock breakout ofSN explosions. Performing the simultaneous observation with GRB satellitesuch as HETE-2 and Swift, the telescope should have an ultra-wide FOV. TheWIDGET telescope has 70 degrees FOV in each side which covers almost all ofthe FOV of those satellites. WIDGET is located at Akeno Observatory inJapan where is about 150km away from Tokyo. The telescope is in operationsince June 2004. We will present the status and early results of one andhalf year observations in the conference.

Tamagawa; Tashiro; Urata; Abe; Onda; Usui; Azuma; Kuwahara

2006-02-01

146

Imaging without lenses: achievements and remaining challenges of wide-field on-chip microscopy  

PubMed Central

We discuss unique features of lens-free computational imaging tools and report some of their emerging results for wide-field on-chip microscopy, such as the achievement of a numerical aperture (NA) of ~0.8–0.9 across a field of view (FOV) of more than 20 mm2 or an NA of ~0.1 across a FOV of ~18 cm2, which corresponds to an image with more than 1.5 gigapixels. We also discuss the current challenges that these computational on-chip microscopes face, shedding light on their future directions and applications.

Greenbaum, Alon; Luo, Wei; Su, Ting-Wei; Gorocs, Zoltan; Xue, Liang; Isikman, Serhan O; Coskun, Ahmet F; Mudanyali, Onur; Ozcan, Aydogan

2012-01-01

147

The wide-field imaging interferometry testbed: II. Characterization and calibration  

NASA Astrophysics Data System (ADS)

We discuss the procedure used to characterize the Wide-Field Imaging Interferometry Testbed (WIIT) components and system, including spectral transmission, throughput, wavefront quality, mechanical and thermal stability, and susceptibility to turbulence. The sources of uncertainty and visibility loss are identified and evaluated, and we briefly discuss measures taken to mitigate these effects. We further discuss calibration techniques which can be used to compensate for visibility loss factors, and describe the applicability of these calibration techniques to the future space-based far-IR interferometry missions SPIRIT (Space Infrared Interferometric Telescope) and SPECS (Submillimeter Probe of the Evolution of Cosmic Structure).

Rinehart, Stephen A.; Armstrong, J. T.; Frey, Bradley J.; Kirk, Jeff; Leisawitz, David T.; Leviton, Douglas B.; Lobsinger, Luke W.; Lyon, Richard G.; Martino, Anthony J.; Pauls, Thomas A.; Mundy, Lee G.; Sears, E.

2004-10-01

148

Optical gap solitons: Past, present, and future; theory and experiments  

NASA Astrophysics Data System (ADS)

Optical gap solitons refer to nonlinear waves propagating in optical fibers whose linear refractive index has a periodic variation. Stationary gap solitons came to light first in 1987 [Chen and Mills, Phys. Rev. Lett. 58, 160 (1987)] two years later, they re-emerge in Christodoulides and Joseph [Phys. Rev. Lett. 62, 1746 (1989)] and are first extended to a more general traveling wave form in Aceves and Wabnitz [Phys. Lett. A 141, 37 (1989)]. But it was not until seven years later, that the first experimental demonstration [Eggleton et al., Phys. Rev. Lett. 76, 1627 (1996); J. Opt. Soc. Am. B 14, 2980 (1997)] was reported. Since then, there has been an increase in the study of the dynamics and applications of such solitons. This paper is a brief survey of some of the ongoing and future research on optical gap solitons.

Aceves, Alejandro B.

2000-09-01

149

Wide-field-of-view solar occultation gas filter correlation radiometer for stratospheric methane measurements from a sounding rocket  

NASA Astrophysics Data System (ADS)

A wide field of view Gas Filter Correlation Radiometer (GFCR) has been developed to make solar occultation measurements of the vertical methane distribution in the stratosphere from a sounding rocket platform. The GFCR has demonstrated a 50° solar acceptance angle that allows for a GFCR measurement during every rotation of the payload without active orientation control. The flat surface of a plano-convex ZnSe lens was etched to diffuse the projected image of the sun. By diffusing the incident solar radiation through a wide angle, sufficient radiation could be directed to the collimating GFCR optics even when the optical axis points as far as ± 25° away from the Sun. The system can be configured to measure other gaseous species with spectral bands in the 2 6 ?m region by simply changing the bandpass filter and the correlation gas. In a laboratory calibration, the optical density of methane in a test cell was varied from 10^-4 to 10-2 atm·m as the GFCR correlation cell optical density was held at 2.5×10-3 atm·m. The process showed that measurements with a signal to noise ratio > 30:1 can be expected when the system operates in altitudes from 25 to 40 km. The GFCR performed with a correlation of 99.7% to the prediction of a theoretical model created with the HITRAN database. Sensitivity to gas distributions at other altitudes can be optimized by changing the gas pressure in the correlation cell. The payload featuring the GFCR is scheduled to be launched on an Enhanced Orion sub-orbital sounding rocket from NASA Wallops Flight Facility in April 2003. Future applications include validation and truthing for space-born remote sensing systems.

Nunnally, William C.; Holland, Stephen K.; Laufer, Gabriel

2003-04-01

150

A Parallel Imaging Approach to Wide-field MR Microscopy  

PubMed Central

Magnetic resonance microscopy (MRM), suggested in the earliest papers on MRI, has always been limited by the low signal-to-noise ratio (SNR) resulting from the small voxel size. MRM has largely been enabled by the use of microcoils which provide the SNR improvement required to overcome this limitation. Concomitant with the small coils is a small field-of-view, which limits the use of MRM as a histological tool or for imaging large regions in general. This paper describes initial results in wide field-of-view MR microscopy using a large array of narrow, parallel coils, which provides an SNR enhancement as well as the ability to use parallel imaging techniques. Comparison images made between a volume coil and the proposed technique demonstrate reductions in imaging time of over 100 with no loss in SNR or resolution.

McDougall, Mary Preston; Wright, Steven M.

2011-01-01

151

Wide Field X-Ray Telescope Mission Concept Study Results  

NASA Technical Reports Server (NTRS)

The Wide Field X-Ray Telescope (WFXT) is an astrophysics mission concept for detecting and studying extra-galactic x-ray sources, including active galactic nuclei and clusters of galaxies, in an effort to further understand cosmic evolution and structure. This Technical Memorandum details the results of a mission concept study completed by the Advanced Concepts Office at NASA Marshall Space Flight Center in 2012. The design team analyzed the mission and instrument requirements, and designed a spacecraft that enables the WFXT mission while using high heritage components. Design work included selecting components and sizing subsystems for power, avionics, guidance, navigation and control, propulsion, structures, command and data handling, communications, and thermal control.

Hopkins, R. C.; Thomas, H. D.; Fabisinski, L. L.; Baysinger, M.; Hornsby, L. S.; Maples, C. D.; Purlee, T. E.; Capizzo, P. D.; Percy, T. K.

2014-01-01

152

Wide-Field-of-View, High-Resolution, Stereoscopic Imager  

NASA Technical Reports Server (NTRS)

A device combines video feeds from multiple cameras to provide wide-field-of-view, high-resolution, stereoscopic video to the user. The prototype under development consists of two camera assemblies, one for each eye. One of these assemblies incorporates a mounting structure with multiple cameras attached at offset angles. The video signals from the cameras are fed to a central processing platform where each frame is color processed and mapped into a single contiguous wide-field-of-view image. Because the resolution of most display devices is typically smaller than the processed map, a cropped portion of the video feed is output to the display device. The positioning of the cropped window will likely be controlled through the use of a head tracking device, allowing the user to turn his or her head side-to-side or up and down to view different portions of the captured image. There are multiple options for the display of the stereoscopic image. The use of head mounted displays is one likely implementation. However, the use of 3D projection technologies is another potential technology under consideration, The technology can be adapted in a multitude of ways. The computing platform is scalable, such that the number, resolution, and sensitivity of the cameras can be leveraged to improve image resolution and field of view. Miniaturization efforts can be pursued to shrink the package down for better mobility. Power savings studies can be performed to enable unattended, remote sensing packages. Image compression and transmission technologies can be incorporated to enable an improved telepresence experience.

Prechtl, Eric F.; Sedwick, Raymond J.

2010-01-01

153

Restoration of observed image with an unknown space-variant blur from wide-field telescope  

NASA Astrophysics Data System (ADS)

The field-of-view (FOV) of wide-field telescope is mostly beyond the scope of isoplanatic angle. Though the aberrated wave-front within a limited range close to guide star could be corrected accurately by adaptive-optics (AO) system, the image quality of object region deviation from guide star is dropped severely. The post-processing technique to restore degraded image observed from wide-field telescope is a good compensation for the limit of AO system. Restoration method of space-variant point spread function (PSF) degraded image which are used to overcome the turbulence-induced anisoplanatic effect, can improve image quality in the whole field of view of wide-field telescope, and restore image resolution to optical diffraction-limited level in free space. A multi-frame blind deconvolution restoration algorithm based on image sectioning method is presented here. The image is divided into several subimages, where the PSF of each subimage is assumed to be space-invariant. The conjugate gradient optimization algorithm based on maximum likelihood estimation (MLE) in space domain is adopted to estimate the space-invariant PSF and object information in each block. In order to reduce blocking artifacts at the subregion boundaries, larger, overlapping subregions as well as the Mumford- Shah regularization are used, and then the restored sections are extracted from their center. The resolution of the restored image using 5 satellite model blurred image frames through image sectioning method is enhanced significantly, compared to the space-invariant PSF restoration approach. There are more details about the original object, and it shows the proposed algorithm is valid.

He, Chaolan; Wei, Honggang; Shen, Mangzuo

154

Temporally focused wide-field two-photon microscopy: Paraxial to vectorial  

PubMed Central

Temporal focusing allows for optically sectioned wide-field microscopy. The optical sectioning arises because this method takes a pulsed input beam, stretches the pulses by diffracting off a grating, and focuses the stretched pulses such that only at the focal plane are the pulses re-compressed. This approach generates nonlinear optical processes at the focal plane and results in depth discrimination. Prior theoretical models of temporal focusing processes approximate the contributions of the different spectral components by their mean. This is valid for longer pulses that have narrower spectral bandwidth but results in a systematic deviation when broad spectrum, femtosecond pulses are used. Further, prior model takes the paraxial approximation but since these pulses are focused with high numerical aperture (NA) objectives, the effects of the vectorial nature of light should be considered. In this paper we present a paraxial and a vector theory of temporal focusing that takes into account the finite spread of the spectrum. Using paraxial theory we arrive at an analytical solution to the electric field at the focus for temporally focused wide-field two-photon (TF2p) microscopy as well as in the case of a spectrally chirped input beam. We find that using paraxial theory while accounting for the broad spectral spread gives results almost twice vector theory. Experiment results agree with predictions of the vector theory giving an axial full-width half maximum (FWHM) of 2.1 ?mand 1.8 ?mrespectively as long as spectral spread is taken into account. Using our system parameters, the optical sectioning of the TF2p microscope is found to be 8 ?m. The optical transfer function (OTF) of a TF2p microscope is also derived and is found to pass a significantly more limited band of axial frequencies than a point scanning two-photon (2p) microscope or a single photon (1p) confocal microscope.

Yew, Elijah Y. S.; Sheppard, Colin J. R.; So, Peter T. C.

2013-01-01

155

Designing contact lenses for a wide field of view via ocular wavefront tomography  

PubMed Central

Purpose Correcting the off-axis wavefront aberration is potentially important for peripheral vision, for diagnostic imaging of the retina, and for influencing refractive development. A new technique called ocular wavefront tomography (OWT) was adapted to optimize the design of contact lenses to improve the eye's peripheral optical quality. Methods OWT is a technique for customizing a multi-surface model eye to mimic the off-axis wavefront aberrations for an individual eye. This technique was adapted for contact lens design by establishing clear design goals for the eye + contact lens system. To demonstrate the method we optimized the shape of an aspheric and bifocal contact lens to correct a wide angle model eye with ?2D foveal myopia. Two strategies for correction reflected alternative design goals: 1) to fully correct central vision while also improving optical quality peripherally to enhance vision and retinal imaging, or 2) fully correct central vision while introducing a degree of peripheral myopia relative to central vision in order to slow myopia progression. Results The OWT technique successfully produced aspheric and bifocal contact lens designs over a wide field of view. In addition to correcting foveal vision, the optimized contact lens designs either 1) improved the retinal image quality across the visual field (< 45°) significantly to obtain a visual performance and retinal imaging benefit or 2) produced the desired level of myopia in the peripheral field to obtain a refractive development benefit. Conclusion The OWT technique is a validated tool to optimize contact lens design over a wide field.

Wei, Xin; Thibos, Larry

2010-01-01

156

Space infrared telescope facility wide field and diffraction limited array camera (IRAC)  

NASA Technical Reports Server (NTRS)

The wide-field and diffraction limited array camera (IRAC) is capable of two-dimensional photometry in either a wide-field or diffraction-limited mode over the wavelength range from 2 to 30 microns with a possible extension to 120 microns. A low-doped indium antimonide detector was developed for 1.8 to 5.0 microns, detectors were tested and optimized for the entire 1.8 to 30 micron range, beamsplitters were developed and tested for the 1.8 to 30 micron range, and tradeoff studies of the camera's optical system performed. Data are presented on the performance of InSb, Si:In, Si:Ga, and Si:Sb array detectors bumpbonded to a multiplexed CMOS readout chip of the source-follower type at SIRTF operating backgrounds (equal to or less than 1 x 10 to the 8th ph/sq cm/sec) and temperature (4 to 12 K). Some results at higher temperatures are also presented for comparison to SIRTF temperature results. Data are also presented on the performance of IRAC beamsplitters at room temperature at both 0 and 45 deg angle of incidence and on the performance of the all-reflecting optical system baselined for the camera.

Fazio, Giovanni G.

1988-01-01

157

A wide-field Imaging FTS for the Molecular Hydrogen Explorer space mission (H2EX)  

NASA Astrophysics Data System (ADS)

The Molecular Hydrogen Explorer (H2EX) proposed for the 2015 - 2025 Cosmic Vision Call issued by ESA in 2007 was designed to make surveys of the molecular gas from its first rotational lines in various extragalactic and galactic sites. The design study led to the proposition of a mid-infrared (8 to 29 ?m) Imaging Fourier transform Spectrometer (IFTS) making possible integral field spectroscopy on a 20' wide field and a maximum resolution up to 3×104 at 10 ?m. To reach this goal, an all-mirror payload was outlined, made of a 1.2m telescope matched to a dual output interferometer, imaging the field on two 1024×1024 Si:As IBC detectors. The payload was designed to re-use the platform developed for the Planck mission. Such a wide field and high spectral resolution IFTS on a large spectral domain can have further applications, with the necessary adaptation to each case, for future large aperture cryogenic telescopes in the mid-infrared, or in the near-infrared behind future ELTs, in a site like Dome C in Antarctica, and out of astronomy, for remote sensing of Earth atmosphere.

Maillard, J.-P.; Boulanger, F.; Longval, Y.; Fourmond, J.-J.; Bouzit, M.; Dumesnil, C.

2008-08-01

158

Wide-Field Infrared Survey Telescope (WFIRST) Interim Report  

NASA Technical Reports Server (NTRS)

The New Worlds, New Horizons (NWNH) in Astronomy and Astrophysics 2010 Decadal Survey prioritized the community consensus for ground-based and space-based observatories. Recognizing that many of the community s key questions could be answered with a wide-field infrared survey telescope in space, and that the decade would be one of budget austerity, WFIRST was top ranked in the large space mission category. In addition to the powerful new science that could be accomplished with a wide-field infrared telescope, the WFIRST mission was determined to be both technologically ready and only a small fraction of the cost of previous flagship missions, such as HST or JWST. In response to the top ranking by the community, NASA formed the WFIRST Science Definition Team (SDT) and Project Office. The SDT was charged with fleshing out the NWNH scientific requirements to a greater level of detail. NWNH evaluated the risk and cost of the JDEM-Omega mission design, as submitted by NASA, and stated that it should serve as the basis for the WFIRST mission. The SDT and Project Office were charged with developing a mission optimized for achieving the science goals laid out by the NWNH re-port. The SDT and Project Office opted to use the JDEM-Omega hardware configuration as an initial start-ing point for the hardware implementation. JDEM-Omega and WFIRST both have an infrared imager with a filter wheel, as well as counter-dispersed moderate resolution spectrometers. The primary advantage of space observations is being above the Earth's atmosphere, which absorbs, scatters, warps and emits light. Observing from above the atmosphere enables WFIRST to obtain precision infrared measurements of the shapes of galaxies for weak lensing, infrared light-curves of supernovae and exoplanet microlensing events with low systematic errors, and infrared measurements of the H hydrogen line to be cleanly detected in the 1Wide-field Infrared Sur-vey Explorer (WISE) are all space missions that have produced stunning new scientific advances by going to space to observe in the infrared. This interim report describes progress as of June 2011 on developing a requirements flowdown and an evaluation of scientific performance. An Interim Design Reference Mission (IDRM) configuration is presented that is based on the specifications of NWNH with some refinements to optimize the design in accordance with the new scientific requirements. Analysis of this WFIRST IDRM concept is in progress to ensure the capability of the observatory is compatible with the science requirements. The SDT and Project will continue to refine the mission concept over the coming year as design, analysis and simulation work are completed, resulting in the SDT s WFIRST Design Reference Mission (DRM) by the end of 2012.

Green, J.; Schechter, P.; Baltay, C.; Bean, R.; Bennett, D.; Brown, R.; Conselice, C.; Donahue, M.; Gaudi, S.; Lauer, T.; Perlmutter, S.; Rauscher, B.; Rhodes, J.; Roellig, T.; Stern, D.; Sumi, T.; Gerhels, N.; Sambruna, R.; Barry, R. K.; Content, D.; Grady, K; Jackson, C.; Kruk, J.; Melton, M.; Rioux, N.

2011-01-01

159

Numerical Characterization of the Observed Point Spread Function of the Vst Wide-Field Telescope  

NASA Astrophysics Data System (ADS)

The numerical model of the observed Point Spread Function of the VST wide-field telescope is computed over the field of view by means of the convolution of the simulation of the atmospheric seeing and the ray-tracing, Fast-Fourier-transform-based Point Spread Function of the optical configuration of the telescope. The images obtained are compressed by means of two methods, a polynomial-modulated gaussian fit and a wavelet decomposition. The compressed images are mapped over the field of view by means of the interpolation of the fit or wavelet coefficients. The original and mapped Point Spread Function images are used for the evaluation and mapping over the field of view of various intensity and position error figures. The error maps confirm the high quality of the design of the VST telescope optics. Finally, the error maps can be input into the scientific processing of the astronomical observations.

Sedmak, Giorgio; Carozza, Simone; Marra, Gabriella

2007-12-01

160

Diffuse optical tomography: Present status and its future  

NASA Astrophysics Data System (ADS)

Diffuse optical tomography (DOT) is one of the emerging modalities for the non-invasive imaging of thick biological tissues using near-infrared (NIR) light. This article reviews the fundamentals and development of DOT technology since its advent in the early 1990s, including the modeling of light propagation in biological tissues which strongly scatter and weakly absorb NIR light, the optical properties of biological tissues in the NIR wavelength range, three typical measurement methods, image reconstruction algorithms, and so forth. Then various studies are referred to for improvement of the DOT images, which are essentially low in quality due to the ill-conditioned and underdetermined problem. Studies and clinical applications presently attracting much attention are discussed in some detail. Finally, the expected future developments are summarized.

Yamada, Yukio; Okawa, Shinpei

2014-05-01

161

Twenty years of optical coherence tomography: challenges for the future  

NASA Astrophysics Data System (ADS)

Optical coherence tomography is nowadays an established imaging technique in Ophthalmology, with a key role on early detection of macular diseases, benefiting from the tremendous evolution in principles and technological developments of the last 20 years. In this paper the most important physical principles behind time-domain, spectral-domain and Fourier-domain OCT will be presented, along with examples of applications in different imaging fields, emphasizing the limitations of current systems, their performance parameters, as well as the challenges for the future within this field of development.

Carmelo Rosa, Carla

2011-05-01

162

Wide field and diffraction limited array camera for SIRTF  

NASA Technical Reports Server (NTRS)

The Infrared Array Camera for the space Infrared Telescope Facility (SIRTF/IRAC) is capable of two-dimensional photometry in either a wide field or diffraction-limited mode over the wavelength interval from 2 to 30 microns. Three different two-dimensional direct readout (DRO) array detectors will be used: Band 1-InSb or Si:In (2-5 microns) 128 x 128 pixels, Band 2-Si:Ga (5-18 microns) 64 x 64 pixels, and Band 3-Si:Sb (18-30 microns) 64 x 64 pixels. The hybrid DRO readout architecture has the advantages of low read noise, random pixel access with individual readout rates, and nondestructive readout. The scientific goals of IRAC are discussed, which are the basis for several important requirements and capabilities of the array camera: (1) diffraction-limited resolution from 2-30 microns, (2) use of the maximum unvignetted field of view of SIRTF, (3) simultaneous observations within the three infrared spectral bands, and (4) the capability for broad and narrow bandwidth spectral resolution. A strategy has been developed to minimize the total electronic and environmental noise sources to satisfy the scientific requirements.

Fazio, G. G.; Koch, D. G.; Melnick, G. J.; Tresch-Fienberg, R. M.; Willner, S. P.; Gezari, D. Y.; Lamb, G.; Shu, P.; Chin, G.; Mccreight, C. R.

1986-01-01

163

Wide field and diffraction limited array camera for SIRTF  

NASA Astrophysics Data System (ADS)

The Infrared Array Camera for the Space Infrared Telescope Facility (SIRTF/IRAC) is capable of two-dimensional photometry in either a wide field or diffraction-limited mode over the wavelength interval from 2 to 30 microns. Three different two-dimensional direct readout (DRO) array detectors are being considered: Band 1-InSb or Si:In (2-5 microns) 128 x 128 pixels, Band 2-Si:Ga (5-18 microns) 64 x 64 pixels, and Band 3-Si:Sb (18-30 microns) 64 x 64 pixels. The hybrid DRO readout architecture has the advantages of low read noise, random pixel access with individual readout rates, and nondestructive readout. The scientific goals of IRAC are discussed, which are the basis for several important requirements and capabilities of the array camera: (1) diffraction-limited resolution from 2-30 microns, (2) use of the maximum unvignetted field of view of SIRTF, (3) simultaneous observations within the three infrared spectral bands, and (4) the capability for broad and narrow bandwidth spectral resolution. A strategy has been developed to minimize the total electronic and environmental noise sources to satisfy the scientific requirements.

Fazio, G. G.; Koch, D. G.; Melnick, G. J.; Tresch-Fienberg, R. M.; Willner, S. P.; Gezari, D. Y.; Lamb, G.; Shu, P.; Chin, G.; McCreight, C. R.

1986-01-01

164

Wide field and diffraction limited array camera for SIRTF  

NASA Astrophysics Data System (ADS)

The Infrared Array Camera for the space Infrared Telescope Facility (SIRTF/IRAC) is capable of two-dimensional photometry in either a wide field or diffraction-limited mode over the wavelength interval from 2 to 30 microns. Three different two-dimensional direct readout (DRO) array detectors will be used: Band 1-InSb or Si:In (2-5 microns) 128 x 128 pixels, Band 2-Si:Ga (5-18 microns) 64 x 64 pixels, and Band 3-Si:Sb (18-30 microns) 64 x 64 pixels. The hybrid DRO readout architecture has the advantages of low read noise, random pixel access with individual readout rates, and nondestructive readout. The scientific goals of IRAC are discussed, which are the basis for several important requirements and capabilities of the array camera: (1) diffraction-limited resolution from 2-30 microns, (2) use of the maximum unvignetted field of view of SIRTF, (3) simultaneous observations within the three infrared spectral bands, and (4) the capability for broad and narrow bandwidth spectral resolution. A strategy has been developed to minimize the total electronic and environmental noise sources to satisfy the scientific requirements.

Fazio, G. G.; Koch, D. G.; Melnick, G. J.; Tresch-Fienberg, R. M.; Willner, S. P.; Gezari, D. Y.; Lamb, G.; Shu, P.; Chin, G.; McCreight, C. R.

165

Wide-field Infrared Survey Explorer Science Payload Update  

NASA Astrophysics Data System (ADS)

The Wide Field Infrared Survey Explorer is a NASA Medium Class Explorer mission to perform a high-sensitivity, high resolution, all-sky survey in four infrared wavelength bands. The science payload is a 40 cm aperture cryogenically cooled infrared telescope with four 10242 infrared focal plane arrays covering from 2.8 to 26 µm. Mercury cadmium telluride (MCT) detectors are used for the 3.3 µm and 4.6 µm channels, and Si:As detectors are used for the 12 µm and 23 µm wavelength channels. A cryogenic scan mirror freezes the field of view on the sky over the 9.9-second frame integration time. A two-stage solid hydrogen cryostat provides cooling to temperatures less than 17 K and 8.3 K at the telescope and Si:As focal planes, respectively. The science payload collects continuous data on orbit for the seven-month baseline mission with a goal to support a year-long mission. As of the writing of this paper, the payload subassemblies are complete and have been fully integrated. The integrated payload is now undergoing environmental testing and performance characterization. This poster provides a payload overview and discusses instrument status and preliminary test results.

Larsen, Mark; Mainzer, A.; Cardon, J.; Larsen, K.; Elwell, J.; Lloyd, B.; Latvakoski, H.; Drake, J.

2009-01-01

166

Astrophysical False Positives Encountered in Wide-Field Transit Searches  

NASA Astrophysics Data System (ADS)

Wide-field photometric transit surveys for Jupiter-sized planets are inundated by astrophysical false positives, namely systems that contain an eclipsing binary and mimic the desired photometric signature. We discuss several examples of such false alarms. These systems were initially identified as candidates by the PSST instrument at Lowell Observatory. For three of the examples, we present follow-up spectroscopy that demonstrates that these systems consist of (1) an M-dwarf in eclipse in front of a larger star, (2) two main-sequence stars presenting grazing-incidence eclipses, and (3) the blend of an eclipsing binary with the light of a third, brighter star. For an additional candidate, we present multi-color follow-up photometry during a subsequent time of eclipse, which reveals that this candidate consists of a blend of an eclipsing binary and a physically unassociated star. We discuss a couple indicators from publicly-available catalogs that can be used to identify which candidates are likely giant stars, a large source of the contaminants in such surveys.

Charbonneau, David; Brown, Timothy M.; Dunham, Edward W.; Latham, David W.; Looper, Dagny L.; Mandushev, Georgi

2004-06-01

167

Wide Field Observations of Molecular Outflows in the Near Infrared  

NASA Astrophysics Data System (ADS)

Encouraged by the successful survey of molecular outflows in the K' band by Hodapp (1994), several groups in America and abroad are carrying out similar surveys of these objects in the molecular hydrogen v=1-0 2.12\\mum emission. The 2.12\\mum line traces in most cases the shock excited gas, avoids too much contamination from the continuum emission and therefore delineates fainter structures than the broad band filters. We present wide field observations of two molecular outflows, LkHa234 and S187, taken with new infrared camera at the Fred L. Whipple 1.2m telescope. The images were taken at the 1-0 2.12\\mum and 2-1 2.25\\mum molecular hydrogen lines, plus continuum at 2.22\\mum. The combined images cover a field of view (FOV) of ~ 7\\arcmin. The LkHa234 images concentrate on the East side of the flow, and are complementary to the work by Schultz et al (1997). Our images show a more rich structure of shock excited gas, and the perhaps the presence of a second jet. Similarly our S187 images with a larger FOV than those of Salas et al. 1997, indicate the presence of a counter-jet arising from the NIRS 1 source, and perhaps another jet centered 4\\arcmin NW away. Hodapp, K.W. 1994, ApJS, 94, 615 Salas, L., Cruz-Gonzalez, I., & Porras, A. 1997 ApJ (in press). Schultz, A.S.B., Rank, D.M., Temi, P., Holbrook, J.C. in ``Low Mass Star Formation from Infall to Outflow'', Ed. F Malbet & A. Castets, p 39

Noriega-Crespo, A.; Garnavich, P. M.

1998-01-01

168

Astrometric Calibration of Digitized Wide-Field Photographic Plates  

NASA Astrophysics Data System (ADS)

8000 photographic plates originally taken at Maria Mitchell Observatory from 1913 to 1996 were scanned and digitized in 2002-2003. The resulting scans are stored in TIFF format. We have investigated the use of currently existing tools to convert plate coordinates to RA and Dec to ready the scans for inclusion in the National Virtual Observatory. This involves converting the scans to FITS format and adding WCS headers. Five of the digitized images, with slightly different centers, covering 13° x 16° in Cygnus, were calibrated using the CDS Aladin program version 3.6. An initial Tangent Plane fit was produced by entering parameters applicable for the MMO plates. The images were first calibrated by parameters. The calibration was refined by matching stars images with their positions by overlaying the positions from the Bright Star Catalog. Once a reasonably accurate calibration has been determined, additional star catalogs can be used to refine the calibration. We find that the accuracy of the calibration for a Tangent Plane is not heavily dependent upon the number of stars used. Using a simple Tangent Plane model on these wide-field plates, the coordinates of objects near the edges of the plate often differ from coordinates of objects in the catalog by up to an arcminute. As a check, we also used the WCS Tools programs written by Doug Mink at the Harvard-Smithsonian CfA, and they yield the same results. A satisfactory astrometric calibration which covers the whole field will require the use of higher order polynomials. This project was supported by the NSF/REU grant AST-0354056, the NASA/AAS Small Research Grant Program and the Nantucket Maria Mitchell Association.

Boyce, Peter B.; Truong, P. N.

2006-12-01

169

Fundamental study of flow field generated by rotorcraft blades using wide-field shadowgraph  

NASA Technical Reports Server (NTRS)

The vortex trajectory and vortex wake generated by helicopter rotors are visualized using a wide-field shadowgraph technique. Use of a retro-reflective Scotchlite screen makes it possible to investigate the flow field generated by full-scale rotors. Tip vortex trajectories are visible in shadowgraphs for a range of tip Mach number of 0.38 to 0.60. The effect of the angle of attack is substantial. At an angle of attack greater than 8 degrees, the visibility of the vortex core is significant even at relatively low tip Mach numbers. The theoretical analysis of the sensitivity is carried out for a rotating blade. This analysis demonstrates that the sensitivity decreases with increasing dimensionless core radius and increases with increasing tip Mach number. The threshold value of the sensitivity is found to be 0.0015, below which the vortex core is not visible and above which it is visible. The effect of the optical path length is also discussed. Based on this investigation, it is concluded that the application of this wide-field shadowgraph technique to a large wind tunnel test should be feasible. In addition, two simultaneous shadowgraph views would allow three-dimensional reconstruction of vortex trajectories.

Parthasarathy, S. P.; Cho, Y. I.; Back, L. H.

1985-01-01

170

Wide Field Views of M31's dE Satellites: NGC 147 and NGC 185  

NASA Astrophysics Data System (ADS)

Panoramic imaging studies of the M31 halo are revealing a wealth of previously-unknown faint tidal debris [e.g. 1] suggesting that it presents a hostile environment for dwarf galaxies to live in. NGC 185(MV = -15.6) and NGC 147(MV = -15.1) are dwarf elliptical (dE) satellites of M31 which currently reside in the remote outer halo (RM31~160 kpc). Given their similarity to more distant, unresolved, dEs, NGC 147 and NGC 185 are ideal workplaces to carry out detailed studies in dEs. While NGC 147 and 185 have been studied extensively in the past, almost all previous studies have been of small field-of-view. Our ongoing wide-field analysis will allow a thorough examination of the global content and structure of these systems and enable us to assess the extent to which they have previously interacted with M31 as well as each other. We present first results from our ongoing analysis of wide-field near-IR and optical imagery of these systems which we are using to derive the first truly global views of their overall structures and stellar contents. In particular, UKIRT/WFCAM JHK data are used to identify and analyse luminous asymptotic giant branch (AGB) stars in NGC 147 and NGC 185 and separate out C-rich and O-rich populations while INT/WFC Vi data are used to analyse the red giant branch (RGB) populations.

Noël, N. E. D.; Ferguson, A. M. N.; Irwin, M. J.

2010-06-01

171

Three-Dimensional Resolution Doubling in Wide-Field Fluorescence Microscopy by Structured Illumination  

PubMed Central

Structured illumination microscopy is a method that can increase the spatial resolution of wide-field fluorescence microscopy beyond its classical limit by using spatially structured illumination light. Here we describe how this method can be applied in three dimensions to double the axial as well as the lateral resolution, with true optical sectioning. A grating is used to generate three mutually coherent light beams, which interfere in the specimen to form an illumination pattern that varies both laterally and axially. The spatially structured excitation intensity causes normally unreachable high-resolution information to become encoded into the observed images through spatial frequency mixing. This new information is computationally extracted and used to generate a three-dimensional reconstruction with twice as high resolution, in all three dimensions, as is possible in a conventional wide-field microscope. The method has been demonstrated on both test objects and biological specimens, and has produced the first light microscopy images of the synaptonemal complex in which the lateral elements are clearly resolved.

Gustafsson, Mats G. L.; Shao, Lin; Carlton, Peter M.; Wang, C. J. Rachel; Golubovskaya, Inna N.; Cande, W. Zacheus; Agard, David A.; Sedat, John W.

2008-01-01

172

Lensless wide-field fluorescent imaging on a chip using compressive decoding of sparse objects.  

PubMed

We demonstrate the use of a compressive sampling algorithm for on-chip fluorescent imaging of sparse objects over an ultra-large field-of-view (>8 cm(2)) without the need for any lenses or mechanical scanning. In this lensfree imaging technique, fluorescent samples placed on a chip are excited through a prism interface, where the pump light is filtered out by total internal reflection after exciting the entire sample volume. The emitted fluorescent light from the specimen is collected through an on-chip fiber-optic faceplate and is delivered to a wide field-of-view opto-electronic sensor array for lensless recording of fluorescent spots corresponding to the samples. A compressive sampling based optimization algorithm is then used to rapidly reconstruct the sparse distribution of fluorescent sources to achieve approximately 10 microm spatial resolution over the entire active region of the sensor-array, i.e., over an imaging field-of-view of >8 cm(2). Such a wide-field lensless fluorescent imaging platform could especially be significant for high-throughput imaging cytometry, rare cell analysis, as well as for micro-array research. PMID:20588904

Coskun, Ahmet F; Sencan, Ikbal; Su, Ting-Wei; Ozcan, Aydogan

2010-05-10

173

Lensless wide-field fluorescent imaging on a chip using compressive decoding of sparse objects  

PubMed Central

We demonstrate the use of a compressive sampling algorithm for on-chip fluorescent imaging of sparse objects over an ultra-large field-of-view (>8 cm2) without the need for any lenses or mechanical scanning. In this lensfree imaging technique, fluorescent samples placed on a chip are excited through a prism interface, where the pump light is filtered out by total internal reflection after exciting the entire sample volume. The emitted fluorescent light from the specimen is collected through an on-chip fiber-optic faceplate and is delivered to a wide field-of-view opto-electronic sensor array for lensless recording of fluorescent spots corresponding to the samples. A compressive sampling based optimization algorithm is then used to rapidly reconstruct the sparse distribution of fluorescent sources to achieve ~10 µm spatial resolution over the entire active region of the sensor-array, i.e., over an imaging field-of-view of >8 cm2. Such a wide-field lensless fluorescent imaging platform could especially be significant for high-throughput imaging cytometry, rare cell analysis, as well as for micro-array research.

Coskun, Ahmet F.; Sencan, Ikbal; Su, Ting-Wei; Ozcan, Aydogan

2010-01-01

174

Characterization of High Proper Motion Objects from the Wide-field Infrared Survey Explorer  

NASA Astrophysics Data System (ADS)

We present an analysis of high proper motion objects that we have found in a recent study and in this work with multi-epoch astrometry from the Wide-field Infrared Survey Explorer (WISE). Using photometry and proper motions from the Two Micron All-Sky Survey and WISE, we have identified the members of this sample that are likely to be late-type, nearby, or metal-poor. We have performed optical and near-infrared spectroscopy on 41 objects, from which we measure spectral types that range from M4-T2.5. This sample includes 11 blue L dwarfs and 5 subdwarfs; the latter were also classified as such in the recent study by Kirkpatrick and coworkers. Based on their spectral types and photometry, several of our spectroscopic targets may have distances of <20 pc with the closest at ~12 pc. The tangential velocities implied by the spectrophotometric distances and proper motions indicate that four of the five subdwarfs are probably members of the Galactic halo while several other objects, including the early-T dwarf WISE J210529.08-623558.7, may belong to the thick disk. Based on data from the Wide-field Infrared Survey Explorer, the Two Micron All-Sky Survey, the NASA Infrared Telescope Facility, Gemini Observatory, the SOAR Telescope, and the Magellan Telescopes.

Luhman, K. L.; Sheppard, Scott S.

2014-06-01

175

Objective evaluation of 3-D wide-field effect by human postural control analysis  

NASA Astrophysics Data System (ADS)

A new evaluation method of visual wide-field effects using human postural control analysis is proposed. In designing a television system for future, it is very important to understand the dynamic response of human beings in order to evaluate the visual effects of displayed images objectively. Visual effects produced by 3-D wide-field images are studied. An observer's body sway produced by postural control is discussed using rotating 2-D and 3-D images. Comparisons between stationary and rotating images are also performed. A local peak appears in power spectra of the body sway for the rotating images (3-D and 2-D). On the other hand, no distinctive component appears in the power spectra for the stationary images. By extending the visual field, the cyclic component can be proved from the audio-correlation function of the body sway for the rotating images. These results suggest that displayed images induce the postural control. The total length of the body sway locus is also analyzed to evaluate the postural control. The total length for the rotating images increases in proportion to viewing angles, and is nearly saturated after 50 (deg). Moreover, it is shown that the total length for the rotating 3-D image is greater than for the rotating 2-D image.

Shimizu, Toshihiro; Yano, Sumio; Mitsuhashi, Tetsuo

1992-08-01

176

Treatment strategies for inherited optic neuropathies: past, present and future  

PubMed Central

Bilateral visual loss secondary to inherited optic neuropathies is an important cause of registrable blindness among children and young adults. The two prototypal disorders seen in clinical practice are Leber hereditary optic neuropathy (LHON) and autosomal dominant optic atrophy (DOA). About 90% of LHON cases are due to one of three mitochondrial DNA (mtDNA) point mutations: m.3460G>A, m.11778G>A, and m.14484T>C, which affect critical complex I subunits of the mitochondrial respiratory chain. The majority of patients with DOA harbour pathogenic mutations within OPA1, a nuclear gene that codes for a multifunctional inner mitochondrial membrane protein. Despite their contrasting genetic basis, LHON and DOA share overlapping pathological and clinical features that serve to highlight the striking tissue-specific vulnerability of the retinal ganglion cell (RGC) layer to disturbed mitochondrial function. In addition to severe visual loss secondary to progressive optic nerve degeneration, a subgroup of patients will also develop a more aggressive syndromic phenotype marked by significant neurological deficits. The management of LHON and DOA remains largely supportive, but major advances in our understanding of the mechanisms underpinning RGC loss in these two disorders are paving the way for novel forms of treatment aimed at halting or reversing visual deterioration at different stages of the disease process. In addition to neuroprotective strategies for rescuing RGCs from irreversible cell death, innovative in vitro fertilisation techniques are providing the tantalising prospect of preventing the germline transmission of pathogenic mtDNA mutations, eradicating in so doing the risk of disease in future generations.

Yu-Wai-Man, P; Votruba, M; Moore, A T; Chinnery, P F

2014-01-01

177

Treatment strategies for inherited optic neuropathies: past, present and future.  

PubMed

Bilateral visual loss secondary to inherited optic neuropathies is an important cause of registrable blindness among children and young adults. The two prototypal disorders seen in clinical practice are Leber hereditary optic neuropathy (LHON) and autosomal dominant optic atrophy (DOA). About 90% of LHON cases are due to one of three mitochondrial DNA (mtDNA) point mutations: m.3460G>A, m.11778G>A, and m.14484T>C, which affect critical complex I subunits of the mitochondrial respiratory chain. The majority of patients with DOA harbour pathogenic mutations within OPA1, a nuclear gene that codes for a multifunctional inner mitochondrial membrane protein. Despite their contrasting genetic basis, LHON and DOA share overlapping pathological and clinical features that serve to highlight the striking tissue-specific vulnerability of the retinal ganglion cell (RGC) layer to disturbed mitochondrial function. In addition to severe visual loss secondary to progressive optic nerve degeneration, a subgroup of patients will also develop a more aggressive syndromic phenotype marked by significant neurological deficits. The management of LHON and DOA remains largely supportive, but major advances in our understanding of the mechanisms underpinning RGC loss in these two disorders are paving the way for novel forms of treatment aimed at halting or reversing visual deterioration at different stages of the disease process. In addition to neuroprotective strategies for rescuing RGCs from irreversible cell death, innovative in vitro fertilisation techniques are providing the tantalising prospect of preventing the germline transmission of pathogenic mtDNA mutations, eradicating in so doing the risk of disease in future generations. PMID:24603424

Yu-Wai-Man, P; Votruba, M; Moore, A T; Chinnery, P F

2014-05-01

178

Wide-field astronomy at Dome C with a compact two-mirror, three-reflection telescope  

Microsoft Academic Search

We present a project for a wide-field, compact telescope that has been deisgned for observation in difficult sites, such as in the Antacrtic Plateau. The basic optics is an F\\/3 two-mirror system (2MTRT), in which the primary acts as 1st and 3rd reflecting surface. The Amoretti design provides a corrected and unvignetted 2deg FOV and planarity of the focal plane.

C. D. La Padula; A. Carusi; G. R. Lemaitre; P. Montiel; D. Nanni; G. B. Valsecchi; A. Vignato; R. F. Viotti

2003-01-01

179

Wide-field Functional Imaging of Blood Flow and Hemoglobin Oxygen Saturation in the Rodent Dorsal Window Chamber  

PubMed Central

The rodent dorsal window chamber is a widely used in vivo model of the microvasculature. The model consists of a 1cm region of exposed microvasculature in the rodent dorsal skin that is immobilized by surgically implanted titanium frames, allowing the skin microvasculature to be visualized. We describe a detailed protocol for surgical implantation of the dorsal window chamber which enables researchers to perform the window chamber implantation surgery. We further describe subsequent wide-field functional imaging of the chamber to obtain hemodynamic information in the form of blood oxygenation and blood flow on a cm size region of interest. Optical imaging techniques, such as intravital microscopy, have been applied extensively to the dorsal window chamber to study microvascular-related disease and conditions. Due to the limited field of view of intravital microscopy, detailed hemodynamic information typically is acquired from small regions of interest, typically on the order of hundreds of ?m. The wide-field imaging techniques described herein complement intravital microscopy, allowing researchers to obtain hemodynamic information at both microscopic and macroscopic spatial scales. Compared with intravital microscopy, wide-field functional imaging requires simple instrumentation, is inexpensive, and can give detailed metabolic information over a wide field of view.

Moy, Austin J.; White, Sean M.; Indrawan, Elmer S.; Lotfi, Justin; Nudelman, Matthew J.; Costantini, Samantha J.; Agarwal, Nikita; Jia, Wangcun; Kelly, Kristen M.; Sorg, Brian S.; Choi, Bernard

2011-01-01

180

Water-Immersible MEMS scanning mirror designed for wide-field fast-scanning photoacoustic microscopy  

NASA Astrophysics Data System (ADS)

By offering images with high spatial resolution and unique optical absorption contrast, optical-resolution photoacoustic microscopy (OR-PAM) has gained increasing attention in biomedical research. Recent developments in OR-PAM have improved its imaging speed, but have sacrificed either the detection sensitivity or field of view or both. We have developed a wide-field fast-scanning OR-PAM by using a water-immersible MEMS scanning mirror (MEMS-ORPAM). Made of silicon with a gold coating, the MEMS mirror plate can reflect both optical and acoustic beams. Because it uses an electromagnetic driving force, the whole MEMS scanning system can be submerged in water. In MEMS-ORPAM, the optical and acoustic beams are confocally configured and simultaneously steered, which ensures uniform detection sensitivity. A B-scan imaging speed as high as 400 Hz can be achieved over a 3 mm scanning range. A diffraction-limited lateral resolution of 2.4 ?m in water and a maximum imaging depth of 1.1 mm in soft tissue have been experimentally determined. Using the system, we imaged the flow dynamics of both red blood cells and carbon particles in a mouse ear in vivo. By using Evans blue dye as the contrast agent, we also imaged the flow dynamics of lymphatic vessels in a mouse tail in vivo. The results show that MEMS-OR-PAM could be a powerful tool for studying highly dynamic and time-sensitive biological phenomena.

Yao, Junjie; Huang, Chih-Hsien; Martel, Catherine; Maslov, Konstantin I.; Wang, Lidai; Yang, Joon-Mo; Gao, Liang; Randolph, Gwendalyn; Zou, Jun; Wang, Lihong V.

2013-03-01

181

GRAAL: a seeing enhancer for the NIR wide-field imager Hawk-I  

NASA Astrophysics Data System (ADS)

We describe the design and development status of GRAAL, the Ground-layer adaptive optics assisted by Laser, which will deliver enhanced images to the Hawk-I instrument on the VLT. GRAAL is an adaptive optics module, part of AOF, the Adaptive optics facility, using four Laser- and one natural guide-stars to measure the turbulence, and correcting for it by deforming the adaptive secondary mirror of a Unit telescope in the Paranal observatory. The outstanding feature of GRAAL is the extremely wide field of view correction, over 10 arcmin diameter, with an image enhancement of about 20% in average in K band. When observing GRAAL will provide FWHM better than 0.3" 40% of the time. Besides the Adaptive optics facility deformable mirror and Laser guide stars, the system uses subelectron L3-CCD and a real-time computing platform, SPARTA. GRAAL completed early this year a final design phase shared internally and outsourced for its mechanical part by the Spanish company NTE. It is now in manufacturing, with a first light in the laboratory planned in 2011.

Paufique, J.; Bruton, A.; Glindemann, A.; Jost, A.; Kolb, J.; Jochum, L.; Le Louarn, M.; Kiekebusch, M.; Hubin, N.; Madec, P.-Y.; Conzelmann, R.; Siebenmorgen, R.; Donaldson, R.; Arsenault, R.; Tordo, S.

2010-07-01

182

Hardware results for the Wide-field Infrared Survey Explorer (WISE) telescope and scanner  

NASA Astrophysics Data System (ADS)

On December 14, 2009 NASA launched the Wide-field Infrared Survey Explorer (WISE), a NASA MIDEX mission within the Explorers program that is currently performing an all-sky survey in four infrared bands. L-3 Integrated Optical Systems/SSG designed, built, and tested the telescope, scanner, and aft imaging optical system for WISE under contract to the Space Dynamics Laboratory. Hardware and test results for those subsystems are presented, as well as an on-orbit status of their imaging performance. The WISE payload includes a 40 cm afocal telescope, a scan mirror for back-scan during integration, and an aft optics imager assembly. All modules operate below 17 Kelvin. The allreflective system uses aluminum mirrors and metering structures. The afocal telescope provides distortion control to better than two parts in a thousand to prevent image blur during internal scanning. The one-axis scan mirror at the exit pupil scans the detectors' field-of-view across the telescope field-of-regard, countering the orbital motion and freezing the line of sight during the multi-second exposure period. The five-mirror imaging optics module follows the scan mirror and feeds dichroic beamsplitters that separate the energy into four channels between 2.8 and 26 microns. Once initial on-orbit checkout and calibration was completed, WISE began a 6-month mission performing an all-sky survey in the four infrared bands, which is over 80% complete as of June 2010.

Schwalm, Mark; Akerstrom, Alan; Barry, Mark; Guregian, Jim; Larsen, Mark; Laquidara, Peter; Regan, Jack; Ugolini, Virginia

2010-07-01

183

Signal-to-noise ratio for the wide field-planetary camera of the Space Telescope  

NASA Technical Reports Server (NTRS)

Signal-to-noise ratios for the Wide Field Camera and Planetary Camera of the Space Telescope were calculated as a function of integration time. Models of the optical systems and CCD detector arrays were used with a 27th visual magnitude point source and a 25th visual magnitude per arc-sq. second extended source. A 23rd visual magnitude per arc-sq. second background was assumed. The models predicted signal-to-noise ratios of 10 within 4 hours for the point source centered on a signal pixel. Signal-to-noise ratios approaching 10 are estimated for approximately 0.25 x 0.25 arc-second areas within the extended source after 10 hours integration.

Zissa, D. E.

1984-01-01

184

WISPIR: A Wide-Field Imaging SPectrograph for the InfraRed for the SPICA Observatory  

NASA Technical Reports Server (NTRS)

We have undertaken a study of a far infrared imaging spectrometer based on a Fourier transform spectrometer that uses well-understood, high maturity optics, cryogenics, and detectors to further our knowledge of the chemical and astrophysical evolution of the Universe as it formed planets, stars, and the variety of galaxy morphologies that we observe today. The instrument, Wide-field Imaging Spectrometer for the InfraRed (WISPIR), would operate on the SPICA observatory, and will feature a spectral range from 35 - 210 microns and a spectral resolving power of R=1,000 to 6,000, depending on wavelength. WISPIR provides a choice of full-field spectral imaging over a 2'x2' field or long-slit spectral imaging along a 2' slit for studies of astrophysical structures in the local and high-redshift Universe. WISPIR in long-slit mode will attain a sensitivity two orders of magnitude better than what is currently available.

Benford, Dominic J.; Mundy, Lee G.

2010-01-01

185

Strategy for contamination control to improve Wide-Field/Planetary Camera far-ultraviolet performance  

NASA Technical Reports Server (NTRS)

A multifaceted contamination control strategy has been developed for the second generated Wide-Field and Planetary Camera (WFPC-2) to improve the FUV stability by several orders of magnitude, compared to the first camera (WFPC-1). The strategy involves: improved on-orbit boil-off capability of the detector optics, added internal shielding and instrument venting, in-process subassembly vacuum bakeout at elevated temperatures, material substitution, sample testing in ultraclean vacuum facility, and internal instrument contamination-transport modeling. A science performance goal of 1 percent photometric accuracy at 1470 A over an extended time (of at least 30 days) has been established as a contamination control target for WFPC-2. The WFPC-2 is currently planned to be launched by the Shuttle in mid-1993 and replace the WFPC-1 which was recently launched with the HST.

Leschly, Kim; Taylor, Daniel M.; Jenkins, Teresa; Barengoltz, Jack B.

1990-01-01

186

Sampling and Analysis of Impact Crater Residues Found on the Wide Field Planetary Camera-2 Radiator  

NASA Technical Reports Server (NTRS)

After nearly 16 years in low Earth orbit (LEO), the Wide Field Planetary Camera-2 (WFPC2) was recovered from the Hubble Space Telescope (HST) in May 2009, during the 12 day shuttle mission designated STS-125. The WFPC-2 radiator had been struck by approximately 700 impactors producing crater features 300 microns and larger in size. Following optical inspection in 2009, agreement was reached for joint NASA-ESA study of crater residues, in 2011. Over 480 impact features were extracted at NASA Johnson Space Center's (JSC) Space Exposed Hardware clean-room and curation facility during 2012, and were shared between NASA and ESA. We describe analyses conducted using scanning electron microscopy (SEM) - energy dispersive X-ray spectrometry (EDX): by NASA at JSC's Astromaterials Research and Exploration Science (ARES) Division; and for ESA at the Natural History Museum (NHM), with Ion beam analysis (IBA) using a scanned proton microbeam at the University of Surrey Ion Beam Centre (IBC).

Kearsley, A. T.; Grime, G. W.; Colaux, J. L.; Jeynes, C.; Palitsin, V. V.; Webb, R, P.; Griffin, T. J.; Reed, B. B.; Anz-Meador, P. D.; Kou, J.-C.; Robinson, G. A.; Opiela, J. N.; Gerlach, L.

2013-01-01

187

Characterization of spatially varying aberrations for wide field-of-view microscopy  

PubMed Central

We describe a simple and robust approach for characterizing the spatially varying pupil aberrations of microscopy systems. In our demonstration with a standard microscope, we derive the location-dependent pupil transfer functions by first capturing multiple intensity images at different defocus settings. Next, a generalized pattern search algorithm is applied to recover the complex pupil functions at ~350 different spatial locations over the entire field-of-view. Parameter fitting transforms these pupil functions into accurate 2D aberration maps. We further demonstrate how these aberration maps can be applied in a phase-retrieval based microscopy setup to compensate for spatially varying aberrations and to achieve diffraction-limited performance over the entire field-of-view. We believe that this easy-to-use spatially-varying pupil characterization method may facilitate new optical imaging strategies for a variety of wide field-of-view imaging platforms.

Zheng, Guoan; Ou, Xiaoze; Horstmeyer, Roarke; Yang, Changhuei

2013-01-01

188

Micrometeoroid Impacts on the Hubble Space Telescope Wide Field and Planetary Camera 2: Smaller Particle Impacts  

NASA Technical Reports Server (NTRS)

The radiator shield on the Wide Field and Planetary Camera 2 (WFPC2) was subject to optical inspection following return from the Hubble Space Telescope (HST) in 2009. The survey revealed over 600 impact features of > 300 micrometers diameter, from exposure in space for 16 years. Subsequently, an international collaborative programme of analysis was organized to determine the origin of hypervelocity particles responsible for the damage. Here we describe examples of the numerous smaller micrometeoroid (MM) impact features (< 700 micrometers diameter) which excavated zinc orthotitanate (ZOT) paint from the radiator surface, but did not incorporate material from underlying Al alloy; larger impacts are described by [3]. We discuss recognition and interpretation of impactor remains, and MM compositions found on WFPC2.

Ross, D. K.; Anz-Meador, P.; Liou, J.C.; Opiela, J.; Kearsley, A. T.; Grime, G.; Webb, R.; Jeynes, C.; Palitsin, V.; Colaux, J.; Griffin, T.; Gerlach, L.; Wozniakiewicz, P. J.; Price, M. C.; Burchell, M. J.; Cole, M. J.

2014-01-01

189

Estimated performance of the Wide-field Infrared Explorer (WIRE) instrument  

NASA Astrophysics Data System (ADS)

The Wide-Field IR Explorer (WIRE) is a small spaceborne cryogenic IR telescope being readied for launch in September 1998. Part of NASA's Small Explorer program, WIRE will carry out a deep pointed survey in broad 24 and 12 micron passbands designed primarily to study the evolution of starburst galaxies and to search for protogalaxies. The strategy for the WIRE survey and its stare-and-dither technique for building up long exposure times are described. An overview of the WIRE instrument is presented, with emphasis on the results of ground characterization and expected on-orbit performance of the WIRE optics and the Si:As focal plane arrays. The result of the ground characterization demonstrate that WIRE will meet or exceed the requirements for its science objectives. A brief overview is given of the primary and additional science that will be enabled by WIRE.

Shupe, David L.; Larsen, Mark F.; Sargent, Steven D.; Peterson, James Q.; Tansock, Joseph J.; Luchik, Thomas S.; Hacking, Perry B.; Herter, Terry L.

1998-08-01

190

Wide field aplanatic two-mirror telescopes for ground-based ?-ray astronomy  

NASA Astrophysics Data System (ADS)

Aplanatic telescopes with two aspheric mirrors, configured to correct spherical and coma aberrations, are considered for application in ?-ray astronomy utilizing the ground-based atmospheric Cherenkov technique. We explore the phase space of optical system parameters to find telescope configurations which minmize astigmatism. It is shown that unlike the traditional prime-focus Davies-Cotton design, such telescopes provide a solution for wide field of view ?-ray observations. The designs are isochronous, can be optimized to have no vignetting across the field, and allow for significant reduction of the plate scale, making them compatible with finely-pixilated cameras, which can be constructed from modern, cost-effective image sensors such as multi-anode PMTs, SiPMs, or image intensifiers.

Vassiliev, V.; Fegan, S.; Brousseau, P.

2007-09-01

191

Wide-field-of-view imaging spectrometer (WFIS) engineering model laboratory tests and field demonstrations  

NASA Astrophysics Data System (ADS)

The Wide Field-of View Imaging Spectrometer (WFIS) is a patented optical design allowing horizon to horizon imaging of the earth and earth"s atmosphere in the pushbroom-imaging mode from an aircraft or space platform. The design couples a fast, F/2.8, unobstructed all reflective telescope to an all-reflective three element imaging spectrometer using a unique field coupling mirror arrangement. Early laboratory demonstrations of the technology covered fields of view exceeding 70 degrees. The latest instrument, the incubator WFIS, demonstrate the field of view can be extended to 120 degrees. This paper summarizes the current ongoing work with the engineering model WFIS covering this field of view and a spectral range from 360 nm to 1000 nm. Also presented are the results of the latest laboratory and field demonstrations. The paper also identifies specific applications the technology is now addressing.

Haring, Robert E.; Pollock, Randy; Cross, Richard M.

2003-12-01

192

Wide field of view laser beacon system for three-dimensional aircraft position measurement  

NASA Technical Reports Server (NTRS)

This paper presents a new wide field of view laser beacon system for measurement, in three dimensions, of aircraft or other remote objects. The system is developed for aircraft collision hazard warning independent of ground-based hardware, as well as for flight research, helicopter-assisted construction and rescue, and robotic manipulation applications. Accurate information describing the relative range, elevation, and azimuth of the aircraft are generated by the sweep of a low-power fan-shaped rotating laser beacon past an array of optical detectors. The system achieves a wide angle of acceptance of laser beacon light through use of compound parabolic concentrators, which collimate the light for spectral filtering to minimize solar interference. An on-board microprocessor system converts the pulse sequence to aircraft position in real time. System reliability and performance are enhanced through narrow pass filtering of the pulse signals, digital logic design to mask spurious signals, and adaptive modulation of trigger threshold levels.

Sweet, L. M.; Miles, R. B.; Webb, S. G.; Wong, E. Y.

1981-01-01

193

Quantitative microscopy and nanoscopy of sickle red blood cells performed by wide field digital interferometry  

NASA Astrophysics Data System (ADS)

We have applied wide-field digital interferometry (WFDI) to examine the morphology and dynamics of live red blood cells (RBCs) from individuals who suffer from sickle cell anemia (SCA), a genetic disorder that affects the structure and mechanical properties of RBCs. WFDI is a noncontact, label-free optical microscopy approach that can yield quantitative thickness profiles of RBCs and measurements of their membrane fluctuations at the nanometer scale reflecting their stiffness. We find that RBCs from individuals with SCA are significantly stiffer than those from a healthy control. Moreover, we show that the technique is sensitive enough to distinguish classes of RBCs in SCA, including sickle RBCs with apparently normal morphology, compared to the stiffer crescent-shaped sickle RBCs. We expect that this approach will be useful for diagnosis of SCA and for determining efficacy of therapeutic agents.

Shaked, Natan T.; Satterwhite, Lisa L.; Telen, Marilyn J.; Truskey, George A.; Wax, Adam

2011-03-01

194

Wide Field Infrared Survey Telescope [WFIRST]: telescope design and simulated performance  

NASA Astrophysics Data System (ADS)

The Wide Field Infrared Survey Telescope (WFIRST) mission concept was ranked first in new space astrophysics missions by the Astro2010 Decadal Survey, incorporating the Joint Dark Energy Mission payload concept and multiple science white papers. This mission is based on a space telescope at L2 studying exoplanets [via gravitational microlensing], probing dark energy, and surveying the near infrared sky. Since the release of the Astro2010 Decadal Survey, the team has been working with the WFIRST Science Definition Team to refine mission and payload concepts. We present the current interim reference mission point design of the payload, based on the use of a 1.3m unobscured aperture three mirror anastigmat form, with focal imaging and slit-less spectroscopy science channels. We also present the first results of Structural/Thermal/Optical performance modeling of the telescope point design.

Goullioud, R.; Content, D. A.; Kuan, G. M.; Moore, J. D.; Chang, Z.; Sunada, E. T.; Villalvazo, J.; Hawk, J. P.; Armani, N. V.; Johnson, E. L.; Powell, C. A.

2012-09-01

195

Lessons Learned from the Wide Field Camera 3 TV1 Test Campaign and Correlation Effort  

NASA Technical Reports Server (NTRS)

In January 2004, shortly after the Columbia accident, future servicing missions to the Hubble Space Telescope (HST) were cancelled. In response to this, further work on the Wide Field Camera 3 instrument was ceased. Given the maturity level of the design, a characterization thermal test (TV1) was completed in case the mission was re-instated or an alternate mission found on which to fly the instrument. This thermal test yielded some valuable lessons learned with respect to testing configurations and modeling/correlation practices, including: 1. Ensure that the thermal design can be tested 2. Ensure that the model has sufficient detail for accurate predictions 3. Ensure that the power associated with all active control devices is predicted 4. Avoid unit changes for existing models. This paper documents the difficulties presented when these recommendations were not followed.

Peabody, Hume; Stavley, Richard; Bast, William

2007-01-01

196

Generic Misalignment Aberration Patterns in Wide-Field Telescopes  

Microsoft Academic Search

Aligned telescopes either produce third-order Seidel aberrations or are specifically designed to balance them out. These Seidel aberrations manifest in the field as patterns of point spread functions. When optics are misaligned, breaking the axial symmetry of the telescope, another set of generic third-order aberration patterns arise, one each for coma, astigmatism, and curvature of field, and two for distortion.

Rebecca Sobel; P. L. Schechter

2011-01-01

197

HARP-B and Wide-Field Imaging of Molecular Clouds  

NASA Astrophysics Data System (ADS)

Molecular clouds within our galaxy provide excellent opportunities to study the processes of star formation in detail. They extend over large regions of the sky, and therefore wide-field imaging is required to capture all of the structure inside them, and to investigate their varied conditions. Performing this task efficiently, in high resolution, and over statistically useful numbers of clouds can best be achieved using array receivers. However these are a relatively new development due to the difficulty of constructing instrumentation for the millimetre and sub-millimetre wavelengths at which molecular clouds emit. Part I of this thesis describes HARP-B - a new heterodyne array receiver operating at 345GHz on the James Clerk Maxwell Telescope. The work described focusses on the optics, interferometer and commissioning of HARP-B. Careful testing and alignment of the optics was necessary to ensure that HARP-B would perform as required. Its Mach-Zehnder interferometer was put under computer control and characterised to allow it to be used as an effective sideband filter. This part concludes with the integration and commissioning of the receiver, leading up to first light. Part II then presents wide-field observations of the IC5146 and L977 molecular clouds, made with HARP-B and other instruments at the JCMT and IRAM 30m telescopes. For IC5146, SCUBA continuum images and a dust extinction map were already available. These were complemented by spectral observations of C18O 1-0, C18O 2-1 and the 3-2 transition of 12CO, 13CO and C18O. The data were used to study the cloud structure, excitation conditions and dust properties. SCUBA continuum and C18O 2-1 observations were made of L977 and analysed along with the existing dust extinction map in order to study the dust and gas properties, and the structure of the molecular cloud.

Bell, Graham S.

2008-10-01

198

Future electro-optical sensors and processing in urban operations  

NASA Astrophysics Data System (ADS)

In the electro-optical sensors and processing in urban operations (ESUO) study we pave the way for the European Defence Agency (EDA) group of Electro-Optics experts (IAP03) for a common understanding of the optimal distribution of processing functions between the different platforms. Combinations of local, distributed and centralized processing are proposed. In this way one can match processing functionality to the required power, and available communication systems data rates, to obtain the desired reaction times. In the study, three priority scenarios were defined. For these scenarios, present-day and future sensors and signal processing technologies were studied. The priority scenarios were camp protection, patrol and house search. A method for analyzing information quality in single and multi-sensor systems has been applied. A method for estimating reaction times for transmission of data through the chain of command has been proposed and used. These methods are documented and can be used to modify scenarios, or be applied to other scenarios. Present day data processing is organized mainly locally. Very limited exchange of information with other platforms is present; this is performed mainly at a high information level. Main issues that arose from the analysis of present-day systems and methodology are the slow reaction time due to the limited field of view of present-day sensors and the lack of robust automated processing. Efficient handover schemes between wide and narrow field of view sensors may however reduce the delay times. The main effort in the study was in forecasting the signal processing of EO-sensors in the next ten to twenty years. Distributed processing is proposed between hand-held and vehicle based sensors. This can be accompanied by cloud processing on board several vehicles. Additionally, to perform sensor fusion on sensor data originating from different platforms, and making full use of UAV imagery, a combination of distributed and centralized processing is essential. There is a central role for sensor fusion of heterogeneous sensors in future processing. The changes that occur in the urban operations of the future due to the application of these new technologies will be the improved quality of information, with shorter reaction time, and with lower operator load.

Grönwall, Christina; Schwering, Piet B.; Rantakokko, Jouni; Benoist, Koen W.; Kemp, Rob A. W.; Steinvall, Ove; Letalick, Dietmar; Björkert, Stefan

2013-10-01

199

Integral wide-field spectroscopy in astronomy: the Imaging FTS solution  

NASA Astrophysics Data System (ADS)

Long-slit grating spectrometers in scanning mode and Fabry-Perot interferometers as tunable filters are commonly used to perform integral wide-field spectroscopy on extended astrophysical objects as HII regions and nearby galaxies. The goal of this paper is to demonstrate, by comparison, through a thorough review of the imaging Fourier transform spectrometer (IFTS) properties, that this instrument represents another interesting solution. After a brief recall of the performances, regarding FOV and spectral resolution, of the grating spectrometer, without and with integral field units (IFU), and of the imaging Fabry-Perot, it is demonstrated that for an IFTS the product of the maximum resolution R by the entrance beam étendue U is equal to 2.6 N× S_I with N × N the number of pixels of the detector array and S_I the area of the interferometer beamsplitter. As a consequence, the IFTS offers the most flexible choice of field size and spectral resolution, up to high values for both parameters. It also presents on a wide field an important multichannel advantage in comparison to integral field grating spectrometers, even with multiple IFUs. To complete, the few astronomical IFTSs, built behind ground-based telescopes and in space, for the visible range up to the sub-millimetric domain, are presented. Through two wide-field IFTS projects, one in the visible, the other one in the mid-infrared, the question is addressed of the practical FOV and resolution limits, set by the optical design of the instrument, which can be achieved. Within the 0.3 to ˜ 2.5 \\upmum domain, a Michelson interferometer with wide-field diopric collimators provides the easiest solution. This design is illustrated by a 11^'× 11^'-field IFTS in the 0.35-0.90 \\upmum range around an off-axis interferometer, called SITELLE, proposed for the 3.6-m CFH Telescope. At longer wavelengths, an all-mirror optics is required, as studied for a spaceborne IFTS, H2EX, for the 8-29 \\upmum range, a 20^' × 20^' field, and a high resolution of ˜eq 3× 10^4 at 10 \\upmum. To comply with these characteristics, the interferometer is designed with cat's eye retroreflectors. In the same domain and up to the far infrared, if the instrument aims only at a low spectral resolution (few thousands) and a smaller field (few arcmins^2), roof-top or corner cube mirrors, as for the IFTS SPIRE on the Herschel space telescope, are usable. At last, perspectives are opened, behind an ELT in the visible and the near infrared with the SITELLE optical combination, in the 2-5 \\upmum on the Antarctic plateau or in space up to longer wavelengths, with the H2EX design, to provide the missing capability of global high spectral resolution studies of extended sources, from comets to distant galaxy clusters.

Maillard, J. P.; Drissen, L.; Grandmont, F.; Thibault, S.

2013-04-01

200

Alignment of four-mirror wide field corrector for the Hobby-Eberly Telescope  

NASA Astrophysics Data System (ADS)

The Hobby-Eberly Telescope (HET) Wide Field Corrector (WFC) is a four-mirror optical system which corrects for aberrations from the 10-m segmented spherical primary mirror. The WFC mirror alignments must meet particularly tight tolerances for the system to meet performance requirements. The system uses 1-m class highly aspheric mirrors, which precludes conventional alignment methods. For the WFC system alignment a "center reference fixture" has been used as the reference for each mirror's vertex and optical axis. The center reference fixtures have both a CGH and sphere mounted retroreflector (SMR) nests. The CGH is aligned to the mirror's optical axis to provide a reference for mirror decenter and tilt. The vertex of each mirror is registered to the SMR nests on the center reference fixtures using a laser tracker. The spacing between the mirror vertices is measured during the system alignment using these SMR nest locations to determine the vertex locations. In this paper we present the procedures and results from creating and characterizing these center reference fixtures. As a verification of our alignment methods we also present results from their application in the WFC system alignment are also presented.

Oh, Chang Jin; Frater, Eric H.; Coyle, Laura; Dubin, Matt; Lowman, Andrew; Zhao, Chunyu; Burge, James H.

2013-09-01

201

Wide-field high-performance geosynchronous imaging  

NASA Astrophysics Data System (ADS)

The NASA Mission to Planet Earth (MTPE) Program and the National Oceanographic and Atmospheric Administration (NOAA) are sponsoring the Advanced Geosynchronous Studies (AGS) to develop technologies and system concepts for Earth observation from geosynchronous orbit. This series of studies is intended to benefit both MTPE science and the NOAA GOES Program. Within the AGS program, advanced imager trade studies have investigated two candidate concepts for near-term advanced geosynchronous imagers. One concept uses a scan mirror to direct the line of sight from a 3-axis stabilized platform. Another eliminates the need for a scan mirror by using an agile spacecraft bus to scan the entire instrument. The purpose of this paper is to discuss the optical design trades and system issues encountered in evaluating the two scanning approaches. The imager design started with a look at first principles: what is the most efficient way to image the Earth in those numerous spectral bands of interest to MTPE scientists and NOAA weather forecasters. Optical design trades included rotating filter wheels and dispersive grating instruments. The design converged on a bandpass filter instrument using four focal planes to cover the spectral range 0.45 to 13.0 micrometers. The first imager design uses a small agile spacecraft supporting an afocal optical telescope. Dichroic beamsplitters feed refractive objectives to four focal planes. The detectors are a series of long linear and rectangular arrays which are scanned in a raster fashion over the 17 degree Earth image. The use of the spacecraft attitude control system to raster the imager field-of-view (FOV) back and forth over the Earth eliminates the need for a scan mirror. However, the price paid is significant energy and time required to reverse the spacecraft slew motions at the end of each scan line. Hence, it is desired to minimize the number of scan lines needed to cover the full Earth disk. This desire, coupled with the ground coverage requirements, drives the telescope design to a 1.6 degree square FOV to provide full Earth disk coverage in less than 12 swaths. The telescope design to accommodate the FOV and image quality requirements is a 30 cm aperture three-element off-axis anastigmat. The size and mass of the imager instrument that result from this optical configuration are larger than desired. But spacecraft reaction wheel torque and power requirements to raster the imager FOV are achievable using existing spacecraft technology. However, launch mass and cost are higher than desired. In the second high-level trade study, the AGS imager team is looking at incorporating a scan mirror and having the satellite three-axis stabilized. The use of the scan mirror eliminates the long turn-around times of the spacecraft scanning approach, allowing for faster Earth coverage. Thus the field of view of the afocal telescope can be reduced by half while still satisfying ground coverage requirements. The optical design of the reduced field afocal telescope is being studied to shrink its size and improve its performance. Both a three-mirror Cassegrain afocal and a two-mirror pair of confocal paraboloids are being considered. With either telescope, the size, mass, and power requirements of this imager are significantly less than those of the first imager design. Both imager designs appear to be feasible and both meet envisioned MTPE and NOAA geosynchronous imaging needs. The AGS imager team is continuing to explore the optical trade space to further optimize imager designs.

Wood, H. John; Jenstrom, Del; Wilson, Mark; Hinkal, Sanford; Kirchman, Frank

1998-01-01

202

High-Resolution, Wide-Field-of-View Scanning Telescope  

NASA Technical Reports Server (NTRS)

A proposed telescope would afford high resolution over a narrow field of view (<0.10 ) while scanning over a total field of view nominally 16 wide without need to slew the entire massive telescope structure. The telescope design enables resolution of a 1-m-wide object in a 50- km-wide area of the surface of the Earth as part of a 200-km-wide area field of view monitored from an orbit at an altitude of 700 km. The conceptual design of this telescope could also be adapted to other applications both terrestrial and extraterrestrial in which there are requirements for telescopes that afford both wide- and narrow-field capabilities. In the proposed telescope, the scanning would be effected according to a principle similar to that of the Arecibo radio telescope, in which the primary mirror is stationary with respect to the ground and a receiver is moved across the focal surface of the primary mirror. The proposed telescope would comprise (1) a large spherical primary mirror that would afford high resolution over a narrow field of view and (2) a small displaceable optical relay segment that would be pivoted about the center of an aperture stop to effect the required scanning (see figure). Taken together, both comprise a scanning narrow-angle telescope that does not require slewing the telescope structure. In normal operation, the massive telescope structure would stare at a fixed location on the ground. The inner moveable relay optic would be pivoted to scan the narrower field of view over the wider one, making it possible to retain a fixed telescope orientation, while obtaining high-resolution images over multiple target areas during an interval of 3 to 4 minutes in the intended orbit. The pivoting relay segment of the narrow-angle telescope would include refractive and reflective optical elements, including two aspherical mirrors, to counteract the spherical aberration of the primary mirror. Overall, the combination of the primary mirror and the smaller relay optic would provide narrow-angle, diffraction-limited high resolution at a wavelength of 500 nm.

Sepulveda, Cesar; Wilson, Robert; Seshadri, Suresh

2007-01-01

203

Large filters for wide-field survey telescope LSST  

NASA Astrophysics Data System (ADS)

The LSST design foresees the use of six wide-band large optical filters that can alternatively be moved in front of the CCD camera. Each of the six filters has a different band-pass covering all the wavelengths from 300 nm to 1200 nm. The way to achieve this is to coat an optimized optical thin films stack on a filter substrate. Each filter requires a specific design using specific appropriate materials. The main characteristics of these filters, that constitute a real technological challenge, are: their relatively large size - their radii of curvature (about 5.6 m) that represent a sagitta of 12,5 mm that increases the uniformity complexity, the large rejection band requirements with transmission lower than 0.01 % out of the band and a transmission of 95 % over the band-pass. This paper proposes to show the problematic and the results obtained at LMA (Laboratoire des Matériaux Avancés-FRANCE) to the purpose of realizing these filters using the IBS (Ion Beam Sputtering) deposition technique. The results obtained with High-Pass/Low-Pass structures will be presented. Experimental results will be shown concerning the R-band filter (552-691 nm). An overview of the work to be done to realize transmittance map over large filters will be given.

Morgado, Nazario; Pinard, Laurent; Sassolas, Benoit; Flaminio, Raffaele; Forest, Daniéle; Lagrange, Bernard; Michel, Christophe; Antilogus, Pierre

2012-09-01

204

Recent Advances in Low-Radio-Frequency Wide-Field Imaging  

NASA Astrophysics Data System (ADS)

Recent exciting advances in wide-field imaging of low-frequency radio interferometry data have had significant scientific impact on a number of important astrophysical problems. Thermal-noise or confusion-limited images from 330 MHz or 74 MHz data taken with the Very Large Array (VLA) often resemble optical photographs in appearance. Fields as large as 8 degrees on a side may be obtained at a single pointing. Routine use of these data has been limited by the computational burden of properly imaging the fields at full resolution. The low-frequency radio sky is filled with sources and one must image the whole primary beam or more to remove the effect of confusing sources. Also, the usual two-dimensional approximation used in Fourier-synthesis imaging breaks down on these wide fields. The program dragon exists for the solution of the wide-field problem but is very slow. In the common ``contiguous faceting'' mode of operation, it completely tessellates the curved sky with small tangent planes. We have ported dragon to the parallel architecture SGI Power Challenge Array and can now produce VLA B-configuration images in a few hours. For high-resolution A-configuration images, still extremely computationally challenging, we have implemented a ``targeted faceting'' approach to sidelobe removal. A low-resolution image is constructed and used to automatically tabulate all sources in the primary beam. A large but tractable region of the sky is tessellated with normal contiguous facets, and the remaining sources are addressed with small targeted facets centered on each region of emission. Treatment of outlying sources is similar to the NRAO program MX, but a complete deconvolution to thermal noise may require 200 to 800 targeted facets instead of a few. The resulting high-resolution image may be a degree or more in size, while still reducing the computational load by an order of magnitude. Full-resolution images of the supernova remnant/HII complex W49 will be shown to illustrate the power of this method.

Briggs, D. S.; Kassim, N. E.; Foster, R. S.

1996-12-01

205

Wide-Field High-Performance Geosynchronous Imaging  

NASA Technical Reports Server (NTRS)

The NASA Mission to Planet Earth (MTPE) Program and the National Oceanographic and Atmospheric Administration (NOAA) are sponsoring the Advanced Geosynchronous Studies (AGS) to develop technologies and system concepts for Earth observation from geosynchronous orbit. This series of studies is intended to benefit both MTPE science and the NOAA GOES Program. Within the AGS program, advanced imager trade studies have investigated two candidate concepts for near-term advanced geosynchronous imagers. One concept uses a scan mirror to direct the line of sight from a 3-axis stabilized platform. Another eliminates the need for a scan mirror by using an agile spacecraft bus to scan the entire instrument. The purpose of this paper is to discuss the optical design trades and system issues encountered in evaluating the two scanning approaches.

Wood, H. John; Jenstrom, Del; Wilson, Mark; Hinkal, Sanford; Kirchman, Frank

1997-01-01

206

Low noise CCD cameras for wide field astronomy  

NASA Astrophysics Data System (ADS)

Modern research trends require observation of fainter and fainter astronomical objects on large areas of the sky. This implies usage of systems with high temporal and optical resolution with computer based data acquisition and processing. Therefore Charge Coupled Devices became so popular. They offer quick picture conversion with much better quality than film based technologies. There are two main trends in astronomical observations. First one is construction of large telescopes with sensitive picture sensors. They allow further exploration of the Universe. An example is the KECK telescope in Hawaii. The other trend is presented by systems that perform observation of large areas of the sky with high resolution in time. They are used to investigate objects, which rapidly change their position or intensity. They are often quite bright, thus the sensitivity of such measurement systems is not so critical. Because of huge amount of data from detector, the analysis must be performed on-line. This way, there is a large reduction of data that are archived and processed later. The example of project that realizes the concept of variable sky objects observation is "Pi of The Sky". The main field of interest is detection of optical flashes that accompany star's explosions. The conditions that are present during such an events are similar to ones that had place in the young Universe. That's why this research is interesting also for particle physics. This work is theoretical and practical study of the CCD based picture acquisition system. This system was optimized for "Pi of The Sky" project. But it can be adapted to another professional astronomical researches. The work includes issue of picture conversion, signal acquisition, data transfer and mechanical construction of the device.

Kasprowicz, Grzegorz

2005-09-01

207

Enabling technologies for future all-optical packet switched networks  

Microsoft Academic Search

This paper addresses the challenges hindering all-optical packet switched networks and it focuses on the technologies that will make it possible. The basic structure of an optical packet switching router is presented. On the basis of the design, the need for optical buffers is justified and the adequacy of optical labels to perform routing is defended. Subsequently, the principles and

Andrea Blanco Redondo; Pablo Beltrán Pellicer; Joseba A. Zubía Zaballa

2009-01-01

208

Retinal optical coherence tomography: past, present and future perspectives.  

PubMed

Optical coherence tomography (OCT) has undergone substantial changes since its first use in the 1990s. Although the first generation of OCT systems heralded a new era in the non-invasive diagnostic options in ophthalmology, they did not reveal much detail. Later devices offered more information and helped in the diagnosis and treatment of a variety of pathological conditions, primarily of the retina. With today's spectral-domain type models ophthalmologists are offered a comprehensive tool with the opportunity for early diagnosis and precise monitoring of patients with retinal and glaucomatous pathologies. However, as experience with these new devices grows and demands by clinicians and researchers rise, further improvements need to be addressed. Future developments in the improvement of the transverse resolution and extension of the penetration depth are to be expected. New modalities such as polarisation sensitive OCT (PS-OCT) or Doppler OCT are now in use and promise additional insights in the properties of physiological and pathological tissue. While PS-OCT reveals further detail in alterations of the retinal pigment epithelium, Doppler OCT gives additional information about blood flow measurements. With these and further new developments, OCT will continue to be an invaluable instrument in the armamentarium of modern ophthalmology. PMID:20675732

Geitzenauer, Wolfgang; Hitzenberger, Christoph K; Schmidt-Erfurth, Ursula M

2011-02-01

209

Wide-field weak lensing by RXJ1347-1145  

NASA Astrophysics Data System (ADS)

We present an analysis of weak lensing observations for RXJ1347--1145 over a 43 ' × 43 ' field taken in B and R filters on the Blanco 4m telescope at CTIO. RXJ1347--1145 is a massive cluster at redshift z=0.45. Using a population of galaxies with 20optical velocity dispersion measurements by Cohen and Kneib, 2002.

Kling, Thomas P.; dell'Antonio, Ian; Wittman, David; Tyson, J. Anthony

2004-05-01

210

Optomechanical design of the Incubator Wide Field of View Imaging Spectrometer  

NASA Astrophysics Data System (ADS)

The optomechanical design of the Wide Field of View Imaging Spectrometer (WFIS) is presented. Developed under NASA's Instrument Incubator Program, the Incubator WFIS is a hyperspectral-imaging spectrometer covering a 120 degree(s) x .015 degree(s) field of view over a 360 nm to 1000 nm spectral range. The Incubator's mission is to demonstrate, via flight aboard NASA's DC-8 Research Aircraft, new technology for earth science. The Incubator WFIS is designed specifically for observing the earth and earth's atmosphere for chemistry and aerosol studies. The optomechanical design couples an off-axis F/3 Schwarzchild telescope to a three element Offner Spectrometer using two unique anamorphic/aspheric field elements. The complete sensor, including a CCD detector and electronics, occupies a volume of approximately cubic shape measuring 25 cm on an edge. An off-axis optical system such as the incubator WFIS requires a multidisciplinary design approach. This paper emphasized the importance that systems approach plays in optomechanical design. This is typified by the trades performed to establish the optimum design alternative for the optical metering structure to achieve the 0.010 nm wavelength stability (with a .005 nm goal) needed for the science mission.

Haring, Robert E.; Vanstone, Gary C.; Nguyen, Frank; Rodil, Cesar A.

2000-10-01

211

A testbed for wide-field, high-resolution, gigapixel-class cameras.  

PubMed

The high resolution and wide field of view (FOV) of the AWARE (Advanced Wide FOV Architectures for Image Reconstruction and Exploitation) gigapixel class cameras present new challenges in calibration, mechanical testing, and optical performance evaluation. The AWARE system integrates an array of micro-cameras in a multiscale design to achieve gigapixel sampling at video rates. Alignment and optical testing of the micro-cameras is vital in compositing engines, which require pixel-level accurate mappings over the entire array of cameras. A testbed has been developed to automatically calibrate and measure the optical performance of the entire camera array. This testbed utilizes translation and rotation stages to project a ray into any micro-camera of the AWARE system. A spatial light modulator is projected through a telescope to form an arbitrary object space pattern at infinity. This collimated source is then reflected by an elevation stage mirror for pointing through the aperture of the objective into the micro-optics and eventually the detector of the micro-camera. Different targets can be projected with the spatial light modulator for measuring the modulation transfer function (MTF) of the system, fiducials in the overlap regions for registration and compositing, distortion mapping, illumination profiles, thermal stability, and focus calibration. The mathematics of the testbed mechanics are derived for finding the positions of the stages to achieve a particular incident angle into the camera, along with calibration steps for alignment of the camera and testbed coordinate axes. Measurement results for the AWARE-2 gigapixel camera are presented for MTF, focus calibration, illumination profile, fiducial mapping across the micro-camera for registration and distortion correction, thermal stability, and alignment of the camera on the testbed. PMID:23742532

Kittle, David S; Marks, Daniel L; Son, Hui S; Kim, Jungsang; Brady, David J

2013-05-01

212

Optical Tecnology Developments in Biomedicine: History, Current and Future  

PubMed Central

Biomedical optics is a rapidly emerging field for medical imaging and diagnostics. This paper reviews several biomedical optical technologies that have been developed and translated for either clinical or pre-clinical applications. Specifically, we focus on the following technologies: 1) near-infrared spectroscopy and tomography, 2) optical coherence tomography, 3) fluorescence spectroscopy and imaging, and 4) optical molecular imaging. There representative biomedical applications are also discussed here.

Nioka, Shoko; Chen, Yu

2011-01-01

213

Status of the GRAAL system development: very wide-field correction with 4 laser guide-stars  

NASA Astrophysics Data System (ADS)

We recall the design and present the development status of GRAAL, the Ground-layer adaptive optics assisted by Laser, which will deliver wide-field (10 arcmin), enhanced images to the HAWK-I instrument on the VLT, with an improved seeing. GRAAL is an adaptive optics module, part of the Adaptive optics facility (AOF), using four Laser- and one natural guide-stars to measure the turbulence, and correcting for it by deforming the adaptive secondary mirror of a Unit telescope in the Paranal observatory. GRAAL is in the laboratory in Europe and the integration of its laser guide-star optics is completed. The first wave-front sensor camera will be ready for its integration in the coming weeks, allowing the first system tests to start.

Paufique, J.; Argomedo, J.; Arsenault, R.; Conzelmann, R.; Donaldson, R.; Hubin, N.; Jochum, L.; Jost, A.; Kiekebusch, M.; Kolb, J.; Kuntschner, H.; Le Louarn, M.; Madec, P.-Y.; Siebenmorgen, R.; Tordo, S.

2012-07-01

214

Exploitation of optical interconnects in future server architectures  

Microsoft Academic Search

Optical fiber links have become ubiquitous for links at the metropolitan and wide area distance scales, and have become common alternatives to electrical links in local area networks and cluster networks. As optical technology improves and link frequencies continue to increase, optical links will be increasingly considered for shorter, higher-bandwidth links such as I\\/O, memory, and system bus links. For

Alan F. Benner; Michael Ignatowski; Jeffrey A. Kash; Daniel M. Kuchta; Mark B. Ritter

2005-01-01

215

Future generation military avionics fiber optics photonics packaging challenges  

Microsoft Academic Search

The military\\/aerospace platform operational environment challenges the creativity of fiber optic module packaging engineers as they endeavor to develop and mature new active and passive single-mode fiber optic and photonic components for next generation avionics networking applications. Low sales and manufacturing volumes inherent to avionics combined with lack of standard interface specifications for current and next generation fiber optic local

Mark W. Beranek

2007-01-01

216

OP09O-OP404-9 Wide Field Camera 3 CCD Quantum Efficiency Hysteresis  

NASA Technical Reports Server (NTRS)

The HST/Wide Field Camera (WFC) 3 UV/visible channel CCD detectors have exhibited an unanticipated quantum efficiency hysteresis (QEH) behavior. At the nominal operating temperature of -83C, the QEH feature contrast was typically 0.1-0.2% or less. The behavior was replicated using flight spare detectors. A visible light flat-field (540nm) with a several times full-well signal level can pin the detectors at both optical (600nm) and near-UV (230nm) wavelengths, suppressing the QEH behavior. We are characterizing the timescale for the detectors to become unpinned and developing a protocol for flashing the WFC3 CCDs with the instrument's internal calibration system in flight. The HST/Wide Field Camera 3 UV/visible channel CCD detectors have exhibited an unanticipated quantum efficiency hysteresis (QEH) behavior. The first observed manifestation of QEH was the presence in a small percentage of flat-field images of a bowtie-shaped contrast that spanned the width of each chip. At the nominal operating temperature of -83C, the contrast observed for this feature was typically 0.1-0.2% or less, though at warmer temperatures contrasts up to 5% (at -50C) have been observed. The bowtie morphology was replicated using flight spare detectors in tests at the GSFC Detector Characterization Laboratory by power cycling the detector while cold. Continued investigation revealed that a clearly-related global QE suppression at the approximately 5% level can be produced by cooling the detector in the dark; subsequent flat-field exposures at a constant illumination show asymptotically increasing response. This QE "pinning" can be achieved with a single high signal flat-field or a series of lower signal flats; a visible light (500-580nm) flat-field with a signal level of several hundred thousand electrons per pixel is sufficient for QE pinning at both optical (600nm) and near-UV (230nm) wavelengths. We are characterizing the timescale for the detectors to become unpinned and developing a protocol for flashing the WFC3 CCDs with the instrument's internal calibration system in flight. A preliminary estimate of the decay timescale for one detector is that a drop of 0.1-0.2% occurs over a ten day period, indicating that relatively infrequent cal lamp exposures can mitigate the behavior to extremely low levels.

Collins, Nick

2009-01-01

217

A mid-infrared study of RR Lyrae stars with the Wide-field Infrared Survey Explorer all-sky data release  

NASA Astrophysics Data System (ADS)

We present a group of 3740 previously identified RR Lyrae variables well observed with the Wide-field Infrared Survey Explorer (WISE). We explore how the shape of the generic RR Lyrae mid-infrared light curve varies over period-space, comparing light curves in mid-infrared and optical bands. We find that optical light curves exhibit high amplitudes and a large spectrum of light-curve shapes, while mid-infrared light curves have low amplitudes and uniform light-curve shapes. From the period-space analysis, we hope to improve the classification methods of RR Lyrae variables and enable reliable discovery of these pulsators in the WISE catalogue and future mid-infrared surveys such as the James Webb Space Telescope. We provide mid-infrared templates for typical RR Lyrae stars and demonstrate how these templates can be applied to improve estimates of mid-infrared RR Lyrae mean magnitude, which is used for distance measurement. This method of template fitting is particularly beneficial for improving observational efficiency. For example, using light curves with observational noise of 0.05 mag, we obtain the same level of accuracy in mean magnitude estimates for light curves randomly sampled at 12 data points with template fitting as with light curves randomly sampled at 20 data points with harmonic modelling.

Gavrilchenko, Tatyana; Klein, Christopher R.; Bloom, Joshua S.; Richards, Joseph W.

2014-06-01

218

Brca1\\/p53 deficient mouse breast tumor hemodynamics during hyperoxic respiratory challenge monitored by a novel wide-field functional imaging (WiFI) system  

Microsoft Academic Search

Current imaging modalities allow precise visualization of tumors but do not enable quantitative characterization of the tumor metabolic state. Such quantitative information would enhance our understanding of tumor progression and response to treatment, and to our overall understanding of tumor biology. To address this problem, we have developed a wide-field functional imaging (WiFI) instrument which combines two optical imaging modalities,

Austin Moy; Jae G. Kim; Eva Y. H. P. Lee; Bruce Tromberg; Albert Cerussi; Bernard Choi

2009-01-01

219

Miniature wide field-of-view star trackers for spacecraft attitude sensing and navigation  

NASA Technical Reports Server (NTRS)

Introducing a family of miniature, wide field-of-view star trackers for low cost, high performance spacecraft attitude determination and navigation applications. These devices, derivative of the WFOV Star Tracker Camera developed cooperatively by OCA Applied Optics and the Lawrence Livermore National Laboratory for the Brilliant Pebbles program, offer a suite of options addressing a wide range of spacecraft attitude measurement and control requirements. These sensors employ much wider fields than are customary (ranging between 20 and 60 degrees) to assure enough bright stars for quick and accurate attitude determinations without long integration intervals. The key benefit of this approach are light weight, low power, reduced data processing loads and high information carrier rates for wide ACS bandwidths. Devices described range from the proven OCA/LLNL WFOV Star Tracker Camera (a low-cost, space-qualified star-field imager utilizing the spacecraft's own computer and centroiding and position-finding), to a new autonomous subsystem design featuring dual-redundant cameras and completely self-contained star-field data processing with output quaternion solutions accurate to 100 micro-rad, 3 sigma, for stand-alone applications.

Mccarty, William; Curtis, Eric; Hull, Anthony; Morgan, William

1993-01-01

220

Telescope Fabra ROA Montsec: A New Robotic Wide Field Baker-Nunn Facility  

NASA Astrophysics Data System (ADS)

A Baker-Nunn Camera (BNC), originally installed at the Real Instituto y Observatorio de la Armada (ROA) in 1958, was refurbished and robotized. The new facility, called Telescope Fabra ROA Montsec (TFRM), was installed at the Observatori Astronòmic del Montsec (OAdM). The process of refurbishment is described in detail. Most of the steps of the refurbishment project were accomplished by purchasing commercial components, which involve little posterior engineering assembling work. The TFRM is a 0.5 m aperture f/0.96 optically modified BNC, which offers a unique combination of instrumental specifications: fully robotic and remote operation, wide field of view (4°.4×4°.40), moderate limiting magnitude (V˜19.5 mag), ability of tracking at arbitrary right ascension (?) and declination (?) rates, as well as opening and closing CCD shutter at will during an exposure. Nearly all kinds of image survey programs can benefit from those specifications. Apart from other less time-consuming programs, since the beginning of science TFRM operations we have been conducting two specific and distinct surveys: super-Earths transiting around M-type dwarfs stars, and geostationary debris in the context of Space Situational Awareness/Space Surveillance and Tracking (SSA/SST) programs. Preliminary results for both cases will be shown.

Fors, Octavi; Núñez, Jorge; Luis Muiños, José; Javier Montojo, Francisco; Baena-Gallé, Roberto; Boloix, Jaime; Morcillo, Ricardo; Teresa Merino, María; Downey, Elwood C.; Mazur, Michael J.

2013-05-01

221

Wide field-of-view Talbot grid-based microscopy for multicolor fluorescence imaging  

PubMed Central

The capability to perform multicolor, wide field-of-view (FOV) fluorescence microscopy imaging is important in screening and pathology applications. We developed a microscopic slide-imaging system that can achieve multicolor, wide FOV, fluorescence imaging based on the Talbot effect. In this system, a light-spot grid generated by the Talbot effect illuminates the sample. By tilting the excitation beam, the Talbot-focused spot scans across the sample. The images are reconstructed by collecting the fluorescence emissions that correspond to each focused spot with a relay optics arrangement. The prototype system achieved an FOV of 12 × 10 mm2 at an acquisition time as fast as 23 s for one fluorescence channel. The resolution is fundamentally limited by spot size, with a demonstrated full-width at half-maximum spot diameter of 1.2 ?m. The prototype was used to image green fluorescent beads, double-stained human breast cancer SK-BR-3 cells, Giardia lamblia cysts, and the Cryptosporidium parvum oocysts. This imaging method is scalable and simple for implementation of high-speed wide FOV fluorescence microscopy.

Pang, Shuo; Han, Chao; Erath, Jessey; Rodriguez, Ana; Yang, Changhuei

2013-01-01

222

[A wide-field push-broom hyperspectral imager based on curved prism].  

PubMed

A wide-field pushbroom hyperspectral imager covering short-wavelength infrared range is presented, which can be carried by space borne or airborne platform for remote sensing, acquiring hyperspectral data cube, and analyzing substance compositions and physicochemical properties. Curved prism which simultaneously possesses the functions of dispersion and imaging is used as the prismatic element, and the combination with Offner relay configuration substantially simplifies the design of spectrometer. Compared to conventional dispersive spectral imagers, this design is compact, light-weighted, and small-sized, and can efficiently correct unavoidable spectral line curve (smile) and spectral band (keystone or frown) by prismatic dispersion Compared to grating spectral imagers of the same configuration, the energy utilization efficiency of this design is much higher. The paraxial aberration theory and imaging characteristics of Offner relay configuration is briefly described. The optical layout and image evaluations, including spatial and spectral dimensions, are illustrated respectively, according to Monte Carlo ray-tracing results of seven principal wavelengths. PMID:22870671

Nie, Yun-Feng; Xiangli, Bin; Zhou, Jin-Song; Huang, Min

2012-06-01

223

Wide-field deep-UV wafer stepper for 0.35-micron production  

NASA Astrophysics Data System (ADS)

Device manufacturers and lithographic equipment makers are presently preparing for circuit production at design rules of 0.35 micrometers . It is evident that optical steppers will be the production tools, but the choice between i-line and deep UV (DUV) steppers (248 nm) is still a matter of debate. This paper reports the progress made in the development of DUV steppers for production purposes. As a successor to the earlier DUV machine, discussed at the SPIE conference in 1990, which uses a TTL alignment system and automatic excimer laser wavelength control, a new DUV stepper has recently been developed with a new lens at 248 nm wavelength, a 29.7 mm diameter field and a numerical aperture (NA) of 0.5. The stepper body is similar to that of the wide field, i-line systems which have been in production since 1991. The key design parameters and results are reported, including imaging performance down to 0.25 micrometers in both negative and positive resists and a high overlay accuracy based on the TTL alignment system. The capability of matching with i-line systems also is reported.

Wittekoek, Stefan; van den Brink, Martin A.; Poppelaars, G. J.; Reuhman-Huisken, Marijan E.

1993-08-01

224

WIDE-FIELD MULTIBAND PHOTOMETRY OF GLOBULAR CLUSTER SYSTEMS IN THE FORNAX GALAXY CLUSTER  

SciTech Connect

We present wide-field multiband photometry of globular cluster (GC) systems in NGC 1399, NGC 1404, and NGC 1387 located in the central region of the Fornax galaxy cluster. Observation was carried out through U, B, V, and I bands, which marks one of the widest and deepest U-band studies on extragalactic GC systems. The present U-band photometry enables us to significantly reduce the contamination by a factor of two for faint sources (V {sub 0} {approx} 23.5). The main results based on some 2000 GC candidates around NGC 1399, NGC 1404, and NGC 1387 are as follows: (1) the GC system in each galaxy exhibits bimodal color distributions in all colors examined, but the shape of color histograms varies systematically depending on colors; (2) NGC 1399 shows that the mean colors of both blue and red GCs become bluer with increasing galactocentric radius; (3) NGC 1399 shows overabundance of GCs in the directions of NGC 1404 and NGC 1387, indicating their ongoing interactions; and (4) NGC 1399 also exhibits a {approx}0.'5 offset between the center of the inner GC distribution and the galaxy's optical center, suggesting that NGC 1399 is not yet dynamically relaxed and may be undergoing merger events.

Kim, Hak-Sub; Yoon, Suk-Jin; Chung, Chul; Lee, Sang-Yoon; Lee, Young-Wook [Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of)] [Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of); Sohn, Sangmo Tony [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)] [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Kim, Sang Chul [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of)] [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of); Kim, Eunhyeuk, E-mail: sjyoon@galaxy.yonsei.ac.kr [Korea Aerospace Research Institute, Daejeon 305-806 (Korea, Republic of)] [Korea Aerospace Research Institute, Daejeon 305-806 (Korea, Republic of)

2013-01-20

225

Broad- and Narrow-Band Wide-Field Imaging with pODI  

NASA Astrophysics Data System (ADS)

We present preliminary results of two distinct "science verification" observing programs that make use of the pODI instrument on the WIYN 3.5m telescope. This new camera covers a ~0.2 square degree field of view, has a fine pixel scale (0.11"/pixel), and delivers excellent image quality across the entire one-degree field. The first program consisted of observations of an extremely low HI-mass object to search for an optical counterpart (using gri filters) and signs of current star formation (using an H? filter). This object was detected in 21-cm HI emission by the ALFALFA survey and appears as a blue low-surface-brightness galaxy in our deep observations. Second, we have used multiple narrow-band filters to carry out wide field surveys for emission-line sources at various redshifts. We surveyed fields with existing spectroscopic follow-up (COSMOS, DEEP2) and also new fields to detect previously unknown emission-line sources at high redshift. Finally, we demonstrate our use of the ODI Pipeline Portal and Archive system in customizing the reduction and performing some of the data analysis in these projects.

Salzer, John J.; Janowiecki, S.

2013-06-01

226

Wide-field-of-view imaging spectrometer (WFIS): from a laboratory demonstration to a fully functional engineering model  

NASA Astrophysics Data System (ADS)

This paper presents the status of the ongoing development of the laboratory Wide Field-of-view Imaging Spectrometer (WFIS) and the new engineering model WFIS. The design is shown to provide a unique solution to wide field hyperspectral imaging with several advantages over traditional scanning systems. Tests of the engineering model, funded under NASA's Instrument Incubator program, take the WFIS to the next level of technology readiness. The WFIS is based on a patented optical design intended for optical remote sensing of the earth and the earth's atmosphere in the hyperspectral-imaging mode. The design of the laboratory spectrometer and the initial test results obtained with it were presented at the 1999 SPIE Annual Meeting in Denver, Colorado (3759-32). Since that time, the laboratory unit has undergone several upgrades in the optical path and continues to be a pathfinder for the new engineering model instrument. The WFIS engineering model incorporates several improvements to provide increased wavelength coverage from the UV to the NIR and an increase in the field-of-view coverage to 120 degrees. It differs most significantly from the laboratory unit in that it is designed for flight. The status of the hardware, software, and the assembly of the engineering WFIS is discussed as well as an overview of the planned demonstration tests.

Haring, Robert E.; Pollock, Randy; Cross, Richard M.; Greenlee, Terri

2002-02-01

227

Demonstration of the Wide-Field Imaging Interferometer Testbed Using a Calibrated Hyperspectral Image Projector  

NASA Technical Reports Server (NTRS)

The Wide-field Imaging Interferometer testbed (WIIT) at NASA's Goddard Space Flight Center uses a dual-Michelson interferometric technique. The WIIT combines stellar interferometry with Fourier-transform interferometry to produce high-resolution spatial-spectral data over a large field-of-view. This combined technique could be employed on future NASA missions such as the Space Infrared Interferometric Telescope (SPIRIT) and the Sub-millimeter Probe of the Evolution of Cosmic Structure (SPECS). While both SPIRIT and SPECS would operate at far-infrared wavelengths, the WIIT demonstrates the dual-interferometry technique at visible wavelengths. The WIIT will produce hyperspectral image data, so a true hyperspectral object is necessary. A calibrated hyperspectral image projector (CHIP) has been constructed to provide such an object. The CHIP uses Digital Light Processing (DLP) technology to produce customized, spectrally-diverse scenes. CHIP scenes will have approximately 1.6-micron spatial resolution and the capability of . producing arbitrary spectra in the band between 380 nm and 1.6 microns, with approximately 5-nm spectral resolution. Each pixel in the scene can take on a unique spectrum. Spectral calibration is achieved with an onboard fiber-coupled spectrometer. In this paper we describe the operation of the CHIP. Results from the WIIT observations of CHIP scenes will also be presented.

Bolcar, Matthew R.; Leisawitz, David; Maher, Steve; Rinehart, Stephen

2012-01-01

228

FAINT TIDAL FEATURES IN GALAXIES WITHIN THE CANADA-FRANCE-HAWAII TELESCOPE LEGACY SURVEY WIDE FIELDS  

SciTech Connect

We present an analysis of the detectability of faint tidal features in galaxies from the wide-field component of the Canada-France-Hawaii Telescope Legacy Survey. Our sample consists of 1781 luminous (M{sub r{sup '}}<-19.3 mag) galaxies in the magnitude range 15.5 mag < r' < 17 mag and in the redshift range 0.04 < z < 0.2. Although we have classified tidal features according to their morphology (e.g., streams, shells, and tails), we do not attempt to interpret them in terms of their physical origin (e.g., major versus minor merger debris). Instead, we provide a catalog that is intended to provide raw material for future investigations which will probe the nature of low surface brightness substructure around galaxies. We find that around 12% of the galaxies in our sample show clear tidal features at the highest confidence level. This fraction rises to about 18% if we include systems with convincing, albeit weaker tidal features, and to 26% if we include systems with more marginal features that may or may not be tidal in origin. These proportions are a strong function of rest-frame color and of stellar mass. Linear features, shells, and fans are much more likely to occur in massive galaxies with stellar masses >10{sup 10.5} M {sub Sun }, and red galaxies are twice as likely to show tidal features than are blue galaxies.

Atkinson, Adam M.; Abraham, Roberto G. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada)] [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Ferguson, Annette M. N. [Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)] [Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)

2013-03-01

229

Cost-effective and compact wide-field fluorescent imaging on a cell-phone†  

PubMed Central

We demonstrate wide-field fluorescent and darkfield imaging on a cell-phone with compact, light-weight and cost-effective optical components that are mechanically attached to the existing camera unit of the cell-phone. For this purpose, we used battery powered light-emitting diodes (LEDs) to pump the sample of interest from the side using butt-coupling, where the pump light was guided within the sample cuvette to uniformly excite the specimen. The fluorescent emission from the sample was then imaged using an additional lens that was positioned right in front of the existing lens of the cell-phone camera. Because the excitation occurs through guided waves that propagate perpendicular to our detection path, an inexpensive plastic colour filter was sufficient to create the dark-field background required for fluorescent imaging, without the need for a thin-film interference filter. We validate the performance of this platform by imaging various fluorescent micro-objects in 2 colours (i.e., red and green) over a large field-of-view (FOV) of ~81 mm2 with a raw spatial resolution of ~20 ?m. With additional digital processing of the captured cell-phone images, through the use of compressive sampling theory, we demonstrate ~2 fold improvement in our resolving power, achieving ~10 ?m resolution without a trade-off in our FOV. Further, we also demonstrate darkfield imaging of non-fluorescent specimen using the same interface, where this time the scattered light from the objects is detected without the use of any filters. The capability of imaging a wide FOV would be exceedingly important to probe large sample volumes (e.g., >0.1 mL) of e.g., blood, urine, sputum or water, and for this end we also demonstrate fluorescent imaging of labeled white-blood cells from whole blood samples, as well as water-borne pathogenic protozoan parasites such as Giardia Lamblia cysts. Weighing only ~28 g (~1 ounce), this compact and cost-effective fluorescent imaging platform attached to a cell-phone could be quite useful especially for resource-limited settings, and might provide an important tool for wide-field imaging and quantification of various lab-on-a-chip assays developed for global health applications, such as monitoring of HIV+ patients for CD4 counts or viral load measurements.

Zhu, Hongying; Yaglidere, Oguzhan; Su, Ting-Wei; Tseng, Derek

2011-01-01

230

Wide-field direct CCD observations supporting the Astro-1 Space Shuttle mission's Ultraviolet Imaging Telescope  

NASA Technical Reports Server (NTRS)

Wide field direct CCD observations are being obtained to support and complement the vacuum-ultraviolet (VUV) images provided by Astro's Ultraviolet Imaging Telescope (UIT) during a Space Shuttle flight in December 1990. Because of the wide variety of projects addressed by UIT, the fields observed include (1) galactic supernova remnants such as the Cygnus Loop and globular clusters such as Omega Cen and M79; (2) the Magellanic Clouds, M33, M81, and other galaxies in the Local Group; and (3) rich clusters of galaxies, principally the Perseus cluster and Abell 1367. Ground-based observations have been obtained for virtually all of the Astro-1 UIT fields. The optical images allow identification of individual UV sources in each field and provide the long baseline in wavelength necessary for accurate analysis of UV-bright sources. To facilitate use of our optical images for analysis of UIT data and other projects, we plan to archive them, with the UIT images, at the National Space Science Data Center (NSSDC), where they will be universally accessible via anonymous FTP. The UIT, one of three telescopes comprising the Astro spacecraft, is a 38-cm f/9 Ritchey-Chretien telescope on which high quantum efficiency, solar-blind image tubes are used to record VUV images on photographic film. Five filters with passbands centered between 1250A and 2500A provide both VUV colors and a measurement of extinction via the 2200A dust feature. The resulting calibrated VUV pictures are 40 arcminutes in diameter at 2.5 arcseconds resolution. The capabilities of UIT, therefore, complement HST's WFPC: the latter has 40 times greater collecting area, while UIT's usable field has 170 times WFPC's field area.

Hintzen, Paul; Angione, Ron; Talbert, Freddie; Cheng, K.-P.; Smith, Eric; Stecher, Theodore P.

1993-01-01

231

Wide field surveys for submm astronomy with CAMISTIC at Dome C  

NASA Astrophysics Data System (ADS)

The CAMISTIC project aims to install a filled bolometer-array camera with 16x16 pixels on a small telescope (e.g. IRAIT) at Dome C and open the 200-?m (i.e. THz) windows for ground-based observations. CAMISTIC will be located at about 500 m from the base, with very reduced access. Autonomous and automated cryogenic devices specifically designed for the harsh conditions in Antarctica will therefore be needed. We plan to demonstrate the reliability of a novel cryogenic system with all static parts placed next to cryostat at outer temperature conditions and a warmed cabinet for compressors, motors and valves. Extensive tests in wintering condition will be performed before expedition. CAMISTIC will be equipped with novel bolometer technology. The filled bolometer array with a monolithic grid of 256 pixels was designed by CEA for the PACS far-IR/submm imager on the Herschel Space Observatory and similar arrays are currently developed for the ArTéMiS submm camera on ground-based telescopes. A prototype camera operating in the 450 ?m atmospheric window has successfully been tested in March 2006 on the KOSMA telescope. CAMISTIC will perform site testing on the atmospheric opacity and sky noise at 200-450 ?m and then open the way for future, large submm telescopes at Dome C. In the future, placed on a 12-m single-dish telescope at Dome C, a bolometer camera with ~10000 pixels at 200-450 ?m will be particularly powerful to undertake wide field surveys of star-forming complexes in our Galaxy as well as deep field surveys of dust-enshrouded high-redshift galaxies in the early Universe.

Minier, V.; Durand, G. A.; Lagage, P. O.

2006-08-01

232

Towards future systems with nano-optics contributions  

NASA Astrophysics Data System (ADS)

The long anticipated deployment of nano-optics that can enable next generation computing has encountered several practical impediments that have delayed widespread adoption in commercial processes. However, the global market in nano-enabled products is expected to grow to over $80B USD within the next 3 years. In response, the research community is creating solutions to overcome challenging issues such as reliability and cost-effective fabrication. New approaches in sensing, continuous uptime powering, and post silicon manufacturing will maximize overall performance and allow unprecedented commercial applications. This paper reviews present limitations of nano-optics and then considers the new generation of devices and their manufacturing that may turn promises into reality. We highlight several recent innovations: high sensitivity/selectivity nano-optical sensing devices; sustainable power from polymer energy harvesting and storage; optical variable devices for visual authentication of secure documents; and nano-template masters for high-volume manufacturing.

Kaminska, Bozena; Najiminaini, Mohamadreza; Chuo, Yindar; Landrock, Clint; Omrane, Badr; Carson, Jeffrey J. L.

2013-03-01

233

Adaptive optics schemes for future extremely large telescopes  

NASA Astrophysics Data System (ADS)

The adaptive optics for any telescope in the 25- to 100-m class will be complex. It is believed that adaptive optics should, to the maximum extent, be designed as an integrated part of a telescope. The proposed Swedish 50-m Extremely Large Telescope is considered here to illustrate the principle of integrated adaptive optics. Two alternative designs both using the Ritchey-Chretien telescope system and laser guide star (LGS) reference sources are presented. The first design employs trombone optics, which bring the laser guide star images back to the normal Ritchey-Chretien focal surface (referred to as the RC-focus) from the LGS focal surface (referred to as the LRC-focus), and a layer-oriented wavefront sensor system optically performing the averaging `shift and add' in the final focus. According to this procedure, sensed wavefronts are overlapped with a certain mutual shift and added for estimation of wavefront average slope values, resulting in actuator commands for driving the shape of the deformable mirrors. The second design employs a numerical `shift and add' procedure and has two wavefront sensors. The first one performs LGS sensing in an intermediate focus (LRC-focus), giving the input data for an analytical algorithm for deriving the mirror deformations to correct for atmospheric turbulence. By using an artificial laser source at the intermediate focus, the shape of the second deformable mirror is controlled by a second wavefront sensor in the final focus. The capability of the analytical algorithm to derive the mirror corrections from the measured wavefronts ensures proper functioning of the adaptive optics system. This system has a simpler optical design compared to the first design.

Goncharov, Alexander V.; Owner-Petersen, Mette; Andersen, Torben; Beckers, Jacques M.

2002-05-01

234

The development of high-precision hexapod actuators for the Hobby-Eberly Telescope wide field upgrade  

NASA Astrophysics Data System (ADS)

Hexapods are finding increased use in telescope applications for positioning large payloads. Engineers from The University of Texas at Austin have been working with engineers from ADS International to develop large, high force, highly precise and controllable hexapod actuators for use on the Wide Field Upgrade (WFU) as part of the Hobby Eberly Telescope Dark Energy Experiment (HETDEX)?. These actuators are installed in a hexapod arrangement, supporting the 3000+ kg instrument payload which includes the Wide Field Corrector (WFC), support structure, and other optical/electronic components. In addition to force capability, the actuators need to meet the tracking speed (pointing) requirements for accuracy and the slewing speed (rewind) requirements, allowing as many observations in one night as possible. The hexapod actuator stroke (retraction and extension) was very closely monitored during the design phase to make sure all of the science requirements could be met, while minimizing the risk of damaging the WFC optical hardware in the unlikely event of a hexapod actuator or controller failure. This paper discusses the design trade-offs between stiffness, safety, back-drivability, accuracy, and leading to selection of the motor, high ratio worm gear, roller screw, coupling, end mounts, and other key components.

Zierer, Joseph J.; Mock, Jason R.; Beno, Joseph H.; Good, John; Booth, John A.; Lazzarini, Paolo; Fumi, Pierluigi; Anaclerio, Enzo

2010-07-01

235

Photonic crystals in the optical regime — past, present and future  

Microsoft Academic Search

During the last decade, photonic crystals, also known as photonic microstructures or photonic bandgap structures, have matured from an intellectual curiosity concerning electromagnetic waves to a field with real applications in both the microwave and optical regime. In this review, we shall focus on progress and the prospects for semiconductor structures that mainly involve guided modes interacting with periodic structures,

Thomas F. Krauss; Richard M. De La Rue

1999-01-01

236

Neutron polycapillary optics: present status and future trends  

NASA Astrophysics Data System (ADS)

Up to present, neutron applications of polycapillary optics have been rather rear and mostly limited either to feasibility studies or to non-scattering techniques. The practical use of polycapillary focusing neutron optics for purposes of neutron scattering have been hindered by a serious degradation of momentum resolution caused by increased divergence of focused beams. However, limited size of samples available for research as well as limited brightness of present day neutron sources (both reactors and spallation sources) requires to rethink the current situation. Neutron lenses are successfully tested for low Q-resolution applications providing an enormous increase of neutron flux at small samples. Moreover, some recent developments in the field of neutron instrumentation allow us to overcome the resolution problem by decoupling the angular resolution and the incident beam divergence thus opening the opportunity for the use of focusing neutron optics in some high Q-resolution application. Further advances in technology required to improve the performance of neutron polycapillary optics, also in combination with modem methods of polarization of neutron beams, are discussed.

Ioffe, A.

2005-07-01

237

Retinal optical coherence tomography: past, present and future perspectives  

Microsoft Academic Search

Optical coherence tomography (OCT) has undergone substantial changes since its first use in the 1990s. Although the first generation of OCT systems heralded a new era in the non-invasive diagnostic options in ophthalmology, they did not reveal much detail. Later devices offered more information and helped in the diagnosis and treatment of a variety of pathological conditions, primarily of the

Wolfgang Geitzenauer; Christoph K Hitzenberger; Ursula M Schmidt-Erfurth

2010-01-01

238

A Panchromatic Catalog of Early-type Galaxies at Intermediate Redshift in the Hubble Space Telescope Wide Field Camera 3 Early Release Science Field  

NASA Astrophysics Data System (ADS)

In the first of a series of forthcoming publications, we present a panchromatic catalog of 102 visually selected early-type galaxies (ETGs) from observations in the Early Release Science (ERS) program with the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope (HST) of the Great Observatories Origins Deep Survey-South (GOODS-S) field. Our ETGs span a large redshift range, 0.35 lsim z lsim 1.5, with each redshift spectroscopically confirmed by previous published surveys of the ERS field. We combine our measured WFC3 ERS and Advanced Camera for Surveys (ACS) GOODS-S photometry to gain continuous sensitivity from the rest-frame far-UV to near-IR emission for each ETG. The superior spatial resolution of the HST over this panchromatic baseline allows us to classify the ETGs by their small-scale internal structures, as well as their local environment. By fitting stellar population spectral templates to the broadband photometry of the ETGs, we determine that the average masses of the ETGs are comparable to the characteristic stellar mass of massive galaxies, 1011 < M *[M ?]<1012. By transforming the observed photometry into the Galaxy Evolution Explorer FUV and NUV, Johnson V, and Sloan Digital Sky Survey g' and r' bandpasses we identify a noteworthy diversity in the rest-frame UV-optical colors and find the mean rest-frame (FUV-V) = 3.5 and (NUV-V) = 3.3, with 1? standard deviations sime1.0. The blue rest-frame UV-optical colors observed for most of the ETGs are evidence for star formation during the preceding gigayear, but no systems exhibit UV-optical photometry consistent with major recent (lsim50 Myr) starbursts. Future publications which address the diversity of stellar populations likely to be present in these ETGs, and the potential mechanisms by which recent star formation episodes are activated, are discussed.

Rutkowski, M. J.; Cohen, S. H.; Kaviraj, S.; O'Connell, R. W.; Hathi, N. P.; Windhorst, R. A.; Ryan, R. E., Jr.; Crockett, R. M.; Yan, H.; Kimble, R. A.; Silk, J.; McCarthy, P. J.; Koekemoer, A.; Balick, B.; Bond, H. E.; Calzetti, D.; Disney, M. J.; Dopita, M. A.; Frogel, J. A.; Hall, D. N. B.; Holtzman, J. A.; Paresce, F.; Saha, A.; Trauger, J. T.; Walker, A. R.; Whitmore, B. C.; Young, E. T.

2012-03-01

239

The Wide-field High-resolution Infrared TElescope (WHITE) for Dome C  

NASA Astrophysics Data System (ADS)

The Wide-field High-resolution Infrared TElescope (WHITE) that we propose for Dome C will be dedicated in the first years of its life to carry out a few legacy surveys (well-focused in terms of science objectives and time). WHITE would have an angular resolution of ~0.3'' uniform over ~0.7 sq. deg. in the wavelength range 1~?m to 5~?m, which means that we will very efficiently use all the available observational time during night time and day time. Moreover, the deepest observations will be performed by summing up shorter individual frames. We will obtain temporal information that can be used to study variable objects. The three key science objectives of WHITE are: 1) A survey of the Magellanic Clouds to make a complete census of young stellar objects in the Clouds and in the Bridge and to study their star formation history and the link with the Milky Way. The interaction of the two Clouds with our Galaxy might be the closest example of a minor merging event that could be the main driver of galaxy evolution in the last 5 Gyrs. 2) Establishing of the first sample of dusty supernovae at z < 1.2 in the near infrared range (1.0 - 5.0~?m) to constrain the equation of state of these obscured objects, study the formation of dust in galaxies, and build the first high resolution sample of high-redshift galaxies observed in their optical frame 3) A very wide weak lensing survey that would allow to estimate the equation of state of dark energy in a way that would favourably compete with space projects.

Burgarella, D.; Le Roux, B.; Langlois, M.; Moretto, G.; Fusco, T.; Ferrari, M.

240

Discovery of two new Galactic candidate luminous blue variables with Wide-field Infrared Survey Explorer  

NASA Astrophysics Data System (ADS)

We report the discovery of two new Galactic candidate luminous blue variable (LBV) stars via detection of circular shells (typical of confirmed and candidate LBVs) and follow-up spectroscopy of their central stars. The shells were detected at 22 ?m in the archival data of the Mid-Infrared All Sky Survey carried out with the Wide-field Infrared Survey Explorer (WISE). Follow-up optical spectroscopy of the central stars of the shells conducted with the renewed Southern African Large Telescope (SALT) showed that their spectra are very similar to those of the well-known LBVs P Cygni and AG Car, and the recently discovered candidate LBV MN112, which implies the LBV classification for these stars as well. The LBV classification of both stars is supported by detection of their significant photometric variability: one of them brightened in the R and I bands by 0.68 ± 0.10 and 0.61 ± 0.04 mag, respectively, during the last 13-18 years, while the second one (known as Hen 3-1383) varies its B, V, R, I and Ks brightnesses by ?0.5-0.9 mag on time-scales from 10 d to decades. We also found significant changes in the spectrum of Hen 3-1383 on a time-scale of ?3 months, which provides additional support for the LBV classification of this star. Further spectrophotometric monitoring of both stars is required to firmly prove their LBV status. We discuss a connection between the location of massive stars in the field and their fast rotation, and suggest that the LBV activity of the newly discovered candidate LBVs might be directly related to their possible runaway status. a USNO B-1 (Monet et al. 2003); bDENIS; c2MASS; dSALT; ePROMPT.

Gvaramadze, V. V.; Kniazev, A. Y.; Miroshnichenko, A. S.; Berdnikov, L. N.; Langer, N.; Stringfellow, G. S.; Todt, H.; Hamann, W.-R.; Grebel, E. K.; Buckley, D.; Crause, L.; Crawford, S.; Gulbis, A.; Hettlage, C.; Hooper, E.; Husser, T.-O.; Kotze, P.; Loaring, N.; Nordsieck, K. H.; O'Donoghue, D.; Pickering, T.; Potter, S.; Romero Colmenero, E.; Vaisanen, P.; Williams, T.; Wolf, M.; Reichart, D. E.; Ivarsen, K. M.; Haislip, J. B.; Nysewander, M. C.; LaCluyze, A. P.

2012-04-01

241

Cone of Darkness: Finding Blank-sky Positions for Multi-object Wide-field Observations  

NASA Astrophysics Data System (ADS)

We present the Cone of Darkness, an application to automatically configure blank-sky positions for a series of stacked, wide-field observations, such as those carried out by the SAMI instrument on the Anglo-Australian Telescope (AAT). The Sydney-AAO Multi-object Integral field spectrograph (SAMI) uses a plug-plate to mount its 13×61 core imaging fibre bundles (hexabundles) in the optical plane at the telescope's prime focus. To make the most efficient use of each plug-plate, several observing fields are typically stacked to produce a single plate. When choosing blank-sky positions for the observations it is most effective to select these such that one set of 26 holes gives valid sky positions for all fields on the plate. However, when carried out manually this selection process is tedious and includes a significant risk of error. The Cone of Darkness software aims to provide uniform blank-sky position coverage over the field of observation, within the limits set by the distribution of target positions and the chosen input catalogs. This will then facilitate the production of the best representative median sky spectrum for use in sky subtraction. The application, written in C++, is configurable, making it usable for a range of instruments. Given the plate characteristics and the positions of target holes, the software segments the unallocated space on the plate and determines the position which best fits the uniform distribution requirement. This position is checked, for each field, against the selected catalog using a TAP ADQL search. The process is then repeated until the desired number of sky positions is attained.

Lorente, N. P. F.

2014-05-01

242

Wide-field Precision Kinematics of the M87 Globular Cluster System  

NASA Astrophysics Data System (ADS)

We present the most extensive combined photometric and spectroscopic study to date of the enormous globular cluster (GC) system around M87, the central giant elliptical galaxy in the nearby Virgo Cluster. Using observations from DEIMOS and the Low Resolution Imaging Spectrometer at Keck, and Hectospec on the Multiple Mirror Telescope, we derive new, precise radial velocities for 451 GCs around M87, with projected radii from ~5 to 185 kpc. We combine these measurements with literature data for a total sample of 737 objects, which we use for a re-examination of the kinematics of the GC system of M87. The velocities are analyzed in the context of archival wide-field photometry and a novel Hubble Space Telescope catalog of half-light radii, which includes sizes for 344 spectroscopically confirmed clusters. We use this unique catalog to identify 18 new candidate ultracompact dwarfs and to help clarify the relationship between these objects and true GCs. We find much lower values for the outer velocity dispersion and rotation of the GC system than in earlier papers and also differ from previous work in seeing no evidence for a transition in the inner halo to a potential dominated by the Virgo Cluster, nor for a truncation of the stellar halo. We find little kinematical evidence for an intergalactic GC population. Aided by the precision of the new velocity measurements, we see significant evidence for kinematical substructure over a wide range of radii, indicating that M87 is in active assembly. A simple, scale-free analysis finds less dark matter within ~85 kpc than in other recent work, reducing the tension between X-ray and optical results. In general, out to a projected radius of ~150 kpc, our data are consistent with the notion that M87 is not dynamically coupled to the Virgo Cluster; the core of Virgo may be in the earliest stages of assembly.

Strader, Jay; Romanowsky, Aaron J.; Brodie, Jean P.; Spitler, Lee R.; Beasley, Michael A.; Arnold, Jacob A.; Tamura, Naoyuki; Sharples, Ray M.; Arimoto, Nobuo

2011-12-01

243

GALEX Wide-field Ultraviolet Imaging of NGC 5128 (Centaurus-A)  

NASA Technical Reports Server (NTRS)

We present new wide-field ultraviolet (UV) observations of the nearby active galaxy NGC 5128 (Centaurus A). The GALEX images provide 3.5 sec - 5.5 sec resolution over a 1.2 degree field, in two broad bands (1350- 1800A and 1800-3000A, centered at 1550A and 2200A). We detect ultraviolet emission associated with the radio and X-ray jets in both bands, extending out to a distance of approx. 40kpc from the galaxy nucleus. We compare the radio, X-ray, and UV jets, and discuss the feasibility of jet-induced star formation. We show how the UV emission relates to the optical filaments: HI and CO clouds, stellar shells, X-ray arcs, and young star chains previously reported by other authors. In the central region of NGC 5128, we detect UV emission from young super-star-clusters and associated ionized gas located along the near edge and on the upper surface of the dusty warped disk. All of the UV emission in the galaxy appears to result from intense star formation in the disk; none appears to be associated with the old stellar population of the main galaxy body, and no UV emission from the AGN is detected. We estimate the numbers and ages of the massive young stars present, and the associated ionized gas masses. Finally, we compare Cen-A to high redshift radio galaxies which were much more numerous in the earlier universe. The GALEX satellite is a NASA Small Explorer, launched in April 2003. We gratefully acknowledge NASA's support for construction, operation, and science analysis for the GALEX mission.

Neff, S. G.; Shiminovich, D.; Martin, C. D.

2004-01-01

244

A Light and Effective Wide Field Monitor for Gamma Ray Bursts and Transient Sources  

SciTech Connect

We present here a concept for a light and low-power wide field monitor working in the X-ray range, suitable for simultaneous imaging of large portions of the sky and GRB localizations. Our concept evolves from and improves on the design of the 5-kg SuperAGILE experiment, flying on the AGILE mission and currently delivering arcmin-localizations of GRBs at a rate of about 1/month. Similar to SuperAGILE, our concept is based on position sensitive silicon detectors equipped with one-dimensional coded masks. Different options are available for the detector, whose properties, combined with the scientific requirements, drive the design of the experiment. Our approach is based on a modular detector. The experiment design can then be tailored to specific scientific goals of the experiment or the mission (e.g., to cite GRBs only: the brightest GRBs/XRFs on a large field of view - FoV, or many low-fluence GRBs/XRFs on a smaller FoV, or the low energy spectrum of the prompt event, or the detection of high-z GRBs). In this paper we describe the concept, the main detector properties and outline some possible experiment configurations, with examples of their expected performance. Different experiment configurations in terms of area, FoV, angular resolution may be designed starting from the same detectors. Instead, the band-pass is mostly related to the detector properties. A key point of our project is the high degree of readiness of the detectors that are at production level and may be immediately proposed for a future experiment onboard missions with high readiness requirements.

Feroci, M.; Campana, R.; Costa, E.; Del Monte, E.; Donnarumma, I.; Evangelista, Y.; Lazzarotto, F.; Mastropietro, M.; Muleri, F.; Pacciani, L.; Rubini, A.; Soffitta, P. [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica-Roma (Italy); Amati, L.; Fuschino, F.; Labanti, C.; Marisaldi, M.; Morelli, E.; Orlandini, M. [INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica-Bologna (Italy); Antonelli, L. A.; Fiore, F. [INAF-Osservatorio Astronomico di Roma-Monteporzio Catone (Italy)] (and others)

2009-05-25

245

Optical coherence elastography: current status and future applications  

NASA Astrophysics Data System (ADS)

Optical coherence tomography (OCT) has several advantages over other imaging modalities, such as angiography and ultrasound, due to its inherently high in vivo resolution, which allows for the identification of morphological tissue structures. Optical coherence elastography (OCE) benefits from the superior spatial resolution of OCT and has promising applications, including cancer diagnosis and the detailed characterization of arterial wall biomechanics, both of which are based on the elastic properties of the tissue under investigation. We present OCE principles based on techniques associated with static and dynamic tissue excitation, and their corresponding elastogram image-reconstruction algorithms are reviewed. OCE techniques, including the development of intravascular- or catheter-based OCE, are in their early stages of development but show great promise for surgical oncology or intravascular cardiology applications.

Sun, Cuiru; Standish, Beau; Yang, Victor X. D.

2011-04-01

246

Mosaiced wide-field VLBI observations of the Lockman Hole/XMM  

NASA Astrophysics Data System (ADS)

Active galactic nuclei (AGN) play a decisive role in galaxy evolution, particularly so when they launch powerful jets, which reshape their surroundings. However, identifying them is difficult, since radio observations typically have a resolution between 1 arcsec and 10 arcsec, which is equally sensitive to radio emission from star-forming activity and from AGN. Very Long Baseline Interferometry (VLBI) observations allow only the most compact non-thermal emission to be filtered from radio survey data. The observational and computational demands to do this in large surveys have, until recently, been too high to make this practical. Only the recent advent of wide-field observing techniques have enabled such observations, and we here present the results of a survey of 217 radio sources in the Lockman Hole/XMM field. We describe in detail some new aspects of the calibration, including primary beam correction, multi-source self-calibration, and mosaicing. We detected 65 out of the 217 radio sources and were able to construct, for the first time, the source counts of VLBI-detected AGN. The source counts indicate that at least 15-25% of the sub-mJy radio sources are AGN-driven, consistent with recent findings using other AGN selection techniques. We have used optical, infrared and X-ray data to enhance our data set and to investigate the AGN hosts. We find that among the sources nearby enough to be resolved in the optical images, 88% (23/26) could be classified as early-type or bulge-dominated galaxies. While 50% of these sources are correctly represented by the SED of an early-type galaxy, the best fit for the remainder was obtained with a heavily extinct starburst template. However, this is due to a degeneracy in the fit, as such extinction in the templates is mimicking early-type objects. Our data suggest that the hosts of VLBI-detected sources are typically early-type or bulge-dominated galaxies. Tables 6, 7, and Figs. 21-24 are available in electronic form at http://www.aanda.org

Middelberg, E.; Deller, A. T.; Norris, R. P.; Fotopoulou, S.; Salvato, M.; Morgan, J. S.; Brisken, W.; Lutz, D.; Rovilos, E.

2013-03-01

247

Optical Tweezers and Optical Trapping Improved for Future Automated Micromanipulation and Characterization.  

National Technical Information Service (NTIS)

Optical trap arrays are being developed at the NASA Glenn Research Center for holding, manipulating, and optically interrogating arrays of nanotube sensors. The trap arrays, for example, might be used to arrange arrays of chemical sensors for insertion on...

S. Y. Wrbanek A. J. Decker

2005-01-01

248

The study of large-scale structures with wide-field X-ray optics  

NASA Astrophysics Data System (ADS)

A Scout-class explorer mission capable of studying evolution and structures on the largest scales in the universe is described. It is argued that the presently planned instruments have limitations that are not related to collecting area but are caused by a limited field of view. From galaxy cluster studies by Burg et al. (1989) and Cavaliere, Burg, and Giacconi (1989), it is concluded that the luminosity function at the current epoch is not sufficient to disentangle the various contributions of cosmology (the density fluctuation spectrum) and astrophysics (structural evolution and gas injection). An optimizing ray tracing code is derived where the solid angle weight point response function was minimized over the desired field of view. The design of a telescope which has an angular resolution of better than 2.5 arcsec rms when averaged over a 30-arcmin-radius field of view is presented.

Burg, Richard; Burrows, Christopher J.; Giacconi, Riccardo

1990-08-01

249

Panchromatic properties of galaxies in wide-field optical spectroscopic and photometric surveys  

NASA Astrophysics Data System (ADS)

The past 15 years have seen an explosion in the number of redshifts recovered via wide area spectroscopic surveys. At the current time there are approximately 2 million spectroscopic galaxy redshifts known (and rising) which represents an extraordinary growth since the pioneering work of Marc Davis and John Huchra. Similarly there has been a parallel explosion in wavelength coverage with imaging surveys progressing from single band, to multi-band, to truly multiwavelength or pan-chromatic involving the coordination of multiple facilities. With these empirically motivated studies has come a wealth of new discoveries impacting almost all areas of astrophysics. Today individual surveys, as best demonstrated by the Sloan Digital Sky Survey, now rank shoulder-to-shoulder alongside major facilities. In the coming years this trend is set to continue as we begin the process of designing and conducting the next generation of spectroscopic surveys supported by multi-facility wavelength coverage.

Driver, Simon P.

2012-08-01

250

An impairment-aware virtual optical network composition mechanism for future Internet.  

PubMed

In this paper, a novel Infrastructure as a Service architecture for future Internet enabled by optical network virtualization is proposed. Central to this architecture is a novel virtual optical network (VON) composition mechanism capable of taking physical layer impairments (PLIs) into account. The impact of PLIs on VON composition is investigated based on both analytical model of PLIs and industrial parameters. Furthermore, the impact of network topology on VON composition is evaluated. PMID:22274026

Peng, Shuping; Nejabati, Reza; Azodolmolky, Siamak; Escalona, Eduard; Simeonidou, Dimitra

2011-12-12

251

Flight performance of an advanced CZT imaging detector in a balloon-borne wide-field hard X-ray telescope—ProtoEXIST1  

NASA Astrophysics Data System (ADS)

We successfully carried out the first high-altitude balloon flight of a wide-field hard X-ray coded-aperture telescope ProtoEXIST1, which was launched from the Columbia Scientific Balloon Facility at Ft. Sumner, New Mexico on October 9, 2009. ProtoEXIST1 is the first implementation of an advanced CdZnTe (CZT) imaging detector in our ongoing program to establish the technology required for next generation wide-field hard X-ray telescopes such as the High Energy Telescope (HET) in the Energetic X-ray Imaging Survey Telescope (EXIST). The CZT detector plane in ProtoEXIST1 consists of an 8×8 array of closely tiled 2 cm×2 cm×0.5 cm thick pixellated CZT crystals, each with 8×8 pixels, mounted on a set of readout electronics boards and covering a 256 cm2 active area with 2.5 mm pixels. A tungsten mask, mounted at 90 cm above the detector provides shadowgrams of X-ray sources in the 30-600 keV band for imaging, allowing a fully coded field of view of 9°×9° (and 19°×19° for 50% coding fraction) with an angular resolution of 20?. In order to reduce the background radiation, the detector is surrounded by semi-graded (Pb/Sn/Cu) passive shields on the four sides all the way to the mask. On the back side, a 26 cm×26 cm×2 cm CsI(Na) active shield provides signals to tag charged particle induced events as well as ?100keV background photons from below. The flight duration was only about 7.5 h due to strong winds (60 knots) at float altitude (38-39 km). Throughout the flight, the CZT detector performed excellently. The telescope observed Cyg X-1, a bright black hole binary system, for ˜1h at the end of the flight. Despite a few problems with the pointing and aspect systems that caused the telescope to track about 6.4° off the target, the analysis of the Cyg X-1 data revealed an X-ray source at 7.2? in the 30-100 keV energy band at the expected location from the optical images taken by the onboard daytime star camera. The success of this first flight is very encouraging for the future development of the advanced CZT imaging detectors (ProtoEXIST2, with 0.6 mm pixels), which will take advantage of the modularization architecture employed in ProtoEXIST1.

Hong, J.; Allen, B.; Grindlay, J.; Barthelemy, S.; Baker, R.; Garson, A.; Krawczynski, H.; Apple, J.; Cleveland, W. H.

2011-10-01

252

Micrometeoroid Impacts on the Hubble Sace Telescope Wide Field and Planetary Camera 2: Ion Beam Analysis of Subtle Impactor Traces  

NASA Technical Reports Server (NTRS)

Recognition of origin for particles responsible for impact damage on spacecraft such as the Hubble Space Telescope (HST) relies upon postflight analysis of returned materials. A unique opportunity arose in 2009 with collection of the Wide Field and Planetary Camera 2 (WFPC2) from HST by shuttle mission STS-125. A preliminary optical survey confirmed that there were hundreds of impact features on the radiator surface. Following extensive discussion between NASA, ESA, NHM and IBC, a collaborative research program was initiated, employing scanning electron microscopy (SEM) and ion beam analysis (IBA) to determine the nature of the impacting grains. Even though some WFPC2 impact features are large, and easily seen without the use of a microscope, impactor remnants may be hard to find.

Grime, G. W.; Webb, R. P.; Jeynes, C.; Palitsin, V. V.; Colaux, J. L.; Kearsley, A. T.; Ross, D. K.; Anz-Meador, P.; Liou, J. C.; Opiela, J.; Griffin, T.; Gerlach, L.; Wozniakiewicz, P. J.; Price, M. C.; Burchell, M. J.; Cole, M. J.

2014-01-01

253

PyWiFeS: a rapid data reduction pipeline for the Wide Field Spectrograph (WiFeS)  

NASA Astrophysics Data System (ADS)

We present PyWiFeS, a new Python-based data reduction pipeline for the Wide Field Spectrograph (WiFeS). PyWiFeS consists of a series of core data processing routines built on standard scientific Python packages commonly used in astronomical applications. Included in PyWiFeS is an implementation of a new global optical model of the spectrograph which provides wavelengths solutions accurate to ˜0.05 Å (RMS) across the entire detector. The core PyWiFeS package is designed to be scriptable to enable batch processing of large quantities of data, and we present a default format for handling of observation metadata and scripting of data reduction.

Childress, Michael J.; Vogt, Frédéric P. A.; Nielsen, Jon; Sharp, Robert G.

2014-02-01

254

A method for the use of ellipticities and spot diameters for the measurement of aberrations in wide-field telescopes  

NASA Astrophysics Data System (ADS)

In wide-field survey telescopes, the patterns of spot sizes and ellipticities can be used to determine wavefront aberrations generated by the telescope. The calculation of spot sizes and ellipticities generated by telescope aberrations is most conveniently done if the aberrations are expressed in terms of Zernike-type polynomials whose derivatives are orthonormal. The field dependence of the spot sizes and ellipticities generated by the telescope can conveniently be expressed by low-order Zernike polynomials. Because the exposure times in astronomical survey work are typically rather short, this information may be used for a quasi-closed loop control of the telescope optics. The ability to accurately subtract ellipticities generated by telescope errors could also be useful for observations such as gravitational lensing surveys.

Noethe, Lothar; Schipani, Pietro; Holzlöhner, Ronald; Rakich, Andrew

2014-06-01

255

Sampling and Analysis of Impact Crater Residues found on the Wide Field Planetary Camera-2 Radiator  

NASA Technical Reports Server (NTRS)

After nearly 16 years on orbit, the Wide Field Planetary Camera-2 (WFPC-2) was recovered from the Hubble Space Telescope in May 2009 during the 12 day shuttle mission designated STS-125. During that exposure to the low Earth orbit environment, the WFPC-2 radiator was struck by approximately 700 impactors producing crater features 300 micrometers and larger in size. Following an optical inspection of these features in 2009, an agreement was reached for the joint NASA-ESA examination and characterization of crater residues, the remnants of the projectile, in 2011. Active examination began in 2012, with 486 of the impact features being cored at NASA Johnson Space Center fs (JSC) Space Exposed Hardware cleanroom and curation facility. The core samples were subsequently divided between NASA and ESA. NASA's analysis was conducted at JSC fs Astromaterials Research and Exploration Science (ARES) Division, using scanning electron microscopy (SEM)/ energy dispersive X-ray spectrometry (EDS) methods, and ESA's analysis was conducted at the Natural History Museum (NHM) again using SEM/EDS, and at the University of Surrey Ion Beam Centre (IBC) using ion beam analysis (IBA) with a scanned proton microbeam. As detailed discussion of the joint findings remains premature at this point, this paper reports on the coring technique developed; the practical taxonomy developed to classify residues as belonging either to anthropogenic "orbital debris" or micrometeoroids; and the protocols for examination of crater residues. Challenges addressed in coring were the relative thickness of the surface to be cut, protection of the impact feature from contamination while coring, and the need to preserve the cleanroom environment so as to preclude or minimize cross-contamination. Classification criteria are summarized, including the assessment of surface contamination and surface cleaning. Finally, we discuss the analytical techniques used to examine the crater residues. We employed EDS from either electron excitation (SEM-EDS) and, in a minority of cases for cores assessed as "difficult" targets, proton excitation (IBA). All samples were documented by electron imagery: backscattered electron imagery in the SEM, and where appropriate, secondary electron imagery during IBA.

Kearsley, A. T.; Grime, G. W.; Colaux, J. L.; Jeynes, C.; Palitsin, V. V.; Webb, R. P.; Griffin, T. J.; Reed, B. B.; Anz-Meador, P. D.; Kou, J.-C.; Robinson, G. A.; Opiela, J. N.; Gerlach, L.

2013-01-01

256

Wide Field Planetary Camera 2 Observations of the Polar Ring Galaxy NGC 4650A  

NASA Astrophysics Data System (ADS)

We present multicolor Wide Field Planetary Camera 2 images of the polar ring galaxy NGC 4650A (D=35 Mpc), taken with the Hubble Space Telescope. These data allow a detailed examination of the morphology of the central S0 component and the surrounding ``polar ring'' of stars, gas, and dust, which are spatially extended and form a ``polar disk.'' The nuclear complex, located near the common center of the two components, consists of an unresolved compact source less than 20 pc across, embedded in a more extended light distribution about 60 pc in radius. A complicated pattern of dust lanes crosses the high surface brightness central region of the S0, where dust features appear to extend inward to small radii. In areas of the S0 exterior to the projected polar disk, the light distribution is relatively smooth on small spatial scales, with few candidates for old star clusters or signs of internal dust features. Outer regions of the S0 galaxy have uniformly red colors of a stellar population where major star formation ceased ~3-5 Gyr in the past. The polar disk appears to be warped, with a complex morphology. On small spatial scales, features are produced mainly by dust and clumps of star formation; gas seems to be piling up in a dusty ring that encircles the central S0 at a radius of ~1 kpc (6"). The polar disk is inclined by about 63° near its center, twists toward edge-on at intermediate radii, and again becomes more nearly face-on further out, where two spiral arms are marked by young stars. We do not detect any regions with a prominent ``Baade sheet'' of older red stars in the polar disk; most of the optical light is supplied by moderately young stars, with lifetimes of ~1 Gyr. The polar material appears relatively unevolved, especially when compared to the S0 component of NGC 4650A. Either the polar disk is a late addition to the system or the outer gas has formed very few stars until recently. Observations obtained with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS5-26555.

Gallagher, J. S.; Sparke, L. S.; Matthews, L. D.; Frattare, L. M.; English, J.; Kinney, A. L.; Iodice, E.; Arnaboldi, M.

2002-03-01

257

Novae in M31 discovered with wide field telescopes in Crimea and Latvia  

Microsoft Academic Search

Data on 21 novae in M31 discovered from 1969 to 1989 with wide field telescopes at the Crimean Station of the Sternberg Astronomical Institute and at the Radioastrophysical Observatory in Baldone near Riga, Latvia, are presented. Novae in the disk of M31 are encountered up to 20 kpc and larger distances from its center. Light curves of the discovered novae

A. S. Sharov; A. Alksnis

1991-01-01

258

Application of the wide-field shadowgraph technique to rotor wake visualization  

NASA Technical Reports Server (NTRS)

The wide field shadowgraph technique is reviewed along with its application to the visualization of rotor wakes. In particular, current experimental methods and data reduction requirements are discussed. Sample shadowgraphs are presented. These include shadowgraphs of model-scale helicopter main rotors and tilt rotors, and full scale tail rotors, both in hover and in forward flight.

Norman, Thomas R.; Light, Jeffrey S.

1989-01-01

259

Astronaut Jeffrey Hoffman with Wide Field/Planetary Camera during EVA  

NASA Technical Reports Server (NTRS)

Astronaut Jeffrey A. Hoffman with Wide Field/Planetary Camera (WF/PC 1) in payload bay during changeout operations. Hoffman is standing on a foot restraint attached to the robot arm of the Remote Manipulator System (RMS) in order to remove the old WF/PC. The new WF/PC has already been installed in cavity (out of frame).

1993-01-01

260

Saturn's hydrogen aurora: Wide field and planetary camera 2 imaging from the Hubble Space Telescope  

Microsoft Academic Search

Wide field and planetary camera 2\\/Hubble Space Telescope (WFPC2\\/HST) images of Saturn's far ultraviolet aurora reveal emissions confined to a narrow band of latitudes near Saturn's north and south poles. The aurorae are most prominent in the morning sector with patterns that appear fixed in local time. The geographic distribution and vertical extent of the auroral emissions seen in these

John T. Trauger; John T. Clarke; Gilda E. Ballester; Robin W. Evans; Christopher J. Burrows; David Crisp; John S. Gallagher; Richard E. Griffiths; J. Jeff Hester; John G. Hoessel; Jon A. Holtzman; John E. Krist; Jeremy R. Mould; Raghvendra Sahai; Paul A. Scowen; Karl R. Stapelfeldt; Alan M. Watson

1998-01-01

261

The wide-field imaging interferometry testbed: II. Characterization and calibration  

Microsoft Academic Search

We discuss the procedure used to characterize the Wide-Field Imaging Interferometry Testbed (WIIT) components and system, including spectral transmission, throughput, wavefront quality, mechanical and thermal stability, and susceptibility to turbulence. The sources of uncertainty and visibility loss are identified and evaluated, and we briefly discuss measures taken to mitigate these effects. We further discuss calibration techniques which can be used

Stephen A. Rinehart; J. T. Armstrong; Bradley J. Frey; Jeff Kirk; David T. Leisawitz; Douglas B. Leviton; Luke W. Lobsinger; Richard G. Lyon; Anthony J. Martino; Thomas A. Pauls; Lee G. Mundy; E. Sears

2004-01-01

262

Estimated performance of the Wide-field Infrared Explorer (WIRE) instrument  

Microsoft Academic Search

The Wide-Field IR Explorer (WIRE) is a small spaceborne cryogenic IR telescope being readied for launch in September 1998. Part of NASA's Small Explorer program, WIRE will carry out a deep pointed survey in broad 24 and 12 micron passbands designed primarily to study the evolution of starburst galaxies and to search for protogalaxies. The strategy for the WIRE survey

David L. Shupe; Mark F. Larsen; Steven D. Sargent; James Q. Peterson; Joseph J. Tansock; Thomas S. Luchik; Perry B. Hacking; Terry L. Herter

1998-01-01

263

Wide-field interferometric phase imaging of plasmonic nanoparticles at the subcellular level  

NASA Astrophysics Data System (ADS)

We present a new wide-field quantitative photothermal (PT) imaging method of gold nanoparticles (AuNPs), which is suitable for obtaining wide-field holographic molecular specificity in biological samples. To obtain this goal, we built a wide-field interferometric phase microscope and modified it for the excitation of plasmonic resonance in AuNPs, while recording their resultant phase signatures. To check the potential of the AuNPs as interferometric cellular labels, they were conjugated to a glass coverslip and excited with a laser at a wavelength corresponding to their absorption spectral peak. We then acquired an image sequence of the sample phase profile in time without the need for lateral scanning, and analyzed the entire field of view using a Fourier analysis, creating a map of the locations of the AuNPs. We obtained a strong PT signal at AuNPs central locations, exponentially dependent on the distance from their centers. This enabled identification of the central locations of the AuNPs in the chosen field of view. Moreover, these PT signals had shown a linear relation to the illumination intensity, distinguishing them from background noise and out-of-focus particles. To the best of our knowledge, we are the first to record wide-field interferometric PT signals at the subcellular level without the need of total-internal-reflection prisms or scanning.

Turko, Nir A.; Peled, Ania; Shaked, Natan T.

2013-02-01

264

UVUDF: Ultraviolet Imaging of the Hubble Ultra Deep Field with Wide-Field Camera 3  

NASA Astrophysics Data System (ADS)

We present an overview of a 90 orbit Hubble Space Telescope treasury program to obtain near-ultraviolet imaging of the Hubble Ultra Deep Field using the Wide Field Camera 3 UVIS detector with the F225W, F275W, and F336W filters. This survey is designed to: (1) investigate the episode of peak star formation activity in galaxies at 1 < z < 2.5; (2) probe the evolution of massive galaxies by resolving sub-galactic units (clumps); (3) examine the escape fraction of ionizing radiation from galaxies at z ~ 2-3; (4) greatly improve the reliability of photometric redshift estimates; and (5) measure the star formation rate efficiency of neutral atomic-dominated hydrogen gas at z ~ 1-3. In this overview paper, we describe the survey details and data reduction challenges, including both the necessity of specialized calibrations and the effects of charge transfer inefficiency. We provide a stark demonstration of the effects of charge transfer inefficiency on resultant data products, which when uncorrected, result in uncertain photometry, elongation of morphology in the readout direction, and loss of faint sources far from the readout. We agree with the STScI recommendation that future UVIS observations that require very sensitive measurements use the instrument's capability to add background light through a "post-flash." Preliminary results on number counts of UV-selected galaxies and morphology of galaxies at z ~ 1 are presented. We find that the number density of UV dropouts at redshifts 1.7, 2.1, and 2.7 is largely consistent with the number predicted by published luminosity functions. We also confirm that the image mosaics have sufficient sensitivity and resolution to support the analysis of the evolution of star-forming clumps, reaching 28-29th magnitude depth at 5? in a 0.''2 radius aperture depending on filter and observing epoch. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are #12534.

Teplitz, Harry I.; Rafelski, Marc; Kurczynski, Peter; Bond, Nicholas A.; Grogin, Norman; Koekemoer, Anton M.; Atek, Hakim; Brown, Thomas M.; Coe, Dan; Colbert, James W.; Ferguson, Henry C.; Finkelstein, Steven L.; Gardner, Jonathan P.; Gawiser, Eric; Giavalisco, Mauro; Gronwall, Caryl; Hanish, Daniel J.; Lee, Kyoung-Soo; de Mello, Duilia F.; Ravindranath, Swara; Ryan, Russell E.; Siana, Brian D.; Scarlata, Claudia; Soto, Emmaris; Voyer, Elysse N.; Wolfe, Arthur M.

2013-12-01

265

Probing other solar systems with current and future adaptive optics  

SciTech Connect

Over the past decade, the study of extrasolar planets through indirect techniques--primarily Doppler measurements--has revolutionized our understanding of other solar systems. The next major step in this field will be the direct detection and characterization, via imaging and spectroscopy, of the planets themselves. To achieve this, we must separate the light from the faint planet from the extensive glare of its parent star. We pursued this goal using the current generation of adaptive optics (AO) systems on large ground-based telescopes, using infrared imaging to search for the thermal emission from young planets and developing image processing techniques to distinguish planets from telescope-induced artifacts. Our new Angular Differential Imaging (ADI) technique, which uses the sidereal rotation of the Earth and telescope, is now standard for ground-based high-contrast imaging. Although no young planets were found in our surveys, we placed the strongest limits yet on giant planets in wide orbits (>30 AU) around young stars and characterized planetary companion candidates. The imaging of planetary companions on solar-system-like scales (5-30 AU) will require a new generation of advanced AO systems that are an order of magnitude more powerful than the LLNL-built Keck AO system. We worked to develop and test the key technologies needed for these systems, including a spatially-filtered wavefront sensor, efficient and accurate wavefront reconstruction algorithms, and precision AO wavefront control at the sub-nm level. LLNL has now been selected by the Gemini Observatory to lead the construction of the Gemini Planet Imager, a $24M instrument that will be the most advanced AO system in the world.

Macintosh, B; Marois, C; Phillion, D; Poyneer, L; Graham, J; Zuckerman, B; Gavel, D; Veran, J; Wilhelmsen-Evans, J; Mellis, C

2008-09-08

266

The wide-field Fourier spectroscopic-imaging of the radiation heat from the object itself in the middle infrared region for the health monitoring  

NASA Astrophysics Data System (ADS)

We are aiming at the realization of the wide-field spectroscopic-imaging-sensor that is available for the health monitoring or the plant factory. Conventionally, the body temperature is measured by the thermography as a total intensity of the middle infrared radiation. We are trying to analyze the spectroscopic characteristics of the radiation heat from the human body in detail to measure the blood glucose or the moisture-retaining properties of the human skin. The proposed imaging-type 2-dimensional Fourier spectroscopy can measure the radiation heat from the object itself with the wide field of view and the wide wavelength-band. In this proposed method, we install the phase-shifter on the optical Fourier-transform-plane of the imaging optics to give the arbitrary phase-shift to the half flux of the object beams. Thus, the interferogram can be formed on the imaging plane in each bright point by the phase-shift interference-phenomena between the object beams that are emitted from the each corresponding bright point on the objective surface. In this report, we mention the feasibility results of the wide-field spectroscopic-imaging using the black body for the basic optical evaluation and the house plants for measuring the glucose distribution with the infrared camera(wavelength: 8?m-14?m).

Qi, Wei; Takuma, Takashi; Inui, Asuka; Tsutsumi, Ryosuke; Yuzuriha, Takehiko; Kagiyama, Hiroyasu; Kojima, Daisuke; Nishiyama, Akira; Ishimaru, Ichirou

2012-02-01

267

Optical cavity and future style of high-power fiber lasers  

Microsoft Academic Search

Possible designs of high power fiber lasers are discussed in this paper related to the future power delivery system in laser material processing factories. The performance of high power fiber lasers is analyzed using basic equations and optical parameters of laser cavities. High efficiency operation of 73% was demonstrated by clad pumping scheme using homogeneous absorption regime of Nd3+-doped rectangular

Ken-Ichi Ueda

1998-01-01

268

Wide-field fast-scanning photoacoustic microscopy based on a water-immersible MEMS scanning mirror  

NASA Astrophysics Data System (ADS)

By offering images with high spatial resolution and unique optical absorption contrast, optical-resolution photoacoustic microscopy (OR-PAM) has gained increasing attention in biomedical research. Recent developments in OR-PAM have improved its imaging speed, but have to sacrifice either the detection sensitivity or field of view or both. We have developed a wide-field fast-scanning OR-PAM by using a water-immersible microelectromechanical systems (MEMS) scanning mirror (MEMS-OR-PAM). In MEMS-OR-PAM, the optical and acoustic beams are confocally configured and simultaneously steered, which ensures the uniform detection sensitivity. A B-scan imaging speed as high as 400 Hz can be achieved over a 3 mm scanning range. Using the system, we imaged the flow dynamics of both red blood cells and carbon particles in a mouse ear in vivo. Presented results show that MEMS-OR-PAM could be a powerful tool for studying highly dynamic and time-sensitive biological phenomena.

Yao, Junjie; Huang, Chih-Hsien; Wang, Lidai; Yang, Joon-Mo; Gao, Liang; Maslov, Konstantin I.; Zou, Jun; Wang, Lihong V.

2012-08-01

269

Wide-field fast-scanning photoacoustic microscopy based on a water-immersible MEMS scanning mirror  

PubMed Central

Abstract. By offering images with high spatial resolution and unique optical absorption contrast, optical-resolution photoacoustic microscopy (OR-PAM) has gained increasing attention in biomedical research. Recent developments in OR-PAM have improved its imaging speed, but have to sacrifice either the detection sensitivity or field of view or both. We have developed a wide-field fast-scanning OR-PAM by using a water-immersible microelectromechanical systems (MEMS) scanning mirror (MEMS-OR-PAM). In MEMS-OR-PAM, the optical and acoustic beams are confocally configured and simultaneously steered, which ensures the uniform detection sensitivity. A B-scan imaging speed as high as 400 Hz can be achieved over a 3 mm scanning range. Using the system, we imaged the flow dynamics of both red blood cells and carbon particles in a mouse ear in vivo. Presented results show that MEMS-OR-PAM could be a powerful tool for studying highly dynamic and time-sensitive biological phenomena.

Yao, Junjie; Huang, Chih-Hsien; Wang, Lidai; Yang, Joon-Mo; Gao, Liang; Maslov, Konstantin I.; Zou, Jun; Wang, Lihong V.

2012-01-01

270

Optical Tweezers and Optical Trapping Improved for Future Automated Micromanipulation and Characterization  

NASA Technical Reports Server (NTRS)

Optical trap arrays are being developed at the NASA Glenn Research Center for holding, manipulating, and optically interrogating arrays of nanotube sensors. The trap arrays, for example, might be used to arrange arrays of chemical sensors for insertion onto a chip in liquid, air, and vacuum environments. Neural-network-controlled spatial light modulators (SLMs) are to generate and control the trap positions and trap profiles in three dimensions.

Wrbanek, Susan Y.; Decker, Arthur J.

2005-01-01

271

Wavelength routing and optical burst switching in the design of future optical network architectures  

Microsoft Academic Search

Wavelength-routed optical network (WRON) architectures potentially simplify routing and processing functions in high-capacity, high-bit rate WDM optical networks. With the inherent low latency these are relatively easy to design with a number of efficient routing and wavelength assignment protocols proposed to date. However, the pressure to optimise network resources and protocols for IP traffic has focused attention on network architectures

Polina Bayvel

2001-01-01

272

Optical Packet and Burst Switching Technologies for the Future Photonic Internet  

NASA Astrophysics Data System (ADS)

This paper reviews advanced optical burst switching (OBS) and optical packet switching (OPS) technologies and discusses their roles in the future photonic Internet. Discussions include optoelectronic and optical systems technologies as well as systems integration into viable network elements (OBS and OPS routers). Optical label switching (OLS) offers a unified multiple-service platform with effective and agile utilization of the available optical bandwidth in support of voice, data, and multimedia services on the Internet Protocol. In particular, OLS routers with wavelength routing switching fabrics and parallel optical labeling allow forwarding of asynchronously arriving variable-length packets, bursts, and circuits. By exploiting contention resolution in wavelength, time, and space domains, the OLS routers can achieve high throughput without resorting to a store-and-forward method associated with large buffer requirements. Testbed demonstrations employing OLS edge routers show high-performance networking in support of multimedia and data communications applications over the photonic Internet with optical packets and bursts switched directly at the optical layer.

Ben Yoo, S. J.

2006-12-01

273

Whole-cell-analysis of live cardiomyocytes using wide-field interferometric phase microscopy  

PubMed Central

We apply wide-field interferometric microscopy techniques to acquire quantitative phase profiles of ventricular cardiomyocytes in vitro during their rapid contraction with high temporal and spatial resolution. The whole-cell phase profiles are analyzed to yield valuable quantitative parameters characterizing the cell dynamics, without the need to decouple thickness from refractive index differences. Our experimental results verify that these new parameters can be used with wide field interferometric microscopy to discriminate the modulation of cardiomyocyte contraction dynamics due to temperature variation. To demonstrate the necessity of the proposed numerical analysis for cardiomyocytes, we present confocal dual-fluorescence-channel microscopy results which show that the rapid motion of the cell organelles during contraction preclude assuming a homogenous refractive index over the entire cell contents, or using multiple-exposure or scanning microscopy.

Shaked, Natan T.; Satterwhite, Lisa L.; Bursac, Nenad; Wax, Adam

2010-01-01

274

Wide Field Infrared Survey Telescope [WFIRST]: Telescope Design and Simulated Performance  

NASA Technical Reports Server (NTRS)

The ASTRO2010 Decadal Survey proposed multiple missions with NIR focal planes and 3 mirror wide field telescopes in the 1.5m aperture range. None of them would have won as standalone missions WFIRST is a combination of these missions, created by Astro 2010 committee. WFIRST Science Definition Team (SDT) tasked to examine the design. Project team is a GSFC-JPL-Caltech collaboration. This interim mission design is a result of combined work by the project team with the SDT.

Goullioud, R.; Content, D. A.; Kuan, G. M.; Moore, J. D.; Chang, Z.; Sunada, E. T.; Villalvazo, J.; Hawk, J. P.; Armani, N. V.; Johnson, E. L.; Powell, C. A.

2012-01-01

275

Sensors for the Hubble Space Telescope wide field and planetary cameras (1 and 2)  

NASA Technical Reports Server (NTRS)

The technology of the wide field planetary camera (WFPC-2) CCD technology is examined with reference to the WFPC-1 experience. Strategies are presented for elimination of quantum efficiency (QE) hysteresis and implementation of maintenance-free QE stability, improved far-UV performance, on-orbit photometric calibrations, refinements in CCD electronics, and anticipated CCD particle radiation effects. Absorption depth vs. wavelength in silicon and a cross section of the CCD membrane are shown.

Trauger, John T.

1990-01-01

276

Electronic Still Camera view of Aft end of Wide Field/Planetary Camera in HST  

NASA Technical Reports Server (NTRS)

A close-up view of the aft part of the Wide Field/Planetary Camera (WF/PC2) installed on the Hubble Space Telescope (HST) was photographed with the Electronic Still Camera (ESC) from inside Endeavour's cabin as Astronaut F. Story Musgrave and Jeffrey A. Hoffman moved it from its stowage position onto the giant telescope. Electronic still photography is technology which provides the means for a handheld camera to electronically capture and digitize an image with resolution approaching film quality.

1993-01-01

277

Hubble Space Telescope: Wide field and planetary camera instrument handbook. Version 2.1  

NASA Technical Reports Server (NTRS)

An overview is presented of the development and construction of the Wide Field and Planetary Camera (WF/PC). The WF/PC is a duel two dimensional spectrophotometer with rudimentary polarimetric and transmission grating capabilities. The instrument operates from 1150 to 11000 A with a resolution of 0.1 arcsec per pixel or 0.043 arcsec per pixel. Data products and standard calibration methods are briefly summarized.

Griffiths, Richard (editor)

1990-01-01

278

Defocused wide field fluorescence imaging of single CdSe/ZnS quantum dots  

NASA Astrophysics Data System (ADS)

Within this Letter, we demonstrate the application of defocused wide field fluorescence imaging to single CdSe/ZnS core shell quantum dots to obtain information on their orientation as well as on their transition moment. The emission intensity patterns obtained by the defocused imaging are compared to numerical calculations and reveal, that most of the quantum dots studied, possess an elliptical 2D transition moment, in contrast to the generally assumed circular 2D transition moment.

Schuster, Roman; Barth, Michael; Gruber, Achim; Cichos, Frank

2005-09-01

279

Wide-field photon counting fluorescence lifetime imaging microscopy: application to photosynthesizing systems  

Microsoft Academic Search

Fluorescence lifetime imaging microscopy (FLIM) is a technique that visualizes the excited state kinetics of fluorescence\\u000a molecules with the spatial resolution of a fluorescence microscope. We present a scanningless implementation of FLIM based\\u000a on a time- and space-correlated single photon counting (TSCSPC) method employing a position-sensitive quadrant anode detector\\u000a and wide-field illumination. The standard time-correlated photon counting approach leads to

Zden?k Petrášek; Hann-Jörg Eckert; Klaus Kemnitz

2009-01-01

280

Precision radial velocity followup of candidates showing velocity variability in the Sloan ET wide field survey  

Microsoft Academic Search

We propose to follow up potential exoplanet candidates by obtaining high precision Doppler radial velocity measurements using the HRS instrument on the HET. The candidates stars have been observed using a prototype wide field multi-object radial velocity instrument at the Sloan 2.5m telescope. This instrument is a fixed delay interferometer based on the design of the Kitt Peak ET instrument

Suvrath Mahadevan; Jian Ge; Julian van Eyken; Stephen Kane; Scott Fleming; Greg Henry

2007-01-01

281

A Wide Field-of-view Head Mounted Projective Display using Hyperbolic Half-silvered Mirrors  

Microsoft Academic Search

ABSTRACT The development ,of a ,wide ,field-of-view (FOV) head mounted display (HMD) has been a technological ,challenge for decades. Previous HMDs tackled this problem,using multiple display units (tiling) or multiple,curved mirrors. The former approach,tends to beexpensive and heavy, whereas the latter approach tends to suffer from image ,distortion and a small ,exit pupil. In order to provide a wide FOV

Kiyoshi Kiyokawa

2007-01-01

282

Wide-field all-sky monitor for X-ray astronomy  

NASA Astrophysics Data System (ADS)

The concept of using a pinhole camera as wide field-of-view detector for an X-ray all-sky monitor was first proposed by S. Holt and W. Priedhorsky in 1987 [1]. The hardware for such a monitor is ready to be launched. Here we discuss scientific tasks for such an experiment, its main parameters, and possibilities to install it on platforms/satellites of different types.

Borozdin, Konstantin N.; Priedhorsky, William C.; Arefiev, Vadim A.; Kaniovsky, Alexander S.; Black, Kevin; Brandt, Søren

1999-12-01

283

Image Formation in Wide-Field Microscopes Based on Leakage of Surface Plasmon-Coupled Fluorescence  

Microsoft Academic Search

A proof-of-concept imaging technique that combines the advantages of wide-field surface plasmon, leakage radiation, and total internal reflection fluorescence microscopy methods is presented. High-contrast non-scanning images with subwavelength resolution of patterned and homogeneous samples coated with a fluorescent material were demonstrated. We show that the image formed in the back focal plane of the objective lens can be reconstructed from

S. P. Frisbie; C. F. Chesnutt; M. E. Holtz; A. Krishnan; L. Grave de Peralta; A. A. Bernussi

2009-01-01

284

Wide field-of-view single-mode-fiber coupled laser communication terminal  

NASA Astrophysics Data System (ADS)

This paper describes the design of a wide field-of-view single-mode-fiber coupled free space laser communication terminal which has mutual beacon tracking system using a commercially available fast steering mirror. Using the terminals, we tried a low power laser beam transmission experiment over 500-m distance using a 1064 nm wavelength. This paper also reports the experimental results of terminal performance as well as propagation characteristics.

Arimoto, Yoshinori; Yoshida, Hiroyuki; Kisara, Katsuto

2013-03-01

285

Galaxy cluster searches based on photometric redshifts in the four CFHTLS Wide fields  

NASA Astrophysics Data System (ADS)

Context. Cosmological parameters can be constrained by counting clusters of galaxies as a function of mass and redshift and by considering regions of the sky sampled as deeply and as homogeneously as possible. Aims: Several methods for detecting clusters in large imaging surveys have been developed, among which the one used here, which is based on detecting structures. This method was first applied to the Canada France Hawaii Telescope Legacy Survey (CFHTLS) Deep 1 field by Mazure et al. (2007, A&A, 467, 49), then to all the Deep and Wide CFHTLS fields available in the T0004 data release by Adami et al. (2010, A&A, 509, A81). The validity of the cluster detection rate was estimated by applying the same procedure to galaxies from the Millennium simulation. Here we use the same method to analyse the full CFHTLS Wide survey, based on the T0006 data release. Methods: Our method is based on the photometric redshifts computed with Le Phare for all the galaxies detected in the Wide fields, limited to magnitudes z' ? 22.5. We constructed galaxy density maps in photometric redshift bins of 0.1 based on an adaptive kernel technique, detected structures with SExtractor at various detection levels, and built cluster catalogues by applying a minimal spanning tree algorithm. Results: In a total area of 154 deg2, we have detected 4061 candidate clusters at 3? or above (6802 at 2? and above), in the redshift range 0.1 ? z ? 1.15, with estimated mean masses between 1.3 × 1014 and 12.6 × 1014 M?. This catalogue of candidate clusters will be available at the CDS. We compare our detections with those made in various CFHTLS analyses with other methods. By stacking a subsample of clusters, we show that this subsample has typical cluster characteristics (colour - magnitude relation, galaxy luminosity function). We also confirm that the cluster-cluster correlation function is comparable to the one obtained for other cluster surveys and analyse large-scale filamentary galaxy distributions. Conclusions: We have increased the number of known optical high-redshift cluster candidates by a large factor, an important step towards obtaining reliable cluster counts to measure cosmological parameters. The clusters that we detect behave as expected if they are located at the intersection of filaments by which they are fed. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based on data products produced at TERAPIX and the Canadian Astronomy Data Centre as part of the CFHT Legacy Survey, a collaborative project of the NRC and CNRS.The catalog of candidate clusters is available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/535/A65

Durret, F.; Adami, C.; Cappi, A.; Maurogordato, S.; Márquez, I.; Ilbert, O.; Coupon, J.; Arnouts, S.; Benoist, C.; Blaizot, J.; Edorh, T. M.; Garilli, B.; Guennou, L.; Le Brun, V.; Le Fèvre, O.; Mazure, A.; McCracken, H. J.; Mellier, Y.; Mezrag, C.; Slezak, E.; Tresse, L.; Ulmer, M. P.

2011-11-01

286

Three-reflections telescope proposal as flat-field anastigmat for wide field observations at Dome C  

NASA Astrophysics Data System (ADS)

It is now evident that the exceptional seeing at Dome C will allow, in the next years, to pursue astronomical programs with conditions better than at any other observatory in the world, and very close to space experiments. Considering a new type of wide-field telescope, particular astronomical programs could be well optimized for observations at Dome C such as surveys for the discovery and follow up of near-Earth asteroids, search for extra-solar planets using transit or micro-lensing events, and stellar luminosity variations. We propose to build a 1.5 2m class three-reflections telescope, with 1 1.5degree FOV, four times shorter than an equivalent Schmidt telescope, and providing a flat field without requiring a triplet- or quadruplet-lens corrector since its design is anastigmatic. We present the preliminary optical tests of such designs: MINITRUST1 and 2 are two 45cm identical prototypes based in France and Italy, and manufactured using active optics techniques.

Ferrari, M.; Lemaître, G.; Viotti, R.; La Padula, C.; Comte, G.; Blanc, M.; Boer, M.

287

Optic variables used to judge future ball arrival position in expert and novice soccer players.  

PubMed

Although many studies have looked at the perceptual-cognitive strategies used to make anticipatory judgments in sport, few have examined the informational invariants that our visual system may be attuned to. Using immersive interactive virtual reality to simulate the aerodynamics of the trajectory of a ball with and without sidespin, the present study examined the ability of expert and novice soccer players to make judgments about the ball's future arrival position. An analysis of their judgment responses showed how participants were strongly influenced by the ball's trajectory. The changes in trajectory caused by sidespin led to erroneous predictions about the ball's future arrival position. An analysis of potential informational variables that could explain these results points to the use of a first-order compound variable combining optical expansion and optical displacement. PMID:19304642

Craig, Cathy M; Goulon, Cédric; Berton, Eric; Rao, Guillaume; Fernandez, Laure; Bootsma, Reinoud J

2009-04-01

288

SIMULTANEOUS EXOPLANET CHARACTERIZATION AND DEEP WIDE-FIELD IMAGING WITH A DIFFRACTIVE PUPIL TELESCOPE  

SciTech Connect

High-precision astrometry can identify exoplanets and measure their orbits and masses while coronagraphic imaging enables detailed characterization of their physical properties and atmospheric compositions through spectroscopy. In a previous paper, we showed that a diffractive pupil telescope (DPT) in space can enable sub-{mu}as accuracy astrometric measurements from wide-field images by creating faint but sharp diffraction spikes around the bright target star. The DPT allows simultaneous astrometric measurement and coronagraphic imaging, and we discuss and quantify in this paper the scientific benefits of this combination for exoplanet science investigations: identification of exoplanets with increased sensitivity and robustness, and ability to measure planetary masses to high accuracy. We show how using both measurements to identify planets and measure their masses offers greater sensitivity and provides more reliable measurements than possible with separate missions, and therefore results in a large gain in mission efficiency. The combined measurements reliably identify potentially habitable planets in multiple systems with a few observations, while astrometry or imaging alone would require many measurements over a long time baseline. In addition, the combined measurement allows direct determination of stellar masses to percent-level accuracy, using planets as test particles. We also show that the DPT maintains the full sensitivity of the telescope for deep wide-field imaging, and is therefore compatible with simultaneous scientific observations unrelated to exoplanets. We conclude that astrometry, coronagraphy, and deep wide-field imaging can be performed simultaneously on a single telescope without significant negative impact on the performance of any of the three techniques.

Guyon, Olivier; Eisner, Josh A.; Angel, Roger; Woolf, Neville J. [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)] [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Bendek, Eduardo A.; Milster, Thomas D. [College of Optical Sciences, University of Arizona, Tucson, AZ 85721 (United States)] [College of Optical Sciences, University of Arizona, Tucson, AZ 85721 (United States); Ammons, S. Mark [Lawrence Livermore National Laboratory, Physics Division L-210, 7000 East Avenue, Livermore, CA 94550 (United States)] [Lawrence Livermore National Laboratory, Physics Division L-210, 7000 East Avenue, Livermore, CA 94550 (United States); Shao, Michael; Shaklan, Stuart; Levine, Marie; Nemati, Bijan [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)] [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Martinache, Frantz [National Astronomical Observatory of Japan, Subaru Telescope, Hilo, HI 96720 (United States)] [National Astronomical Observatory of Japan, Subaru Telescope, Hilo, HI 96720 (United States); Pitman, Joe [Exploration Sciences, P.O. Box 24, Pine, CO 80470 (United States)] [Exploration Sciences, P.O. Box 24, Pine, CO 80470 (United States); Woodruff, Robert A. [Lockheed Martin, 2081 Evergreen Avenue, Boulder, CO 80304 (United States)] [Lockheed Martin, 2081 Evergreen Avenue, Boulder, CO 80304 (United States); Belikov, Ruslan, E-mail: guyon@naoj.org [NASA Ames Research Center, Moffett Field, CA 94035 (United States)] [NASA Ames Research Center, Moffett Field, CA 94035 (United States)

2013-04-10

289

Wide-field in vivo background free imaging by selective magnetic modulation of nanodiamond fluorescence.  

PubMed

The sensitivity and resolution of fluorescence-based imaging in vivo is often limited by autofluorescence and other background noise. To overcome these limitations, we have developed a wide-field background-free imaging technique based on magnetic modulation of fluorescent nanodiamond emission. Fluorescent nanodiamonds are bright, photo-stable, biocompatible nanoparticles that are promising probes for a wide range of in vitro and in vivo imaging applications. Our readily applied background-free imaging technique improves the signal-to-background ratio for in vivo imaging up to 100-fold. This technique has the potential to significantly improve and extend fluorescent nanodiamond imaging capabilities on diverse fluorescence imaging platforms. PMID:24761300

Sarkar, Susanta K; Bumb, Ambika; Wu, Xufeng; Sochacki, Kem A; Kellman, Peter; Brechbiel, Martin W; Neuman, Keir C

2014-04-01

290

Wide-field compact catadioptric telescope spanning 0.7-14 ?m wavelengths.  

PubMed

We present a wide-field compact f-1.2, f-1.6 effective illumination catadioptric telescope that spans the wavelengths 0.7-14.0 ?m. Such a telescope replaces several telescopes designed for different infrared bands, while having a track length shorter than most single-band telescopes. Incorporated with a suitable multiband focal plane array, many wavelength bands may be imaged simultaneously in the same instrument. We have constructed and tested prototypes of the telescopes and found the performance is near the predicted values. PMID:23842177

Marks, Daniel L; Hagen, Nathan; Durham, Mark; Brady, David J

2013-06-20

291

The Antarctica Wide-field High-resolution Infrared Telescope (WHITE)  

NASA Astrophysics Data System (ADS)

What is a good astronomical site? It must be cold, dry, stable, dark. There is one site on Earth that qualifies : Antarctica. To make the best use of these characteristics, we propose a Wide-field (0.5-degree in diameter) High-resolution (~0.3 arcsec using GLAO from the ice), IR (0.8-5 ?m) 2.4-m TElescope (WHITE). WHITE will be dedicated to carrying out surveys: a deep extragalactic field over a few square degrees, a survey of the Magellanic Clouds. By adding one more year, WHITE would be able to add one kilo-degree survey.

Burgarella, Denis; Le Roux, Brice; Langlois, Maud; Lemaître, Gérard; Fusco, Thierry; Moretto, Gilberto; Ferrari, Marc

2008-08-01

292

Micrometeoroid Impacts on the Hubble Space Telescope Wide Field and Planetary Camera 2: Larger Particles  

NASA Technical Reports Server (NTRS)

The Wide Field and Planetary Camera 2 (WFPC2) was returned from the Hubble Space Telescope (HST) by shuttle mission STS-125 in 2009. In space for 16 years, the surface accumulated hundreds of impact features on the zinc orthotitanate paint, some penetrating through into underlying metal. Larger impacts were seen in photographs taken from within the shuttle orbiter during service missions, with spallation of paint in areas reaching 1.6 cm across, exposing alloy beneath. Here we describe larger impact shapes, the analysis of impactor composition, and the micrometeoroid (MM) types responsible.

Kearsley, A. T.; Grime, G. W.; Webb, R. P.; Jeynes, C.; Palitsin, V.; Colaux, J. L.; Ross, D. K.; Anz-Meador, P.; Liou, J. C.; Opiela, J.; Griffin, G. T.; Gerlach, L.; Wozniakiewicz, P. J.; Price, M. C.; Burchell, M. J.; Cole, M. J.

2014-01-01

293

Deconvolution of wide-field-of-view measurements of reflected solar radiation  

NASA Technical Reports Server (NTRS)

Wide-field-of-view (WFOV) radiometers have been flown as part of the Earth Radiation Budget instrument on the Nimbus 6 and 7 spacecraft and as part of the Earth Radiation Budget Experiment (ERBE) instruments aboard the ERBE spacecraft and also the NOAA 9 and 10 operational spacecraft. The measurement is the integral of the reflected solar flux distribution at the top of the earth-atmosphere system over the field-of-view of the radiometer. This paper develops the solution to this two-dimensional integral equation for the albedo distribution in terms of the measurements.

Smith, G. Louis; Rutan, David

1990-01-01

294

The TERAPIX Tool for the Reduction of Wide-Field Images  

NASA Astrophysics Data System (ADS)

TERAPIX (Traitement Élémentaire Réduction et Analyse des PIXels) is an astronomical data processing center located at IAP (Institut d'Astrophysique de Paris). TERAPIX is aimed to the processing of mosaics of wide-field images from CFH12K and MEGACAM at CFHT, WFI at ESO and OMEGACAM at VST: at present more than 2 Terabytes of disk space are available, as well as three COMPAQ workstations with EV5, EV6 and EV67 processors see http://www.terapix.iap.fr for more details

Radovich, M.; Mellier, Y.; Bertin, E.; Missonnier, G.; Didelon, P.; Morin, B.; Dantel-Fort, M.; McCracken, H.

295

Wide field-of-view lens-free fluorescent imaging on a chip  

PubMed Central

We demonstrate an on-chip fluorescent detection platform that can simultaneously image fluorescent micro-objects or labeled cells over an ultra-large field-of-view of 2.5 cm × 3.5 cm without the use of any lenses, thin-film filters and mechanical scanners. Such a wide field-of-view lensless fluorescent imaging modality, despite its limited resolution, might be very important for high-throughput screening applications as well as for detection and counting of rare cells within large-area microfluidic devices.

Coskun, Ahmet F.; Su, Ting-Wei

2010-01-01

296

Field testing the wide-field-of-view imaging spectrometer(WFIS)  

NASA Astrophysics Data System (ADS)

The Wide Field-of-view Imaging Spectrometer (WFIS), a high-performance pushbroom hyperspectral imager designed for atmospheric chemistry and aerosols measurement from an aircraft or satellite, underwent initial field testing in 2004. The results of initial field tests demonstrate the all-reflective instrument's imaging performance and the capabilities of data processing algorithms to render hyperspectral image cubes from the field scans. Further processing results in spectral and photographic imagery suitable for identification, analysis, and discrimination of subjects in the images. The field tests also reveal that the WFIS instrument is suited for other applications, including in situ imaging and geological remote sensing.

Haring, Robert E.; Pollock, Randy; Cross, Richard M.; Sutin, Brian M.

2004-11-01

297

On the design of wide-field x-ray telescopes  

NASA Astrophysics Data System (ADS)

X-ray telescopes having a relatively wide field-of-view and spatial resolution vs. polar off-axis angle curves much flatter than the parabolic dependence characteristic of Wolter I designs are of great interest for surveys of the X-ray sky and potentially for study of the Sun's X-ray emission. We discuss the various considerations affecting the design of such telescopes, including the possible use of polynomial mirror surface prescriptions, a method of optimizing the polynomial coefficients, scaling laws for mirror segment length vs. intersection radius, the loss of on-axis spatial resolution, and the positioning of focal plane detectors.

Elsner, Ronald F.; O'Dell, Stephen L.; Ramsey, Brian D.; Weisskopf, Martin C.

2009-08-01

298

Cryogenic Optical Performance of a Lightweighted Mirror Assembly for Future Space Astronomical Telescopes: Correlating Optical Test Results and Thermal Optical Model  

NASA Technical Reports Server (NTRS)

A 43cm diameter stacked core mirror demonstrator was interferometrically tested at room temperature down to 250 degrees Kelvin for thermal deformation. The 2.5m radius of curvature spherical mirror assembly was constructed by low temperature fusing three abrasive waterjet core sections between two CNC pocket milled face sheets. The 93% lightweighted Corning ULE® mirror assembly represents the current state of the art for future UV, optical, near IR space telescopes. During the multiple thermal test cycles, test results of interferometric test, thermal IR images of the front face were recorded in order to validate thermal optical model.

Eng, Ron; Arnold, William R.; Baker, Marcus A.; Bevan, Ryan M.; Burdick, Gregory; Effinger, Michael R.; Gaddy, Darrell E.; Goode, Brian K.; Hanson, Craig; Hogue, William D.; Kegley, Jeffrey R.; Kirk, Charlie; Maffett, Steven P.; Matthews, Gary W.; Siler, Richard D.; Smith, W. Scott; Stahl, H. Philip; Tucker, John M.; Wright, Ernest R.

2013-01-01

299

Cryogenic Optical Performance of a Light-weight Mirror Assembly for Future Space Astronomical Telescopes: Optical Test Results and Thermal Optical Model  

NASA Technical Reports Server (NTRS)

A 40 cm diameter mirror assembly was interferometrically tested at room temperature down to 250 degrees Kelvin for thermal deformation. The 2.5 m radius of curvature spherical mirror assembly was constructed by low temperature fusing three abrasive waterjet core sections between two face sheets. The 93% lightweighted Corning ULE mirror assembly represents the current state of the art for future UV, optical, near IR space telescopes. During the multiple thermal test cycles, test results of interferometric test, thermal IR images of the front face were recorded in order to validate thermal optical model.

Eng, Ron; Arnold, William; Baker, Markus A.; Bevan, Ryan M.; Carpenter, James R.; Effinger, Michael R.; Gaddy, Darrell E.; Goode, Brian K.; Kegley, Jeffrey R.; Hogue, William D.; Siler, Richard D.; Smith, W. Scott; Stahl. H. Philip; Tucker, John M.; Wright, Ernest R.; Kirk, Charles S.; Hanson, Craig; Burdick, Gregory; Maffett, Steven

2013-01-01

300

Outer density profiles of 19 Galactic globular clusters from deep and wide-field imaging  

NASA Astrophysics Data System (ADS)

Using deep photometric data from Wide Field Camera at the Isaac Newton Telescope and Wide Field Imager at the ESO 2.2-m telescope we measure the outer number density profiles of 19 stellar clusters located in the inner region of the Milky Way halo (within a Galactocentric distance range of 10-30 kpc) in order to assess the impact of internal and external dynamical processes on the spatial distribution of stars. Adopting power-law fitting templates, with index -? in the outer region, we find that the clusters in our sample can be divided in two groups: a group of massive clusters (?105 M?) that has relatively flat profiles with 2.5 < ? < 4, and a group of low-mass clusters (?105 M?), with steep profiles (? > 4) and clear signatures of interaction with the Galactic tidal field. We refer to these two groups as 'tidally unaffected' and 'tidally affected', respectively. Our results also show a clear trend between the slope of the outer parts and the half-mass density of these systems, which suggests that the outer density profiles may retain key information on the dominant processes driving the dynamical evolution of globular clusters.

Carballo-Bello, Julio A.; Gieles, Mark; Sollima, Antonio; Koposov, Sergey; Martínez-Delgado, David; Peñarrubia, Jorge

2012-01-01

301

Astro-WISE Processing of Wide-field Images and Other Data  

NASA Astrophysics Data System (ADS)

Astro-WISE (Vriend et al. 2012) is the Astronomical Wide-field Imaging System for Europe (Valentijn et al. 2007). It is a scientific information system which consists of hardware and software federated over about a dozen institutes throughout Europe. It has been developed to exploit the ever increasing avalanche of data produced by astronomical surveys and data intensive scientific experiments in general. The demo explains the architecture of the Astro-WISE information system and shows the use of Astro-WISE interfaces. Wide-field astronomical images are derived from the raw image to the final catalog according to the user's request. The demo is based on the standard Astro-WISE guided tour, which can be accessed from the Astro-WISE website. The typical Astro-WISE data processing chain is shown, which can be used for data handling for a variety of different instruments, currently 14, including OmegaCAM, MegaCam, WFI, WFC, ACS/HST, etc.

Buddelmeijer, H.; Williams, O. R.; McFarland, J. P.; Belikov, A.

2012-09-01

302

Wide-field imaging and flow cytometric analysis of cancer cells in blood by fluorescent nanodiamond labeling and time gating.  

PubMed

Nanodiamonds containing high density ensembles of negatively charged nitrogen-vacancy (NV(-)) centers are promising fluorescent biomarkers due to their excellent photostability and biocompatibility. The NV(-) centers in the particles have a fluorescence lifetime of up to 20?ns, which distinctly differs from those (<10?ns) of cell and tissue autofluorescence, making it possible to achieve background-free detection in vivo by time gating. Here, we demonstrate the feasibility of using fluorescent nanodiamonds (FNDs) as optical labels for wide-field time-gated fluorescence imaging and flow cytometric analysis of cancer cells with a nanosecond intensified charge-coupled device (ICCD) as the detector. The combined technique has allowed us to acquire fluorescence images of FND-labeled HeLa cells in whole blood covered with a chicken breast of ~0.1-mm thickness at the single cell level, and to detect individual FND-labeled HeLa cells in blood flowing through a microfluidic device at a frame rate of 23?Hz, as well as to locate and trace FND-labeled lung cancer cells in the blood vessels of a mouse ear. It opens a new window for real-time imaging and tracking of transplanted cells (such as stem cells) in vivo. PMID:24994610

Hui, Yuen Yung; Su, Long-Jyun; Chen, Oliver Yenjyh; Chen, Yit-Tsong; Liu, Tzu-Ming; Chang, Huan-Cheng

2014-01-01

303

Wide-field imaging and flow cytometric analysis of cancer cells in blood by fluorescent nanodiamond labeling and time gating  

PubMed Central

Nanodiamonds containing high density ensembles of negatively charged nitrogen-vacancy (NV?) centers are promising fluorescent biomarkers due to their excellent photostability and biocompatibility. The NV? centers in the particles have a fluorescence lifetime of up to 20?ns, which distinctly differs from those (<10?ns) of cell and tissue autofluorescence, making it possible to achieve background-free detection in vivo by time gating. Here, we demonstrate the feasibility of using fluorescent nanodiamonds (FNDs) as optical labels for wide-field time-gated fluorescence imaging and flow cytometric analysis of cancer cells with a nanosecond intensified charge-coupled device (ICCD) as the detector. The combined technique has allowed us to acquire fluorescence images of FND-labeled HeLa cells in whole blood covered with a chicken breast of ~0.1-mm thickness at the single cell level, and to detect individual FND-labeled HeLa cells in blood flowing through a microfluidic device at a frame rate of 23?Hz, as well as to locate and trace FND-labeled lung cancer cells in the blood vessels of a mouse ear. It opens a new window for real-time imaging and tracking of transplanted cells (such as stem cells) in vivo.

Hui, Yuen Yung; Su, Long-Jyun; Chen, Oliver Yenjyh; Chen, Yit-Tsong; Liu, Tzu-Ming; Chang, Huan-Cheng

2014-01-01

304

A payload-centric integration and test approach on the Wide-field Infrared Survey Explorer Mission  

NASA Astrophysics Data System (ADS)

NASA's Wide-field Infrared Survey Explorer (WISE) mission was successfully launched on December 14, 2009. All spacecraft subsystems and the single instrument consisting of four imaging bands from 3.4 to 22 microns, a 40 cm afocal telescope, reimaging optics, and a two-stage solid hydrogen cryostat have performed nominally on orbit, enabling the trouble-free survey of the entire infrared sky. Among the many factors that contributed to the WISE post-launch success is the thorough pre-launch system integration and test (I&T) approach tailored to the cryogenic payload. The simple and straightforward interfaces between the spacecraft and the payload allowed the payload to be fully tested prior to integration with the spacecraft. A payload high-fidelity thermal, mass and dynamic simulator allowed the spacecraft I&T to proceed independently through the system-level thermal vacuum test and random vibration test. A payload electrical simulator, a high-rate data processor and a science data ingest processor enabled very early end-to-end data flow and radio-frequency testing using engineering model payload electronics and spacecraft avionics, which allowed engineers to identify and fix developmental issues prior to building flight electronics. This paper describes in detail the WISE I&T approach, its benefits, challenges encountered and lessons learned.

Liu, Fengchuan; Abid, Mohamed; Duval, Valerie; Eisenhardt, Peter; Elwell, John; Heinrichsen, Ingolf; Irace, William R.; Lapointe, Jason; Larsen, Mark; Shannon, Mark; Taylor, Nicholas; Wright, Edward

2010-08-01

305

Optical metrology of micro- and nanostructures at PTB: status and future developments  

NASA Astrophysics Data System (ADS)

Today, various types of high resolution dimensional metrology instrumentation are in use for a quantitative characterisation of micro- and nanostructures. Although sophisticated ultra high resolution microscopic techniques like SEM and AFM are available, optical methods like microscopy and scatterometry are still of interest and are important because they are non-destructive, fast and have a good in-line capability. At PTB different optical tools are used for high-resolution metrology. Our standard instrument for CD metrology is a special UV transmission microscope. A new 193nm microscope is currently under development which will meet future requirements at least for the 32nm node as specified in the ITRS roadmap. A special alternating grazing incidence dark field microscope is used to measure the width of single features down to 100nm. For grating structures, we developed an optical diffractometer for pitch calibrations with an uncertainty down to 10 pm. Recently we realised a DUV scatterometer and ellipsometer capable to measure accurately CD, edge profile, layer thickness, and optical parameters. A versatile EUV scatterometer can be used to characterise absorber structures e. g. on EUV photomasks. For accurate measurements a thorough modelling on the basis of rigorous diffraction calculation is essential, which accounts for both polarisation effects and the 3D geometry of the structures. We use the rigorous coupled wave analysis (RCWA) method and the finite elements (FEM) method. We present an overview of PTB's current and future activities in optical high-resolution metrology and how these systems compare to ultra-high resolution microscopy like SEM or AFM.

Bodermann, Bernd; Buhr, Egbert; Ehret, Gerd; Scholze, Frank; Wurm, Matthias

2008-10-01

306

Lessons Learned from the Wide Field Camera 3 TV1 and TV2 Thermal Vacuum Test Campaigns  

NASA Technical Reports Server (NTRS)

The Wide Field Camera 3 (WFC3) instrument has undergone two complete thermal vacuum tests (TV1 and TV2), during which valuable lessons were learned regarding test configuration, test execution, model capabilities, and modeling practices. The very complex thermal design of WFC3 produced a number of challenging aspects to ground testing with numerous ThermoElectric Coolers and heat pipes, not all of which were functional. Lessons learned during TV1 resulted in significant upgrades to the model capabilities and a change in the test environment approach for TV2. These upgrades proved invaluable during TV2 when pretest modeling assumptions proved to be false. Each of the lessons learned relate to one of two following broad statements: 1. Ensure the design can be tested and that the effect of non-flight like conditions is well understood, particularly with respect to non passive devices (TECs, Heat Pipes, etc) 2. Ensure that the model is sufficiently detailed and is capable of predicting off-nominal behavior and the power dissipation of any thermal devices, especially TECs This paper outlines a number of the lessons learned over these two test campaigns with respect to the thermal design, model, and test configuration and presents recommendations for future tests.

Peabody, Hume; Stavely, Richard; Bast, William

2008-01-01

307

Future Optical Access Network and Spectral M-Ary ASK OCDM as Its Key Technology  

NASA Astrophysics Data System (ADS)

This paper presents spectral multi-level (M-ary) amplitude shift keying (ASK) optical code-division-multiplexing (OCDM) as a key technology for future optical access network. A novel transmitter configuration to achieve flexible scalability that is required in future optical access network is proposed. The transmitter employs pre-biasing circuits and dummy data input. Pre-biasing circuits enable us to achieve high tolerance to multiple access interference by compensating for the nonlinearity of the M-ary ASK and increase the number of multiplexed binary data streams. By inputting the dummy data into the transmitter so that the total number of multiplexed binary data streams including those that actually accommodate users/services and the dummy streams remains constant, the number of users/services can be increased up to the total number of data streams without changing the parameters for pre-biasing. Therefore, the proposed transmitter can flexibly enhance the scalability of the spectral M-ary ASK OCDM. The formulas for calculating the bit error rate characteristics are described when using the conventional and proposed transmitters. The feasibility of the proposed transmitter is verified theoretically using the established formulas.

Kaneko, Shin; Miki, Noriki; Kimura, Hideaki; Hadama, Hisaya

308

Present performance and future directions in two-photon addressed write once read many (WORM) volumetric optical disk storage systems  

NASA Astrophysics Data System (ADS)

Current performance in two-photon WORM volumetric write once read many data storage systems is presented and future directions discussed. Influence of numerical aperture in a 3-D multi-layer optical data storage system is analyzed.

Esener, Sadik C.; Walker, Edwin P.; Zhang, Yi; Dvornikov, Alexander S.; Rentzepis, Peter M.

2003-12-01

309

A Very Wide-Field Hybrid (Focusing/Coded Mask) X-Ray Telescope Concept  

NASA Astrophysics Data System (ADS)

The success of Swift at detecting and positioning variable hard X-ray sources, most notably gamma-ray bursts (GRBs), demonstrates that investigations with a very wide field telescope should continue permanently, like the continuing search for supernovas, and its scope expanded. The softer X-ray band is likely to be an even richer arena in which to search for ever more distant GRBs. The X-ray component of their spectra will be enriched by the redshift especially at large distances where the redshift increases very rapidly with distance. Furthermore most GRBs are likely to have an X-ray afterglow, which a very wide field telescope would detect from its birth. Multiple X-ray afterglows can be studied simultaneously. Some GRB models predict that X-ray afterglows will be more numerous than GRBs because they are less narrowly beamed. In addition many other types of variable X-ray sources can be monitored even more effectively than by scanning instruments. There are three possible approaches to a very wide field X-ray telescope, a 2D coded mask like Swift, a 2D lobster-eye telescope, and a hybrid that is a lobster-eye telescope in one dimension and a coded mask in the other. For the same field of view and the same focal length all three could use the same detector system including an omni-directional gamma-ray detector. We offer reasons why the hybrid, which is composed of identical flat mirrors, is the best of the three. It has much less background from diffuse X-rays and known X-ray sources than the 2D coded mask, and has substantially more area and bandwidth than the 2D lobster-eye. While positions are expected to be an arc minute or better, a small number of the mirrors used to fabricate the hybrid can be configured as a KB telescope that when pointed refines positions to arc second precision.

Gorenstein, Paul

2011-09-01

310

A wide-field near-infrared camera and spectrograph for the Mt. Abu 1.2 m telescope  

NASA Astrophysics Data System (ADS)

We describe the design and optimization of a wide-field near-infrared camera and spectrograph (NICAS) for Mt Abu 1.2 m, f/13 Cassegrain telescope of Physical Research Laboratory. The principal science goals include photometric mapping of star forming regions and medium resolution spectroscopy of Young Stellar Objects, evolved stars and transient sources. The design goals are to achieve seeing-limited angular resolution in an un-vignetted field of view of ~ 8'x8' with 0.5" per pixel (of 18.5 ?m) on a HgCdTe 1024×1024 infrared array, requiring a two-fold Cassegrain focal reduction. In addition to the imaging, the instrument is required to have spectroscopic capability with a resolving power of 103 in the 0.85 - 2.5 ?m region, needing a dispersion of 1 nm per pixel. Finally, since our telescope has a moderate aperture, the throughput losses need to be minimized. The specifications are achieved by an optical design using 9 singlet lenses. Only those lens materials are chosen for which measured values are available for refractive indices at 77 K (detector operating temperature), changes of indices with temperature, and thermal coefficients of expansion. The design is optimized to give sharpest images at 77 K. The optical path is folded by 90° after collimation by a fold-mirror and re-imaged on the detector. The fold-mirror is replaced by a diffraction grating for spectrograph mode. In order to minimize the reflection losses, all the lenses will be anti-reflection coated for the full operating wavelength range. Details of the design are presented.

Anandarao, Boddapati; Richardson, Eric Harvey; Chakraborty, Abhijit; Epps, Harland

2008-08-01

311

Monitoring AGNs and transient sources with the Wide Field X-ray Telescope  

NASA Astrophysics Data System (ADS)

The Wide Field X-ray Telescope (WFXT) is a proposed mission concept with a high survey speed, due to the combination of large field of view (FOV), effective area and sharp PSF across the whole FOV. A mission such as WFXT will detect a large number of variable and transient X-ray sources during its operating lifetime. We present estimates of the WFXT capabilities in the time domain, allowing to study variability of thousand of AGNs with significant detail, as well as to constrain the rates and properties of hundreds of X-ray Flashes/faint GRBs, Tidal Disruption Events, ULXs, Type-I bursts etc. The planned WFXT extragalactic surveys would thus allow to trace variable and transient X-ray populations over cosmological volumes.

Paolillo, M.; Pinto, C.; Allevato, V.; de Martino, D.; della Valle, M.; Papadakis, I.; WFXT Collaboration

312

Wide-field fluorescence lifetime imaging with multi-anode detectors.  

PubMed

Fluorescence lifetime imaging microscopy (FLIM) has become a powerful and widely used tool to monitor inter- and intramolecular dynamics of fluorophore-labeled proteins inside living cells.Here, we present recent achievements in the construction of a positional sensitive wide-field single-photon counting detector system to measure fluorescence lifetimes in the time domain and demonstrate its usage in FRET applications.The setup is based on a conventional fluorescence microscope equipped with synchronized short-pulse lasers that illuminate the entire field of view at minimal invasive intensities, thereby enabling long-term experiments of living cells. The system is capable to acquire single-photon counting images and measures directly the transfer rate of fast photophysical processes as, for instance, FRET, in which it can resolve complex fluorescence decay kinetics. PMID:24108639

Hartig, Roland; Prokazov, Yury; Turbin, Evgeny; Zuschratter, Werner

2014-01-01

313

Wide-field computational color imaging using pixel super-resolved on-chip microscopy  

PubMed Central

Lens-free holographic on-chip imaging is an emerging approach that offers both wide field-of-view (FOV) and high spatial resolution in a cost-effective and compact design using source shifting based pixel super-resolution. However, color imaging has remained relatively immature for lens-free on-chip imaging, since a ‘rainbow’ like color artifact appears in reconstructed holographic images. To provide a solution for pixel super-resolved color imaging on a chip, here we introduce and compare the performances of two computational methods based on (1) YUV color space averaging, and (2) Dijkstra’s shortest path, both of which eliminate color artifacts in reconstructed images, without compromising the spatial resolution or the wide FOV of lens-free on-chip microscopes. To demonstrate the potential of this lens-free color microscope we imaged stained Papanicolaou (Pap) smears over a wide FOV of ~14 mm2 with sub-micron spatial resolution.

Greenbaum, Alon; Feizi, Alborz; Akbari, Najva; Ozcan, Aydogan

2013-01-01

314

The Wide Field/Planetary Camera 2 (WFPC-2) molecular adsorber  

NASA Technical Reports Server (NTRS)

A device has been developed at the Jet Propulsion Laboratory, California Institute of Technology, for the adsorption of contaminants inside a space instrument during flight. The molecular adsorber was developed for use on the Wide Field Planetary Camera 2, and it has been shown to perform at its design specifications in the WFPC-2. The basic principle of the molecular adsorber is a zeolite-coated ceramic honeycomb. The arrangement is efficient for adsorption and also provides the needed rigidity to retain the special zeolite coating during the launch vibrational environment. The adsorber, on other forms, is expected to be useful for all flight instruments sensitive to internal sources of contamination. Typically, some internal contamination is unavoidable. A common design solution is to increase the venting to the exterior. However, for truly sensitive instruments, the external contamination environment is more severe. The molecular adsorber acts as a one-way vent to solve this problem. Continued development is planned for this device.

Barengoltz, Jack; Moore, Sonya; Soules, David; Voecks, Gerald

1995-01-01

315

The Zvenigorod Astronomical Plate Collection Presented in the Wide-Field Plate Database  

NASA Astrophysics Data System (ADS)

The results of the plate cataloging and digitization in the Zvenigorod Observatory are described. The observational material was obtained in the period 1972 - 2005 with the 40 cm Carl Zeiss astrograph (F=200 cm, field size 8x8 sq. deg., scale 100 arcsec/mm). The archive includes at present 3703 plates observations in the northern hemisphere mainly for mapping the sky according to the FON program. In addition, other objects as asteroids, minor planets, Pluto, Mars, etc. were observed too. A part of the archive is scanned already, as well as original observational logbooks. These results are included in the Wide-Field Plate Database in Sofia (www.skyarchive.org) and described in the site of the Institute of Astronomy, RAN (http://www.inasan.ru/ rus/scan/).

Vereshchagin, S. V.; Chupina, N. V.; Osipenko, V. P.; Dluzhnevskaya, O. B.; Tsvetkov, M. K.

2012-01-01

316

Wide field-of-view digital night vision head-mounted display  

NASA Astrophysics Data System (ADS)

SA Photonics has developed (with support from the Air Force Research Lab, the US Army and Vision Systems International) an innovative wide field of view digital night vision head mounted display (HMD). This HMD has an 80 degree field of view to greatly improve operator situational awareness. By using creating an all-digital system, we provide the capability to enhance and record night vision imagery, overlay symbology, and inset video from remote sensors, either mounted on the aircraft or on UAVs. This HMD has been designed with maximum pilot utility in mind, and is easily stowable without impacting center of gravity or maneuverability of the pilot's head within the cockpit. Because the sensors are digital, they can be located right above the pilot's eyes removing any hyperstereoopsis.

Browne, Michael P.

2011-05-01

317

A Powerful New Imager for HST: Performance and Early Science Results from Wide Field Camera 3  

NASA Technical Reports Server (NTRS)

Wide Field Camera 3 (WFC3) was installed into the Hubble Space Telescope during the highly successful Servicing Mission 4 in May, 2009. WFC3 offers sensitive, high resolution imaging over a broad wavelength range from the near UV through the visible to the near IR (200nm - 1700nm). Its capabilities in the near UV and near IR ends of that range represent particularly large advances vs. those of previous HST instruments. In this talk, I will review the purpose and design of the instrument, describe its performance in flight, and highlight some of the initial scientific results from the instrument, including its use in deep infrared surveys in search of galaxies at very high redshift, in investigations of the global processes of star formation in nearby galaxies, and in the study of the recent impact on Jupiter.

Kimble, Randy

2009-01-01

318

A mobile phone-based retinal camera for portable wide field imaging.  

PubMed

Digital fundus imaging is used extensively in the diagnosis, monitoring and management of many retinal diseases. Access to fundus photography is often limited by patient morbidity, high equipment cost and shortage of trained personnel. Advancements in telemedicine methods and the development of portable fundus cameras have increased the accessibility of retinal imaging, but most of these approaches rely on separate computers for viewing and transmission of fundus images. We describe a novel portable handheld smartphone-based retinal camera capable of capturing high-quality, wide field fundus images. The use of the mobile phone platform creates a fully embedded system capable of acquisition, storage and analysis of fundus images that can be directly transmitted from the phone via the wireless telecommunication system for remote evaluation. PMID:24344230

Maamari, Robi N; Keenan, Jeremy D; Fletcher, Daniel A; Margolis, Todd P

2014-04-01

319

Infrared wide field camera-spectrographs for a 2m-class telescope at Dome C  

NASA Astrophysics Data System (ADS)

We are exploring instrumental concepts of Near and Mid InfraRed (NIR, MIR) wide field camera-spectrographs for a 2 m-class telescope at Antarctica. Scientific drivers are star formation and very low mass objects. Both concepts pretend to exploit the unique features of Dome C: superb seeing, low temperature, improved IR transmission and reduced sky background. Two preliminary concepts are presented here. The NIR instrument would cover the wavelength range 0.97 5.0 ?m and would be optimized for the K, L and M bands. The MIR instrument would observe in the range 7 30 ?m and would be specifically designed to exploit the extended portion of the Q window (20+ ?m).

Mora, A.; Eiroa, C.; Barrado Y Navascués, D.; Persi, P.; Abia, C.

320

Current status of the Hobby-Eberly Telescope wide field upgrade  

NASA Astrophysics Data System (ADS)

The Hobby-Eberly Telescope (HET) is an innovative large telescope of 9.2 meter aperture, located in West Texas at the McDonald Observatory (MDO). The HET operates with a fixed segmented primary and has a tracker which moves the four-mirror corrector and prime focus instrument package to track the sidereal and non-sidereal motions of objects. A major upgrade of the HET is in progress that will increase the pupil size to 10 meters and the field of view to 22' by replacing the corrector, tracker and prime focus instrument package. In addition to supporting the existing suite of instruments, this wide field upgrade will feed a revolutionary new integral field spectrograph called VIRUS, in support of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX?). This paper discusses the current status of this upgrade.

Hill, Gary J.; Booth, John A.; Cornell, Mark E.; Good, John M.; Gebhardt, Karl; Kriel, Herman J.; Lee, Hanshin; Leck, Ron; Moreira, Walter; MacQueen, Phillip J.; Perry, Dave M.; Rafal, Marc D.; Rafferty, Tom H.; Ramiller, Chuck; Savage, Richard D.; Taylor, Charles A.; Vattiat, Brian L.; Ramsey, Lawrence W.; Beno, Joseph H.; Beets, Timothy A.; Esguerra, Jorge D.; Häuser, Marco; Hayes, Richard J.; Heisler, James T.; Soukup, Ian M.; Zierer, Joseph J.; Worthington, Michael S.; Mollison, Nicholas T.; Wardell, Douglas R.; Wedeking, Gregory A.

2012-09-01

321

Current status of the Hobby-Eberly Telescope wide field upgrade and VIRUS  

NASA Astrophysics Data System (ADS)

The Hobby-Eberly Telescope (HET) is an innovative large telescope of 9.2 meter aperture, located in West Texas at the McDonald Observatory. The HET operates with a fixed segmented primary and has a tracker which moves the fourmirror corrector and prime focus instrument package to track the sidereal and non-sidereal motions of objects. A major upgrade of the HET is in progress that will substantially increase the field of view by replacing the corrector, tracker and prime focus instrument package. In addition to supporting the existing suite of instruments, this wide field upgrade will feed a revolutionary new integral field spectrograph called VIRUS, in support of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). This paper discusses the current status of this upgrade.

Savage, Richard D.; Booth, John A.; Gebhardt, Karl; Good, John M.; Hill, Gary J.; MacQueen, Phillip J.; Rafal, Marc D.; Smith, Michael P.; Vattiat, Brian L.

2008-08-01

322

Current status of the Hobby-Eberly Telescope wide-field upgrade  

NASA Astrophysics Data System (ADS)

The Hobby-Eberly Telescope (HET) is an innovative large telescope of 9.2 meter aperture, located in West Texas at the McDonald Observatory (MDO). The HET operates with a fixed segmented primary and has a tracker which moves the four-mirror corrector and prime focus instrument package to track the sidereal and non-sidereal motions of objects. A major upgrade of the HET is in progress that will increase the pupil size to 10 meters and the field of view to 22' by replacing the corrector, tracker and prime focus instrument package. In addition to supporting the existing suite of instruments, this wide field upgrade will feed a revolutionary new integral field spectrograph called VIRUS, in support of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX?). This paper discusses the current status of this upgrade.

Savage, Richard; Booth, John; Cornell, Mark; Good, John; Hill, Gary J.; Lee, Hanshin; MacQueen, Phillip; Rafal, Marc; Vattiat, Brian; Gebhardt, Karl; Beno, Joseph; Zierer, Joseph; Perry, Dave; Rafferty, Tom; Ramiller, Chuck; Taylor, Charles, III; Beets, Timothy; Hayes, Richard; Heisler, James; Hinze, Sarah; Soukup, Ian; Jackson, John; Mock, Jason; Worthington, Michael; Mollison, Nicholas; Molina, Omar; South, Brian; Wardell, Douglas; Wedeking, Gregory

2010-07-01

323

An in-depth assessment of internal contamination in the Wide Field/Planetary Camera  

NASA Technical Reports Server (NTRS)

Following thermal vacuum/thermal balance testing, a gray haze was discovered on the corners of the Hubble Space Telescope Wide-Field/Planetary Camera aperture window. The phenomenon was suggested to be a result of molecular transport from a low-outgassig structural adhesive. Detailed analysis, both chemical and analytical, were conducted to assess the formation of the haze. Each material was considered individually, as it was not known if the actual contamination was a result of one, many, or possibly none of the materials considered. Results of the analytical assessment and the comparison with the chemical analyses provided incontrovertible evidence as to the cause of the window haze. The resultant cleanup and subsequent elimination of the problem are also addressed.

Maag, Carl; Millard, Jerry; Anderson, Mark

1990-01-01

324

Design and performance analysis of the wide-field infrared explorer H2/H2 cryostat  

NASA Astrophysics Data System (ADS)

The wide-field infrared explorer (WIRE) is a small explorer (SMEX) mission that will fly in the fall of 1998. The WIRE mission proposes to conduct a 4-month survey of more than 100 degree2 of sky using 12- and 25-micrometers detectors. The instrument requires cryogenic cooling of its focal planes and telescope in order to achieve the required performance sensitivity. In addition, because of the SMEX nature of the experiment, the mass of the cryostat must be less than 60 kg. The most mass efficient system meeting the lifetime requirement was determined to be a dual stage H2/H2 cryostat. The focal planes are conductively cooled by the primary H2 while the telescope is cooled by the secondary H2. The secondary H2 also protects the primary H2 by intercepting the parasitic heat loads. This paper describes the design and performance of the H2/H2 cryostat.

Costanzo, Brenda J.; Menteur, P. A.; Schick, Scott; Foster, W. G.

1996-10-01

325

A Novel Technique for Wide-Field Polarimetry with a Radio Telescope Array  

NASA Astrophysics Data System (ADS)

We report the use of the Australia Telescope Compact Array (ATCA) to conduct polarimetric observations of the sky at 5 GHz. The ATCA is normally operated as an interferometer array, but these observations were conducted in a split-array mode in which the antenna elements were used as single dishes with their beams staggered to simultaneously cover a wide area of sky with a resolution of 10'. The linearly polarized sky radiation was fully characterized from measurements, made over a range of parallactic angles, of the cross-correlated signals from the orthogonal linear feeds. We describe the technique and present a polarimetric image of the Vela supernova remnant made as a test of the method. The development of the technique was motivated by the need for wide-field imaging of the foreground contamination of the polarized component of the cosmic microwave background signal.

McConnell, D.; Carretti, E.; Subrahmanyan, R.

2006-01-01

326

Wide-Field TV Observation of the Leonid Meteor Storm in 2001: Main Peak over Japan  

NASA Astrophysics Data System (ADS)

We carried out a wide-field TV observation of the strong activity of the Leonid meteor shower from 17h17m UT through 20h20m UT on 2001 November18. We detected 869 Leonid meteors, along with 32 non-Leonids. A broad peak of the activity was recognized at around 18h25mUT, when the peak influx rate of meteoroids was 1.4 × 10-5 km-2s-1 (mag <= +3). The activity of this main peak was comparable to that of a storm observed in 1999 over Europe. The activity of this peak was rich in bright meteors, including fireball class. The magnitude distribution index was 1.5 +/- 0.3 (-3 <= mag <= +1). The relationship between the observed peak and several theoretical predictions is discussed. We also discuss an ``outburst'', which consisted of at least 15 faint meteors which appeared within four seconds at 17h56m22s.

Watanabe, Jun-Ichi; Sekiguchi, Tomohiko; Shikura, Masato; Naito, Seiichiro; Abe, Shinsuke

2002-04-01

327

Near infrared FRET using wide-field fluorescence lifetime imaging in live animals  

NASA Astrophysics Data System (ADS)

One of the challenges in anti-cancer drug delivery systems is to quantitatively discriminate non-specific receptorindependent tumor accumulation from receptor-mediated uptake into the tumor cells. To overcome this challenge, we develop a new near infrared fluorescence resonance energy transfer fluorescence lifetime imaging (NIR FRET FLIM) technique with wide-field illumination strategies to validate and characterize cellular uptake in both cancer cells and normal cells with different donor-acceptor ratios in vitro and in vivo. Our results demonstrate that NIR FRET FLIM can quantitatively distinguish receptor-bound from unbound donor in live animals with high sensitivity and high accuracy. Thus, it has a great potential for the quantitative detection of targeted delivery systems for diagnostic and therapeutic use.

Zhao, Lingling; Abe, Ken; Barroso, Margarida; Intes, Xavier

2013-06-01

328

Low coherence full field interference microscopy or optical coherence tomography: recent advances, limitations and future trends  

NASA Astrophysics Data System (ADS)

Although low coherence microscopy (LCM) has been known for long time in the context of interference microscopy, coherence radar and white light interferometry, the whole subject has attracted a wide interest in the last two decades particularly accelerated by the entrance of OCT, as a noninvasive powerful technique for biomedical imaging. Today LCM can be classified into two types, both acts as three-dimensional imaging tool. The first is low temporal coherence microscopy; also known as optical coherence tomography (OCT), which is being used for medical diagnostics. The second is full field OCT in various modes and applied to various applications. FF-OCT uses low spatial and temporal coherence similar to the well-known coherence probe microscope (CPM) that have been in use for long time in optical metrology. The CPM has many advantages over conventional microscopy in its ability to discriminate between different transparent layers in a scattering medium thus allowing for precise noninvasive optical probing of dense tissue and other turbid media. In this paper the status of this technology in optical metrology applications will be discussed, on which we have been working to improve its performance, as well as its limitations and future prospective.

Abdulhalim, I.

2013-04-01

329

A wide-field near-infrared H2 2.122 ?m line survey of the Braid Nebula star formation region in Cygnus OB7  

NASA Astrophysics Data System (ADS)

Context. Outflows and jets are the first signposts of ongoing star formation processes in any molecular cloud, yet their study in optical bands provides limited results due to the large extinction present. Near-infrared unbiased wide-field observations in the H2 1-0 S(1) line at 2.122 ?m alleviates the problem, enabling us to detect more outflows and trace them closer to their driving sources. Aims: As part of a large-scale multi-waveband study of ongoing star formation in the Braid Nebula star formation region, we focus on a one square degree region that includes Lynds Dark Nebula 1003 and 1004. Our goal is to find all of the near-infrared outflows, uncover their driving sources and estimate their evolutionary phase. Methods: We use near-infrared wide-field observations obtained with WFCAM on UKIRT, in conjunction with previously-published optical and archival MM data, to search for outflows and identify their driving sources; we subsequently use colour - colour analysis to determine the evolutionary phase of each source. Results: Within a one square degree field we have identified 37 complex MHOs, most of which are new. After combining our findings with other wide-field, multi-waveband observations of the same region we were able to discern 28 outflows and at least 18 protostars. Our analysis suggests that these protostars are younger and/or more energetic than those of the Taurus-Auriga region. The outflow data enable us to suggest connection between outflow ejection and repetitive FU Ori outburst events. We also find that star formation progresses from W to E across the investigated region. Appendices are available in electronic form at http://www.aanda.org

Khanzadyan, T.; Davis, C. J.; Aspin, C.; Froebrich, D.; Smith, M. D.; Magakian, T. Yu.; Movsessian, T.; Moriarty-Schieven, G. H.; Nikogossian, E. H.; Pyo, T.-S.; Beck, T. L.

2012-06-01

330

NASA's Challenges in Optics for Future Space-Based Science Missions  

NASA Technical Reports Server (NTRS)

NASA's mission is: "To understand and project our home planet, To explore the universe and search for life, To inspire the next generation of explorers ... as only NASA can." These mission concepts are further defined in our recently published"Strategic Objectives for 2005 and Beyond" , which include conducting advanced telescope searches for Earth-like planets and habitable environments around the stars, as well as exploring the universe to understand its origin, structure, evolution, and destiny. This presentation will summarize several future space-based missions currently in formulation to meet these objectives, and will outline some of the principal challenges in the field of optics to their success.

Stahl, H. Phil

2005-01-01

331

Design of an Off-Axis Wide Field-of-View Visual Display System for Flight Simulators.  

National Technical Information Service (NTIS)

This report describes the analysis and design of an off-axis wide field-of-view visual display system, including component specifications and structural drawings. A fabrication cost and schedule estimate is also presented. (Author)

G. T. Thomas R. L. Jones

1979-01-01

332

Near IR Fabry-Perot Interferometer for Wide Field, Low Resolution Hyperspectral Imaging on the Next Generation Space Telescope.  

National Technical Information Service (NTIS)

We discuss work in progress on a near-infrared tunable bandpass filter for the Goddard baseline wide field camera concept of the Next Generation Space Telescope (NGST) Integrated Science Instrument Module (ISIM). This filter, the Demonstration Unit for Lo...

R. K. Barry S. Satyapal M. A. Greenhouse R. Barclay D. Amato B. Arritt G. Brown V. Harvey C. Holt J. Kuhn

2000-01-01

333

Prenatal determinants of optic nerve hypoplasia: review of suggested correlates and future focus.  

PubMed

Optic nerve hypoplasia (ONH), a congenital malformation characterized by an underdeveloped optic nerve, is a seemingly epidemic cause of childhood blindness and visual impairment with associated lifelong morbidity. Although the prenatal determinants of ONH are unknown, early case reports have led to a longstanding speculation that risky health behaviors (e.g., prenatal use of recreational drugs, alcohol) are a likely culprit. There has yet to be a systematic review of the epidemiology of ONH to assess the common prenatal features that may help focus research efforts in the identification of likely prenatal correlates. A review of the past 50 years of epidemiologic research was conducted to examine the prenatal features linked with ONH and provide direction for future research. There are select prominent prenatal features associated with ONH: young maternal age and primiparity. Commonly implicated prenatal exposures (recreational or pharmaceutical drugs, viral infection, etc.) were rare or uncommon in large cohort studies of ONH and therefore unlikely to be major contributors to ONH. Familial cases and gene mutations are rare. The preponderance of young mothers and primiparity among cases of ONH is striking, although the significance is unclear. Recent research suggests a potential role for prenatal nutrition, weight gain, and factors of deprivation. With the rapidly increasing prevalence of ONH, future research should focus on investigating the relevance of young maternal age and primiparity and exploring the recently suggested etiologic correlates in epidemic clusters of ONH. PMID:24160732

Garcia-Filion, Pamela; Borchert, Mark

2013-01-01

334

Photometric redshifts for the CFHTLS T0004 deep and wide fields  

NASA Astrophysics Data System (ADS)

Aims: We compute photometric redshifts in the fourth public release of the Canada-France-Hawaii Telescope Legacy Survey. This unique multi-colour catalogue comprises u^*, g', r', i', z' photometry in four deep fields of 1 deg2 each and 35 deg2 distributed over three wide fields. Methods: We used a template-fitting method to compute photometric redshifts calibrated with a large catalogue of 16 983 high-quality spectroscopic redshifts from the VVDS-F02, VVDS-F22, DEEP2, and the zCOSMOS surveys. The method includes correction of systematic offsets, template adaptation, and the use of priors. We also separated stars from galaxies using both size and colour information. Results: Comparing with galaxy spectroscopic redshifts, we find a photometric redshift dispersion, ?? z/(1+z_s), of 0.028-0.30 and an outlier rate, |? z| ? 0.15× (1+z_s), of 3-4% in the deep field at i'_AB < 24. In the wide fields, we find a dispersion of 0.037-0.039 and an outlier rate of 3-4% at i'_AB < 22.5. Beyond i'_AB = 22.5 in the wide fields the number of outliers rises from 5% to 10% at i'_AB < 23 and i'_AB < 24, respectively. For the wide sample the systematic redshift bias stays below 1% to i'_AB < 22.5, whereas we find no significant bias in the deep fields. We investigated the effect of tile-to-tile photometric variations and demonstrated that the accuracy of our photometric redshifts is reduced by at most 21%. Application of our star-galaxy classifier reduced the contamination by stars in our catalogues from 60% to 8% at i'_AB < 22.5 in our field with the highest stellar density while keeping a complete galaxy sample. Our CFHTLS T0004 photometric redshifts are distributed to the community. Our release includes 592891 (i'_AB < 22.5) and 244701 (i'_AB < 24) reliable galaxy photometric redshifts in the wide and deep fields, respectively. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii. This work is based in part on data products produced at Terapix and the Canadian Astronomy Data Centre as part of the Canada-France-Hawaii Telescope Legacy Survey, a collaborative project of NRC and CNRS.

Coupon, J.; Ilbert, O.; Kilbinger, M.; McCracken, H. J.; Mellier, Y.; Arnouts, S.; Bertin, E.; Hudelot, P.; Schultheis, M.; Le Fèvre, O.; Le Brun, V.; Guzzo, L.; Bardelli, S.; Zucca, E.; Bolzonella, M.; Garilli, B.; Zamorani, G.; Zanichelli, A.; Tresse, L.; Aussel, H.

2009-06-01

335

Futurity  

NSDL National Science Digital Library

The Futurity website features "the latest discoveries by scientists at top research universities in the US, UK, Canada and Australia." Currently, some of the participating universities include Boston University, Duke University, McGill University, and the University of Sheffield. Visitors to the homepage will note that there are four areas on the site: Earth & Environment, Health & Medicine, Science & Technology, and Society & Culture. Recently profiled news items include a compelling new discovery from New York University about the reality of a tractor beam that can pull microscopic particles. The Society & Culture section is a real find, as it contains engaging pieces like "Is zero tolerance too hard on students?" and "Big banks loom over finance 'ecosystem'." Also, visitors can browse news items by school or by topic area. Finally, the Week's Most Discussed area is a great way to learn about compelling new stories from around the globe.

336

Space Active Optics: toward optimized correcting mirrors for future large spaceborne observatories  

NASA Astrophysics Data System (ADS)

Wave-front correction in optical instruments is often needed, either to compensate Optical Path Differences, off-axis aberrations or mirrors deformations. Active optics techniques are developed to allow efficient corrections with deformable mirrors. In this paper, we will present the conception of particular deformation systems which could be used in space telescopes and instruments in order to improve their performances while allowing relaxing specifications on the global system stability. A first section will be dedicated to the design and performance analysis of an active mirror specifically designed to compensate for aberrations that might appear in future 3m-class space telescopes, due to lightweight primary mirrors, thermal variations or weightless conditions. A second section will be dedicated to a brand new design of active mirror, able to compensate for given combinations of aberrations with a single actuator. If the aberrations to be corrected in an instrument and their evolutions are known in advance, an optimal system geometry can be determined thanks to the elasticity theory and Finite Element Analysis.

Laslandes, Marie; Hugot, Emmanuel; Ferrari, Marc; Lemaitre, Gérard; Liotard, Arnaud

2011-09-01

337

Thermal Vacuum Test Performance of the Hubble Space Telescope (HST) Wide Field Camera 3 (WFC3) Variable Conductance Heat Pipe Assembly  

NASA Technical Reports Server (NTRS)

The Variable Conductance Heat Pipe (VCHP) Assembly of the HST Wide Field Camera 3 was subjected to thermal vacuum (TN) environmental testing. The test program included both maximum and minimum environments as well as simulated on-orbit cycling. Elements of the VCHP assembly included a VCHP, an optical bench cold plate with an imbedded constant conductance heat pipe, and a VCHP reservoir radiator with a proportionally controlled heater. The purpose of the test was to characterize and demonstrate the assembly s ability to control the temperature of the cold plate, which provides a stable thermal environment for the instrument s optical bench. This paper discusses the VCHP Assembly control performance and control authority during the dynamic hot and cold 90-minute orbit cycling test phases.

Cleveland, Paul E.; Buchko, Matthew T.; Stavely, Richard A.

2003-01-01

338

A deep, wide-field study of Holmberg II with Suprime-Cam: evidence for ram pressure stripping  

NASA Astrophysics Data System (ADS)

We present a deep, wide-field optical study of the M81 group dwarf galaxy Holmberg II (HoII) based on Subaru/Suprime-Cam imaging. Individual stars are resolved down to I ˜ 25.2, that is, about 1.5 mag below the tip of the red giant branch (RGB). We use resolved star counts in the outskirts of the galaxy to measure the radial surface brightness profile down to ?V ˜ 32 mag arcsec-2, from which we determine a projected exponential scalelength of 0.70 ± 0.01 arcmin (i.e. 0.69 ± 0.01 kpc). The composite profile, ranging from the cored centre out to R = 7 arcmin, is best fitted by an Elson-Fall-Freeman profile which gives a half-light radius of 1.41 ± 0.04 arcmin (i.e. 1.39 ± 0.04 kpc), and an absolute magnitude MV = -16.3. The low surface brightness stellar component of HoII is regular and symmetric and has an extent much smaller than the vast H I cloud in which it is embedded. We compare the spatial distribution of the young, intermediate-age and old stellar populations, and find that the old RGB stars are significantly more centrally concentrated than the young stellar populations, contrary to what is observed in most dwarf galaxies of the local Universe. We discuss these properties in the context of the comet-like distribution of H I gas around HoII, and argue for the presence of a hot intragroup medium in the vicinity of HoII to explain the contrasting morphologies of gas and stars. Based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Bernard, Edouard J.; Ferguson, Annette M. N.; Barker, Michael K.; Irwin, Michael J.; Jablonka, Pascale; Arimoto, Nobuo

2012-11-01

339

Tomographic phase diversity for phase retrieval on wide-field AO systems  

NASA Astrophysics Data System (ADS)

Phase diversity is a commonly used technique to retrieve the wavefront at the focal plane. The usual algorithm involves two or more images of the same target with known phase changes like defocus. It has been shown to be very efficient at measuring on-axis the non-common path aberrations of classical AO systems. In this paper, we present an evolution of this algorithm towards tomographic measurements. This novel technique is dedicated to wide-field AO systems, allowing phase retrieval on multiple layers, conjugated at various altitudes. While the general grounds are very similar to classical phase diversity, the tomographic algorithm involves two or more images with known phase changes of several targets dispatched over the entire field of view. Regularization on the phase is usualy done by factorizing it on a basis of modes, traditionally Zernike polynomials. In this paper, we discuss the choice of a proper basis in the tomographic case and show that other basis such as disk harmonics are interesting alternatives in the case of real AO systems. We additionally propose two versions for this algorithm: an image-based and a Fourier-based both leading to comparable results. We finally present the results obtained on simulated data as well as on real data obtained on the Gemini MCAO system on which this algorithm has been used to estimate and compensate for non common path aberrations.

Gratadour, Damien; Rigaut, François

2011-09-01

340

Examining the Range of Cometary Dust Characteristics with the Wide-Field Infrared Survey Explorer  

NASA Astrophysics Data System (ADS)

Cometary dust provides insight into the composition of nuclei, as well as the forces behind its ejection and evolution. In this work, we will explore the characteristics of dust as seen in the near-nucleus environments around more than 100 active comets that were observed by the Wide-Field Infrared Explorer (WISE) mission. WISE conducted an all-sky survey at near- and mid-infrared wavelengths (3.4, 4.6, 12, and 22 microns) between January and December 2010. Many of the comets detected showed comae, tails, and/or trails, making this a rich dataset with which to examine the ensemble properties of cometary dust in the Solar System. Our work includes computing thermal fits for the dust, creating color temperature maps, and constraining the grain size distributions around the comets. With these results, we aim to provide context for the Rosetta mission results as well as a broad understanding of the range of cometary dust traits within the Solar System.

Stevenson, R.; Bauer, J. M.; Kramer, E.; Mainzer, A.; Masiero, J.; Grav, T.; Fernandez, Y. R.; Lisse, C. M.; Meech, K. J.; Weissman, P. R.; Tholen, D.; Walker, R.; Wright, E. L.

2012-12-01

341

Exoplanets from the Arctic: The First Wide-field Survey at 80°N  

NASA Astrophysics Data System (ADS)

Located within 10° of the North Pole, northern Ellesmere Island offers continuous darkness in the winter months. This capability can greatly enhance the detection efficiency of planetary transit surveys and other time domain astronomy programs. We deployed two wide-field cameras at 80°N, near Eureka, Nunavut, for a 152 hr observing campaign in 2012 February. The 16 megapixel camera systems were based on commercial f/1.2 lenses with 70 mm and 42 mm apertures, and they continuously imaged 504 and 1295 deg2, respectively. In total, the cameras took over 44,000 images and produced better than 1% precision light curves for approximately 10,000 stars. We describe a new high-speed astrometric and photometric data reduction pipeline designed for the systems, test several methods for the precision flat fielding of images from very-wide-angle cameras, and evaluate the cameras' image qualities. We achieved a scintillation-limited photometric precision of 1%-2% in each 10 s exposure. Binning the short exposures into 10 minute chunks provided a photometric stability of 2-3 mmag, sufficient for the detection of transiting exoplanets around the bright stars targeted by our survey. We estimate that the cameras, when operated over the full Arctic winter, will be capable of discovering several transiting exoplanets around bright (mV < 9.5) stars.

Law, Nicholas M.; Carlberg, Raymond; Salbi, Pegah; Ngan, Wai-Hin Wayne; Ahmadi, Aida; Steinbring, Eric; Murowinski, Richard; Sivanandam, Suresh; Kerzendorf, Wolfgang

2013-03-01

342

Direction-Dependent Polarized Primary Beams in Wide-Field Synthesis Imaging  

NASA Astrophysics Data System (ADS)

The process of wide-field synthesis imaging is explored, with the aim of understanding the implications of variable, polarised primary beams for forthcoming Epoch of Reionization experiments. These experiments seek to detect weak signatures from redshifted 21 cm emission in deep residual datasets, after suppression and subtraction of foreground emission. Many subtraction algorithms benefit from low side-lobes and polarization leakage at the outset, and both of these are intimately linked to how the polarized primary beams are handled. Building on previous contributions from a number of authors, in which direction-dependent corrections are incorporated into visibility gridding kernels, we consider the special characteristics of arrays of fixed dipole antennas operating around 100-200 MHz, looking towards instruments such as the Square Kilometre Array (SKA) and the Hydrogen Epoch of Reionization Arrays (HERA). We show that integrating snapshots in the image domain can help to produce compact gridding kernels, and also reduce the need to make complicated polarized leakage corrections during gridding. We also investigate an alternative form for the gridding kernel that can suppress variations in the direction-dependent weighting of gridded visibilities by 10 s of dB, while maintaining compact support.

Mitchell, D. A.; Wayth, R. B.; Bernardi, G.; Greenhill, L. J.; Ord, S. M.

2012-12-01

343

Evidence for a far-ultraviolet spacecraft glow in the ROSAT Wide-Field Camera  

NASA Astrophysics Data System (ADS)

During a 6 month all-sky survey and subsequent operations, the ROSAT Wide-Field Camera (WFC) was subject to a dominant and unexpected source of background. The contributions of the expected components are well understood, and once these are removed the residual background shows a strong correlation with the ram angle, suggesting that it may be due to a spacecraft glow phenomenon similar to that seen in other missions, most notably the Atmospheric Explorer (AE-C) and the Space Shuttle. The microchannel plate detector used in the WFC is very insensitive to photons of energy E equal to or less than 6 eV (lambda equal to or greater than 2000 A), which implies that the spacecraft glow, if it is the cause of the excess background, may lie in the ultraviolet or far-ultraviolet bands, outside the wavelength range of the majority of the previous observations. We present the results of a computer model which show that in some orientations the sensitive surfaces are `shadowed' from the ramming gases by the bulk of the spacecraft, and that in these orientations the observed background is much reduced.

West, R. G.; Sims, M. R.; Willingale, R.

1994-01-01

344

The Wide-Field Infrared Survey Explorer (WISE): Mission Description and Initial On-Orbit Performance  

NASA Technical Reports Server (NTRS)

The all sky surveys done by the Palomar Observatory Schmidt, the European Southern Observatory Schmidt, and the United Kingdom Schmidt, the InfraRed Astronomical Satellite and the 2 Micron All Sky Survey have proven to be extremely useful tools for astronomy with value that lasts for decades. The Wide-field Infrared Survey Explorer is mapping the whole sky following its launch on 14 December 2009. WISE began surveying the sky on 14 Jan 2010 and completed its first full coverage of the sky on July 17. The survey will continue to cover the sky a second time until the cryogen is exhausted (anticipated in November 2010). WISE is achieving 5 sigma point source sensitivities better than 0.08, 0.11, 1 and 6 mJy in unconfused regions on the ecliptic in bands centered at wavelengths of 3.4, 4.6, 12 and 22 micrometers. Sensitivity improves toward the ecliptic poles due to denser coverage and lower zodiacal background. The angular resolution is 6.1", 6.4", 6.5" and 12.0" at 3.4, 4.6, 12 and 22 micrometers, and the astrometric precision for high SNR sources is better than 0.15".

Wright, Edward L.; Eisenhardt, Peter R. M.; Mainzer, Amy; Ressler, Michael E.; Cutri, Roc M.; Jarrett, Thomas; Kirkpatrick, J. Davy; Padgett, Deborah; McMillan, Robert S.; Skrutskie,Michael; Stanford, S. A.; Cohen, Martin; Walker, Russell G.; Mather, John C.; Leisawitz, David; Gautier, Thomas N., III; McLean, Ian; Benford, Dominic; Lonsdale,Carol J.; Blain, Andrew; Mendez,Bryan; Irace, William R.; Duval, Valerie; Liu, Fengchuan; Royer, Don

2010-01-01

345

The SLUGGS Survey: wide field imaging of the globular cluster system of NGC 4278  

NASA Astrophysics Data System (ADS)

We use multipointing Hubble Space Telescope Advanced Camera for Surveys and wide field Subaru Suprime-Cam imaging to study the globular cluster system of the L* elliptical galaxy NGC 4278. We have also obtained a handful of new globular cluster spectra with the Keck Deep Imaging Multi-Object Spectrograph. We determine the globular cluster surface density profile and use it to calculate the total number of globular clusters, finding the system to be slightly more populous than average for galaxies of its luminosity. We find clear evidence for bimodality in the globular cluster colour distribution and for a colour-magnitude relation in the blue subpopulation (a `blue tilt'). We also find negative radial colour gradients in both colour subpopulations of equal strength which are similar in strength to those reported in other galaxies. The sizes of NGC 4278's globular clusters decrease with redder colours and increase with galactocentric radius. The ratio of the sizes of blue to red globular clusters is independent of galactocentric radius demonstrating that internal effects are responsible for the size difference with colour.

Usher, Christopher; Forbes, Duncan A.; Spitler, Lee R.; Brodie, Jean P.; Romanowsky, Aaron J.; Strader, Jay; Woodley, Kristin A.

2013-12-01

346

The silicon micro-strip detector plane for the LOFT/wide-field monitor  

NASA Astrophysics Data System (ADS)

The main objective of the Wide Field Monitor (WFM) on the LOFT mission is to provide unambiguous detection of the high-energy sources in a large field of view, in order to support science operations of the LOFT primary instrument, the LAD. The monitor will also provide by itself a large number of results on the timing and spectral behavior of hundreds of galactic compact objects, Active Galactic Nuclei and Gamma-Ray Bursts. The WFM is based on the coded aperture concept where a position sensitive detector records the shadow of a mask projected by the celestial sources. The proposed WFM detector plane, based on Double Sided micro-Strip Silicon Detectors (DSSD), will allow proper 2-dimensional recording of the projected shadows. Indeed the positioning of the photon interaction in the detector with equivalent fine resolution in both directions insures the best imaging capability compatible with the allocated budgets for this telescope on LOFT. We will describe here the overall configuration of this 2D-WFM and the design and characteristics of the DSSD detector plane including its imaging and spectral performances. We will also present a number of simulated results discussing the advantages that this configuration offers to LOFT. A DSSD-based WFM will in particular reduce significantly the source confusion experienced by the WFM in crowded regions of the sky like the Galactic Center and will in general increase the observatory science capability of the mission.

Goldwurm, A.; Ferrando, P.; Götz, D.; Laurent, P.; Lebrun, F.; Limousin, O.; Basa, S.; Bertoli, W.; Delagnes, Eric; Dolgorouky, Y.; Gevin, O.; Gros, A.; Gouiffes, C.; Jeanneau, F.; Lachaud, C.; Llored, M.; Olivetto, C.; Prevot, G.; Renaud, D.; Rodriguez, J.; Rossin, C.; Schanne, S.; Soldi, S.; Varniere, P.

2012-09-01

347

A TECHNIQUE FOR PRIMARY BEAM CALIBRATION OF DRIFT-SCANNING, WIDE-FIELD ANTENNA ELEMENTS  

SciTech Connect

We present a new technique for calibrating the primary beam of a wide-field, drift-scanning antenna element. Drift-scan observing is not compatible with standard beam calibration routines, and the situation is further complicated by difficult-to-parameterize beam shapes and, at low frequencies, the sparsity of accurate source spectra to use as calibrators. We overcome these challenges by building up an interrelated network of source 'crossing points'-locations where the primary beam is sampled by multiple sources. Using the single assumption that a beam has 180 Degree-Sign rotational symmetry, we can achieve significant beam coverage with only a few tens of sources. The resulting network of crossing points allows us to solve for both a beam model and source flux densities referenced to a single calibrator source, circumventing the need for a large sample of well-characterized calibrators. We illustrate the method with actual and simulated observations from the Precision Array for Probing the Epoch of Reionization.

Pober, Jonathan C.; Parsons, Aaron R. [Astronomy Department, University of California, Berkeley, CA (United States); Jacobs, Daniel C. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ (United States); Aguirre, James E.; Moore, David F. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA (United States); Bradley, Richard F.; Parashare, Chaitali R. [Department of Electrical and Computer Engineering, University of Virginia, Charlottesville, VA (United States); Carilli, Chris L. [National Radio Astronomy Observatory, Socorro, NM (United States); Gugliucci, Nicole E. [Department of Astronomy, University of Virginia, Charlottesville, VA (United States)

2012-02-15

348

Hubble Space Telescope Wide Field Camera imaging of the gravitational lens 2237 + 0305  

NASA Technical Reports Server (NTRS)

Images of the gravitational lens system 2237 + 0305, taken with the HST Wide Field Camera, are analyzed. Positions for the four quasar images, accurate to +/-0.015 arcsec, and relative magnitudes in U and R, accurate to +/-0.06 and 0.04 mag, respectively, are determined. The upper limits on the observed brightness of the fifth image are found to be less than or approximately equal to 7 percent of the brightest quasar image. The mass of the lens inside 0.9 arcsec is found to be 1.08 +/-0.02 x 10 exp 10 solar masses/h100 corresponding to a mass-to-light ratio in B of 12.3h100. This solar mass/solar luminosity estimate agrees with values obtained from stellar dynamics for other elliptical galaxies. A comparison of predictions from this mass model with the measured central velocity dispersion yields a distance-independent agreement to within 10 percent, assuming isotropic velocity dispersions.

Rix, Hans-Walter; Schneider, Donald P.; Bahcall, John N.

1992-01-01

349

Performance verification testing for HET wide-field upgrade tracker in the laboratory  

NASA Astrophysics Data System (ADS)

To enable the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX), the McDonald Observatory (MDO) and the Center for Electro-mechanics (CEM) at the University of Texas at Austin are developing a new HET tracker in support of the Wide-Field Upgrade (WFU) and the Visible Integral-Field Replicable Unit Spectrograph (VIRUS). The precision tracker is required to maintain the position of a 3,100 kg payload within ten microns of its desired position relative to the telescope's primary mirror. The hardware system to accomplish this has ten precision controlled actuators. Prior to installation on the telescope, full performance verification is required of the completed tracker in CEM's lab, without a primary mirror or the telescope's final instrument package. This requires the development of a laboratory test stand capable of supporting the completed tracker over its full range of motion, as well as means of measurement and methodology that can verify the accuracy of the tracker motion over full travel (4m diameter circle, 400 mm deep, with 9 degrees of tip and tilt) at a cost and schedule in keeping with the HET WFU requirements. Several techniques have been evaluated to complete this series of tests including: photogrammetry, laser tracker, autocollimator, and a distance measuring interferometer, with the laser tracker ultimately being identified as the most viable method. The design of the proposed system and its implementation in the lab is presented along with the test processes, predicted accuracy, and the basis for using the chosen method*.

Good, John; Hayes, Richard; Beno, Joseph; Booth, John; Cornell, Mark E.; Hill, Gary J.; Lee, Hanshin; Mock, Jason; Rafal, Marc; Savage, Richard; Soukup, Ian

2010-07-01

350

Wide Field Camera 3 Instrument Handbook for Cycle 21 v. 5.0  

NASA Astrophysics Data System (ADS)

The Wide Field Camera 3 (WFC3) is a fourth-generation imaging instrument. It was installed in the Hubble Space Telescope (HST) during Servicing Mission 4 (SM4) in May 2009. WFC3 saw first light on June 24, 2009, following the cooling of its detectors. Servicing Mission 4 Observatory Verification (SMOV) activities were completed in late August 2009, and were followed by the Cycle 17 calibration and science programs. This WFC3 Instrument Handbook has been prepared by the WFC3 team at STScI. It is the basic technical reference manual for WFC3 observers. The information in this Handbook is intended to be useful for Cycle 21 Phase I proposers, for the subsequently selected General Observers (GOs) as they prepare their Phase II specifications, and for those analyzing WFC3 data. The HST Primer and the HST Call for Proposals also contain valuable information for proposers, and the Call for Proposals is the final authority on HST policy. This edition of the WFC3 Instrument Handbook (Version 5.0) was written near the end of the execution of the Cycle 19 calibration plan. It supersedes Version 4.0, and includes results from analysis of the first three cycles of on-orbit performance.

Dressel, L.

2012-12-01

351

Luminous 3 Lyman Break Galaxies in Deep and Wide Field Surveys  

NASA Astrophysics Data System (ADS)

We present a survey of bright 3 LBGs in the the NOAO Bootes fields and SDSS deep stripe field. Our new LBT U-band survey, combined with the existing NOAO Bootes field survey, allows us to build up a sample of 15,000 photometrically-selected LBGs at 3 in the 9 square degree survey area. With the large survey area, we study UV luminosity function, stellar mass function and clustering in bright 3 LBGs. We compare our results with the results measured in other high-z LBG samples to test the cold flow accretion model and put strong constraint on the cosmic star formation efficiency and star formation history in these galaxies. Furthermore, the new Bootes wide field survey and our newly coadded imaging data in SDSS deep stripe field provide a survey area two orders of magnitude larger than any of previous deep field survey, which allow us to reveal a population of the most luminous LBGs at 3. With L> 7L* and star formation rate (SFR) ~500 M/yr, these spectroscopically-confirmed LBGs are some of the rarest and most intensive star forming systems in the early Universe. The fellow-up deep spectroscopic observations and approved Spitzer and HST observations will reveal the physical properties, place these newly discovered galaxies in the context of galaxy growth through merger and cold flow accretion at the peak era of cosmic star formation,and provide a unique laboratory for galaxy formation theory.

Bian, Fuyan; Fan, X.; Jiang, L.; McGreer, I. D.; Dey, A.; Green, R. F.; Walter, F.; Maiolino, R.; Lee, K.; Dave, R.

2013-01-01

352

WIDE-FIELD WIDE-BAND INTERFEROMETRIC IMAGING: THE WB A-PROJECTION AND HYBRID ALGORITHMS  

SciTech Connect

Variations of the antenna primary beam (PB) pattern as a function of time, frequency, and polarization form one of the dominant direction-dependent effects at most radio frequency bands. These gains may also vary from antenna to antenna. The A-Projection algorithm, published earlier, accounts for the effects of the narrow-band antenna PB in full polarization. In this paper, we present the wide-band A-Projection algorithm (WB A-Projection) to include the effects of wide bandwidth in the A-term itself and show that the resulting algorithm simultaneously corrects for the time, frequency, and polarization dependence of the PB. We discuss the combination of the WB A-Projection and the multi-term multi-frequency synthesis (MT-MFS) algorithm for simultaneous mapping of the sky brightness distribution and the spectral index distribution across a wide field of view. We also discuss the use of the narrow-band A-Projection algorithm in hybrid imaging schemes that account for the frequency dependence of the PB in the image domain.

Bhatnagar, S.; Rau, U.; Golap, K., E-mail: sbhatnag@nrao.edu, E-mail: rurvashi@nrao.edu, E-mail: kgolap@nrao.edu [National Radio Astronomy Observatory, Socorro, NM 87801 (United States)

2013-06-20

353

Deconvolution of Wide-Field-of-View Measurements of Reflected Solar Radiation.  

NASA Astrophysics Data System (ADS)

Wide-field-of-view (WFOV) radiometers have been flown as part of the Earth Radiation Budget instrument on the Nimbus 6 and 7 spacecraft and as part of the Earth Radiation Budget Experiment (ERBE) instruments aboard the ERBE spacecraft and also the NOAA 9 and 10 operational spacecraft. The measurement is the integral of the reflected solar flux distribution at the top of the earth-atmosphere system over the field-of-view of the radiometer. This paper develops the solution to this two-dimensional integral equation for the albedo distribution in terms of the measurements.The assumption is made that the bidirectional function is known and is invariant with longitude. The resulting axial symmetry of the integral operator permits the separation of the two-dimensional integral equation into a set of uncoupled one-dimensional integral equations for the latitudinal functions. This permits a better understanding of the problem while also considerably reducing the computer resources required for the solution. The one-dimensional integral equations are each approximated by a matrix equation. The matrices are each ill-conditioned, due to the resolution of WFOV data. The solution is expressed in terms of observable and unobservable components. In order to produce acceptable albedo fields from WFOV measurements, it is necessary to use ancillary data for these unobservable components. The limits of resolution are also indicated.

Smith, G. Louis; Rutan, David

1990-02-01

354

The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance  

NASA Astrophysics Data System (ADS)

The all sky surveys done by the Palomar Observatory Schmidt, the European Southern Observatory Schmidt, and the United Kingdom Schmidt, the InfraRed Astronomical Satellite, and the Two Micron All Sky Survey have proven to be extremely useful tools for astronomy with value that lasts for decades. The Wide-field Infrared Survey Explorer (WISE) is mapping the whole sky following its launch on 2009 December 14. WISE began surveying the sky on 2010 January 14 and completed its first full coverage of the sky on July 17. The survey will continue to cover the sky a second time until the cryogen is exhausted (anticipated in 2010 November). WISE is achieving 5? point source sensitivities better than 0.08, 0.11, 1, and 6 mJy in unconfused regions on the ecliptic in bands centered at wavelengths of 3.4, 4.6, 12, and 22 ?m. Sensitivity improves toward the ecliptic poles due to denser coverage and lower zodiacal background. The angular resolution is 6farcs1, 6farcs4, 6farcs5, and 12farcs0 at 3.4, 4.6, 12, and 22 ?m, and the astrometric precision for high signal-to-noise sources is better than 0farcs15.

Wright, Edward L.; Eisenhardt, Peter R. M.; Mainzer, Amy K.; Ressler, Michael E.; Cutri, Roc M.; Jarrett, Thomas; Kirkpatrick, J. Davy; Padgett, Deborah; McMillan, Robert S.; Skrutskie, Michael; Stanford, S. A.; Cohen, Martin; Walker, Russell G.; Mather, John C.; Leisawitz, David; Gautier, Thomas N., III; McLean, Ian; Benford, Dominic; Lonsdale, Carol J.; Blain, Andrew; Mendez, Bryan; Irace, William R.; Duval, Valerie; Liu, Fengchuan; Royer, Don; Heinrichsen, Ingolf; Howard, Joan; Shannon, Mark; Kendall, Martha; Walsh, Amy L.; Larsen, Mark; Cardon, Joel G.; Schick, Scott; Schwalm, Mark; Abid, Mohamed; Fabinsky, Beth; Naes, Larry; Tsai, Chao-Wei

2010-12-01

355

Characterization of flight detector arrays for the wide-field infrared survey explorer  

NASA Astrophysics Data System (ADS)

The Wide-field Infrared Survey Explorer is a NASA Midex mission launching in late 2009 that will survey the entire sky at 3.3, 4.7, 12, and 23 microns (PI: Ned Wright, UCLA). Its primary scientific goals are to find the nearest stars (actually most likely to be brown dwarfs) and the most luminous galaxies in the universe. WISE uses three dichroic beamsplitters to take simultaneous images in all four bands using four 1024×1024 detector arrays. The 3.3 and 4.7 micron channels use HgCdTe arrays, and the 12 and 23 micron bands employ Si:As arrays. In order to make a 1024×1024 Si:As array, a new multiplexer had to be designed and produced. The HgCdTe arrays were developed by Teledyne Imaging Systems, and the Si:As array were made by DRS. All four flight arrays have been delivered to the WISE payload contractor, Space Dynamics Laboratory. We present initial ground-based characterization results for the WISE arrays, including measurements of read noise, dark current, flat field and latent image performance, etc. These characterization data will be useful in producing the final WISE data product, an all-sky image atlas and source catalog.

Mainzer, Amy; Larsen, Mark; Stapelbroek, Maryn G.; Hogue, Henry; Garnett, James; Zandian, Majid; Mattson, Reed; Masterjohn, Stacy; Livingston, John; Lingner, Nicole; Alster, Natali; Ressler, Michael; Masci, Frank

2008-08-01

356

Ultra-wide-field autofluorescence imaging in non-traumatic rhegmatogenous retinal detachment  

PubMed Central

Purpose Rhegmatogenous retinal detachment (RRD) affects the function of the retina before and after surgical repair. We investigated ultra-wide-field autofluorescence (UAF) abnormalities in patients with acute RRD to improve our understanding of the functional changes in the retina before and after surgery. Methods In this retrospective study, we present the UAF imaging findings of 16 patients with acute, non-traumatic RRD. Imaging was obtained with the Optos 200 Tx (Optos) in 14 eyes preoperatively and in 12 eyes postoperatively. Twelve eyes had RRDs that involved the macula (group A), whereas four eyes had macula-sparing RRDs (group B). Results All patients (100%) with bullous retinal detachments demonstrated hypofluorescence over the area of retinal detachment. A hyperfluorescent leading edge (HLE) to the retinal detachment was observed preoperatively in 100% of eyes in group A and 75% of eyes in group B. Preoperative UAF through the fovea of group A eyes was normal (30%), hypofluorescent (50%) or hyperfluorescent (20%). In all patients with a HLE preoperatively, the HLE resolved by the 1-month postoperative visit. A residual line of demarcation remained in 8 of the 12 eyes (67%). In group A eyes, postoperative granular autofluorescent changes were present in four of the nine (44%) eyes, and were associated with worse preoperative (P=0.04) and postoperative (P=0.09) visual acuity. Conclusion UAF imaging reveals abnormalities in RRDs that allow excellent demarcation of the extent of the retinal detachment and assist in preoperative characterization of the detachment and postoperative counselling.

Witmer, M T; Cho, M; Favarone, G; Paul Chan, R V; D'Amico, D J; Kiss, S

2012-01-01

357

THE WIDE-FIELD INFRARED SURVEY EXPLORER (WISE): MISSION DESCRIPTION AND INITIAL ON-ORBIT PERFORMANCE  

SciTech Connect

The all sky surveys done by the Palomar Observatory Schmidt, the European Southern Observatory Schmidt, and the United Kingdom Schmidt, the InfraRed Astronomical Satellite, and the Two Micron All Sky Survey have proven to be extremely useful tools for astronomy with value that lasts for decades. The Wide-field Infrared Survey Explorer (WISE) is mapping the whole sky following its launch on 2009 December 14. WISE began surveying the sky on 2010 January 14 and completed its first full coverage of the sky on July 17. The survey will continue to cover the sky a second time until the cryogen is exhausted (anticipated in 2010 November). WISE is achieving 5{sigma} point source sensitivities better than 0.08, 0.11, 1, and 6 mJy in unconfused regions on the ecliptic in bands centered at wavelengths of 3.4, 4.6, 12, and 22 {mu}m. Sensitivity improves toward the ecliptic poles due to denser coverage and lower zodiacal background. The angular resolution is 6.''1, 6.''4, 6.''5, and 12.''0 at 3.4, 4.6, 12, and 22 {mu}m, and the astrometric precision for high signal-to-noise sources is better than 0.''15.

Wright, Edward L.; McLean, Ian [UCLA Astronomy, P.O. Box 951547, Los Angeles, CA 90095-1547 (United States); Eisenhardt, Peter R. M.; Mainzer, Amy K.; Ressler, Michael E.; Gautier, Thomas N. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Cutri, Roc M.; Jarrett, Thomas; Kirkpatrick, J. Davy; Padgett, Deborah [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); McMillan, Robert S. [University of Arizona, 1629 East University Boulevard, Tucson, AZ 85721 (United States); Skrutskie, Michael [Department of Astronomy, University of Virginia, Charlottesville, VA 22903 (United States); Stanford, S. A. [Physics Department, University of California, Davis, CA 95616 (United States); Cohen, Martin; Walker, Russell G. [Monterey Institute for Research in Astronomy, 200 8th Street, Marina, CA 93933 (United States); Mather, John C.; Leisawitz, David; Benford, Dominic [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Lonsdale, Carol J. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Blain, Andrew, E-mail: wright@astro.ucla.ed [California Institute of Technology, Pasadena, CA 91125 (United States)

2010-12-15

358

Wide Field Collimator 2 (WFC2) for GOES Imager and Sounder  

NASA Technical Reports Server (NTRS)

Two of the GOES instruments, the Imager and the Sounder, perform scans of the Earth to provide a full disc picture of the Earth. To verify the entire scan process, an image of a target that covers an 18 deg. circular field-of-view is collimated and projected into the field of regard of each instrument. The Wide Field Collimator 2 (WFC2) has many advantages over its predecessor, WFC1, including lower thermal dissipation higher fir field MTF, smaller package, and a more intuitive (faster) focusing process. The illumination source is an LED array that emits in a narrow spectral band centered at 689 nm, within the visible spectral bands of the Imager and Sounder. The illumination level can be continuously adjusted electronically. Lower thermal dissipation eliminates the need for forced convection cooling and minimizes time to reach thermal stability. The lens system has been optimized for the illumination source spectral output and athernalized to remain in focus during bulk temperature changes within the laboratory environment. The MTF of the lens is higher than that of the WFC1 at the edge of FOV. The target is focused in three orthogonal motions, controlled by an ergonomic system that saves substantial time and produces a sharper focus. Key words: Collimator, GOES, Imager, Sounder, Projector

Etemad, Shahriar; Bremer, James C.; Zukowski, Barbara J.; Pasquale, Bert A.; zukowski, Tmitri J.; Prince, Robert E.; O'Neill, Patrick A.; Ross, Robert W.

2004-01-01

359

Threat assessment of aerial target in ultra-wide field of view infrared image  

NASA Astrophysics Data System (ADS)

When the target is several miles away from the ultra-wide field of view (UWFV) infrared warning system, it will be a point target in the infrared image, so there is no the target information of distance, geometry and texture without which it is hard to assess the threat of target accurately. It is very important for the air defense command and decision making to have a correct threat assessment of the aerial target, and at present there are few reports about the aerial target threat assessment of the UWFV infrared warning system. The characteristic of the UWFV infrared image is analyzed. A laser range finder is used to measure the initial distance of each target which will be sent back to the infrared warning system. Together with the target information of initial distance, gray value, course angle and angular altitude, considering the nonlinear characteristic of aerial target threat assessment, the threat assessment method based on RBF neural network is presented for its good self-adaptive and self study ability to solve nonlinear complex problems. After simulation experiment, it is found that this method is available and effective.

Zhou, Yulong; Xing, Mingqiang; Wang, Yongzhong

2010-05-01

360

Highlights from a Wide-field Photometric Survey of the Globular Cluster Populations of Giant Galaxies  

NASA Astrophysics Data System (ADS)

I will present recent results from a wide-field imaging survey of the globular cluster populations of a sample of giant galaxies, along with selected results from several spin-off projects made possible by the survey data. We use mosaic CCD cameras on the WIYN 3.5-m and Kitt Peak 4-m telescopes to image the globular cluster populations out to their full radial extent and select point-source globular cluster candidates in three filters (BVR or gri) to minimize contamination and enable analysis of the globular cluster color distributions. The ~35 galaxies observed to date for the survey have a range of morphological types (spiral, S0, elliptical), luminosities (M_V ~ -19 to -23), and environments (field, group, cluster) and each galaxy hosts anywhere from ~50 to several thousand globular clusters. I will summarize our findings regarding the total numbers,spatial distributions, and color (metallicity) distributions of the globular cluster populations of the target galaxies. I will also highlight results from several applications of the survey data, including an investigation of the possible link between supermassive black holes and globular cluster populations and follow-up spectroscopic studies that have yielded globular cluster metallicities, kinematics, and galaxy mass profiles for a subset of the galaxies so far. This work is supported by NSF FAculty Early Career Development (CAREER) award AST-0847109.

Rhode, Katherine L.

2014-01-01

361

Wide-Field Infrared Survey Explorer Observations of the Evolution of Massive Star-Forming Regions  

NASA Technical Reports Server (NTRS)

We present the results of a mid-infrared survey of II outer Galaxy massive star-forming regions and 3 open clusters with data from the Wide-field Infrared Survey Explorer (WISE). Using a newly developed photometric scheme to identify young stellar objects and exclude extragalactic contamination, we have studied the distribution of young stars within each region. These data tend to support the hypothesis that latter generations may be triggered by the interaction of winds and radiation from the first burst of massive star formation with the molecular cloud material leftover from that earlier generation of stars. We dub this process the "fireworks hypothesis" since star formation by this mechanism would proceed rapidly and resemble a burst of fireworks. We have also analyzed small cutout WISE images of the structures around the edges of these massive star-forming regions. We observe large (1-3 pc size) pillar and trunk-like structures of diffuse emission nebulosity tracing excited polycyclic aromatic hydrocarbon molecules and small dust grains at the perimeter of the massive star-forming regions. These structures contain small clusters of emerging Class I and Class II sources, but some are forming only a single to a few new stars.

Koenig, X. P.; Leisawitz, D. T.; Benford, D. J.; Rebull, L. M.; Padgett, D. L.; Asslef, R. J.

2012-01-01

362

Wide-Field Infrared Survey Explorer Observations of the Evolution of Massive Star-Forming Regions  

NASA Technical Reports Server (NTRS)

We present the results of a mid-infrared survey of 11 outer Galaxy massive star-forming regions and 3 open clusters with data from the Wide-field Infrared Survey Explorer (WISE). Using a newly developed photometric scheme to identify young stellar objects and exclude extragalactic contamination, we have studied the distribution of young stars within each region. These data tend to support the hypothesis that latter generations may be triggered by the interaction of winds and radiation from the first burst of massive star formation with the molecular cloud material leftover from that earlier generation of stars.We dub this process the "fireworks hypothesis" since star formation by this mechanism would proceed rapidly and resemble a burst of fireworks.We have also analyzed small cutout WISE images of the structures around the edges of these massive star-forming regions. We observe large (1-3 pc size) pillar and trunk-like structures of diffuse emission nebulosity tracing excited polycyclic aromatic hydrocarbon molecules and small dust grains at the perimeter of the massive star-forming regions. These structures contain small clusters of emerging Class I and Class II sources, but some are forming only a single to a few new stars.

Koenig, X. P.; Leisawitz, D. T.; Benford, D. J.; Rebull, L. M.; Padgett, D. L.; Assef, R. J.

2011-01-01

363

Pulsed light imaging for wide-field dosimetry of photodynamic therapy in the skin  

NASA Astrophysics Data System (ADS)

Photodynamic therapy using aminoluvelinic acid (ALA) is an FDA-approved treatment for actinic keratoses, pre-cancerous skin lesions which pose a significant risk for immunocompromised individuals, such as organ transplant recipients. While PDT is generally effective, response rates vary, largely due to variations in the accumulation of the photosensitizer protoporphyrin IX (PpIX) after ALA application. The ability to quantify PpIX production before treatment could facilitate the use of additional interventions to improve outcomes. While many groups have demonstrated the ability to image PpIX in the clinic, these systems generally require darkening the room lights during imaging, which is unpopular with clinicians. We have developed a novel wide-field imaging system based on pulsed excitation and gated acquisition to image photosensitizer activity in the skin. The tissue is illuminated using four pulsed LED's to excite PpIX, and the remitted light acquired with a synchronized ICCD. This approach facilitates real-time background subtraction of ambient light, precluding the need to darken the exam room. Delivering light in short bursts also allows the use of elevated excitation intensity while remaining under the maximum permissible exposure limits, making the modality more sensitive to photosensitizer fluorescence than standard approaches. Images of tissue phantoms indicate system sensitivity down to 250nM PpIX and images of animals demonstrate detection of PpIX fluorescence in vivo under normal room light conditions.

Davis, Scott C.; Sexton, Kristian; Chapman, Michael Shane; Maytin, Edward; Hasan, Tayyaba; Pogue, Brian W.

2014-03-01

364

A Technique for Primary Beam Calibration of Drift-scanning, Wide-field Antenna Elements  

NASA Astrophysics Data System (ADS)

We present a new technique for calibrating the primary beam of a wide-field, drift-scanning antenna element. Drift-scan observing is not compatible with standard beam calibration routines, and the situation is further complicated by difficult-to-parameterize beam shapes and, at low frequencies, the sparsity of accurate source spectra to use as calibrators. We overcome these challenges by building up an interrelated network of source "crossing points"—locations where the primary beam is sampled by multiple sources. Using the single assumption that a beam has 180° rotational symmetry, we can achieve significant beam coverage with only a few tens of sources. The resulting network of crossing points allows us to solve for both a beam model and source flux densities referenced to a single calibrator source, circumventing the need for a large sample of well-characterized calibrators. We illustrate the method with actual and simulated observations from the Precision Array for Probing the Epoch of Reionization.

Pober, Jonathan C.; Parsons, Aaron R.; Jacobs, Daniel C.; Aguirre, James E.; Bradley, Richard F.; Carilli, Chris L.; Gugliucci, Nicole E.; Moore, David F.; Parashare, Chaitali R.

2012-02-01

365

Star Formation Rate Indicators in Wide-Field Infrared Survey Preliminary Release  

NASA Astrophysics Data System (ADS)

With the goal of investigating the degree at which the MIR luminosity in the Wide-field Infrared Survey Explorer (WISE) traces the SFR, we analyse 3.4, 4.6, 12 and 22 ?m data in a sample of ~140,000 star-forming galaxies or star-forming regions covering a wide range in metallicity 7.66 < 12 + log(O/H)<9.46, with redshift z < 0.4. These star-forming galaxies or star-forming regions are selected by matching the WISE Preliminary Release Catalog with the star-forming galaxy Catalog in SDSS DR8 provided by JHU/MPA1 . We study the relationship between the luminosity at 3.4, 4.6, 12 and 22 ?m from WISE and H ? luminosity in SDSS DR8. From these comparisons, we derive reference SFR indicators for use in our analysis. Linear correlations between SFR and the 3.4, 4.6, 12 and 22 ?m luminosity are found, and calibrations of SFRs based on L(3.4), L(4.6), L(12) and L(22) are proposed. The calibrations hold for galaxies with verified spectral observations. The dispersion in the relation between 3.4, 4.6, 12 and 22 ?m luminosity and SFR relates to the galaxy's properties, such as 4000 Å break and galaxy color.

Shi, Fei; Kong, Xu; Wicker, James; Chen, Yang; Gong, Zi-Qiang; Fan, Dong-Xin

2012-06-01

366

Infrared guiding with faint stars with the wide-field infrared camera at CFHT  

NASA Astrophysics Data System (ADS)

The Canada-France-Hawaii Telescope (CFHT) is commissioning a new Wide field Infrared Camera (WIRCam) that uses a mosaic of 4 HAWAII-2RG near- infrared detectors manufactured by Rockwell. At the heart of the instrument is an On-Chip Guiding System (OCGS) that exploits the unique parallel science/guide frame readout capability of the HAWAII-2RG detectors. A small sub sample of each array is continuously read at a rate of up to 50 Hz while the integration of the science image is ongoing with the full arrays (read at a maximal rate of 1.4 s per full frame). Each of these guiding windows is centered on a star to provide an error signal for the telescope guiding. An Image Stabilizer Unit (ISU) (i.e. a tip-tilt silica plate), provides the corrections. A Proportional Integral Differential (PID) closed loop controls the ISU such that telescope tracking is corrected at a rate of 5 Hz. This paper presents the technical architecture of the guiding system and performance measurements on the sky in engineering runs with WIRCam with faint stars up to magnitude 14.

Teeple, Douglas; Riopel, Martin; Baril, Marc; Barrick, Gregory; Albert, Loic; Vermeulen, Tom; Ward, Jeff

2006-07-01

367

The on-chip guiding system of the wide-field infrared camera at CFHT  

NASA Astrophysics Data System (ADS)

The Canada-France-Hawaii Telescope (CFHT) is commissioning a new Wide field Infrared Camera (WIRCam) that uses a mosaic of 4 HAWAII-2RG near-infrared detectors manufactured by Rockwell. At the heart of the instrument is an On-Chip Guiding System (OCGS) that exploits the unique parallel science/guide frame readout capability of the HAWAII-2RG detectors. A small subsample of each array is continuously read at a rate of 50 Hz while the integration of the science image is ongoing with the full arrays. Each of these guiding windows is centered on a star to provide an error signal for the telescope guiding. An Image Stabilizer Unit (ISU) (i.e. a tip-tilt silica plate), provides the corrections. A Proportional Integral Differential (PID) closed loop controls the ISU such that telescope tracking is corrected at a rate of 5 Hz. The guide window size and readout rate are adjustable but typical numbers are 8×8-16×16 boxes read at 50 or 1.5 Hz. This paper presents the technical architecture of the guiding system and performance measurements on the sky with WIRCam.

Albert, Loic; Riopel, Martin; Teeple, Douglas; Ward, Jeff; Barrick, Greg

2005-08-01

368

SuperBIT: Wide-field, Sub-arcsecond Imaging from the Super Pressure Balloon Platform  

NASA Astrophysics Data System (ADS)

The scientific potential of near-diffraction-limited imaging from mid-latitude ultra-long duration balloon payloads is well known. The combination of diffraction-limited angular resolution, extreme stability, space-like backgrounds, and long integrations enables transformative opportunities in studies ranging from the weak lensing of galaxy clusters and cosmic shear to the search for exoplanets. Collaborators at the University of Toronto have recently integrated a half-meter class telescope with a prototype subarcsecond pointing system. SuperBIT will adapt the existing system to the requirements of the mid-latitude super-pressure balloon (SPB) payload, and demonstrate its imaging capability during an ultra-long duration balloon flight that will take off from Wanaka, New Zealand, in the 2016-17 Austral summer. The demonstration instrument will provide imaging with a half-degree field of view and 0.3-arcsecond resolution in five bands between 300 and1000 nm, with sensitivities in the shape-band exceeding 24th magnitude(>5 sigma) in 300 seconds of integration. Our observing schedule will be split between a performance verification sample, a photometric and spectroscopic calibration set, a deep field, and a science catalog. The performance verification set prioritizes a sample of thirty clusters that have been previously well studied with the HST Advanced Camera for Surveys, the Chandra X-ray observatory, and for which there are Compton-Y parameter data from millimeter-wavelengths. The photometric calibration set will be selected from the COSMOS field. The science catalog will draw from a set of more than 150 Sunyaev-Zel’dovich, X-ray, and optically selected clusters spanning a wide range of cluster masses and morphologies. Aside from demonstrating the technical approach, these data will enable a systematic program to constrain the mass-observable relations over an unprecedented scale. A successful demonstration of the technical approach and the scientific potential will motivate future development of facility-class instruments on the SPB platform.

Rhodes, Jason; Fraisse, Aurélien A.; Jones, William C.; Netterfield, Calvin Barth; Massey, Richard

2014-06-01

369

Wide-field kinematic structure of early-type galaxy halos  

NASA Astrophysics Data System (ADS)

The stellar halos of nearby galaxies bare the signatures of the mass-assembly processes that have driven galaxy evolution over the last ˜10 Gyr. Finding and interpreting these relict clues in galaxies within and beyond the local group offers one of the most promising avenues for understanding how galaxies accumulate their stars over time. To tackle this problem we have performed a systematic study of the wide-field kinematic structure of nearby (D< 30 Mpc) early-type galaxies (ETGs), based on two-dimensional absorption-line stellar spectroscopy out to several effective radii (˜3 R e). The 22 galaxies presented here span a range of environments (field, group, and cluster), intrinsic luminosities (-22.4 < Mk < -25.6), and morphologies (S0-E0). The data consist of moderate resolution integrated-stellar-light spectra extracted from the individual slitlets of custom Keck/DEIMOS slitmasks. The complicating effects of strong emission line features are avoided by targeting the spectral region surrounding the near-infrared Calcium II triplet. For each spectrum, we parameterize the line-of-sight velocity distribution (LOSVD) as a truncated Gauss-Hermite series convolved with an optimally weighted combination of stellar templates. These kinematic measurements (V, sigma, h3, and h4) are combined with literature values to construct spatially resolved maps of large-scale kinematic structure. A variety of kinematic behaviors are observed beyond ~1 Re, potentially reflecting the stochastic and chaotic assembly of stellar bulges and halos in early-type galaxies. Next, we describe a global analysis (out to 5 Re) of kinematics and metallicity in the nearest S0 galaxy, NGC 3115, along with implications for its assembly history. The data include high-quality wide-field imaging and multi-slit spectra of the field stars and globular clusters (GCs). Within two effective radii, the bulge (as traced by the stars and metal-rich GCs) is flattened and rotates rapidly. At larger radii, the rotation declines dramatically, while the characteristic GC metallicities also decrease with radius. We argue that this pattern is not naturally explained by a binary major merger, but instead by a two-phase assembly process where the inner regions have formed in an early violent, dissipative phase, followed by the protracted growth of the outer parts via minor mergers. To test this hypothesis and improve our understanding of the growth of stellar halos we compare our observational results to high-resolution cosmological galaxy simulations. We describe a methodology for visualizing these data and present our initial comparisons between theory and observation, which suggest that the aggregate effects of many minor mergers dictate the large-scale kinematic structure of present day ETGs.

Arnold, Jacob Antony

370

THERMAL MODEL CALIBRATION FOR MINOR PLANETS OBSERVED WITH WIDE-FIELD INFRARED SURVEY EXPLORER/NEOWISE  

SciTech Connect

With the Wide-field Infrared Survey Explorer (WISE), we have observed over 157,000 minor planets. Included in these are a number of near-Earth objects, main-belt asteroids, and irregular satellites which have well measured physical properties (via radar studies and in situ imaging) such as diameters. We have used these objects to validate models of thermal emission and reflected sunlight using the WISE measurements, as well as the color corrections derived in Wright et al. for the four WISE bandpasses as a function of effective temperature. We have used 50 objects with diameters measured by radar or in situ imaging to characterize the systematic errors implicit in using the WISE data with a faceted spherical near-Earth asteroid thermal model (NEATM) to compute diameters and albedos. By using the previously measured diameters and H magnitudes with a spherical NEATM model, we compute the predicted fluxes (after applying the color corrections given in Wright et al.) in each of the four WISE bands and compare them to the measured magnitudes. We find minimum systematic flux errors of 5%-10%, and hence minimum relative diameter and albedo errors of {approx}10% and {approx}20%, respectively. Additionally, visible albedos for the objects are computed and compared to the albedos at 3.4 {mu}m and 4.6 {mu}m, which contain a combination of reflected sunlight and thermal emission for most minor planets observed by WISE. Finally, we derive a linear relationship between subsolar temperature and effective temperature, which allows the color corrections given in Wright et al. to be used for minor planets by computing only subsolar temperature instead of a faceted thermophysical model. The thermal models derived in this paper are not intended to supplant previous measurements made using radar or spacecraft imaging; rather, we have used them to characterize the errors that should be expected when computing diameters and albedos of minor planets observed by WISE using a spherical NEATM model.

Mainzer, A.; Masiero, J.; Bauer, J.; Ressler, M.; Eisenhardt, P. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Grav, T. [Department of Physics and Astronomy, Johns Hopkins University, 366 Bloomberg Center, 3400 N. Charles Street, Baltimore, MD 21218 (United States); Wright, E. [UCLA Astronomy, P.O. Box 91547, Los Angeles, CA 90095-1547 (United States); Cutri, R. M. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); McMillan, R. S. [Lunar and Planetary Laboratory, University of Arizona, 1629 East University Blvd., Kuiper Space Science Bldg. 92, Tucson, AZ 85721-0092 (United States); Cohen, M., E-mail: amainzer@jpl.nasa.gov [Radio Astronomy Laboratory, 601 Campbell Hall, University of California, Berkeley, CA 94720 (United States)

2011-08-01

371

A Wide-field near- and Mid-infrared Census of Young Stars in NGC 6334  

NASA Astrophysics Data System (ADS)

This paper presents a study of the rate and efficiency of star formation in the NGC 6334 star-forming region. We obtained observations at J, H, and Ks taken with the NOAO Extremely Wide-Field Infrared Imager and combined them with observations taken with the Infrared Array Camera (IRAC) on the Spitzer Space Telescope at wavelengths = 3.6, 4.5, 5.8, and 8.0 ?m. We also analyzed previous observations taken at 24 ?m using the Spitzer MIPS camera as part of the MIPSGAL survey. We have produced a point source catalog with >700, 000 entries. We have identified 2283 young stellar object (YSO) candidates, 375 Class I YSOs, and 1908 Class II YSOs using a combination of existing IRAC-based color classification schemes that we have extended and validated to the near-IR for use with warm Spitzer data. We have identified multiple new sites of ongoing star formation activity along filamentary structures extending tens of parsecs beyond the central molecular ridge of NGC 6334. By mapping the extinction, we derived an estimate for the gas mass, 2.2 × 105 M ?. The heavy concentration of protostars along the dense filamentary structures indicates that NGC 6334 may be undergoing a "mini-starburst" event with ?SFR > 8.2 M ? Myr-1 pc-2 and SFE > 0.10. We have used these estimates to place NGC 6334 in the Kennicutt-Schmidt diagram to help bridge the gap between observations of local low-mass star-forming regions and star formation in other galaxies.

Willis, S.; Marengo, M.; Allen, L.; Fazio, G. G.; Smith, H. A.; Carey, S.

2013-12-01

372

Design of a compact wide field telescope for space situational awareness  

NASA Astrophysics Data System (ADS)

The European Space Agency, in the framework of its Space Situational Awareness (SSA) Preparatory Programme, has commissioned a study for a global network of surveillance telescopes to monitor the ever increasing number of objects in Earth orbit. A possible scenario identified by the study is a network of 20 SSA Telescopes located at various observatory sites. This paper presents the conceptual design of a telescope system optimised for wide field, short exposures and fast tracking - all requirements of SSA. The requirements of the SSA telescope will be presented followed by a brief review of potential telescope technologies. Following a trade study analysis a 1 m compact Schmidt telescope design was chosen. This design provides a field of view of 3.4 degrees diameter. The design is achromatic and covers the wavelength range 380 - 900 nm. The sensitivity of the telescope is such that it can monitor the orbital parameters of objects as small as 1 cm in low Earth orbit. This is equivalent to 17th magnitude in 0.07 seconds at a signal to noise ratio of 5. The telescope is mounted on an Altitude- Azimuth type mount that enables wide coverage of the sky and fast tracking speeds. The entire telescope is contained within a Calotte type enclosure. The camera, detector control, and telescope control system design will also be presented. Systems engineering aspects will be addressed, with particular attention given to the analysis and flow-down of requirements and a practical and pragmatic process of system-level design trade-offs.

Lee, David; Born, Andrew; Parr-Burman, Philip; Hastings, Peter; Stobie, Brian; Bezawada, Naidu

2012-09-01

373

Searching for transits in the Wide Field Camera Transit Survey with difference-imaging light curves  

NASA Astrophysics Data System (ADS)

The Wide Field Camera Transit Survey is a pioneer program aiming at for searching extra-solar planets in the near-infrared. The images from the survey are processed by a data reduction pipeline, which uses aperture photometry to construct the light curves. We produce an alternative set of light curves using the difference-imaging method for the most complete field in the survey and carry out a quantitative comparison between the photometric precision achieved with both methods. The results show that difference-photometry light curves present an important improvement for stars with J > 16. We report an implementation on the box-fitting transit detection algorithm, which performs a trapezoid-fit to the folded light curve, providing more accurate results than the box-fitting model. We describe and optimize a set of selection criteria to search for transit candidates, including the V-shape parameter calculated by our detection algorithm. The optimized selection criteria are applied to the aperture photometry and difference-imaging light curves, resulting in the automatic detection of the best 200 transit candidates from a sample of ~475 000 sources. We carry out a detailed analysis in the 18 best detections and classify them as transiting planet and eclipsing binary candidates. We present one planet candidate orbiting a late G-type star. No planet candidate around M-stars has been found, confirming the null detection hypothesis and upper limits on the occurrence rate of short-period giant planets around M-dwarfs presented in a prior study. We extend the search for transiting planets to stars with J ? 18, which enables us to set a stricter upper limit of 1.1%. Furthermore, we present the detection of five faint extremely-short period eclipsing binaries and three M-dwarf/M-dwarf binary candidates. The detections demonstrate the benefits of using the difference-imaging light curves, especially when going to fainter magnitudes.

Zendejas Dominguez, J.; Koppenhoefer, J.; Saglia, R. P.; Birkby, J. L.; Hodgkin, S. T.; Kovács, G.; Pinfield, D. J.; Sip?cz, B.; Barrado, D.; Bender, R.; del Burgo, C.; Cappetta, M.; Martín, E. L.; Nefs, S. V.; Riffeser, A.; Steele, P.

2013-12-01

374

A deep and wide-field view at the IC 2944/2948 complex in Centaurus*  

NASA Astrophysics Data System (ADS)

We employed the ESO Max Planck Institute (MPI) wide-field camera (Baade et al.) and obtained deep images in the VIC pass-bands in the region of the IC 2944/2948 complex (l ˜ 294.8° b ˜ -1.6°), and complemented them with literature and archival data. We used this material to derive the photometric, spectroscopic and kinematic properties of the brightest (V < 16) stars in the region. The VI deep photometry on the other end, helped us to unravel the lower main sequence of a few, possibly physical, star groups in the area. Our analysis confirmed previous suggestions that the extinction towards this line of sight follows the normal law (RV = 3.1). We could recognize B-type stars spread in distance from a few hundred pc to at least 2 kpc. We found two young groups (age ˜ 3 Myr) located, respectively, at about 2.3 and 3.2 kpc from the Sun. They are characterized by a significant variable extinction (E(B - V) ranging from 0.28 to 0.45 mag), and host a significant pre-main-sequence population. We computed the initial mass functions for these groups and obtained slopes ? from -0.94 to -1.02 (e? = 0.3) in a scale where the classical Salpeter law is -1.35. We estimated the total mass of both main stellar groups in ˜1100 and ˜500 M?, respectively. Our kinematic analysis indicated that both groups of stars deviate from the standard rotation curve of the Milky Way, in line with literature results for this specific Galactic direction. Finally, along the same line of sight, we identified a third group of early-type stars located at ˜8 kpc from the Sun. This group might be located in the far side of the Sagittarius-Carina spiral arm.

Baume, G.; Rodríguez, M. J.; Corti, M. A.; Carraro, G.; Panei, J. A.

2014-09-01

375

Tracker controls development and control architecture for the Hobby-Eberly Telescope Wide Field Upgrade  

NASA Astrophysics Data System (ADS)

To enable the Hobby-Eberly Telescope Wide Field Upgrade, the University of Texas Center for Electromechanics and McDonald Observatory are developing a precision tracker system - a 15,000 kg robot to position a 3,100 kg payload within 10 microns of a desired dynamic track. Performance requirements to meet science needs and safety requirements that emerged from detailed Failure Modes and Effects Analysis resulted in a system of 14 precision controlled actuators and 100 additional analog and digital devices (primarily sensors and safety limit switches). This level of system complexity and emphasis on fail-safe operation is typical of large modern telescopes and numerous industrial applications. Due to this complexity, demanding accuracy requirements, and stringent safety requirements, a highly versatile and easily configurable centralized control system that easily links with modeling and simulation tools during the hardware and software design process was deemed essential. The Matlab/Simulink simulation environment, coupled with dSPACE controller hardware, was selected for controls development and realization. The dSPACE real-time operating system collects sensor information; motor commands are transmitted over a PROFIBUS network to servo amplifiers and drive motor status is received over the same network. Custom designed position feedback loops, supplemented by feed forward force commands for enhanced performance, and algorithms to accommodate self-locking gearboxes (for safety), reside in dSPACE. To interface the dSPACE controller directly to absolute Heidenhain sensors with EnDat 2.2 protocol, a custom communication board was developed. This paper covers details of software and hardware, design choices and analysis, and supporting simulations (primarily Simulink).

Mock, Jason R.; Beno, Joe; Rafferty, Tom H.; Cornell, Mark E.

2010-07-01

376

NOTE: Multileaf collimator end leaf leakage: implications for wide-field IMRT  

NASA Astrophysics Data System (ADS)

The multi-leaf collimator (MLC) of a particular linear accelerator vendor (Millennium MLC, Varian Medical Systems, Palo Alto, CA, USA) has a maximum leaf extension of 14.5 cm. To achieve intensity modulated radiotherapy (IMRT) for fields wider than 14.5 cm all closed leaf pairs are restricted to placement inside the field. Due to the rounded leaf end design of the MLC end leaf leakage will occur in the treatment field. The implementation of direct aperture optimization in the IMRT module of a radiotherapy treatment planning system (Pinnacle, Philips Radiation Oncology Systems, Milpitas, CA) has facilitated the delivery of IMRT fields wider than 14.5 cm. The end leaf leakage of the Millennium MLC has been characterized for 6 MV photons using gafchromic and radiographic film, and the accuracy of the planning system verified. The maximum leakage measured for a single field was 0.39 cGy MU-1 for a 0 mm leaf gap and 0.51 cGy MU-1 for a 0.6 mm leaf gap. For a clinical IMRT field leaf end leakage contributed an additional 2-3 Gy over the course of treatment. The planning system underestimated the magnitude of end leaf leakage by 20-40%. The ability to deliver IMRT fields wider than 14.5 cm with the Millennium MLC has improved the efficiency and flexibility of IMRT treatments; however, significant extra dose can be introduced due to end leaf leakage. Caution should be exercised when delivering wide field IMRT as it is not a complete panacea. Any significant occurrences of end leaf leakage predicted by the planning system should be independently verified prior to delivery.

Hardcastle, N.; Metcalfe, P.; Ceylan, A.; Williams, M. J.

2007-11-01

377

THE GLOBULAR CLUSTER SYSTEM IN M87: A WIDE-FIELD STUDY WITH CFHT/MEGACAM  

SciTech Connect

Canada-France-Hawaii Telescope Megacam data in (g', r', i') are used to obtain deep, wide-field photometry of the globular cluster system (GCS) around M87. A total of 6200 GCs brighter than i' = 23.0 (roughly equivalent to M{sub I} = -8.5) are included in the study, essentially containing almost the entire bright half of the total GC population in the galaxy. The classic bimodal metal-poor and metal-rich sequences of GCs show up clearly. While the spatial distribution of the GCs can be traced detectably outward to R {sub gc} {approx_equal} 100 kpc and perhaps further, the blue, metal-poor subpopulation is very much more spatially extended than the red subpopulation. Both the red and blue GC subsystems have radial metallicity gradients, where mean heavy-element abundance scales with a projected galactocentric distance as Z {approx} R {sup -0.12} (blue) and R {sup -0.17} (red). The blue sequence exhibits a strongly significant mass/metallicity relation (MMR) in which the mean metallicity gradually increases with cluster luminosity as Z {approx} L {sup 0.25+}-{sup 0.05} for the luminosity range M{sub I} {approx}< -10 and the assumption of a constant M/L. However, this relation is also clearly nonlinear: fainter than this level, the sequence is more nearly vertical. This mass/metallicity trend can be understood as the result of self-enrichment within the most massive metal-poor GCs during their formation. The red sequence formally exhibits a negatively sloped MMR, but the numerical solutions and tests show that this red-GC slope is not very significant. In giant elliptical galaxies, the red GCs are likely to represent a broad composite population formed during several major starbursts. If so, the red sequence might display a population-based MMR that could in principle be either positive or negative.

Harris, William E., E-mail: harris@physics.mcmaster.c [Department of Physics and Astronomy, McMaster University, Hamilton ON L8S 4M1 (Canada)

2009-09-20

378

Wide-field kinematic H-alpha observations of the Milky Way with a scanning and imaging Fabry-Perot - Preliminary results  

NASA Astrophysics Data System (ADS)

A new method has been developed for the large-scale kinematic study of Galactic H-alpha. A scanning Fabry-Perot interferometer is used with a wide-field optical system, and the interference rings are recorded with a photon-counting television camera. The Fabry-Perot scan is synchronized with the photon-counting acquisition. Data reduction produces a sequence of n wide-field monochromatic images, with a radial velocity spacing given by the fraction 1/n of the interferometer's free spectral range. Reduction is effected by 'photon sorting', a method which differs from that employed for Taurus by Atherton et al. (1982). This procedure has been successfully tested on the sky, in spite of a very short total integration time (10 min). Twenty-five monochromatic images of a 15 deg x 17.5 deg field in Orion have been reconstituted over a range of + or - 174 km/s with respect to the rest wavelength of H-alpha, with a step of 14.5 km/s.

Caplan, J.; Perrin, J.-M.; Sivan, J.-P.

1985-04-01

379

Experience Using the Heidelberg Retina Angiograph 2 with a Wide-Field Contact Lens System in Diabetic Retinopathy Cases  

PubMed Central

Introduction: HRA (Heiderberg Retina Angiograph) 2 uses a confocal scanning laser system which can provide high quality digital images but its imaging field is only 30°at most. HRA2 with a wide-field contact lens system allows an imaging field of up to 150°. Methods: We examined the advantages and disadvantages of HRA2, with a wide-field contact lens, for the evaluating diabetic retinopathy (DR). Results: HRA2 was beneficial for obtaining images of the entire retina simultaneously, without missing peripheral retinal non-perfusion and neovascularization. On the other hand, clear images connot be acquired in cases with media opacities such as corneal dystrophy, cataract and asteroid hyalosis, or in those with yellow tinted IOL. Conclusions: HRA2 with a wide-field contact lens is useful for visualizing peripheral retinal lesions in DR cases.

Shiibashi, Miyo; Yoshimoto, Miwako; Shigeeda, Takashi; Kitano, Shigehiko; Kato, Satoshi

2013-01-01

380

Systems, computer-implemented methods, and tangible computer-readable storage media for wide-field interferometry  

NASA Technical Reports Server (NTRS)

Disclosed herein are systems, computer-implemented methods, and tangible computer-readable storage media for wide field imaging interferometry. The method includes for each point in a two dimensional detector array over a field of view of an image: gathering a first interferogram from a first detector and a second interferogram from a second detector, modulating a path-length for a signal from an image associated with the first interferogram in the first detector, overlaying first data from the modulated first detector and second data from the second detector, and tracking the modulating at every point in a two dimensional detector array comprising the first detector and the second detector over a field of view for the image. The method then generates a wide-field data cube based on the overlaid first data and second data for each point. The method can generate an image from the wide-field data cube.

Lyon, Richard G. (Inventor); Leisawitz, David T. (Inventor); Rinehart, Stephen A. (Inventor); Memarsadeghi, Nargess (Inventor)

2012-01-01

381

Light weight optics made by glass thermal forming for future x-ray telescopes  

NASA Astrophysics Data System (ADS)

Future X-ray observatory missions, such as IXO or Gen-X, require grazing incidence optics of large collecting area in combination with a very good angular resolution. Wolter type I X-ray telescopes made of slumped glass segments could be a possible alternative to silicon pore optics. To achieve these requirements we develop slumping methods for high accuracy segments by experimental means. In particular, we follow the approach of indirect slumping and aim to produce parabola and hyperbola in one piece. In order to avoid internal stress in the glass segments the thermal expansion coefficient of the glass should closely match the thermal expansion of the mould material. Currently we focus on a combination of the alloy KOVAR for the mould and D263 for the glass; additionally a platinum-coated silica as mould material is studied. We investigate the behaviour of both materials during slumping in order to obtain the ideal environment for the slumping process. Additionally we report on the design of different metrology methods to measure the figure and thickness variations of the glass segments in visual light, e.g. interference, and on bearings used for shape measurements and integration.

Winter, Anita; Vongehr, Monika; Friedrich, Peter

2010-07-01

382

Polymer Nanocomposites for Electro-Optics: Perspectives on Processing Technologies, Material Characterization, and Future Application  

NASA Astrophysics Data System (ADS)

This review concentrates on semiconductors and carbon nanotubes as the inorganic component of organic-inorganic nanomaterials. One of the cornerstones of the current push towards future improvements in electronics and in optics technology is the decrease in size of the various components used for device manufacture. This paper discusses the character of nanocomposites for optics and electronics, their preparation, and the properties of semiconductor nanoparticles such as ZnS, ZnO, ZnS:Mn, TiO2, CdSe, and CdS. Research in this area has shown the great potential advantages of novel materials composed of semiconductor nanocrystals and a polymer matrix. A short characterization of the nature of carbon-based materials (i.e., fullerenes and nanotubes) is given to provide a brief review of these materials. Then, the characterization of non-conjugated (PMMA, PS, and PVDF) and conjugated (PT, PVK, PPV, and PANI) polymer matrices and nanocomposites is described. Finally, the most advanced applications of the nanocomposites are presented.

Matras-Postolek, Katarzyna; Bogdal, Dariusz

383

A very wide field wavefront sensor for a very narrow field interferometer  

Microsoft Academic Search

The LINC-NIRVANA wavefront sensors are in their AIT phase. The first Ground-layerWavefront Sensor (GWS) is shaping in the Adaptive Optics laboratory of the Astronomical Observatory of Padova, while both the Mid- High Wavefront Sensors (MHWSs) have been aligned and tested as stand-alone units in the Observatory of Bologna (MHWS#1 aligned to LINC-NIRVANA post focal relay optics). LINC-NIRVANA is a Fizeau

V. Viotto; R. Ragazzoni; C. Arcidiacono; M. Bergomi; A. Brunelli; M. Dima; J. Farinato; G. Gentile; D. Magrin; G. Cosentino; E. Diolaiti; I. Foppiani; M. Lombini; L. Schreiber; T. Bertram; P. Bizenberger; F. de Bonis; W. Gässler; T. Herbst; M. Kuerster; D. Meschke; L. Mohr; R.-R. Rohloff

2010-01-01

384

Color and monochrome lensless on-chip imaging of Caenorhabditis elegans over a wide field-of-view.  

PubMed

We demonstrate color and monochrome on-chip imaging of Caenorhabditis elegans samples over a wide field-of-view using incoherent lensless in-line holography. Digital reconstruction of the recorded lensless holograms rapidly creates the C. elegans images within <1 s over a field-of-view of >24 mm2. By digitally combining the reconstructed images at three different wavelengths (red, green and blue), color images of dyed samples are also acquired. This wide field-of-view and compact on-chip imaging modality also permits straightforward integration with microfluidic systems. PMID:20390127

Isikman, Serhan O; Sencan, Ikbal; Mudanyali, Onur; Bishara, Waheb; Oztoprak, Cetin; Ozcan, Aydogan

2010-05-01

385

Color and monochrome lensless on-chip imaging of Caenorhabditis elegans over a wide field-of-view  

PubMed Central

We demonstrate color and monochrome on-chip imaging of Caenorhabditis elegans samples over a wide field-of-view using incoherent lensless in-line holography. Digital reconstruction of the recorded lensless holograms rapidly creates the C. elegans images within <1 s over a field-of-view of >24 mm2. By digitally combining the reconstructed images at three different wavelengths (red, green and blue), color images of dyed samples are also acquired. This wide field-of-view and compact on-chip imaging modality also permits straightforward integration with microfluidic systems.

Isikman, Serhan O.; Sencan, Ikbal; Mudanyali, Onur; Bishara, Waheb; Oztoprak, Cetin; Ozcan, Aydogan

2010-01-01

386

Performance Comparisons Between Carbon Nanotubes, Optical, and Cu for Future High-Performance On-Chip Interconnect Applications  

Microsoft Academic Search

Optical interconnects and carbon nanotubes (CNTs) present promising options for replacing the existing Cu-based global\\/semiglobal (optics and CNT) and local (CNT) wires. We quantify the performance of these novel interconnects and compare it with Cu\\/low-kappa wires for future high-performance integrated circuits. We find that for a local wire, a CNT bundle exhibits a smaller latency than Cu for a given

Kyung-Hoae Koo; Hoyeol Cho; Pawan Kapur; Krishna C. Saraswat

2007-01-01

387

Characterizing AGB stars in Wide-field Infrared Survey Explorer (WISE) bands  

NASA Astrophysics Data System (ADS)

Aims: Since asymptotic giant branch (AGB) stars are bright and extended infrared objects, most Galactic AGB stars saturate the Wide-field Infrared Survey Explorer (WISE) detectors and therefore the WISE magnitudes that are restored by applying point-spread-function fitting need to be verified. Statistical properties of circumstellar envelopes around AGB stars are discussed on the basis of a WISE AGB catalog verified in this way. Methods: We cross-matched an AGB star sample with the WISE All-Sky Source Catalog and the Two Mircon All Sky Survey catalog. Infrared Space Observatory (ISO) spectra of a subsample of WISE AGB stars were also exploited. The dust radiation transfer code DUSTY was used to help predict the magnitudes in the W1 and W2 bands, the two WISE bands most affected by saturation, for calibration purpose, and to provide physical parameters of the AGB sample stars for analysis. Results: DUSTY is verified against the ISO spectra to be a good tool to reproduce the spectral energy distributions of these AGB stars. Systematic magnitude-dependent offsets have been identified in WISE W1 and W2 magnitudes of the saturated AGB stars, and empirical calibration formulas are obtained for them on the basis of 1877 (W1) and 1558 (W2) AGB stars that are successfully fit with DUSTY. According to the calibration formulas, the corrections for W1 at 5 mag and W2 at 4 mag are -0.383 and 0.217 mag, respectively. In total, we calibrated the W1/W2 magnitudes of 2390/2021 AGB stars. The model parameters from the DUSTY and the calibrated WISE W1 and W2 magnitudes are used to discuss the behavior of the WISE color-color diagrams of AGB stars. The model parameters also reveal that O-rich AGB stars with opaque circumstellar envelopes are much rarer than opaque C-rich AGB stars toward the anti-Galactic center direction, which we attribute to the metallicity gradient of our Galaxy. The synthetic photometry and input parameters for the model grid are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/564/A84

Lian, Jianhui; Zhu, Qingfeng; Kong, Xu; He, Jinhua

2014-04-01

388

Galaxy pairs in the Sloan Digital Sky Survey - IX. Merger-induced AGN activity as traced by the Wide-field Infrared Survey Explorer  

NASA Astrophysics Data System (ADS)

Interactions between galaxies are predicted to cause gas inflows that can potentially trigger nuclear activity. Since the inflowing material can obscure the central regions of interacting galaxies, a potential limitation of previous optical studies is that obscured active galactic nuclei (AGNs) can be missed at various stages along the merger sequence. We present the first large mid-infrared study of AGNs in mergers and galaxy pairs, in order to quantify the incidence of obscured AGNs triggered by interactions. The sample consists of galaxy pairs and post-mergers drawn from the Sloan Digital Sky Survey that are matched to detections by the Wide-Field Infrared Sky Explorer. We find that the fraction of AGNs in the pairs, relative to a mass-, redshift- and environment-matched control sample, increases as a function of decreasing projected separation. This enhancement is most dramatic in the post-merger sample, where we find a factor of 10-20 excess in the AGN fraction compared with the control. Although this trend is in qualitative agreement with results based on optical AGN selection, the mid-infrared-selected AGN excess increases much more dramatically in the post-mergers than is seen for an optical AGN. Our results suggest that energetically dominant optically obscured AGNs become more prevalent in the most advanced mergers, consistent with theoretical predictions.

Satyapal, Shobita; Ellison, Sara L.; McAlpine, William; Hickox, Ryan C.; Patton, David R.; Mendel, J. Trevor

2014-06-01

389

The Evolution of AGN and their Host Galaxies to z 1 in Wide-field Multi-wavelength Surveys  

NASA Astrophysics Data System (ADS)

Galaxy properties (i.e., luminosity, color, morphology, star-formation history) are known to evolve strongly with time. The redshift z 0.5-1.5 is believed to be a crucial epoch: (1) galaxies are evolving strongly as a function of stellar mass; (2) AGN activity is prevalent; (3) massive clusters are forming and (4) the red sequence is becoming established. To unambiguously determine the dominant physical processes which are driving the growth and evolution of galaxies and their central black holes at z 1 requires sensitive multi-wavelength wide-field surveys. We have combined the AGN identified in sensitive Chandra ACIS-I X-ray imaging ( 3200 sources; Goulding et al. 2011b), Spitzer IRAC infrared photometry ( 4800 sources), and FIRST and NVSS radio data ( 700 sources) with the Keck/DEIMOS catalog of 49,600 optical spectroscopic galaxies in the combined 3.2 deg2 DEEP2 fields. Using this extensive suite of multi-wavelength data, we have identified 2100 DEEP2 galaxies at z 0.8-1.4, which have signatures of X-ray, IR and/or radio-bright AGN. By comparing the properties of AGN in DEEP2 at z 0.8-1.4 to those of AGN in BOOTES at z 0.3-0.8 (Hickox et al. 2009), we place new direct wavelength-independent constraints on the evolution of AGN hosts. We find that whilst there is clear evidence for mass/luminosity downsizing from z 1 to the present day, there appears to be no evolution in color or morphology at this epoch, regardless of AGN accretion mode. However, from X-ray stacking analyses of IR AGN and star-forming galaxies, we find strong evidence for a large population of gas-rich (star-forming) obscured AGN which are formally undetected in the deep X-ray imaging. Taken together, this provides further indication that dust/gas rich systems may play a crucial role in galaxy evolution and the build-up of the red-sequence.

Goulding, Andy D.; DEEP2 survey Team

2012-01-01

390

New In-Flight Calibration Adjustment of the NIMBUS 6 and 7 Earth Radiation Budget Wide Field of View Radiometers  

Microsoft Academic Search

The in-flight space environment of the NIMBUS 6 and 7 earth radiation budget instrument differs in many important ways from the steady state preflight laboratory calibration environment. Because of this, the first 20 months of NIMBUS 7 wide field of view (WFOV) channels had their calibration adjusted through a comparison with the in-flight calibrated longwave scanner data. The adjustments were

H. Lee Kyle; Frederick B. House; Philip E. Ardanuy; Herbert Jacobowitz; Robert H. Maschhoff; John R. Hickey

1984-01-01

391

A New Variational Method for Erythrocyte Velocity Estimation in Wide-Field Imaging In Vivo  

Microsoft Academic Search

Measuring erythrocyte velocity in individual mi- crovessels has important applications for biomedical and func- tional imaging. Recent multiphoton fluorescence microscopy approaches require injecting fluorescent tracers; moreover, only one or few vessels can be imaged at a time. To overcome these shortcomings, we used CCD-based optical imaging of intrinsic absorption changes in macroscopic vascular networks to record erythrocytes' trajectories over several

Thomas Deneux; Olivier Faugeras; Sylvain Takerkart; Guillaume S. Masson; Ivo Vanzetta

2011-01-01

392

ProtoEXIST: balloon-borne technology development for wide-field hard X-ray imaging  

NASA Astrophysics Data System (ADS)

We report on the development of the ProtoEXIST balloon-borne experiment for development of wide-field coded aperture imaging with high spatial resolution imaging Cd-Zn-Te (CZT) arrays in close-tiled, large area configurations. ProtoEXIST1 will incorporate two coded aperture telescopes, each with 16 x 16cm close-tiled imaging CZT with 2.5mm pixels that maintain registration across the full detector. The detector plane incorporates new-technology low powered ASIC readout on each 20 x 20 x 5mm CZT crystal. A 2 x 4 array of such crystals are closetiled on a single board (DCA) with vertical integration to a controlling and readout-enabling FPGA. Detector readout modes can be commanded through the FPGA and selected in flight: from simple peak pixel, to peak plus neighbor pixels to larger pixel-selected modes, which will improve spatial/spectral resolution as well as allow for future tests of Compton imaging. The full readout consists of a 2 x 4 array of DCAs for each of the two telescopes. The detector plane is shielded from below by an active shield (2cm CsI) on one telescope vs. an equivalent graded-passive shield on the other to enable direct imaging comparisons of background rejection in a balloon environment. Both telescopes incorporate otherwise identical graded-passive side shields and laminated coded aperture masks (5mm pixels, laser-cut in W sheet). The telescopes each have 20o x 20o fields of view (FWHM), with 21arcmin resolution across the field. The ProtoEXIST gondola is derived from the old Harvard EXITE gondola but now with new pointing system and daytime star camera as developed at MSFC for the HERO balloon payload. A first flight is planned for September/October, 2008. Tests will include not only the first tests of this multipixel, controllable ASIC-readout system but also tests of the scanning coded aperture imaging as planned for the proposed EXIST mission. Followup flight(s) will test the higher-spatial resolution CZT imager (0.6mm pixels) now planned for the full EXIST mission.

Grindlay, Jonathan