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(Abridged) We describe here the most ambitious survey currently planned in the optical, the Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST will have unique survey capability in the faint time domain. The LSST design is driven by four main science themes: probing dark energy and dark matter, taking an inventory of the Solar System, exploring the transient optical sky, and mapping the Milky Way. LSST will be a wide-field ground-based system sited at Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m effective) primary mirror, a 9.6 deg$^2$ field of view, and a 3.2 Gigapixel camera. The standard observing sequence will consist of pairs of 15-second exposures in a given field, with two such visits in each pointing in a given night. With these repeats, the LSST system is capable of imaging about 10,000 square degrees of sky in a single filter in three nights. The typical 5$\sigma$ point-source depth in a single visit in $r$ will be $\sim 24.5$ (AB). The project is in the construction phase and will begin regular survey operations by 2022. The survey area will be contained within 30,000 deg$^2$ with $\delta, Comment: 57 pages, 32 color figures, version with high-resolution figures available from https://www.lsst.org/overview

Cosmology with Type Ia supernovae heretofore has required extensive spectroscopic follow-up to establish a redshift. Though tolerable at the present discovery rate, the next generation of ground-based all-sky survey instruments will render this approach unsustainable. Photometry-based redshift determination is a viable alternative, but introduces non-negligible errors that ultimately degrade the ability to discriminate between competing cosmologies. We present a strictly template-based photometric redshift estimator and compute redshift reconstruction errors in the presence of photometry and statistical errors. With reasonable assumptions for a cadence and supernovae distribution, these redshift errors are combined with systematic errors and propagated using the Fisher matrix formalism to derive lower bounds on the joint errors in $\Omega_w$ and $\Omega_w'$ relevant to the next generation of ground-based all-sky survey., Comment: 23 pages, 6 figures

We investigate the ellipticity of the point-spread function (PSF) produced by imaging an unresolved source with a telescope, subject to the effects of atmospheric turbulence. It is important to quantify these effects in order to understand the errors in shape measurements of astronomical objects, such as those used to study weak gravitational lensing of field galaxies. The PSF modeling involves either a Fourier transform of the phase information in the pupil plane or a ray-tracing approach, which has the advantage of requiring fewer computations than the Fourier transform. Using a standard method, involving the Gaussian weighted second moments of intensity, we then calculate the ellipticity of the PSF patterns. We find significant ellipticity for the instantaneous patterns (up to more than 10%). Longer exposures, which we approximate by combining multiple (N) images from uncorrelated atmospheric realizations, yield progressively lower ellipticity (as 1 / sqrt(N)). We also verify that the measured ellipticity does not depend on the sampling interval in the pupil plane using the Fourier method. However, we find that the results using the ray-tracing technique do depend on the pupil sampling interval, representing a gradual breakdown of the geometric approximation at high spatial frequencies. Therefore, ray tracing is generally not an accurate method of modeling PSF ellipticity induced by atmospheric turbulence unless some additional procedure is implemented to correctly account for the effects of high spatial frequency aberrations. The Fourier method, however, can be used directly to accurately model PSF ellipticity, which can give insights into errors in the statistics of field galaxy shapes used in studies of weak gravitational lensing., Comment: 9 pages, 5 color figures (some reduced in size). Accepted for publication in the Astrophysical Journal

Adaptive optics (AO) is a technology that corrects in real time for the blurring effects of atmospheric turbulence, in principle allowing Earth‐bound telescopes to achieve their diffraction limit and to “see” as clearly as if they were in space. The power of AO using natural guide stars has been amply demonstrated in recent years on telescopes up to 3–4 m in diameter. The next breakthrough in astronomical resolution was expected to occur with the implementation of AO on the new generation of large, 8–10 m diameter telescopes. In this paper we report the initial results from the first of these AO systems, now coming on line on the 10 m diameter Keck II Telescope. The results include the highest angular resolution images ever obtained from a single telescope (0 \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsx...

This white paper describes the LSST Dark Energy Science Collaboration (DESC), whose goal is the study of dark energy and related topics in fundamental physics with data from the Large Synoptic Survey Telescope (LSST). It provides an overview of dark energy science and describes the current and anticipated state of the field. It makes the case for the DESC by laying out a robust analytical framework for dark energy science that has been defined by its members and the comprehensive three-year work plan they have developed for implementing that framework. The analysis working groups cover five key probes of dark energy: weak lensing, large scale structure, galaxy clusters, Type Ia supernovae, and strong lensing. The computing working groups span cosmological simulations, galaxy catalogs, photon simulations and a systematic software and computational framework for LSST dark energy data analysis. The technical working groups make the connection between dark energy science and the LSST system. The working groups have close linkages, especially through the use of the photon simulations to study the impact of instrument design and survey strategy on analysis methodology and cosmological parameter estimation. The white paper describes several high priority tasks identified by each of the 16 working groups. Over the next three years these tasks will help prepare for LSST analysis, make synergistic connections with ongoing cosmological surveys and provide the dark energy community with state of the art analysis tools. Members of the community are invited to join the LSST DESC, according to the membership policies described in the white paper. Applications to sign up for associate membership may be made by submitting the Web form at http://www.slac.stanford.edu/exp/lsst/desc/signup.html with a short statement of the work they wish to pursue that is relevant to the LSST DESC.

The Large Synoptic Survey Telescope (LSST) uses a novel, three-mirror, telescope design feeding a camera system that includes a set of broad-band filters and three refractive corrector lenses to produce a flat field at the focal plane with a wide field of view. Optical design of the camera lenses and filters is integrated in with the optical design of telescope mirrors to optimize performance. We discuss the rationale for the LSST camera optics design, describe the methodology for fabricating, coating, mounting and testing the lenses and filters, and present the results of detailed analyses demonstrating that the camera optics will meet their performance goals.

Recent progress in retinal image acquisition techniques, including optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO), combined with improved performance of adaptive optics (AO) instrumentation, has resulted in improvement in the quality of in vivo images of cellular structures in the outer layers of the human retina. Despite the significant progress in imaging cone and rod photoreceptor mosaics, visualization of cellular structures in the inner retina has been achieved only with extrinsic contrast agents that have not been approved for use with humans. In this paper we describe the main limiting factors in visualizing inner retinal cells and the methods we implemented to reduce their effects on images acquired with AO-OCT. These include improving the system point spread function (AO performance), monitoring of motion artifacts (retinal motion tracking), and speckle pattern reduction (temporal and spatial averaging). Results of imaging inner retinal morphology and the improvement offered by the new UC Davis AOOCT system with spatio-temporal image averaging are presented. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Orbital debris in low Earth orbit (LEO) are now sufficiently dense that the use of LEO space is threatened by runaway collisional cascading. A problem predicted more than thirty years ago, the threat from debris larger than about 1cm demands serious attention. A promising proposed solution uses a high power pulsed laser system on the Earth to make plasma jets on the objects, slowing them slightly, and causing them to re-enter and burn up in the atmosphere. In this paper, we reassess this approach in light of recent advances in low-cost, light-weight segmented design for large mirrors, calculations of laser-induced orbit changes and in design of repetitive, multi-kilojoule lasers, that build on inertial fusion research. These advances now suggest that laser orbital debris removal (LODR) is the most costeffective way to mitigate the debris problem. No other solutions have been proposed that address the whole problem of large and small debris. A LODR system will have multiple uses beyond debris removal. International cooperation will be essential for building and operating such a system.

We propose to employ small orbit perturbations, induced by photon pressure from ground-based laser illumination, for collision avoidance in space. Possible applications would be a) protecting space assets from impacts with debris and b) stabilizing the orbital debris environment. In comparison to schemes aimed at de-orbiting debris using laser ablation, collision avoidance requires much less force and hence needs less sophisticated laser/telescope systems. In earlier research we concluded that a system consisting of a 10kW class laser, directed by a 1.5m telescope with adaptive optics, could avoid a significant fraction of collisions in low earth orbit. This paper describes our recent efforts which include refining our original analysis, employing higher fidelity simulations and presenting our planned experimental approach.

We present an evaluation of two different configurations of the ALPAO 97-actuator membrane magnetic deformable mirror for wavefront correction, using either 7 or 9 actuators across the eye pupil. These tests included monitoring of aberration correction for a human subject. This AO-sub system is part of the UC Davis high-resolution human retinal imaging adaptive optics - optical coherence tomography (AO-OCT) instrument. AO-OCT allows the three-dimensional (3D) visualization of different retinal structures in vivo with high volumetric resolution (3x3x3?m 3 ). Full Text: PDF References: [1] R.J. Zawadzki, S. Jones, S. Olivier, M. Zhao, B. Bower, J. Izatt, S. Choi, S. Laut, and J. Werner, "Adaptive-optics optical coherence tomography for high-resolution and high-speed 3D retinal in vivo imaging", Opt. Exp. 13, 8532 (2005), [CrossRef] [2] R.J. Zawadzki, B. Cense, Y. Zhang, S.S. Choi, D.T. Miller, and J.S. Werner, "Ultrahigh-resolution optical coherence tomography with monochromatic and chromatic aberration correction", Opt. Exp. 16, 8126 (2008), [CrossRef] [3] R.J. Zawadzki, S.M. Jones, S. Pilli, S. Balderas-Mata, D. Kim, S.S. Olivier, and J.S. Werner, "Integrated adaptive optics optical coherence tomography and adaptive optics scanning laser ophthalmoscope system for simultaneous cellular resolution in vivo retinal imaging", Biomed. Opt. Exp. 2, 1674 (2011), [CrossRef] [4] J. Liang, D.R. Williams and D.T. Miller, "Supernormal vision and high-resolution retinal imaging through adaptive optics", J. Opt. Soc. Am. A 14, 2884 (1997), [CrossRef] [5] A. Roorda, F. Romero-Borja, W.J. Donnelly III, H. Queener, T.J. Hebert, and M.C.W. Campbell, "Adaptive optics scanning laser ophthalmoscopy", Opt. Exp. 10, 405 (2002), [DirectLink] D. Huang, E. A. Swanson, C.P. Lin, J.S. Schuman, W.G. Stinson, W. Chang, M.R. Flotte, K. Gregory, C.A. Puliafito, "Optical coherence tomography", Science 254, 1178 (1991). [CrossRef] W. Drexler and J.G. Fujimoto, "Optical Coherence Tomography in Ophthalmology", J. Biomed. Opt. 12, 041201 (2007). [CrossRef] [8] M. Wojtkowski, "High-speed optical coherence tomography: basics and applications", Applied Optics 49, D30 (2010), [CrossRef] D.A. Horsley, H. Park, S.P. Laut and J.S. Werner, "Characterization of a bimorph deformable mirror using stroboscopic phase-shifting interferometry", Sensors and Actuators A: Physical 134, 221 (2007). [CrossRef] J.W. Evans, R.J. Zawadzki, S.M. Jones, S.S. Olivier, and J.S. Werner, "Error budget analysis for an Adaptive Optics Optical Coherence Tomography System", Opt. Exp. 17, 13768 (2009), [CrossRef] N. Doble, D.T. Miller, G. Yoon, and D.R. Williams, "Requirements for discrete actuator and segmented wavefront correctors for aberration compensation in two large populations of human eyes", Appl. Opt. 46, 4501 (2007), [CrossRef] N. Devaney, E. Dalimier, T. Farrell, D. Coburn, R. Mackey, D. Mackey, F. Laurent, E. Daly, and C. Dainty, "Correction of ocular and atmospheric wavefronts: a comparison of the performance of various deformable mirrors", Appl. Opt. 47, 6550 [CrossRef]

We describe an ultrahigh-resolution (UHR) retinal imaging system that combines adaptive optics Fourier-domain optical coherence tomography (AO-OCT) with an adaptive optics scanning laser ophthalmoscope (AO-SLO) to allow simultaneous data acquisition by the two modalities. The AO-SLO subsystem was integrated into the previously described AO-UHR OCT instrument with minimal changes to the latter. This was done in order to ensure optimal performance and image quality of the AO- UHR OCT. In this design both imaging modalities share most of the optical components including a common AO-subsystem and vertical scanner. One of the benefits of combining Fd-OCT with SLO includes automatic co-registration between two acquisition channels for direct comparison between retinal structures imaged by both modalities (e.g., photoreceptor mosaics or microvasculature maps). Because of differences in the detection scheme of the two systems, this dual imaging modality instrument can provide insight into retinal morphology and potentially function, that could not be accessed easily by a single system. In this paper we describe details of the components and parameters of the combined instrument, including incorporation of a novel membrane magnetic deformable mirror with increased stroke and actuator count used as a single wavefront corrector. We also discuss laser safety calculations for this multimodal system. Finally, retinal images acquired in vivo with this system are presented.

The Space-based Telescopes for Actionable Refinement of Ephemeris (STARE) program will collect the information needed to help satellite operators avoid collisions in space by using a network of nano-satellites to determine more accurate trajectories for selected space objects orbiting the Earth. In the first phase of the STARE program, two pathfinder cube-satellites (CubeSats) equipped with an optical imaging payload are being developed and deployed to demonstrate the main elements of the STARE concept. In this paper, we first give an overview of the STARE program. We then describe the details of the optical imaging payload for the STARE pathfinder CubeSats, including the optical design and the sensor characterization. Finally, we discuss the track detection algorithm that will be used on the images acquired by the payload.

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.

We summarize the performance of an AO-OCT system with reference arm phase shifting for complex conjugate artifactfree imaging of in vivo retinal structures. As a complex conjugate artifact removal (CCR) method we used a previously reported technique requiring constant phase shifts between consecutive A-scans. In our system these shifts were generated by continuous beam path-length changes from offsetting the pivot point of the scanning mirror placed in the system reference arm. In order to reconstruct the complex spectral fringe pattern we used Fourier transformation along the transverse axis and a filtering algorithm. The suppression ratio of mirror complex artifact images was assessed based on acquired in vivo CCR AO-OCT images. Finally, potential problems and limitations connected with this acquisition scheme and data processing algorithms are discussed.

We present a new method to directly measure and correct the aberrations introduced when imaging through thick biological tissue. A Shack-Hartmann wavefront sensor is used to directly measure the wavefront error induced by a Drosophila embryo. The wavefront measurements are taken by seeding the embryo with fluorescent microspheres used as "artificial guide-stars." The wavefront error is corrected in ten millisecond steps by applying the inverse to the wavefront error on a micro-electro-mechanical deformable mirror in the image path of the microscope. The results show that this new approach is capable of improving the Strehl ratio by 2 times on average and as high as 10 times when imaging through 100 microm of tissue. The results also show that the isoplanatic half-width is approximately 19 microm resulting in a corrected field of view 38 microm in diameter around the guide-star.

The Large Synoptic Survey Telescope (LSST) is a large aperture, wide-field facility designed to provide deep images of half the sky every few nights. There is only a single instrument on the telescope, a 9.6 square degree visible-band camera, which is mounted close to the secondary mirror, and points down toward the tertiary. The requirements of the LSST camera present substantial technical design challenges. To cover the entire 0.35 to 1 μm visible band, the camera incorporates an array of 189 over-depleted bulk silicon CCDs with 10 μm pixels. The CCDs are assembled into 3 x 3 "rafts", which are then mounted to a silicon carbide grid to achieve a total focal plane flatness of 15 μm p-v. The CCDs have 16 amplifiers per chip, enabling the entire 3.2 Gigapixel image to be read out in 2 seconds. Unlike previous astronomical cameras, a vast majority of the focal plane electronics are housed in the cryostat, which uses a mixed refrigerant Joule-Thompson system to maintain a -100oC sensor temperature. The shutter mechanism uses a 3 blade stack design and a hall-effect sensor to achieve high resolution and uniformity. There are 5 filters stored in a carousel around the cryostat and the auto changer requires a dual guide system to control its position due to severe space constraints. This paper presents an overview of the current state of the camera design and development plan.

We obtained 960,200 22-by-22-pixel windowed images of a pinhole spot using the Teledyne H2RG CMOS detector with un-cooled SIDECAR readout. We performed an analysis to determine the precision we might expect in the position error signals to a telescope's guider system. We find that, under non-optimized operating conditions, the error in the computed centroid is strongly dependent on the total counts in the point image only below a certain threshold, approximately 50,000 photo-electrons. The LSST guider camera specification currently requires a 0.04 arcsecond error at 10 Hertz. Given the performance measured here, this specification can be delivered with a single star at 14 th to 18 th magnitude, depending on the passband.

The Large Synoptic Survey Telescope (LSST) is a proposed ground based telescope that will perform a comprehensive astronomical survey by imaging the entire visible sky in a continuous series of short exposures. Four special purpose rafts, mounted at the corners of the LSST science camera, contain wavefront sensors and guide sensors. Wavefront measurements are accomplished using curvature sensing, in which the spatial intensity distribution of stars is measured at equal distances on either side of focus by CCD detectors. The four Corner Rafts also each hold two guide sensors. The guide sensors monitor the locations of bright stars to provide feedback that controls and maintains the tracking of the telescope during an exposure. The baseline sensor for the guider is a Hybrid Visible Silicon hybrid-CMOS detector. We present here a conceptual mechanical and electrical design for the LSST Corner Rafts that meets the requirements imposed by the camera structure, and the precision of both the wavefront reconstruction and the tracking. We find that a single design can accommodate two guide sensors and one split-plane wavefront sensor integrated into the four corner locations in the camera.

The Large Synoptic Survey Telescope (LSST) uses a novel, three-mirror, modified Paul-Baker design, with an 8.4-meter primary mirror, a 3.4-m secondary, and a 5.0-m tertiary feeding a refractive camera design with 3 lenses (0.69-1.55m) and a set of broadband filters/corrector lenses. Performance is excellent over a 9.6 square degree field and ultraviolet to near infrared wavelengths. We describe the image quality error budget analysis methodology which includes effects from optical and optomechanical considerations such as index inhomogeneity, fabrication and null-testing error, temperature gradients, gravity, pressure, stress, birefringence, and vibration.

Orbital collisions pose a hazard to space operations. Using a high performance computer modeling and simulation environment for space situational awareness, we explore a new paradigm for improving satellite conjunction analysis by obtaining more precise orbital information only for those objects that pose a collision risk greater than a defined threshold to a specific set of satellites during a specified time interval. In particular, we assess the improvement in the quality of the conjunction analysis that can be achieved using a distributed network of ground-based telescopes.

We describe results of retinal imaging with a novel instrument that combines adaptive optics - Fourier-domain optical coherence tomography (AO-OCT) with an adaptive optics scanning laser ophthalmoscope (AO-SLO). One of the benefits of combining Fd-OCT with SLO includes automatic co-registration between the two imaging modalities and the potential for correcting lateral and transversal eye motion resulting in motion artifact-free volumetric retinal imaging. Additionally this allows for direct comparison between retinal structures that can be imaged with both modalities (e.g., photoreceptor mosaics or microvasculature maps). This dual imaging modality could provide insight into some retinal properties that could not be accessed by a single imaging system. Additionally, extension of OCT and SLO beyond structural imaging may open new avenues for diagnostics and testing in ophthalmology. In particular, non-invasive vasculature mapping with these modalities holds promise of replacing fluorescein angiography in vascular identification. Several new improvements of our system are described, including results of testing a novel 97-actuator deformable mirror and AO-SLO light intensity modulation. © 2010 SPIE.

The combination of adaptive optics (AO) technology with optical coherence tomography (OCT) instrumentation for imaging the retina has proven to be a valuable tool for clinicians and researchers in understanding the healthy and diseased eye. The micrometer-isotropic resolution achieved by such a system allows imaging of the retina at a cellular level, however imaging of some cell types remains elusive. Improvement in contrast rather than resolution is needed and can be achieved through better AO correction of wavefront aberration. A common tool for assessing and ultimately improving AO system performance is the development of an error budget. Specifically, this is a list of the magnitude of the constituent residual errors of an optical system so that resources can be directed towards efficient performance improvement. Here we present an error budget developed for the UC Davis AO-OCT instrument indicating that bandwidth and controller errors are the limiting errors of our AO system, which should be corrected first to improve performance. We also discuss the scaling of error sources for different subjects and the need to improve the robustness of the system by addressing subject variability. © 2009 Optical Society of America.

We describe a novel instrument that combines adaptive optics - Fourier-domain optical coherence tomography (AO-OCT) with an adaptive optics scanning laser ophthalmoscope (AO-SLO). Both systems share a common AO sub-system and vertical scanner to permit simultaneous acquisition of retinal images from both OCT and SLO. One of the benefits of combining OCT with SLO includes automatic co-registration between the two imaging modalities and potential for correcting lateral and transversal eye motion resulting in motion artifact-free volumetric retinal imaging. Results of using this system for eye model imaging are presented. Feasibility for clinical application is briefly discussed as well as potential further improvements of the current system.

Adaptive optics (AO) and optical coherence tomography (OCT) are powerful imaging modalities that, when combined, can provide high-resolution (3.5 μm isotropic), 3-D images of the retina. The AO-OCT system at UC Davis has demonstrated the utility of this technology for microscopic, volumetric, in vivo retinal imaging. The current system uses an AOptix bimorph deformable mirror (DM) for low-order, high-stroke correction and a 140-actuator Boston Micromachines DM for high-order correction. Developments to improve performance or functionality of the instrument are on-going. Based on previous work in system characterization we have focused on improved AO control. We present preliminary results and remaining challenges for a newly implemented Fourier transform reconstructor (FTR). The previously reported error budget analysis is also reviewed and updated, with consideration of how to improve both the amount of residual error and the robustness of the system. Careful characterization of the AO system will lead to improved performance and inform the design of future systems.

Models are studied for the evolution of the disc of spiral galaxies that include the effects of viscosity but assume no continuous infall of gas on to the disc. The time-scale for star formation is assumed to be of the same order as the time-scale for viscous redistribution of the mass and angular momentum in the disc. It is confirmed that these models are able to reproduce the oberved radial distribution of gas and stars for present day spirals for a variety of model parameters and initial conditions

The Large Synoptic Survey Telescope (LSST) uses a novel, three-mirror, modified Paul-Baker design, with an 8.4-meter primary mirror, a 3.4-m secondary, and a 5.0-m tertiary feeding a camera system that includes a set of broad-band filters and refractive corrector lenses to produce a flat focal plane with a field of view of 9.6 square degrees. Optical design of the camera lenses and filters is integrated with optical design of telescope mirrors to optimize performance, resulting in excellent image quality over the entire field from ultra-violet to near infra-red wavelengths. The LSST camera optics design consists of three refractive lenses with clear aperture diameters of 1.55 m, 1.10 m and 0.69 m and six interchangeable, broad-band, filters with clear aperture diameters of 0.75 m. We describe the methodology for fabricating, coating, mounting and testing these lenses and filters, and we present the results of detailed tolerance analyses, demonstrating that the camera optics will perform to the specifications required to meet their performance goals.

We present extensive early photometric (ultraviolet through near-infrared) and spectroscopic (optical and near-infrared) data on supernova (SN) 2008D as well as X-ray data analysis on the associated Swift/X-ray transient (XRT) 080109. Our data span a time range of 5 hours before the detection of the X-ray transient to 150 days after its detection, and detailed analysis allowed us to derive constraints on the nature of the SN and its progenitor; throughout we draw comparisons with results presented in the literature and find several key aspects that differ. We show that the X-ray spectrum of XRT 080109 can be fit equally well by an absorbed power law or a superposition of about equal parts of both power law and blackbody. Our data first established that SN 2008D is a spectroscopically normal SN Ib (i.e., showing conspicuous He lines), and show that SN 2008D had a relatively long rise time of 18 days and a modest optical peak luminosity. The early-time light curves of the SN are dominated by a cooling stellar envelope (for \Delta t~0.1- 4 day, most pronounced in the blue bands) followed by 56^Ni decay. We construct a reliable measurement of the bolometric output for this stripped-envelope SN, and, combined with estimates of E_K and M_ej from the literature, estimate the stellar radius R_star of its probable Wolf-Rayet progenitor. According to the model of Waxman et al. and of Chevalier & Fransson, we derive R_star^{W07}= 1.2+/-0.7 R_sun and R_star^{CF08}= 12+/-7 R_sun, respectively; the latter being more in line with typical WN stars. Spectra obtained at 3 and 4 months after maximum light show double-peaked oxygen lines that we associate with departures from spherical symmetry, as has been suggested for the inner ejecta of a number of SN Ib cores., Comment: Accepted to ApJ, v3 contains more data than v2 and more references, conclusions not significantly changed, 28 pages in emulateapj, 17 figures

Adaptive optics scanning laser ophthalmoscopy allows for noninvasive, in vivo visualization of retinal abnormalities at a cellular level. We herein describe for the first time, to our knowledge, the utility of high-resolution retinal imaging in studying the photoreceptor mosaic in an otherwise unexplained visual disturbance. Imaging of the cone mosaic was performed in a 64-year-old man with a unilateral ringlike paracentral distortion that could not be explained using common clinical imaging instruments. Adaptive optics scanning laser ophthalmoscopy findings revealed a parafoveal circular abnormality of the cone mosaic approximately 3 degrees in diameter that corresponded to the ring of visual disturbance. Visualization of the cone mosaic with adaptive optics scanning laser ophthalmoscopy can reveal photoreceptor damage that may not be detectable with standard imaging devices. Optical axial sectioning of the retina may help in identifying and localizing abnormalities within the retinal layers.

Adaptive optics (AO) and optical coherence tomography (OCT) are powerful imaging modalities that, when combined, can provide high-resolution, 3-D images of the retina. The AO-OCT system at UC Davis has been under development for 2 years and has demonstrated the utility of this technology for microscopic, volumetric, in vivo retinal imaging. The current system uses a bimorph deformable mirror (DM) made by AOptix Technologies, Inc. for low-order, high-stroke correction and a 140-actuator mirco-electrical-mechanical-system (MEMS) DM made by Boston Micromachines Corporation for high-order correction. We present our on-going characterization of AO system performance. The AO-OCT system typically has residual wavefront error of 100 nm rms. The correctable error in the system is dominated by low-order error that we believe is introduced by aliasing in the control loop. Careful characterization of the AO system will lead to improved performance and inform the design of future systems.

We describe a compact MEMS-based adaptive optics (AO) optical coherence tomography (OCT) system with improved AO performance and ease of clinical use. A typical AO system consists of a Shack-Hartmann wavefront sensor and a deformable mirror that measures and corrects the ocular and system aberrations. Because of limitations on current deformable mirror technologies, the amount of real-time ocular-aberration compensation is restricted and small in previous AO-OCT instruments. In this instrument, we incorporate an optical apparatus to correct the spectacle aberrations of the patients such as myopia, hyperopia and astigmatism. This eliminates the tedious process of using trial lenses in clinical imaging. Different amount of spectacle aberration compensation was achieved by motorized stages and automated with the AO computer for ease of clinical use. In addition, the compact AO-OCT was optimized to have minimum system aberrations to reduce AO registration errors and improve AO performance.

Ultra-high isotropic resolution imaging of retinal structures was made possible with an adaptive optics system using dual deformable mirrors and a Fourier-domain optical coherence tomography (Fd-OCT) system with correction for longitudinal chromatic aberration. This system was used to image microscopic retinal structures of healthy as well as diseased retinas in vivo. The improved resolution and contrast enhanced visualization of morphological structures in the retina can be clearly seen. The benefits of this instrument are apparent from comparison of new images with those acquired using a previous generation AO-OCT instrument. Big change in the appearance of speckle field (reduction in speckle size) can be observed as well. Additionally, further improvements in volumetric data acquisition and image representation will be discussed. This includes creation of large Field of View (FOV) AO-OCT volume from multiple sub-volumes and its visualization. Also techniques and results of reducing speckle contrast by averaging multiple B-scans will be presented.

Adaptive optics scanning laser ophthalmoscopes have been used to produce noninvasive views of the human retina. However, the range of aberration compensation has been limited by the choice of deformable mirror technology. We demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human eye while maintaining the quality of the retinal imagery. We verified experimentally that the use of dual deformable mirrors improved the dynamic range for correction of the wavefront aberrations compared with the use of the micro-electro-mechanical-system mirror alone and improved the quality of the wavefront correction compared with the use of the bimorph mirror alone. We also demonstrated that the large-stroke bimorph deformable mirror improved the capability for axial sectioning with the confocal imaging system by providing an easier way to move the focus axially through different layers of the retina.

Adaptive optics (AO) coupled with ultra-fast spectral-domain optical coherence tomography (SD-OCT) has achieved the necessary 3D resolution, sensitivity, and speed for imaging the microscopic retina at the cellular level. While this technology has been rigorously applied to evaluating the 3D morphology of cone photoreceptors, similar detailed studies of cell-sized structures in the inner retina have yet to be undertaken. In this paper, we improve the technical performance of our AO ultrafast SD-OCT and investigate its use for imaging the microscopic inner retina, in particular the nerve fiber layer (NFL) and retinal capillary network. To maximize lateral resolution within the inner retina, focus was controlled with a high stroke, 37-actuator bimorph mirror (AOptix) that also served as the wavefront corrector of the AO. The AO system operated at a closed-loop rate of 25 Hz. The SD-OCT sub-system consisted of a superluminescent diode (l= 842 nm, Dl= 50 nm) and a 512 pixel line scan charge-coupled device (CCD) that acquired 72,000 A-scans/sec. Three different B-scan lengths (36, 60, and 120 A-scans/B-scan), which correspond to B-scan exposure durations of 0.5, 0.83, and 1.67 ms, were evaluated to determine the maximum B-scan length that could be tolerated without noticeable loss in image quality due to eye motion in the well fixated eye. Additional technical improvements included sub-pixel registration to remove instrument error and axial registration of the volume images. Small volume images were acquired at 2 and 7 degrees retinal eccentricity with focus systematically shifted through the retina. Small capillaries, some approaching the smallest in the human eye, were readily detected with AO SD-OCT. Appearance of the nerve fiber layer varied noticeably with depth. The most inner portion (presumably the inner limiting membrane) appeared as a thin irregular surface with little characteristic speckle noise. Within the NFL, complex striation patterns (presumably NFL bundles) were observed throughout the entire thickness with pattern density highest in the inner portion (~15 mm) and large corrugations (~35 mm) at the interface with the ganglion cell layer below. Speckle noise was significant throughout the NFL.

Ultrahigh axial resolution in adaptive optics - optical coherence tomography (AO-OCT) is fundamentally limited by the intrinsic chromatic aberrations of the human eye. Variation in refractive index of the ocular media with wavelength causes the spectral content of broadband light sources to focus at different depths in the retina for light entering the eye and at the imaging detector for light exiting. This effect has not been previously reported for ultrahigh-resolution OCT (without AO) likely because the effect is masked by the relatively long depth of focus dictated by the small pupils used in these systems. With AO, the pupil size is much larger and depth of focus substantially narrower. As such the chromatic aberrations of the eye can counteract the lateral resolution benefit of AO when used with broadband light sources. To more fully tap the potential of AO-OCT, compensation of the eye's chromatic and monochromatic aberrations must occur concurrently. One solution is to insert an achromatizing lens in front of the eye whose chromatic aberrations are equal but opposite in sign to that of the eye. In this paper we evaluate the efficacy of a novel design that uses a custom achromatizing lens placed near the fiber collimating optic. AO-OCT images are acquired on several subjects with and without the achromatizing lens and in combination with two light sources of different spectral width. The combination of the achromatizing lens and broadband light source yielded the sharpest images of the retina and the smallest speckle.

Two deformable mirrors (2DM) were used in an adaptive optics - optical coherence tomography (AO-OCT) system to image in vivo microscopic retinal structures of healthy and diseased retinas. As a result, multiple morphological structures not previously seen in vivo have been visualized. Among those presented are three-dimensional representations of the fovea and optic nerve head (ONH), revealing cellular structures and micro-vasculature. Drusen in macular degeneration and photoreceptor dystrophies are also presented. Different methods for displaying volumetric AO-OCT data to facilitate visualization of certain morphological details are compared.

Scanning laser ophthalmoscopes with adaptive optics (AOSLO) have been shown previously to provide a noninvasive, cellular-scale view of the living human retina. However, the clinical utility of these systems has been limited by the available deformable mirror technology. In this paper, we demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human retina, making the AOSLO system a viable, non-invasive, high-resolution imaging tool for clinical diagnostics. We used a bimorph deformable mirror to correct low-order aberrations with relatively large amplitudes. The bimorph mirror is manufactured by Aoptix, Inc. with 37 elements and 18 mm stroke in a 10 mm aperture. We used a MEMS deformable mirror to correct high-order aberrations with lower amplitudes. The MEMS mirror is manufactured by Boston Micromachine, Inc with 144 elements and 1.5 mm stroke in a 3 mm aperture. We have achieved near diffraction-limited retina images using the dual deformable mirrors to correct large aberrations up to ±3D of defocus and ±3D of cylindrical aberrations with test subjects. This increases the range of spectacle corrections by the AO systems by a factor of 10, which is crucial for use in the clinical environment. This ability for large phase compensation can eliminate accurate refractive error fitting for the patients, which greatly improves the system ease of use and efficiency in the clinical environment.

A high-stroke micromirror array was designed, modeled, fabricated and tested. Each pixel in the 4x4 array consists of a self-aligned vertical comb drive actuator that has had a single-crystal silicon mirror successfully bonded to it. Two different bonding technologies were used, photoresist bonding and fusion bonding. The results of each of these bonding methods will be presented. Analytical models combined w ith CoventorWare® simulations were used to design these elements that would move up to 10 mi crons in piston motion with 200V applied. Devices were fabricated according to this design and difference measurements performed with a white-light interferometer demonstrated a displacement of 0.18 microns with 200V applied. Further investigation reveal ed that fabrication process in accuracy led to significantly stiffer mechanical springs in the fabri cated devices. The increased stiffness of the springs was shown to account for the reduced displacement that was observed. Keywords: Adaptive optics, wavefront correction, micromechanical mirror device, piston-type mirror elements, comb drive actuators, large displacement micromirrors, sp atial light modulator, surface micromachining, MOEMS

The Solid-State, Heat-Capacity Laser (SSHCL) program at Lawrence Livermore National Laboratory is a multi-generation laser development effort scalable to the megawatt power levels with current performance approaching 100 kilowatts. This program is one of many designed to harness the power of lasers for use as directed energy weapons. There are many hurdles common to all of these programs that must be overcome to make the technology viable. There will be a in-depth discussion of the general issues facing state-of-the-art high energy lasers and paths to their resolution. Despite the relative simplicity of the SSHCL design, many challenges have been uncovered in the implementation of this particular system. An overview of these and their resolution are discussed. The overall system design of the SSHCL, technological strengths and weaknesses, and most recent experimental results will be presented.

We report first observations of the three-dimensional morphology of cone photoreceptors in the living human retina. Images were acquired with a high-speed adaptive optics (AO) spectral domain optical coherence tomography (SD-OCT) camera. The AO system consists of a Shack-Hartmann wavefront sensor and bimorph deformable mirror (AOptix) that measure and correct the ocular and system aberrations at a closed-loop rate of 12 Hz. Unlike previous AO-OCT and AOSLO instruments, the bimorph mirror was strategically positioned between the XY mechanical scanners and the subject's eye so as to avoid beam distortion at the pupil plane, which is created when the mirror compensates for the refractive error of the eye. This new configuration is evaluated empirically and with commercial ray tracing software. The SDOCT system consists of a superluminescent diode and a 512 pixel line scan charge-coupled device (CCD) that acquires 75,000 A-scans/sec. This rate is more than two times faster than that previously reported. Retina motion artifiacts were minimized by quickly acquiring small volume images of the retina with and without AO compensation. Camera sensitivity was sufficient to detect reflections from all major retinal layers. The distribution of bright spots observed within C-scans at the inner segment / outer segment (IS/OS) junction and at the posterior tips of the OS were found to be highly correlated with one another and with the expected cone spacing. No correlation was found between the IS/OS junction and either the plexiform layers or the layers immediately behind the OS posterior tips.

The Large Synoptic Survey Telescope (LSST) is a unique, three-mirror, modified Paul-Baker design with an 8.4m primary, a 3.4m secondary, and a 5.0m tertiary feeding a camera system that includes corrector optics to produce a 3.5 degree field of view with excellent image quality (

We are developing a new class of deformable optic based on electrostatic actuation of nanolaminate foils. These foils are engineered at the atomic level to provide optimal opto-mechanical properties, including surface quality, strength and stiffness, for a wide range of deformable optics. We are combining these foils, developed at Lawrence Livermore National Laboratory (LLNL), with commercial metal processing techniques to produce prototype deformable optics with aperture sizes up to 10 cm and actuator spacing from 1 mm to 1 cm and with a range of surface deformation designed to be as much as 10 microns. The existing capability for producing nanolaminate foils at LLNL, coupled with the commercial metal processing techniques being used, enable the potential production of these deformable optics with aperture sizes of over 1 m, and much larger deformable optics could potentially be produced by tiling multiple deformable segments. In addition, based on the fabrication processes being used, deformable nanolaminate optics could potentially be produced with areal densities of less than 1 kg per square m for applications in which lightweight deformable optics are desirable, and deformable nanolaminate optics could potentially be fabricated with intrinsically curved surfaces, including aspheric shapes. We will describe the basic principles of these devices, and we will present details of the design, fabrication and characterization of the prototype deformable nanolaminate optics that have been developed to date. We will also discuss the possibilities for future work on scaling these devices to larger sizes and developing both devices with lower areal densities and devices with curved surfaces.

The Large Synoptic Survey Telescope (LSST) is a three mirror modified Paul-Baker design with an 8.4m primary, a 3.4m secondary, and a 5.0m tertiary followed by a 3-element refractive corrector producing a 3.5 degree field of view. This design produces image diameters of

Adaptive Optics - Optical Coherence Tomography (AO-OCT) has demonstrated a promising improvement in lateral resolution for retinal imaging compared to standard OCT. Recent developments in Fourier-domain OCT technology allow AO-OCT instruments to acquire three-dimensional (3D) retinal structures with high speed and high "volumetric" resolution (in all three dimensions). One of the most important factors (besides acquisition speed) that will determine the true potential of this technique is its ability to achieve diffraction-limited lateral resolution (~3 μm) while operating in the ultrahigh axial resolution range (~3 μm) offered by OCT. Theoretical studies have shown that the eye's chromatic aberrations may drastically reduce volumetric resolution. This is a critical finding because for "standard" stand alone ultrahigh OCT, increasing the spectral bandwidth of the light source improves axial resolution without compromising lateral resolution. To study the effects of spectral bandwidth on AO-OCT systems for retinal imaging two different light sources offering 6 and 3 μm axial resolution were tested. This comparison was based on both AO correcting system performance as well as the quality of corresponding OCT images.