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Sample records for adaptive optics applications

  1. Applications of Adaptive Optics Scanning Laser Ophthalmoscopy

    PubMed Central

    Roorda, Austin

    2010-01-01

    Adaptive optics (AO) describes a set of tools to correct or control aberrations in any optical system. In the eye, AO allows for precise control of the ocular aberrations. If used to correct aberrations over a large pupil, for example, cellular level resolution in retinal images can be achieved. AO systems have been demonstrated for advanced ophthalmoscopy as well as for testing and/or improving vision. In fact, AO can be integrated to any ophthalmic instrument where the optics of the eye is involved, with a scope of applications ranging from phoropters to optical coherence tomography systems. In this paper, I discuss the applications and advantages of using AO in a specific system, the adaptive optics scanning laser ophthalmoscope, or AOSLO. Since the Borish award was, in part, awarded to me because of this effort, I felt it appropriate to select this as the topic for this paper. Furthermore, users of AOSLO continue to appreciate the benefits of the technology, some of which were not anticipated at the time of development, and so it is time to revisit this topic and summarize them in a single paper. PMID:20160657

  2. Adaptive Optics Retinal Imaging: Emerging Clinical Applications

    PubMed Central

    Godara, Pooja; Dubis, Adam M.; Roorda, Austin; Duncan, Jacque L.; Carroll, Joseph

    2010-01-01

    The human retina is a uniquely accessible tissue. Tools like scanning laser ophthalmoscopy (SLO) and spectral domain optical coherence tomography (SD-OCT) provide clinicians with remarkably clear pictures of the living retina. While the anterior optics of the eye permit such non-invasive visualization of the retina and associated pathology, these same optics induce significant aberrations that in most cases obviate cellular-resolution imaging. Adaptive optics (AO) imaging systems use active optical elements to compensate for aberrations in the optical path between the object and the camera. Applied to the human eye, AO allows direct visualization of individual rod and cone photoreceptor cells, RPE cells, and white blood cells. AO imaging has changed the way vision scientists and ophthalmologists see the retina, helping to clarify our understanding of retinal structure, function, and the etiology of various retinal pathologies. Here we review some of the advances made possible with AO imaging of the human retina, and discuss applications and future prospects for clinical imaging. PMID:21057346

  3. Adaptive optics retinal imaging: emerging clinical applications.

    PubMed

    Godara, Pooja; Dubis, Adam M; Roorda, Austin; Duncan, Jacque L; Carroll, Joseph

    2010-12-01

    The human retina is a uniquely accessible tissue. Tools like scanning laser ophthalmoscopy and spectral domain-optical coherence tomography provide clinicians with remarkably clear pictures of the living retina. Although the anterior optics of the eye permit such non-invasive visualization of the retina and associated pathology, the same optics induce significant aberrations that obviate cellular-resolution imaging in most cases. Adaptive optics (AO) imaging systems use active optical elements to compensate for aberrations in the optical path between the object and the camera. When applied to the human eye, AO allows direct visualization of individual rod and cone photoreceptor cells, retinal pigment epithelium cells, and white blood cells. AO imaging has changed the way vision scientists and ophthalmologists see the retina, helping to clarify our understanding of retinal structure, function, and the etiology of various retinal pathologies. Here, we review some of the advances that were made possible with AO imaging of the human retina and discuss applications and future prospects for clinical imaging.

  4. Adaptive optics ophthalmoscopy: results and applications.

    PubMed

    Pallikaris, A

    2005-01-01

    The living human eye's optical aberrations set a limit to retinal imaging in the clinical setting. Progress in the field of adaptive optics has offered unique solutions to this problem. The purpose of this review is to summarize the most recent advances in adaptive optics ophthalmoscopy. Adaptive optics technology has been combined with flood illumination imaging, confocal scanning laser ophthalmoscopy, and optical coherence tomography for the high resolution imaging of the retina. The advent of adaptive optics technology has provided the technical platform for the compensation of the eye's aberration and made possible the observation of single cones, small capillaries, nerve fibers, and leukocyte dynamics as well as the ultrastructure of the optic nerve head lamina cribrosa in vivo. Detailed imaging of retinal infrastructure provides valuable information for the study of retinal physiology and pathology.

  5. Adaptive Optics Applications in Vision Science

    SciTech Connect

    Olivier, S S

    2003-03-17

    Adaptive optics can be used to correct the aberrations in the human eye caused by imperfections in the cornea and the lens and thereby, improve image quality both looking into and out of the eye. Under the auspices of the NSF Center for Adaptive Optics and the DOE Biomedical Engineering Program, Lawrence Livermore National Laboratory has joined together with leading vision science researchers around the country to develop and test new ophthalmic imaging systems using novel wavefront corrector technologies. Results of preliminary comparative evaluations of these technologies in initial system tests show promise for future clinical utility.

  6. Adaptive holography for optical sensing applications

    NASA Astrophysics Data System (ADS)

    Residori, S.; Bortolozzo, U.; Peigné, A.; Molin, S.; Nouchi, P.; Dolfi, D.; Huignard, J. P.

    2016-03-01

    Adaptive holography is a promising method for high sensitivity phase modulation measurements in the presence of slow perturbations from the environment. The technique is based on the use of a nonlinear recombining medium, here an optically addressed spatial light modulator specifically realized to operate at 1.55 μm. Owing to the physical mechanisms involved, the interferometer adapts to slow phase variations within a range of 5-10 Hz, thus filtering out low frequency noise while transmitting higher frequency phase modulations. We present the basic principles of the adaptive interferometer and show that it can be used in association with a sensing fiber in order to detect phase modulations. Finally, a phase-OTDR architecture using the adaptive holographic interferometer is presented and shown to allows the detection of localized perturbations along the sensing fiber.

  7. Adaptive optics and phase diversity imaging for responsive space applications.

    SciTech Connect

    Smith, Mark William; Wick, David Victor

    2004-11-01

    The combination of phase diversity and adaptive optics offers great flexibility. Phase diverse images can be used to diagnose aberrations and then provide feedback control to the optics to correct the aberrations. Alternatively, phase diversity can be used to partially compensate for aberrations during post-detection image processing. The adaptive optic can produce simple defocus or more complex types of phase diversity. This report presents an analysis, based on numerical simulations, of the efficiency of different modes of phase diversity with respect to compensating for specific aberrations during post-processing. It also comments on the efficiency of post-processing versus direct aberration correction. The construction of a bench top optical system that uses a membrane mirror as an active optic is described. The results of characterization tests performed on the bench top optical system are presented. The work described in this report was conducted to explore the use of adaptive optics and phase diversity imaging for responsive space applications.

  8. Astronomy Applications of Adaptive Optics at Lawrence Livermore National Laboratory

    SciTech Connect

    Bauman, B J; Gavel, D T

    2003-04-23

    Astronomical applications of adaptive optics at Lawrence Livermore National Laboratory (LLNL) has a history that extends from 1984. The program started with the Lick Observatory Adaptive Optics system and has progressed through the years to lever-larger telescopes: Keck, and now the proposed CELT (California Extremely Large Telescope) 30m telescope. LLNL AO continues to be at the forefront of AO development and science.

  9. Laser beacon adaptive optics for power beaming applications

    NASA Astrophysics Data System (ADS)

    Fugate, Robert Q.

    1994-05-01

    This paper discusses the laser beam control system requirements for power beaming applications. Power beaming applications include electric and thermal engine propulsion for orbit transfer, station changing, and recharging batteries. Beam control includes satellite acquisition, high accuracy tracking, higher order atmospheric compensation using adaptive optics, and precision point-ahead. Beam control may also include local laser beam clean-up with a low order adaptive optics system. This paper also presents results of tracking and higher-order correction experiments on astronomical objects. The results were obtained with a laser beacon adaptive optics system at Phillips Laboratory's Starfire Optical Range near Albuquerque, NM. At a wavelength of 0.85 micrometers , we have achieved Strehl ratios of approximately 0.50 using laser beacons and approximately 0.65 using natural stars for exposures longer than one minute on objects of approximately 8th magnitude. The resulting point spread function has a full width half maximum (FWHM) of 0.13 arcsec.

  10. Wavefront Control for Space Telescope Applications Using Adaptive Optics

    DTIC Science & Technology

    2007-12-01

    SPACE TELESCOPE APPLICATIONS USING ADAPTIVE OPTICS by Matthew R. Allen December 2007 Thesis Advisor: Brij Agrawal Second Reader...ASTRONAUTICAL ENGINEERING from the NAVAL POSTGRADUATE SCHOOL December 2007 Author: Matthew R. Allen Approved by: Dr, Brij Agrawal...34 3. Direct Iterative Zonal Feedback Control ........................................ 35 4. Direct Iterative

  11. Laser beacon adaptive optics for power beaming applications

    SciTech Connect

    Fugate, R.Q.

    1994-12-31

    This paper discusses the laser beam control system requirements for power beaming applications. Power beaming applications include electric and thermal engine propulsion for orbit transfer, station changing, and recharging batteries. Beam control includes satellite acquisition, high accuracy tracking, higher order atmospheric compensation using adaptive optics, and precision point-ahead. Beam control may also include local laser beam clean-up with a low order adaptive optics system. This paper also presents results of tracking and higher-order correction experiments on astronomical objects. The results were obtained with a laser beacon adaptive optics system at Phillips Laboratory`s Starfire Optical Range near Albuquerque, NM. At a wavelength of 0.85 {mu}m, the author has achieved Strehl ratios of {approximately}0.50 using laser beacons and {approximately}0.65 using natural stars for exposures longer than one minute on objects of {approximately}8{sup th} magnitude. The resulting point spread function has a full width half maximum (FWHM) of 0.13 arcsec.

  12. Adaptive optics ophthalmoscopy.

    PubMed

    Roorda, A

    2000-01-01

    Retinal images in the human eye are normally degraded because we are forced to use the optical system of the human eye--which is fraught with aberrations--as the objective lens. The recent application of adaptive optics technology to measure and compensate for these aberrations has produced retinal images in human eyes with unprecedented resolution. The adaptive optics ophthalmoscope is used to take pictures of photoreceptors and capillaries and to study spectral and angular tuning properties of individual photoreceptors. Application of adaptive optics technology for ophthalmoscopy promises continued progress toward understanding the basic properties of the living human retina and also for clinical applications.

  13. A Review of Adaptive Optics Optical Coherence Tomography: Technical Advances, Scientific Applications, and the Future.

    PubMed

    Jonnal, Ravi S; Kocaoglu, Omer P; Zawadzki, Robert J; Liu, Zhuolin; Miller, Donald T; Werner, John S

    2016-07-01

    Optical coherence tomography (OCT) has enabled "virtual biopsy" of the living human retina, revolutionizing both basic retina research and clinical practice over the past 25 years. For most of those years, in parallel, adaptive optics (AO) has been used to improve the transverse resolution of ophthalmoscopes to foster in vivo study of the retina at the microscopic level. Here, we review work done over the last 15 years to combine the microscopic transverse resolution of AO with the microscopic axial resolution of OCT, building AO-OCT systems with the highest three-dimensional resolution of any existing retinal imaging modality. We surveyed the literature to identify the most influential antecedent work, important milestones in the development of AO-OCT technology, its applications that have yielded new knowledge, research areas into which it may productively expand, and nascent applications that have the potential to grow. Initial efforts focused on demonstrating three-dimensional resolution. Since then, many improvements have been made in resolution and speed, as well as other enhancements of acquisition and postprocessing techniques. Progress on these fronts has produced numerous discoveries about the anatomy, function, and optical properties of the retina. Adaptive optics OCT continues to evolve technically and to contribute to our basic and clinical knowledge of the retina. Due to its capacity to reveal cellular and microscopic detail invisible to clinical OCT systems, it is an ideal companion to those instruments and has the demonstrable potential to produce images that can guide the interpretation of clinical findings.

  14. Objective assessment of image quality. IV. Application to adaptive optics

    NASA Astrophysics Data System (ADS)

    Barrett, Harrison H.; Myers, Kyle J.; Devaney, Nicholas; Dainty, Christopher

    2006-12-01

    The methodology of objective assessment, which defines image quality in terms of the performance of specific observers on specific tasks of interest, is extended to temporal sequences of images with random point spread functions and applied to adaptive imaging in astronomy. The tasks considered include both detection and estimation, and the observers are the optimal linear discriminant (Hotelling observer) and the optimal linear estimator (Wiener). A general theory of first- and second-order spatiotemporal statistics in adaptive optics is developed. It is shown that the covariance matrix can be rigorously decomposed into three terms representing the effect of measurement noise, random point spread function, and random nature of the astronomical scene. Figures of merit are developed, and computational methods are discussed.

  15. Objective assessment of image quality. IV. Application to adaptive optics.

    PubMed

    Barrett, Harrison H; Myers, Kyle J; Devaney, Nicholas; Dainty, Christopher

    2006-12-01

    The methodology of objective assessment, which defines image quality in terms of the performance of specific observers on specific tasks of interest, is extended to temporal sequences of images with random point spread functions and applied to adaptive imaging in astronomy. The tasks considered include both detection and estimation, and the observers are the optimal linear discriminant (Hotelling observer) and the optimal linear estimator (Wiener). A general theory of first- and second-order spatiotemporal statistics in adaptive optics is developed. It is shown that the covariance matrix can be rigorously decomposed into three terms representing the effect of measurement noise, random point spread function, and random nature of the astronomical scene. Figures of merit are developed, and computational methods are discussed.

  16. Objective assessment of image quality. IV. Application to adaptive optics

    PubMed Central

    Barrett, Harrison H.; Myers, Kyle J.; Devaney, Nicholas; Dainty, Christopher

    2008-01-01

    The methodology of objective assessment, which defines image quality in terms of the performance of specific observers on specific tasks of interest, is extended to temporal sequences of images with random point spread functions and applied to adaptive imaging in astronomy. The tasks considered include both detection and estimation, and the observers are the optimal linear discriminant (Hotelling observer) and the optimal linear estimator (Wiener). A general theory of first- and second-order spatiotemporal statistics in adaptive optics is developed. It is shown that the covariance matrix can be rigorously decomposed into three terms representing the effect of measurement noise, random point spread function, and random nature of the astronomical scene. Figures of merit are developed, and computational methods are discussed. PMID:17106464

  17. The development of an adaptive optics system and its application to biological microscope

    NASA Astrophysics Data System (ADS)

    Hattori, Masayuki; Tamada, Yosuke

    2016-10-01

    The improvement of the optical devices in this decade, such as the MEMS-SLM ( Micro Electro Mechanical Systems- Spatial Light Modulator ) and wave front sensor with micro lens device, is making adaptive optics commonly available. It also gives the new basis of the design of adaptive optics with the improved accuracy and the compactness. We have developed an adaptive optics bench from such a point of view, and the application to the optical microscope has attained effective results in the observation of the live cell samples. In this presentation, our recent results will be shown. The result includes analysis of blur by the fine structures in biological sample and result of the image correction by the adaptive optics.

  18. A Review of Adaptive Optics Optical Coherence Tomography: Technical Advances, Scientific Applications, and the Future

    PubMed Central

    Jonnal, Ravi S.; Kocaoglu, Omer P.; Zawadzki, Robert J.; Liu, Zhuolin; Miller, Donald T.; Werner, John S.

    2016-01-01

    Purpose Optical coherence tomography (OCT) has enabled “virtual biopsy” of the living human retina, revolutionizing both basic retina research and clinical practice over the past 25 years. For most of those years, in parallel, adaptive optics (AO) has been used to improve the transverse resolution of ophthalmoscopes to foster in vivo study of the retina at the microscopic level. Here, we review work done over the last 15 years to combine the microscopic transverse resolution of AO with the microscopic axial resolution of OCT, building AO-OCT systems with the highest three-dimensional resolution of any existing retinal imaging modality. Methods We surveyed the literature to identify the most influential antecedent work, important milestones in the development of AO-OCT technology, its applications that have yielded new knowledge, research areas into which it may productively expand, and nascent applications that have the potential to grow. Results Initial efforts focused on demonstrating three-dimensional resolution. Since then, many improvements have been made in resolution and speed, as well as other enhancements of acquisition and postprocessing techniques. Progress on these fronts has produced numerous discoveries about the anatomy, function, and optical properties of the retina. Conclusions Adaptive optics OCT continues to evolve technically and to contribute to our basic and clinical knowledge of the retina. Due to its capacity to reveal cellular and microscopic detail invisible to clinical OCT systems, it is an ideal companion to those instruments and has the demonstrable potential to produce images that can guide the interpretation of clinical findings. PMID:27409507

  19. Magnetic smart material application to adaptive x-ray optics

    NASA Astrophysics Data System (ADS)

    Ulmer, M. P.; Graham, Michael E.; Vaynman, Semyon; Cao, J.; Takacs, Peter Z.

    2010-09-01

    We discuss a technique of shape modification that can be applied to thin walled ({100-400 micron thickness) electroformed replicated optics or slumped glass optics to improve the near net shape of the mirror as well as the midfrequency ripple. The process involves sputter deposition of a magnetic smart material (MSM) film onto a permanently magnetic material. The MSM material exhibits strains about 400 times stronger than ordinary ferromagnetic materials. The deformation process involves a magnetic write head which traverses the surface, and under the guidance of active metrology feedback, locally magnetizes the surface to impart strain where needed. Designs and basic concepts as applied to space borne X-ray optics will be described.

  20. Characterization of a tunable astigmatic fluidic lens with adaptive optics correction for compact phoropter application

    NASA Astrophysics Data System (ADS)

    Fuh, Yiin-Kuen; Huang, Chieh-Tse

    2014-07-01

    Fluidically controlled lenses which adaptively correct prescribed refractive error without mechanically moving parts are extensively applied in the ophthalmic applications. Capable of variable-focusing properties, however, the associated aberrations due to curvature change and refractive index mismatch can inherently degrade image quality severely. Here we present the experimental study of the aberrations in tunable astigmatic lens and use of adaptive optics to compensate for the wavefront errors. Characterization of the optical properties of the individual lenses is carried out by Shack-Hartmann measurements. An adaptive optics (AO) based scheme is demonstrated for three injected fluidic volumes, resulting in a substantial reduction of the wavefront errors from -0.12, -0.25, -0.32 to 0.01, -0.01, -0.20 μm, respectively, corresponding to the optical power tenability of 0.83 to 1.84 D. Furthermore, an integrated optical phoroptor consisting of adjustable astigmatic lenses and AO correction is demonstrated such that an induced refraction error of -1 D cylinder at 180° of a model eye vision is experimentally corrected.

  1. Holographic Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Andersen, G.

    For the last two decades adaptive optics has been used as a technique for correcting imaging applications and directed energy/laser targeting and laser communications systems affected by atmospheric turbulence. Typically these systems are bulky and limited to <10 kHz due to large computing overhead and limited photon efficiencies. Moreover most use zonal wavefront sensors which cannot easily handle extreme scintillation or unexpected obscuration of a pre-set aperture. Here we present a compact, lightweight adaptive optics system with the potential to operate at speeds of MHz. The system utilizes a hologram to perform an all-optical wavefront analysis that removes the need for any computer. Finally, the sensing is made on a modal basis so it is largely insensitive to scintillation and obscuration. We have constructed a prototype device and will present experimental results from our research. The holographic adaptive optics system begins with the creation of a multiplexed hologram. This hologram is created by recording the maximum and minimum response functions of every actuator in the deformable mirror against a unique focused reference beam. When a wavefront of some arbitrary phase is incident on the processed hologram, a number of focal spots are created -- one pair for each actuator in the DM. The absolute phase error at each particular actuator location is simply related to the ratio of the intensity of each pair of spots. In this way we can use an array of photodetectors to give a direct readout of phase error without the need for any calculations. The advantages of holographic adaptive optics are many. To begin with, the measurement of phase error is made all optically, so the wavefront sensor directly controls the actuators in the DM without any computers. Using fast, photon counting photodetectors allows for closed loop correction limited only by the speed of the deformable mirror which in the case of MEMS devices can be 100 kHz or more. All this can be

  2. Telescope Adaptive Optics Code

    SciTech Connect

    Phillion, D.

    2005-07-28

    The Telescope AO Code has general adaptive optics capabilities plus specialized models for three telescopes with either adaptive optics or active optics systems. It has the capability to generate either single-layer or distributed Kolmogorov turbulence phase screens using the FFT. Missing low order spatial frequencies are added using the Karhunen-Loeve expansion. The phase structure curve is extremely dose to the theoreUcal. Secondly, it has the capability to simulate an adaptive optics control systems. The default parameters are those of the Keck II adaptive optics system. Thirdly, it has a general wave optics capability to model the science camera halo due to scintillation from atmospheric turbulence and the telescope optics. Although this capability was implemented for the Gemini telescopes, the only default parameter specific to the Gemini telescopes is the primary mirror diameter. Finally, it has a model for the LSST active optics alignment strategy. This last model is highly specific to the LSST

  3. [Adaptive optics for ophthalmology].

    PubMed

    Saleh, M

    2016-04-01

    Adaptive optics is a technology enhancing the visual performance of an optical system by correcting its optical aberrations. Adaptive optics have already enabled several breakthroughs in the field of visual sciences, such as improvement of visual acuity in normal and diseased eyes beyond physiologic limits, and the correction of presbyopia. Adaptive optics technology also provides high-resolution, in vivo imaging of the retina that may eventually help to detect the onset of retinal conditions at an early stage and provide better assessment of treatment efficacy. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  4. Adaptive optics simulations for imaging with the Large Binocular Telescope interferometer: a first application

    NASA Astrophysics Data System (ADS)

    Carbillet, Marcel; Correia, Serge; Femenia, Bruno; Riccardi, Armando

    2000-07-01

    In this contribution we present a first application of the ongoing numerical simulations that are carried out in order to study the adaptive optics (AO) correction and the subsequent imaging post-processing when observing with the Large Binocular Telescope (LBT) interferometer. The simulation tool used as a starting point for this study is the software package CAOS 2.0 (Code for Adaptive Optics Systems, version 2.0), for its AO-simulation capabilities and its modular structure. It is used here in order to generate the turbulence-corrupted and subsequently adaptive-optics- corrected interferometric point-spread functions corresponding to the simultaneous observation of both a scientific object and a reference star, for three parallactic angles corresponding to three observation runs during the night. The obtained data are therefore used as the inputs of a multiple deconvolution method planned for imaging with the LBT interferometer. As an example, we have simulated the observation, in the R-band, of a Betelgeuse-like stellar object of 15th magnitude, 30 mas diameter, and with a 3 mas bright spot, under two different conditions of turbulence and AO-correction (leading to Strehl ratios of approximately 0.15 and approximately 0.45, respectively). Final results are found to be very encouraging.

  5. Retinal Imaging: Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Goncharov, A. S.; Iroshnikov, N. G.; Larichev, Andrey V.

    This chapter describes several factors influencing the performance of ophthalmic diagnostic systems with adaptive optics compensation of human eye aberration. Particular attention is paid to speckle modulation, temporal behavior of aberrations, and anisoplanatic effects. The implementation of a fundus camera with adaptive optics is considered.

  6. Adaptation of adaptive optics systems.

    NASA Astrophysics Data System (ADS)

    Xin, Yu; Zhao, Dazun; Li, Chen

    1997-10-01

    In the paper, a concept of an adaptation of adaptive optical system (AAOS) is proposed. The AAOS has certain real time optimization ability against the variation of the brightness of detected objects m, atmospheric coherence length rO and atmospheric time constant τ by means of changing subaperture number and diameter, dynamic range, and system's temporal response. The necessity of AAOS using a Hartmann-Shack wavefront sensor and some technical approaches are discussed. Scheme and simulation of an AAOS with variable subaperture ability by use of both hardware and software are presented as an example of the system.

  7. Wavefront phase retrieval with multi-aperture Zernike filter for atmospheric sensing and adaptive optics applications

    NASA Astrophysics Data System (ADS)

    Bordbar, Behzad; Farwell, Nathan H.; Vorontsov, Mikhail A.

    2016-09-01

    A novel scintillation resistant wavefront sensor based on a densely packed array of classical Zernike filters, referred to as the multi-aperture Zernike wavefront sensor (MAZ-WFS), is introduced and analyzed through numerical simulations. Wavefront phase reconstruction in the MAZ-WFS is performed using iterative algorithms that are optimized for phase aberration sensing in severe atmospheric turbulence conditions. The results demonstrate the potential of the MAZ-WFS for high-resolution retrieval of turbulence-induced phase aberrations in strong scintillation conditions for atmospheric sensing and adaptive optics applications.

  8. Closed-loop adaptive optics using a spatial light modulator for sensing and compensating of optical aberrations in ophthalmic applications

    NASA Astrophysics Data System (ADS)

    Akondi, Vyas; Jewel, Md. Atikur Rahman; Vohnsen, Brian

    2014-09-01

    Sensing and compensating of optical aberrations in closed-loop mode using a single spatial light modulator (SLM) for ophthalmic applications is demonstrated. Notwithstanding the disadvantages of the SLM, in certain cases, this multitasking capability of the device makes it advantageous over existing deformable mirrors (DMs), which are expensive and in general used for aberration compensation alone. A closed-loop adaptive optics (AO) system based on a single SLM was built. Beam resizing optics were used to utilize the large active area of the device and hence make it feasible to generate 137 active subapertures for wavefront sensing. While correcting Zernike aberrations up to fourth order introduced with the help of a DM (for testing purposes), diffraction-limited resolution was achieved. It is shown that matched filter and intensity-weighted centroiding techniques stand out among others. Closed-loop wavefront correction of aberrations in backscattered light from the eyes of three healthy human subjects was demonstrated after satisfactory results were obtained using an artificial eye, which was simulated with a short focal length lens and a sheet of white paper as diffuser. It is shown that the closed-loop AO system based on a single SLM is capable of diffraction-limited correction for ophthalmic applications.

  9. SPARTA: the ESO standard platform for adaptive optics real time applications

    NASA Astrophysics Data System (ADS)

    Fedrigo, Enrico; Donaldson, Robert; Soenke, Christian; Myers, Richard; Goodsell, Stephen; Geng, Deli; Saunter, Chris; Dipper, Nigel

    2006-06-01

    ESO is starting a number of new projects collectively called Second Generation VLT instrumentation. Several of them will use Adaptive Optics (AO). In comparison with today's ESO AO systems, the 2nd Generation VLT AO systems will be much bigger (in terms of degrees of freedom) and faster (in terms of loop frequency). Consequently the Real-Time Computer controlling these AO systems will be significantly bigger and more challenging to build compared with today's AO systems in operation. To support the new requirements ESO started the development of a common flexible platform called SPARTA for Standard Platform for Adaptive optics Real Time Applications. The guidelines along which SPARTA is developed recognize the importance of industry standards over custom development to lower the development costs, ease the maintenance and make the system upgradeable thus delivering the performance required. SPARTA is based on a hybrid architecture that comprises all the major computing architectures available today: the high computational throughput is achieved through the combination of FPGA and DSP usage, where DSP are used as fast coprocessors and FPGA are used as front and as communication infrastructure, thus guaranteeing also the low latency. The flexibility is spread between the usage of both high-end CPUs and again the DSPs. All three technologies are organized in a parallel system interconnected by fast serial fabrics based on standard protocols. External input / output interfaces are also based on industry standard protocols, thus enabling the usage of commercially available tools for development and testing.

  10. Adaptive Optics for Large Telescopes

    SciTech Connect

    Olivier, S

    2008-06-27

    The use of adaptive optics was originally conceived by astronomers seeking to correct the blurring of images made with large telescopes due to the effects of atmospheric turbulence. The basic idea is to use a device, a wave front corrector, to adjust the phase of light passing through an optical system, based on some measurement of the spatial variation of the phase transverse to the light propagation direction, using a wave front sensor. Although the original concept was intended for application to astronomical imaging, the technique can be more generally applied. For instance, adaptive optics systems have been used for several decades to correct for aberrations in high-power laser systems. At Lawrence Livermore National Laboratory (LLNL), the world's largest laser system, the National Ignition Facility, uses adaptive optics to correct for aberrations in each of the 192 beams, all of which must be precisely focused on a millimeter scale target in order to perform nuclear physics experiments.

  11. Large-Stroke Self-Aligned Vertical Comb Drive Actuators for Adaptive Optics Applications

    SciTech Connect

    Carr, E J; Olivier, S S; Solgaard, O

    2005-10-27

    A high-stroke micro-actuator array was designed, modeled, fabricated and tested. Each pixel in the 4x4 array consists of a self-aligned vertical comb drive actuator. This micro-actuator array was designed to become the foundation of a micro-mirror array that will be used as a deformable mirror for adaptive optics applications. Analytical models combined with CoventorWare{reg_sign} simulations were used to design actuators that would move up to 10{micro}m in piston motion with 100V applied. Devices were fabricated according to this design and testing of these devices demonstrated an actuator displacement of 1.4{micro}m with 200V applied. Further investigation revealed that fabrication process inaccuracy led to significantly stiffer mechanical springs in the fabricated devices. The increased stiffness of the springs was shown to account for the reduced displacement of the actuators relative to the design.

  12. 3-D Adaptive Sparsity Based Image Compression with Applications to Optical Coherence Tomography

    PubMed Central

    Fang, Leyuan; Li, Shutao; Kang, Xudong; Izatt, Joseph A.; Farsiu, Sina

    2015-01-01

    We present a novel general-purpose compression method for tomographic images, termed 3D adaptive sparse representation based compression (3D-ASRC). In this paper, we focus on applications of 3D-ASRC for the compression of ophthalmic 3D optical coherence tomography (OCT) images. The 3D-ASRC algorithm exploits correlations among adjacent OCT images to improve compression performance, yet is sensitive to preserving their differences. Due to the inherent denoising mechanism of the sparsity based 3D-ASRC, the quality of the compressed images are often better than the raw images they are based on. Experiments on clinical-grade retinal OCT images demonstrate the superiority of the proposed 3D-ASRC over other well-known compression methods. PMID:25561591

  13. Solar tomography adaptive optics.

    PubMed

    Ren, Deqing; Zhu, Yongtian; Zhang, Xi; Dou, Jiangpei; Zhao, Gang

    2014-03-10

    Conventional solar adaptive optics uses one deformable mirror (DM) and one guide star for wave-front sensing, which seriously limits high-resolution imaging over a large field of view (FOV). Recent progress toward multiconjugate adaptive optics indicates that atmosphere turbulence induced wave-front distortion at different altitudes can be reconstructed by using multiple guide stars. To maximize the performance over a large FOV, we propose a solar tomography adaptive optics (TAO) system that uses tomographic wave-front information and uses one DM. We show that by fully taking advantage of the knowledge of three-dimensional wave-front distribution, a classical solar adaptive optics with one DM can provide an extra performance gain for high-resolution imaging over a large FOV in the near infrared. The TAO will allow existing one-deformable-mirror solar adaptive optics to deliver better performance over a large FOV for high-resolution magnetic field investigation, where solar activities occur in a two-dimensional field up to 60'', and where the near infrared is superior to the visible in terms of magnetic field sensitivity.

  14. Solar Adaptive Optics.

    PubMed

    Rimmele, Thomas R; Marino, Jose

    Adaptive optics (AO) has become an indispensable tool at ground-based solar telescopes. AO enables the ground-based observer to overcome the adverse effects of atmospheric seeing and obtain diffraction limited observations. Over the last decade adaptive optics systems have been deployed at major ground-based solar telescopes and revitalized ground-based solar astronomy. The relatively small aperture of solar telescopes and the bright source make solar AO possible for visible wavelengths where the majority of solar observations are still performed. Solar AO systems enable diffraction limited observations of the Sun for a significant fraction of the available observing time at ground-based solar telescopes, which often have a larger aperture than equivalent space based observatories, such as HINODE. New ground breaking scientific results have been achieved with solar adaptive optics and this trend continues. New large aperture telescopes are currently being deployed or are under construction. With the aid of solar AO these telescopes will obtain observations of the highly structured and dynamic solar atmosphere with unprecedented resolution. This paper reviews solar adaptive optics techniques and summarizes the recent progress in the field of solar adaptive optics. An outlook to future solar AO developments, including a discussion of Multi-Conjugate AO (MCAO) and Ground-Layer AO (GLAO) will be given.

  15. Review of adaptive optics OCT (AO-OCT): principles and applications for retinal imaging [Invited

    PubMed Central

    Pircher, Michael; Zawadzki, Robert J

    2017-01-01

    In vivo imaging of the human retina with a resolution that allows visualization of cellular structures has proven to be essential to broaden our knowledge about the physiology of this precious and very complex neural tissue that enables the first steps in vision. Many pathologic changes originate from functional and structural alterations on a cellular scale, long before any degradation in vision can be noted. Therefore, it is important to investigate these tissues with a sufficient level of detail in order to better understand associated disease development or the effects of therapeutic intervention. Optical retinal imaging modalities rely on the optical elements of the eye itself (mainly the cornea and lens) to produce retinal images and are therefore affected by the specific arrangement of these elements and possible imperfections in curvature. Thus, aberrations are introduced to the imaging light and image quality is degraded. To compensate for these aberrations, adaptive optics (AO), a technology initially developed in astronomy, has been utilized. However, the axial sectioning provided by retinal AO-based fundus cameras and scanning laser ophthalmoscope instruments is limited to tens of micrometers because of the rather small available numerical aperture of the eye. To overcome this limitation and thus achieve much higher axial sectioning in the order of 2-5µm, AO has been combined with optical coherence tomography (OCT) into AO-OCT. This enabled for the first time in vivo volumetric retinal imaging with high isotropic resolution. This article summarizes the technical aspects of AO-OCT and provides an overview on its various implementations and some of its clinical applications. In addition, latest developments in the field, such as computational AO-OCT and wavefront sensor less AO-OCT, are covered. PMID:28663890

  16. Review of adaptive optics OCT (AO-OCT): principles and applications for retinal imaging [Invited].

    PubMed

    Pircher, Michael; Zawadzki, Robert J

    2017-05-01

    In vivo imaging of the human retina with a resolution that allows visualization of cellular structures has proven to be essential to broaden our knowledge about the physiology of this precious and very complex neural tissue that enables the first steps in vision. Many pathologic changes originate from functional and structural alterations on a cellular scale, long before any degradation in vision can be noted. Therefore, it is important to investigate these tissues with a sufficient level of detail in order to better understand associated disease development or the effects of therapeutic intervention. Optical retinal imaging modalities rely on the optical elements of the eye itself (mainly the cornea and lens) to produce retinal images and are therefore affected by the specific arrangement of these elements and possible imperfections in curvature. Thus, aberrations are introduced to the imaging light and image quality is degraded. To compensate for these aberrations, adaptive optics (AO), a technology initially developed in astronomy, has been utilized. However, the axial sectioning provided by retinal AO-based fundus cameras and scanning laser ophthalmoscope instruments is limited to tens of micrometers because of the rather small available numerical aperture of the eye. To overcome this limitation and thus achieve much higher axial sectioning in the order of 2-5µm, AO has been combined with optical coherence tomography (OCT) into AO-OCT. This enabled for the first time in vivo volumetric retinal imaging with high isotropic resolution. This article summarizes the technical aspects of AO-OCT and provides an overview on its various implementations and some of its clinical applications. In addition, latest developments in the field, such as computational AO-OCT and wavefront sensor less AO-OCT, are covered.

  17. Adaptive optical zoom sensor.

    SciTech Connect

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

    2005-11-01

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

  18. Further Studies on Nonlinear Adaptive Optics,

    DTIC Science & Technology

    1981-04-01

    AD-A9 167 SCIENCE APPLICATIONS INC LA JOLLA CA F/9 20/6 A-A*9 16 FURTHER STUDIES ON NONLINEAR ADAPTIVE OPTICS , 1W _ ASFE APR SI A ELCI. J1 NAGEL. D...FURTHER STUDIES ON NONLINEAR ADAPTIVE OPTICS Apr 8l 7 Submitted to: Director of Physics Air Force Office of Scientific Research ATTN: NP Bldg. 410...1 I STATEMENT OF WORK ...... .. .................... I-I II NONLINEAR ADAPTIVE OPTICS SUMMARY

  19. Intelligent Optical Systems Using Adaptive Optics

    NASA Technical Reports Server (NTRS)

    Clark, Natalie

    2012-01-01

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

  20. Adaptive wavelet analysis of optical coherent tomography data: Application in problems of diagnostics

    NASA Astrophysics Data System (ADS)

    Nazimov, A. I.; Pavlov, A. N.; Lychagov, V. V.; Semyachkina-Glushkovskaya, O. V.

    2013-10-01

    A method of adaptive wavelet analysis permitting one to set parameters of the wavelet transform based on principles of the optimization theory is proposed. Applying the method to optical coherent tomography data processing is considered. The efficiency of the proposed method for diagnosing functional disorders in the dynamics of cerebral vessels is illustrated.

  1. Advanced Adaptive Optics Control Techniques

    DTIC Science & Technology

    1979-01-01

    Optimal estimation and control methods for high energy laser adaptive optics systems are described. Three system types are examined: Active...the adaptive optics approaches and potential system implementations are recommended.

  2. Advanced Adaptive Optics Technology Development

    SciTech Connect

    Olivier, S

    2001-09-18

    The NSF Center for Adaptive Optics (CfAO) is supporting research on advanced adaptive optics technologies. CfAO research activities include development and characterization of micro-electro-mechanical systems (MEMS) deformable mirror (DM) technology, as well as development and characterization of high-resolution adaptive optics systems using liquid crystal (LC) spatial light modulator (SLM) technology. This paper presents an overview of the CfAO advanced adaptive optics technology development activities including current status and future plans.

  3. Adaptive optics ophthalmoscopy.

    PubMed

    Roorda, Austin; Duncan, Jacque L

    2015-11-01

    This review starts with a brief history and description of adaptive optics (AO) technology, followed by a showcase of the latest capabilities of AO systems for imaging the human retina and an extensive review of the literature on where AO is being used clinically. The review concludes with a discussion on future directions and guidance on usage and interpretation of images from AO systems for the eye.

  4. Adaptive optics ophthalmoscopy

    PubMed Central

    Roorda, Austin; Duncan, Jacque L.

    2016-01-01

    This review starts with a brief history and description of adaptive optics (AO) technology, followed by a showcase of the latest capabilities of AO systems for imaging the human retina and an extensive review of the literature on where AO is being used clinically. The review concludes with a discussion on future directions and guidance on usage and interpretation of images from AO systems for the eye. PMID:26973867

  5. Algorithm for localized adaptive diffuse optical tomography and its application in bioluminescence tomography

    NASA Astrophysics Data System (ADS)

    Naser, Mohamed A.; Patterson, Michael S.; Wong, John W.

    2014-04-01

    A reconstruction algorithm for diffuse optical tomography based on diffusion theory and finite element method is described. The algorithm reconstructs the optical properties in a permissible domain or region-of-interest to reduce the number of unknowns. The algorithm can be used to reconstruct optical properties for a segmented object (where a CT-scan or MRI is available) or a non-segmented object. For the latter, an adaptive segmentation algorithm merges contiguous regions with similar optical properties thereby reducing the number of unknowns. In calculating the Jacobian matrix the algorithm uses an efficient direct method so the required time is comparable to that needed for a single forward calculation. The reconstructed optical properties using segmented, non-segmented, and adaptively segmented 3D mouse anatomy (MOBY) are used to perform bioluminescence tomography (BLT) for two simulated internal sources. The BLT results suggest that the accuracy of reconstruction of total source power obtained without the segmentation provided by an auxiliary imaging method such as x-ray CT is comparable to that obtained when using perfect segmentation.

  6. Modelling the application of adaptive optics to wide-field microscope live imaging.

    PubMed

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

    2007-04-01

    Wide-field fluorescence microscopy is an essential tool in modern cell biology. Unfortunately the image quality of fluorescence microscopes is often significantly degraded due to aberrations that occur under normal imaging conditions. In this article, we examine the use of adaptive optics technology to dynamically correct these problems to achieve close to ideal diffraction limited performance. Simultaneously, this technology also allows ultra-rapid focusing without having to move either the stage or the objective lens. We perform optical simulations to demonstrate the degree of correction that can be achieved.

  7. Atmospheric and adaptive optics

    NASA Astrophysics Data System (ADS)

    Hickson, Paul

    2014-11-01

    Atmospheric optics is the study of optical effects induced by the atmosphere on light propagating from distant sources. Of particular concern to astronomers is atmospheric turbulence, which limits the performance of ground-based telescopes. The past two decades have seen remarkable growth in the capabilities and performance of adaptive optics (AO) systems. These opto-mechanical systems actively compensate for the blurring effect of the Earth's turbulent atmosphere. By sensing, and correcting, wavefront distortion introduced by atmospheric index-of-refraction variations, AO systems can produce images with resolution approaching the diffraction limit of the telescope at near-infrared wavelengths. This review highlights the physical processes and fundamental relations of atmospheric optics that are most relevant to astronomy, and discusses the techniques used to characterize atmospheric turbulence. The fundamentals of AO are then introduced and the many types of advanced AO systems that have been developed are described. The principles of each are outlined, and the performance and limitations are examined. Aspects of photometric and astrometric measurements of AO-corrected images are considered. The paper concludes with a discussion of some of the challenges related to current and future AO systems, particularly those that will equip the next generation of large, ground-based optical and infrared telescopes.

  8. Adaptive optics correction of a tunable fluidic lens for ophthalmic applications

    NASA Astrophysics Data System (ADS)

    Fuh, Yiin-Kuen; Lin, Ming-Xin

    2013-11-01

    Tunable fluidic lenses are utilizing curvature change via continuously adjusting injected liquid volumes to achieve variable-focusing properties. Nevertheless, the nature of curvature change and refractive index mismatch causes inherent spatial aberrations that severely degrade image quality. Here we present the experimental study of the aberrations in tunable fluidic lenses and use of adaptive optics to compensate for the wavefront errors. Adaptive optics based scheme is demonstrated for three injected liquid volumes, resulting in a substantial reduction of the wavefront errors from 0.42, 1.05, 1.49 to 0.20, 0.21, 0.23 μm, respectively, corresponding to the focal length tunability of 100-200 mm.

  9. Adaptive Optical Filtering Techniques.

    DTIC Science & Technology

    1985-05-01

    A space inte- Perhaps the most significant application of numeri- grating implementation using a parellel output wide- cal optical processors is in O... University Press, Daiumote. 19631. 177 C-5% 41% -~~ ~~~~~ % *~ .~ . e5 e r %. % *FILMED 9-85 DTIC

  10. Weighted adaptive threshold estimating method and its application to Satellite-to-Ground optical communications

    NASA Astrophysics Data System (ADS)

    Ran, Qiwen; Yang, Zhonghua; Ma, Jing; Tan, Liying; Liao, Huixi; Liu, Qingfeng

    2013-02-01

    In this paper, a weighted adaptive threshold estimating method is proposed to deal with long and deep channel fades in Satellite-to-Ground optical communications. During the channel correlation interval where there are sufficient correlations in adjacent signal samples, the correlations in its change rates are described by weighted equations in the form of Toeplitz matrix. As vital inputs to the proposed adaptive threshold estimator, the optimal values of the change rates can be obtained by solving the weighted equation systems. The effect of channel fades and aberrant samples can be mitigated by joint use of weighted equation systems and Kalman estimation. Based on the channel information data from star observation trails, simulations are made and the numerical results show that the proposed method have better anti-fade performances than the D-value adaptive threshold estimating method in both weak and strong turbulence conditions.

  11. Field of view advantage of conjugate adaptive optics in microscopy applications.

    PubMed

    Mertz, Jerome; Paudel, Hari; Bifano, Thomas G

    2015-04-10

    The imaging performance of an optical microscope can be degraded by sample-induced aberrations. A general strategy to undo the effect of these aberrations is to apply wavefront correction with a deformable mirror (DM). In most cases the DM is placed conjugate to the microscope pupil, called pupil adaptive optics (AO). When the aberrations are spatially variant an alternative configuration involves placing the DM conjugate to the main source of aberrations, called conjugate AO. We provide a theoretical and experimental comparison of both configurations for the simplified case where spatially variant aberrations are produced by a well-defined phase screen. We pay particular attention to the resulting correction field of view (FOV). Conjugate AO is found to provide a significant FOV advantage. While this result is well known in the astronomical community, our goal here is to recast it specifically for the optical microscopy community.

  12. Field of view advantage of conjugate adaptive optics in microscopy applications

    PubMed Central

    Mertz, Jerome; Paudel, Hari; Bifano, Thomas G.

    2015-01-01

    The imaging performance of an optical microscope can be degraded by sample-induced aberrations. A general strategy to undo the effect of these aberrations is to apply wavefront correction with a deformable mirror (DM). In most cases the DM is placed conjugate to the microscope pupil, called pupil adaptive optics (AO). When the aberrations are spatially variant an alternative configuration involves placing the DM conjugate to the main source of aberrations, called conjugate AO. We provide a theoretical and experimental comparison of both configurations for the simplified case where spatially variant aberrations are produced by a well defined phase screen. We pay particular attention to the resulting correction field of view (FOV). Conjugate AO is found to provide a significant FOV advantage. While this result is well known in the astronomy community, our goal here is to recast it specifically for the optical microscopy community. PMID:25967343

  13. Adaptive Optical Scanning Holography

    PubMed Central

    Tsang, P. W. M.; Poon, Ting-Chung; Liu, J.-P.

    2016-01-01

    Optical Scanning Holography (OSH) is a powerful technique that employs a single-pixel sensor and a row-by-row scanning mechanism to capture the hologram of a wide-view, three-dimensional object. However, the time required to acquire a hologram with OSH is rather lengthy. In this paper, we propose an enhanced framework, which is referred to as Adaptive OSH (AOSH), to shorten the holographic recording process. We have demonstrated that the AOSH method is capable of decreasing the acquisition time by up to an order of magnitude, while preserving the content of the hologram favorably. PMID:26916866

  14. Adaptive Optical Scanning Holography

    NASA Astrophysics Data System (ADS)

    Tsang, P. W. M.; Poon, Ting-Chung; Liu, J.-P.

    2016-02-01

    Optical Scanning Holography (OSH) is a powerful technique that employs a single-pixel sensor and a row-by-row scanning mechanism to capture the hologram of a wide-view, three-dimensional object. However, the time required to acquire a hologram with OSH is rather lengthy. In this paper, we propose an enhanced framework, which is referred to as Adaptive OSH (AOSH), to shorten the holographic recording process. We have demonstrated that the AOSH method is capable of decreasing the acquisition time by up to an order of magnitude, while preserving the content of the hologram favorably.

  15. Adaptive optics research at Lincoln Laboratory

    NASA Astrophysics Data System (ADS)

    Greenwood, Darryl P.; Primmerman, Charles A.

    A development history is presented for adaptive-optics methods of optical aberration measurement and correction in real time, which are applicable to the thermal blooming of high-energy laser beams, the compensation of a laser beam propagating from ground to space, and compensation by means of a synthetic beacon. Attention is given to schematics of the various adaptive optics system types, which cover the cases of cooperative and uncooperative targets. Representative research projects encompassed by the high-energy propagation range in West Palm Beach are the 'Everlaser' instrumented target vehicle, the OCULAR multidither system installation, and the Atmospheric Compensation Experiment Adaptive Optics System.

  16. A method for space-variant deblurring with application to adaptive optics imaging in astronomy

    NASA Astrophysics Data System (ADS)

    La Camera, A.; Schreiber, L.; Diolaiti, E.; Boccacci, P.; Bertero, M.; Bellazzini, M.; Ciliegi, P.

    2015-07-01

    Context. Images from adaptive optics systems are generally affected by significant distortions of the point spread function (PSF) across the field of view, depending on the position of natural and artificial guide stars. Image reduction techniques circumventing or mitigating these effects are important tools to take full advantage of the scientific information encoded in adaptive optics images. Aims: The aim of this paper is to propose a method for the deblurring of the astronomical image, given a set of samples of the space-variant PSF. Methods: The method is based on a partitioning of the image domain into regions of isoplanatism and on applying suitable deconvolution methods with boundary effects correction to each region. Results: The effectiveness of the boundary effects correction is proved. Moreover, the criterion for extending the disjoint sections to partially overlapping sections is validated. The method is applied to simulated images of a stellar system characterized by a spatially variable PSF. We obtain good photometric quality, and therefore good science quality, by performing aperture photometry on the deblurred images. The proposed method is implemented in IDL in the Software Package "Patch", which is available on http://www.airyproject.eu

  17. Adaptive optics for high resolution spectroscopy: a direct application with the future NIRPS spectrograph

    NASA Astrophysics Data System (ADS)

    Conod, U.; Blind, N.; Wildi, F.; Pepe, F.

    2016-07-01

    Radial velocity instruments require high spectral resolution and extreme thermo-mechanical stability, even more difficult to achieve in near-infra red (NIR) where the spectrograph has to be cooled down. For a seeing-limited spectrograph, the price of high spectral resolution is an increased instrument volume, proportional to the diameter of the primary mirror. A way to control the size, cost, and stability of radial velocity spectrographs is to reduce the beam optical etendue thanks to an Adaptive Optics (AO) system. While AO has revolutionized the field of high angular resolution and high contrast imaging during the last 20 years, it has not yet been (successfully) used as a way to control spectrographs size, especially in the field of radial velocities. In this work we present the AO module of the future NIRPS spectrograph for the ESO 3.6 m telescope, that will be feed with multi-mode fibers. We converge to an AO system using a Shack-Hartmann wavefront sensor with 14x14 subapertures, able to feed 50% of the energy into a 0.4" fiber in the range of 0.98 to 1.8 μm for M-type stars as faint as I=12.

  18. Application of adaptive optics for controlling the NIF laser performance and spot size

    SciTech Connect

    Auerbach, J.; Bliss, E.; Henesian, M.; Lawson, J.; Manes, K.; Renard, P.; Sacks, R.; Salmon, T.; Trenholme, J.; Williams, W.; Winters, S.; Zacharias, R

    1998-08-17

    The National Ignition Facility (NIF) laser will use a 192-beam multi-pass architecture capable of delivering several MJ of UV energy in temporal pulse formats varying from sub-ns square to 20 ns precisely-defined high-contrast shapes. Each beam wavefront will be subjected to effects of optics inhomogeneities, figuring errors, mounting distortions, prompt and slow thermal effects from flashlamps, driven and passive air-path turbulence, and gravity-driven deformations. A 39-actuator intra-cavity deformable mirror, controlled by data from a 77-lenslet Hartman sensor will be used to correct these wavefront aberrations and thus to assure that stringent farfield spot requirements are met. We have developed numerical models for the expected distortions, the operation of the adaptive optic system, and the anticipated effects on beam propagation, component damage, frequency conversion, and target-plane energy distribution. These models have been extensively validated against data from LLNL's Beamlet, and Amplab lasers. We review the expected beam wavefront aberrations and their potential for adverse effects on the laser performance, describe our model of the corrective system operation, and display our predictions for corrected-beam operation of the NI

  19. Adaptive optical interconnects: the ADDAPT project

    NASA Astrophysics Data System (ADS)

    Henker, Ronny; Pliva, Jan; Khafaji, Mahdi; Ellinger, Frank; Toifl, Thomas; Offrein, Bert; Cevrero, Alessandro; Oezkaya, Ilter; Seifried, Marc; Ledentsov, Nikolay; Kropp, Joerg-R.; Shchukin, Vitaly; Zoldak, Martin; Halmo, Leos; Turkiewicz, Jaroslaw; Meredith, Wyn; Eddie, Iain; Georgiades, Michael; Charalambides, Savvas; Duis, Jeroen; van Leeuwen, Pieter

    2015-09-01

    Existing optical networks are driven by dynamic user and application demands but operate statically at their maximum performance. Thus, optical links do not offer much adaptability and are not very energy-efficient. In this paper a novel approach of implementing performance and power adaptivity from system down to optical device, electrical circuit and transistor level is proposed. Depending on the actual data load, the number of activated link paths and individual device parameters like bandwidth, clock rate, modulation format and gain are adapted to enable lowering the components supply power. This enables flexible energy-efficient optical transmission links which pave the way for massive reductions of CO2 emission and operating costs in data center and high performance computing applications. Within the FP7 research project Adaptive Data and Power Aware Transceivers for Optical Communications (ADDAPT) dynamic high-speed energy-efficient transceiver subsystems are developed for short-range optical interconnects taking up new adaptive technologies and methods. The research of eight partners from industry, research and education spanning seven European countries includes the investigation of several adaptive control types and algorithms, the development of a full transceiver system, the design and fabrication of optical components and integrated circuits as well as the development of high-speed, low loss packaging solutions. This paper describes and discusses the idea of ADDAPT and provides an overview about the latest research results in this field.

  20. Application of fluidic lens technology to an adaptive holographic optical element see-through autophoropter

    NASA Astrophysics Data System (ADS)

    Chancy, Carl H.

    A device for performing an objective eye exam has been developed to automatically determine ophthalmic prescriptions. The closed loop fluidic auto-phoropter has been designed, modeled, fabricated and tested for the automatic measurement and correction of a patient's prescriptions. The adaptive phoropter is designed through the combination of a spherical-powered fluidic lens and two cylindrical fluidic lenses that are orientated 45o relative to each other. In addition, the system incorporates Shack-Hartmann wavefront sensing technology to identify the eye's wavefront error and corresponding prescription. Using the wavefront error information, the fluidic auto-phoropter nulls the eye's lower order wavefront error by applying the appropriate volumes to the fluidic lenses. The combination of the Shack-Hartmann wavefront sensor the fluidic auto-phoropter allows for the identification and control of spherical refractive error, as well as cylinder error and axis; thus, creating a truly automated refractometer and corrective system. The fluidic auto-phoropter is capable of correcting defocus error ranging from -20D to 20D and astigmatism from -10D to 10D. The transmissive see-through design allows for the observation of natural scenes through the system at varying object planes with no additional imaging optics in the patient's line of sight. In this research, two generations of the fluidic auto-phoropter are designed and tested; the first generation uses traditional glass optics for the measurement channel. The second generation of the fluidic auto-phoropter takes advantage of the progress in the development of holographic optical elements (HOEs) to replace all the traditional glass optics. The addition of the HOEs has enabled the development of a more compact, inexpensive and easily reproducible system without compromising its performance. Additionally, the fluidic lenses were tested during a National Aeronautics Space Administration (NASA) parabolic flight campaign, to

  1. Adaptive Optics Communications Performance Analysis

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    The performance improvement obtained through the use of adaptive optics for deep-space communications in the presence of atmospheric turbulence is analyzed. Using simulated focal-plane signal-intensity distributions, uncoded pulse-position modulation (PPM) bit-error probabilities are calculated assuming the use of an adaptive focal-plane detector array as well as an adaptively sized single detector. It is demonstrated that current practical adaptive optics systems can yield performance gains over an uncompensated system ranging from approximately 1 dB to 6 dB depending upon the PPM order and background radiation level.

  2. Adaptive optical label packet switching

    NASA Astrophysics Data System (ADS)

    Xiao, Shilin; Liu, Zhixin; Liang, Zheng; Zhao, Zhihui; Qu, Kefeng

    2007-11-01

    This paper introduces a kind of Adaptive Optical Label Packet Switching (AOLPS) technology. Based on Optical Packet Switching (OPS), AOLPS uses optical label to achieve self-routing, and the size of optical packet is self-adaptive. At the edge nodes, IP packets are fist classified into different first-in-fist-out memories (FIFOs) according to their priority levels and destinations, and then being encapsulated into optical packets. The traffic at each FIFO is real-time monitored, and the controller in edge node employs an optimal strategy to generate suitable sized packets for transmission. Large sized packets will be adopted when traffic is heavy, and small sized packets will be used when traffic is light. This self-adaptive switching granularity can greatly improve the network performance.

  3. Adaptive optics for peripheral vision

    NASA Astrophysics Data System (ADS)

    Rosén, R.; Lundström, L.; Unsbo, P.

    2012-07-01

    Understanding peripheral optical errors and their impact on vision is important for various applications, e.g. research on myopia development and optical correction of patients with central visual field loss. In this study, we investigated whether correction of higher order aberrations with adaptive optics (AO) improve resolution beyond what is achieved with best peripheral refractive correction. A laboratory AO system was constructed for correcting peripheral aberrations. The peripheral low contrast grating resolution acuity in the 20° nasal visual field of the right eye was evaluated for 12 subjects using three types of correction: refractive correction of sphere and cylinder, static closed loop AO correction and continuous closed loop AO correction. Running AO in continuous closed loop improved acuity compared to refractive correction for most subjects (maximum benefit 0.15 logMAR). The visual improvement from aberration correction was highly correlated with the subject's initial amount of higher order aberrations (p = 0.001, R 2 = 0.72). There was, however, no acuity improvement from static AO correction. In conclusion, correction of peripheral higher order aberrations can improve low contrast resolution, provided refractive errors are corrected and the system runs in continuous closed loop.

  4. Accuracies Of Optical Processors For Adaptive Optics

    NASA Technical Reports Server (NTRS)

    Downie, John D.; Goodman, Joseph W.

    1992-01-01

    Paper presents analysis of accuracies and requirements concerning accuracies of optical linear-algebra processors (OLAP's) in adaptive-optics imaging systems. Much faster than digital electronic processor and eliminate some residual distortion. Question whether errors introduced by analog processing of OLAP overcome advantage of greater speed. Paper addresses issue by presenting estimate of accuracy required in general OLAP that yields smaller average residual aberration of wave front than digital electronic processor computing at given speed.

  5. Adaptive optics and laser guide stars at Lick observatory

    SciTech Connect

    Brase, J.M.

    1994-11-15

    For the past several years LLNL has been developing adaptive optics systems for correction of both atmospheric turbulence effects and thermal distortions in optics for high-power lasers. Our early work focused on adaptive optics for beam control in laser isotope separation and ground-based free electron lasers. We are currently developing innovative adaptive optics and laser systems for sodium laser guide star applications at the University of California`s Lick and Keck Observeratories. This talk will describe our adaptive optics technology and some of its applications in high-resolution imaging and beam control.

  6. Robust Wiener filtering for Adaptive Optics

    SciTech Connect

    Poyneer, L A

    2004-06-17

    In many applications of optical systems, the observed field in the pupil plane has a non-uniform phase component. This deviation of the phase of the field from uniform is called a phase aberration. In imaging systems this aberration will degrade the quality of the images. In the case of a large astronomical telescope, random fluctuations in the atmosphere lead to significant distortion. These time-varying distortions can be corrected using an Adaptive Optics (AO) system, which is a real-time control system composed of optical, mechanical and computational parts. Adaptive optics is also applicable to problems in vision science, laser propagation and communication. For a high-level overview, consult this web site. For an in-depth treatment of the astronomical case, consult these books.

  7. Adaptive optics in the formation of optical beams and images

    NASA Astrophysics Data System (ADS)

    Lukin, V. P.

    2014-06-01

    In connection with the wide use of optoelectronic systems, we review the development of adaptive optics as an effective tool that allows using controllable optical elements to eliminate irregular distortions that occur as light propagates in an inhomogeneous medium. The subject matter of this rapidly developing field of science and technology is described. Of the ideas under development in recent years, many have been around for quite a long time, but it is only now, with the development of an up-to-date optoelectronic element base, that they have started being widely incorporated into science and engineering practice. We discuss the development of adaptive optics from mere ideas to their application in astronomy, high-power laser physics, and medicine. The current state of adaptive optics in stellar and solar astronomy is reviewed, and some results of its use in distortion correction systems of high-power laser systems and facilities are presented.

  8. Adaptive Optics for Industry and Medicine

    NASA Astrophysics Data System (ADS)

    Dainty, Christopher

    2008-01-01

    pt. 1. Wavefront correctors and control. Liquid crystal lenses for correction of presbyopia (Invited Paper) / Guoqiang Li and Nasser Peyghambarian. Converging and diverging liquid crystal lenses (oral paper) / Andrew X. Kirby, Philip J. W. Hands, and Gordon D. Love. Liquid lens technology for miniature imaging systems: status of the technology, performance of existing products and future trends (invited paper) / Bruno Berge. Carbon fiber reinforced polymer deformable mirrors for high energy laser applications (oral paper) / S. R. Restaino ... [et al.]. Tiny multilayer deformable mirrors (oral paper) / Tatiana Cherezova ... [et al.]. Performance analysis of piezoelectric deformable mirrors (oral paper) / Oleg Soloviev, Mikhail Loktev and Gleb Vdovin. Deformable membrane mirror with high actuator density and distributed control (oral paper) / Roger Hamelinck ... [et al.]. Characterization and closed-loop demonstration of a novel electrostatic membrane mirror using COTS membranes (oral paper) / David Dayton ... [et al.]. Electrostatic micro-deformable mirror based on polymer materials (oral paper) / Frederic Zamkotsian ... [et al.]. Recent progress in CMOS integrated MEMS A0 mirror development (oral paper) / A. Gehner ... [et al.]. Compact large-stroke piston-tip-tilt actuator and mirror (oral paper) / W. Noell ... [et al.]. MEMS deformable mirrors for high performance AO applications (oral paper) / Paul Bierden, Thomas Bifano and Steven Cornelissen. A versatile interferometric test-rig for the investigation and evaluation of ophthalmic AO systems (poster paper) / Steve Gruppetta, Jiang Jian Zhong and Luis Diaz-Santana. Woofer-tweeter adaptive optics (poster paper) / Thomas Farrell and Chris Dainty. Deformable mirrors based on transversal piezoeffect (poster paper) / Gleb Vdovin, Mikhail Loktev and Oleg Soloviev. Low-cost spatial light modulators for ophthalmic applications (poster paper) / Vincente Durán ... [et al.]. Latest MEMS DM developments and the path ahead

  9. Free Space Optical Communications Utilizing MEMS Adaptive Optics Correction

    SciTech Connect

    Thompson, C A; Kartz, M W; Flath, L M; Wilks, S C; Young, R A; Johnson, G W; Ruggiero, A J

    2002-07-09

    Free space optical communications (FSO) are beginning to provide attractive alternatives to fiber-based solutions in many situations. Currently, a handful of companies provide fiberless alternatives specifically aimed at corporate intranet and sporting event video applications. These solutions are geared toward solving the ''last mile'' connectivity issues. There exists a potential need to extend this pathlength to distances much greater than a 1 km, particularly for government and military applications. For cases of long distance optical propagation, atmospheric turbulence will ultimately limit the maximum achievable data rate. In this paper, we propose a method to improve signal quality through the use of adaptive optics. In particular, we show work in progress toward a high-speed, small footprint Adaptive Optics system for horizontal and slant path laser communications. Such a system relies heavily on recent progress in Micro-Electro-Mechanical Systems (MEMS) deformable mirrors, as well as improved communication and computational components.

  10. Coherent Digital Holographic Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Liu, Changgeng

    A new type of adaptive optics (AO) based on the principles of digital holography (DH) is proposed and developed for the use in wide-field and confocal retinal imaging. Digital holographic adaptive optics (DHAO) dispenses with the wavefront sensor and wavefront corrector of the conventional AO system. DH is an emergent imaging technology that gives direct numerical access to the phase of the optical field, thus allowing precise control and manipulation of the optical field. Incorporation of DH in an ophthalmic imaging system can lead to versatile imaging capabilities at substantially reduced complexity and cost of the instrument. A typical conventional AO system includes several critical hardware pieces: spatial light modulator, lenslet array, and a second CCD camera in addition to the camera for imaging. The proposed DHAO system replaces these hardware components with numerical processing for wavefront measurement and compensation of aberration through the principles of DH. (Abstract shortened by UMI.).

  11. Micromirror Arrays for Adaptive Optics

    SciTech Connect

    Carr, E.J.

    2000-08-07

    The long-range goal of this project is to develop the optical and mechanical design of a micromirror array for adaptive optics that will meet the following criteria: flat mirror surface ({lambda}/20), high fill factor (> 95%), large stroke (5-10 {micro}m), and pixel size {approx}-200 {micro}m. This will be accomplished by optimizing the mirror surface and actuators independently and then combining them using bonding technologies that are currently being developed.

  12. Adaptive Optics at Lawrence Livermore National Laboratory

    SciTech Connect

    Gavel, D T

    2003-03-10

    Adaptive optics enables high resolution imaging through the atmospheric by correcting for the turbulent air's aberrations to the light waves passing through it. The Lawrence Livermore National Laboratory for a number of years has been at the forefront of applying adaptive optics technology to astronomy on the world's largest astronomical telescopes, in particular at the Keck 10-meter telescope on Mauna Kea, Hawaii. The technology includes the development of high-speed electrically driven deformable mirrors, high-speed low-noise CCD sensors, and real-time wavefront reconstruction and control hardware. Adaptive optics finds applications in many other areas where light beams pass through aberrating media and must be corrected to maintain diffraction-limited performance. We describe systems and results in astronomy, medicine (vision science), and horizontal path imaging, all active programs in our group.

  13. Membrane Adaptive Optics

    DTIC Science & Technology

    2005-08-01

    F . Graff, Wave Motion in Elastic Solids, Ohio State University Press, Columbus, OH, 1975. 10. D . Malacara, ed., Optical Shop Testing, John Wiley & Sons, New York, second ed., 1992. ...Report to AFOSR mentioned earlier. -1 -0.5 0 0.5 1 Normalized Radial Coordinate ( ρ = r/a) -1 -0.5 0 0.5 1 M a x i m u m R e s i d u a l A b e...governing equations are then easily solved for the resonant frequencies, which are found to be given by the simple expression f mn = 1 2π ω

  14. Free space optical communications utilizing MEMS adaptive optics correction

    NASA Astrophysics Data System (ADS)

    Thompson, Charles A.; Kartz, Michael W.; Flath, Laurence M.; Wilks, Scott C.; Young, Richard A.; Johnson, Gary W.; Ruggiero, Anthony J.

    2002-12-01

    Free space optical communications (FSO) are beginning to provide attractive alternatives to fiber-based solutions in many situations. Currently, a handful of companies provide fiberless alternatives especially aimed at corporate intranet and sporting event video. These solutions are geared toward solving the 'last mile' connectivity issues. There exists a potential need to extend this pathlength to distances much greater than a 1 km, particularly for government and military applications. For cases of long distance optical propagation, atmospheric turbulence will ultimately limit the maximum achievable data rate. In this paper, we propose a method of improved signal quality through the use of adaptive optics. In particular, we show work in progress toward a high-speed, small footprint Adaptive Optics system for horizontal and slant path laser communications. Such a system relies heavily on recent progress in Micro-Electro-Mechanical Systems (MEMS) deformable mirrors as well as improved communication and computational components.

  15. Adaptive optical filter

    SciTech Connect

    Whittemore, Stephen Richard

    2013-09-10

    Imaging systems include a detector and a spatial light modulator (SLM) that is coupled so as to control image intensity at the detector based on predetermined detector limits. By iteratively adjusting SLM element values, image intensity at one or all detector elements or portions of an imaging detector can be controlled to be within limits. The SLM can be secured to the detector at a spacing such that the SLM is effectively at an image focal plane. In some applications, the SLM can be adjusted to impart visible or hidden watermarks to images or to reduce image intensity at one or a selected set of detector elements so as to reduce detector blooming

  16. Adaptive Optics Metrics & QC Scheme

    NASA Astrophysics Data System (ADS)

    Girard, Julien H.

    2017-09-01

    "There are many Adaptive Optics (AO) fed instruments on Paranal and more to come. To monitor their performances and assess the quality of the scientific data, we have developed a scheme and a set of tools and metrics adapted to each flavour of AO and each data product. Our decisions to repeat observations or not depends heavily on this immediate quality control "zero" (QC0). Atmospheric parameters monitoring can also help predict performances . At the end of the chain, the user must be able to find the data that correspond to his/her needs. In Particular, we address the special case of SPHERE."

  17. Adaptive optics optical coherence tomography in glaucoma.

    PubMed

    Dong, Zachary M; Wollstein, Gadi; Wang, Bo; Schuman, Joel S

    2017-03-01

    Since the introduction of commercial optical coherence tomography (OCT) systems, the ophthalmic imaging modality has rapidly expanded and it has since changed the paradigm of visualization of the retina and revolutionized the management and diagnosis of neuro-retinal diseases, including glaucoma. OCT remains a dynamic and evolving imaging modality, growing from time-domain OCT to the improved spectral-domain OCT, adapting novel image analysis and processing methods, and onto the newer swept-source OCT and the implementation of adaptive optics (AO) into OCT. The incorporation of AO into ophthalmic imaging modalities has enhanced OCT by improving image resolution and quality, particularly in the posterior segment of the eye. Although OCT previously captured in-vivo cross-sectional images with unparalleled high resolution in the axial direction, monochromatic aberrations of the eye limit transverse or lateral resolution to about 15-20 μm and reduce overall image quality. In pairing AO technology with OCT, it is now possible to obtain diffraction-limited resolution images of the optic nerve head and retina in three-dimensions, increasing resolution down to a theoretical 3 μm(3). It is now possible to visualize discrete structures within the posterior eye, such as photoreceptors, retinal nerve fiber layer bundles, the lamina cribrosa, and other structures relevant to glaucoma. Despite its limitations and barriers to widespread commercialization, the expanding role of AO in OCT is propelling this technology into clinical trials and onto becoming an invaluable modality in the clinician's arsenal.

  18. Analytical expression of long-exposure adaptive-optics-corrected coronagraphic image. First application to exoplanet detection.

    PubMed

    Sauvage, J-F; Mugnier, L M; Rousset, G; Fusco, T

    2010-11-01

    In this paper we derive an analytical model of a long-exposure star image for an adaptive-optics(AO)-corrected coronagraphic imaging system. This expression accounts for static aberrations upstream and downstream of the coronagraphic mask as well as turbulence residuals. It is based on the perfect coronagraph model. The analytical model is validated by means of simulations using the design and parameters of the SPHERE instrument. The analytical model is also compared to a simulated four-quadrant phase-mask coronagraph. Then, its sensitivity to a miscalibration of structure function and upstream static aberrations is studied, and the impact on exoplanet detectability is quantified. Last, a first inversion method is presented for a simulation case using a single monochromatic image with no reference. The obtained result shows a planet detectability increase by two orders of magnitude with respect to the raw image. This analytical model presents numerous potential applications in coronographic imaging, such as exoplanet direct detection, and circumstellar disk observation.

  19. Optical Property Analyses of Plant Cells for Adaptive Optics Microscopy

    NASA Astrophysics Data System (ADS)

    Tamada, Yosuke; Murata, Takashi; Hattori, Masayuki; Oya, Shin; Hayano, Yutaka; Kamei, Yasuhiro; Hasebe, Mitsuyasu

    2014-04-01

    In astronomy, adaptive optics (AO) can be used to cancel aberrations caused by atmospheric turbulence and to perform diffraction-limited observation of astronomical objects from the ground. AO can also be applied to microscopy, to cancel aberrations caused by cellular structures and to perform high-resolution live imaging. As a step toward the application of AO to microscopy, here we analyzed the optical properties of plant cells. We used leaves of the moss Physcomitrella patens, which have a single layer of cells and are thus suitable for optical analysis. Observation of the cells with bright field and phase contrast microscopy, and image degradation analysis using fluorescent beads demonstrated that chloroplasts provide the main source of optical degradations. Unexpectedly, the cell wall, which was thought to be a major obstacle, has only a minor effect. Such information provides the basis for the application of AO to microscopy for the observation of plant cells.

  20. Extreme Adaptive Optics Planet Imager

    NASA Astrophysics Data System (ADS)

    Macintosh, B.; Graham, J. R.; Ghez, A.; Kalas, P.; Lloyd, J.; Makidon, R.; Olivier, S.; Patience, J.; Perrin, M.; Poyneer, L.; Severson, S.; Sheinis, A.; Sivaramakrishnan, A.; Troy, M.; Wallace, J.; Wilhelmsen, J.

    2002-12-01

    Direct detection of photons emitted or reflected by extrasolar planets is the next major step in extrasolar planet studies. Current adaptive optics (AO) systems, with <300 subapertures and Strehl ratio 0.4-0.7, can achieve contrast levels of 106 at 2" separations; this is sufficient to see very young planets in wide orbits but insufficient to detect solar systems more like our own. Contrast levels of 107 - 108 in the near-IR are needed to probe a significant part of the extrasolar planet phase space. The NSF Center for Adaptive Optics is carrying out a design study for a dedicated ultra-high-contrast "Extreme" adaptive optics system for an 8-10m telescope. With 3000 controlled subapertures it should achieve Strehl ratios > 0.9 in the near-IR. Using a spatially filtered wavefront sensor, the system will be optimized to control scattered light over a large radius and suppress artifacts caused static errors. We predict that it will achieve contrast levels of 107-108 around a large sample of stars (R<7-10), sufficient to detect Jupiter-like planets through their near-IR emission over a wide range of ages and masses. The system will be capable of a variety of high-contrast science including studying circumstellar dust disks at densities a factor of 10-100 lower than currently feasible and a systematic inventory of other solar systems on 10-100 AU scale. This work was supported by the NSF Science and Technology Center for Adaptive Optics, managed by UC Santa Cruz under AST-9876783. Portions of this work was performed under the auspices of the U.S. Department of Energy, under contract No. W-7405-Eng-48.

  1. Adaptive optics with a magnetic deformable mirror: applications in the human eye

    NASA Astrophysics Data System (ADS)

    Fernandez, Enrique J.; Vabre, Laurent; Hermann, Boris; Unterhuber, Angelika; Povazay, Boris; Drexler, Wolfgang

    2006-10-01

    A novel deformable mirror using 52 independent magnetic actuators (MIRAO 52, Imagine Eyes) is presented and characterized for ophthalmic applications. The capabilities of the device to reproduce different surfaces, in particular Zernike polynomials up to the fifth order, are investigated in detail. The study of the influence functions of the deformable mirror reveals a significant linear response with the applied voltage. The correcting device also presents a high fidelity in the generation of surfaces. The ranges of production of Zernike polynomials fully cover those typically found in the human eye, even for the cases of highly aberrated eyes. Data from keratoconic eyes are confronted with the obtained ranges, showing that the deformable mirror is able to compensate for these strong aberrations. Ocular aberration correction with polychromatic light, using a near Gaussian spectrum of 130 nm full width at half maximum centered at 800 nm, in five subjects is accomplished by simultaneously using the deformable mirror and an achromatizing lens, in order to compensate for the monochromatic and chromatic aberrations, respectively. Results from living eyes, including one exhibiting 4.66 D of myopia and a near pathologic cornea with notable high order aberrations, show a practically perfect aberration correction. Benefits and applications of simultaneous monochromatic and chromatic aberration correction are finally discussed in the context of retinal imaging and vision.

  2. Driver Code for Adaptive Optics

    NASA Technical Reports Server (NTRS)

    Rao, Shanti

    2007-01-01

    A special-purpose computer code for a deformable-mirror adaptive-optics control system transmits pixel-registered control from (1) a personal computer running software that generates the control data to (2) a circuit board with 128 digital-to-analog converters (DACs) that generate voltages to drive the deformable-mirror actuators. This program reads control-voltage codes from a text file, then sends them, via the computer s parallel port, to a circuit board with four AD5535 (or equivalent) chips. Whereas a similar prior computer program was capable of transmitting data to only one chip at a time, this program can send data to four chips simultaneously. This program is in the form of C-language code that can be compiled and linked into an adaptive-optics software system. The program as supplied includes source code for integration into the adaptive-optics software, documentation, and a component that provides a demonstration of loading DAC codes from a text file. On a standard Windows desktop computer, the software can update 128 channels in 10 ms. On Real-Time Linux with a digital I/O card, the software can update 1024 channels (8 boards in parallel) every 8 ms.

  3. Sparse-aperture adaptive optics

    NASA Astrophysics Data System (ADS)

    Tuthill, Peter; Lloyd, James; Ireland, Michael; Martinache, Frantz; Monnier, John; Woodruff, Henry; ten Brummelaar, Theo; Turner, Nils; Townes, Charles

    2006-06-01

    Aperture masking interferometry and Adaptive Optics (AO) are two of the competing technologies attempting to recover diffraction-limited performance from ground-based telescopes. However, there are good arguments that these techniques should be viewed as complementary, not competitive. Masking has been shown to deliver superior PSF calibration, rejection of atmospheric noise and robust recovery of phase information through the use of closure phases. However, this comes at the penalty of loss of flux at the mask, restricting the technique to bright targets. Adaptive optics, on the other hand, can reach a fainter class of objects but suffers from the difficulty of calibration of the PSF which can vary with observational parameters such as seeing, airmass and source brightness. Here we present results from a fusion of these two techniques: placing an aperture mask downstream of an AO system. The precision characterization of the PSF enabled by sparse-aperture interferometry can now be applied to deconvolution of AO images, recovering structure from the traditionally-difficult regime within the core of the AO-corrected transfer function. Results of this program from the Palomar and Keck adaptive optical systems are presented.

  4. Exploiting Adaptive Optics with Deformable Secondary Mirrors

    DTIC Science & Technology

    2007-03-08

    progress in tomographic wavefront sensing and altitude conjugated adaptive correction, and is a critical step forward for adaptive optics for future large...geostationary satellites, captured at the 6.5 m MMT telescope, using the deformable secondary adaptive optics system....new technology to the unique development of deformable secondary mirrors pioneered at the University of Arizona’s Center for Astronomical Adaptive

  5. A tunable electrochromic fabry-perot filter for adaptive optics applications.

    SciTech Connect

    Blaich, Jonathan David; Kammler, Daniel R.; Ambrosini, Andrea; Sweatt, William C.; Verley, Jason C.; Heller, Edwin J.; Yelton, William Graham

    2006-10-01

    The potential for electrochromic (EC) materials to be incorporated into a Fabry-Perot (FP) filter to allow modest amounts of tuning was evaluated by both experimental methods and modeling. A combination of chemical vapor deposition (CVD), physical vapor deposition (PVD), and electrochemical methods was used to produce an ECFP film stack consisting of an EC WO{sub 3}/Ta{sub 2}O{sub 5}/NiO{sub x}H{sub y} film stack (with indium-tin-oxide electrodes) sandwiched between two Si{sub 3}N{sub 4}/SiO{sub 2} dielectric reflector stacks. A process to produce a NiO{sub x}H{sub y} charge storage layer that freed the EC stack from dependence on atmospheric humidity and allowed construction of this complex EC-FP stack was developed. The refractive index (n) and extinction coefficient (k) for each layer in the EC-FP film stack was measured between 300 and 1700 nm. A prototype EC-FP filter was produced that had a transmission at 500 nm of 36%, and a FWHM of 10 nm. A general modeling approach that takes into account the desired pass band location, pass band width, required transmission and EC optical constants in order to estimate the maximum tuning from an EC-FP filter was developed. Modeling shows that minor thickness changes in the prototype stack developed in this project should yield a filter with a transmission at 600 nm of 33% and a FWHM of 9.6 nm, which could be tuned to 598 nm with a FWHM of 12.1 nm and a transmission of 16%. Additional modeling shows that if the EC WO{sub 3} absorption centers were optimized, then a shift from 600 nm to 598 nm could be made with a FWHM of 11.3 nm and a transmission of 20%. If (at 600 nm) the FWHM is decreased to 1 nm and transmission maintained at a reasonable level (e.g. 30%), only fractions of a nm of tuning would be possible with the film stack considered in this study. These tradeoffs may improve at other wavelengths or with EC materials different than those considered here. Finally, based on our limited investigation and material set

  6. Acousto-Optic Adaptive Processing (AOAP).

    DTIC Science & Technology

    1983-12-01

    I ~.sls Phe Report December 1963 •- ACOUSTO - OPTIC ADAPTIVE <PROCESSING (AOAP) General Electric Company W. A. Penn, D. R. Morgan, A. Aridgides and M. L...numnber) Optical signal processing Acousto - optical modulators Adaptive signal processing - Adaptive sidelobe cancellation 20. ABSTRACT (Contnue an...required operations of multiplication and time delay are provided by acousto - optical (AO) delay lines. The required time integraticO is provided by

  7. New Adaptive Optics Technique Demonstrated

    NASA Astrophysics Data System (ADS)

    2007-03-01

    First ever Multi-Conjugate Adaptive Optics at the VLT Achieves First Light On the evening of 25 March 2007, the Multi-Conjugate Adaptive Optics Demonstrator (MAD) achieved First Light at the Visitor Focus of Melipal, the third Unit Telescope of the Very Large Telescope (VLT). MAD allowed the scientists to obtain images corrected for the blurring effect of atmospheric turbulence over the full 2x2 arcminute field of view. This world premiere shows the promises of a crucial technology for Extremely Large Telescopes. ESO PR Photo 19a/07 ESO PR Photo 19a/07 The MCAO Demonstrator Telescopes on the ground suffer from the blurring effect induced by atmospheric turbulence. This turbulence causes the stars to twinkle in a way which delights the poets but frustrates the astronomers, since it blurs the fine details of the images. However, with Adaptive Optics (AO) techniques, this major drawback can be overcome so that the telescope produces images that are as sharp as theoretically possible, i.e., approaching space conditions. Adaptive Optics systems work by means of a computer-controlled deformable mirror (DM) that counteracts the image distortion induced by atmospheric turbulence. It is based on real-time optical corrections computed from image data obtained by a 'wavefront sensor' (a special camera) at very high speed, many hundreds of times each second. The concept is not new. Already in 1989, the first Adaptive Optics system ever built for Astronomy (aptly named "COME-ON") was installed on the 3.6-m telescope at the ESO La Silla Observatory, as the early fruit of a highly successful continuing collaboration between ESO and French research institutes (ONERA and Observatoire de Paris). Ten years ago, ESO initiated an Adaptive Optics program to serve the needs for its frontline VLT project. Today, the Paranal Observatory is without any doubt one of the most advanced of its kind with respect to AO with no less than 7 systems currently installed (NACO, SINFONI, CRIRES and

  8. Vision science and adaptive optics, the state of the field.

    PubMed

    Marcos, Susana; Werner, John S; Burns, Stephen A; Merigan, William H; Artal, Pablo; Atchison, David A; Hampson, Karen M; Legras, Richard; Lundstrom, Linda; Yoon, Geungyoung; Carroll, Joseph; Choi, Stacey S; Doble, Nathan; Dubis, Adam M; Dubra, Alfredo; Elsner, Ann; Jonnal, Ravi; Miller, Donald T; Paques, Michel; Smithson, Hannah E; Young, Laura K; Zhang, Yuhua; Campbell, Melanie; Hunter, Jennifer; Metha, Andrew; Palczewska, Grazyna; Schallek, Jesse; Sincich, Lawrence C

    2017-03-01

    Adaptive optics is a relatively new field, yet it is spreading rapidly and allows new questions to be asked about how the visual system is organized. The editors of this feature issue have posed a series of question to scientists involved in using adaptive optics in vision science. The questions are focused on three main areas. In the first we investigate the use of adaptive optics for psychophysical measurements of visual system function and for improving the optics of the eye. In the second, we look at the applications and impact of adaptive optics on retinal imaging and its promise for basic and applied research. In the third, we explore how adaptive optics is being used to improve our understanding of the neurophysiology of the visual system. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Development of large aperture composite adaptive optics

    NASA Astrophysics Data System (ADS)

    Kmetik, Viliam; Vitovec, Bohumil; Jiran, Lukas; Nemcova, Sarka; Zicha, Josef; Inneman, Adolf; Mikulickova, Lenka; Pavlica, Richard

    2015-01-01

    Large aperture composite adaptive optics for laser applications is investigated in cooperation of Institute of Plasma Physic, Department of Instrumentation and Control Engineering FME CTU and 5M Ltd. We are exploring opportunity of a large-size high-power-laser deformable-mirror production using a lightweight bimorph actuated structure with a composite core. In order to produce a sufficiently large operational free aperture we are developing new technologies for production of flexible core, bimorph actuator and deformable mirror reflector. Full simulation of a deformable-mirrors structure was prepared and validated by complex testing. A deformable mirror actuation and a response of a complicated structure are investigated for an accurate control of the adaptive optics. An original adaptive optics control system and a bimorph deformable mirror driver were developed. Tests of material samples, components and sub-assemblies were completed. A subscale 120 mm bimorph deformable mirror prototype was designed, fabricated and thoroughly tested. A large-size 300 mm composite-core bimorph deformable mirror was simulated and optimized, fabrication of a prototype is carried on. A measurement and testing facility is modified to accommodate large sizes optics.

  10. Test Target for Adaptive Optics.

    DTIC Science & Technology

    adaptive optics comprising, in the preferred embodiment, a plurality of nine adjacent, stacked, and aligned rows of a multiplicity of alternate opaque sections and transparent sections in a repeating bar pattern, with all sections being positioned on a flat transparent medium (such as film or glass), and with each opaque section being an opaque bar and with each transparent section being a transparent bar. Each row has a different spatial frequency than any other of the nine rows, with the spatial frequency of any one row being of a different multiple of the row having the

  11. [Wavefront analysis and adaptive optics].

    PubMed

    Stevens, J D; Sekundo, W

    2003-08-01

    In this paper we attempt to provide an overview of the principles of wavefront measurement. We also discuss the operational principles of different systems currently present on the market including their advantages and disadvantages. Moreover, we speculate on current and possible future implications of this new technology in the laser refractive surgery. Adaptive optics are explained in the context of "customized ablation" and preoperative verification of the desired results. Finally, the first international clinical results of wavefront guided excimer laser surgery are reviewed and critically commented.

  12. Adaptive optics without guide stars (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Mertz, Jerome; Li, Jiang; Beaulieu, Devin; Paudel, Hari P.; Barankov, Roman; Bifano, Thomas G.

    2016-03-01

    Adaptive optics is a strategy to compensate for sample-induced aberrations in microscopy applications. Generally, it requires the presence of "guide stars" in the sample to serve as localized reference targets. We describe an implementation of conjugate adaptive optics that is amenable to widefield (i.e. non-scanning) microscopy, and can provide aberration corrections over potentially large fields of view without the use of guide stars. A unique feature of our implementation is that it is based on wavefront sensing with a single-shot partitioned-aperture sensor that provides large dynamic range compatible with extended samples. Combined information provided by this sensor and the imaging camera enable robust image de-blurring based on a rapid estimation of sample and aberrations obtained by closed-loop feedback. We present the theoretical principle of our technique and experimental demonstrations using both trans-illumination and fluorescence microscopes. Finally, we apply our technique to mouse brain imaging.

  13. Adaptive Optics For The ESO-VLT

    NASA Astrophysics Data System (ADS)

    Merkle, Fritz

    1990-07-01

    This paper discusses the principles of adaptive optics, its performance, and its requirements for applications in astronomy to overcome limitations due to atmospheric turbulence. Guidelines for the implementation of these devices in telescopes are given in particular for the Very Large Telescope (VLT) of the European Southern Observatory. It is intended to equip each (me of the four 8-meter telescopes of the ESO- VLT, which are arranged in a linear array with an independent adaptive optical system. These systems will serve the individual and the combined Coude foci. In a first approach diffraction limited imaging for 3.5μm and longer is envisaged resulting a resolution of a few hundredths of an arcseconds. Currently, a small scale prototype adaptive system is under development. It is equipped with a 19 piezoelectric actuator deformable mirror, a Shack-Hartmann type wavefront sensor, and a dedicated wavefront computer for closing the feedback loop. This system is based on a polychromatic approach, i.e. it senses the wavefront in the visible but the adaptive correction loop works for the infrared wavelength range from .1 to 5 μm. The experience with this system will be used for the development of the final VLT systems, requiring a minimum of 150 to 200 subapertures. To solve the reference source problems experiments to generate artificial reference stars by scattering a laser pulse in the upper atmosphere are in preparation. Major developments are still necessary to solve the data processing problems which are associated with large numbers of subapertures and high correction bandwidth, especially if one plans later to extend the wavelength range towards the visible. In the VLT project adaptive optics is of particular importance for its synthetic aperture observation mode as a long baseline interferometer with resolutions in the range of a few milliarseconds on the sky. In this application a complete phasing of the telescope array is required in order to have the

  14. Fluorescence digital holographic adaptive optics microscopy

    NASA Astrophysics Data System (ADS)

    Man, Tianlong; Wan, Yuhong; Wang, Dayong

    2015-05-01

    Fluorescence microscopy is widely used in various of practical applications now. High resolution optical sectional microscopic imaging utilized by confocal two- or multi-photon fluorescence microscopy has became an essential tool in biological researches. However, optical aberrations introduced by nonhomogeneity refractive index of tissues degraded the resolution and brightness of the images. Here we present the implementation of self-interference digital holographic adaptive optics in fluorescence microscopy. Wavefront sensing and correction is achieved by holographic recording and numerical processing approach, dispenses with Shack-Hartmann sensor and deformable mirror-based complicated system. The operation speed of the system is enhanced using off-axis Fourier triangular holography. Both the influence of the size and axial position of the guide star on the quality of the corrected images are investigated.

  15. The ERIS adaptive optics system

    NASA Astrophysics Data System (ADS)

    Marchetti, Enrico; Fedrigo, Enrico; Le Louarn, Miska; Madec, Pierre-Yves; Soenke, Christian; Brast, Roland; Conzelmann, Ralf; Delabre, Bernard; Duchateau, Michel; Frank, Christoph; Klein, Barbara; Amico, Paola; Hubin, Norbert; Esposito, Simone; Antichi, Jacopo; Carbonaro, Luca; Puglisi, Alfio; Quirós-Pacheco, Fernando; Riccardi, Armando; Xompero, Marco

    2014-07-01

    The Enhanced Resolution Imager and Spectrograph (ERIS) is the new Adaptive Optics based instrument for ESO's VLT aiming at replacing NACO and SINFONI to form a single compact facility with AO fed imaging and integral field unit spectroscopic scientific channels. ERIS completes the instrument suite at the VLT adaptive telescope. In particular it is equipped with a versatile AO system that delivers up to 95% Strehl correction in K band for science observations up to 5 micron It comprises high order NGS and LGS correction enabling the observation from exoplanets to distant galaxies with a large sky coverage thanks to the coupling of the LGS WFS with the high sensitivity of its visible WFS and the capability to observe in dust embedded environment thanks to its IR low order WFS. ERIS will be installed at the Cassegrain focus of the VLT unit hosting the Adaptive Optics Facility (AOF). The wavefront correction is provided by the AOF deformable secondary mirror while the Laser Guide Star is provided by one of the four launch units of the 4 Laser Guide Star Facility for the AOF. The overall layout of the ERIS AO system is extremely compact and highly optimized: the SPIFFI spectrograph is fed directly by the Cassegrain focus and both the NIX's (IR imager) and SPIFFI's entrance windows work as visible/infrared dichroics. In this paper we describe the concept of the ERIS AO system in detail, starting from the requirements and going through the estimated performance, the opto-mechanical design and the Real-Time Computer design.

  16. ERIS adaptive optics system design

    NASA Astrophysics Data System (ADS)

    Marchetti, Enrico; Le Louarn, Miska; Soenke, Christian; Fedrigo, Enrico; Madec, Pierre-Yves; Hubin, Norbert

    2012-07-01

    The Enhanced Resolution Imager and Spectrograph (ERIS) is the next-generation instrument planned for the Very Large Telescope (VLT) and the Adaptive Optics facility (AOF). It is an AO assisted instrument that will make use of the Deformable Secondary Mirror and the new Laser Guide Star Facility (4LGSF), and it is planned for the Cassegrain focus of the telescope UT4. The project is currently in its Phase A awaiting for approval to continue to the next phases. The Adaptive Optics system of ERIS will include two wavefront sensors (WFS) to maximize the coverage of the proposed sciences cases. The first is a high order 40x40 Pyramid WFS (PWFS) for on axis Natural Guide Star (NGS) observations. The second is a high order 40x40 Shack-Hartmann WFS for single Laser Guide Stars (LGS) observations. The PWFS, with appropriate sub-aperture binning, will serve also as low order NGS WFS in support to the LGS mode with a field of view patrolling capability of 2 arcmin diameter. Both WFSs will be equipped with the very low read-out noise CCD220 based camera developed for the AOF. The real-time reconstruction and control is provided by a SPARTA real-time platform adapted to support both WFS modes. In this paper we will present the ERIS AO system in all its main aspects: opto-mechanical design, real-time computer design, control and calibrations strategy. Particular emphasis will be given to the system performance obtained via dedicated numerical simulations.

  17. Optimizing the sampling density of a wave-front sensor in adaptive optics systems: application to scanning laser ophthalmoscopy

    NASA Astrophysics Data System (ADS)

    Laslandes, Marie; Salas, Matthias; Hitzenberger, Christoph K.; Pircher, Michael

    2017-02-01

    We present the optimization of an adaptive optics loop for retinal imaging. Generally, the wave-front is overdetermined compared to the number of corrector elements. The sampling of the sensor can be reduced while maintaining an efficient correction, leading to higher sensitivity, faster correction and larger dynamic range. An analytical model was developed to characterize the link between number of actuators, number of micro-lenses and correction performance. The optimized correction loop was introduced into a scanning laser ophthalmoscope. In vivo images of foveal photoreceptors were recorded and the obtained image quality is equivalent to the state of the art in retinal AO-imaging.

  18. Robotic visible-light laser adaptive optics

    NASA Astrophysics Data System (ADS)

    Baranec, Christoph; Riddle, Reed; Law, Nicholas; Ramaprakash, A. N.; Tendulkar, Shriharsh; Bui, Khanh; Burse, Mahesh; Chordia, Pravin; Das, Hillol; Dekany, Richard; Kulkarni, Shrinivas; Punnadi, Sujit

    2013-12-01

    Robo-AO is the first autonomous laser adaptive optics system and science instrument operating on sky. With minimal human oversight, the system robotically executes large scale surveys, monitors long-term astrophysical dynamics and characterizes newly discovered transients, all at the visible diffraction limit. The adaptive optics setup time, from the end of the telescope slew to the beginning of an observation, is a mere ~50-60 s, enabling over 200 observations per night. The first of many envisioned systems has finished 58 nights of science observing at the Palomar Observatory 60-inch (1.5 m) telescope, with over 6,400 robotic observations executed thus far. The system will be augmented in late 2013 with a low-noise wide field infrared camera, which doubles as a tip-tilt sensor, to widen the spectral bandwidth of observations and increase available sky coverage while also enabling deeper visible imaging using adaptive-optics sharpened infrared tip-tilt guide sources. Techniques applicable to larger telescope systems will also be tested: the infrared camera will be used to demonstrate advanced multiple region-of-interest tip-tilt guiding methods, and a visitor instrument port will be used for evaluation of other instrumentation, e.g. single-mode and photonic fibers to feed compact spectrographs.

  19. CAOS: Code for Adaptive Optics Systems

    NASA Astrophysics Data System (ADS)

    Carbillet, M.; Verinaud, C.; Femenia, B.; Riccardi, A.; Fini, L.

    2011-06-01

    The CAOS "system" (where CAOS stands for Code for Adaptive Optics Systems) is properly said a Problem Solving Environment (PSE). It is essentially composed of a graphical programming interface (the CAOS Application Builder) which can load different packages (set of modules). Current publicly distributed packages are the Software Package CAOS (the original adaptive optics package), the Software Package AIRY (an image-reconstruction-oriented package - AIRY stands for Astronomical Image Restoration with interferometrY), the Software Package PAOLAC (a simple CAOS interface for the analytic IDL code PAOLA developed by Laurent Jolissaint - PAOLAC stands for PAOLA within Caos), and a couple of private packages (not publicly distributed but restricted to the corresponding consortia): SPHERE (especially developed for the VLT planet finder SPHERE), and AIRY-LN (a specialized version of AIRY for the LBT instrument LINC-NIRVANA). Another package is also being developed: MAOS (that stands for Multiconjugate Adaptive Optics Simulations), developed for multi-reference multiconjugate AO studies purpose but still in a beta-version form.

  20. [Examination of visual performance by adaptive optics].

    PubMed

    Weigel, D; Jungnickel, H; Babovsky, H; Kiessling, A; Kowarschik, R

    2013-12-01

    The dependence of visual quality on higher order aberrations (HOA) is highly important for refractive surgery (LASIK) as well as for the correction by vision aids. The use of the adaptive optics (AO) enables the measurement and manipulation of conventional lower order aberrations (defocus, astigmatism) and for HOAs as well. In this work, an Adaptive Optics Visual Simulator is presented that enables one to correct wave-front deformations up to the sixth order of Zernike polynomials, as well as to induce specific aberrations. The subjects observe a TFT monitor, so that a subjective rating of the visual impression is possible, as well as objective measurements. Possible applications of such an adaptive optics visual simulator are demonstrated by means of several studies in this survey paper. The main challenge was to investigate the influence of HOAs on the subjective visual impression. Thereby, the following questions have been examined among others: Does the correction of the HOAs lead to an improved visual impression? Are there ways to check the effect of HOAs, what are the effects of single HOAs on the subjective visual impression and what just-noticeable levels do they have? Three studies are presented investigating the impact of HOAs on visus, contrast sensitivity and on vision with glare as well as objective stimulus thresholds of selected HOAs. For example, by using a staircase-procedure it was possible to determine that the objective stimulus threshold for coma has a significantly lower value than the thresholds for astigmatism or trefoil. Adaptive optics enables the investigation of effects of HOAs on subjective and objective visual impression. In future, this may result in individualised corrections of refractive errors, which will improve the patient's quality of life. Georg Thieme Verlag KG Stuttgart · New York.

  1. Geometric view of adaptive optics control

    NASA Astrophysics Data System (ADS)

    Wiberg, Donald M.; Max, Claire E.; Gavel, Donald T.

    2005-05-01

    The objective of an astronomical adaptive optics control system is to minimize the residual wave-front error remaining on the science-object wave fronts after being compensated for atmospheric turbulence and telescope aberrations. Minimizing the mean square wave-front residual maximizes the Strehl ratio and the encircled energy in pointlike images and maximizes the contrast and resolution of extended images. We prove the separation principle of optimal control for application to adaptive optics so as to minimize the mean square wave-front residual. This shows that the residual wave-front error attributable to the control system can be decomposed into three independent terms that can be treated separately in design. The first term depends on the geometry of the wave-front sensor(s), the second term depends on the geometry of the deformable mirror(s), and the third term is a stochastic term that depends on the signal-to-noise ratio. The geometric view comes from understanding that the underlying quantity of interest, the wave-front phase surface, is really an infinite-dimensional vector within a Hilbert space and that this vector space is projected into subspaces we can control and measure by the deformable mirrors and wave-front sensors, respectively. When the control and estimation algorithms are optimal, the residual wave front is in a subspace that is the union of subspaces orthogonal to both of these projections. The method is general in that it applies both to conventional (on-axis, ground-layer conjugate) adaptive optics architectures and to more complicated multi-guide-star- and multiconjugate-layer architectures envisaged for future giant telescopes. We illustrate the approach by using a simple example that has been worked out previously [J. Opt. Soc. Am. A73, 1171 (1983)] for a single-conjugate, static atmosphere case and follow up with a discussion of how it is extendable to general adaptive optics architectures.

  2. Keck adaptive optics: control subsystem

    SciTech Connect

    Brase, J.M.; An, J.; Avicola, K.

    1996-03-08

    Adaptive optics on the Keck 10 meter telescope will provide an unprecedented level of capability in high resolution ground based astronomical imaging. The system is designed to provide near diffraction limited imaging performance with Strehl {gt} 0.3 n median Keck seeing of r0 = 25 cm, T =10 msec at 500 nm wavelength. The system will be equipped with a 20 watt sodium laser guide star to provide nearly full sky coverage. The wavefront control subsystem is responsible for wavefront sensing and the control of the tip-tilt and deformable mirrors which actively correct atmospheric turbulence. The spatial sampling interval for the wavefront sensor and deformable mirror is de=0.56 m which gives us 349 actuators and 244 subapertures. This paper summarizes the wavefront control system and discusses particular issues in designing a wavefront controller for the Keck telescope.

  3. Electron density measurements for plasma adaptive optics

    NASA Astrophysics Data System (ADS)

    Neiswander, Brian W.

    Over the past 40 years, there has been growing interest in both laser communications and directed energy weapons that operate from moving aircraft. As a laser beam propagates from an aircraft in flight, it passes through boundary layers, turbulence, and shear layers in the near-region of the aircraft. These fluid instabilities cause strong density gradients which adversely affect the transmission of laser energy to a target. Adaptive optics provides corrective measures for this problem but current technology cannot respond quickly enough to be useful for high speed flight conditions. This research investigated the use of plasma as a medium for adaptive optics for aero-optics applications. When a laser beam passes through plasma, its phase is shifted proportionally to the electron density and gas heating within the plasma. As a result, plasma can be utilized as a dynamically controllable optical medium. Experiments were carried out using a cylindrical dielectric barrier discharge plasma chamber which generated a sub-atmospheric pressure, low-temperature plasma. An electrostatic model of this design was developed and revealed an important design constraint relating to the geometry of the chamber. Optical diagnostic techniques were used to characterize the plasma discharge. Single-wavelength interferometric experiments were performed and demonstrated up to 1.5 microns of optical path difference (OPD) in a 633 nm laser beam. Dual-wavelength interferometry was used to obtain time-resolved profiles of the plasma electron density and gas heating inside the plasma chamber. Furthermore, a new multi-wavelength infrared diagnostic technique was developed and proof-of-concept simulations were conducted to demonstrate the system's capabilities.

  4. Task performance in astronomical adaptive optics

    NASA Astrophysics Data System (ADS)

    Barrett, Harrison H.; Myers, Kyle J.; Devaney, Nicholas; Dainty, J. C.; Caucci, Luca

    2006-06-01

    In objective or task-based assessment of image quality, figures of merit are defined by the performance of some specific observer on some task of scientific interest. This methodology is well established in medical imaging but is just beginning to be applied in astronomy. In this paper we survey the theory needed to understand the performance of ideal or ideal-linear (Hotelling) observers on detection tasks with adaptive-optical data. The theory is illustrated by discussing its application to detection of exoplanets from a sequence of short-exposure images.

  5. Large aperture adaptive optics for intense lasers

    NASA Astrophysics Data System (ADS)

    Deneuville, François; Ropert, Laurent; Sauvageot, Paul; Theis, Sébastien

    2015-05-01

    ISP SYSTEM has developed a range of large aperture electro-mechanical deformable mirrors (DM) suitable for ultra short pulsed intense lasers. The design of the MD-AME deformable mirror is based on force application on numerous locations thanks to electromechanical actuators driven by stepper motors. DM design and assembly method have been adapted to large aperture beams and the performances were evaluated on a first application for a beam with a diameter of 250mm at 45° angle of incidence. A Strehl ratio above 0.9 was reached for this application. Simulations were correlated with measurements on optical bench and the design has been validated by calculation for very large aperture (up to Ø550mm). Optical aberrations up to Zernike order 5 can be corrected with a very low residual error as for actual MD-AME mirror. Amplitude can reach up to several hundreds of μm for low order corrections. Hysteresis is lower than 0.1% and linearity better than 99%. Contrary to piezo-electric actuators, the μ-AME actuators avoid print-through effects and they permit to keep the mirror shape stable even unpowered, providing a high resistance to electro-magnetic pulses. The MD-AME mirrors can be adapted to circular, square or elliptical beams and they are compatible with all dielectric or metallic coatings.

  6. High-order adaptive optics requirements for direct detection of extrasolar planets: Application to the SPHERE instrument.

    PubMed

    Fusco, T; Rousset, G; Sauvage, J-F; Petit, C; Beuzit, J-L; Dohlen, K; Mouillet, D; Charton, J; Nicolle, M; Kasper, M; Baudoz, P; Puget, P

    2006-08-21

    The detection of extrasolar planets implies an extremely high-contrast, long-exposure imaging capability at near infrared and probably visible wavelengths. We present here the core of any Planet Finder instrument, that is, the extreme adaptive optics (XAO) subsystem. The level of AO correction directly impacts the exposure time required for planet detection. In addition, the capacity of the AO system to calibrate all the instrument static defects ultimately limits detectivity. Hence, the extreme AO system has to adjust for the perturbations induced by the atmospheric turbulence, as well as for the internal aberrations of the instrument itself. We propose a feasibility study for an extreme AO system in the frame of the SPHERE (Spectro-Polarimetry High-contrast Exoplanet Research) instrument, which is currently under design and should equip one of the four VLT 8-m telescopes in 2010.

  7. Nonlinear Optics and Applications

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossin A. (Editor); Frazier, Donald O. (Editor)

    2007-01-01

    Nonlinear optics is the result of laser beam interaction with materials and started with the advent of lasers in the early 1960s. The field is growing daily and plays a major role in emerging photonic technology. Nonlinear optics play a major role in many of the optical applications such as optical signal processing, optical computers, ultrafast switches, ultra-short pulsed lasers, sensors, laser amplifiers, and many others. This special review volume on Nonlinear Optics and Applications is intended for those who want to be aware of the most recent technology. This book presents a survey of the recent advances of nonlinear optical applications. Emphasis will be on novel devices and materials, switching technology, optical computing, and important experimental results. Recent developments in topics which are of historical interest to researchers, and in the same time of potential use in the fields of all-optical communication and computing technologies, are also included. Additionally, a few new related topics which might provoke discussion are presented. The book includes chapters on nonlinear optics and applications; the nonlinear Schrodinger and associated equations that model spatio-temporal propagation; the supercontinuum light source; wideband ultrashort pulse fiber laser sources; lattice fabrication as well as their linear and nonlinear light guiding properties; the second-order EO effect (Pockels), the third-order (Kerr) and thermo-optical effects in optical waveguides and their applications in optical communication; and, the effect of magnetic field and its role in nonlinear optics, among other chapters.

  8. Adaptive Optics for Ground-based Hypertelescopes

    NASA Astrophysics Data System (ADS)

    Labeyrie, Antoine; Borkowski, Virginie; Martinache, Franz; Arnold, Luc; Dejonghe, Julien; Riaud, Pierre; Lardière, Olivier; Gillet, Sophie

    Hypertelescopes, which may be considered as "exploded" versions of an OWL or other ELT, can in principle reach aperture sizes exceeding 1-10 kilometers. They utilize a multi-aperture diluted array and produce direct images through a densified exit pupil. Variants with a flat (the hypertelescope version of the Optical Very Large Array) or spherical (Arecibo-like CARLINA concept) site are studied. Adaptive optics is a major requirement for obtaining direct snapshot images at high resolution. Ways of adapting the Shack-Hartmann and curvature sensing methods for diluted apertures have been proposed. We explore the feasibility of applying 3D Fourier transforms to the dispersed images for extracting the path difference and phase information. With a spherical site, the numerous stars observable simultaneously at large angles can presumably help in the way of atmospheric tomography. Similar optics, equipped with a coronagraph, is proposed to NASA for the Terrestrial Planet Finder. The 3D Fourier transform algorithm also appears applicable in this case for fringe acquisition and π/100 phasing.

  9. Adaptive optics imaging of the retina.

    PubMed

    Battu, Rajani; Dabir, Supriya; Khanna, Anjani; Kumar, Anupama Kiran; Roy, Abhijit Sinha

    2014-01-01

    Adaptive optics is a relatively new tool that is available to ophthalmologists for study of cellular level details. In addition to the axial resolution provided by the spectral-domain optical coherence tomography, adaptive optics provides an excellent lateral resolution, enabling visualization of the photoreceptors, blood vessels and details of the optic nerve head. We attempt a mini review of the current role of adaptive optics in retinal imaging. PubMed search was performed with key words Adaptive optics OR Retina OR Retinal imaging. Conference abstracts were searched from the Association for Research in Vision and Ophthalmology (ARVO) and American Academy of Ophthalmology (AAO) meetings. In total, 261 relevant publications and 389 conference abstracts were identified.

  10. Adaptive optics imaging of the retina

    PubMed Central

    Battu, Rajani; Dabir, Supriya; Khanna, Anjani; Kumar, Anupama Kiran; Roy, Abhijit Sinha

    2014-01-01

    Adaptive optics is a relatively new tool that is available to ophthalmologists for study of cellular level details. In addition to the axial resolution provided by the spectral-domain optical coherence tomography, adaptive optics provides an excellent lateral resolution, enabling visualization of the photoreceptors, blood vessels and details of the optic nerve head. We attempt a mini review of the current role of adaptive optics in retinal imaging. PubMed search was performed with key words Adaptive optics OR Retina OR Retinal imaging. Conference abstracts were searched from the Association for Research in Vision and Ophthalmology (ARVO) and American Academy of Ophthalmology (AAO) meetings. In total, 261 relevant publications and 389 conference abstracts were identified. PMID:24492503

  11. Optical transfer functions derived from solar adaptive optics system data.

    PubMed

    Wöger, Friedrich

    2010-04-01

    Adaptive optics (AO) systems installed at large ground-based telescopes partially correct Earth's atmosphere, making post facto image reconstruction techniques necessary to produce diffraction-limited observations. To achieve accurate photometry in the reconstructed images, some post facto techniques require knowledge of transfer functions that describe the optical system. I present a new, fast method for the estimation of the long-exposure and speckle transfer functions from data gathered by a solar AO system simultaneously with the observations. The results of the presented method are tested with extensive analytical models, demonstrating that the estimation is robust for situations where the AO system is performing with Strehl ratios larger than 45%. Application to observations of solar granulation produces reconstructed images that are photometrically in agreement with earlier results.

  12. Binocular adaptive optics visual simulator.

    PubMed

    Fernández, Enrique J; Prieto, Pedro M; Artal, Pablo

    2009-09-01

    A binocular adaptive optics visual simulator is presented. The instrument allows for measuring and manipulating ocular aberrations of the two eyes simultaneously, while the subject performs visual testing under binocular vision. An important feature of the apparatus consists on the use of a single correcting device and wavefront sensor. Aberrations are controlled by means of a liquid-crystal-on-silicon spatial light modulator, where the two pupils of the subject are projected. Aberrations from the two eyes are measured with a single Hartmann-Shack sensor. As an example of the potential of the apparatus for the study of the impact of the eye's aberrations on binocular vision, results of contrast sensitivity after addition of spherical aberration are presented for one subject. Different binocular combinations of spherical aberration were explored. Results suggest complex binocular interactions in the presence of monochromatic aberrations. The technique and the instrument might contribute to the better understanding of binocular vision and to the search for optimized ophthalmic corrections.

  13. Progress on the VLT Adaptive Optics Facility

    NASA Astrophysics Data System (ADS)

    Arsenault, R.; Madec, P.-Y.; Paufique, J.; Ströbele, S.; Pirard, J.-F.; Vernet, É.; Hackenberg, W.; Hubin, N.; Jochum, L.; Kuntschner, H.; Glindemann, A.; Amico, P.; Lelouarn, M.; Kolb, J.; Tordo, S.; Donaldson, R.; Sã¶Nke, C.; Bonaccini Calia, D.; Conzelmann, R.; Delabre, B.; Kiekebusch, M.; Duhoux, P.; Guidolin, I.; Quattri, M.; Guzman, R.; Buzzoni, B.; Comin, M.; Dupuy, C.; Quentin, J.; Lizon, J.-L.; Silber, A.; Jolly, P.; Manescau, A.; Hammersley, P.; Reyes, J.; Jost, A.; Duchateau, M.; Heinz, V.; Bechet, C.; Stuik, R.

    2010-12-01

    The Very Large Telescope (VLT) Adaptive Optics Facility is a project that will transform one of the VLT's Unit Telescopes into an adaptive telescope that includes a deformable mirror in its optical train. For this purpose the secondary mirror is to be replaced by a thin shell deformable mirror; it will be possible to launch four laser guide stars from the centrepiece and two adaptive optics modules are being developed to feed the instruments HAWK-I and MUSE. These modules implement innovative correction modes for seeing improvement through ground layer adaptive optics and, for high Strehl ratio performance, laser tomography adaptive correction. The performance of these modes will be tested in Europe with a custom test bench called ASSIST. The project has completed its final design phase and concluded an intense phase of procurement; the year 2011 will see the beginning of assembly, integration and tests.

  14. Adaptive optics program at TMT

    NASA Astrophysics Data System (ADS)

    Boyer, C.; Adkins, Sean; Andersen, David R.; Atwood, Jenny; Bo, Yong; Byrnes, Peter; Caputa, Kris; Cavaco, Jeff; Ellerbroek, Brent; Gilles, Luc; Gregory, James; Herriot, Glen; Hickson, Paul; Ljusic, Zoran; Manter, Darren; Marois, Christian; Otárola, Angel; Pagès, Hubert; Schoeck, Matthias; Sinquin, Jean-Christophe; Smith, Malcolm; Spano, Paolo; Szeto, Kei; Tang, Jinlong; Travouillon, Tony; Véran, Jean-Pierre; Wang, Lianqi; Wei, Kai

    2014-07-01

    The TMT first light Adaptive Optics (AO) facility consists of the Narrow Field Infra-Red AO System (NFIRAOS) and the associated Laser Guide Star Facility (LGSF). NFIRAOS is a 60 × 60 laser guide star (LGS) multi-conjugate AO (MCAO) system, which provides uniform, diffraction-limited performance in the J, H, and K bands over 17-30 arc sec diameter fields with 50 per cent sky coverage at the galactic pole, as required to support the TMT science cases. NFIRAOS includes two deformable mirrors, six laser guide star wavefront sensors, and three low-order, infrared, natural guide star wavefront sensors within each client instrument. The first light LGSF system includes six sodium lasers required to generate the NFIRAOS laser guide stars. In this paper, we will provide an update on the progress in designing, modeling and validating the TMT first light AO systems and their components over the last two years. This will include pre-final design and prototyping activities for NFIRAOS, preliminary design and prototyping activities for the LGSF, design and prototyping for the deformable mirrors, fabrication and tests for the visible detectors, benchmarking and comparison of different algorithms and processing architecture for the Real Time Controller (RTC) and development and tests of prototype candidate lasers. Comprehensive and detailed AO modeling is continuing to support the design and development of the first light AO facility. Main modeling topics studied during the last two years include further studies in the area of wavefront error budget, sky coverage, high precision astrometry for the galactic center and other observations, high contrast imaging with NFIRAOS and its first light instruments, Point Spread Function (PSF) reconstruction for LGS MCAO, LGS photon return and sophisticated low order mode temporal filtering.

  15. Hartmann modelling in the discrete spatial-frequency domain: application to real-time reconstruction in adaptive optics

    NASA Astrophysics Data System (ADS)

    Correia, Carlos; Kulcsár, Caroline; Conan, Jean-Marc; Raynaud, Henri-François

    2008-07-01

    Adaptive Optical systems (AO) with a very large number of degrees-of-freedom (DoF) need the proper development of reconstruction and control algorithms mingling both increased performance and reduced computational burden. The Hartmann wave-front sensor (HS-WFS) is broadly used in AO, featuring a set of lenslet arrays aligned onto a Cartesian grid. It works by averaging the slope of the wave-front in each sub-aperture. Throughout this paper the suitability of the so-called Hudgin, Fried and Southwell geometries to model the HS are analysed. Methods of exploiting data obtained from the telescope's annular aperture through the DFT are revisited. An alternative approach based upon the discrete Gerchberg iterative algorithm is employed. It inherently solves the extrapolation and circularization. The inverse problem is regularised to form the minimum mean-square error (MMSE) reconstructor in the spatial-frequency domain. Results obtained through Monte-Carlo simulations allow for a comprehensive comparison to the standard vector-matrix multiplies (VMM/VMMr) algorithm. Computational burden is kept O(DoF log2(DoF)).

  16. Kalman filter based control for Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Petit, Cyril; Quiros-Pacheco, Fernando; Conan, Jean-Marc; Kulcsár, Caroline; Raynaud, Henri-François; Fusco, Thierry

    2004-12-01

    Classical Adaptive Optics suffer from a limitation of the corrected Field Of View. This drawback has lead to the development of MultiConjugated Adaptive Optics. While the first MCAO experimental set-ups are presently under construction, little attention has been paid to the control loop. This is however a key element in the optimization process especially for MCAO systems. Different approaches have been proposed in recent articles for astronomical applications : simple integrator, Optimized Modal Gain Integrator and Kalman filtering. We study here Kalman filtering which seems a very promising solution. Following the work of Brice Leroux, we focus on a frequential characterization of kalman filters, computing a transfer matrix. The result brings much information about their behaviour and allows comparisons with classical controllers. It also appears that straightforward improvements of the system models can lead to static aberrations and vibrations filtering. Simulation results are proposed and analysed thanks to our frequential characterization. Related problems such as model errors, aliasing effect reduction or experimental implementation and testing of Kalman filter control loop on a simplified MCAO experimental set-up could be then discussed.

  17. FPGA-accelerated adaptive optics wavefront control

    NASA Astrophysics Data System (ADS)

    Mauch, S.; Reger, J.; Reinlein, C.; Appelfelder, M.; Goy, M.; Beckert, E.; Tünnermann, A.

    2014-03-01

    The speed of real-time adaptive optical systems is primarily restricted by the data processing hardware and computational aspects. Furthermore, the application of mirror layouts with increasing numbers of actuators reduces the bandwidth (speed) of the system and, thus, the number of applicable control algorithms. This burden turns out a key-impediment for deformable mirrors with continuous mirror surface and highly coupled actuator influence functions. In this regard, specialized hardware is necessary for high performance real-time control applications. Our approach to overcome this challenge is an adaptive optics system based on a Shack-Hartmann wavefront sensor (SHWFS) with a CameraLink interface. The data processing is based on a high performance Intel Core i7 Quadcore hard real-time Linux system. Employing a Xilinx Kintex-7 FPGA, an own developed PCie card is outlined in order to accelerate the analysis of a Shack-Hartmann Wavefront Sensor. A recently developed real-time capable spot detection algorithm evaluates the wavefront. The main features of the presented system are the reduction of latency and the acceleration of computation For example, matrix multiplications which in general are of complexity O(n3 are accelerated by using the DSP48 slices of the field-programmable gate array (FPGA) as well as a novel hardware implementation of the SHWFS algorithm. Further benefits are the Streaming SIMD Extensions (SSE) which intensively use the parallelization capability of the processor for further reducing the latency and increasing the bandwidth of the closed-loop. Due to this approach, up to 64 actuators of a deformable mirror can be handled and controlled without noticeable restriction from computational burdens.

  18. Retinal imaging using adaptive optics technology☆

    PubMed Central

    Kozak, Igor

    2014-01-01

    Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effect of wave front distortions. Retinal imaging using AO aims to compensate for higher order aberrations originating from the cornea and the lens by using deformable mirror. The main application of AO retinal imaging has been to assess photoreceptor cell density, spacing, and mosaic regularity in normal and diseased eyes. Apart from photoreceptors, the retinal pigment epithelium, retinal nerve fiber layer, retinal vessel wall and lamina cribrosa can also be visualized with AO technology. Recent interest in AO technology in eye research has resulted in growing number of reports and publications utilizing this technology in both animals and humans. With the availability of first commercially available instruments we are making transformation of AO technology from a research tool to diagnostic instrument. The current challenges include imaging eyes with less than perfect optical media, formation of normative databases for acquired images such as cone mosaics, and the cost of the technology. The opportunities for AO will include more detailed diagnosis with description of some new findings in retinal diseases and glaucoma as well as expansion of AO into clinical trials which has already started. PMID:24843304

  19. Retinal imaging using adaptive optics technology.

    PubMed

    Kozak, Igor

    2014-04-01

    Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effect of wave front distortions. Retinal imaging using AO aims to compensate for higher order aberrations originating from the cornea and the lens by using deformable mirror. The main application of AO retinal imaging has been to assess photoreceptor cell density, spacing, and mosaic regularity in normal and diseased eyes. Apart from photoreceptors, the retinal pigment epithelium, retinal nerve fiber layer, retinal vessel wall and lamina cribrosa can also be visualized with AO technology. Recent interest in AO technology in eye research has resulted in growing number of reports and publications utilizing this technology in both animals and humans. With the availability of first commercially available instruments we are making transformation of AO technology from a research tool to diagnostic instrument. The current challenges include imaging eyes with less than perfect optical media, formation of normative databases for acquired images such as cone mosaics, and the cost of the technology. The opportunities for AO will include more detailed diagnosis with description of some new findings in retinal diseases and glaucoma as well as expansion of AO into clinical trials which has already started.

  20. Adaptive-optics performance of Antarctic telescopes.

    PubMed

    Lawrence, Jon S

    2004-02-20

    The performance of natural guide star adaptive-optics systems for telescopes located on the Antarctic plateau is evaluated and compared with adaptive-optics systems operated with the characteristic mid-latitude atmosphere found at Mauna Kea. A 2-m telescope with tip-tilt correction and an 8-m telescope equipped with a high-order adaptive-optics system are considered. Because of the large isoplanatic angle of the South Pole atmosphere, the anisoplanatic error associated with an adaptive-optics correction is negligible, and the achievable resolution is determined only by the fitting error associated with the number of corrected wave-front modes, which depends on the number of actuators on the deformable mirror. The usable field of view of an adaptive-optics equipped Antarctic telescope is thus orders of magnitude larger than for a similar telescope located at a mid-latitude site; this large field of view obviates the necessity for multiconjugate adaptive-optics systems that use multiple laser guide stars. These results, combined with the low infrared sky backgrounds, indicate that the Antarctic plateau is the best site on Earth at which to perform high-resolution imaging with large telescopes, either over large fields of view or with appreciable sky coverage. Preliminary site-testing results obtained recently from the Dome Concordia station indicate that this site is far superior to even the South Pole.

  1. Small scale adaptive optics experiment systems engineering

    NASA Technical Reports Server (NTRS)

    Boykin, William H.

    1993-01-01

    Assessment of the current technology relating to the laser power beaming system which in full scale is called the Beam Transmission Optical System (BTOS). Evaluation of system integration efforts are being conducted by the various government agencies and industry. Concepts are being developed for prototypes of adaptive optics for a BTOS.

  2. Integrated optomechanical analysis of adaptive optical systems

    NASA Astrophysics Data System (ADS)

    Doyle, Keith B.; Genberg, Victor L.; Michels, Gregory J.

    2004-01-01

    A method to predict performance of adaptive optical systems subject to mechanical perturbations is presented. Integrated modeling techniques coupling finite element analysis and optical design software are discussed that enable mechanical design trades of an adaptive mirror assembly based on correctability of the optical system wavefront error. This method is based on the linearity of wavefront error consistent with that caused by mechanical disturbances during operation. Optical surface sensitivities are computed based on rigid-body and higher-order surface deformations that relate mechanical surface errors to optical system wavefront error. The sensitivities are then used to determine the best-fit set of actuators to minimize the wavefront error in the optical system due to finite element derived mechanical disturbances. An example is demonstrated for a Cassegrain telescope with an active primary mirror.

  3. Horizontal path laser communications employing MEMS adaptive optics correction

    NASA Astrophysics Data System (ADS)

    Thompson, Charles A.; Wilks, Scott C.; Brase, James M.; Young, Richard A.; Johnson, Gary W.; Ruggiero, Anthony J.

    2002-02-01

    Horizontal path laser communications are beginning to provide attractive alternatives for high-speed optical communications. In particular, companies are beginning to sell fiberless alternatives for intranet and sporting event video. These applications are primarily aimed at short distance applications (on the order of 1 km pathlength). There exists a potential need to extend this pathlength to distances much greater than a 1km. For cases of long distance optical propagation, atmospheric turbulence will ultimately limit the maximum achievable data rate. In this paper, we propose a method of improved signal quality through the use of adaptive optics. In particular, we show work in progress toward a high-speed, small footprint Adaptive Optics system for horizontal path laser communications. Such a system relies heavily on recent progress in Micro-Electro-Mechanical Systems (MEMS) deformable mirrors as well as improved communication and computational components. In this paper we detail two Adaptive Optics approaches for improved through-put, the first is the compensated receiver (the traditional Adaptive Optics approach), the second is the compensated transmitter/receiver. The second approach allows for correction of the optical wavefront before transmission from the transmitter and prior to detection at the receiver.

  4. Horizontal Path Laser Communications Employing MEMS Adaptive Optics Correction

    SciTech Connect

    Thompson, C A; Wilks, S C; Brase, J M; Young, R A; Johnson, G W; Ruggiero, A J

    2001-09-05

    Horizontal path laser communications are beginning to provide attractive alternatives for high-speed optical communications, In particular, companies are beginning to sell fiberless alternatives for intranet and sporting event video. These applications are primarily aimed at short distance applications (on the order of 1 km pathlength). There exists a potential need to extend this pathlength to distances much greater than a 1km. For cases of long distance optical propagation, atmospheric turbulence will ultimately limit the maximum achievable data rate. In this paper, we propose a method of improved signal quality through the use of adaptive optics. In particular, we show work in progress toward a high-speed, small footprint Adaptive Optics system for horizontal path laser communications. Such a system relies heavily on recent progress in Micro-Electro-Mechanical Systems (MEMS) deformable mirrors as well as improved communication and computational components. In this paper we detail two Adaptive Optics approaches for improved through-put, the first is the compensated receiver (the traditional Adaptive Optics approach), the second is the compensated transmitter/receiver. The second approach allows for correction of the optical wavefront before transmission from the transmitter and prior to detection at the receiver.

  5. Toward Adaptive Optic Mitigation of Aero-Optic Effects

    DTIC Science & Technology

    2009-02-27

    photography .[43] Tyson developed expressions for the "gain" of a deformable mirror removing Zernike modes within an aperture. [35] The following...R.K., Principles of Adaptive Optics, Academic Press, Inc., San Diego, 1991. 9. Tyson, R.K., The status of astronomical adaptive optics systems...pin-hole photography The London, Edinburg and Dublin philosophical magazine and journal of science 31 87-99 44. Siegenthaler, J., Guidelines for

  6. Optical Design and Optimization of Translational Reflective Adaptive Optics Ophthalmoscopes

    NASA Astrophysics Data System (ADS)

    Sulai, Yusufu N. B.

    The retina serves as the primary detector for the biological camera that is the eye. It is composed of numerous classes of neurons and support cells that work together to capture and process an image formed by the eye's optics, which is then transmitted to the brain. Loss of sight due to retinal or neuro-ophthalmic disease can prove devastating to one's quality of life, and the ability to examine the retina in vivo is invaluable in the early detection and monitoring of such diseases. Adaptive optics (AO) ophthalmoscopy is a promising diagnostic tool in early stages of development, still facing significant challenges before it can become a clinical tool. The work in this thesis is a collection of projects with the overarching goal of broadening the scope and applicability of this technology. We begin by providing an optical design approach for AO ophthalmoscopes that reduces the aberrations that degrade the performance of the AO correction. Next, we demonstrate how to further improve image resolution through the use of amplitude pupil apodization and non-common path aberration correction. This is followed by the development of a viewfinder which provides a larger field of view for retinal navigation. Finally, we conclude with the development of an innovative non-confocal light detection scheme which improves the non-invasive visualization of retinal vasculature and reveals the cone photoreceptor inner segments in healthy and diseased eyes.

  7. Pulse front adaptive optics in multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Sun, B.; Salter, P. S.; Booth, M. J.

    2016-03-01

    The accurate focusing of ultrashort laser pulses is extremely important in multiphoton microscopy. Using adaptive optics to manipulate the incident ultrafast beam in either the spectral or spatial domain can introduce significant benefits when imaging. Here we introduce pulse front adaptive optics: manipulating an ultrashort pulse in both the spatial and temporal domains. A deformable mirror and a spatial light modulator are operated in concert to modify contours of constant intensity in space and time within an ultrashort pulse. Through adaptive control of the pulse front, we demonstrate an enhancement in the measured fluorescence from a two photon microscope.

  8. Optical Profilometers Using Adaptive Signal Processing

    NASA Technical Reports Server (NTRS)

    Hall, Gregory A.; Youngquist, Robert; Mikhael, Wasfy

    2006-01-01

    A method of adaptive signal processing has been proposed as the basis of a new generation of interferometric optical profilometers for measuring surfaces. The proposed profilometers would be portable, hand-held units. Sizes could be thus reduced because the adaptive-signal-processing method would make it possible to substitute lower-power coherent light sources (e.g., laser diodes) for white light sources and would eliminate the need for most of the optical components of current white-light profilometers. The adaptive-signal-processing method would make it possible to attain scanning ranges of the order of decimeters in the proposed profilometers.

  9. Optical and control modeling for adaptive beam-combining experiments

    SciTech Connect

    Gruetzner, J.K.; Tucker, S.D.; Neal, D.R.; Bentley, A.E.; Simmons-Potter, K.

    1995-08-01

    The development of modeling algorithms for adaptive optics systems is important for evaluating both performance and design parameters prior to system construction. Two of the most critical subsystems to be modeled are the binary optic design and the adaptive control system. Since these two are intimately related, it is beneficial to model them simultaneously. Optic modeling techniques have some significant limitations. Diffraction effects directly limit the utility of geometrical ray-tracing models, and transform techniques such as the fast fourier transform can be both cumbersome and memory intensive. The authors have developed a hybrid system incorporating elements of both ray-tracing and fourier transform techniques. In this paper they present an analytical model of wavefront propagation through a binary optic lens system developed and implemented at Sandia. This model is unique in that it solves the transfer function for each portion of a diffractive optic analytically. The overall performance is obtained by a linear superposition of each result. The model has been successfully used in the design of a wide range of binary optics, including an adaptive optic for a beam combining system consisting of an array of rectangular mirrors, each controllable in tip/tilt and piston. Wavefront sensing and the control models for a beam combining system have been integrated and used to predict overall systems performance. Applicability of the model for design purposes is demonstrated with several lens designs through a comparison of model predictions with actual adaptive optics results.

  10. The Coming of Age of Adaptive Optics

    NASA Astrophysics Data System (ADS)

    1995-10-01

    How Ground-Based Astronomers Beat the Atmosphere Adaptive Optics (AO) is the new ``wonder-weapon'' in ground-based astronomy. By means of advanced electro-optical devices at their telescopes, astronomers are now able to ``neutralize'' the image-smearing turbulence of the terrestrial atmosphere (seen by the unaided eye as the twinkling of stars) so that much sharper images can be obtained than before. In practice, this is done with computer-controlled, flexible mirrors which refocus the blurred images up to 100 times per second, i.e. at a rate that is faster than the changes in the atmospheric turbulence. This means that finer details in astronomical objects can be studied and also - because of the improved concentration of light in the telescope's focal plane - that fainter objects can be observed. At the moment, Adaptive Optics work best in the infrared part of spectrum, but at some later time it may also significantly improve observations at the shorter wavelengths of visible light. The many-sided aspects of this new technology and its impact on astronomical instrumentation was the subject of a recent AO conference [1] with over 150 participants from about 30 countries, presenting a total of more than 100 papers. The Introduction of AO Techniques into Astronomy The scope of this meeting was the design, fabrication and testing of AO systems, characterisation of the sources of atmospheric disturbance, modelling of compensation systems, individual components, astronomical AO results, non-astronomical applications, laser guide star systems, non-linear optical phase conjugation, performance evaluation, and other areas of this wide and complex field, in which front-line science and high technology come together in a new and powerful symbiosis. One of the specific goals of the meeting was to develop contacts between AO scientists and engineers in the western world and their colleagues in Russia and Asia. For the first time at a conference of this type, nine Russian

  11. Accuracy requirements of optical linear algebra processors in adaptive optics imaging systems

    NASA Technical Reports Server (NTRS)

    Downie, John D.

    1990-01-01

    A ground-based adaptive optics imaging telescope system attempts to improve image quality by detecting and correcting for atmospherically induced wavefront aberrations. The required control computations during each cycle will take a finite amount of time. Longer time delays result in larger values of residual wavefront error variance since the atmosphere continues to change during that time. Thus an optical processor may be well-suited for this task. This paper presents a study of the accuracy requirements in a general optical processor that will make it competitive with, or superior to, a conventional digital computer for the adaptive optics application. An optimization of the adaptive optics correction algorithm with respect to an optical processor's degree of accuracy is also briefly discussed.

  12. Practical issues for the use of liquid crystal spatial light modulators in adaptive optics

    NASA Astrophysics Data System (ADS)

    Bold, G. T.; Barnes, T. H.; Gourlay, J.; Sharples, R. M.; Haskell, T. G.

    1998-03-01

    Low cost, accurate, high resolution spatial light modulators are of increasing interest for adaptive optics applications. Most adaptive optics systems currently use expensive segmented or deformable mirrors. Nematic liquid crystal spatial light modulators have been suggested as possible substitutes for these mirrors as the phase modulating arrays in adaptive optics systems. This paper discusses broad wavelength band, and polarisation insensitive operation of two different liquid crystal spatial light modulators currently available and under investigation as possible phase modulating arrays for adaptive optics systems. The results of our investigations give a good indication of how the devices will operate in practical adaptive optics systems.

  13. Liquid lens: advances in adaptive optics

    NASA Astrophysics Data System (ADS)

    Casey, Shawn Patrick

    2010-12-01

    'Liquid lens' technologies promise significant advancements in machine vision and optical communications systems. Adaptations for machine vision, human vision correction, and optical communications are used to exemplify the versatile nature of this technology. Utilization of liquid lens elements allows the cost effective implementation of optical velocity measurement. The project consists of a custom image processor, camera, and interface. The images are passed into customized pattern recognition and optical character recognition algorithms. A single camera would be used for both speed detection and object recognition.

  14. Adaptive optical microscope for brain imaging in vivo

    NASA Astrophysics Data System (ADS)

    Wang, Kai

    2017-04-01

    The optical heterogeneity of biological tissue imposes a major limitation to acquire detailed structural and functional information deep in the biological specimens using conventional microscopes. To restore optimal imaging performance, we developed an adaptive optical microscope based on direct wavefront sensing technique. This microscope can reliably measure and correct biological samples induced aberration. We demonstrated its performance and application in structural and functional brain imaging in various animal models, including fruit fly, zebrafish and mouse.

  15. PSF halo reduction in adaptive optics using dynamic pupil masking.

    PubMed

    Osborn, James; Myers, Richard M; Love, Gordon D

    2009-09-28

    We describe a method to reduce residual speckles in an adaptive optics system which add to the halo of the point spread function (PSF). The halo is particularly problematic in astronomical applications involving the detection of faint companions. Areas of the pupil are selected where the residual wavefront aberrations are large and these are masked using a spatial light modulator. The method is also suitable for smaller telescopes without adaptive optics as a relatively simple method to increase the resolution of the telescope. We describe the principle of the technique and show simulation results.

  16. Impact of Liquid Crystals in Active and Adaptive Optics

    PubMed Central

    Arines, Justo

    2009-01-01

    Active and dynamic modulation of light has been one of major contributions of liquid crystals to Optics. The spectrum of application range from signposting panels to high resolution imaging. The development of new materials is the key to continued progress in this field. To promote this we will present in this paper recent uses of liquid crystals as active or adaptive modulators of light. Besides, we will reflect on their current limitations. We expect with this to contribute to the progress in the field of liquid crystals and thus the development of new useful tools for Active and Adaptive Optics.

  17. Adaptive Optical Linear Algebra Processors

    DTIC Science & Technology

    1988-11-15

    which was very small, CNR = CGS = 10-5). For this case study, only r=3 Newton - Rapshon iterations were required for convergence. Thus, the algorithm...realizations of the Newton -Raphson method for nonlinear equations and a new optical LU direct decomposition and Gauss-Seidel iterative solution to the...We linearize the nonlinear equations by the Newton -Raphson method, which generates a set of LAEs that we solve by iterative and direct methods. We

  18. Thin, nearly wireless adaptive optical device

    NASA Technical Reports Server (NTRS)

    Knowles, Gareth (Inventor); Hughes, Eli (Inventor)

    2008-01-01

    A thin, nearly wireless adaptive optical device capable of dynamically modulating the shape of a mirror in real time to compensate for atmospheric distortions and/or variations along an optical material is provided. The device includes an optical layer, a substrate, at least one electronic circuit layer with nearly wireless architecture, an array of actuators, power electronic switches, a reactive force element, and a digital controller. Actuators are aligned so that each axis of expansion and contraction intersects both substrate and reactive force element. Electronics layer with nearly wireless architecture, power electronic switches, and digital controller are provided within a thin-film substrate. The size and weight of the adaptive optical device is solely dominated by the size of the actuator elements rather than by the power distribution system.

  19. Thin nearly wireless adaptive optical device

    NASA Technical Reports Server (NTRS)

    Knowles, Gareth J. (Inventor); Hughes, Eli (Inventor)

    2009-01-01

    A thin nearly wireless adaptive optical device capable of dynamically modulating the shape of a mirror in real time to compensate for atmospheric distortions and/or variations along an optical material is provided. The device includes an optical layer, a substrate, at least one electronic circuit layer with nearly wireless architecture, an array of actuators, power electronic switches, a reactive force element, and a digital controller. Actuators are aligned so that each axis of expansion and contraction intersects both substrate and reactive force element. Electronics layer with nearly wireless architecture, power electronic switches, and digital controller are provided within a thin-film substrate. The size and weight of the adaptive optical device is solely dominated by the size of the actuator elements rather than by the power distribution system.

  20. Thin, nearly wireless adaptive optical device

    NASA Technical Reports Server (NTRS)

    Knowles, Gareth (Inventor); Hughes, Eli (Inventor)

    2007-01-01

    A thin, nearly wireless adaptive optical device capable of dynamically modulating the shape of a mirror in real time to compensate for atmospheric distortions and/or variations along an optical material is provided. The device includes an optical layer, a substrate, at least one electronic circuit layer with nearly wireless architecture, an array of actuators, power electronic switches, a reactive force element, and a digital controller. Actuators are aligned so that each axis of expansion and contraction intersects both substrate and reactive force element. Electronics layer with nearly wireless architecture, power electronic switches, and digital controller are provided within a thin-film substrate. The size and weight of the adaptive optical device is solely dominated by the size of the actuator elements rather than by the power distribution system.

  1. Adaptive optics requirements definition for TMT

    NASA Astrophysics Data System (ADS)

    Dekany, Richard G.; Britton, Matthew C.; Gavel, Don T.; Ellerbroek, Brent L.; Herriot, Glen; Max, Claire E.; Veran, Jean-Pierre

    2004-10-01

    The scientific return on adaptive optics on large telescopes has generated a new vocabulary of different adaptive optics (AO) modalities. Multiobject AO (MOAO), multiconjugate AO (MCAO), ground-layer AO (GLAO), and extreme contrast AO (ExAO) each require complex new extensions in functional requirements beyond the experience gained with systems operational on large telescopes today. Because of this potential for increased complexity, a more formal requirements development process is recommended. We describe a methodology for requirements definition under consideration and summarize the current scientific prioritization of TMT AO capabilities.

  2. Adaptive ranging for optical coherence tomography

    PubMed Central

    Iftimia, N. V.; Bouma, B. E.; de Boer, J. F.; Park, B. H.; Cense, B.; Tearney, G. J.

    2009-01-01

    At present, optical coherence tomography systems have a limited imaging depth or axial scan range, making diagnosis of large diameter arterial vessels and hollow organs difficult. Adaptive ranging is a feedback technique where image data is utilized to adjust the coherence gate offset and range. In this paper, we demonstrate an adaptive optical coherence tomography system with a 7.0 mm range. By matching the imaging depth to the approximately 1.5 mm penetration depth in tissue, a 3 dB sensitivity improvement over conventional imaging systems with a 3.0 mm imaging depth was realized. PMID:19483942

  3. PASSATA: object oriented numerical simulation software for adaptive optics

    NASA Astrophysics Data System (ADS)

    Agapito, G.; Puglisi, A.; Esposito, S.

    2016-07-01

    We present the last version of the PyrAmid Simulator Software for Adaptive opTics Arcetri (PASSATA), an IDL and CUDA based object oriented software developed in the Adaptive Optics group of the Arcetri observatory for Monte-Carlo end-to-end adaptive optics simulations. The original aim of this software was to evaluate the performance of a single conjugate adaptive optics system for ground based telescope with a pyramid wavefront sensor. After some years of development, the current version of PASSATA is able to simulate several adaptive optics systems: single conjugate, multi conjugate and ground layer, with Shack Hartmann and Pyramid wavefront sensors. It can simulate from 8m to 40m class telescopes, with diffraction limited and resolved sources at finite or infinite distance from the pupil. The main advantages of this software are the versatility given by the object oriented approach and the speed given by the CUDA implementation of the most computational demanding routines. We describe the software with its last developments and present some examples of application.

  4. Adaptive optical antennas: design and evaluation

    NASA Astrophysics Data System (ADS)

    Weyrauch, Thomas; Vorontsov, Mikhail A.; Carhart, Gary W.; Simonova, Galina V.; Beresnev, Leonid A.; Polnau, Ernst E.

    2007-09-01

    We present the design and evaluation of compact adaptive optical antennas with apertures diameters of 16 mm and 100 mm for 5Gbit/s-class free-space optical communication systems. The antennas provide a bi-directional optically transparent link between fiber-optical wavelength-division multiplex systems and allow for mitigation of atmospheric-turbulence induced wavefront phase distortions with adaptive optics components. Beam steering is implemented in the antennas either with mirrors on novel tip/tilt platforms or a fiber-tip positioning system, both enabling operation bandwidths of more than 1 kHz. Bimorph piezoelectric actuated deformable mirrors are used for low-order phase-distortion compensation. An imaging system is integrated in the antennas for coarse pointing and tracking. Beam steering and wavefront control is based on blind maximization of the received signal level using a stochastic parallel gradient descent algorithm. The adaptive optics control architecture allowed the use of feedback signals provided locally within each transceiver system and remotely by the opposite transceiver system via an RF link. First atmospheric compensation results from communication experiments over a 250 m near-ground propagation path are presented.

  5. Coherent Optical Adaptive Techniques (COAT)

    DTIC Science & Technology

    1973-02-01

    E o U rt UJ c t- 3 c o ■p t) c u •H +» ft o \\ o •d H & ■H to ■ o 10 ..,. J,.-. ..»^-^A^.^-. mfiiTflMaaj— ft ! -^^ lUMI IJI...13) 2 2 2 J,(Tidp) array r n=-oo e e ^ a Jl( XR ^o +yo j o vo E 5 n--ae 0 n\\/-N , TTD XB - i 0 sinc XR Xo ( ft ...was found that the acousto-optic Bragg cell functioning as a frequency modulator can meet the unlimited dynamic range and bandwidth requirements

  6. Pulse front control with adaptive optics

    NASA Astrophysics Data System (ADS)

    Sun, B.; Salter, P. S.; Booth, M. J.

    2016-03-01

    The focusing of ultrashort laser pulses is extremely important for processes including microscopy, laser fabrication and fundamental science. Adaptive optic elements, such as liquid crystal spatial light modulators or membrane deformable mirrors, are routinely used for the correction of aberrations in these systems, leading to improved resolution and efficiency. Here, we demonstrate that adaptive elements used with ultrashort pulses should not be considered simply in terms of wavefront modification, but that changes to the incident pulse front can also occur. We experimentally show how adaptive elements may be used to engineer pulse fronts with spatial resolution.

  7. Implementations of adaptive associative optical computing elements

    NASA Astrophysics Data System (ADS)

    Fisher, Arthur D.; Lee, John N.; Fukuda, Robert C.

    1986-01-01

    The present optical implementations for heteroassociative memory modules, which are capable of real time adaptive learning, are pertinent to the eventual construction of large, multimodule associative/neural network architectures that can consider problems in the acquisition, transformation, matching/recognition, and manipulation of large amounts of data in parallel. These modules offer such performance features as convergence to the least-squares-optimum pseudoinverse association, accumulative and gated learning, forgetfulness of unused associations, resistance to dynamic-range saturation, and compensation of optical system aberrations. Optics uniquely furnish the massive parallel interconnection paths required to cascade and interconnect a number of modules to form the more sophisticated multiple module architectures.

  8. Adaptive Optics Technology for High-Resolution Retinal Imaging

    PubMed Central

    Lombardo, Marco; Serrao, Sebastiano; Devaney, Nicholas; Parravano, Mariacristina; Lombardo, Giuseppe

    2013-01-01

    Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of optical aberrations. The direct visualization of the photoreceptor cells, capillaries and nerve fiber bundles represents the major benefit of adding AO to retinal imaging. Adaptive optics is opening a new frontier for clinical research in ophthalmology, providing new information on the early pathological changes of the retinal microstructures in various retinal diseases. We have reviewed AO technology for retinal imaging, providing information on the core components of an AO retinal camera. The most commonly used wavefront sensing and correcting elements are discussed. Furthermore, we discuss current applications of AO imaging to a population of healthy adults and to the most frequent causes of blindness, including diabetic retinopathy, age-related macular degeneration and glaucoma. We conclude our work with a discussion on future clinical prospects for AO retinal imaging. PMID:23271600

  9. Adaptive optics technology for high-resolution retinal imaging.

    PubMed

    Lombardo, Marco; Serrao, Sebastiano; Devaney, Nicholas; Parravano, Mariacristina; Lombardo, Giuseppe

    2012-12-27

    Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of optical aberrations. The direct visualization of the photoreceptor cells, capillaries and nerve fiber bundles represents the major benefit of adding AO to retinal imaging. Adaptive optics is opening a new frontier for clinical research in ophthalmology, providing new information on the early pathological changes of the retinal microstructures in various retinal diseases. We have reviewed AO technology for retinal imaging, providing information on the core components of an AO retinal camera. The most commonly used wavefront sensing and correcting elements are discussed. Furthermore, we discuss current applications of AO imaging to a population of healthy adults and to the most frequent causes of blindness, including diabetic retinopathy, age-related macular degeneration and glaucoma. We conclude our work with a discussion on future clinical prospects for AO retinal imaging.

  10. Adaptive Optics at the World’s Biggest Optical Telescope

    DTIC Science & Technology

    2010-09-01

    bottom up. The reflective, and deformable, component of each of the LBT’s mirrors is a concave Zerodur shell, 1.6 mm in average thickness and 911 mm in...Physik, 85748 Garching, Germany ABSTRACT The Large Binocular Telescope (LBT) on Mt. Graham, Arizona, comprises two 8.4 m primary mirrors on a...adaptive optics (AO) was incorporated into the design through two adaptive secondary mirrors (ASM), each 91 cm in diameter with 672 actuators, which feed

  11. Adaptive Optics: A Pandora's box for Photometry

    NASA Astrophysics Data System (ADS)

    Roberts, L. C., Jr.; ten Brummelaar, T. A.; Mason, B. D.

    1998-01-01

    In conjunction with the long running CHARA speckle program, CHARA has begun using Adaptive Optics to study binary stars. Most of this work has focused on determining differential magnitudes for binary stars. CHARA was awarded six nights on the 1.5 meter at the Starfire Optical Range (SOR) in 1995. Since then CHARA has begun observing with the Mt Wilson Institute Adaptive Optics (MWI-AO) system on the Hooker 100-inch telescope at Mt. Wilson Observatory. While attempting to estimate error bars on the differential magnitudes it was noticed that frames of the same object taken sequentially produce discrepant images and results. As this may be related to the specific AO system comparisons between SOR and MWI-AO data are made for stars that were observed with both systems. Also, comparisons are made between stars observed multiple times with the MWI-AO system. The results of this investigation are presented.

  12. Demonstration of portable solar adaptive optics system

    NASA Astrophysics Data System (ADS)

    Ren, Deqing; Dong, Bing

    2012-10-01

    Solar-adaptive optics (AO) are more challenging than night-time AO, in some aspects. A portable solar adaptive optics (PSAO) system featuring compact physical size, low cost, and good performance has been proposed and developed. PSAO can serve as a visiting instrument for any existing ground-based solar telescope to improve solar image quality by replacing just a few optical components. High-level programming language, LabVIEW, is used to develop the wavefront sensing and control software, and general purpose computers are used to drive the whole system. During October 2011, the feasibility and good performance of PSAO was demonstrated with the 61-cm solar telescope at San Fernando Observatory. The image contrast and resolution are noticeably improved after AO correction.

  13. Simulation of DKIST solar adaptive optics system

    NASA Astrophysics Data System (ADS)

    Marino, Jose; Carlisle, Elizabeth; Schmidt, Dirk

    2016-07-01

    Solar adaptive optics (AO) simulations are a valuable tool to guide the design and optimization process of current and future solar AO and multi-conjugate AO (MCAO) systems. Solar AO and MCAO systems rely on extended object cross-correlating Shack-Hartmann wavefront sensors to measure the wavefront. Accurate solar AO simulations require computationally intensive operations, which have until recently presented a prohibitive computational cost. We present an update on the status of a solar AO and MCAO simulation tool being developed at the National Solar Observatory. The simulation tool is a multi-threaded application written in the C++ language that takes advantage of current large multi-core CPU computer systems and fast ethernet connections to provide accurate full simulation of solar AO and MCAO systems. It interfaces with KAOS, a state of the art solar AO control software developed by the Kiepenheuer-Institut fuer Sonnenphysik, that provides reliable AO control. We report on the latest results produced by the solar AO simulation tool.

  14. Digital adaptation algorithms of adaptive optics corrected images

    NASA Astrophysics Data System (ADS)

    Polskikh, Sergey D.; Sviridov, Konstantin N.

    2000-07-01

    The technology is considered of space object image obtainment with high angular resolution, based on the adaptive tuning of image spatial spectra (digital adaptation), corrected by adaptive optics. As the basis of the technology, the algorithm is taken of the integral equation of the I-st kind of convolution type with unknown core and imprecisely given right part. It's shown the procedure of the inverse operator construction for this equation solution is connected with minimization of nonlinear regularizing multiextremel functionals and could be realized on the base of global optimization methods. The structure of multiextremel functionals is analyzed, and the main global extremum search methods are researched. It is shown, that as the basis of the optimal construction of the channel for the obtainment of images with high resolution, the principle must be taken of the sequential reduction of the global extremum search space dimensionality, and what's more, the predetector processing of the wavefront by the adaptive optics is the first stage of this reduction. The results are given of numerical modelling including the examples of the distorted and restorated images of model objects under different signal-to-noise ratios.

  15. Adaptive optics assisted reconfigurable liquid-driven optical switch

    NASA Astrophysics Data System (ADS)

    Fuh, Yiin-Kuen; Huang, Wei-Chi

    2013-07-01

    This study demonstrates a mechanical-based, liquid-driven optical switch integrated with adaptive optics and a reconfigurable black liquid (dye-doped liquid). The device aperture can be continuously tuned between 0.6 and 6.9 mm, precisely achieved by a syringe pump for volume control. Adaptive optics (AO) capability and possible enhancement of the lost power intensity of the ink-polluted glass plate have also been experimentally investigated. While measuring power intensity with/without AO indicates only a marginal difference of ˜1%, a significant difference of 3 s in the response characteristic of "switching on" time can be observed. An extremely high contrast ratio of ˜105 for a red-colored light is achieved.

  16. Multiconjugate adaptive optics for the Swedish ELT

    NASA Astrophysics Data System (ADS)

    Gontcharov, Alexander; Owner-Petersen, Mette

    2000-08-01

    The Swedish ELT is intended to be a 50 m telescope with multiconjugate adaptive optics integrated directly as a crucial part of the optical design. In this paper we discuss the effects of the distributed atmospheric turbulence with regard to the choice of optimal geometry of the telescope. Originally the basic system was foreseen to be a Gregorian with an adaptive secondary correcting adequately for nearby turbulences in both the infrared and visual regions, but if the performance degradation expected from changing the basic system to a Cassegrain keeping the adaptive secondary could be accepted, the constructional costs would be significantly reduced. In order to clarify this question, a simple analytical model describing the performance employing a single deformable mirror for adaptive correction has been developed and used for analysis. The quantitative results shown here relates to a wavelength of 2.2 micrometers and are based on the seven layer atmospheric model for the Cerro Pachon site, which is believed to be a good representative of most good astronomical sites. As a consequence of the analysis no performance degradation is expected from changing the core telescope to a Cassegrain (Ritchey- Chretien). The paper presents the layout and optical performance of the new design.

  17. Adaptive Optics for Radio Interferometers

    NASA Astrophysics Data System (ADS)

    Woody, David P.; Bock, Douglas; Lamb, James W.; Plambeck, Richard; Wootten, Al; Paine, Scott; Butler, Bryan; Carpenter, John

    2009-03-01

    Radio interferometry has the potential to achieve milliarcsecond resolution of important astrophysical processes, but a significant impediment, particularly at millimeter and submillimeter wavelengths, is the scintillation due to turbulence in the troposphere. Since this is largely due to water vapor, considerable effort has been put into measuring absolute humidity along the line of sight of observations to derive corrections for the delay fluctuations. Alternatively, measurement of atmospheric delay variations by observing a bright point-like calibrator close to the science target has been investigated as a more direct probe of refractive index changes. While great strides have been made in the instrumentation and application of the results, the goal of a robust, reliable seeing correction remains elusive. Full realization of the potentials of these techniques will require a concerted effort to understand the complex behavior of the atmosphere, including the wet and dry components. Over the next few years we expect close collaboration among the radio astronomy community, as well as the meteorological community, to achieve significant progress towards routine high-resolution interferometry.

  18. [Technical principles of adaptive optics in ophthalmology].

    PubMed

    Reiniger, J L; Domdei, N; Holz, F G; Harmening, W M

    2017-03-01

    During the last 25 years ophthalmic imaging has undergone a revolution. This review gives an overview of the possibilities of adaptive optics (AO) for ophthalmic imaging technologies and their development and illustrates that the role of ophthalmic imaging changed from the documentation of obvious abnormalities to the detection of microscopic yet significant conspicuities. This enables earlier and more precise diagnoses. The implementation of AO for imaging systems like fundus cameras, scanning laser ophthalmoscopy and optical coherence tomography has gained in importance. In recent years a couple of companies started developing commercially available AO systems, thus, indicating a future use in clinical routine.

  19. Lens based adaptive optics scanning laser ophthalmoscope.

    PubMed

    Felberer, Franz; Kroisamer, Julia-Sophie; Hitzenberger, Christoph K; Pircher, Michael

    2012-07-30

    We present an alternative approach for an adaptive optics scanning laser ophthalmoscope (AO-SLO). In contrast to other commonly used AO-SLO instruments, the imaging optics consist of lenses. Images of the fovea region of 5 healthy volunteers are recorded. The system is capable to resolve human foveal cones in 3 out of 5 healthy volunteers. Additionally, we investigated the capability of the system to support larger scanning angles (up to 5°) on the retina. Finally, in order to demonstrate the performance of the instrument images of rod photoreceptors are presented.

  20. High-efficiency Autonomous Laser Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Baranec, Christoph; Riddle, Reed; Law, Nicholas M.; Ramaprakash, A. N.; Tendulkar, Shriharsh; Hogstrom, Kristina; Bui, Khanh; Burse, Mahesh; Chordia, Pravin; Das, Hillol; Dekany, Richard; Kulkarni, Shrinivas; Punnadi, Sujit

    2014-07-01

    As new large-scale astronomical surveys greatly increase the number of objects targeted and discoveries made, the requirement for efficient follow-up observations is crucial. Adaptive optics imaging, which compensates for the image-blurring effects of Earth's turbulent atmosphere, is essential for these surveys, but the scarcity, complexity and high demand of current systems limit their availability for following up large numbers of targets. To address this need, we have engineered and implemented Robo-AO, a fully autonomous laser adaptive optics and imaging system that routinely images over 200 objects per night with an acuity 10 times sharper at visible wavelengths than typically possible from the ground. By greatly improving the angular resolution, sensitivity, and efficiency of 1-3 m class telescopes, we have eliminated a major obstacle in the follow-up of the discoveries from current and future large astronomical surveys.

  1. Adaptive Optics Imaging of Solar System Objects

    NASA Technical Reports Server (NTRS)

    Roddier, Francois; Owen, Toby

    1997-01-01

    Most solar system objects have never been observed at wavelengths longer than the R band with an angular resolution better than 1 sec. The Hubble Space Telescope itself has only recently been equipped to observe in the infrared. However, because of its small diameter, the angular resolution is lower than that one can now achieved from the ground with adaptive optics, and time allocated to planetary science is limited. We have been using adaptive optics (AO) on a 4-m class telescope to obtain 0.1 sec resolution images solar system objects at far red and near infrared wavelengths (0.7-2.5 micron) which best discriminate their spectral signatures. Our efforts has been put into areas of research for which high angular resolution is essential, such as the mapping of Titan and of large asteroids, the dynamics and composition of Neptune stratospheric clouds, the infrared photometry of Pluto, Charon, and close satellites previously undetected from the ground.

  2. HIGH-EFFICIENCY AUTONOMOUS LASER ADAPTIVE OPTICS

    SciTech Connect

    Baranec, Christoph; Riddle, Reed; Tendulkar, Shriharsh; Hogstrom, Kristina; Bui, Khanh; Dekany, Richard; Kulkarni, Shrinivas; Law, Nicholas M.; Ramaprakash, A. N.; Burse, Mahesh; Chordia, Pravin; Das, Hillol; Punnadi, Sujit

    2014-07-20

    As new large-scale astronomical surveys greatly increase the number of objects targeted and discoveries made, the requirement for efficient follow-up observations is crucial. Adaptive optics imaging, which compensates for the image-blurring effects of Earth's turbulent atmosphere, is essential for these surveys, but the scarcity, complexity and high demand of current systems limit their availability for following up large numbers of targets. To address this need, we have engineered and implemented Robo-AO, a fully autonomous laser adaptive optics and imaging system that routinely images over 200 objects per night with an acuity 10 times sharper at visible wavelengths than typically possible from the ground. By greatly improving the angular resolution, sensitivity, and efficiency of 1-3 m class telescopes, we have eliminated a major obstacle in the follow-up of the discoveries from current and future large astronomical surveys.

  3. Adaptive Optics Imaging of Solar System Objects

    NASA Technical Reports Server (NTRS)

    Roddier, Francois; Owen, Toby

    1999-01-01

    Most solar system objects have never been observed at wavelengths longer than the R band with an angular resolution better than 1". The Hubble Space Telescope itself has only recently been equipped to observe in the infrared. However, because of its small diameter, the angular resolution is lower than that one can now achieved from the ground with adaptive optics, and time allocated to planetary science is limited. We have successfully used adaptive optics on a 4-m class telescope to obtain 0.1" resolution images of solar system objects in the far red and near infrared (0.7-2.5 microns), aE wavelengths which best discl"lmlnate their spectral signatures. Our efforts have been put into areas of research for which high angular resolution is essential.

  4. Extragalactic Fields Optimized for Adaptive Optics

    DTIC Science & Technology

    2011-03-01

    observatories (including those on Mauna Kea ). Before proceeding with a detailed analysis, it is instructive to note that many positions in the sky likely...4Gemini Observatory , Southern Operations Center, c/o AURA, Casilla 603,La Serena, Chile. sObservatories of the Carnegie Institution of Washington...United States Naval Observatory , 3450 Massachusetts Avenue, NW, Washington, DC 20392-5420. 348 galaxies in these fields require adaptive optics (AO

  5. Phase Contrast Wavefront Sensing for Adaptive Optics

    NASA Technical Reports Server (NTRS)

    Bloemhof, E. E.; Wallace, J. K.; Bloemhof, E. E.

    2004-01-01

    Most ground-based adaptive optics systems use one of a small number of wavefront sensor technologies, notably (for relatively high-order systems) the Shack-Hartmann sensor, which provides local measurements of the phase slope (first-derivative) at a number of regularly-spaced points across the telescope pupil. The curvature sensor, with response proportional to the second derivative of the phase, is also sometimes used, but has undesirable noise propagation properties during wavefront reconstruction as the number of actuators becomes large. It is interesting to consider the use for astronomical adaptive optics of the "phase contrast" technique, originally developed for microscopy by Zemike to allow convenient viewing of phase objects. In this technique, the wavefront sensor provides a direct measurement of the local value of phase in each sub-aperture of the pupil. This approach has some obvious disadvantages compared to Shack-Hartmann wavefront sensing, but has some less obvious but substantial advantages as well. Here we evaluate the relative merits in a practical ground-based adaptive optics system.

  6. Adaptive Reactive Rich Internet Applications

    NASA Astrophysics Data System (ADS)

    Schmidt, Kay-Uwe; Stühmer, Roland; Dörflinger, Jörg; Rahmani, Tirdad; Thomas, Susan; Stojanovic, Ljiljana

    Rich Internet Applications significantly raise the user experience compared with legacy page-based Web applications because of their highly responsive user interfaces. Although this is a tremendous advance, it does not solve the problem of the one-size-fits-all approach1 of current Web applications. So although Rich Internet Applications put the user in a position to interact seamlessly with the Web application, they do not adapt to the context in which the user is currently working. In this paper we address the on-the-fly personalization of Rich Internet Applications. We introduce the concept of ARRIAs: Adaptive Reactive Rich Internet Applications and elaborate on how they are able to adapt to the current working context the user is engaged in. An architecture for the ad hoc adaptation of Rich Internet Applications is presented as well as a holistic framework and tools for the realization of our on-the-fly personalization approach. We divided both the architecture and the framework into two levels: offline/design-time and online/run-time. For design-time we explain how to use ontologies in order to annotate Rich Internet Applications and how to use these annotations for conceptual Web usage mining. Furthermore, we describe how to create client-side executable rules from the semantic data mining results. We present our declarative lightweight rule language tailored to the needs of being executed directly on the client. Because of the event-driven nature of the user interfaces of Rich Internet Applications, we designed a lightweight rule language based on the event-condition-action paradigm.2 At run-time the interactions of a user are tracked directly on the client and in real-time a user model is built up. The user model then acts as input to and is evaluated by our client-side complex event processing and rule engine.

  7. Adaptive optics center of excellence for national security

    NASA Astrophysics Data System (ADS)

    Agrawal, Brij

    2014-06-01

    This paper provides an overview of research at the Adaptive Optics Center of Excellence for national security (AOCoE) at the Naval Postgraduate School (NPS). The Center was established in 2011 with the sponsorship of the Office of Naval Research, National Reconnaissance Office, and Air Force research Laboratory. Research is in two areas: Segmented Mirror telescope (SMT) for imaging satellites and High Energy Laser Beam Control. SMT consists of a 3 meter diameter telescope with six segments and each segment has actuators for surface control and segment alignment. SMT research areas include developing improved techniques for surface control and segment alignment, and reduction in segment vibration by using tuned mass dampers. Research is also performed in adding a deformable mirror into the SMT optical path to correct for residual beam aberration not corrected by the primary mirror actuators. For high energy laser beam control the research areas are acquisition, tracking, and pointing, optical beam jitter control, and application of adaptive optics for correcting beam aberration due to air turbulence. The current focus is on adaptive optics for deep turbulence.

  8. Adaptive optic correction using silicon-based deformable mirros

    NASA Astrophysics Data System (ADS)

    Perreault, Julie A.; Bifano, Thomas G.; Levine, B. Martin

    1999-11-01

    A micromachined deformable mirror ((mu) -DMs) for optical wavefront correction is described. Design and manufacturing approaches for (mu) -DMs are detailed. The (mu) -DM employs a flexible silicon membrane supported by mechanical attachments to an array of electrostatic parallel plate actuators. Devices are fabricated through surface micromachining using polycrystalline silicon thin films. (mu) -DM membranes measuring 2 mm X 2 mm X 2 micrometers , supported by 100 actuators are described. Figures of merit include stroke of 2 micrometers , resolution of 10 nm, and frequency bandwidth DC - 7 kHz. The devices are compact, inexpensive to fabricate, exhibit no hysteresis, and use only a small fraction of the power required for conventional DMs. Performance of an adaptive optics system using a (mu) - DM was characterized in a closed-loop control experiment. Significant reduction in quasi-static wavefront phase error was achieved. Advantages and limitations of (mu) -DMs are described, in relation to conventional adaptive optics systems and to emerging applications of adaptive optics, such as high resolution correction, small aperture systems, and optical communication.

  9. Reflective afocal broadband adaptive optics scanning ophthalmoscope

    PubMed Central

    Dubra, Alfredo; Sulai, Yusufu

    2011-01-01

    A broadband adaptive optics scanning ophthalmoscope (BAOSO) consisting of four afocal telescopes, formed by pairs of off-axis spherical mirrors in a non-planar arrangement, is presented. The non-planar folding of the telescopes is used to simultaneously reduce pupil and image plane astigmatism. The former improves the adaptive optics performance by reducing the root-mean-square (RMS) of the wavefront and the beam wandering due to optical scanning. The latter provides diffraction limited performance over a 3 diopter (D) vergence range. This vergence range allows for the use of any broadband light source(s) in the 450-850 nm wavelength range to simultaneously image any combination of retinal layers. Imaging modalities that could benefit from such a large vergence range are optical coherence tomography (OCT), multi- and hyper-spectral imaging, single- and multi-photon fluorescence. The benefits of the non-planar telescopes in the BAOSO are illustrated by resolving the human foveal photoreceptor mosaic in reflectance using two different superluminescent diodes with 680 and 796 nm peak wavelengths, reaching the eye with a vergence of 0.76 D relative to each other. PMID:21698035

  10. Specialized wavefront sensors for adaptive optics

    NASA Astrophysics Data System (ADS)

    Neal, Daniel R.; Mansell, J. D.; Gruetzner, James K.; Morgan, R.; Warren, Mial E.

    1995-08-01

    The performance of an adaptive optical system is strongly dependent upon correctly measuring the wavefront of the arriving light. The most common wavefront measurement techniques used to date are the shearing interferometer and the Shack-Hartmann sensor. Shack-Hartmann sensors rely on the use of lenslet arrays to sample the aperture appropriately. These have traditionally been constructed using MLM or step and repeat technology, and more recently with binary optics technology. Diffractive optics fabrication methodology can be used to remove some of the limitations of the previous technologies and can allow for low-cost production of sophisticated elements. We have investigated several different specialized wavefront sensor configurations using both Shack-Hartmann and shearing interferometer principles. We have taken advantage of the arbitrary nature of these elements to match pupil shapes of detector and telescope aperture and to introduce magnification between the lenslet array and the detector. We have fabricated elements that facilitate matching the sampling to the current atmospheric conditions. The sensors were designed using a far-field diffraction model and a photolithography layout program. They were fabricated using photolithography and RIE etching. Several different designs are presented with some experimental results from a small-scale adaptive optics brass-board.

  11. Hybrid adaptive-optics visual simulator.

    PubMed

    Cánovas, Carmen; Prieto, Pedro M; Manzanera, Silvestre; Mira, Alejandro; Artal, Pablo

    2010-01-15

    We have developed a hybrid adaptive-optics visual simulator (HAOVS), combining two different phase-manipulation technologies: an optically addressed liquid-crystal phase modulator, relatively slow but capable of producing abrupt or discontinuous phase profiles; and a membrane deformable mirror, restricted to smooth profiles but with a temporal response allowing compensation of the eye's aberration fluctuations. As proof of concept, a phase element structured as discontinuous radial sectors was objectively tested as a function of defocus, and a correction loop was closed in a real eye. To further illustrate the capabilities of the device for visual simulation, we recorded extended images of different stimuli through the system by means of an external camera replacing the subject's eye. The HAOVS is specially intended as a tool for developing new ophthalmic optics elements, where it opens the possibility to explore designs with irregularities and/or discontinuities.

  12. Adaptive optics on a shoe string

    NASA Astrophysics Data System (ADS)

    Restaino, Sergio R.; Payne, Don M.

    1998-12-01

    There are two main ways to mitigate the effects of atmospheric turbulence on an imaging system. A post factor approach, where data are opportunely acquired and processed in order to increase the overall resolution attainable by the optical system, speckle imaging is an example of such technique. The other approach is to use an adaptive optics system that will compensate for atmospheric effects before the data are recorded. Of course, the situation is not sharply distinct. Hybrid approaches have been proposed and demonstrated. Other approaches that are a mid-way between the two are also possible. The basic idea of static and dynamic pupil masking will be presented. Experimental results based on point sources and extended objects will be presented. Advantages and limitations of such technique will be discussed. Finally some new ideas involving fiber optics and liquid crystals will be presented.

  13. Overview of Advanced LIGO adaptive optics.

    PubMed

    Brooks, Aidan F; Abbott, Benjamin; Arain, Muzammil A; Ciani, Giacomo; Cole, Ayodele; Grabeel, Greg; Gustafson, Eric; Guido, Chris; Heintze, Matthew; Heptonstall, Alastair; Jacobson, Mindy; Kim, Won; King, Eleanor; Lynch, Alexander; O'Connor, Stephen; Ottaway, David; Mailand, Ken; Mueller, Guido; Munch, Jesper; Sannibale, Virginio; Shao, Zhenhua; Smith, Michael; Veitch, Peter; Vo, Thomas; Vorvick, Cheryl; Willems, Phil

    2016-10-10

    This is an overview of the adaptive optics used in Advanced LIGO (aLIGO), known as the thermal compensation system (TCS). The TCS was designed to minimize thermally induced spatial distortions in the interferometer optical modes and to provide some correction for static curvature errors in the core optics of aLIGO. The TCS is comprised of ring heater actuators, spatially tunable CO2 laser projectors, and Hartmann wavefront sensors. The system meets the requirements of correcting for nominal distortion in aLIGO to a maximum residual error of 5.4 nm rms, weighted across the laser beam, for up to 125 W of laser input power into the interferometer.

  14. Curvature adaptive optics and low light imaging

    NASA Astrophysics Data System (ADS)

    Ftaclas, C.; Chun, M.; Kuhn, J.; Ritter, J.

    We review the basic approach of curvature adaptive optics (AO) and show how its many advantages arise. A curvature wave front sensor (WFS) measures exactly what a curvature deformable mirror (DM) generates. This leads to the computational and operational simplicity of a nearly diagonal control matrix. The DM automatically reconstructs the wave front based on WFS curvature measurements. Thus, there is no formal wave front reconstruction. This poses an interesting challenge to post-processing of AO images. Physical continuity of the DM and the reconstruction of phase from wave front curvature data assure that each actuated region of the DM corrects local phase, tip-tilt and focus. This gain in per-channel correction efficiency, combined with the need for only one pixel per channel detector reads in the WFS allows the use of photon counting detectors for wave front sensing. We note that the use of photon counting detectors implies penalty-free combination of correction channels either in the WFS or on the DM. This effectively decouples bright and faint source performance in that one no longer predicts the other. The application of curvature AO to the low light moving target detection problem, and explore the resulting challenges to components and control systems. Rapidly moving targets impose high-speed operation posing new requirements unique to curvature components. On the plus side, curvature wave front sensors, unlike their Shack-Hartmann counterparts, are tunable for optimum sensitivity to seeing and we are examining autonomous optimization of the WFS to respond to rapid changes in seeing.

  15. Smart adaptive optic systems using spatial light modulators.

    PubMed

    Clark, N; Banish, M; Ranganath, H S

    1999-01-01

    Many factors contribute to the aberrations induced in an optical system. Atmospheric turbulence between the object and the imaging system, physical or thermal perturbations in optical elements degrade the system's point spread function, and misaligned optics are the primary sources of aberrations that affect image quality. The design of a nonconventional real-time adaptive optic system using a micro-mirror device for wavefront correction is presented. The unconventional compensated imaging system presented offers advantages in speed, cost, power consumption, and weight. A pulsed-coupled neural network is used to as a preprocessor to enhance the performance of the wavefront sensor for low-light applications. Modeling results that characterize the system performance are presented.

  16. Adaptive optics scanning ophthalmoscopy with annular pupils.

    PubMed

    Sulai, Yusufu N; Dubra, Alfredo

    2012-07-01

    Annular apodization of the illumination and/or imaging pupils of an adaptive optics scanning light ophthalmoscope (AOSLO) for improving transverse resolution was evaluated using three different normalized inner radii (0.26, 0.39 and 0.52). In vivo imaging of the human photoreceptor mosaic at 0.5 and 10° from fixation indicates that the use of an annular illumination pupil and a circular imaging pupil provides the most benefit of all configurations when using a one Airy disk diameter pinhole, in agreement with the paraxial confocal microscopy theory. Annular illumination pupils with 0.26 and 0.39 normalized inner radii performed best in terms of the narrowing of the autocorrelation central lobe (between 7 and 12%), and the increase in manual and automated photoreceptor counts (8 to 20% more cones and 11 to 29% more rods). It was observed that the use of annular pupils with large inner radii can result in multi-modal cone photoreceptor intensity profiles. The effect of the annular masks on the average photoreceptor intensity is consistent with the Stiles-Crawford effect (SCE). This indicates that combinations of images of the same photoreceptors with different apodization configurations and/or annular masks can be used to distinguish cones from rods, even when the former have complex multi-modal intensity profiles. In addition to narrowing the point spread function transversally, the use of annular apodizing masks also elongates it axially, a fact that can be used for extending the depth of focus of techniques such as adaptive optics optical coherence tomography (AOOCT). Finally, the positive results from this work suggest that annular pupil apodization could be used in refractive or catadioptric adaptive optics ophthalmoscopes to mitigate undesired back-reflections.

  17. Adaptive optics scanning ophthalmoscopy with annular pupils

    PubMed Central

    Sulai, Yusufu N.; Dubra, Alfredo

    2012-01-01

    Annular apodization of the illumination and/or imaging pupils of an adaptive optics scanning light ophthalmoscope (AOSLO) for improving transverse resolution was evaluated using three different normalized inner radii (0.26, 0.39 and 0.52). In vivo imaging of the human photoreceptor mosaic at 0.5 and 10° from fixation indicates that the use of an annular illumination pupil and a circular imaging pupil provides the most benefit of all configurations when using a one Airy disk diameter pinhole, in agreement with the paraxial confocal microscopy theory. Annular illumination pupils with 0.26 and 0.39 normalized inner radii performed best in terms of the narrowing of the autocorrelation central lobe (between 7 and 12%), and the increase in manual and automated photoreceptor counts (8 to 20% more cones and 11 to 29% more rods). It was observed that the use of annular pupils with large inner radii can result in multi-modal cone photoreceptor intensity profiles. The effect of the annular masks on the average photoreceptor intensity is consistent with the Stiles-Crawford effect (SCE). This indicates that combinations of images of the same photoreceptors with different apodization configurations and/or annular masks can be used to distinguish cones from rods, even when the former have complex multi-modal intensity profiles. In addition to narrowing the point spread function transversally, the use of annular apodizing masks also elongates it axially, a fact that can be used for extending the depth of focus of techniques such as adaptive optics optical coherence tomography (AOOCT). Finally, the positive results from this work suggest that annular pupil apodization could be used in refractive or catadioptric adaptive optics ophthalmoscopes to mitigate undesired back-reflections. PMID:22808435

  18. The Adaptive Optics Summer School Laboratory Activities

    NASA Astrophysics Data System (ADS)

    Ammons, S. M.; Severson, S.; Armstrong, J. D.; Crossfield, I.; Do, T.; Fitzgerald, M.; Harrington, D.; Hickenbotham, A.; Hunter, J.; Johnson, J.; Johnson, L.; Li, K.; Lu, J.; Maness, H.; Morzinski, K.; Norton, A.; Putnam, N.; Roorda, A.; Rossi, E.; Yelda, S.

    2010-12-01

    Adaptive Optics (AO) is a new and rapidly expanding field of instrumentation, yet astronomers, vision scientists, and general AO practitioners are largely unfamiliar with the root technologies crucial to AO systems. The AO Summer School (AOSS), sponsored by the Center for Adaptive Optics, is a week-long course for training graduate students and postdoctoral researchers in the underlying theory, design, and use of AO systems. AOSS participants include astronomers who expect to utilize AO data, vision scientists who will use AO instruments to conduct research, opticians and engineers who design AO systems, and users of high-bandwidth laser communication systems. In this article we describe new AOSS laboratory sessions implemented in 2006-2009 for nearly 250 students. The activity goals include boosting familiarity with AO technologies, reinforcing knowledge of optical alignment techniques and the design of optical systems, and encouraging inquiry into critical scientific questions in vision science using AO systems as a research tool. The activities are divided into three stations: Vision Science, Fourier Optics, and the AO Demonstrator. We briefly overview these activities, which are described fully in other articles in these conference proceedings (Putnam et al., Do et al., and Harrington et al., respectively). We devote attention to the unique challenges encountered in the design of these activities, including the marriage of inquiry-like investigation techniques with complex content and the need to tune depth to a graduate- and PhD-level audience. According to before-after surveys conducted in 2008, the vast majority of participants found that all activities were valuable to their careers, although direct experience with integrated, functional AO systems was particularly beneficial.

  19. Imaging Radio Galaxies with Adaptive Optics

    NASA Astrophysics Data System (ADS)

    de Vries, W. H.; van Breugel, W. J. M.; Quirrenbach, A.; Roberts, J.; Fidkowski, K.

    2000-12-01

    We present 42 milli-arcsecond resolution Adaptive Optics near-infrared images of 3C 452 and 3C 294, two powerful radio galaxies at z=0.081 and z=1.79 respectively, obtained with the NIRSPEC/SCAM+AO instrument on the Keck telescope. The observations provide unprecedented morphological detail of radio galaxy components like nuclear dust-lanes, off-centered or binary nuclei, and merger induced starforming structures; all of which are key features in understanding galaxy formation and the onset of powerful radio emission. Complementary optical HST imaging data are used to construct high resolution color images, which, for the first time, have matching optical and near-IR resolutions. Based on these maps, the extra-nuclear structural morphologies and compositions of both galaxies are discussed. Furthermore, detailed brightness profile analysis of 3C 452 allows a direct comparison to a large literature sample of nearby ellipticals, all of which have been observed in the optical and near-IR by HST. Both the imaging data and the profile information on 3C 452 are consistent with it being a relative diminutive and well-evolved elliptical, in stark contrast to 3C 294 which seems to be in its initial formation throes with an active AGN off-centered from the main body of the galaxy. These results are discussed further within the framework of radio galaxy triggering and the formation of massive ellipticals. The work of WdV and WvB was performed under the auspices of the U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48. The work at UCSD has been supported by the NSF Science and Technology Center for Adaptive Optics, under agreement No. AST-98-76783.

  20. The CHARA Array Adaptive Optics Program

    NASA Astrophysics Data System (ADS)

    Ten Brummelaar, Theo; Che, Xiao; McAlister, Harold A.; Ireland, Michael; Monnier, John D.; Mourard, Denis; Ridgway, Stephen T.; sturmann, judit; Sturmann, Laszlo; Turner, Nils H.; Tuthill, Peter

    2016-01-01

    The CHARA array is an optical/near infrared interferometer consisting of six 1-meter diameter telescopes the longest baseline of which is 331 meters. With sub-millisecond angular resolution, the CHARA array is able to spatially resolve nearby stellar systems to reveal the detailed structures. To improve the sensitivity and scientific throughput, the CHARA array was funded by NSF-ATI in 2011, and by NSF-MRI in 2015, for an upgrade of adaptive optics (AO) systems to all six telescopes. The initial grant covers Phase I of the adaptive optics system, which includes an on-telescope Wavefront Sensor and non-common-path (NCP) error correction. The WFS use a fairly standard Shack-Hartman design and will initially close the tip tilt servo and log wavefront errors for use in data reduction and calibration. The second grant provides the funding for deformable mirrors for each telescope which will be used closed loop to remove atmospheric aberrations from the beams. There are then over twenty reflections after the WFS at the telescopes that bring the light several hundred meters into the beam combining laboratory. Some of these, including the delay line and beam reducing optics, are powered elements, and some of them, in particular the delay lines and telescope Coude optics, are continually moving. This means that the NCP problems in an interferometer are much greater than those found in more standard telescope systems. A second, slow AO system is required in the laboratory to correct for these NCP errors. We will breifly describe the AO system, and it's current status, as well as discuss the new science enabled by the system with a focus on our YSO program.

  1. Adaptive optics without altering visual perception

    PubMed Central

    DE, Koenig; NW, Hart; HJ, Hofer

    2014-01-01

    Adaptive optics combined with visual psychophysics creates the potential to study the relationship between visual function and the retina at the cellular scale. This potential is hampered, however, by visual interference from the wavefront-sensing beacon used during correction. For example, we have previously shown that even a dim, visible beacon can alter stimulus perception (Hofer, H. J., Blaschke, J., Patolia, J., & Koenig, D. E. (2012). Fixation light hue bias revisited: Implications for using adaptive optics to study color vision. Vision Research, 56, 49-56). Here we describe a simple strategy employing a longer wavelength (980nm) beacon that, in conjunction with appropriate restriction on timing and placement, allowed us to perform psychophysics when dark adapted without altering visual perception. The method was verified by comparing detection and color appearance of foveally presented small spot stimuli with and without the wavefront beacon present in 5 subjects. As an important caution, we found that significant perceptual interference can occur even with a subliminal beacon when additional measures are not taken to limit exposure. Consequently, the lack of perceptual interference should be verified for a given system, and not assumed based on invisibility of the beacon. PMID:24607992

  2. Adaptive Optics Imaging in Laser Pointer Maculopathy.

    PubMed

    Sheyman, Alan T; Nesper, Peter L; Fawzi, Amani A; Jampol, Lee M

    2016-08-01

    The authors report multimodal imaging including adaptive optics scanning laser ophthalmoscopy (AOSLO) (Apaeros retinal image system AOSLO prototype; Boston Micromachines Corporation, Boston, MA) in a case of previously diagnosed unilateral acute idiopathic maculopathy (UAIM) that demonstrated features of laser pointer maculopathy. The authors also show the adaptive optics images of a laser pointer maculopathy case previously reported. A 15-year-old girl was referred for the evaluation of a maculopathy suspected to be UAIM. The authors reviewed the patient's history and obtained fluorescein angiography, autofluorescence, optical coherence tomography, infrared reflectance, and AOSLO. The time course of disease and clinical examination did not fit with UAIM, but the linear pattern of lesions was suspicious for self-inflicted laser pointer injury. This was confirmed on subsequent questioning of the patient. The presence of linear lesions in the macula that are best highlighted with multimodal imaging techniques should alert the physician to the possibility of laser pointer injury. AOSLO further characterizes photoreceptor damage in this condition. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:782-785.]. Copyright 2016, SLACK Incorporated.

  3. The ESO Adaptive Optics Facility under Test

    NASA Astrophysics Data System (ADS)

    Arsenault, Robin; Madec, Pierre-Yves; Paufique, Jerome; La Penna, Paolo; Stroebele, Stefan; Vernet, Elise; Pirard, Jean-François; Hackenberg, Wolfgang; Kuntschner, Harald; Kolb, Johann; Muller, Nicolas; Le Louarn, Miska; Amico, Paola; Hubin, Norbert; Lizon, Jean-Louis; Ridings, Rob; Abad, Jose; Fischer, Gert; Heinz, Volker; Kiekebusch, Mario; Argomedo, Javier; Conzelmann, Ralf; Tordo, Sebastien; Donaldson, Rob; Soenke, Christian; Duhoux, Philippe; Fedrigo, Enrico; Delabre, Bernard; Jost, Andrea; Duchateau, Michel; Downing, Mark; Moreno, Javier; Manescau, Antonio; Bonaccini Calia, Domenico; Quattri, Marco; Dupuy, Christophe; Guidolin, Ivan; Comin, Mauro; Guzman, Ronald; Buzzoni, Bernard; Quentin, Jutta; Lewis, Steffan; Jolley, Paul; Kraus, Max; Pfrommer, Thomas; Garcia-Rissmann, Aurea; Biasi, Roberto; Gallieni, Daniele; Stuik, Remko

    2013-12-01

    The Adaptive Optics Facility project has received most of its subsystems in Garching and the ESO Integration Hall has become the central operation location for the next phase of the project. The main test bench ASSIST and the 2nd Generation M2-Unit (hosting the Deformable Secondary Mirror) have been granted acceptance late 2012. The DSM will now undergo a series of tests on ASSIST to qualify its optical performance which launches the System Test Phase of the AOF. The tests will validate the AO modules operation with the DSM: first the GRAAL adaptive optics module for Hawk-I in natural guide star AO mode on-axis and then its Ground Layer AO mode. This will be followed by the GALACSI (for MUSE) Wide-Field-Mode (GLAO) and then the more challenging Narrow-Field-Mode (LTAO). We will report on the status of the subsystems at the time of the conference but also on the performance of the delivered ASSIST test bench, the DSM and the 20 Watt Sodium fiber Laser pre-production unit which has validated all specifications before final manufacturing of the serial units. We will also present some considerations and tools to ensure an efficient operation of the Facility in Paranal.

  4. Multifocal multiphoton microscopy with adaptive optical correction

    NASA Astrophysics Data System (ADS)

    Coelho, Simao; Poland, Simon; Krstajic, Nikola; Li, David; Monypenny, James; Walker, Richard; Tyndall, David; Ng, Tony; Henderson, Robert; Ameer-Beg, Simon

    2013-02-01

    Fluorescence lifetime imaging microscopy (FLIM) is a well established approach for measuring dynamic signalling events inside living cells, including detection of protein-protein interactions. The improvement in optical penetration of infrared light compared with linear excitation due to Rayleigh scattering and low absorption have provided imaging depths of up to 1mm in brain tissue but significant image degradation occurs as samples distort (aberrate) the infrared excitation beam. Multiphoton time-correlated single photon counting (TCSPC) FLIM is a method for obtaining functional, high resolution images of biological structures. In order to achieve good statistical accuracy TCSPC typically requires long acquisition times. We report the development of a multifocal multiphoton microscope (MMM), titled MegaFLI. Beam parallelization performed via a 3D Gerchberg-Saxton (GS) algorithm using a Spatial Light Modulator (SLM), increases TCSPC count rate proportional to the number of beamlets produced. A weighted 3D GS algorithm is employed to improve homogeneity. An added benefit is the implementation of flexible and adaptive optical correction. Adaptive optics performed by means of Zernike polynomials are used to correct for system induced aberrations. Here we present results with significant improvement in throughput obtained using a novel complementary metal-oxide-semiconductor (CMOS) 1024 pixel single-photon avalanche diode (SPAD) array, opening the way to truly high-throughput FLIM.

  5. In vivo cellular visualization of the human retina using optical coherence tomography and adaptive optics

    SciTech Connect

    Olivier, S S; Jones, S M; Chen, D C; Zawadzki, R J; Choi, S S; Laut, S P; Werner, J S

    2006-01-05

    Optical coherence tomography (OCT) sees the human retina sharply with adaptive optics. In vivo cellular visualization of the human retina at micrometer-scale resolution is possible by enhancing Fourier-domain optical-coherence tomography with adaptive optics, which compensate for the eye's optical aberrations.

  6. Wave optics propagation code for multiconjugate adaptive optics

    NASA Astrophysics Data System (ADS)

    Ellerbroek, Brent L.; Cochran, Gregory

    2002-02-01

    We describe the purpose, theory, implementation and sample results of a wave optics propagation simulation developed to study multi-conjugate adaptive optics (MCAQ) for 4-10m class telescopes. This code was more specifically developed to assess the impact of diffraction effects and a variety of implementation error sources upon the performance of the Gemini-South MCAO system. These errors include: Hartmann sensing with extended and elongated laser guide stars, optical propagation effects through the optics and atmosphere, laser guide star (LGS) projection through the atmosphere, deformable mirror (DM) and wave front sensor (WFS) misregistration, and calibration for non-common path errors. The code may be run in either a wave optics or geometric propagation mode to allow the code to be anchored against linear analytical models and to explicitly evaluate the impact of diffraction effects. The code is written in MATLAB, and complete simulations of the Gemini-South MCAO design (including 3 deformable mirrors with 769 actuators, 5 LGS WFS with 1020 subapertures, 3 tip/tilt natural guide star (NGS) WFS, and 50 meter phase screens with 1/32nd meter resolution) are possible using a Pentium III but require 1 to 6 days. Sample results are presented for Gemini-South MCAO as well as simpler AO systems. Several possibilities for parallelizing the code for faster execution and the modeling of extremely large telescopes (ELT's) are discussed.

  7. Progress with the lick adaptive optics system

    SciTech Connect

    Gavel, D T; Olivier, S S; Bauman, B; Max, C E; Macintosh, B

    2000-03-01

    Progress and results of observations with the Lick Observatory Laser Guide Star Adaptive Optics System are presented. This system is optimized for diffraction-limited imaging in the near infrared, 1-2 micron wavelength bands. We describe our development efforts in a number of component areas including, a redesign of the optical bench layout, the commissioning of a new infrared science camera, and improvements to the software and user interface. There is also an ongoing effort to characterize the system performance with both natural and laser guide stars and to fold this data into a refined system model. Such a model can be used to help plan future observations, for example, predicting the point-spread function as a function of seeing and guide star magnitude.

  8. Progress with the Lick adaptive optics system

    NASA Astrophysics Data System (ADS)

    Gavel, Donald T.; Olivier, Scot S.; Bauman, Brian J.; Max, Claire E.; Macintosh, Bruce A.

    2000-07-01

    Progress and results of observations with the Lick Observatory Laser Guide Star Adaptive Optics System are presented. This system is optimized for diffraction-limited imaging in the near infrared, 1 - 2 micron wavelength bands. We describe our development efforts in a number of component areas including, a redesign of the optical bench layout, the commissioning of a new infrared science camera, and improvements to the software and user interface. There is also an ongoing effort to characterize the system performance with both natural and laser guide stars and to fold this data into a refined system model. Such a model can be used to help plan future observations, for example, predicting the point-spread function as a function of seeing and guide star magnitude.

  9. Characterization of Adaptive Optics at Keck Observatory

    SciTech Connect

    van Dam, M A; Macintosh, B A

    2003-07-24

    In this paper, the adaptive optics (AO) system at Keck Observatory is characterized. The AO system is described in detail. The physical parameters of the lenslets, CCD and deformable mirror, the calibration procedures and the signal processing algorithms are explained. Results of sky performance tests are presented: the AO system is shown to deliver images with an average Strehl ratio of up to 0.37 at 1.59 {micro}m using a bright guide star. An error budget that is consistent with the observed image quality is presented.

  10. Adaptive Holographic Fiber-Optic Interferometer

    NASA Astrophysics Data System (ADS)

    Kozhevnikov, Nikolai M.; Lipovskaya, Margarita J.

    1990-04-01

    Interaction of phase-modulated light beams in photorefractive local inertial responce media was analysed. Interaction of this type allows to registrate phase-modulated signals adaptively under low frequency phase disturbtion. The experiments on multimode fiber-optic interferometer with demodulation element based on photorefractive bacteriorhodopsin-doped polimer film are described. As the writing of dynamic phase hologram is an inertial process the signal fluctuations with the frequencies up to 100 Hz can be canceled. The hologram efficiencies are enough to registrate high frequency phase shifts ~10-4 radn.

  11. Computational adaptive optics for broadband optical interferometric tomography of biological tissue

    NASA Astrophysics Data System (ADS)

    Boppart, Stephen A.

    2015-03-01

    High-resolution real-time tomography of biological tissues is important for many areas of biological investigations and medical applications. Cellular level optical tomography, however, has been challenging because of the compromise between transverse imaging resolution and depth-of-field, the system and sample aberrations that may be present, and the low imaging sensitivity deep in scattering tissues. The use of computed optical imaging techniques has the potential to address several of these long-standing limitations and challenges. Two related techniques are interferometric synthetic aperture microscopy (ISAM) and computational adaptive optics (CAO). Through three-dimensional Fourierdomain resampling, in combination with high-speed OCT, ISAM can be used to achieve high-resolution in vivo tomography with enhanced depth sensitivity over a depth-of-field extended by more than an order-of-magnitude, in realtime. Subsequently, aberration correction with CAO can be performed in a tomogram, rather than to the optical beam of a broadband optical interferometry system. Based on principles of Fourier optics, aberration correction with CAO is performed on a virtual pupil using Zernike polynomials, offering the potential to augment or even replace the more complicated and expensive adaptive optics hardware with algorithms implemented on a standard desktop computer. Interferometric tomographic reconstructions are characterized with tissue phantoms containing sub-resolution scattering particles, and in both ex vivo and in vivo biological tissue. This review will collectively establish the foundation for high-speed volumetric cellular-level optical interferometric tomography in living tissues.

  12. Optical Design for Extremely Large Telescope Adaptive Optics Systems

    SciTech Connect

    Bauman, Brian J.

    2003-01-01

    Designing an adaptive optics (AO) system for extremely large telescopes (ELT's) will present new optical engineering challenges. Several of these challenges are addressed in this work, including first-order design of multi-conjugate adaptive optics (MCAO) systems, pyramid wavefront sensors (PWFS's), and laser guide star (LGS) spot elongation. MCAO systems need to be designed in consideration of various constraints, including deformable mirror size and correction height. The y,{bar y} method of first-order optical design is a graphical technique that uses a plot with marginal and chief ray heights as coordinates; the optical system is represented as a segmented line. This method is shown to be a powerful tool in designing MCAO systems. From these analyses, important conclusions about configurations are derived. PWFS's, which offer an alternative to Shack-Hartmann (SH) wavefront sensors (WFS's), are envisioned as the workhorse of layer-oriented adaptive optics. Current approaches use a 4-faceted glass pyramid to create a WFS analogous to a quad-cell SH WFS. PWFS's and SH WFS's are compared and some newly-considered similarities and PWFS advantages are presented. Techniques to extend PWFS's are offered: First, PWFS's can be extended to more pixels in the image by tiling pyramids contiguously. Second, pyramids, which are difficult to manufacture, can be replaced by less expensive lenslet arrays. An approach is outlined to convert existing SH WFS's to PWFS's for easy evaluation of PWFS's. Also, a demonstration of PWFS's in sensing varying amounts of an aberration is presented. For ELT's, the finite altitude and finite thickness of LGS's means that the LGS will appear elongated from the viewpoint of subapertures not directly under the telescope. Two techniques for dealing with LGS spot elongation in SH WFS's are presented. One method assumes that the laser will be pulsed and uses a segmented micro-electromechanical system (MEMS) to track the LGS light subaperture by

  13. Adaptive Quality of Transmission Control in Elastic Optical Network

    NASA Astrophysics Data System (ADS)

    Cai, Xinran

    Optical fiber communication is becoming increasingly important due to the burgeoning demand in the internet capacity. However, traditional wavelength division multiplexing (WDM) technique fails to address such demand because of its inefficient spectral utilization. As a result, elastic optical networking (EON) has been under extensive investigation recently. Such network allows sub-wavelength and super-wavelength channel accommodation, and mitigates the stranded bandwidth problem in the WDM network. In addition, elastic optical network is also able to dynamically allocate the spectral resources of the network based on channel conditions and impairments, and adaptively control the quality of transmission of a channel. This application requires two aspects to be investigated: an efficient optical performance monitoring scheme and networking control and management algorithms to reconfigure the network in a dynamic fashion. This thesis focuses on the two aspects discussed above about adaptive QoT control. We demonstrated a supervisory channel method for optical signal to noise ratio (OSNR) and chromatic dispersion (CD) monitoring. In addition, our proof-of-principle testbed experiments show successful impairment aware reconfiguration of the network with modulation format switching (MFS) only and MFS combined with lightpath rerouting (LR) for hundred-GHz QPSK superchannels undergoing time-varying OSNR impairment.

  14. Performance of a compact adaptive-optics system.

    PubMed

    Frazier, Benjamin West; Smith, Mark; Tyson, Robert K

    2004-08-01

    The design of an adaptive-optics system for correction of a beam propagating through high-speed, unpredictable optical turbulence required the use of a robust controller rather than a conventional least-squares controller. We describe the 37-channel, 50-Hz adaptive-optical system and its performance (lambda/75 rms).

  15. An adaptive interferometer for optical testing .

    NASA Astrophysics Data System (ADS)

    Pariani, G.; Colella, L.; Bertarelli, C.; Aliverti, M.; Riva, M.; Bianco, A.

    Interferometry is a well-established technique to test optical elements. However, its use is challenging in the case of free-form and aspheric elements, due to the lack of the reference optics. The proposed idea concerns the development of a versatile interferometer, where its reference arm is equipped with a reprogrammable Computer Generated Hologram. This principle takes advantage from our study on photochromic materials for optical applications, which shows a strong and reversible modulation of transparency in the visible region. The encoding of the desired hologram can be done off-line, or directly into the interferometer, and different patterns may be realized sequentially after the erasing of the previous hologram. We report on the present state of the research and on the future perspectives. skip=5pt

  16. Extreme Adaptive Optics Planet Imager: XAOPI

    SciTech Connect

    Macintosh, B A; Graham, J; Poyneer, L; Sommargren, G; Wilhelmsen, J; Gavel, D; Jones, S; Kalas, P; Lloyd, J; Makidon, R; Olivier, S; Palmer, D; Patience, J; Perrin, M; Severson, S; Sheinis, A; Sivaramakrishnan, A; Troy, M; Wallace, K

    2003-09-17

    Ground based adaptive optics is a potentially powerful technique for direct imaging detection of extrasolar planets. Turbulence in the Earth's atmosphere imposes some fundamental limits, but the large size of ground-based telescopes compared to spacecraft can work to mitigate this. We are carrying out a design study for a dedicated ultra-high-contrast system, the eXtreme Adaptive Optics Planet Imager (XAOPI), which could be deployed on an 8-10m telescope in 2007. With a 4096-actuator MEMS deformable mirror it should achieve Strehl >0.9 in the near-IR. Using an innovative spatially filtered wavefront sensor, the system will be optimized to control scattered light over a large radius and suppress artifacts caused by static errors. We predict that it will achieve contrast levels of 10{sup 7}-10{sup 8} at angular separations of 0.2-0.8 inches around a large sample of stars (R<7-10), sufficient to detect Jupiter-like planets through their near-IR emission over a wide range of ages and masses. We are constructing a high-contrast AO testbed to verify key concepts of our system, and present preliminary results here, showing an RMS wavefront error of <1.3 nm with a flat mirror.

  17. Performance of adaptive optics at Lick Observatory

    SciTech Connect

    Olivier, S.S.; An, J.; Avicola, K.

    1994-03-01

    A prototype adaptive optics system has been developed at Lawrence Livermore National Laboratory (LLNL) for use at Lick Observatory. This system is based on an ITEX 69-actuator continuous-surface deformable mirror, a Kodak fast-framing intensified CCD camera, and a Mercury VME board containing four Intel i860 processors. The system has been tested using natural reference stars on the 40-inch Nickel telescope at Lick Observatory yielding up to a factor of 10 increase in image peak intensity and a factor of 6 reduction in image full width at half maximum (FWHM). These results are consistent with theoretical expectations. In order to improve performance, the intensified CCD camera will be replaced by a high-quantum-efficiency low-noise fast CCD camera built for LLNL by Adaptive Optics Associates using a chip developed by Lincoln Laboratory, and the 69-actuator deformable mirror will be replaced by a 127-actuator deformable mirror developed at LLNL. With these upgrades, the system should perform well in median seeing conditions on the 120-inch Shane telescope for observing wavelengths longer than {approximately}1 {mu}m and using natural reference stars brighter than m{sub R} {approximately} 10 or using the laser currently being developed at LLNL for use at Lick Observatory to generate a sodium-layer reference star.

  18. Optical design of the adaptive optics laser guide star system

    SciTech Connect

    Bissinger, H.

    1994-11-15

    The design of an adaptive optics package for the 3 meter Lick telescope is presented. This instrument package includes a 69 actuator deformable mirror and a Hartmann type wavefront sensor operating in the visible wavelength; a quadrant detector for the tip-tile sensor and a tip-tilt mirror to stabilize atmospheric first order tip-tile errors. A high speed computer drives the deformable mirror to achieve near diffraction limited imagery. The different optical components and their individual design constraints are described. motorized stages and diagnostics tools are used to operate and maintain alignment throughout observation time from a remote control room. The expected performance are summarized and actual results of astronomical sources are presented.

  19. Daytime adaptive optics for deep space optical communications

    NASA Technical Reports Server (NTRS)

    Wilson, Keith; Troy, M.; Srinivasan, M.; Platt, B.; Vilnrotter, V.; Wright, M.; Garkanian, V.; Hemmati, H.

    2003-01-01

    The deep space optical communications subsystem offers a higher bandwidth communications link in smaller size, lower mass, and lower power consumption subsystem than does RF. To demonstrate the benefit of this technology to deep space communications NASA plans to launch an optical telecommunications package on the 2009 Mars Telecommunications orbiter spacecraft. Current performance goals are 30-Mbps from opposition, and 1-Mbps near conjunction (-3 degrees Sun-Earth-Probe angle). Yet, near conjunction the background noise from the day sky will degrade the performance of the optical link. Spectral and spatial filtering and higher modulation formats can mitigate the effects of background sky. Narrowband spectral filters can result in loss of link margin, and higher modulation formats require higher transmitted peak powers. In contrast, spatial filtering at the receiver has the potential of being lossless while providing the required sky background rejection. Adaptive optics techniques can correct wave front aberrations caused by atmospheric turbulence and enable near-diffraction-limited performance of the receiving telescope. Such performance facilitates spatial filtering, and allows the receiver field-of-view and hence the noise from the sky background to be reduced.

  20. Daytime adaptive optics for deep space optical communications

    NASA Technical Reports Server (NTRS)

    Wilson, Keith; Troy, M.; Srinivasan, M.; Platt, B.; Vilnrotter, V.; Wright, M.; Garkanian, V.; Hemmati, H.

    2003-01-01

    The deep space optical communications subsystem offers a higher bandwidth communications link in smaller size, lower mass, and lower power consumption subsystem than does RF. To demonstrate the benefit of this technology to deep space communications NASA plans to launch an optical telecommunications package on the 2009 Mars Telecommunications orbiter spacecraft. Current performance goals are 30-Mbps from opposition, and 1-Mbps near conjunction (-3 degrees Sun-Earth-Probe angle). Yet, near conjunction the background noise from the day sky will degrade the performance of the optical link. Spectral and spatial filtering and higher modulation formats can mitigate the effects of background sky. Narrowband spectral filters can result in loss of link margin, and higher modulation formats require higher transmitted peak powers. In contrast, spatial filtering at the receiver has the potential of being lossless while providing the required sky background rejection. Adaptive optics techniques can correct wave front aberrations caused by atmospheric turbulence and enable near-diffraction-limited performance of the receiving telescope. Such performance facilitates spatial filtering, and allows the receiver field-of-view and hence the noise from the sky background to be reduced.

  1. Manufacturing of the ESO adaptive optics facility

    NASA Astrophysics Data System (ADS)

    Arsenault, R.,; Madec, P.-Y.; Hubin, N.; Stroebele, S.; Paufique, J.; Vernet, E.; Hackenberg, W.; Pirard, J.-F.; Jochum, L.; Glindemann, A.; Jost, A.; Conzelmann, R.; Kiekebusch, M.; Tordo, S.; Lizon, J.-L.; Donaldson, R.; Fedrigo, E.; Soenke, C.; Duchateau, M.; Bruton, A.; Delabre, B.; Downing, M.; Reyes, J.; Kolb, J.; Bechet, C.; Lelouarn, M.; Bonaccini Calia, D.; Quattri, M.; Guidolin, I.; Buzzoni, B.; Dupuy, C.; Guzman, R.; Comin, M.; Silber, A.; Quentin, J.; La Penna, P.; Manescau, A.; Jolley, P.; Heinz, V.; Duhoux, P.; Argomedo, J.; Gallieni, D.; Lazzarini, P.; Biasi, R.; Andrighettoni, M.; Angerer, G.; Pescoller, D.; Stuik, R.,; Deep, A.

    2010-07-01

    The ESO Adaptive Optics Facility (AOF) consists in an evolution of one of the ESO VLT unit telescopes to a laser driven adaptive telescope with a deformable mirror in its optical train, in this case the secondary 1.1m mirror, and four Laser Guide Stars (LGSs). This evolution implements many challenging technologies like the Deformable Secondary Mirror (DSM) including a thin shell mirror (1.1 m diameter and 2mm thin), the high power Na lasers (20W), the low Read-Out Noise (RON) WaveFront Sensor (WFS) camera (< 1e-) and SPARTA the new generation of Real Time Computers (RTC) for adaptive control. It also faces many problematic similar to any Extremely Large Telescope (ELT) and as such, will validate many technologies and solutions needed for the European ELT (E-ELT) 42m telescope. The AOF will offer a very large (7 arcmin) Field Of View (FOV) GLAO correction in J, H and K bands (GRAAL+Hawk-I), a visible integral field spectrograph with a 1 arcmin GLAO corrected FOV (GALACSI-MUSE WFM) and finally a LTAO 7.5" FOV (GALACSI-MUSE NFM). Most systems of the AOF have completed final design and are in manufacturing phase. Specific activities are linked to the modification of the 8m telescope in order to accommodate the new DSM and the 4 LGS Units assembled on its Center-Piece. A one year test period in Europe is planned to test and validate all modes and their performance followed by a commissioning phase in Paranal scheduled for 2014.

  2. Object-oriented Matlab adaptive optics toolbox

    NASA Astrophysics Data System (ADS)

    Conan, R.; Correia, C.

    2014-08-01

    Object-Oriented Matlab Adaptive Optics (OOMAO) is a Matlab toolbox dedicated to Adaptive Optics (AO) systems. OOMAO is based on a small set of classes representing the source, atmosphere, telescope, wavefront sensor, Deformable Mirror (DM) and an imager of an AO system. This simple set of classes allows simulating Natural Guide Star (NGS) and Laser Guide Star (LGS) Single Conjugate AO (SCAO) and tomography AO systems on telescopes up to the size of the Extremely Large Telescopes (ELT). The discrete phase screens that make the atmosphere model can be of infinite size, useful for modeling system performance on large time scales. OOMAO comes with its own parametric influence function model to emulate different types of DMs. The cone effect, altitude thickness and intensity profile of LGSs are also reproduced. Both modal and zonal modeling approach are implemented. OOMAO has also an extensive library of theoretical expressions to evaluate the statistical properties of turbulence wavefronts. The main design characteristics of the OOMAO toolbox are object-oriented modularity, vectorized code and transparent parallel computing. OOMAO has been used to simulate and to design the Multi-Object AO prototype Raven at the Subaru telescope and the Laser Tomography AO system of the Giant Magellan Telescope. In this paper, a Laser Tomography AO system on an ELT is simulated with OOMAO. In the first part, we set-up the class parameters and we link the instantiated objects to create the source optical path. Then we build the tomographic reconstructor and write the script for the pseudo-open-loop controller.

  3. Scientific programs in adaptive optics: an overview and commentary

    NASA Astrophysics Data System (ADS)

    Ridgway, Stephen T.

    1998-09-01

    Following extensive development effort, approximately a dozen adaptive optics facilities are now available for research in astronomy, and a similar number is nearing competition or in advanced planning. The scientific productivity, measured by research papers, is rapidly increasing. From a survey of published research and a review of research provisionally discuss the contribution of natural guide star adaptive optics to astronomy. The most active research topics for adaptive optics astronomy have been in solar system studies and in the observation of young stars and star forming regions. The benefit of adaptive optics most prominently exercised in these observations has been high resolution imagery, and the most common area of concern is the point spread function. The scientific success supports the position that adaptive optics will son be required for large telescopes to remain competitive in certain research areas. At the same time, most areas of astronomy research remain untouched by adaptive optics techniques.

  4. Foundry Microfabrication of Deformable Mirrors for Adaptive Optics

    DTIC Science & Technology

    1998-04-28

    FOUNDRY MICROFABRICATION OF DEFORMABLE MIRRORS FOR ADAPTIVE OPTICS DISSERTATION William D. Cowan, Major, USAF AFIT/DS/ENG/98-07 The views...Adaptive Optics William D. Cowan, MSEE, BSEE Major, USAF Approved: ^rVC/C-^* •ŕ . ; "Chain ^_ Victor M. Bright, Ph.D., Committee’Ch irman AFIT...DEFORMABLE MIRRORS FOR ADAPTIVE OPTICS DISSERTATION Presented to the Faculty of the Graduate School of Engineering of the Air Force Institute of

  5. Adaptive optics with pupil tracking for high resolution retinal imaging.

    PubMed

    Sahin, Betul; Lamory, Barbara; Levecq, Xavier; Harms, Fabrice; Dainty, Chris

    2012-02-01

    Adaptive optics, when integrated into retinal imaging systems, compensates for rapidly changing ocular aberrations in real time and results in improved high resolution images that reveal the photoreceptor mosaic. Imaging the retina at high resolution has numerous potential medical applications, and yet for the development of commercial products that can be used in the clinic, the complexity and high cost of the present research systems have to be addressed. We present a new method to control the deformable mirror in real time based on pupil tracking measurements which uses the default camera for the alignment of the eye in the retinal imaging system and requires no extra cost or hardware. We also present the first experiments done with a compact adaptive optics flood illumination fundus camera where it was possible to compensate for the higher order aberrations of a moving model eye and in vivo in real time based on pupil tracking measurements, without the real time contribution of a wavefront sensor. As an outcome of this research, we showed that pupil tracking can be effectively used as a low cost and practical adaptive optics tool for high resolution retinal imaging because eye movements constitute an important part of the ocular wavefront dynamics.

  6. Adaptive optics with pupil tracking for high resolution retinal imaging

    PubMed Central

    Sahin, Betul; Lamory, Barbara; Levecq, Xavier; Harms, Fabrice; Dainty, Chris

    2012-01-01

    Adaptive optics, when integrated into retinal imaging systems, compensates for rapidly changing ocular aberrations in real time and results in improved high resolution images that reveal the photoreceptor mosaic. Imaging the retina at high resolution has numerous potential medical applications, and yet for the development of commercial products that can be used in the clinic, the complexity and high cost of the present research systems have to be addressed. We present a new method to control the deformable mirror in real time based on pupil tracking measurements which uses the default camera for the alignment of the eye in the retinal imaging system and requires no extra cost or hardware. We also present the first experiments done with a compact adaptive optics flood illumination fundus camera where it was possible to compensate for the higher order aberrations of a moving model eye and in vivo in real time based on pupil tracking measurements, without the real time contribution of a wavefront sensor. As an outcome of this research, we showed that pupil tracking can be effectively used as a low cost and practical adaptive optics tool for high resolution retinal imaging because eye movements constitute an important part of the ocular wavefront dynamics. PMID:22312577

  7. Dual-thread parallel control strategy for ophthalmic adaptive optics.

    PubMed

    Yu, Yongxin; Zhang, Yuhua

    To improve ophthalmic adaptive optics speed and compensate for ocular wavefront aberration of high temporal frequency, the adaptive optics wavefront correction has been implemented with a control scheme including 2 parallel threads; one is dedicated to wavefront detection and the other conducts wavefront reconstruction and compensation. With a custom Shack-Hartmann wavefront sensor that measures the ocular wave aberration with 193 subapertures across the pupil, adaptive optics has achieved a closed loop updating frequency up to 110 Hz, and demonstrated robust compensation for ocular wave aberration up to 50 Hz in an adaptive optics scanning laser ophthalmoscope.

  8. Thermally tuneable optical modulator adapted for differential signaling

    DOEpatents

    Zortman, William A.

    2016-01-12

    An apparatus for optical modulation is provided. The apparatus includes a modulator structure and a heater structure. The modulator structure comprises a ring or disk optical resonator having a closed curvilinear periphery and a pair of oppositely doped semiconductor regions within and/or adjacent to the optical resonator and conformed to modify the optical length of the optical resonator upon application of a bias voltage. The heater structure comprises a relatively resistive annulus of semiconductor material enclosed between an inner disk and an outer annulus of relatively conductive semiconductor material. The inner disk and the outer annulus are adapted as contact regions for a heater activation current. The heater structure is situated within the periphery of the optical resonator such that in operation, at least a portion of the resonator is heated by radial conductive heat flow from the heater structure. The apparatus further includes a substantially annular isolation region of dielectric or relatively resistive semiconductor material interposed between the heater structure and the modulator structure. The isolation region is effective to electrically isolate the bias voltage from the heater activation current.

  9. Adaptive Optics at the World's Biggest Optical Telescope

    NASA Astrophysics Data System (ADS)

    Hart, M.; Esposito, S.; Rabien, S.

    2010-09-01

    The Large Binocular Telescope (LBT) on Mt. Graham, Arizona, comprises two 8.4 m primary mirrors on a common mount. The two apertures will be co-phased to create a single telescope with 110 m2 of collecting area and 22.7 m baseline. From the outset, adaptive optics (AO) was incorporated into the design through two adaptive secondary mirrors (ASM), each 91 cm in diameter with 672 actuators, which feed all of the instruments mounted at the telescope's four pairs of Gregorian foci. The first ASM has now seen first light on sky with natural guide stars. Strehl ratios at 1.6 μm under average seeing are estimated to be ~80%, and diffraction-limited performance is maintained for stars down to magnitude 15. At the same time, pioneering work at the 6.5 m MMT telescope has for the first time shown the compelling benefits of ground-layer AO compensation. This technique relies on the signals from multiple laser beacons to sense and correct aberration arising close to the telescope with the result that near IR seeing is reduced by a factor of 2-3 over a field of many arc minutes. Building on these efforts at both telescopes, a project is underway to enhance the LBT's AO capability by the addition of wavefront sensing with multiple laser guide stars. The Advanced Rayleigh Ground-layer adaptive Optics System (ARGOS) is now in the construction phase. We provide an overview of ARGOS and how it foreshadows AO systems destined for the 30 m class telescopes of tomorrow.

  10. Adaptive interferometric null testing for unknown freeform optics metrology.

    PubMed

    Huang, Lei; Choi, Heejoo; Zhao, Wenchuan; Graves, Logan R; Kim, Dae Wook

    2016-12-01

    We report an adaptive interferometric null testing method for overcoming the dynamic range limitations of conventional null testing approaches during unknown freeform optics metrology or optics manufacturing processes that require not-yet-completed surface measurements to guide the next fabrication process. In the presented adaptive method, a deformable mirror functions as an adaptable null component for an unknown optical surface. The optimal deformable mirror's shape is determined by the stochastic parallel gradient descent algorithm and controlled by a deflectometry system. An adaptive interferometric null testing setup was constructed, and its metrology data successfully demonstrated superb adaptive capability in measuring an unknown surface.

  11. Local, hierarchic, and iterative reconstructors for adaptive optics

    NASA Astrophysics Data System (ADS)

    MacMartin, Douglas G.

    2003-06-01

    Adaptive optics systems for future large optical telescopes may require thousands of sensors and actuators. Optimal reconstruction of phase errors using relative measurements requires feedback from every sensor to each actuator, resulting in computational scaling for n actuators of n2. The optimum local reconstructor is investigated, wherein each actuator command depends only on sensor information in a neighboring region. The resulting performance degradation on ``global'' modes is quantified analytically, and two approaches are considered for recovering global performance. Combining local and global estimators in a two-layer hierarchic architecture yields computations scaling with n4/3; extending this approach to multiple layers yields linear scaling. An alternative approach that maintains a local structure is to allow actuator commands to depend on both local sensors and prior local estimates. This iterative approach is equivalent to a temporal low-pass filter on global information and gives a scaling of n3/2. The algorithms are simulated by using data from the Palomar Observatory adaptive optics system. The analysis is general enough to also be applicable to active optics or other systems with many sensors and actuators.

  12. Holographic Adaptive Laser Optics System (HALOS): Fast, Autonomous Aberration Correction

    NASA Astrophysics Data System (ADS)

    Andersen, G.; MacDonald, K.; Gelsinger-Austin, P.

    2013-09-01

    We present an adaptive optics system which uses a multiplexed hologram to deconvolve the phase aberrations in an input beam. This wavefront characterization is extremely fast as it is based on simple measurements of the intensity of focal spots and does not require any computations. Furthermore, the system does not require a computer in the loop and is thus much cheaper, less complex and more robust as well. A fully functional, closed-loop prototype incorporating a 32-element MEMS mirror has been constructed. The unit has a footprint no larger than a laptop but runs at a bandwidth of 100kHz over an order of magnitude faster than comparable, conventional systems occupying a significantly larger volume. Additionally, since the sensing is based on parallel, all-optical processing, the speed is independent of actuator number running at the same bandwidth for one actuator as for a million. We are developing the HALOS technology with a view towards next-generation surveillance systems for extreme adaptive optics applications. These include imaging, lidar and free-space optical communications for unmanned aerial vehicles and SSA. The small volume is ideal for UAVs, while the high speed and high resolution will be of great benefit to the ground-based observation of space-based objects.

  13. Adaptive optics optical coherence tomography at 1 MHz

    PubMed Central

    Kocaoglu, Omer P.; Turner, Timothy L.; Liu, Zhuolin; Miller, Donald T.

    2014-01-01

    Image acquisition speed of optical coherence tomography (OCT) remains a fundamental barrier that limits its scientific and clinical utility. Here we demonstrate a novel multi-camera adaptive optics (AO-)OCT system for ophthalmologic use that operates at 1 million A-lines/s at a wavelength of 790 nm with 5.3 μm axial resolution in retinal tissue. Central to the spectral-domain design is a novel detection channel based on four high-speed spectrometers that receive light sequentially from a 1 × 4 optical switch assembly. Absence of moving parts enables ultra-fast (50ns) and precise switching with low insertion loss (−0.18 dB per channel). This manner of control makes use of all available light in the detection channel and avoids camera dead-time, both critical for imaging at high speeds. Additional benefit in signal-to-noise accrues from the larger numerical aperture afforded by the use of AO and yields retinal images of comparable dynamic range to that of clinical OCT. We validated system performance by a series of experiments that included imaging in both model and human eyes. We demonstrated the performance of our MHz AO-OCT system to capture detailed images of individual retinal nerve fiber bundles and cone photoreceptors. This is the fastest ophthalmic OCT system we know of in the 700 to 915 nm spectral band. PMID:25574431

  14. Adaptive optics optical coherence tomography at 1 MHz.

    PubMed

    Kocaoglu, Omer P; Turner, Timothy L; Liu, Zhuolin; Miller, Donald T

    2014-12-01

    Image acquisition speed of optical coherence tomography (OCT) remains a fundamental barrier that limits its scientific and clinical utility. Here we demonstrate a novel multi-camera adaptive optics (AO-)OCT system for ophthalmologic use that operates at 1 million A-lines/s at a wavelength of 790 nm with 5.3 μm axial resolution in retinal tissue. Central to the spectral-domain design is a novel detection channel based on four high-speed spectrometers that receive light sequentially from a 1 × 4 optical switch assembly. Absence of moving parts enables ultra-fast (50ns) and precise switching with low insertion loss (-0.18 dB per channel). This manner of control makes use of all available light in the detection channel and avoids camera dead-time, both critical for imaging at high speeds. Additional benefit in signal-to-noise accrues from the larger numerical aperture afforded by the use of AO and yields retinal images of comparable dynamic range to that of clinical OCT. We validated system performance by a series of experiments that included imaging in both model and human eyes. We demonstrated the performance of our MHz AO-OCT system to capture detailed images of individual retinal nerve fiber bundles and cone photoreceptors. This is the fastest ophthalmic OCT system we know of in the 700 to 915 nm spectral band.

  15. Applications of lobster eye optics

    NASA Astrophysics Data System (ADS)

    Hudec, R.; Pina, L.; Inneman, A.; Tichy, V.

    2015-05-01

    Applications of wide field Lobster Eye X ray telescopes are presented and discussed. The wide field X ray optics was originally proposed for use in X-ray astronomy, but there are numerous other application areas as well.

  16. Adaptive Optics Imaging and Spectroscopy of Neptune

    NASA Technical Reports Server (NTRS)

    Johnson, Lindley (Technical Monitor); Sromovsky, Lawrence A.

    2005-01-01

    OBJECTIVES: We proposed to use high spectral resolution imaging and spectroscopy of Neptune in visible and near-IR spectral ranges to advance our understanding of Neptune s cloud structure. We intended to use the adaptive optics (AO) system at Mt. Wilson at visible wavelengths to try to obtain the first groundbased observations of dark spots on Neptune; we intended to use A 0 observations at the IRTF to obtain near-IR R=2000 spatially resolved spectra and near-IR A0 observations at the Keck observatory to obtain the highest spatial resolution studies of cloud feature dynamics and atmospheric motions. Vertical structure of cloud features was to be inferred from the wavelength dependent absorption of methane and hydrogen,

  17. Wavefront Control for Extreme Adaptive Optics

    SciTech Connect

    Poyneer, L A

    2003-07-16

    Current plans for Extreme Adaptive Optics systems place challenging requirements on wave-front control. This paper focuses on control system dynamics, wave-front sensing and wave-front correction device characteristics. It may be necessary to run an ExAO system after a slower, low-order AO system. Running two independent systems can result in very good temporal performance, provided specific design constraints are followed. The spatially-filtered wave-front sensor, which prevents aliasing and improves PSF sensitivity, is summarized. Different models of continuous and segmented deformable mirrors are studied. In a noise-free case, a piston-tip-tilt segmented MEMS device can achieve nearly equivalent performance to a continuous-sheet DM in compensating for a static phase aberration with use of spatial filtering.

  18. Wavefront control for extreme adaptive optics

    NASA Astrophysics Data System (ADS)

    Poyneer, Lisa A.; Macintosh, Bruce A.

    2003-12-01

    Current plans for Extreme Adaptive Optics systems place challenging requirements on wave-front control. This paper focuses on control system dynamics, wave-front sensing and wave-front correction device characteristics. It may be necessary to run an ExAO system after a slower, low-order AO system. Running two independent systems can result in very good temporal performance, provided specific design constraints are followed. The spatially-filtered wave-front sensor, which prevents aliasing and improves PSF sensitivity, is summarized. Different models of continuous and segmented deformable mirrors are studied. In a noise-free case, a piston-tip-tilt segmented MEMS device can achieve nearly equivalent performance to a continuous-sheet DM in compensating for a static phase aberration with use of spatial filtering.

  19. Fast, compact, autonomous holographic adaptive optics.

    PubMed

    Andersen, Geoff; Gelsinger-Austin, Paul; Gaddipati, Ravi; Gaddipati, Phani; Ghebremichael, Fassil

    2014-04-21

    We present a closed-loop adaptive optics system based on a holographic sensing method. The system uses a multiplexed holographic recording of the response functions of each actuator in a deformable mirror. By comparing the output intensity measured in a pair of photodiodes, the absolute phase can be measured over each actuator location. From this a feedback correction signal is applied to the input beam without need for a computer. The sensing and correction is applied to each actuator in parallel, so the bandwidth is independent of the number of actuator. We demonstrate a breadboard system using a 32-actuator MEMS deformable mirror capable of operating at over 10 kHz without a computer in the loop.

  20. Field-Sensitive Materials for Optical Applications

    NASA Technical Reports Server (NTRS)

    Choi, Sang H.; Little, Mark

    2002-01-01

    The purpose of investigation is to develop the fundamental materials and fabrication technology for field-controlled spectrally active optics that are essential for industry, NASA, and DOD (Department of Defense) applications such as: membrane optics, filters for LIDARs (Light Detection and Ranging), windows for sensors and probes, telescopes, spectroscopes, cameras, light valves, light switches, flat-panel displays, etc. The proposed idea is based on the quantum-dots (QD) array or thin-film of field-sensitive Stark and Zeeman materials and the bound excitonic state of organic crystals that will offer optical adaptability and reconfigurability. Major tasks are the development of concept demonstration article and test data of field-controlled spectrally smart active optics (FCSAO) for optical multi-functional capabilities on a selected spectral range.

  1. ESO adaptive optics facility progress report

    NASA Astrophysics Data System (ADS)

    Arsenault, Robin; Madec, Pierre-Yves; Paufique, Jerome; La Penna, Paolo; Stroebele, Stefan; Vernet, Elise; Pirard, Jean-Francois; Hackenberg, Wolfgang; Kuntschner, Harald; Jochum, Lieselotte; Kolb, Johann; Muller, Nicolas; Le Louarn, Miska; Amico, Paola; Hubin, Norbert; Lizon, Jean-Louis; Ridings, Rob; Abad, Jose A.; Fischer, Gert; Heinz, Volker; Kiekebusch, Mario; Argomedo, Javier; Conzelmann, Ralf; Tordo, Sebastien; Donaldson, Robert; Soenke, Christian; Duhoux, Philippe; Fedrigo, Enrico; Delabre, Bernard; Jost, Andreas; Duchateau, Michel; Downing, Mark; Moreno, Javier R.; Dorn, Reinhold; Manescau, Antonio; Bonaccini Calia, Domenico; Quattri, Marco; Dupuy, Christophe; Guidolin, Ivan M.; Comin, Mauro; Guzman, Ronald; Buzzoni, Bernard; Quentin, Jutta; Lewis, Steffan; Jolley, Paul; Kraus, Maximilian; Pfrommer, Thomas; Biasi, Roberto; Gallieni, Daniele; Bechet, Clementine; Stuik, Remko

    2012-07-01

    The ESO Adaptive Optics Facility (AOF) consists in an evolution of one of the ESO VLT unit telescopes to a laser driven adaptive telescope with a deformable mirror in its optical train. The project has completed the procurement phase and several large structures have been delivered to Garching (Germany) and are being integrated (the AO modules GRAAL and GALACSI and the ASSIST test bench). The 4LGSF Laser (TOPTICA) has undergone final design review and a pre-production unit has been built and successfully tested. The Deformable Secondary Mirror is fully integrated and system tests have started with the first science grade thin shell mirror delivered by SAGEM. The integrated modules will be tested in stand-alone mode in 2012 and upon delivery of the DSM in late 2012, the system test phase will start. A commissioning strategy has been developed and will be updated before delivery to Paranal. A substantial effort has been spent in 2011-2012 to prepare the unit telescope to receive the AOF by preparing the mechanical interfaces and upgrading the cooling and electrical network. This preparation will also simplify the final installation of the facility on the telescope. A lot of attention is given to the system calibration, how to record and correct any misalignment and control the whole facility. A plan is being developed to efficiently operate the AOF after commissioning. This includes monitoring a relevant set of atmospheric parameters for scheduling and a Laser Traffic control system to assist the operator during the night and help/support the observing block preparation.

  2. Adaptive optics without altering visual perception.

    PubMed

    Koenig, D E; Hart, N W; Hofer, H J

    2014-04-01

    Adaptive optics combined with visual psychophysics creates the potential to study the relationship between visual function and the retina at the cellular scale. This potential is hampered, however, by visual interference from the wavefront-sensing beacon used during correction. For example, we have previously shown that even a dim, visible beacon can alter stimulus perception (Hofer et al., 2012). Here we describe a simple strategy employing a longer wavelength (980nm) beacon that, in conjunction with appropriate restriction on timing and placement, allowed us to perform psychophysics when dark adapted without altering visual perception. The method was verified by comparing detection and color appearance of foveally presented small spot stimuli with and without the wavefront beacon present in 5 subjects. As an important caution, we found that significant perceptual interference can occur even with a subliminal beacon when additional measures are not taken to limit exposure. Consequently, the lack of perceptual interference should be verified for a given system, and not assumed based on invisibility of the beacon. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Adaptive optics for the CHARA array

    NASA Astrophysics Data System (ADS)

    ten Brummelaar, Theo A.; Sturmann, Laszlo; Sturmann, Judit; Ridgway, Stephen T.; Monnier, John D.; Ireland, Michael J.; Che, Xiao; McAlister, Harold A.; Turner, Nils H.; Tuthill, P. G.

    2012-07-01

    The CHARA Array is a six telescope optical/IR interferometer run by the Center for High Angular Resolution Astronomy of Georgia State University and is located at Mount Wilson Observatory just to the north of Los Angeles California. The CHARA Array has the largest operational baselines in the world and has been in regular use for scientific observations since 2004. In 2011 we received funding from the NSF to begin work on Adaptive Optics for our six telescopes. Phase I of this project, fully funded by the NSF grant, consists of designing and building wavefront sensors for each telescope that will also serve as tip/tilt detectors. Having tip/tilt at the telescopes, instead of in the laboratory, will add several magnitudes of sensitivity to this system. Phase I also includes a slow wavefront sensor in the laboratory to measure non-common path errors and small deformable mirrors in the laboratory to remove static and slowly changing aberrations. Phase II of the project will allow us to place high-speed deformable mirrors at the telescopes thereby enabling full closed loop operation. We are currently seeking funding for Phase II. This paper will describe the scientific rational and design of the system and give the current status of the project.

  4. Adaptive Detector Arrays for Optical Communications Receivers

    NASA Technical Reports Server (NTRS)

    Vilnrotter, V.; Srinivasan, M.

    2000-01-01

    The structure of an optimal adaptive array receiver for ground-based optical communications is described and its performance investigated. Kolmogorov phase screen simulations are used to model the sample functions of the focal-plane signal distribution due to turbulence and to generate realistic spatial distributions of the received optical field. This novel array detector concept reduces interference from background radiation by effectively assigning higher confidence levels at each instant of time to those detector elements that contain significant signal energy and suppressing those that do not. A simpler suboptimum structure that replaces the continuous weighting function of the optimal receiver by a hard decision on the selection of the signal detector elements also is described and evaluated. Approximations and bounds to the error probability are derived and compared with the exact calculations and receiver simulation results. It is shown that, for photon-counting receivers observing Poisson-distributed signals, performance improvements of approximately 5 dB can be obtained over conventional single-detector photon-counting receivers, when operating in high background environments.

  5. Low-cost adaptive directly modulated optical OFDM based on semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Kashany-Mizrahi, Inbal; Sadot, Dan

    2013-10-01

    Low cost optical OFDM has great potential for next generation optical access networks and PONs, due to its high flexibility in bandwidth manipulation, and high spectral efficiency. Here, a low cost optical OFDM is proposed, based on adaptive direct modulation semiconductor optical amplifier. Adaptive current loading techniques for PAPR (peak to average power ratio) reduction are proposed and analyzed. Simulations show that the proposed adaptive techniques enable significant BER improvement.

  6. Proposed multiconjugate adaptive optics experiment at Lick Observatory

    NASA Astrophysics Data System (ADS)

    Bauman, Brian J.; Gavel, Donald T.; Flath, Laurence M.; Hurd, Randall L.; Max, Claire E.; Olivier, Scot S.

    2002-02-01

    While the theory behind design of multiconjugate adaptive optics (MCAO) systems is growing, there is still a paucity of experience building and testing such instruments. We propose using the Lick adaptive optics (AO) system as a basis for demonstrating the feasibility/workability of MCAO systems, testing underlying assumptions, and experimenting with different approaches to solving MCAO system issues.

  7. Proposed Multiconjugate Adaptive Optics Experiment at Lick Observatory

    SciTech Connect

    Bauman, B J; Gavel, D T; Flath, L M; Hurd, R L; Max, C E; Olivier, S S

    2001-08-15

    While the theory behind design of multiconjugate adaptive optics (MCAO) systems is growing, there is still a paucity of experience building and testing such instruments. We propose using the Lick adaptive optics (AO) system as a basis for demonstrating the feasibility/workability of MCAO systems, testing underlying assumptions, and experimenting with different approaches to solving MCAO system issues.

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

    NASA Astrophysics Data System (ADS)

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

    2003-02-01

    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 removed by corrective optics. For economic reasons, these remote sensing systems must have a large field-of-view (a few degrees). Unlike ground-based adaptive optical systems, which have a negligible field-of-view, the adaptive optics on these space-based remote sensing systems will be required to correct for the deformations in the primary mirror over the entire field-of-view. A new error function, which is an enhancement to conventional adaptive optics, for wide field-of-view optical systems will be introduced. This paper will present the goals of the NASA research project and its progress. The initial phase of this research project is a demonstration of the wide field-of-view adaptive optics theory. A breadboard has been designed and built for this purpose. The design and assembly of the breadboard will be presented, along with the final results for this phase of the research project. Finally, this paper will show the applicability of wide field-of-view adaptive optics to space-based astronomical systems.

  9. Adaptive optics optical coherence tomography with dynamic retinal tracking

    PubMed Central

    Kocaoglu, Omer P.; Ferguson, R. Daniel; Jonnal, Ravi S.; Liu, Zhuolin; Wang, Qiang; Hammer, Daniel X.; Miller, Donald T.

    2014-01-01

    Adaptive optics optical coherence tomography (AO-OCT) is a highly sensitive and noninvasive method for three dimensional imaging of the microscopic retina. Like all in vivo retinal imaging techniques, however, it suffers the effects of involuntary eye movements that occur even under normal fixation. In this study we investigated dynamic retinal tracking to measure and correct eye motion at KHz rates for AO-OCT imaging. A customized retina tracking module was integrated into the sample arm of the 2nd-generation Indiana AO-OCT system and images were acquired on three subjects. Analyses were developed based on temporal amplitude and spatial power spectra in conjunction with strip-wise registration to independently measure AO-OCT tracking performance. After optimization of the tracker parameters, the system was found to correct eye movements up to 100 Hz and reduce residual motion to 10 µm root mean square. Between session precision was 33 µm. Performance was limited by tracker-generated noise at high temporal frequencies. PMID:25071963

  10. Adaptive optics optical coherence tomography with dynamic retinal tracking.

    PubMed

    Kocaoglu, Omer P; Ferguson, R Daniel; Jonnal, Ravi S; Liu, Zhuolin; Wang, Qiang; Hammer, Daniel X; Miller, Donald T

    2014-07-01

    Adaptive optics optical coherence tomography (AO-OCT) is a highly sensitive and noninvasive method for three dimensional imaging of the microscopic retina. Like all in vivo retinal imaging techniques, however, it suffers the effects of involuntary eye movements that occur even under normal fixation. In this study we investigated dynamic retinal tracking to measure and correct eye motion at KHz rates for AO-OCT imaging. A customized retina tracking module was integrated into the sample arm of the 2nd-generation Indiana AO-OCT system and images were acquired on three subjects. Analyses were developed based on temporal amplitude and spatial power spectra in conjunction with strip-wise registration to independently measure AO-OCT tracking performance. After optimization of the tracker parameters, the system was found to correct eye movements up to 100 Hz and reduce residual motion to 10 µm root mean square. Between session precision was 33 µm. Performance was limited by tracker-generated noise at high temporal frequencies.

  11. Speckle statistics in adaptive optics images at visible wavelengths

    NASA Astrophysics Data System (ADS)

    Stangalini, Marco; Pedichini, Fernando; Ambrosino, Filippo; Centrone, Mauro; Del Moro, Dario

    2016-07-01

    Residual speckles in adaptive optics (AO) images represent a well known limitation to the achievement of the contrast needed for faint stellar companions detection. Speckles in AO imagery can be the result of either residual atmospheric aberrations, not corrected by the AO, or slowly evolving aberrations induced by the optical system. In this work we take advantage of new high temporal cadence (1 ms) data acquired by the SHARK forerunner experiment at the Large Binocular Telescope (LBT), to characterize the AO residual speckles at visible waveleghts. By means of an automatic identification of speckles, we study the main statistical properties of AO residuals. In addition, we also study the memory of the process, and thus the clearance time of the atmospheric aberrations, by using information Theory. These information are useful for increasing the realism of numerical simulations aimed at assessing the instrumental performances, and for the application of post-processing techniques on AO imagery.

  12. Fourier transform digital holographic adaptive optics imaging system

    PubMed Central

    Liu, Changgeng; Yu, Xiao; Kim, Myung K.

    2013-01-01

    A Fourier transform digital holographic adaptive optics imaging system and its basic principles are proposed. The CCD is put at the exact Fourier transform plane of the pupil of the eye lens. The spherical curvature introduced by the optics except the eye lens itself is eliminated. The CCD is also at image plane of the target. The point-spread function of the system is directly recorded, making it easier to determine the correct guide-star hologram. Also, the light signal will be stronger at the CCD, especially for phase-aberration sensing. Numerical propagation is avoided. The sensor aperture has nothing to do with the resolution and the possibility of using low coherence or incoherent illumination is opened. The system becomes more efficient and flexible. Although it is intended for ophthalmic use, it also shows potential application in microscopy. The robustness and feasibility of this compact system are demonstrated by simulations and experiments using scattering objects. PMID:23262541

  13. Multiwavelength adaptive optical fundus camera and continuous retinal imaging

    NASA Astrophysics Data System (ADS)

    Yang, Han-sheng; Li, Min; Dai, Yun; Zhang, Yu-dong

    2009-08-01

    We have constructed a new version of retinal imaging system with chromatic aberration concerned and the correlated optical design presented in this article is based on the adaptive optics fundus camera modality. In our system, three typical wavelengths of 550nm, 650nm and 480nm were selected. Longitude chromatic aberration (LCA) was traded off to a minimum using ZEMAX program. The whole setup was actually evaluated on human subjects and retinal imaging was performed at continuous frame rates up to 20 Hz. Raw videos at parafovea locations were collected, and cone mosaics as well as retinal vasculature were clearly observed in one single clip. In addition, comparisons under different illumination conditions were also made to confirm our design. Image contrast and the Strehl ratio were effectively increased after dynamic correction of high order aberrations. This system is expected to bring new applications in functional imaging of human retina.

  14. Fourier transform digital holographic adaptive optics imaging system.

    PubMed

    Liu, Changgeng; Yu, Xiao; Kim, Myung K

    2012-12-10

    A Fourier transform digital holographic adaptive optics imaging system and its basic principles are proposed. The CCD is put at the exact Fourier transform plane of the pupil of the eye lens. The spherical curvature introduced by the optics except the eye lens itself is eliminated. The CCD is also at image plane of the target. The point-spread function of the system is directly recorded, making it easier to determine the correct guide-star hologram. Also, the light signal will be stronger at the CCD, especially for phase-aberration sensing. Numerical propagation is avoided. The sensor aperture has nothing to do with the resolution and the possibility of using low coherence or incoherent illumination is opened. The system becomes more efficient and flexible. Although it is intended for ophthalmic use, it also shows potential application in microscopy. The robustness and feasibility of this compact system are demonstrated by simulations and experiments using scattering objects.

  15. Adapting smartphones for low-cost optical medical imaging

    NASA Astrophysics Data System (ADS)

    Pratavieira, Sebastião.; Vollet-Filho, José D.; Carbinatto, Fernanda M.; Blanco, Kate; Inada, Natalia M.; Bagnato, Vanderlei S.; Kurachi, Cristina

    2015-06-01

    Optical images have been used in several medical situations to improve diagnosis of lesions or to monitor treatments. However, most systems employ expensive scientific (CCD or CMOS) cameras and need computers to display and save the images, usually resulting in a high final cost for the system. Additionally, this sort of apparatus operation usually becomes more complex, requiring more and more specialized technical knowledge from the operator. Currently, the number of people using smartphone-like devices with built-in high quality cameras is increasing, which might allow using such devices as an efficient, lower cost, portable imaging system for medical applications. Thus, we aim to develop methods of adaptation of those devices to optical medical imaging techniques, such as fluorescence. Particularly, smartphones covers were adapted to connect a smartphone-like device to widefield fluorescence imaging systems. These systems were used to detect lesions in different tissues, such as cervix and mouth/throat mucosa, and to monitor ALA-induced protoporphyrin-IX formation for photodynamic treatment of Cervical Intraepithelial Neoplasia. This approach may contribute significantly to low-cost, portable and simple clinical optical imaging collection.

  16. Design and progress toward a multi-conjugate adaptive optics system for distributed aberration correction

    SciTech Connect

    Baker, K; Olivier, S; Tucker, J; Silva, D; Gavel, D; Lim, R; Gratrix, E

    2004-08-17

    This article investigates the use of a multi-conjugate adaptive optics system to improve the field-of-view for the system. The emphasis of this research is to develop techniques to improve the performance of optical systems with applications to horizontal imaging. The design and wave optics simulations of the proposed system are given. Preliminary results from the multi-conjugate adaptive optics system are also presented. The experimental system utilizes a liquid-crystal spatial light modulator and an interferometric wave-front sensor for correction and sensing of the phase aberrations, respectively.

  17. The research and development of the adaptive optics in ophthalmology

    NASA Astrophysics Data System (ADS)

    Wu, Chuhan; Zhang, Xiaofang; Chen, Weilin

    2015-08-01

    Recently the combination of adaptive optics and ophthalmology has made great progress and become highly effective. The retina disease is diagnosed by retina imaging technique based on scanning optical system, so the scanning of eye requires optical system characterized by great ability of anti-moving and optical aberration correction. The adaptive optics possesses high level of adaptability and is available for real time imaging, which meets the requirement of medical retina detection with accurate images. Now the Scanning Laser Ophthalmoscope and the Optical Coherence Tomography are widely used, which are the core techniques in the area of medical retina detection. Based on the above techniques, in China, a few adaptive optics systems used for eye medical scanning have been designed by some researchers from The Institute of Optics And Electronics of CAS(The Chinese Academy of Sciences); some foreign research institutions have adopted other methods to eliminate the interference of eye moving and optical aberration; there are many relevant patents at home and abroad. In this paper, the principles and relevant technique details of the Scanning Laser Ophthalmoscope and the Optical Coherence Tomography are described. And the recent development and progress of adaptive optics in the field of eye retina imaging are analyzed and summarized.

  18. Configurable adaptive optical system for imaging of ground-based targets from space

    NASA Astrophysics Data System (ADS)

    McComas, Brian K.; Friedman, Edward J.; Hooker, R. Brian; Cermak, Michael A.

    2003-03-01

    Space-based, high resolution, Earth remote sensing systems, that employ large, flexible, lightweight primary mirrors, will require active wavefront correction, in the form of active and adaptive optics, to correct for thermally and vibrationally induced deformations in the optics. These remote sensing systems typically have a large field-of-view. Unlike the adaptive optics on ground-based astronomical telescopes, which have a negligible field-of-view, the adaptive optics on these space-based remote sensing systems will be required to correct the wavefront over the entire field-of-view, which can be several degrees. The error functions for astronomical adaptive optics have been developed for the narrow field-of-view correction of atmospheric turbulence and do not address the needs of wide field space-based systems. To address these needs, a new wide field adaptive optics theory and a new error function are developed. Modeling and experimental results demonstrate the validity of the wide field adaptive optics theory and new error function. This new error function, which is a new extension of conventional adaptive optics, lead to the development of three new types of imaging systems: wide field-of-view, selectable field-of-view, and steerable field-of-view. These new systems can have nearly diffraction-limited performance across the entire field-of-view or a narrow movable region of high-resolution imaging. The factors limiting system performance will be shown. The range of applicability of the wide field adaptive optics theory is shown. The range of applicability is used to avoid limitations in system performance and to estimate the optical systems parameters, which will meet the system"s performance requirements.

  19. Optimized micromirror arrays for adaptive optics

    NASA Astrophysics Data System (ADS)

    Michalicek, M. Adrian; Comtois, John H.; Hetherington, Dale L.

    1999-01-01

    This paper describes the design, layout, fabrication, and surface characterization of highly optimized surface micromachined micromirror devices. Design considerations and fabrication capabilities are presented. These devices are fabricated in the state-of-the-art, four-level, planarized, ultra-low-stress polysilicon process available at Sandia National Laboratories known as the Sandia Ultra-planar Multi-level MEMS Technology (SUMMiT). This enabling process permits the development of micromirror devices with near-ideal characteristics that have previously been unrealizable in standard three-layer polysilicon processes. The reduced 1 μm minimum feature sizes and 0.1 μm mask resolution make it possible to produce dense wiring patterns and irregularly shaped flexures. Likewise, mirror surfaces can be uniquely distributed and segmented in advanced patterns and often irregular shapes in order to minimize wavefront error across the pupil. The ultra-low-stress polysilicon and planarized upper layer allow designers to make larger and more complex micromirrors of varying shape and surface area within an array while maintaining uniform performance of optical surfaces. Powerful layout functions of the AutoCAD editor simplify the design of advanced micromirror arrays and make it possible to optimize devices according to the capabilities of the fabrication process. Micromirrors fabricated in this process have demonstrated a surface variance across the array from only 2-3 nm to a worst case of roughly 25 nm while boasting active surface areas of 98% or better. Combining the process planarization with a ``planarized-by-design'' approach will produce micromirror array surfaces that are limited in flatness only by the surface deposition roughness of the structural material. Ultimately, the combination of advanced process and layout capabilities have permitted the fabrication of highly optimized micromirror arrays for adaptive optics.

  20. Optimized micromirror arrays for adaptive optics

    SciTech Connect

    Michalicek, M. Adrian Comtois, John H. Hetherington, Dale L.

    1999-01-01

    This paper describes the design, layout, fabrication, and surface characterization of highly optimized surface micromachined micromirror devices. Design considerations and fabrication capabilities are presented. These devices are fabricated in the state-of-the-art, four-level, planarized, ultra-low-stress polysilicon process available at Sandia National Laboratories known as the Sandia Ultra-planar Multi-level MEMS Technology (SUMMiT). This enabling process permits the development of micromirror devices with near-ideal characteristics that have previously been unrealizable in standard three-layer polysilicon processes. The reduced 1 {mu}m minimum feature sizes and 0.1 {mu}m mask resolution make it possible to produce dense wiring patterns and irregularly shaped flexures. Likewise, mirror surfaces can be uniquely distributed and segmented in advanced patterns and often irregular shapes in order to minimize wavefront error across the pupil. The ultra-low-stress polysilicon and planarized upper layer allow designers to make larger and more complex micromirrors of varying shape and surface area within an array while maintaining uniform performance of optical surfaces. Powerful layout functions of the AutoCAD editor simplify the design of advanced micromirror arrays and make it possible to optimize devices according to the capabilities of the fabrication process. Micromirrors fabricated in this process have demonstrated a surface variance across the array from only 2{endash}3 nm to a worst case of roughly 25 nm while boasting active surface areas of 98{percent} or better. Combining the process planarization with a {open_quotes}planarized-by-design{close_quotes} approach will produce micromirror array surfaces that are limited in flatness only by the surface deposition roughness of the structural material. Ultimately, the combination of advanced process and layout capabilities have permitted the fabrication of highly optimized micromirror arrays for adaptive optics

  1. Design optimization of system level adaptive optical performance

    NASA Astrophysics Data System (ADS)

    Michels, Gregory J.; Genberg, Victor L.; Doyle, Keith B.; Bisson, Gary R.

    2005-09-01

    By linking predictive methods from multiple engineering disciplines, engineers are able to compute more meaningful predictions of a product's performance. By coupling mechanical and optical predictive techniques mechanical design can be performed to optimize optical performance. This paper demonstrates how mechanical design optimization using system level optical performance can be used in the development of the design of a high precision adaptive optical telescope. While mechanical design parameters are treated as the design variables, the objective function is taken to be the adaptively corrected optical imaging performance of an orbiting two-mirror telescope.

  2. The study on cloud masking of GOCI optical images by using adaptive threshold and BRDF-based NDVI profiles for the land application

    NASA Astrophysics Data System (ADS)

    Kim, H. W.; Yeom, J. M.; Woo, S. H.; Kim, Y. S.; Chae, T. B.

    2015-12-01

    Geostationary Ocean Color Imager (GOCI) which was launched on 27 June 2010, developed to detect, monitor, and predict the ocean phenomena around Korea. Although GOCI was developed to observe the ocean environment, GOCI has also enormous scientific data for land surface. However, it is extremely important to extract the cloud pixels over the land surface to utilize its data for the land application. Over the land surface, the reflectance variation is higher and the characteristic of surface is more various than those over the ocean. Furthermore, the infra-red (IR) channel is not included in 8 GOCI bands, which is useful to detect the thin cloud and the water vapor with cloud top temperature. Nevertheless, GOCI has potential to detect the cloud using the temporal variation due to the characteristics of geostationary satellite observation. The purpose of this study is to estimate the cloud masking maps over the Korean Peninsula. For cloud masking with GOCI, following methods are used; simple threshold with reflectance and ratio of bands, adaptive threshold with multi-temporal images, and stable multi-temporal vegetation image. In the case of adaptive threshold, high variable cloudy when comparing with surface reflectance is used by comparing the surface reflectance by temporal based analysis. In this study, the multi-temporal NDVI data processed by the bi-directional reflectance distribution function (BRDF) modeling also used to reflect the relative solar-target-sensor geometry during the daytime. This result will have a substantial role for the land application using GOCI data.

  3. Graphite/Cyanate Ester Face Sheets for Adaptive Optics

    NASA Technical Reports Server (NTRS)

    Bennett, Harold; Shaffer, Joseph; Romeo, Robert

    2008-01-01

    It has been proposed that thin face sheets of wide-aperture deformable mirrors in adaptive-optics systems be made from a composite material consisting of cyanate ester filled with graphite. This composite material appears to offer an attractive alternative to low-thermal-expansion glasses that are used in some conventional optics and have been considered for adaptive-optics face sheets. Adaptive-optics face sheets are required to have maximum linear dimensions of the order of meters or even tens of meters for some astronomical applications. If the face sheets were to be made from low-thermal-expansion glasses, then they would also be required to have thicknesses of the order of a millimeter so as to obtain the optimum compromise between the stiffness needed for support and the flexibility needed to enable deformation to controlled shapes by use of actuators. It is difficult to make large glass sheets having thicknesses less than 3 mm, and 3-mm-thick glass sheets are too stiff to be deformable to the shapes typically required for correction of wavefronts of light that has traversed the terrestrial atmosphere. Moreover, the primary commercially produced candidate low-thermal-expansion glass is easily fractured when in the form of thin face sheets. Graphite-filled cyanate ester has relevant properties similar to those of the low-expansion glasses. These properties include a coefficient of thermal expansion (CTE) of the order of a hundredth of the CTEs of other typical mirror materials. The Young s modulus (which quantifies stiffness in tension and compression) of graphite-filled cyanate ester is also similar to the Young's moduli of low-thermal-expansion glasses. However, the fracture toughness of graphite-filled cyanate ester is much greater than that of the primary candidate low-thermal-expansion glass. Therefore, graphite-filled cyanate ester could be made into nearly unbreakable face sheets, having maximum linear dimensions greater than a meter and thicknesses of

  4. Adaptive Optics Imaging of Exoplanet Host Stars

    NASA Astrophysics Data System (ADS)

    Herman, Miranda; Waaler, Mason; Patience, Jennifer; Ward-Duong, Kimberly; Rajan, Abhijith; McCarthy, Don; Kulesa, Craig; Wilson, Paul A.

    2016-01-01

    With the Arizona Infrared imager and Echelle Spectrograph (ARIES) instrument on the 6.5m MMT telescope, we obtained high angular resolution adaptive optics images of 12 exoplanet host stars. The targets are all systems with exoplanets in extremely close orbits such that the planets transit the host stars and cause regular brightness changes in the stars. The transit depth of the light curve is used to infer the radius and, in combination with radial velocity measurements, the density of the planet, but the results can be biased if the light from the host star is the combined light of a pair of stars in a binary system or a chance alignment of two stars. Given the high frequency of binary star systems and the increasing number of transit exoplanet discoveries from Kepler, K2, and anticipated discoveries with the Transiting Exoplanet Survey Satellite (TESS), this is a crucial point to consider when interpreting exoplanet properties. Companions were identified around five of the twelve targets at separations close enough that the brightness measurements of these host stars are in fact the combined brightness of two stars. Images of the resolved stellar systems and reanalysis of the exoplanet properties accounting for the presence of two stars are presented.

  5. Turbulence profiling for adaptive optics tomographic reconstructors

    NASA Astrophysics Data System (ADS)

    Laidlaw, Douglas J.; Osborn, James; Wilson, Richard W.; Morris, Timothy J.; Butterley, Timothy; Reeves, Andrew P.; Townson, Matthew J.; Gendron, Éric; Vidal, Fabrice; Morel, Carine

    2016-07-01

    To approach optimal performance advanced Adaptive Optics (AO) systems deployed on ground-based telescopes must have accurate knowledge of atmospheric turbulence as a function of altitude. Stereo-SCIDAR is a high-resolution stereoscopic instrument dedicated to this measure. Here, its profiles are directly compared to internal AO telemetry atmospheric profiling techniques for CANARY (Vidal et al. 20141), a Multi-Object AO (MOAO) pathfinder on the William Herschel Telescope (WHT), La Palma. In total twenty datasets are analysed across July and October of 2014. Levenberg-Marquardt fitting algorithms dubbed Direct Fitting and Learn 2 Step (L2S; Martin 20142) are used in the recovery of profile information via covariance matrices - respectively attaining average Pearson product-moment correlation coefficients with stereo-SCIDAR of 0.2 and 0.74. By excluding the measure of covariance between orthogonal Wavefront Sensor (WFS) slopes these results have revised values of 0.65 and 0.2. A data analysis technique that combines L2S and SLODAR is subsequently introduced that achieves a correlation coefficient of 0.76.

  6. KAPAO: A Pomona College Adaptive Optics Instrument

    NASA Astrophysics Data System (ADS)

    Choi, Philip I.; Severson, S. A.; Rudy, A. R.; Gilbreth, B. N.; Contreras, D. S.; McGonigle, L. P.; Chin, R. M.; Horn, B.; Hoidn, O.; Spjut, E.; Baranec, C.; Riddle, R.

    2011-01-01

    We describe our project (KAPAO) to develop and deploy a low-cost, remote-access, natural guide star adaptive optics system for the Pomona College Table Mountain Observatory (TMO) 1-meter telescope. The system will offer simultaneous dual-band, diffraction-limited imaging at visible and near-infrared wavelengths and will deliver an order-of-magnitude improvement in point source sensitivity and angular resolution relative to the current TMO seeing limits. In order to ensure reliability, minimize costs and encourage replication efforts, off-the-shelf components that include a MEMS deformable mirror, a Shack-Hartmann wavefront sensor and a piezo-electric tip-tilt mirror are being adopted for the core hardware elements. We present: the instrument design; performance predictions based on AO simulations; and the current status of the testbed instrument and high-speed control system. Beyond the expanded scientific capabilities enabled by AO-enhanced resolution and sensitivity, the interdisciplinary nature of the instrument development effort provides an exceptional opportunity to train a broad range of undergraduate STEM students in AO technologies and techniques. The breadth of our collaboration, which includes both public (Sonoma State University) and private (Pomona and Harvey Mudd Colleges) undergraduate institutions has enabled us to engage students ranging from physics, astronomy, engineering and computer science in the early stages of this project. This material is based upon work supported by the National Science Foundation under Grant No. 0960343.

  7. Adaptive optics for laser space debris removal

    NASA Astrophysics Data System (ADS)

    Bennet, Francis; Conan, Rodolphe; D'Orgeville, Celine; Dawson, Murray; Paulin, Nicolas; Price, Ian; Rigaut, Francois; Ritchie, Ian; Smith, Craig; Uhlendorf, Kristina

    2012-07-01

    Space debris in low Earth orbit below 1500km is becoming an increasing threat to satellites and spacecrafts. Radar and laser tracking are currently used to monitor the orbits of thousands of space debris and active satellites are able to use this information to manoeuvre out of the way of a predicted collision. However, many satellites are not able to manoeuvre and debris-on debris collisions are becoming a signicant contributor to the growing space debris population. The removal of the space debris from orbit is the preferred and more denitive solution. Space debris removal may be achieved through laser ablation, whereby a high power laser corrected with an adaptive optics system could, in theory, allow ablation of the debris surface and so impart a remote thrust on the targeted object. The goal of this is to avoid collisions between space debris to prevent an exponential increase in the number of space debris objects. We are developing an experiment to demonstrate the feasibility of laser ablation for space debris removal. This laser ablation demonstrator utilises a pulsed sodium laser to probe the atmosphere ahead of the space debris and the sun re ection of the space debris is used to provide atmospheric tip{tilt information. A deformable mirror is then shaped to correct an infrared laser beam on the uplink path to the debris. We present here the design and the expected performance of the system.

  8. Effect of adaptive optical system on the capability of lidar detection in atmosphere

    NASA Astrophysics Data System (ADS)

    Tan, Xue-chun; Wu, Zhi-chao; Liang, Zhu

    2009-05-01

    Since atmosphere turbulence has an effect on laser propagation, it causes wavefront error usually , changes intensity and coherence of laser, disturbs detection of lidar. The adaptive optical system has broad application in the field of laser transmission because it can adjust characters of optical system ,detect and correct the wavefront error at the same time. Adaptive optics technology uses deformable mirrors to perform dynamic phase modulation and endow optical system the ability to decrease the influence of dynamic wavefront errors. In this paper ,a correction method of the micro-miniature adaptive optical system based on Micro Electromechanical System (MEMS) technology is proposed by analyzing the working theory of the adaptive optical system. An experimental system including deformable mirror based on Micro Electromechanical System (MEMS) technology is designed to correct a factitious wavefront error.The influence function and voltage-deflection curve are researched, and the voltage control matrix is educed. By using the voltage control , the static wavefront aberration is corrected. Several important capabilities of deformable mirrors is tested. With the voltage control matrix, the corrected capability of the adaptive optical system is achieved successfully .The experimental results show that the adaptive optical system can preferably correct the wavefront error, that has small volume and steady capability, and greatly improve the capability of lidar detection.

  9. Adaptive x-ray optics development at AOA-Xinetics

    NASA Astrophysics Data System (ADS)

    Lillie, Charles F.; Cavaco, Jeff L.; Brooks, Audrey D.; Ezzo, Kevin; Pearson, David D.; Wellman, John A.

    2013-05-01

    Grazing-incidence optics for X-ray applications require extremely smooth surfaces with precise mirror figures to provide well focused beams and small image spot sizes for astronomical telescopes and laboratory test facilities. The required precision has traditionally been achieved by time-consuming grinding and polishing of thick substrates with frequent pauses for precise metrology to check the mirror figure. More recently, substrates with high quality surface finish and figures have become available at reasonable cost, and techniques have been developed to mechanically adjust the figure of these traditionally polished substrates for ground-based applications. The beam-bending techniques currently in use are mechanically complex, however, with little control over mid-spatial frequency errors. AOA-Xinetics has been developing been developing techniques for shaping grazing incidence optics with surface-normal and surface-parallel electrostrictive Lead magnesium niobate (PMN) actuators bonded to mirror substrates for several years. These actuators are highly reliable; exhibit little to no hysteresis, aging or creep; and can be closely spaced to correct low and mid-spatial frequency errors in a compact package. In this paper we discuss recent development of adaptive x-ray optics at AOA-Xinetics.

  10. Industrial applications of fiber optic sensing

    NASA Astrophysics Data System (ADS)

    Desforges, Francois X.; Blocksidge, Robert

    1996-08-01

    Thanks to the growth of the fiber optics telecommunication industry, fiber optic components have become less expensive, more reliable and well known by potential fiber optic sensor users. LEDs, optical fibers, couplers and connectors are now widely distributed and are the building blocks for the fiber optic sensor manufacturer. Additionally, the huge demand in consumer electronics of the past 10 years has provided the manufacturer with cheap and powerful programmable logic components which reduce the development time as well as the cost of the associated instrumentation. This market trend has allowed Photonetics to develop, manufacture and sell fiber optic sensors for the last 10 years. The company contribution in the fields of fiber optic gyros (4 licenses sold world wide), white light interferometry and fiber optic sensor networks is widely recognized. Moreover, its 1992 acquisition of some of the assets of Metricor Inc., greatly reinforced its position and allowed it to pursue new markets. Over the past four years, Photonetics has done an important marketing effort to better understand the need of its customers. The result of this research has fed R&D efforts towards a new generation instrument, the Metricor 2000, better adapted to the expectations of fiber optic sensors users, thanks to its unique features: (1) universality -- the system can accept more than 20 different sensors (T, P, RI, . . .). (2) scalability -- depending on the customer needs, the system can be used with 1 to 64 sensors. (3) performance -- because of its improved design, overall accuracies of 0.01% FS can be reached. (4) versatility -- its modular design enables a fast and easy custom design for specific applications. This paper presents briefly the Metricor 2000 and its family of FO probes. Then, it describes two fiber optic sensing (FOS) applications/markets where FOS have proven to be very useful.

  11. Testing the Apodized Pupil Lyot Coronagraph on the Laboratory for Adaptive Optics Extreme Adaptive Optics Testbed

    NASA Astrophysics Data System (ADS)

    Thomas, Sandrine J.; Soummer, Rémi; Dillon, Daren; Macintosh, Bruce; Gavel, Donald; Sivaramakrishnan, Anand

    2011-10-01

    We present testbed results of the Apodized Pupil Lyot Coronagraph (APLC) at the Laboratory for Adaptive Optics (LAO). These results are part of the validation and tests of the coronagraph and of the Extreme Adaptive Optics (ExAO) for the Gemini Planet Imager (GPI). The apodizer component is manufactured with a halftone technique using black chrome microdots on glass. Testing this APLC (like any other coronagraph) requires extremely good wavefront correction, which is obtained to the 1 nm rms level using the microelectricalmechanical systems (MEMS) technology, on the ExAO visible testbed of the LAO at the University of Santa Cruz. We used an APLC coronagraph without central obstruction, both with a reference super-polished flat mirror and with the MEMS to obtain one of the first images of a dark zone in a coronagraphic image with classical adaptive optics using a MEMS deformable mirror (without involving dark hole algorithms). This was done as a complementary test to the GPI coronagraph testbed at American Museum of Natural History, which studied the coronagraph itself without wavefront correction. Because we needed a full aperture, the coronagraph design is very different from the GPI design. We also tested a coronagraph with central obstruction similar to that of GPI. We investigated the performance of the APLC coronagraph and more particularly the effect of the apodizer profile accuracy on the contrast. Finally, we compared the resulting contrast to predictions made with a wavefront propagation model of the testbed to understand the effects of phase and amplitude errors on the final contrast.

  12. TESTING THE APODIZED PUPIL LYOT CORONAGRAPH ON THE LABORATORY FOR ADAPTIVE OPTICS EXTREME ADAPTIVE OPTICS TESTBED

    SciTech Connect

    Thomas, Sandrine J.; Dillon, Daren; Gavel, Donald; Macintosh, Bruce; Sivaramakrishnan, Anand E-mail: dillon@ucolick.org E-mail: soummer@stsci.edu E-mail: anand@amnh.org

    2011-10-15

    We present testbed results of the Apodized Pupil Lyot Coronagraph (APLC) at the Laboratory for Adaptive Optics (LAO). These results are part of the validation and tests of the coronagraph and of the Extreme Adaptive Optics (ExAO) for the Gemini Planet Imager (GPI). The apodizer component is manufactured with a halftone technique using black chrome microdots on glass. Testing this APLC (like any other coronagraph) requires extremely good wavefront correction, which is obtained to the 1 nm rms level using the microelectricalmechanical systems (MEMS) technology, on the ExAO visible testbed of the LAO at the University of Santa Cruz. We used an APLC coronagraph without central obstruction, both with a reference super-polished flat mirror and with the MEMS to obtain one of the first images of a dark zone in a coronagraphic image with classical adaptive optics using a MEMS deformable mirror (without involving dark hole algorithms). This was done as a complementary test to the GPI coronagraph testbed at American Museum of Natural History, which studied the coronagraph itself without wavefront correction. Because we needed a full aperture, the coronagraph design is very different from the GPI design. We also tested a coronagraph with central obstruction similar to that of GPI. We investigated the performance of the APLC coronagraph and more particularly the effect of the apodizer profile accuracy on the contrast. Finally, we compared the resulting contrast to predictions made with a wavefront propagation model of the testbed to understand the effects of phase and amplitude errors on the final contrast.

  13. Design and performance optimization of fiber optic adaptive filters

    NASA Astrophysics Data System (ADS)

    Paparao, Palacharla; Ghosh, Anjan; Allen, Susan D.

    1991-05-01

    The design of the least-mean-square algorithm-based fiber optic adaptive filters for processing guided lightwave signals in real time is described. Fiber optic adaptive filters can learn to change their parameters or to process a set of characteristics of the input signal. The realization employs as few electronic devices as possible and uses optical computation to utilize the advantages of optics in the processing speed, parallelism, and interconnection. The convergence or learning characteristics of the adaptive filtering process are analyzed as a function of the filter parameters and the fiber optic hardware errors. From this analysis it is found that the effects of the optical round-off errors and noise can be reduced, and the learning speed can be comparatively increased through an optimal selection of the filter parameters.

  14. Pulse front adaptive optics in two-photon microscopy.

    PubMed

    Sun, Bangshan; Salter, Patrick S; Booth, Martin J

    2015-11-01

    Adaptive optics has been extensively studied for the correction of phase front aberrations in optical systems. In systems using ultrafast lasers, distortions can also exist in the pulse front (contour of constant intensity in space and time), but until now their correction has been mostly unexplored due to technological limitations. In this Letter, we apply newly developed pulse front adaptive optics, for the first time to our knowledge, to practical compensation of a two-photon fluorescence microscope. With adaptive correction of the system-induced pulse front distortion, improvements beyond conventional phase correction are demonstrated.

  15. Adaptive optics parallel near-confocal scanning ophthalmoscopy.

    PubMed

    Lu, Jing; Gu, Boyu; Wang, Xiaolin; Zhang, Yuhua

    2016-08-15

    We present an adaptive optics parallel near-confocal scanning ophthalmoscope (AOPCSO) using a digital micromirror device (DMD). The imaging light is modulated to be a line of point sources by the DMD, illuminating the retina simultaneously. By using a high-speed line camera to acquire the image and using adaptive optics to compensate the ocular wave aberration, the AOPCSO can image the living human eye with cellular level resolution at the frame rate of 100 Hz. AOPCSO has been demonstrated with improved spatial resolution in imaging of the living human retina compared with adaptive optics line scan ophthalmoscopy.

  16. Adaptive Optics Parallel Near-Confocal Scanning Ophthalmoscopy

    PubMed Central

    Lu, Jing; Gu, Boyu; Wang, Xiaolin; Zhang, Yuhua

    2016-01-01

    We present an adaptive optics parallel confocal scanning ophthalmoscope (AOPCSO) using a digital micromirror device (DMD). The imaging light is modulated to be a line of point sources by the DMD, illuminating the retina simultaneously. By using a high speed line camera to acquire the image and using adaptive optics to compensate ocular wave aberration, the AOPCSO can image the living human eye with cellular level resolution at the frame rate of 100 Hz. AOPCSO has been demonstrated with improved spatial resolution in imaging of the living human retina compared with adaptive optics line scan ophthalmoscopy. PMID:27519106

  17. Adaptive wide-field optical tomography

    NASA Astrophysics Data System (ADS)

    Venugopal, Vivek; Intes, Xavier

    2013-03-01

    We describe a wide-field optical tomography technique, which allows the measurement-guided optimization of illumination patterns for enhanced reconstruction performances. The iterative optimization of the excitation pattern aims at reducing the dynamic range in photons transmitted through biological tissue. It increases the number of measurements collected with high photon counts resulting in a dataset with improved tomographic information. Herein, this imaging technique is applied to time-resolved fluorescence molecular tomography for preclinical studies. First, the merit of this approach is tested by in silico studies in a synthetic small animal model for typical illumination patterns. Second, the applicability of this approach in tomographic imaging is validated in vitro using a small animal phantom with two fluorescent capillaries occluded by a highly absorbing inclusion. The simulation study demonstrates an improvement of signal transmitted (˜2 orders of magnitude) through the central portion of the small animal model for all patterns considered. A corresponding improvement in the signal at the emission wavelength by 1.6 orders of magnitude demonstrates the applicability of this technique for fluorescence molecular tomography. The successful discrimination and localization (˜1 mm error) of the two objects with higher resolution using the optimized patterns compared with nonoptimized illumination establishes the improvement in reconstruction performance when using this technique.

  18. Simulating Astronomical Adaptive Optics Systems Using Yao

    NASA Astrophysics Data System (ADS)

    Rigaut, François; Van Dam, Marcos

    2013-12-01

    Adaptive Optics systems are at the heart of the coming Extremely Large Telescopes generation. Given the importance, complexity and required advances of these systems, being able to simulate them faithfully is key to their success, and thus to the success of the ELTs. The type of systems envisioned to be built for the ELTs cover most of the AO breeds, from NGS AO to multiple guide star Ground Layer, Laser Tomography and Multi-Conjugate AO systems, with typically a few thousand actuators. This represents a large step up from the current generation of AO systems, and accordingly a challenge for existing AO simulation packages. This is especially true as, in the past years, computer power has not been following Moore's law in its most common understanding; CPU clocks are hovering at about 3GHz. Although the use of super computers is a possible solution to run these simulations, being able to use smaller machines has obvious advantages: cost, access, environmental issues. By using optimised code in an already proven AO simulation platform, we were able to run complex ELT AO simulations on very modest machines, including laptops. The platform is YAO. In this paper, we describe YAO, its architecture, its capabilities, the ELT-specific challenges and optimisations, and finally its performance. As an example, execution speed ranges from 5 iterations per second for a 6 LGS 60x60 subapertures Shack-Hartmann Wavefront sensor Laser Tomography AO system (including full physical image formation and detector characteristics) up to over 30 iterations/s for a single NGS AO system.

  19. Isoplanatism in a multiconjugate adaptive optics system.

    PubMed

    Tokovinin, A; Le Louarn, M; Sarazin, M

    2000-10-01

    Turbulence correction in a large field of view by use of an adaptive optics imaging system with several deformable mirrors (DM's) conjugated to various heights is considered. The residual phase variance is computed for an optimized linear algorithm in which a correction of each turbulent layer is achieved by applying a combination of suitably smoothed and scaled input phase screens to all DM's. Finite turbulence outer scale and finite spatial resolution of the DM's are taken into account. A general expression for the isoplanatic angle thetaM of a system with M mirrors is derived in the limiting case of infinitely large apertures and Kolmogorov turbulence. Like Fried's isoplanatic angle theta0,thetaM is a function only of the turbulence vertical profile, is scalable with wavelength, and is independent of the telescope diameter. Use of angle thetaM permits the gain in the field of view due to the increased number of DM's to be quantified and their optimal conjugate heights to be found. Calculations with real turbulence profiles show that with three DM's a gain of 7-10x is possible, giving the typical and best isoplanatic field-of-view radii of 16 and 30 arcseconds, respectively, at lambda = 0.5 microm. It is shown that in the actual systems the isoplanatic field will be somewhat larger than thetaM owing to the combined effects of finite aperture diameter, finite outer scale, and optimized wave-front spatial filtering. However, this additional gain is not dramatic; it is less than 1.5x for large-aperture telescopes.

  20. Sensorless adaptive optics implementation in widefield optical sectioning microscopy inside in vivo Drosophila brain

    NASA Astrophysics Data System (ADS)

    Pedrazzani, Mélanie; Loriette, Vincent; Tchenio, Paul; Benrezzak, Sakina; Nutarelli, Daniele; Fragola, Alexandra

    2016-03-01

    We present an implementation of a sensorless adaptive optics loop in a widefield fluorescence microscope. This setup is designed to compensate for aberrations induced by the sample on both excitation and emission pathways. It allows fast optical sectioning inside a living Drosophila brain. We present a detailed characterization of the system performances. We prove that the gain brought to optical sectioning by realizing structured illumination microscopy with adaptive optics down to 50 μm deep inside living Drosophila brain.

  1. Sensorless adaptive optics implementation in widefield optical sectioning microscopy inside in vivo Drosophila brain.

    PubMed

    Pedrazzani, Mélanie; Loriette, Vincent; Tchenio, Paul; Benrezzak, Sakina; Nutarelli, Daniele; Fragola, Alexandra

    2016-03-01

    We present an implementation of a sensorless adaptive optics loop in a widefield fluorescence microscope. This setup is designed to compensate for aberrations induced by the sample on both excitation and emission pathways. It allows fast optical sectioning inside a living Drosophila brain. We present a detailed characterization of the system performances. We prove that the gain brought to optical sectioning by realizing structured illumination microscopy with adaptive optics down to 50 μm deep inside living Drosophila brain.

  2. Optimal control law for classical and multiconjugate adaptive optics.

    PubMed

    Le Roux, Brice; Conan, Jean-Marc; Kulcsár, Caroline; Raynaud, Henri-François; Mugnier, Laurent M; Fusco, Thierry

    2004-07-01

    Classical adaptive optics (AO) is now a widespread technique for high-resolution imaging with astronomical ground-based telescopes. It generally uses simple and efficient control algorithms. Multiconjugate adaptive optics (MCAO) is a more recent and very promising technique that should extend the corrected field of view. This technique has not yet been experimentally validated, but simulations already show its high potential. The importance for MCAO of an optimal reconstruction using turbulence spatial statistics has already been demonstrated through open-loop simulations. We propose an optimal closed-loop control law that accounts for both spatial and temporal statistics. The prior information on the turbulence, as well as on the wave-front sensing noise, is expressed in a state-space model. The optimal phase estimation is then given by a Kalman filter. The equations describing the system are given and the underlying assumptions explained. The control law is then derived. The gain brought by this approach is demonstrated through MCAO numerical simulations representative of astronomical observation on a 8-m-class telescope in the near infrared. We also discuss the application of this control approach to classical AO. Even in classical AO, the technique could be relevant especially for future extreme AO systems.

  3. Polycapillary optics for medical applications

    NASA Astrophysics Data System (ADS)

    MacDonald, C. A.; Petruccelli, J. C.

    2016-11-01

    Polycapillary optics can be designed for a wide variety of x-ray applications, including x-ray fluorescence for non-destructive materials analysis and diffraction applications such as protein crystallography. Of particular interest are medical applications, including the removal of Compton scattering with the resultant improvement in contrast and resolution in mammography, the production of monochromatic parallel beams for high-contrast imaging in clinical settings and the localization of radioactive tracers. A recent development is the use of polycapillary optics to improve beam coherence for x-ray phase imaging. Conventional radiographic techniques depend on attenuation, which provides only low contrast between soft tissues. Phase imaging can yield significantly higher contrast but requires spatially coherent beams. Conventional sources small enough to produce high coherence are necessarily low power, requiring long exposures. Polycapillary optics employed to create a small secondary source from high power sources have been shown to yield strong phase effects. Polycapillary optics can also be combined with other x-ray optics. A combination of a toroidally bent crystal with a polycapillary optic has been shown to produce enhanced resolution in a magnified image. Another x-ray imaging technique which does not rely on the small attenuation contrast is the capture of coherently scattered radiation, for which polycapillary optics could be used as angular filters to collect the beam, resulting in a map of tissue or material type.

  4. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging

    PubMed Central

    Cua, Michelle; Wahl, Daniel J.; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J.; Jian, Yifan; Sarunic, Marinko V.

    2016-01-01

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems. PMID:27599635

  5. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging

    NASA Astrophysics Data System (ADS)

    Cua, Michelle; Wahl, Daniel J.; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J.; Jian, Yifan; Sarunic, Marinko V.

    2016-09-01

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems.

  6. Coherence-Gated Sensorless Adaptive Optics Multiphoton Retinal Imaging.

    PubMed

    Cua, Michelle; Wahl, Daniel J; Zhao, Yuan; Lee, Sujin; Bonora, Stefano; Zawadzki, Robert J; Jian, Yifan; Sarunic, Marinko V

    2016-09-07

    Multiphoton microscopy enables imaging deep into scattering tissues. The efficient generation of non-linear optical effects is related to both the pulse duration (typically on the order of femtoseconds) and the size of the focused spot. Aberrations introduced by refractive index inhomogeneity in the sample distort the wavefront and enlarge the focal spot, which reduces the multiphoton signal. Traditional approaches to adaptive optics wavefront correction are not effective in thick or multi-layered scattering media. In this report, we present sensorless adaptive optics (SAO) using low-coherence interferometric detection of the excitation light for depth-resolved aberration correction of two-photon excited fluorescence (TPEF) in biological tissue. We demonstrate coherence-gated SAO TPEF using a transmissive multi-actuator adaptive lens for in vivo imaging in a mouse retina. This configuration has significant potential for reducing the laser power required for adaptive optics multiphoton imaging, and for facilitating integration with existing systems.

  7. Wavefront sensors for adaptive optical systems

    NASA Astrophysics Data System (ADS)

    Lukin, V. P.; Botygina, N. N.; Emaleev, O. N.; Konyaev, P. A.

    2010-01-01

    A high precision Shack-Hartmann wavefront (WF) sensor has been developed on the basis of a low-aperture off-axis diffraction lens array. The device is capable of measuring WF slopes at array sub-apertures of 640x640 μm in size with an error not exceeding 4.80 arcsec (0.15 pixel), which corresponds to the standard deviation equal to 0.017 λ at the reconstructed WF with wavelength λ. Also the modification of this sensor for adaptive system of solar telescope using extended scenes as tracking objects, such as sunspot, pores, solar granulation and limb, is presented. The software package developed for the proposed WF sensors includes three algorithms of local WF slope estimation (modified centroids, normalized cross-correlation and fast Fourier-demodulation), as well as three methods of WF reconstruction (modal Zernike polynomial expansion, deformable mirror response function expansion and phase unwrapping), that can be selected during operation with accordance to the application.

  8. Wavefront sensors for adaptive optical systems

    NASA Astrophysics Data System (ADS)

    Lukin, V. P.; Botygina, N. N.; Emaleev, O. N.; Konyaev, P. A.

    2010-10-01

    A high precision Shack-Hartmann wavefront (WF) sensor has been developed on the basis of a low-aperture off-axis diffraction lens array. The device is capable of measuring WF slopes at array sub-apertures of size 640x640 μm with an error not exceeding 4.80 arcsec (0.15 pixel), which corresponds to the standard deviation equal to 0.017λ at the reconstructed WF with wavelength λ . Also the modification of this sensor for adaptive system of solar telescope using extended scenes as tracking objects, such as sunspot, pores, solar granulation and limb, is presented. The software package developed for the proposed WF sensors includes three algorithms of local WF slopes estimation (modified centroids, normalized cross-correlation and fast Fourier-demodulation), as well as three methods of WF reconstruction (modal Zernike polynomials expansion, deformable mirror response functions expansion and phase unwrapping), that can be selected during operation with accordance to the application.

  9. Solar adaptive optics: specificities, lessons learned, and open alternatives

    NASA Astrophysics Data System (ADS)

    Montilla, I.; Marino, J.; Asensio Ramos, A.; Collados, M.; Montoya, L.; Tallon, M.

    2016-07-01

    First on sky adaptive optics experiments were performed on the Dunn Solar Telescope on 1979, with a shearing interferometer and limited success. Those early solar adaptive optics efforts forced to custom-develop many components, such as Deformable Mirrors and WaveFront Sensors, which were not available at that time. Later on, the development of the correlation Shack-Hartmann marked a breakthrough in solar adaptive optics. Since then, successful Single Conjugate Adaptive Optics instruments have been developed for many solar telescopes, i.e. the National Solar Observatory, the Vacuum Tower Telescope and the Swedish Solar Telescope. Success with the Multi Conjugate Adaptive Optics systems for GREGOR and the New Solar Telescope has proved to be more difficult to attain. Such systems have a complexity not only related to the number of degrees of freedom, but also related to the specificities of the Sun, used as reference, and the sensing method. The wavefront sensing is performed using correlations on images with a field of view of 10", averaging wavefront information from different sky directions, affecting the sensing and sampling of high altitude turbulence. Also due to the low elevation at which solar observations are performed we have to include generalized fitting error and anisoplanatism, as described by Ragazzoni and Rigaut, as non-negligible error sources in the Multi Conjugate Adaptive Optics error budget. For the development of the next generation Multi Conjugate Adaptive Optics systems for the Daniel K. Inouye Solar Telescope and the European Solar Telescope we still need to study and understand these issues, to predict realistically the quality of the achievable reconstruction. To improve their designs other open issues have to be assessed, i.e. possible alternative sensing methods to avoid the intrinsic anisoplanatism of the wide field correlation Shack-Hartmann, new parameters to estimate the performance of an adaptive optics solar system, alternatives to

  10. Based on ground station adaptive optics for laser communications demonstration platform structures

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Tong, Shoufeng; Wang, Haozeng; Yang, Hongkun

    2013-08-01

    With the rapid development of modern science and technology in astronomical imaging, optical communications, optical radar, optical information processing, high-precision ranging, tracking, guidance, and remote sensing, light waves propagating in the medium, especially in the turbulent atmosphere spread more and more important. Atmospheric turbulence is one of the main factors which have influence on the performance of a laser communication system. Adaptive optics technology is an important means to solve the problem of atmospheric turbulence. This paper states how adaptive optics technique can be used in space laser communication system to compensate atmospheric turbulence when laser beam transmission through it. The core content of adaptive optics is correct laser beam wave-front disturbance in real-time,with it to enhance optical system imaging quality and the next aim is reach the level of diffraction limitation. Adaptive optics system consists of wave-front detection, wave-front control and wave-front correction . The demo platform including: atmospheric turbulence simulation unit、adaptive correction unit、signal transmitting and receiving unit. Liquid crystal spatial light modulator applications in adaptive optics system and the turbulence simulation system introduced. And used zernike polynomials method to produce atmospheric turbulence phase screen simulation analysis. Simulation results show that: in the low spatial frequency components, the atmospheric turbulence phase screen generated by Zernike polynomial method consistent with the theoretical values, but in the high spatial frequency components, the simulation results with large difference between the theoretical values. In addition, the simulation results also show that: we can change the distribution of turbulence in the atmospheric turbulence phase screen by increasing the Zernike polynomials of orders or change the receiving apertures, but to calculate the large calculate the complex and

  11. How adaptive optics may have won the Cold War

    NASA Astrophysics Data System (ADS)

    Tyson, Robert K.

    2013-05-01

    While there are many theories and studies concerning the end of the Cold War, circa 1990, I postulate that one of the contributors to the result was the development of adaptive optics. The emergence of directed energy weapons, specifically space-based and ground-based high energy lasers made practicable with adaptive optics, showed that a successful defense against inter-continental ballistic missiles was not only possible, but achievable in a reasonable period of time.

  12. Laser guide star adaptive optics: Present and future

    SciTech Connect

    Olivier, S.S.; Max, C.E.

    1993-03-01

    Feasibility demonstrations using one to two meter telescopes have confirmed the utility of laser beacons as wavefront references for adaptive optics systems. Laser beacon architectures suitable for the new generation of eight and ten meter telescopes are presently under study. This paper reviews the concept of laser guide star adaptive optics and the progress that has been made by groups around the world implementing such systems. A description of the laser guide star program at LLNL and some experimental results is also presented.

  13. Solar adaptive optics at the Observatorio del Teide, Tenerife

    NASA Astrophysics Data System (ADS)

    Soltau, Dirk; Berkefeld, Thomas; Schmidt, Dirk; von der Lühe, Oskar

    2013-10-01

    Observing the Sun with high angular resolution is difficult because the turbulence in the atmosphere is strongest during day time. In this paper we describe the principles of solar adaptive optics exemplified by the two German solar telescopes VTT and GREGOR at the Observatorio del Teide. With theses systems we obtain near diffraction limited images of the Sun. Ways to overcome the limits of conventional AO by applying multiconjugate adaptive optics (MCAO) are shown.

  14. Guide star lasers for adaptive optics

    NASA Astrophysics Data System (ADS)

    Roberts, William Thomas, Jr.

    Exploitation of the imaging capabilities of the new generation of ground-based astronomical telescopes relies heavily on Adaptive Optics (AO). Current AO system designs call for sodium guide star lasers capable of producing at least eight Watts of power tuned to the peak of the sodium D2 line, with a high duty cycle to avoid saturation, and with 0.5-1.0 GHz spectral broadening. This work comprises development and testing of six candidate laser systems and materials which may afford a path to achieving these goals. An end-pumped CW dye laser producing 4.0 Watts of tuned output power was developed and used to obtain the first accurate measurement of sodium layer scattering efficiency. Methods of optimizing the laser output through improving pump overlap efficiency and reducing the number of intracavity scattering surfaces are covered. The 1181 nm fluorescence peak of Mn5+ ion in Ba5 (PO4)3Cl could be tuned and doubled to reach 589 nm. While efforts to grow this crystal were under way, the Mn5+ ion in natural apatite (Ca5(PO4)3F) was studied as a potential laser material. Fluorescence saturation measurements and transmission saturation are presented, as well as efforts to obtain CW lasing in natural apatite. A Q-switched laser color-center laser in LiF : F-2 was developed and successfully tuned and doubled to the sodium D 2 line. Broad-band lasing of 80 mW and tuned narrow-band lasing of 35 mW at 1178 nm were obtained with 275 mW of input pump power at 1064 nm. The measured thermal properties of this material indicate its potential for scaling to much higher power. A Q-switched intracavity Raman laser was developed in which CaWO 4 was used to shift a Nd:YAG laser, the frequency-doubled output of which was centered at 589.3 nm. To obtain light at 589.0 nm, a compositionally tuned pump laser of Nd : Y3Ga1.1Al3.9O 12 was produced which generated the desired shift, but was inhomogeneous broadened, limiting the tunable power of the material. Finally, temperature tuning of

  15. Adaptive optics and optical structures; Proceedings of the Meeting, European Congress on Optics, 3rd, The Hague, Netherlands, Mar. 12-14, 1990

    NASA Technical Reports Server (NTRS)

    Tyson, Robert K. (Editor); Schulte In Den Baeumen, J. (Editor)

    1990-01-01

    The present conference on adaptive optics (AO) and optical structures addresses AO systems and controls, AO components, nonlinear optics applications to AO, astronomical applications of AO, large telescopes and optical alignment, as well as the wavefront control experiment for the use of AO in beam propagation. Specific references are made to applications of electromagnetic theory in optics, theoretical studies of system performance and design parameters, Hartmann-Shack wavefront sensing, the use of ray-based techniques in cophasing segmented mirrors, the use of a phase-conjugating mirror for real-time phase visualization, and the absolute instability of oppositely directed waves with respect to a high-reflectivity phase-conjugate mirror. Also addressed are automatic control systems, precision segmented reflectors, AO system creation, the VLT's 8.2-m primary mirrors, an optical 12-m telescope, alignment optimization via the Talbot effect, and a combination of interferometry and ray-tracing analysis.

  16. Wavefront sensors and algorithms for adaptive optical systems

    NASA Astrophysics Data System (ADS)

    Lukin, V. P.; Botygina, N. N.; Emaleev, O. N.; Konyaev, P. A.

    2010-07-01

    The results of recent works related to techniques and algorithms for wave-front (WF) measurement using Shack-Hartmann sensors show their high efficiency in solution of very different problems of applied optics. The goal of this paper was to develop a sensitive Shack-Hartmann sensor with high precision WF measurement capability on the base of modern technology of optical elements making and new efficient methods and computational algorithms of WF reconstruction. The Shack-Hartmann sensors sensitive to small WF aberrations are used for adaptive optical systems, compensating the wave distortions caused by atmospheric turbulence. A high precision Shack-Hartmann WF sensor has been developed on the basis of a low-aperture off-axis diffraction lens array. The device is capable of measuring WF slopes at array sub-apertures of size 640×640 μm with an error not exceeding 4.80 arcsec (0.15 pixel), which corresponds to the standard deviation equal to 0.017λ at the reconstructed WF with wavelength λ . Also the modification of this sensor for adaptive system of solar telescope using extended scenes as tracking objects, such as sunspot, pores, solar granulation and limb, is presented. The software package developed for the proposed WF sensors includes three algorithms of local WF slopes estimation (modified centroids, normalized cross-correlation and fast Fourierdemodulation), as well as three methods of WF reconstruction (modal Zernike polynomials expansion, deformable mirror response functions expansion and phase unwrapping), that can be selected during operation with accordance to the application.

  17. Adaptive optics in digital micromirror based confocal microscopy

    NASA Astrophysics Data System (ADS)

    Pozzi, P.; Wilding, D.; Soloviev, O.; Vdovin, G.; Verhaegen, M.

    2016-03-01

    This proceeding reports early results in the development of a new technique for adaptive optics in confocal microscopy. The term adaptive optics refers to the branch of optics in which an active element in the optical system is used to correct inhomogeneities in the media through which light propagates. In its most classical form, mostly used in astronomical imaging, adaptive optics is achieved through a closed loop in which the actuators of a deformable mirror are driven by a wavefront sensor. This approach is severely limited in fluorescence microscopy, as the use of a wavefront sensor requires the presence of a bright, point like source in the field of view, a condition rarely satisfied in microscopy samples. Previously reported approaches to adaptive optics in fluorescence microscopy are therefore limited to the inclusion of fluorescent microspheres in the sample, to use as bright stars for wavefront sensors, or time consuming sensorless optimization procedures, requiring several seconds of optimization before the acquisition of a single image. We propose an alternative approach to the problem, implementing sensorless adaptive optics in a Programmable array microscope. A programmable array microscope is a microscope based on a digital micromirror device, in which the single elements of the micromirror act both as point sources and pinholes.

  18. Adaptive optics scanning laser ophthalmoscope imaging: technology update

    PubMed Central

    Merino, David; Loza-Alvarez, Pablo

    2016-01-01

    Adaptive optics (AO) retinal imaging has become very popular in the past few years, especially within the ophthalmic research community. Several different retinal techniques, such as fundus imaging cameras or optical coherence tomography systems, have been coupled with AO in order to produce impressive images showing individual cell mosaics over different layers of the in vivo human retina. The combination of AO with scanning laser ophthalmoscopy has been extensively used to generate impressive images of the human retina with unprecedented resolution, showing individual photoreceptor cells, retinal pigment epithelium cells, as well as microscopic capillary vessels, or the nerve fiber layer. Over the past few years, the technique has evolved to develop several different applications not only in the clinic but also in different animal models, thanks to technological developments in the field. These developments have specific applications to different fields of investigation, which are not limited to the study of retinal diseases but also to the understanding of the retinal function and vision science. This review is an attempt to summarize these developments in an understandable and brief manner in order to guide the reader into the possibilities that AO scanning laser ophthalmoscopy offers, as well as its limitations, which should be taken into account when planning on using it. PMID:27175057

  19. Wavefront Reconstruction and Mirror Surface Optimizationfor Adaptive Optics

    DTIC Science & Technology

    2014-06-01

    TERMS Wavefront reconstruction, Adaptive optics, Wavelets, Atmospheric turbulence, Branch points, Mirror surface optimization, Space telescope , Segmented...artist rendition of the James Webb Space Telescope . . . . . . . . . . . . . . . . 4 Figure 2.1 Example of upsampling and downsampling a signal...optics, structures, and controls to make a functional telescope . Space -based telescope designs now incorporate segmented mirror technology. For exam

  20. Digital holographic adaptive optics for ocular imaging: proof of principle.

    PubMed

    Liu, Changgeng; Kim, Myung K

    2011-07-15

    An adaptive optics (AO) ocular imaging system is proposed that is based on the principles of digital holography and dispenses with the wavefront sensor and wavefront modulator of conventional AO systems, thus reducing the optomechanical complexity and cost while increasing speed and resolution. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility. © 2011 Optical Society of America

  1. Reliability of MEMS deformable mirror technology used in adaptive optics imaging systems

    NASA Astrophysics Data System (ADS)

    Hartzell, Allyson L.; Cornelissen, Steven A.; Bierden, Paul A.; Lam, Charlie V.; Davis, Daniel F.

    2010-02-01

    Deformable mirror (DM) technology based on microelectromechanical systems (MEMS) technology produced by Boston Micromachines Corporation has been demonstrated to be an enabling component in a variety of adaptive optics applications such as high contrast imaging in astronomy, multi object adaptive optics, free-space laser communication, and microscopy. Many of these applications require DMs with thousands of actuators operating at frame rates up to 10 kHz for many years requiring sufficient device reliability to avoid device failures. In this paper we present improvements in MEMS deformable mirrors for reliability along with test data and device lifetime prediction that show trillions of actuator-cycles can be achieved without failures.

  2. Implementing Adaptive Performance Management in Server Applications

    SciTech Connect

    Liu, Yan; Gorton, Ian

    2007-06-11

    Performance and scalability are critical quality attributes for server applications in Internet-facing business systems. These applications operate in dynamic environments with rapidly fluctuating user loads and resource levels, and unpredictable system faults. Adaptive (autonomic) systems research aims to augment such server applications with intelligent control logic that can detect and react to sudden environmental changes. However, developing this adaptive logic is complex in itself. In addition, executing the adaptive logic consumes processing resources, and hence may (paradoxically) adversely affect application performance. In this paper we describe an approach for developing high-performance adaptive server applications and the supporting technology. The Adaptive Server Framework (ASF) is built on standard middleware services, and can be used to augment legacy systems with adaptive behavior without needing to change the application business logic. Crucially, ASF provides built-in control loop components to optimize the overall application performance, which comprises both the business and adaptive logic. The control loop is based on performance models and allows systems designers to tune the performance levels simply by modifying high level declarative policies. We demonstrate the use of ASF in a case study.

  3. Adaptive mode control in few mode fibers and its applications

    NASA Astrophysics Data System (ADS)

    Ashry, Islam; Lu, Peng; Xu, Yong

    2016-10-01

    With the development of mode-division-multiplexing (MDM), few mode fibers (FMFs) have found a wide range of applications in optical sensing and communications. However, how to precisely control the mode composition of optical signals in FMFs remains a difficult challenge. In this paper, we present an adaptive mode control method that can selectively excite the linearly polarized (LP) mode within the FMF. The method is based on using optical pulses reflected by a fiber Bragg grating (FBG) for wavefront optimization. Two potential applications are discussed. First, we theoretically demonstrate the feasibility of large scale multiplexing of absorption based fiber optical sensors. Second, we discuss the possibility of using mode dependent loss to reconstruct the spatial distributions of absorptive chemicals diffused within a FMF.

  4. Retinal imaging with a combined adaptive optics/optical coherence tomography and adaptive optics/scanning laser ophthalmoscopy system

    NASA Astrophysics Data System (ADS)

    Zawadzki, Robert J.; Jones, Steven M.; Pilli, Suman; Kim, Dae Yu; Olivier, Scot S.; Werner, John S.

    2010-02-01

    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.

  5. Meaning of visualizing retinal cone mosaic on adaptive optics images.

    PubMed

    Jacob, Julie; Paques, Michel; Krivosic, Valérie; Dupas, Bénédicte; Couturier, Aude; Kulcsar, Caroline; Tadayoni, Ramin; Massin, Pascale; Gaudric, Alain

    2015-01-01

    To explore the anatomic correlation of the retinal cone mosaic on adaptive optics images. Retrospective nonconsecutive observational case series. A retrospective review of the multimodal imaging charts of 6 patients with focal alteration of the cone mosaic on adaptive optics was performed. Retinal diseases included acute posterior multifocal placoid pigment epitheliopathy (n = 1), hydroxychloroquine retinopathy (n = 1), and macular telangiectasia type 2 (n = 4). High-resolution retinal images were obtained using a flood-illumination adaptive optics camera. Images were recorded using standard imaging modalities: color and red-free fundus camera photography; infrared reflectance scanning laser ophthalmoscopy, fluorescein angiography, indocyanine green angiography, and spectral-domain optical coherence tomography (OCT) images. On OCT, in the marginal zone of the lesions, a disappearance of the interdigitation zone was observed, while the ellipsoid zone was preserved. Image recording demonstrated that such attenuation of the interdigitation zone co-localized with the disappearance of the cone mosaic on adaptive optics images. In 1 case, the restoration of the interdigitation zone paralleled that of the cone mosaic after a 2-month follow-up. Our results suggest that the interdigitation zone could contribute substantially to the reflectance of the cone photoreceptor mosaic. The absence of cones on adaptive optics images does not necessarily mean photoreceptor cell death. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Initial results from implementing and testing a MEMS adaptive optics system

    NASA Astrophysics Data System (ADS)

    Smith, Julie C.; Sanchez, Darryl J.; Oesch, Denis W.; Engstrom, Nathan; Arguello, Loretta; Tewksbury-Christle, Carolyn M.; Vitayaudom, Kevin P.; Kelly, Patrick R.

    2009-08-01

    This paper is the 3rd in a series of papers discussing characterization of a Micro-Electrical-Mechanical-System (MEMS) deformable mirror in adaptive optics. Here we present a comparison between a conventional adaptive optics system using a Xinetics continuous face sheet deformable mirror with that of segmented MEMS deformable mirror. We intentionally designed the optical layout to mimic that of a conventional adaptive optics system. We present this initial optical layout for the MEMS adaptive optics system and discuss problems incurred with implementing such a layout; also presented is an enhanced optical layout that partially addresses these problems. Closed loop Strehl highlighting the two systems will be shown for each case as well. Finally the performances of both conventional adaptive optics and the MEMS adaptive optics system is presented for a range of adaptive optics parameters pertinent to astronomical adaptive optics leading to a discussion of the possible implication of introducing a MEMS adaptive optics system into the science community.

  7. Amplitude variations on the Extreme Adaptive Optics testbed

    SciTech Connect

    Evans, J; Thomas, S; Dillon, D; Gavel, D; Phillion, D; Macintosh, B

    2007-08-14

    High-contrast adaptive optics systems, such as those needed to image extrasolar planets, are known to require excellent wavefront control and diffraction suppression. At the Laboratory for Adaptive Optics on the Extreme Adaptive Optics testbed, we have already demonstrated wavefront control of better than 1 nm rms within controllable spatial frequencies. Corresponding contrast measurements, however, are limited by amplitude variations, including those introduced by the micro-electrical-mechanical-systems (MEMS) deformable mirror. Results from experimental measurements and wave optic simulations of amplitude variations on the ExAO testbed are presented. We find systematic intensity variations of about 2% rms, and intensity variations with the MEMS to be 6%. Some errors are introduced by phase and amplitude mixing because the MEMS is not conjugate to the pupil, but independent measurements of MEMS reflectivity suggest that some error is introduced by small non-uniformities in the reflectivity.

  8. A dual-modal retinal imaging system with adaptive optics

    PubMed Central

    Meadway, Alexander; Girkin, Christopher A.; Zhang, Yuhua

    2013-01-01

    An adaptive optics scanning laser ophthalmoscope (AO-SLO) is adapted to provide optical coherence tomography (OCT) imaging. The AO-SLO function is unchanged. The system uses the same light source, scanning optics, and adaptive optics in both imaging modes. The result is a dual-modal system that can acquire retinal images in both en face and cross-section planes at the single cell level. A new spectral shaping method is developed to reduce the large sidelobes in the coherence profile of the OCT imaging when a non-ideal source is used with a minimal introduction of noise. The technique uses a combination of two existing digital techniques. The thickness and position of the traditionally named inner segment/outer segment junction are measured from individual photoreceptors. In-vivo images of healthy and diseased human retinas are demonstrated. PMID:24514529

  9. Wavefront sensorless adaptive optics ophthalmoscopy in the human eye

    PubMed Central

    Hofer, Heidi; Sredar, Nripun; Queener, Hope; Li, Chaohong; Porter, Jason

    2011-01-01

    Wavefront sensor noise and fidelity place a fundamental limit on achievable image quality in current adaptive optics ophthalmoscopes. Additionally, the wavefront sensor ‘beacon’ can interfere with visual experiments. We demonstrate real-time (25 Hz), wavefront sensorless adaptive optics imaging in the living human eye with image quality rivaling that of wavefront sensor based control in the same system. A stochastic parallel gradient descent algorithm directly optimized the mean intensity in retinal image frames acquired with a confocal adaptive optics scanning laser ophthalmoscope (AOSLO). When imaging through natural, undilated pupils, both control methods resulted in comparable mean image intensities. However, when imaging through dilated pupils, image intensity was generally higher following wavefront sensor-based control. Despite the typically reduced intensity, image contrast was higher, on average, with sensorless control. Wavefront sensorless control is a viable option for imaging the living human eye and future refinements of this technique may result in even greater optical gains. PMID:21934779

  10. Satellite Imaging with Adaptive Optics on a 1 M Telescope

    NASA Astrophysics Data System (ADS)

    Bennet, F.; Price, I.; Rigaut, F.; Copeland, M.

    2016-09-01

    The Research School of Astronomy and Astrophysics at the Mount Stromlo Observatory in Canberra, Australia, have been developing adaptive optic (AO) systems for space situational awareness applications. We report on the development and demonstration of an AO system for satellite imaging using a 1 m telescope. The system uses the orbiting object as a natural guide star to measure atmospheric turbulence, and a deformable mirror to provide an optical correction. The AO system utilised modern, high speed and low noise EMCCD technology on both the wavefront sensor and imaging camera to achieve high performance, achieving a Strehl ratio in excess of 30% at 870 nm. Images are post processed with lucky imaging algorithms to further improve the final image quality. We demonstrate the AO system on stellar targets and Iridium satellites, achieving a near diffraction limited full width at half maximum. A specialised realtime controller allows our system to achieve a bandwidth above 100 Hz, with the wavefront sensor and control loop running at 2 kHz. The AO systems we are developing show how ground-based optical sensors can be used to manage the space environment. AO imaging systems can be used for satellite surveillance, while laser ranging can be used to determine precise orbital data used in the critical conjunction analysis required to maintain a safe space environment. We have focused on making this system compact, expandable, and versatile. We are continuing to develop this platform for other space situational awareness applications such as geosynchronous satellite astrometry, space debris characterisation, satellite imaging, and ground-to-space laser communication.

  11. NAOMI - Adaptive Optics at the WHT

    NASA Astrophysics Data System (ADS)

    Benn, Chris R.; Els, Sebastian; Gregory, Tom; Söchting, Ilona; Østensen, Roy

    NAOMI is the AO system of the William Herschel Telescope on La Palma. It delivers near-diffraction-limited imaging in the IR, and a significantly improved PSF at optical wavelengths. The science instrumentation includes an IR imager (INGRID), an optical integral-field spectrograph (OASIS) and a coronograph which may be placed in the light path to either instrument. 19 science programmes were observed during 2002-3.

  12. Application of Fiber Optic Instrumentation

    NASA Technical Reports Server (NTRS)

    Richards, William Lance; Parker, Allen R., Jr.; Ko, William L.; Piazza, Anthony; Chan, Patrick

    2012-01-01

    Fiber optic sensing technology has emerged in recent years offering tremendous advantages over conventional aircraft instrumentation systems. The advantages of fiber optic sensors over their conventional counterparts are well established; they are lighter, smaller, and can provide enormous numbers of measurements at a fraction of the total sensor weight. After a brief overview of conventional and fiber-optic sensing technology, this paper presents an overview of the research that has been conducted at NASA Dryden Flight Research Center in recent years to advance this promising new technology. Research and development areas include system and algorithm development, sensor characterization and attachment, and real-time experimentally-derived parameter monitoring for ground- and flight-based applications. The vision of fiber optic smart structure technology is presented and its potential benefits to aerospace vehicles throughout the lifecycle, from preliminary design to final retirement, are presented.

  13. Designing and Generating Educational Adaptive Hypermedia Applications

    ERIC Educational Resources Information Center

    Retalis, Symeon; Papasalouros, Andreas

    2005-01-01

    Educational Adaptive Hypermedia Applications (EAHA) provide personalized views on the learning content to individual learners. They also offer adaptive sequencing (navigation) over the learning content based on rules that stem from the user model requirements and the instructional strategies. EAHA are gaining the focus of the research community as…

  14. Designing and Generating Educational Adaptive Hypermedia Applications

    ERIC Educational Resources Information Center

    Retalis, Symeon; Papasalouros, Andreas

    2005-01-01

    Educational Adaptive Hypermedia Applications (EAHA) provide personalized views on the learning content to individual learners. They also offer adaptive sequencing (navigation) over the learning content based on rules that stem from the user model requirements and the instructional strategies. EAHA are gaining the focus of the research community as…

  15. Digital adaptive optics line-scanning confocal imaging system

    PubMed Central

    Liu, Changgeng; Kim, Myung K.

    2015-01-01

    Abstract. A digital adaptive optics line-scanning confocal imaging (DAOLCI) system is proposed by applying digital holographic adaptive optics to a digital form of line-scanning confocal imaging system. In DAOLCI, each line scan is recorded by a digital hologram, which allows access to the complex optical field from one slice of the sample through digital holography. This complex optical field contains both the information of one slice of the sample and the optical aberration of the system, thus allowing us to compensate for the effect of the optical aberration, which can be sensed by a complex guide star hologram. After numerical aberration compensation, the corrected optical fields of a sequence of line scans are stitched into the final corrected confocal image. In DAOLCI, a numerical slit is applied to realize the confocality at the sensor end. The width of this slit can be adjusted to control the image contrast and speckle noise for scattering samples. DAOLCI dispenses with the hardware pieces, such as Shack–Hartmann wavefront sensor and deformable mirror, and the closed-loop feedbacks adopted in the conventional adaptive optics confocal imaging system, thus reducing the optomechanical complexity and cost. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility of this idea. PMID:26140334

  16. Digital adaptive optics line-scanning confocal imaging system.

    PubMed

    Liu, Changgeng; Kim, Myung K

    2015-01-01

    A digital adaptive optics line-scanning confocal imaging (DAOLCI) system is proposed by applying digital holographic adaptive optics to a digital form of line-scanning confocal imaging system. In DAOLCI, each line scan is recorded by a digital hologram, which allows access to the complex optical field from one slice of the sample through digital holography. This complex optical field contains both the information of one slice of the sample and the optical aberration of the system, thus allowing us to compensate for the effect of the optical aberration, which can be sensed by a complex guide star hologram. After numerical aberration compensation, the corrected optical fields of a sequence of line scans are stitched into the final corrected confocal image. In DAOLCI, a numerical slit is applied to realize the confocality at the sensor end. The width of this slit can be adjusted to control the image contrast and speckle noise for scattering samples. DAOLCI dispenses with the hardware pieces, such as Shack–Hartmann wavefront sensor and deformable mirror, and the closed-loop feedbacks adopted in the conventional adaptive optics confocal imaging system, thus reducing the optomechanical complexity and cost. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility of this idea.

  17. Digital adaptive optics line-scanning confocal imaging system

    NASA Astrophysics Data System (ADS)

    Liu, Changgeng; Kim, Myung K.

    2015-11-01

    A digital adaptive optics line-scanning confocal imaging (DAOLCI) system is proposed by applying digital holographic adaptive optics to a digital form of line-scanning confocal imaging system. In DAOLCI, each line scan is recorded by a digital hologram, which allows access to the complex optical field from one slice of the sample through digital holography. This complex optical field contains both the information of one slice of the sample and the optical aberration of the system, thus allowing us to compensate for the effect of the optical aberration, which can be sensed by a complex guide star hologram. After numerical aberration compensation, the corrected optical fields of a sequence of line scans are stitched into the final corrected confocal image. In DAOLCI, a numerical slit is applied to realize the confocality at the sensor end. The width of this slit can be adjusted to control the image contrast and speckle noise for scattering samples. DAOLCI dispenses with the hardware pieces, such as Shack-Hartmann wavefront sensor and deformable mirror, and the closed-loop feedbacks adopted in the conventional adaptive optics confocal imaging system, thus reducing the optomechanical complexity and cost. Numerical simulations and proof-of-principle experiments are presented that demonstrate the feasibility of this idea.

  18. Optical Disc Applications in Libraries.

    ERIC Educational Resources Information Center

    Andre, Pamela Q. J.

    1989-01-01

    Discusses a variety of library applications of optical disc storage technology, including CD-ROM, digital videodisc, and WORM. Research and development projects at the Library of Congress, National Library of Medicine, and National Agricultural Library are described, products offered by library networks are reviewed, and activities in academic and…

  19. High resolution retinal imaging with a compact adaptive optics spectral domain optical coherence tomography system

    NASA Astrophysics Data System (ADS)

    Hammer, Daniel X.; Iftimia, Nicusor V.; Bigelow, Chad E.; Ustun, Teoman E.; Bloom, Benjamin; Ferguson, R. Daniel; Burns, Stephen A.

    2007-02-01

    Adaptive optics (AO) is used to correct ocular aberrations primarily in the cornea, lens, and tear film of every eye. Among other applications, AO allows high lateral resolution images to be acquired with scanning laser ophthalmoscopy (SLO) and optical coherence tomography (OCT). Spectral domain optical coherence tomography (SDOCT) is a high-speed imaging technique that can acquire cross-sectional scans with micron-scale axial resolution at tens to hundreds of kHz line rates. We present a compact clinical AO-SDOCT system that achieves micron-scale axial and lateral resolution of retinal structures. The system includes a line scanning laser ophthalmscope (LSLO) for simultaneous wide-field retinal viewing and selection of regions-of-interest. OCT and LSLO imaging and AO correction performance are characterized. We present a case study of a single subject with hyper-reflective lesions associated with stable, resolved central serous retinopathy to compare and contrast AO as applied to scanning laser ophthalmoscopy and optical coherence tomography. The two imaging modes are found to be complementary in terms of information on structure morphology. Both provide additional information lacking in the other. This preliminary finding points to the power of combining SLO and SDOCT in a single research instrument for exploration of disease mechanisms, retinal cellular architecture, and visual psychophysics.

  20. System Level Applications of Adaptive Computing (SLAAC)

    DTIC Science & Technology

    2003-11-01

    AFRL-IF-RS-TR-2003-255 Final Technical Report November 2003 SYSTEM LEVEL APPLICATIONS OF ADAPTIVE COMPUTING (SLAAC...NOVEMBER 2003 3. REPORT TYPE AND DATES COVERED Final Jul 97 – May 03 4. TITLE AND SUBTITLE SYSTEM LEVEL APPLICATIONS OF ADAPTIVE COMPUTING (SLAAC...importance are described further in Sandia’s final report . 6.2 Technical Approach The CDI algorithm requires significantly more computation power and

  1. Adaptive optics for ultra short pulsed lasers in UHV environment

    NASA Astrophysics Data System (ADS)

    Deneuville, Francois; Ropert, Laurent; Sauvageot, Paul; Theis, Sébastien

    2015-02-01

    ISP SYSTEM has developed an electro-mechanical deformable mirror compatible with Ultra High Vacuum environment, suitable for ultra short pulsed lasers. The design of the MD-AME deformable mirror is based on force application on numerous locations. μ-AME actuators are driven by stepper motors, and their patented special design allows controlling the force with a very high accuracy. Materials and assembly method have been adapted to UHV constraints and the performances were evaluated on a first application for a beam with a diameter of 250mm. A Strehl ratio above 0.9 was reached for this application. Optical aberrations up to Zernike order 5 can be corrected with a very low residual error as for standard MD-AME mirror. Amplitude can reach up to several hundreds of μm for low order corrections. Hysteresis is lower than 0.1% and linearity better than 99%. Contrary to piezo-electric actuators, the μ-AME actuators avoid print-through effects and they permit to keep the mirror shape stable even unpowered, providing a high resistance to electro-magnetic pulses. The deformable mirror design allows changing easily an actuator or even the membrane if needed, in order to improve the facility availability. They are designed for circular, square or elliptical aperture from 30mm up to 500mm or more, with incidence angle from 0° to 45°. They can be equipped with passive or active cooling for high power lasers with high repetition rate.

  2. SPECKLE NOISE SUBTRACTION AND SUPPRESSION WITH ADAPTIVE OPTICS CORONAGRAPHIC IMAGING

    SciTech Connect

    Ren Deqing; Dou Jiangpei; Zhang Xi; Zhu Yongtian

    2012-07-10

    Future ground-based direct imaging of exoplanets depends critically on high-contrast coronagraph and wave-front manipulation. A coronagraph is designed to remove most of the unaberrated starlight. Because of the wave-front error, which is inherit from the atmospheric turbulence from ground observations, a coronagraph cannot deliver its theoretical performance, and speckle noise will limit the high-contrast imaging performance. Recently, extreme adaptive optics, which can deliver an extremely high Strehl ratio, is being developed for such a challenging mission. In this publication, we show that barely taking a long-exposure image does not provide much gain for coronagraphic imaging with adaptive optics. We further discuss a speckle subtraction and suppression technique that fully takes advantage of the high contrast provided by the coronagraph, as well as the wave front corrected by the adaptive optics. This technique works well for coronagraphic imaging with conventional adaptive optics with a moderate Strehl ratio, as well as for extreme adaptive optics with a high Strehl ratio. We show how to substrate and suppress speckle noise efficiently up to the third order, which is critical for future ground-based high-contrast imaging. Numerical simulations are conducted to fully demonstrate this technique.

  3. An adaptive optics biomicroscope for mouse retinal imaging

    NASA Astrophysics Data System (ADS)

    Biss, David P.; Webb, Robert H.; Zhou, Yaopeng; Bifano, Thomas G.; Zamiri, Parisa; Lin, Charles P.

    2007-02-01

    In studying retinal disease on a microscopic level, in vivo imaging has allowed researchers to track disease progression in a single animal over time without sacrificing large numbers of animals for statistical studies. Historically, a drawback of in vivo retinal imaging, when compared to ex vivo imaging, is decreased image resolution due to aberrations present in the mouse eye. Adaptive optics has successfully corrected phase aberrations introduced the eye in ophthalmic imaging in humans. We are using adaptive optics to correct for aberrations introduced by the mouse eye in hopes of achieving cellular resolution retinal images of mice in vivo. In addition to using a wavefront sensor to drive the adaptive optic element, we explore the using image data to correct for wavefront aberrations introduced by the mouse eye. Image data, in the form of the confocal detection pinhole intensity are used as the feedback mechanism to control the MEMS deformable mirror in the adaptive optics system. Correction for wavefront sensing and sensor-less adaptive optics systems are presented.

  4. The Adaptive Optics Facility: Commissioning Progress and Results

    NASA Astrophysics Data System (ADS)

    Arsenault, R.; Madec, P.-Y.; Vernet, E.; Hackenberg, W.; La Penna, P.; Paufique, J.; Kuntschner, H.; Pirard, J.-F.; Kolb, J.; Hubin, N.

    2017-06-01

    All the Adaptive Optics Facility (AOF) subsystems are now in Paranal and the project team is working on commissioning activities on Unit Telescope 4 (UT4) of the Very Large Telescope. Excellent progress has been made; the new secondary mirror unit, the Deformable Secondary Mirror (DSM), was installed in October 2016 and UT4 is now operating routinely with the DSM in non-adaptive optics mode. The other modules of the AOF, the Ground Atmospheric Layer Adaptive optiCs for Spectroscopic Imaging (GALACSI), the 4 Laser Guide Star Facility (4LGSF) and the GRound-layer Adaptive optics Assisted by Lasers (GRAAL), have been installed and are being qualified. The coupling with the High Acuity Wide field K-band Imager (HAWK-I) and the Multi Unit Spectroscopic Explorer (MUSE) has been tested and all elements are functional and ready to proceed with their full commissioning. The goal for the AOF is to complete GALACSI wide-field mode technical commissioning by the end of summer 2017 and the GRAAL ground-layer adaptive optics mode by the end of the year.

  5. Adaptive Optics Retinal Imaging – Clinical Opportunities and Challenges

    PubMed Central

    Carroll, Joseph; Kay, David B.; Scoles, Drew; Dubra, Alfredo; Lombardo, Marco

    2014-01-01

    The array of therapeutic options available to clinicians for treating retinal disease is expanding. With these advances comes the need for better understanding of the etiology of these diseases on a cellular level as well as improved non-invasive tools for identifying the best candidates for given therapies and monitoring the efficacy of those therapies. While spectral domain optical coherence tomography (SD-OCT) offers a widely available tool for clinicians to assay the living retina, it suffers from poor lateral resolution due to the eye’s monochromatic aberrations. Adaptive optics (AO) is a technique to compensate for the eye’s aberrations and provide nearly diffraction-limited resolution. The result is the ability to visualize the living retina with cellular resolution. While AO is unquestionably a powerful research tool, many clinicians remain undecided on the clinical potential of AO imaging – putting many at a crossroads with respect to adoption of this technology. This review will briefly summarize the current state of AO retinal imaging, discuss current as well as future clinical applications of AO retinal imaging, and finally provide some discussion of research needs to facilitate more widespread clinical use. PMID:23621343

  6. Architectures for parallel DSP-based adaptive optics feedback control

    NASA Astrophysics Data System (ADS)

    McCarthy, Daniel F.

    1999-11-01

    We have developed a digital image processing system for real-time digital image processing feedback control of adaptive optics systems and simulation of optical image processing algorithms. The system uses multi-computer architecture to capture data from an imaging device such as a charge coupled device camera, process the image data, and control a spatial light-modulator, typically a liquid crystal modulator or a micro-electro mechanical system. The system is a Windows NT Pentium-based system combined with a commercial off-the-shelf peripheral component interconnect bus multi-processor system. The multi-processor is based on the Analog Devices super Harvard architecture computer (SHARC) processor, and field programmable gate arrays (FPGAs). The SHARCs provide a scalable reconfigurable C language-based digital signal processing (DSP) development environment. The FPGAs are typically used as reprogrammable interface controllers designed to integrate several off-the- shelf and custom imagers and light modulators into the system. The FPGAs can also be used in concert with the SHARCs for implementation of application-specific high-speed DSP algorithms.

  7. NAOMI: adaptive optics at the WHT

    NASA Astrophysics Data System (ADS)

    Benn, Chris R.; Blanken, Maarten; Bevil, Craige; Els, Sebastian; Goodsell, Stephen; Gregory, Tom; Jolley, Paul; Longmore, Andy J.; Martin, Olivier; Myers, Richard M.; Ostensen, Roy; Rees, Simon; Rutten, Rene G. M.; Soechting, Ilona; Talbot, Gordon; Tulloch, Simon M.

    2004-10-01

    NAOMI is the AO system of the 4.2-m William Herschel Telescope on La Palma. It delivers near-diffraction-limited images in the IR, and a significantly improved PSF at optical wavelengths. The science cameras currently comprise an IR imager (INGRID), an optical integral-field spectrograph (OASIS) and a coronagraph which may be placed in the light path to either instrument. 19 science programmes were observed during 2002-3. Observing overheads are small, with as much as 60% of the night spent integrating on science targets. In late 2004 this year, the WFS will be equipped with a low-noise L3 CCD, giving a gain of a factor of 2 in S:N for faint guide stars. A Rayleigh laser guide star is under development, with first light expected summer 2006, providing a unique facility: AO-corrected optical integral-field spectroscopy anywhere on the northern sky.

  8. Fine Surface Control of Flexible Space Mirrors Using Adaptive Optics and Robust Control

    DTIC Science & Technology

    2009-03-01

    Structure/Control Integrated Experiment ( ASCIE ) testbed, a segmented optical system also used by [10]. In physical appearance, the ASCIE is quite similar...structure. Unlike the model used for this dissertation, however, the ASCIE is not an adaptive optics system. It 14 contains only 24 sensor inputs...for much of the application in this dissertation. Specifically, the work on the ASCIE demonstrated that stochastic controller design methods were

  9. Very Large Telescope Adaptive Optics Community Days Report on the ESO Workshop

    NASA Astrophysics Data System (ADS)

    Leibundgut, B.; Kasper, M.; Kuntschner, H.

    2016-12-01

    The future of adaptive optics (AO) instruments at the VLT was discussed during a two-day workshop. Three major directions emerged from these discussions: adaptive optics in the optical; multi-object adaptive optics (MOAO); and extreme adaptive optics (XAO). The science cases for these three options were presented and the discussions are summarised. ESO is now planning to provide detailed science cases for an optical AO system and to prepare upgrade plans for XAO and MOAO.

  10. Optical Amplifier for Space Applications

    NASA Technical Reports Server (NTRS)

    Fork, Richard L.; Cole, Spencer T.; Gamble, Lisa J.; Diffey, William M.; Keys, Andrew S.

    1999-01-01

    We describe an optical amplifier designed to amplify a spatially sampled component of an optical wavefront to kilowatt average power. The goal is means for implementing a strategy of spatially segmenting a large aperture wavefront, amplifying the individual segments, maintaining the phase coherence of the segments by active means, and imaging the resultant amplified coherent field. Applications of interest are the transmission of space solar power over multi-megameter distances, as to distant spacecraft, or to remote sites with no preexisting power grid.

  11. Scientific results using the Mount Wilson Institute adaptive optics system

    NASA Astrophysics Data System (ADS)

    ten Brummelaar, Theo A.; Hartkopf, W. I.; McAlister, Harold A.; Mason, Brian D.; Roberts, L. C.; Turner, Nils H.

    1998-09-01

    During 1996 and 1997 more than 20 nights observing time have been used by, or allocated to, the CHARPA group at Georgia State University using the Mount Wilson Institute Adaptive Optics mounted on the Hooker 100 inch telescope on Mt. Wilson. Several scientific programs are being pursued including: differential photometry of binary stars; a search for faint companions of local solar type stars; attempts to image dust shells around YSOs; and experiments involving the combination of non-redundant aperture masking interferometry and adaptive optics. We have learned, and continue to learn, a great deal about the problems associated with, and methods of calibration of, adaptive optics images, especially in the area of accurate photometric measurements. So far, more than 30 binary systems have been measured in multiple filters and several previously unknown faint companions to local stars have been identified.

  12. Wavelet methods in multi-conjugate adaptive optics

    NASA Astrophysics Data System (ADS)

    Helin, T.; Yudytskiy, M.

    2013-08-01

    The next generation ground-based telescopes rely heavily on adaptive optics for overcoming the limitation of atmospheric turbulence. In the future adaptive optics modalities, like multi-conjugate adaptive optics (MCAO), atmospheric tomography is the major mathematical and computational challenge. In this severely ill-posed problem, a fast and stable reconstruction algorithm is needed that can take into account many real-life phenomena of telescope imaging. We introduce a novel reconstruction method for the atmospheric tomography problem and demonstrate its performance and flexibility in the context of MCAO. Our method is based on using locality properties of compactly supported wavelets, both in the spatial and frequency domains. The reconstruction in the atmospheric tomography problem is obtained by solving the Bayesian MAP estimator with a conjugate-gradient-based algorithm. An accelerated algorithm with preconditioning is also introduced. Numerical performance is demonstrated on the official end-to-end simulation tool OCTOPUS of European Southern Observatory.

  13. The Surface of Titan from Adaptive Optics Observations

    NASA Astrophysics Data System (ADS)

    Gibbard, S. G.; Macintosh, B.; Max, C.; Roe, H.; de Pater, I.; Young, E. F.; McKay, C. P.

    Saturn's largest moon Titan is the only satellite in the solar system with a substantial atmosphere. Photolysis of methane creates a hydrocarbon haze in Titan's atmosphere that is opaque to visible light. The new adaptive optics system on the 10-meter W.M. Keck Telescope enables us to observe Titan with a resolution of 0.04 arcseconds, or 20 resolution elements across the disk. By observing at near-infrared wavelengths that are methane band windows we can see through Titan's hydrocarbon haze to the surface beneath. Recent adaptive optics images of Titan both in broadband (J, H, and K) filters and in narrowband filters that selectively probe Titan's surface and atmosphere allow us to determine surface albedo and properties of the hydrocarbon haze layer. Future observations will include high-resolution spectroscopy coupled with adaptive optics to obtain spectra of individual surface features.

  14. Beaconless adaptive-optics technique for HEL beam control

    NASA Astrophysics Data System (ADS)

    Khizhnyak, Anatoliy; Markov, Vladimir

    2016-05-01

    Effective performance of forthcoming laser systems capable of power delivery on a distant target requires an adaptive optics system to correct atmospheric perturbations on the laser beam. The turbulence-induced effects are responsible for beam wobbling, wandering, and intensity scintillation, resulting in degradation of the beam quality and power density on the target. Adaptive optics methods are used to compensate for these negative effects. In its turn, operation of the AOS system requires a reference wave that can be generated by the beacon on the target. This report discusses a beaconless approach for wavefront correction with its performance based on the detection of the target-scattered light. Postprocessing of the beacon-generated light field enables retrieval and detailed characterization of the turbulence-perturbed wavefront -data that is essential to control the adaptive optics module of a high-power laser system.

  15. TOPICAL REVIEW: Inverse problems in astronomical adaptive optics

    NASA Astrophysics Data System (ADS)

    Ellerbroek, B. L.; Vogel, C. R.

    2009-06-01

    Adaptive optics (AO) is a technology used in ground-based astronomy to correct for the wavefront aberrations and loss of image quality caused by atmospheric turbulence. Provided some difficult technical problems can be overcome, AO will enable future astronomers to achieve nearly diffraction-limited performance with the extremely large telescopes that are currently under development, thereby greatly improving spatial resolution, spectral resolution and observing efficiency which will be achieved. The goal of this topical review is to present to the inverse problems community a representative sample of these problems. In this review, we first present a tutorial overview of the mathematical models and techniques used in current AO systems. We then examine in detail the following topics: laser guidestar adaptive optics, multi-conjugate and multi-object adaptive optics, high-contrast imaging and deformable mirror modeling and parameter identification.

  16. Applications of multilayer optics

    NASA Astrophysics Data System (ADS)

    Wang, Zhanshan; Zhu, Jingtao; Mu, Baozhong; Zhang, Zhong; Wang, Fengli; Xu, Jing; Li, Wenbin; Chen, Lingyan

    2010-11-01

    Recent development of multilayer mirror and its applications in extreme ultraviolet (EUV), soft X-ray ranges in China was reviewed in this paper. Three types of multilayer mirrors were developed with special performance for dense plasma diagnostics, EUV astronomical observation. Firstly, dual-periodic W/B 4C multilayer mirror was designed for Kirkpatrick-Baez (K-B) microscopy working at TiKα line (4.75 keV), which is highly reflective both at hard X-ray (CuKα line at 8.05 keV) and soft X-ray (4.75 keV). Using this mirror, the K-B system can be aligned conveniently in air using hard X-ray instead of in vacuum. The second mirror is aperiodic Mg/SiC multilayer, also a bi-functional mirror with high reflectivity for He-II emission line (30.4 nm) but suppressing He-I emission line (58.4 nm) in astronomy observation, which will replace the traditional combination of periodic multilayer and the fragile film filter. This will be more safe in satellite launching. The third mirror is Mo/Si periodic multilayer, depositing on a parabolic substrate with diameter of 230 mm, which is designed for EUV telescope for imaging of solar corona by selecting Fe-XII emission (19.5 nm). The uniformity of lateral layer thickness distribution is within ±0.3% along the diameter of mirror, measured by X-ray reflectometry. The measured peak reflectivity is 42% at the wavelength of 19.5 nm. All these multilayer mirrors were prepared by using magnetron sputtering system in our group.

  17. Accuracy requirements of optical linear algebra processors in adaptive optics imaging systems.

    PubMed

    Downie, J D; Goodman, J W

    1989-10-15

    A ground-based adaptive optics imaging telescope system attempts to improve image quality by measuring and correcting for atmospherically induced wavefront aberrations. The necessary control computations during each cycle will take a finite amount of time, which adds to the residual error variance since the atmosphere continues to change during that time. Thus an optical processor may be well-suited for this task. This paper investigates this possibility by studying the accuracy requirements in a general optical processor that will make it competitive with, or superior to, a conventional digital computer for adaptive optics use.

  18. Adaptive optics for the laser fabrication of 3D graphitic microwires in diamond

    NASA Astrophysics Data System (ADS)

    Salter, P. S.; Sun, B.; Booth, M. J.

    2015-03-01

    Graphitic wires embedded beneath the surface of single crystal diamond are demonstrated. Through a combination of ultrashort (femtosecond) pulsed fabrication, high numerical aperture focusing and adaptive optics, wires are created with sub micrometre dimensions that can follow any three dimensional path within the diamond. The increased level of focal control available through the use of adaptive optics appears particularly important in the generation of high quality wires, with measured conductivities over an order of magnitude greater than previous laser-induced graphitic wires in diamond. Applications for the embedded wires are discussed.

  19. A geometric view of adaptive optics control: boiling atmosphere model

    NASA Astrophysics Data System (ADS)

    Wiberg, Donald M.; Max, Claire E.; Gavel, Donald T.

    2004-10-01

    The separation principle of optimal adaptive optics control is derived, and definitions of controllability and observability are introduced. An exact finite dimensional state space representation of the control system dynamics is obtained without the need for truncation in modes such as Zernikes. The uncertainty of sensing uncontrollable modes confuses present adaptive optics controllers. This uncertainty can be modeled by a Kalman filter. Reducing this uncertainty permits increased gain, increasing the Strehl, which is done by an optimal control law derived here. A general model of the atmosphere is considered, including boiling.

  20. Retinal imaging with adaptive optics full-field OCT

    NASA Astrophysics Data System (ADS)

    Xiao, Peng; Fink, Mathias; Boccara, A. Claude

    2017-02-01

    Adaptive optics full-filed OCT (FFOCT) with a transmissive liquid crystal spatial light modulator (LCSLM) as wavefront corrector is used without strict plane conjugation for low order aberrations corrections. We validated experimentally that FFOCT resolution is independent of aberrations and only reduce the signal level. A signal based sensorless algorithm was thus applied for wavefront distortion compensation. Image quality improvements by the wavefront sensorless control of the LCSLM were evaluated on in vitro samples. By replacing the FFOCT sample arm objective with an artificial eye used to train ophthalmologists, adaptive optics retinal imaging was achieved. In vivo experiments using a liquid lens to correct focus and astigmatism are underway.

  1. Surface plasmon wave adapter designed with transformation optics.

    PubMed

    Zhang, Jingjing; Xiao, Sanshui; Wubs, Martijn; Mortensen, Niels Asger

    2011-06-28

    On the basis of transformation optics, we propose the design of a surface plasmon wave adapter which confines surface plasmon waves on non-uniform metal surfaces and enables adiabatic mode transformation of surface plasmon polaritons with very short tapers. This adapter can be simply achieved with homogeneous anisotropic naturally occurring materials or subwavelength grating-structured dielectric materials. Full wave simulations based on a finite-element method have been performed to validate our proposal.

  2. Adaptive interferometry for high sensitivity optical fiber sensing

    NASA Astrophysics Data System (ADS)

    Peigné, A.; Bortolozzo, U.; Residori, S.; Molin, S.; Dolfi, D.; Huignard, J.-P.

    2015-09-01

    We report on the use of an adaptive holographic interferometer, based on a liquid crystal light valve, to achieve phase shift measurements in an optical fiber. Owing to the physical mechanisms involved, the interferometer adapts itself to slow phase variations. As a consequence, it is possible to use a multimode fiber for sensing, which improves the sensitivity. Moreover, a distributed architecture relying on phase-OTDR principle is presented and a localization experiment is performed.

  3. Holographic fluorescence microscopy with incoherent digital holographic adaptive optics.

    PubMed

    Jang, Changwon; Kim, Jonghyun; Clark, David C; Lee, Seungjae; Lee, Byoungho; Kim, Myung K

    2015-01-01

    Introduction of adaptive optics technology into astronomy and ophthalmology has made great contributions in these fields, allowing one to recover images blurred by atmospheric turbulence or aberrations of the eye. Similar adaptive optics improvement in microscopic imaging is also of interest to researchers using various techniques. Current technology of adaptive optics typically contains three key elements: a wavefront sensor, wavefront corrector, and controller. These hardware elements tend to be bulky, expensive, and limited in resolution, involving, for example, lenslet arrays for sensing or multiactuator deformable mirrors for correcting. We have previously introduced an alternate approach based on unique capabilities of digital holography, namely direct access to the phase profile of an optical field and the ability to numerically manipulate the phase profile. We have also demonstrated that direct access and compensation of the phase profile are possible not only with conventional coherent digital holography, but also with a new type of digital holography using incoherent light: selfinterference incoherent digital holography (SIDH). The SIDH generates a complex—i.e., amplitude plus phase—hologram from one or several interferograms acquired with incoherent light, such as LEDs, lamps, sunlight, or fluorescence. The complex point spread function can be measured using guide star illumination and it allows deterministic deconvolution of the full-field image. We present experimental demonstration of aberration compensation in holographic fluorescence microscopy using SIDH. Adaptive optics by SIDH provides new tools for improved cellular fluorescence microscopy through intact tissue layers or other types of aberrant media.

  4. Holographic fluorescence microscopy with incoherent digital holographic adaptive optics

    NASA Astrophysics Data System (ADS)

    Jang, Changwon; Kim, Jonghyun; Clark, David C.; Lee, Seungjae; Lee, Byoungho; Kim, Myung K.

    2015-11-01

    Introduction of adaptive optics technology into astronomy and ophthalmology has made great contributions in these fields, allowing one to recover images blurred by atmospheric turbulence or aberrations of the eye. Similar adaptive optics improvement in microscopic imaging is also of interest to researchers using various techniques. Current technology of adaptive optics typically contains three key elements: a wavefront sensor, wavefront corrector, and controller. These hardware elements tend to be bulky, expensive, and limited in resolution, involving, for example, lenslet arrays for sensing or multiactuator deformable mirrors for correcting. We have previously introduced an alternate approach based on unique capabilities of digital holography, namely direct access to the phase profile of an optical field and the ability to numerically manipulate the phase profile. We have also demonstrated that direct access and compensation of the phase profile are possible not only with conventional coherent digital holography, but also with a new type of digital holography using incoherent light: self­interference incoherent digital holography (SIDH). The SIDH generates a complex-i.e., amplitude plus phase-hologram from one or several interferograms acquired with incoherent light, such as LEDs, lamps, sunlight, or fluorescence. The complex point spread function can be measured using guide star illumination and it allows deterministic deconvolution of the full-field image. We present experimental demonstration of aberration compensation in holographic fluorescence microscopy using SIDH. Adaptive optics by SIDH provides new tools for improved cellular fluorescence microscopy through intact tissue layers or other types of aberrant media.

  5. Characterization and Operation of Liquid Crystal Adaptive Optics Phoropter

    SciTech Connect

    Awwal, A; Bauman, B; Gavel, D; Olivier, S; Jones, S; Hardy, J L; Barnes, T; Werner, J S

    2003-02-05

    Adaptive optics (AO), a mature technology developed for astronomy to compensate for the effects of atmospheric turbulence, can also be used to correct the aberrations of the eye. The classic phoropter is used by ophthalmologists and optometrists to estimate and correct the lower-order aberrations of the eye, defocus and astigmatism, in order to derive a vision correction prescription for their patients. An adaptive optics phoropter measures and corrects the aberrations in the human eye using adaptive optics techniques, which are capable of dealing with both the standard low-order aberrations and higher-order aberrations, including coma and spherical aberration. High-order aberrations have been shown to degrade visual performance for clinical subjects in initial investigations. An adaptive optics phoropter has been designed and constructed based on a Shack-Hartmann sensor to measure the aberrations of the eye, and a liquid crystal spatial light modulator to compensate for them. This system should produce near diffraction-limited optical image quality at the retina, which will enable investigation of the psychophysical limits of human vision. This paper describes the characterization and operation of the AO phoropter with results from human subject testing.

  6. Optical techniques to understand biofunctional adaptation in human dentine

    NASA Astrophysics Data System (ADS)

    Kishen, Anil; Asundi, Anand K.

    2004-08-01

    Human tooth structure in the oral environment is subjected to mechanical forces and thermal fluctuations. Dentine, the major component of the tooth structure, is a bio-composite, mainly composed of a highly mineralized phase and a collagenous phase. When subjected to changes in load and/or temperature, dentine will experience stresses and strains distribution within their structure. Though such effects are found to cause deleterious effects on artificial dental restorations, biological structures such as dentine seem to posses an inherent ability to adapt to functional thermo-mechanical loads. Optical techniques enable visualization and quantification of deformation, strain and stress on dental structures and provide a better understanding on their thermo-mechanical response. In this study 2-dimensional and 3-dimensional digital photoelasticity, digital moiré interferometry and Electronic Speckle Pattern Interferometry (ESPI) are all shown to be quite promising in this application. This paper will highlight these techniques and the corresponding applications. These experiments will aid in designing and development of better dental restorations and implants in clinical practice.

  7. Adaptive optics vision simulation and perceptual learning system based on a 35-element bimorph deformable mirror.

    PubMed

    Dai, Yun; Zhao, Lina; Xiao, Fei; Zhao, Haoxin; Bao, Hua; Zhou, Hong; Zhou, Yifeng; Zhang, Yudong

    2015-02-10

    An adaptive optics visual simulation combined with a perceptual learning (PL) system based on a 35-element bimorph deformable mirror (DM) was established. The larger stroke and smaller size of the bimorph DM made the system have larger aberration correction or superposition ability and be more compact. By simply modifying the control matrix or the reference matrix, select correction or superposition of aberrations was realized in real time similar to a conventional adaptive optics closed-loop correction. PL function was first integrated in addition to conventional adaptive optics visual simulation. PL training undertaken with high-order aberrations correction obviously improved the visual function of adult anisometropic amblyopia. The preliminary application of high-order aberrations correction with PL training on amblyopia treatment was being validated with a large scale population, which might have great potential in amblyopia treatment and visual performance maintenance.

  8. Solar multi-conjugate adaptive optics based on high order ground layer adaptive optics and low order high altitude correction.

    PubMed

    Zhang, Lanqiang; Guo, Youming; Rao, Changhui

    2017-02-20

    Multi-conjugate adaptive optics (MCAO) is the most promising technique currently developed to enlarge the corrected field of view of adaptive optics for astronomy. In this paper, we propose a new configuration of solar MCAO based on high order ground layer adaptive optics and low order high altitude correction, which result in a homogeneous correction effect in the whole field of view. An individual high order multiple direction Shack-Hartmann wavefront sensor is employed in the configuration to detect the ground layer turbulence for low altitude correction. Furthermore, the other low order multiple direction Shack-Hartmann wavefront sensor supplies the wavefront information caused by high layers' turbulence through atmospheric tomography for high altitude correction. Simulation results based on the system design at the 1-meter New Vacuum Solar Telescope show that the correction uniform of the new scheme is obviously improved compared to conventional solar MCAO configuration.

  9. Design strategies for irregularly adapting parallel applications

    SciTech Connect

    Oliker, Leonid; Biswas, Rupak; Shan, Hongzhang; Sing, Jaswinder Pal

    2000-11-01

    Achieving scalable performance for dynamic irregular applications is eminently challenging. Traditional message-passing approaches have been making steady progress towards this goal; however, they suffer from complex implementation requirements. The use of a global address space greatly simplifies the programming task, but can degrade the performance of dynamically adapting computations. In this work, we examine two major classes of adaptive applications, under five competing programming methodologies and four leading parallel architectures. Results indicate that it is possible to achieve message-passing performance using shared-memory programming techniques by carefully following the same high level strategies. Adaptive applications have computational work loads and communication patterns which change unpredictably at runtime, requiring dynamic load balancing to achieve scalable performance on parallel machines. Efficient parallel implementations of such adaptive applications are therefore a challenging task. This work examines the implementation of two typical adaptive applications, Dynamic Remeshing and N-Body, across various programming paradigms and architectural platforms. We compare several critical factors of the parallel code development, including performance, programmability, scalability, algorithmic development, and portability.

  10. Low-cost high performance adaptive optics real-time controller in free space optical communication system

    NASA Astrophysics Data System (ADS)

    Chen, Shanqiu; Liu, Chao; Zhao, Enyi; Xian, Hao; Xu, Bing; Ye, Yutang

    2014-11-01

    This paper proposed a low-cost and high performance adaptive optics real-time controller in free space optical communication system. Real-time controller is constructed with a 4-core CPU with Linux operation system patched with Real-Time Application Interface (RTAI) and a frame-grabber, and the whole cost is below $6000. Multi-core parallel processing scheme and SSE instruction optimization for reconstruction process result in about 5 speedup, and overall processing time for this 137-element adaptive optic system can reach below 100 us and with latency about 50 us by utilizing streamlined processing scheme, which meet the requirement of processing at frequency over 1709 Hz. Real-time data storage system designed by circle buffer make this system to store consecutive image frames and provide an approach to analysis the image data and intermediate data such as slope information.

  11. Holographic fluorescence microscopy with incoherent digital holographic adaptive optics

    NASA Astrophysics Data System (ADS)

    Jang, Changwon; Kim, Jonghyun; Clark, David C.; Lee, Byoungho; Kim, Myung K.

    2015-03-01

    Introduction of adaptive optics technology into astronomy and ophthalmology has made great contributions in these fields, allowing one to recover images blurred by atmospheric turbulence or aberrations of the eye. Similar adaptive optics improvement in microscopic imaging is also of interest to researchers using various techniques. Current technology of adaptive optics typically contains three key elements: wavefront sensor, wavefront corrector and controller. These hardware elements tend to be bulky, expensive, and limited in resolution, involving, e.g., lenslet arrays for sensing or multi-acuator deformable mirrors for correcting. We have previously introduced an alternate approach to adaptive optics based on unique capabilities of digital holography, namely direct access to the phase profile of an optical field and the ability to numerically manipulate the phase profile. We have also demonstrated that direct access and compensation of the phase profile is possible not only with the conventional coherent type of digital holography, but also with a new type of digital holography using incoherent light: self-interference incoherent digital holography (SIDH). The SIDH generates complex - i.e. amplitude plus phase - hologram from one or several interferograms acquired with incoherent light, such as LEDs, lamps, sunlight, or fluorescence. The complex point spread function can be measured using a guide star illumination and it allows deterministic deconvolution of the full-field image. We present experimental demonstration of aberration compensation in holographic fluorescence microscopy using SIDH. The adaptive optics by SIDH provides new tools for improved cellular fluorescence microscopy through intact tissue layers or other types of aberrant media.

  12. Improved visualization of outer retinal morphology with aberration cancelling reflective optical design for adaptive optics - optical coherence tomography

    PubMed Central

    Lee, Sang-Hyuck; Werner, John S.; Zawadzki, Robert J.

    2013-01-01

    We present an aberration cancelling optical design for a reflective adaptive optics - optical coherence tomography (AO-OCT) retinal imaging system. The optical performance of this instrument is compared to our previous multimodal AO-OCT/AO-SLO retinal imaging system. The feasibility of new instrumentation for improved visualization of microscopic retinal structures is discussed. Examples of images acquired with this new AO-OCT instrument are presented. PMID:24298411

  13. Optical slot antenna and its application

    NASA Astrophysics Data System (ADS)

    Park, Yeonsang; Kim, Jineun; Roh, Young-Geun; Park, Q.-Han

    2017-02-01

    We present an optical slot antenna and its application. By measuring transmission spectra and far-field radiation pattern of metallic slots with nanometer scale, we show that a metallic nanoslot has the properties of an antenna, which are resonance, polarization, and bidirectional far-field radiation pattern, and can be regarded as a magnetic dipole in optical region. Additionally, we also make the unidirectional radiation by adapting the geometry of RF Yagi-Uda antenna and applying slot antenna. By the aid of phase analysis based on 3-dimensional finite-difference time-domain simulation, we can increase the front-to-back ratio of an optical slot Yagi-Uda antenna up to about 5. As the application of a slot antenna, we integrate a metal-insulator-metal plasmonic waveguide with a slot antenna. A surface plasmon waveguide mode propagating in MIM structure is well-coupled to a slot antenna and radiates into free-space in form of dipole radiation. By adding an auxiliary structure that has the role of reflector as like a slot Yagi-Uda antenna, the direction of radiation from a slot antenna integrated with a plasmonic waveguide can be controlled efficiently. Besides the possibility of integration with a waveguide, we expect that a slot antenna can be applied to active devices such as light emitting diodes or lasers for the future.

  14. Nonlinear optics in optical-fiber nanowires and their applications

    NASA Astrophysics Data System (ADS)

    Xu, Fei; Wu, Zhen-xing; Lu, Yan-qing

    2017-09-01

    We review recent research on nonlinear optical interactions in optical-fiber nanowires (OFNs) with sub-micron transverse dimensions. Such OFNs, which are fabricated from standard optical fibers, offer numerous beneficial optical and mechanical properties, including strong evanescent fields, high flexibility and configurability, a small mass, and low-loss interconnection to other optical fibers and fiberized components. In particular, the strong confinement of light enables a large enhancement of nonlinear interactions and group-velocity dispersion engineering. The combination of these properties makes OFNs ideal for many nonlinear optical applications, including harmonic generation, Brillouin scattering, four-wave mixing, supercontinuum generation, and optomechanics. With the incorporation of new materials, OFNs should be ideally suited for a host of nonlinear optical interactions and devices and offer great potential in miniature fiber devices for optical telecommunications and optical sensor applications.

  15. Adaptive subwavelength control of nano-optical fields.

    PubMed

    Aeschlimann, Martin; Bauer, Michael; Bayer, Daniela; Brixner, Tobias; García de Abajo, F Javier; Pfeiffer, Walter; Rohmer, Martin; Spindler, Christian; Steeb, Felix

    2007-03-15

    Adaptive shaping of the phase and amplitude of femtosecond laser pulses has been developed into an efficient tool for the directed manipulation of interference phenomena, thus providing coherent control over various quantum-mechanical systems. Temporal resolution in the femtosecond or even attosecond range has been demonstrated, but spatial resolution is limited by diffraction to approximately half the wavelength of the light field (that is, several hundred nanometres). Theory has indicated that the spatial limitation to coherent control can be overcome with the illumination of nanostructures: the spatial near-field distribution was shown to depend on the linear chirp of an irradiating laser pulse. An extension of this idea to adaptive control, combining multiparameter pulse shaping with a learning algorithm, demonstrated the generation of user-specified optical near-field distributions in an optimal and flexible fashion. Shaping of the polarization of the laser pulse provides a particularly efficient and versatile nano-optical manipulation method. Here we demonstrate the feasibility of this concept experimentally, by tailoring the optical near field in the vicinity of silver nanostructures through adaptive polarization shaping of femtosecond laser pulses and then probing the lateral field distribution by two-photon photoemission electron microscopy. In this combination of adaptive control and nano-optics, we achieve subwavelength dynamic localization of electromagnetic intensity on the nanometre scale and thus overcome the spatial restrictions of conventional optics. This experimental realization of theoretical suggestions opens a number of perspectives in coherent control, nano-optics, nonlinear spectroscopy, and other research fields in which optical investigations are carried out with spatial or temporal resolution.

  16. Design, fabrication and characterization of MEMS deformable mirrors for ocular adaptive optics

    NASA Astrophysics Data System (ADS)

    Park, Hyunkyu

    This dissertation describes the design and modeling of MEMS-based bimorph deformable mirrors for adaptive optics as well as the characterization of fabricated devices. The objective of this research is to create a compact and low-cost deformable mirror that can be used as a phase corrector particularly for vision science applications. A fundamental theory of adaptive optics is reviewed, paying attention to the phase corrector which is a key component of the adaptive optics system. Several types of phase corrector are presented and the minimization of their size and cost using micro electromechanical systems (MEMS) technology is also discussed. Since this research is targeted towards the ophthalmic applications of adaptive optics, aberrations of the human eye are illustrated and the benefits of corrections by adaptive optics are explained. A couple of actuator types of the phase corrector that can be used in vision science are introduced and discussed their suitability for the purpose. The requirements to be an ideal deformable mirror for ocular adaptive optics are presented. The characteristics of bimorph deformable mirrors originally developed for laser communications are investigated in an effort to understand their suitability for ophthalmological adaptive optics applications. A Phase shifting interferometer setup is developed for optical characterization and fundamental theory of interferogram analysis is described along with wavefront reconstruction. The theoretical analysis of the bimorph deformable mirror begins with developing an analytical model of the laminated structure. The finite element models are also developed using COMSOL Multiphysics. Using the FEM results, the performance of deformable mirrors under various structure dimensions and operating conditions is analyzed for optimization. A basic theory of piezoelectricity is explained, followed by introduction of applications to MEMS devices. The material properties of single crystal PMN-PT adopted in

  17. Wavefront sensorless adaptive optics OCT with the DONE algorithm for in vivo human retinal imaging [Invited].

    PubMed

    Verstraete, Hans R G W; Heisler, Morgan; Ju, Myeong Jin; Wahl, Daniel; Bliek, Laurens; Kalkman, Jeroen; Bonora, Stefano; Jian, Yifan; Verhaegen, Michel; Sarunic, Marinko V

    2017-04-01

    In this report, which is an international collaboration of OCT, adaptive optics, and control research, we demonstrate the Data-based Online Nonlinear Extremum-seeker (DONE) algorithm to guide the image based optimization for wavefront sensorless adaptive optics (WFSL-AO) OCT for in vivo human retinal imaging. The ocular aberrations were corrected using a multi-actuator adaptive lens after linearization of the hysteresis in the piezoelectric actuators. The DONE algorithm succeeded in drastically improving image quality and the OCT signal intensity, up to a factor seven, while achieving a computational time of 1 ms per iteration, making it applicable for many high speed applications. We demonstrate the correction of five aberrations using 70 iterations of the DONE algorithm performed over 2.8 s of continuous volumetric OCT acquisition. Data acquired from an imaging phantom and in vivo from human research volunteers are presented.

  18. Adaptive optics for direct laser writing with plasma emission aberration sensing.

    PubMed

    Jesacher, Alexander; Marshall, Graham D; Wilson, Tony; Booth, Martin J

    2010-01-18

    Aberrations affect the focal spot quality in direct laser write applications when focusing through a refractive index mismatch. Closed loop adaptive optics can correct these aberrations if a suitable feedback signal can be found. Focusing an ultrafast laser beam into transparent dielectric material can lead to plasma formation in the focal region. We report using the supercontinuum emitted by such a plasma to measure the optical aberrations, the subsequent aberration correction using a spatial light modulator and the fabrication of nanostructures using the corrected optical system.

  19. Laser guide stars and adaptive optics for astronomy

    SciTech Connect

    Max, C.E.

    1992-07-15

    Five papers are included: feasibility experiment for sodium-alyer laser guide stars at LLNL; system design for a high power sodium beacon laser; sodium guide star adaptive optics system for astronomical imaging in the visible and near-infrared; high frame-rate, large field wavefront sensor; and resolution limits for ground-based astronomical imaging. Figs, tabs, refs.

  20. NAOMI -- Common-User Adaptive Optics at the WHT

    NASA Astrophysics Data System (ADS)

    Benn, C. R.; Ostensen, R.; Els, S.; Prada, F.; Gregory, T.; Myers, R.

    2002-10-01

    NAOMI, the WHT's adaptive-optics system, is now being used routinely with INGRID, the IR camera, to obtain near-diffraction-limited images at wavelengths 1-2.2 micron (J, H, K, and narrow-band filters). Time allocations are queue-scheduled to take advantage of the best seeing, but visiting observers are also welcome.

  1. NAOMI — A New Adaptive Optics Module for Interferometry

    NASA Astrophysics Data System (ADS)

    Dorn, R. J.; Aller-Carpentier, E.; Andolfato, L.; Berger, J.-P.; Delplancke-Ströbele, F.; Dupuy, C.; Fedrigo, E.; Gitton, P.; Hubin, N.; Le Louarn, M.; Lilley, P.; Jolley, P.; Marchetti, E.; Mclay, S.; Paufique, J.; Pasquini, L.; Quentin, J.; Rakich, A.; Ridings, R.; Reyes, J.; Schmid, C.; Suarez, M.; Phan, D. T.; Woillez, J.

    2014-06-01

    The future adaptive optics system for the Auxiliary Telescopes of the Very Large Telescope Interferometer (VLTI), NAOMI, is presented. The NAOMI project will equip the telescopes with a low-order Shack-Hartmann system for the VLTI dual-feed light beams. The key benefits to current and future VLTI instruments and the preliminary design concept are described.

  2. Auto-aligning stimulated emission depletion microscope using adaptive optics.

    PubMed

    Gould, Travis J; Kromann, Emil B; Burke, Daniel; Booth, Martin J; Bewersdorf, Joerg

    2013-06-01

    Stimulated emission depletion (STED) microscopy provides diffraction-unlimited resolution in fluorescence microscopy. Imaging at the nanoscale, however, requires precise alignment of the depletion and excitation laser foci of the STED microscope. We demonstrate here that adaptive optics can be implemented to automatically align STED and confocal images with a precision of 4.3 ± 2.3 nm.

  3. eXtreme Adaptive Optics Planet Imager: overview and status

    NASA Astrophysics Data System (ADS)

    Macintosh, Bruce A.; Bauman, Brian; Wilhelmsen Evans, Julia; Graham, James R.; Lockwood, Christopher; Poyneer, Lisa; Dillon, Daren; Gavel, Don T.; Green, Joseph J.; Lloyd, James P.; Makidon, Russell B.; Olivier, Scot; Palmer, Dave; Perrin, Marshall D.; Severson, Scott; Sheinis, Andrew I.; Sivaramakrishnan, Anand; Sommargren, Gary; Soummer, Remi; Troy, Mitchell; Wallace, J. Kent; Wishnow, Edward

    2004-10-01

    As adaptive optics (AO) matures, it becomes possible to envision AO systems oriented towards specific important scientific goals rather than general-purpose systems. One such goal for the next decade is the direct imaging detection of extrasolar planets. An "extreme" adaptive optics (ExAO) system optimized for extrasolar planet detection will have very high actuator counts and rapid update rates - designed for observations of bright stars - and will require exquisite internal calibration at the nanometer level. In addition to extrasolar planet detection, such a system will be capable of characterizing dust disks around young or mature stars, outflows from evolved stars, and high Strehl ratio imaging even at visible wavelengths. The NSF Center for Adaptive Optics has carried out a detailed conceptual design study for such an instrument, dubbed the eXtreme Adaptive Optics Planet Imager or XAOPI. XAOPI is a 4096-actuator AO system, notionally for the Keck telescope, capable of achieving contrast ratios >107 at angular separations of 0.2-1". ExAO system performance analysis is quite different than conventional AO systems - the spatial and temporal frequency content of wavefront error sources is as critical as their magnitude. We present here an overview of the XAOPI project, and an error budget highlighting the key areas determining achievable contrast. The most challenging requirement is for residual static errors to be less than 2 nm over the controlled range of spatial frequencies. If this can be achieved, direct imaging of extrasolar planets will be feasible within this decade.

  4. eXtreme Adaptive Optics Planet Imager: Overview and status

    SciTech Connect

    Macintosh, B A; Bauman, B; Evans, J W; Graham, J; Lockwood, C; Poyneer, L; Dillon, D; Gavel, D; Green, J; Lloyd, J; Makidon, R; Olivier, S; Palmer, D; Perrin, M; Severson, S; Sheinis, A; Sivaramakrishnan, A; Sommargren, G; Soumer, R; Troy, M; Wallace, K; Wishnow, E

    2004-08-18

    As adaptive optics (AO) matures, it becomes possible to envision AO systems oriented towards specific important scientific goals rather than general-purpose systems. One such goal for the next decade is the direct imaging detection of extrasolar planets. An 'extreme' adaptive optics (ExAO) system optimized for extrasolar planet detection will have very high actuator counts and rapid update rates - designed for observations of bright stars - and will require exquisite internal calibration at the nanometer level. In addition to extrasolar planet detection, such a system will be capable of characterizing dust disks around young or mature stars, outflows from evolved stars, and high Strehl ratio imaging even at visible wavelengths. The NSF Center for Adaptive Optics has carried out a detailed conceptual design study for such an instrument, dubbed the eXtreme Adaptive Optics Planet Imager or XAOPI. XAOPI is a 4096-actuator AO system, notionally for the Keck telescope, capable of achieving contrast ratios >10{sup 7} at angular separations of 0.2-1'. ExAO system performance analysis is quite different than conventional AO systems - the spatial and temporal frequency content of wavefront error sources is as critical as their magnitude. We present here an overview of the XAOPI project, and an error budget highlighting the key areas determining achievable contrast. The most challenging requirement is for residual static errors to be less than 2 nm over the controlled range of spatial frequencies. If this can be achieved, direct imaging of extrasolar planets will be feasible within this decade.

  5. Alternative Optical Architectures for Multichannel Adaptive Optical Processing

    DTIC Science & Technology

    1993-04-01

    performance of the system can also be improved if we note that the input of EdO ) need not be centered at 9a but could be cenitred at -AO+A4La so that...characterization of a multichannel adaptive system that can perform cancellation of multiple wideband (In r!ll) interference sources in the presence...development of a single-loop electronic canceller for improved phase stability after the AO tapped delay line system . 14. SUBJECT TERMS ,I PANUI OF PACES

  6. Optical fiber instrumentation and applications

    NASA Astrophysics Data System (ADS)

    Claus, Richard O.

    1997-11-01

    Optical fiber-based sensor instrumentation has been used extensively for the measurement of physical observables including strain, temperature and chemical changes in smart materials and smart structures, and have been integrated with MEMS devices to provide multi-measurement capability along the length of a fiber link or network. This plenary paper briefly outlines recent developments in such optical fiber sensor instrumentation. Fiber optic sensors are small in size, immune to electromagnetic interference and can be easily integrated with existing optical fiber hardware and components that have been developed primarily for use in the larger telecommunications market. Such sensors can be easily multiplexed, resulting in networks that can be used for the health monitoring of large structures, or the real-time monitoring of structural parameters required for structural analysis and control. This paper briefly describes and compares three current fiber sensor configurations that use Fabry-Perot interferometry and fiber Bragg gratings (FBG) and long-period grating (LPG) elements to monitor strain, temperature and other parameters. Extensive details concerning additional related work and field test results and applications are discussed in the references.

  7. Optical fiber instrumentation and applications

    NASA Astrophysics Data System (ADS)

    Claus, Richard O.

    1997-11-01

    Optical fiber-based sensor instrumentation has been used extensively for the measurement of physical observables including strain, temperature and chemical changes in smart materials and smart structures, and have been integrated with MEMS devices to provide multi-measurement capability along the length of a fiber link or network. This plenary paper briefly outlines recent developments in such optical fiber sensor instrumentation. Fiber optic sensors are small in size, immune to electromagnetic interference and can be easily integrated with existing optical fiber hardware nd components that have been developed primarily for use in the larger telecommunications market. Such sensors can be easily multiplexed, resulting in networks that can be used for the health monitoring of large structures, or the real-time monitoring of structural parameters required for structural analysis and control. This paper briefly describes and compares three current fiber sensor configurations that use Fabry-Perot interferometry and fiber Bragg gratings and long-period grating elements to monitor strain, temperature and other parameters. Extensive details concerning additional related work and field test results and applications are discussed in the references.

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

    PubMed

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

    2007-04-20

    We describe an adaptive optical system for use as a tunable focusing element. The system provides adaptive beam shaping via controlled thermal lensing in the optical elements. The system is agile, remotely controllable, touch free, and vacuum compatible; it offers a wide dynamic range, aberration-free focal length tuning, and can provide both positive and negative lensing effects. Focusing is obtained through dynamic heating of an optical element by an external pump beam. The system is especially suitable for use in interferometric gravitational wave interferometers employing high laser power, allowing for in situ control of the laser modal properties and compensation for thermal lensing of the primary laser. Using CO(2) laser heating of fused-silica substrates, we demonstrate a focal length variable from infinity to 4.0 m, with a slope of 0.082 diopter/W of absorbed heat. For on-axis operation, no higher-order modes are introduced by the adaptive optical element. Theoretical modeling of the induced optical path change and predicted thermal lens agrees well with measurement.

  9. Adaptive optics for control of the laser welding process

    NASA Astrophysics Data System (ADS)

    Mrňa, Libor; Šarbort, Martin; Řeřucha, Šimon; Jedlička, Petr

    2013-04-01

    The laser head with fixed focus optics is commonly used for the deep penetration laser welding. In such case the geometry and position of the beam waist are defined by the focusing lens. If the laser beam incident on the focusing lens is not well collimated but divergent and its divergence can be varied by proper adaptive optical elements, then also the geometry and position of the focus will be changeable. In this way it is possible to affect the energy coupling from the laser beam to the keyhole walls and thus to control the geometry and quality of the weld. In this paper we present a theoretical and numerical study of the beam shaping by adaptive optics and its influence on the weld quality. For the CO2 laser welding machine the adaptive optics was realized by a deformable mirror and itsti'ect was tested also experimentally. For the solid-state laser welding machine we designed a laser head with changeable distance between the optical fiber and the collimating lens and we simulated its performance.

  10. ADAPTIVE OPTICS: Laser refractography of optically inhomogeneous media

    NASA Astrophysics Data System (ADS)

    Raskovskaya, I. L.; Rinkevichyus, B. S.; Tolkachev, A. V.

    2007-12-01

    The basic principles of laser refractography, a new method for diagnostics of optically inhomogeneous media and flows based on refraction of spatially structured laser radiation, are described. By using 2D- and 3D-refraction patterns, the medium under investigation can be visualised and the inhomogeneity profile can be diagnosed quantitatively. The method is modified for studying edge effects and thin boundary layers in liquids and gases. Due to nearly inertialess measurements, laser refractography can be used for diagnostics of fast and transient processes. The simultaneous diagnostics of processes in various regions is provided by an extended radiation source.

  11. ARGOS - the Laser Star Adaptive Optics for LBT

    NASA Astrophysics Data System (ADS)

    Rabien, S.; Barl, L.; Beckmann, U.; Blümchen, T.; Bonaglia, M.; Borelli, J. L.; Brynnel, J.; Busoni, L.; Carbonaro, L.; Conot, C.; Davies, R.; Deysenroth, M.; Durney, O.; Elberich, M.; Esposito, S.; Gasho, V.; Gässler, W.; Gemperlein, H.; Genzel, R.; Green, R.; Haug, M.; Lloyd Hart, M.; Hubbard, P.; Kanneganti, S.; Kulas, M.; Noenickx, J.; Peter, D.; Quirrenbach, A.; Rademacher, M.; Rix, H. W.; Salinari, P.; Schwab, C.; Storm, J.; Strüder, L.; Thiel, M.; Weigelt, G.; Ziegleder, J.; de Xivry, G. Orban

    2011-09-01

    We will present the design and status of ARGOS - the Laser Guide Star adaptive optics facility for the Large Binocular Telescope. By projecting a constellation of multiple laser guide stars above each of the 8.4m primary mirrors of the LBT, ARGOS in its ground layer mode will enable a wide field adaptive optics correction for multi object spectroscopy. ARGOS implements high power pulsed green lasers and makes use of Rayleigh scattering for the guide star creation. The geometric relations of this setup in guide star height vs. primary diameter are quite comparable to an ELT with sodium guide stars. The use of LBT's adaptive secondary mirror, gated wavefront sensors, a prime focus calibration system and the laser constellation shows several aspects that may be used as pathfinding technology for the planned ELTs. In already planned upgrade steps with a hybrid Sodium-Rayleigh combination ARGOS will enable MCAO and MOAO implementations at LBT allowing unique astronomical observations.

  12. Adaptive optics at Lick Observatory: system architecture and operations

    NASA Astrophysics Data System (ADS)

    Brase, James M.; An, Jong; Avicola, Kenneth; Bissinger, Horst D.; Friedman, Herbert W.; Gavel, Donald T.; Johnston, Brooks; Max, Claire E.; Olivier, Scot S.; Presta, Robert W.; Rapp, David A.; Salmon, J. Thaddeus; Waltjen, Kenneth E.; Fisher, William A.

    1994-05-01

    We will describe an adaptive optics system developed for the 1 meter Nickel and 3 meter Shane telescopes at Lick Observatory. Observing wavelengths will be in the visible for the 1 meter telescope and in the near IR on the 3 meter. The adaptive optics system design is based on a 69 actuator continuous surface deformable mirror and a Hartmann wavefront sensor equipped with an intensified CCD framing camera. The system has been tested at the Cassegrain focus of the 1 meter telescope where the subaperture size is 12.5 cm. The wavefront control calculations are performed on a four processor single board computer controlled by a Unix-based system. We will describe the optical system and give details of the wavefront control system design. We will present predictions of the system performance and initial test results.

  13. Melanoma associated retinopathy: A new dimension using adaptive optics.

    PubMed

    Dabir, Supriya; Mangalesh, Shwetha; Govindraj, Indu; Mallipatna, Ashwin; Battu, Rajani; Shetty, Rohit

    2015-01-01

    We report a 56-year-old male patient, complaining of metamorphopsia in his left eye nevertheless visual acuity, slit lamp, and fundus examinations were within normal limits. Microperimetry (MAIA, Centervue, Italy) revealed central field loss and spectral domain optical coherence tomography (Spectralis, Heidelberg, Germany) showed disrupted cone outer segment tip layer. The patient had a diagnosis of cutaneous melanoma in his foot for which an excision biopsy with lymph node dissection was performed 5 months earlier. Our clinical diagnosis was melanoma-associated retinopathy. Electrophysiology confirmed the diagnosis. Adaptive optics retinal imaging (Imagine eyes, Orsay) was performed to assess the cone mosaic integrity across the central retina. This is the first report on the investigation of autoimmune retinopathy using adaptive optics ophthalmoscopy. This case highlights the viability of innovative diagnostic modalities that aid early detection and subsequent management of vision threatening retinal.

  14. An approach to fabrication of large adaptive optics mirrors

    NASA Astrophysics Data System (ADS)

    Schwartz, Eric; Rey, Justin; Blaszak, David; Cavaco, Jeffrey

    2014-07-01

    For more than two decades, Northrop Grumman Xinetics has been the principal supplier of small deformable mirrors that enable adaptive optical (AO) systems for the ground-based astronomical telescope community. With today's drive toward extremely large aperture systems, and the desire of telescope designers to include adaptive optics in the main optical path of the telescope, Xinetics has recognized the need for large active mirrors with the requisite bandwidth and actuator stoke. Presented in this paper is the proposed use of Northrop Grumman Xinetics' large, ultra-lightweight Silicon Carbide substrates with surface parallel actuation of sufficient spatial density and bandwidth to meet the requirements of tomorrow's AO systems, while reducing complexity and cost.

  15. Modeling for deformable mirrors and the adaptive optics optimization program

    SciTech Connect

    Henesian, M.A.; Haney, S.W.; Trenholme, J.B.; Thomas, M.

    1997-03-18

    We discuss aspects of adaptive optics optimization for large fusion laser systems such as the 192-arm National Ignition Facility (NIF) at LLNL. By way of example, we considered the discrete actuator deformable mirror and Hartmann sensor system used on the Beamlet laser. Beamlet is a single-aperture prototype of the 11-0-5 slab amplifier design for NIF, and so we expect similar optical distortion levels and deformable mirror correction requirements. We are now in the process of developing a numerically efficient object oriented C++ language implementation of our adaptive optics and wavefront sensor code, but this code is not yet operational. Results are based instead on the prototype algorithms, coded-up in an interpreted array processing computer language.

  16. Adaptive optics at Lick Observatory: System architecture and operations

    SciTech Connect

    Brase, J.M.; An, J.; Avicola, K.

    1994-03-01

    We will describe an adaptive optics system developed for the 1 meter Nickel and 3 meter Shane telescopes at Lick Observatory. Observing wavelengths will be in the visible for the 1 meter telescope and in the near IR on the 3 meter. The adaptive optics system design is based on a 69 actuator continuous surface deformable mirror and a Hartmann wavefront sensor equipped with an intensified CCD framing camera. The system has been tested at the Cassegrain focus of the 1 meter telescope where the subaperture size is 12.5 cm. The wavefront control calculations are performed on a four processor single board computer controlled by a Unix-based system. We will describe the optical system and give details of the wavefront control system design. We will present predictions of the system performance and initial test results.

  17. Adaptive x-ray optics with a deformable mirror

    NASA Astrophysics Data System (ADS)

    Kitamoto, Shunji; Yamamoto, Norimasa; Kohmura, Takayoshi; Suga, Kazuharu; Sekiguchi, Hiroyuki; Sato, Jun'ichi; Sudo, Keisuke; Watanabe, Takeshi; Ohkubo, Youhei; Sekiguchi, Akiko; Tsujimoto, Masahiro

    2005-08-01

    We are developing a soft x-ray telescope with an adaptive optics system for future astronomical observation with very fine angular resolution of an order of milli-arc-second. From a technical point of view, we are trying to develop a normal incident telescope with multi layers. Thus the wave length is limited to be around 13.5 nm with a band pass of roughly 1nm. Since the x-ray telescope must be installed on a satellite, a stable conditions of temperature, gravity etc, can not be expected. Therefore, we investigate to use an adaptive optics system using an optical light source attached in the telescope. In this paper, we report our present status of the development. The primary mirror is an off-axis paraboloid with 80 mm effective diameter and 2 m focal length. This mirror has been coated with Mo/Si multi-layers. The reflectivity of the 13.5 nm x rays is ranging from 35% to 55%. We use a deformable mirror for the secondary mirror, which has also been coated with Mo/Si multi-layers. This mirror consists of 31 element-bimorph-piezo electrodes. The surface roughness of the mirror is ~6 nm rms. The reflectivity of the 13.5 nm x rays is roughly 65%. The adaptive optics system using an optical laser and a wave front sensor has been performed. We are using a shack-hartmann sensor (HASO 32) with a micro-lens array and a CCD. A pin hole with one micron diameter is used for the optical light source. The precision of the measurement of the wave front shape is a few nm. X-ray exposure test is now conducting, although the optical adaptive optics system is not yet installed. The x-ray detector is a back illumination CCD. The quantum efficiency for 13.5 nm x ray is ~50%. The pixel size is 24 micron square. X-ray source is an electron impact source with an Al/Si alloy target. We confirmed that the x-ray intensity around 13.55 nm is bright enough for our experiment. The imaging performance is now trying to improve and the adaptive optics system will be installed in this year.

  18. The AVES adaptive optics spectrograph for the VLT: status report

    NASA Astrophysics Data System (ADS)

    Pallavicini, Roberto; Delabre, Bernard; Pasquini, Luca; Zerbi, Filippo M.; Bonanno, Giovanni; Comari, Maurizio; Conconi, Paolo; Mazzoleni, Ruben; Santin, Paolo; Damiani, Francesco; Di Marcantonio, Paolo; Franchini, Mariagrazia; Spano, Paolo; Bonifacio, P.; Catalano, Santo; Molaro, Paolo P.; Randich, S.; Rodono, Marcello

    2003-03-01

    We report on the status of AVES, the Adaptive-optics Visual Echelle Spectrograph proposed for the secondary port of the Nasmyth Adaptive Optics System (NAOS) recently installed at the VLT. AVES is an intermediate resolution (R ≍ 16,000) high-efficiency fixed- format echelle spectrograph which operates in the spectral band 500 - 1,000 nm. In addition to a high intrinsic efficiency, comparable to that of ESI at Keck II, it takes advantage of the adaptive optics correction provided by NAOS to reduce the sky and detector contribution in background-limited observations of weak sources, thus allowing a further magnitude gain with respect to comparable non-adaptive optics spectrographs. Simulations show that the instrument will be capable of reaching a magnitude V = 22.5 at S/N > 10 in two hours, two magnitudes weaker than GIRAFFE at the same resolution and 3 magnitudes weaker than the higher resolution UVES spectrograph. Imaging and coronographic functions have also been implemented in the design. We present the results of the final design study and we dicuss the technical and operational issues related to its implementation at the VLT as a visitor instrument. We also discuss the possibility of using a scaled-up non-adaptive optics version of the same design as an element of a double- or triple-arm intermediate-resolution spectrograph for the VLT. Such an option looks attractive in the context of a high-efficiency large-bandwidth (320 - 1,500 nm) spectrograph ("fast-shooter") being considered by ESO as a 2nd-generation VLT instrument.

  19. Optic flow improves adaptability of spatiotemporal characteristics during split-belt locomotor adaptation with tactile stimulation

    PubMed Central

    Anthony Eikema, Diderik Jan A.; Chien, Jung Hung; Stergiou, Nicholas; Myers, Sara A.; Scott-Pandorf, Melissa M.; Bloomberg, Jacob J.; Mukherjee, Mukul

    2015-01-01

    Human locomotor adaptation requires feedback and feed-forward control processes to maintain an appropriate walking pattern. Adaptation may require the use of visual and proprioceptive input to decode altered movement dynamics and generate an appropriate response. After a person transfers from an extreme sensory environment and back, as astronauts do when they return from spaceflight, the prolonged period required for re-adaptation can pose a significant burden. In our previous paper, we showed that plantar tactile vibration during a split-belt adaptation task did not interfere with the treadmill adaptation however, larger overground transfer effects with a slower decay resulted. Such effects, in the absence of visual feedback (of motion) and perturbation of tactile feedback, is believed to be due to a higher proprioceptive gain because, in the absence of relevant external dynamic cues such as optic flow, reliance on body-based cues is enhanced during gait tasks through multisensory integration. In this study we therefore investigated the effect of optic flow on tactile stimulated split-belt adaptation as a paradigm to facilitate the sensorimotor adaptation process. Twenty healthy young adults, separated into two matched groups, participated in the study. All participants performed an overground walking trial followed by a split-belt treadmill adaptation protocol. The tactile group (TC) received vibratory plantar tactile stimulation only, whereas the virtual reality and tactile group (VRT) received an additional concurrent visual stimulation: a moving virtual corridor, inducing perceived self-motion. A post-treadmill overground trial was performed to determine adaptation transfer. Interlimb coordination of spatiotemporal and kinetic variables was quantified using symmetry indices, and analyzed using repeated-measures ANOVA. Marked changes of step length characteristics were observed in both groups during split-belt adaptation. Stance and swing time symmetry were

  20. Wide-field-of-view adaptive optics

    NASA Astrophysics Data System (ADS)

    Jankevics, Andrew J.; Wirth, Allan

    1992-01-01

    One of the most significant limitations to conventional atmospheric compensation systems is their very restricted field of view (FOV), generally equal to an isoplanatic patch size. A wavefront sensing and compensation concept is proposed that should allow the FOV to be increased in size by factors of ten or more. The kernel of the idea is to use wavefront measurements in several (approximately equals 9) directions separated by 100 - 200 (mu) rad to deduce an estimate of the three dimensional optical path difference (OPD) distribution in the atmosphere. The algorithms are roughly based on those used for medical tomographic imaging. Preliminary analysis indicates that from 9 measurement directions it is possible to estimate the OPD contributions from approximately six altitude layers. Once this 3-D OPD distribution is calculated, it may be used to deconvolve wide FOV short exposure images (i.e., wide FOV speckle holography) or it may be used to derive the drive signals for a suite of deformable mirrors that are conjugate to their respective altitude slices. Initial indications are that the FOV may be increased to 500 (mu) rad for a 3.5 m telescope operating at 0.8 micrometers . Further, since the OPD contribution in each layer is smaller than the full atmosphere, the requirements on the system performance are somewhat relaxed.

  1. Accuracy requirements of optical linear algebra processors in adaptive optics imaging systems

    NASA Technical Reports Server (NTRS)

    Downie, John D.; Goodman, Joseph W.

    1989-01-01

    The accuracy requirements of optical processors in adaptive optics systems are determined by estimating the required accuracy in a general optical linear algebra processor (OLAP) that results in a smaller average residual aberration than that achieved with a conventional electronic digital processor with some specific computation speed. Special attention is given to an error analysis of a general OLAP with regard to the residual aberration that is created in an adaptive mirror system by the inaccuracies of the processor, and to the effect of computational speed of an electronic processor on the correction. Results are presented on the ability of an OLAP to compete with a digital processor in various situations.

  2. Combined conjugate and pupil adaptive optics in widefield microscopy

    NASA Astrophysics Data System (ADS)

    Beaulieu, Devin R.

    Traditionally, adaptive optics (AO) systems for microscopy have focused on AO at the pupil plane, however this produces poor performance in samples with both spatially-variant aberrations, such as non-flat sample interfaces, and spatially-invariant aberrations, such as spherical aberration due to a difference between the sample index of refraction and the sample for which the objective was designed. Here, we demonstrate well-corrected, wide field-of-view (FOV) microscopy by simultaneously correcting the two types of aberrations using two AO loops. Such an approach is necessary in wide-field applications where both types of aberration may be present, as each AO loop can only fully correct one type of aberration. Wide FOV corrections are demonstrated in a trans-illumination microscope equipped with two deformable mirrors (DMs), using a partitioned aperture wavefront (PAW) sensor to directly control the DM conjugated to the sample interface and a sensor-less genetic algorithm to control the DM conjugated to the objective's pupil.

  3. Adaptive optics high resolution spectroscopy: present status and future direction

    SciTech Connect

    Alcock, C; Angel, R; Ciarlo, D; Fugate, R O; Ge, J; Kuzmenko, P; Lloyd-Hart, M; Macintosh, B; Najita, J; Woolf, N

    1999-07-27

    High resolution spectroscopy experiments with visible adaptive optics (AO) telescopes at Starfire Optical Range and Mt. Wilson have demonstrated that spectral resolution can be routinely improved by a factor of - 10 over the seeing-limited case with no extra light losses at visible wavelengths. With large CCDs now available, a very wide wavelength range can be covered in a single exposure. In the near future, most large ground-based telescopes will be equipped with powerful A0 systems. Most of these systems are aimed primarily at diffraction-limited operation in the near IR. An exciting new opportunity will thus open up for high resolution IR spectroscopy. Immersion echelle gratings with much coarser grooves being developed by us at LLNL will play a critical role in achieving high spectral resolution with a compact and low cost IR cryogenically cooled spectrograph and simultaneous large wavelength coverage on relatively small IR detectors. We have constructed a new A0 optimized spectrograph at Steward Observatory to provide R = 200,000 in the optical, which is being commissioned at the Starfire Optical Range 3.5m telescope. We have completed the optical design of the LLNL IR Immersion Spectrograph (LISPEC) to take advantage of improved silicon etching technology. Key words: adaptive optics, spectroscopy, high resolution, immersion gratings

  4. Enhanced link availability for free space optical time-frequency transfer using adaptive optic terminals

    NASA Astrophysics Data System (ADS)

    Petrillo, Keith G.; Dennis, Michael L.; Juarez, Juan C.; Souza, Katherine T.; Baumann, Esther; Bergeron, Hugo; Coddington, Ian; Deschenes, Jean-Daniel; Giorgetta, Fabrizio R.; Newbury, Nathan R.; Sinclair, Laura C.; Swann, William C.

    2016-05-01

    Optical time and frequency transfer offers extremely high precision wireless synchronization across multiple platforms for untethered distributed systems. While large apertures provide antenna gain for wireless systems which leads to robust link budgets and operation over increased distance, turbulence disrupts the beam and limits the full realization of the antenna gain. Adaptive optics can correct for phase distortions due to turbulence which potentially increases the total gain of the aperture to that for diffraction-limited operation. Here, we explore the use of adaptive optics terminals for free-space time and frequency transfer. We find that the requirement of reciprocity in a two-way time and frequency transfer link is maintained during the phase compensation of adaptive optics, and that the enhanced link budget due to aperture gain allows for potential system operation over ranges of at least tens of kilometers.

  5. Catadioptric Optics for laser Doppler velocimeter applications

    NASA Technical Reports Server (NTRS)

    Dunagan, Stephen E.

    1989-01-01

    In the design of a laser velocimeter system, attention must be given to the performance of the optical elements in their two principal tasks: focusing laser radiation into the probe volume, and collecting the scattered light. For large aperture applications, custom lens design and fabrication costs, long optical path requirements, and chromatic aberration (for two color operation) can be problematic. The adaptation of low cost Schmidt-Cassegrain astronomical telescopes to perform these laser beam manipulation and scattered light collection tasks is examined. A generic telescope design is analyzed using ray tracing and Gaussian beam propagation theory, and a simple modification procedure for converting from infinite to near unity conjugate ratio operation with image quality near the diffraction limit was identified. Modification requirements and performance are predicted for a range of geometries. Finally, a 200-mm-aperture telescope was modified for f/10 operation; performance data for this modified optic for both laser beam focusing and scattered light collection tasks agree well with predictions.

  6. Adaptive Optics System Design and Operation at Lick Observatory

    NASA Astrophysics Data System (ADS)

    Olivier, S. S.; Max, C. E.; Avicola, K.; Bissinger, H. D.; Brase, J. M.; Friedman, H. W.; Gavel, D. T.; Salmon, J. T.; Waltjen, K. E.

    1993-12-01

    An adaptive optics system developed for the 40 inch Nickel and 120 inch Shane telescopes at Lick Observatory is described. The adaptive optics system design is based on a 69 actuator continuous-surface deformable mirror and a Hartmann wavefront sensor equipped with a commercial intensified CCD fast-framing camera. The system has been tested at the Cassegrain focus of the 40 inch Nickel telescope where the subaperture diameter is 12 cm. The subaperture slope and mirror control calculations are performed on a four processor single board computer controlled by a Unix workstation. This configuration is capable of up to 1 KHz frame rates. The optical configuration of the system and its interface to the telescope is described. Details of the control system design, operation, and user interface are given. Initial test results emphasizing control system operations of this adaptive optics system using natural reference stars on the 40 inch Nickel telescope are presented. The initial test results are compared to predictions from analyses and simulations. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

  7. Adaptive optics two-photon scanning laser fluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Zhou, Yaopeng; Bifano, Thomas; Lin, Charles

    2011-03-01

    Two-photon fluorescence microscopy provides a powerful tool for deep tissue imaging. However, optical aberrations from illumination beam path limit imaging depth and resolution. Adaptive Optics (AO) is found to be useful to compensate for optical aberrations and improve image resolution and contrast from two-photon excitation. We have developed an AO system relying on a MEMS Deformable Mirror (DM) to compensate the optical aberrations in a two-photon scanning laser fluorescence microscope. The AO system utilized a Zernike polynomial based stochastic parallel gradient descent (SPGD) algorithm to optimize the DM shape for wavefront correction. The developed microscope is applied for subsurface imaging of mouse bone marrow. It was demonstrated that AO allows 80% increase in fluorescence signal intensity from bone cavities 145um below the surface. The AO-enhanced microscope provides cellular level images of mouse bone marrow at depths exceeding those achievable without AO.

  8. High-accuracy calibration of an adaptive optics system using a phase shifting diffraction interferometer

    SciTech Connect

    Bauman, B J; Campbell, E W; Olivier, S S; Sweider, D R

    1999-06-23

    A phase-shifting diffraction interferometer (PSDI) has been integrated into an adaptive optics (AO) system developed by LLNL for use on the three meter Shane telescope at Lick Observatory. The interferometer is an all fiber optic design, which is extremely compact. It is useful for calibrating the control sensors, measuring the aberrations of the entire AO optical train, and measuring the influence functions of the individual actuators on the deformable mirror. The PSDI is particularly well suited for this application because it measures converging, quasi-spherical wavefronts, such as are produced by an AO imaging system. Thus, a PSDI can be used to measure the aberrations of the entire AO system, in-situ and without errors introduced by auxiliary optics. This provides an extremely accurate measurement ({approximately} 5 nm RMS) of the optical properties of the AO system.

  9. Laser based bi-directional Gbit ground links with the Tesat transportable adaptive optical ground station

    NASA Astrophysics Data System (ADS)

    Heine, Frank; Saucke, Karen; Troendle, Daniel; Motzigemba, Matthias; Bischl, Hermann; Elser, Dominique; Marquardt, Christoph; Henninger, Hennes; Meyer, Rolf; Richter, Ines; Sodnik, Zoran

    2017-02-01

    Optical ground stations can be an alternative to radio frequency based transmit (forward) and receive (return) systems for data relay services and other applications including direct to earth optical communications from low earth orbit spacecrafts, deep space receivers, space based quantum key distribution systems and Tbps capacity feeder links to geostationary spacecrafts. The Tesat Transportable Adaptive Optical Ground Station is operational since September 2015 at the European Space Agency site in Tenerife, Spain.. This paper reports about the results of the 2016 experimental campaigns including the characterization of the optical channel from Tenerife for an optimized coding scheme, the performance of the T-AOGS under different atmospheric conditions and the first successful measurements of the suitability of the Alphasat LCT optical downlink performance for future continuous variable quantum key distribution systems.

  10. Diffractive optics: Design, fabrication, and applications

    NASA Technical Reports Server (NTRS)

    Morris, G. Michael

    1993-01-01

    The topics are presented in viewgraph form and include the following: features, applications, surface relief diffractive optics, optical data storage, waveguide lenses, diffractive lense imaging, phase grating synthesis, sub-wavelength structured surfaces, etc.

  11. Adaptive Optics Correction in Real-Time for Dynamic Wavefront Errors

    DTIC Science & Technology

    1990-03-15

    This paper reports on the principles for the use of, and the experimental results obtained from, an adaptive optics system for correcting dynamic...control system. Keywords: Adaptive optics ; Wavefront sensing; Deformable mirror; Chinese translations.

  12. Deploying the testbed for the VLT adaptive optics facility: ASSIST

    NASA Astrophysics Data System (ADS)

    Stuik, Remko; La Penna, Paolo; Dupuy, Christophe; de Haan, Menno; Arsenault, Robin; Boland, Wilfried; Elswijk, Eddy; ter Horst, Rik; Hubin, Norbert; Madec, Pierre-Yves; Molster, Frank; Wiegers, Emiel

    2012-07-01

    The ESO Very Large Telescope Adaptive Optics Facility (VLT-AOF) will transform the VLT Unit Telescope 4 to an Adaptive Telescope. In absence of an intermediate focus before the Adaptive Secondary in this Ritchey-Chrétien type telescope and in order to reduce the testing and calibration of the system on-sky, ASSIST, The Adaptive Secondary Setup and Instrument STimulator, was developed. It provides an off-sky testing facility for the ESO AOF and will provide a full testing environment for three elements of the VLT Adaptive Optics Facility: the Deformable Secondary Mirror (DSM) and the AO modules for MUSE and HAWK-I (GALACSI and GRAAL). ASSIST was delivered to ESO Garching, where it was assembled and tested. Currently ASSIST is being integrated with the Deformable Secondary Mirror, the first step in the full system testing of the two AO systems for the VLT AOF on ASSIST. This paper briefly reviews the design and properties of ASSIST and reports on the first results of ASSIST in stand-alone mode.

  13. Pixelized Device Control Actuators for Large Adaptive Optics

    NASA Technical Reports Server (NTRS)

    Knowles, Gareth J.; Bird, Ross W.; Shea, Brian; Chen, Peter

    2009-01-01

    A fully integrated, compact, adaptive space optic mirror assembly has been developed, incorporating new advances in ultralight, high-performance composite mirrors. The composite mirrors use Q-switch matrix architecture-based pixelized control (PMN-PT) actuators, which achieve high-performance, large adaptive optic capability, while reducing the weight of present adaptive optic systems. The self-contained, fully assembled, 11x11x4-in. (approx.= 28x28x10-cm) unit integrates a very-high-performance 8-in. (approx.=20-cm) optic, and has 8-kHz true bandwidth. The assembled unit weighs less than 15 pounds (=6.8 kg), including all mechanical assemblies, power electronics, control electronics, drive electronics, face sheet, wiring, and cabling. It requires just three wires to be attached (power, ground, and signal) for full-function systems integration, and uses a steel-frame and epoxied electronics. The three main innovations are: 1. Ultralightweight composite optics: A new replication method for fabrication of very thin composite 20-cm-diameter laminate face sheets with good as-fabricated optical figure was developed. The approach is a new mandrel resin surface deposition onto previously fabricated thin composite laminates. 2. Matrix (regenerative) power topology: Waveform correction can be achieved across an entire face sheet at 6 kHz, even for large actuator counts. In practice, it was found to be better to develop a quadrant drive, that is, four quadrants of 169 actuators behind the face sheet. Each quadrant has a single, small, regenerative power supply driving all 169 actuators at 8 kHz in effective parallel. 3. Q-switch drive architecture: The Q-switch innovation is at the heart of the matrix architecture, and allows for a very fast current draw into a desired actuator element in 120 counts of a MHz clock without any actuator coupling.

  14. Adaptive optics operations at the Large Binocular Telescope Observatory

    NASA Astrophysics Data System (ADS)

    Miller, Douglas L.; Taylor, Gregory; Christou, Julian C.; Zhang, Xianyu; Brusa Zappellini, Guido; Rahmer, Gustavo; Lefebvre, Michael; Puglisi, Alfio; Pinna, Enrico; Esposito, Simone

    2016-07-01

    The goal for the adaptive optics systems at the Large Binocular Telescope Observatory (LBTO) is for them to operate fully automatically, without the need for an AO Scientist, and to be run by the observers and/or the telescope operator. This has been built into their design. Initially, the AO systems would close the loop using optimal parameters based on the observing conditions and guide star brightness, without adapting to changing conditions. We present the current status of AO operations as well as recent updates that improve the operational efficiency and minimize downtime. Onsky efficiency and performance will also be presented, along with calibrations required for AO closed loop operation.

  15. A Time Integrating Optical Correlator for Adaptive Array Processing.

    DTIC Science & Technology

    1982-12-01

    AD-A124 672 A TIME INTEGRATING OPT1CRL CORRELATOR FOR ADAPTIVE / RRAYV PROCESSING(U) AIR FORCE INST OF TECH IRIGHT-PATTERSON AFB OH SCHOOL OF...di3tdbutbon i- , " . DEPARTMENT OF THE AIR FORCE aAIR UNIVERSITY (ATC) AIR FORCE INSTITUTE OF TECHNOLOGY LUJ._ Wright-Patterson Air Force Base, Ohio 8 3 02...OPTICAL CORRELATOR FOR ADAPTIVE ARRAY PROCESSING THESIS Presented to the Faculty of the School of Engineering of the Air Force Institute of Technology Air

  16. Adaptive optics capabilities at the Large Binocular Telescope Observatory

    NASA Astrophysics Data System (ADS)

    Christou, J. C.; Brusa, G.; Conrad, A.; Esposito, S.; Herbst, T.; Hinz, P.; Hill, J. M.; Miller, D. L.; Rabien, S.; Rahmer, G.; Taylor, G. E.; Veillet, C.; Zhang, X.

    2016-07-01

    We present an overview of the current and future adaptive optics systems at the LBTO along with the current and planned science instruments they feed. All the AO systems make use of the two 672 actuator adaptive secondary mirrors. They are (1) FLAO (NGS/SCAO) feeding the LUCI NIR imagers/spectrographs; (2) LBTI/AO (NGS/SCAO) feeding the NIR/MIR imagers and LBTI beam combiner; (3) the ARGOS LGS GLAO system feeding LUCIs; and (4) LINC-NIRVANA - an NGS/MCAO imager and interferometer system. AO performance of the current systems is presented along with proposed performances for the newer systems taking into account the future instrumentation.

  17. Fast calibration of high-order adaptive optics systems.

    PubMed

    Kasper, Markus; Fedrigo, Enrico; Looze, Douglas P; Bonnet, Henri; Ivanescu, Liviu; Oberti, Sylvain

    2004-06-01

    We present a new method of calibrating adaptive optics systems that greatly reduces the required calibration time or, equivalently, improves the signal-to-noise ratio. The method uses an optimized actuation scheme with Hadamard patterns and does not scale with the number of actuators for a given noise level in the wavefront sensor channels. It is therefore highly desirable for high-order systems and/or adaptive secondary systems on a telescope without a Gregorian focal plane. In the latter case, the measurement noise is increased by the effects of the turbulent atmosphere when one is calibrating on a natural guide star.

  18. Adaptive optics confocal microscopy using direct wavefront sensing.

    PubMed

    Tao, Xiaodong; Fernandez, Bautista; Azucena, Oscar; Fu, Min; Garcia, Denise; Zuo, Yi; Chen, Diana C; Kubby, Joel

    2011-04-01

    Optical aberrations due to the inhomogeneous refractive index of tissue degrade the resolution and brightness of images in deep-tissue imaging. We introduce a confocal fluorescence microscope with adaptive optics, which can correct aberrations based on direct wavefront measurements using a Shack-Hartmann wavefront sensor with a fluorescent bead used as a point source reference beacon. The results show a 4.3× improvement in the Strehl ratio and a 240% improvement in the signal intensity for fixed mouse tissues at depths of up to 100 μm.

  19. Bimorph mirrors for adaptive optics in space telescopes

    NASA Astrophysics Data System (ADS)

    Alaluf, D.; Bastaits, R.; Wang, K.; Horodinca, M.; Burda, I.; Martic, G.; Preumont, A.

    2016-07-01

    This paper discusses a concept of bimorph deformable mirror used in adaptive optics to compensate for manufacturing errors, gravity release and thermal distortion affecting large lightweight mirrors in space telescopes. The mirror consists of a single-crystal Silicon wafer (D=75 mm t=500μm) covered with an optical coating on the front side and an array of 25 independent PZT actuators acting in d31 mode on the back side. The mirror is mounted on an isostatic support with three linear PZT actuators controlling the rigid-body motion. The paper presents the experimental results obtained with this design and a new, more compact alternative.

  20. Adaptive optical imaging through complex living plant cells

    NASA Astrophysics Data System (ADS)

    Tamada, Yosuke; Hayano, Yutaka; Murata, Takashi; Oya, Shin; Honma, Yusuke; Kanazawa, Minoru; Miura, Noriaki; Hasebe, Mitsuyasu; Kamei, Yasuhiro; Hattori, Masayuki

    2017-04-01

    Live-cell imaging using fluorescent molecules is now essential for biological researches. However, images of living cells are accompanied with blur, which becomes stronger according to the depth inside the cells and tissues. This image blur is caused by the disturbance on light that goes through optically inhomogeneous living cells and tissues. Here, we show adaptive optics (AO) imaging of living plant cells. AO has been developed in astronomy to correct the disturbance on light caused by atmospheric turbulence. We developed AO microscope effective for the observation of living plant cells with strong disturbance by chloroplasts, and successfully obtained clear images inside plant cells.

  1. Adaptive Optics for Industry and Medicine International Workshop.

    DTIC Science & Technology

    1998-01-07

    81-6-877-0900, e-mail: yoon@ile.osaka-u.ac.jp. 17. Victor I. Shmalhausen, International Laser Center, Moscow State University, Vorob’evy Gory,t 119899... Manuel Toledo- Quinones 3 Adaptive Optics Associates 54 CambridgePark Drive 3 Cambridge, MA 02140 (617)864-0201 (voice) * (617)864-1348 (fax) marty...maximum value) I LSE References: ST. Luna , "Linear Stochastic Estimation of Optical Beam Deflection through a Heated Round Turbulent Jet," MS Thesis

  2. Adaptive optics for improved retinal surgery and diagnostics

    SciTech Connect

    Humayun, M S; Sadda, S R; Thompson, C A; Olivier, S S; Kartz, M W

    2000-08-21

    It is now possible to field a compact adaptive optics (AO) system on a surgical microscope for use in retinal diagnostics and surgery. Recent developments in integrated circuit technology and optical photonics have led to the capability of building an AO system that is compact and significantly less expensive than traditional AO systems. It is foreseen that such an AO system can be integrated into a surgical microscope while maintaining a package size of a lunchbox. A prototype device can be developed in a manner that lends itself well to large-scale manufacturing.

  3. A novel data adaptive detection scheme for distributed fiber optic acoustic sensing

    NASA Astrophysics Data System (ADS)

    Ölçer, Íbrahim; Öncü, Ahmet

    2016-05-01

    We introduce a new approach for distributed fiber optic sensing based on adaptive processing of phase sensitive optical time domain reflectometry (Φ-OTDR) signals. Instead of conventional methods which utilizes frame averaging of detected signal traces, our adaptive algorithm senses a set of noise parameters to enhance the signal-to-noise ratio (SNR) for improved detection performance. This data set is called the secondary data set from which a weight vector for the detection of a signal is computed. The signal presence is sought in the primary data set. This adaptive technique can be used for vibration detection of health monitoring of various civil structures as well as any other dynamic monitoring requirements such as pipeline and perimeter security applications.

  4. Adaptive Optics Control Strategies for Extremely Large Telescopes

    SciTech Connect

    Gavel, D T

    2001-07-26

    Adaptive optics for the 30-100 meter class telescopes now being considered will require an extension in almost every area of AO system component technology. In this paper, we present scaling laws and strawman error budgets for AO systems on extremely large telescopes (ELTs) and discuss the implications for component technology and computational architecture. In the component technology area, we discuss the advanced efforts being pursued at the NSF Center for Adaptive Optics (CfAO) in the development of large number of degrees of freedom deformable mirrors, wavefront sensors, and guidestar lasers. It is important to note that the scaling of present wavefront reconstructor algorithms will become computationally intractable for ELTs and will require the development of new algorithms and advanced numerical mathematics techniques. We present the computational issues and discuss the characteristics of new algorithmic approaches that show promise in scaling to ELT AO systems.

  5. Neptune and Titan Observed with Keck Telescope Adaptive Optics

    SciTech Connect

    Max, C.E.; Macintosh, B.A.; Gibbard, S.; Gavel, D.T.; Roe, H.; De Pater, I.; Ghez, A.M.; Acton, S.; Wizinowich, P.L.; Lai, O.

    2000-05-05

    The authors report on observations taken during engineering science validation time using the new adaptive optics system at the 10-m Keck II Telescope. They observe Neptune and Titan at near-infrared wavelengths. These objects are ideal for adaptive optics imaging because they are bright and small, yet have many diffraction-limited resolution elements across their disks. In addition Neptune and Titan have prominent physical features, some of which change markedly with time. They have observed infrared-bright storms on Neptune, and very low-albedo surface regions on Titan, Saturn's largest moon, Spatial resolution on Neptune and Titan was 0.05-0.06 and 0.04-0.05 arc sec, respectively.

  6. Adaptive Optics Performance at Lick and Keck Observatory

    NASA Astrophysics Data System (ADS)

    Max, C. E.; Olivier, S. S.; Avicola, K.; Bissinger, H. D.; Brase, J. M.; Friedman, H. W.; Gavel, D. T.; Salmon, J. T.; Waltjen, K. E.

    1993-12-01

    The performance of an adaptive optics system developed for the 40 inch Nickel and 120 inch Shane telescopes at Lick Observatory is discussed. The system is based on a 69 actuator continuous-surface deformable mirror and a Hartmann wavefront sensor equipped with a commercial intensified CCD fast-framing camera. Results from tests of this adaptive optics system using natural reference stars on the 40 inch Nickel telescope are presented. These results are compared to the performance predicted by simulations and analyses. Predictions for the system performance on the 120 inch Shane telescope and on the 10 meter Keck telescope using both natural and laser reference stars are also presented. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

  7. Time-sharing wave-front-sensing adaptive optics.

    PubMed

    Hou, Jing

    2004-02-01

    Based on the concept of common-path/common-mode adaptive optics, the time-sharing wave-front-sensing adaptive optics system contains only one Hartmann-Shack (H-S) wave-front sensor, which detects two aberrations in the beam path alternately. After data fusion of the two aberrations, the actuator voltage of the deformable mirror (DM) is obtained. How the disturbances of the slope data and the response matrix influence the DM's actuator voltage in the data fusion methods is discussed, and the effective upper limits are given. Feasible data fusion methods are tested, and experiments verify that the performance of the system is good. The time-sharing technique is limited in sampling rate and is suitable only for corrections of slowly changing phases, because the H-S wave-front sensor's sampling frequency must be adequate for the alternate detection of two aberrations.

  8. Neptune and Titan observed with Keck Telescope adaptive optics

    NASA Astrophysics Data System (ADS)

    Max, Claire E.; Macintosh, Bruce A.; Gibbard, Seran; Gavel, Donald T.; Roe, Henry; de Pater, Imke; Ghez, Andrea M.; Acton, Scott; Wizinowich, Peter L.; Lai, Olivier

    2000-07-01

    We report on observations taken during engineering science validation time using the new adaptive optics system at the 10-m Keck II Telescope. We observed Neptune and Titan at near- infrared wavelengths. These objects are ideal for adaptive optics imaging because they are bright and small, yet have many diffraction-limited resolution elements across their disks. In addition Neptune and Titan have prominent physical features, some of which change markedly with time. We have observed infrared-bright 'storms' on Neptune, and very low- albedo surface regions on Titan, Saturn's largest moon. Spatial resolution on Neptune and Titan was 0.05 - 0.06 and 0.04 - 0.05 arc sec, respectively.

  9. Contrast-based sensorless adaptive optics for retinal imaging.

    PubMed

    Zhou, Xiaolin; Bedggood, Phillip; Bui, Bang; Nguyen, Christine T O; He, Zheng; Metha, Andrew

    2015-09-01

    Conventional adaptive optics ophthalmoscopes use wavefront sensing methods to characterize ocular aberrations for real-time correction. However, there are important situations in which the wavefront sensing step is susceptible to difficulties that affect the accuracy of the correction. To circumvent these, wavefront sensorless adaptive optics (or non-wavefront sensing AO; NS-AO) imaging has recently been developed and has been applied to point-scanning based retinal imaging modalities. In this study we show, for the first time, contrast-based NS-AO ophthalmoscopy for full-frame in vivo imaging of human and animal eyes. We suggest a robust image quality metric that could be used for any imaging modality, and test its performance against other metrics using (physical) model eyes.

  10. Next generation high resolution adaptive optics fundus imager

    NASA Astrophysics Data System (ADS)

    Fournier, P.; Erry, G. R. G.; Otten, L. J.; Larichev, A.; Irochnikov, N.

    2005-12-01

    The spatial resolution of retinal images is limited by the presence of static and time-varying aberrations present within the eye. An updated High Resolution Adaptive Optics Fundus Imager (HRAOFI) has been built based on the development from the first prototype unit. This entirely new unit was designed and fabricated to increase opto-mechanical integration and ease-of-use through a new user interface. Improved camera systems for the Shack-Hartmann sensor and for the scene image were implemented to enhance the image quality and the frequency of the Adaptive Optics (AO) control loop. An optimized illumination system that uses specific wavelength bands was applied to increase the specificity of the images. Sample images of clinical trials of retinas, taken with and without the system, are shown. Data on the performance of this system will be presented, demonstrating the ability to calculate near diffraction-limited images.

  11. MEMS-based extreme adaptive optics for planet detection

    SciTech Connect

    Macintosh, B A; Graham, J R; Oppenheimer, B; Poyneer, L; Sivaramakrishnan, A; Veran, J

    2005-11-18

    The next major step in the study of extrasolar planets will be the direct detection, resolved from their parent star, of a significant sample of Jupiter-like extrasolar giant planets. Such detection will open up new parts of the extrasolar planet distribution and allow spectroscopic characterization of the planets themselves. Detecting Jovian planets at 5-50 AU scale orbiting nearby stars requires adaptive optics systems and coronagraphs an order of magnitude more powerful than those available today--the realm of ''Extreme'' adaptive optics. We present the basic requirements and design for such a system, the Gemini Planet Imager (GPI.) GPI will require a MEMS-based deformable mirror with good surface quality, 2-4 micron stroke (operated in tandem with a conventional low-order ''woofer'' mirror), and a fully-functional 48-actuator-diameter aperture.

  12. Atmospheric dispersion in very large telescopes with adaptive optics

    NASA Astrophysics Data System (ADS)

    Wynne, Charles G.

    1997-02-01

    Current work on correcting the effects of atmospheric turbulence on telescope imagery, so as to approach the diffraction limit, requires attention to related effects to exploit it fully. In particular adaptive optics, which acts by means of a flexible mirror, is therefore colour-blind, and requires a hitherto unknown level of correction of atmospheric dispersion if it is to be used more than a few degrees from zenith. Adaptive optics can only operate over a very limited field angle and wavelength range. Fine fast auto-guiding can give substantially improved imagery, over wider field angles and wavelength range, requiring higher performance dispersion correctors than heretofore. This note describes a dispersion corrector to meet both these needs.

  13. Contrast-based sensorless adaptive optics for retinal imaging

    PubMed Central

    Zhou, Xiaolin; Bedggood, Phillip; Bui, Bang; Nguyen, Christine T.O.; He, Zheng; Metha, Andrew

    2015-01-01

    Conventional adaptive optics ophthalmoscopes use wavefront sensing methods to characterize ocular aberrations for real-time correction. However, there are important situations in which the wavefront sensing step is susceptible to difficulties that affect the accuracy of the correction. To circumvent these, wavefront sensorless adaptive optics (or non-wavefront sensing AO; NS-AO) imaging has recently been developed and has been applied to point-scanning based retinal imaging modalities. In this study we show, for the first time, contrast-based NS-AO ophthalmoscopy for full-frame in vivo imaging of human and animal eyes. We suggest a robust image quality metric that could be used for any imaging modality, and test its performance against other metrics using (physical) model eyes. PMID:26417525

  14. Nanolubrication of sliding components in adaptive optics used in microprojectors

    NASA Astrophysics Data System (ADS)

    Bhushan, Bharat; Lee, Hyungoo; Chaparala, Satish C.; Bhatia, Vikram

    2010-10-01

    Integrated microprojectors are being developed to project a large image on any surface chosen by the users. For a laser-based microprojector, a piezo-electric based adaptive optics unit is adopted in the green laser architecture. The operation of this unit depends on stick-slip motion between the sliding components. Nanolubrication of adaptive optics sliding components is needed to reduce wear and for smooth operation. In this study, a methodology to measure lubricant thickness distribution with a nanoscale resolution is developed. Friction, adhesion, and wear mechanisms of lubricant on the sliding components are studied. Effect of actual composite components, scan direction, scale effect, temperature, and humidity to correlate AFM data with the microscale device performance is studied.

  15. Dynamic optical aberration correction with adaptive coded apertures techniques in conformal imaging

    NASA Astrophysics Data System (ADS)

    Li, Yan; Hu, Bin; Zhang, Pengbin; Zhang, Binglong

    2015-02-01

    Conformal imaging systems are confronted with dynamic aberration in optical design processing. In classical optical designs, for combination high requirements of field of view, optical speed, environmental adaption and imaging quality, further enhancements can be achieved only by the introduction of increased complexity of aberration corrector. In recent years of computational imaging, the adaptive coded apertures techniques which has several potential advantages over more traditional optical systems is particularly suitable for military infrared imaging systems. The merits of this new concept include low mass, volume and moments of inertia, potentially lower costs, graceful failure modes, steerable fields of regard with no macroscopic moving parts. Example application for conformal imaging system design where the elements of a set of binary coded aperture masks are applied are optimization designed is presented in this paper, simulation results show that the optical performance is closely related to the mask design and the reconstruction algorithm optimization. As a dynamic aberration corrector, a binary-amplitude mask located at the aperture stop is optimized to mitigate dynamic optical aberrations when the field of regard changes and allow sufficient information to be recorded by the detector for the recovery of a sharp image using digital image restoration in conformal optical system.

  16. The fundus photo has met its match: optical coherence tomography and adaptive optics ophthalmoscopy are here to stay.

    PubMed

    Morgan, Jessica I W

    2016-05-01

    Over the past 25 years, optical coherence tomography (OCT) and adaptive optics (AO) ophthalmoscopy have revolutionised our ability to non-invasively observe the living retina. The purpose of this review is to highlight the techniques and human clinical applications of recent advances in OCT and adaptive optics scanning laser/light ophthalmoscopy (AOSLO) ophthalmic imaging. Optical coherence tomography retinal and optic nerve head (ONH) imaging technology allows high resolution in the axial direction resulting in cross-sectional visualisation of retinal and ONH lamination. Complementary AO ophthalmoscopy gives high resolution in the transverse direction resulting in en face visualisation of retinal cell mosaics. Innovative detection schemes applied to OCT and AOSLO technologies (such as spectral domain OCT, OCT angiography, confocal and non-confocal AOSLO, fluorescence, and AO-OCT) have enabled high contrast between retinal and ONH structures in three dimensions and have allowed in vivo retinal imaging to approach that of histological quality. In addition, both OCT and AOSLO have shown the capability to detect retinal reflectance changes in response to visual stimuli, paving the way for future studies to investigate objective biomarkers of visual function at the cellular level. Increasingly, these imaging techniques are being applied to clinical studies of the normal and diseased visual system. Optical coherence tomography and AOSLO technologies are capable of elucidating the structure and function of the retina and ONH noninvasively with unprecedented resolution and contrast. The techniques have proven their worth in both basic science and clinical applications and each will continue to be utilised in future studies for many years to come. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

  17. Applications Of Diamond In Optics

    NASA Astrophysics Data System (ADS)

    Seal, M.; van Enckevort, W. J. P.

    1989-01-01

    This paper reviews existing and new applications of single crystal diamond, both natural and synthetic, in optical science. The traditional application is as transmissive components, making use of the very wide spectral transmission range, high thermal conductivity, and chemical inertness of diamond. Diamond windows for corrosive environments are well known; diamond surgical endoscope components are under development; and the use of sharpened diamonds as combined surgical cutting instruments and light pipes for internal illumination of the edge is commercial reality. The superb ability of diamond to conduct heat, combined with its very low thermal expansion coefficient makes it suitable for the transmission of high power laser energy, though there is a problem currently being addressed of a high surface reflection coefficient. It is very probable that CVD diamond-like films will form good anti-reflection coatings for diamond. In new applications, the technology of making diamond lenses is being developed. The use of diamond as a detector of ionising radiation is well known, but recent work shows its possibilities in thermoluminescent as well as conduction and pulse counting modes. There are further possibilities of using diamond for the detection and measurement of optical radiation. Examples are low, medium, and high intensity far ultraviolet (< 225 nm) and very high intensity near ultraviolet and visible light from excimer, dye, or argon lasers. Diamond is very radiation resistant! Sensitivities, response times and impurity trap levels have been measured and appropriate diamonds can be synthesised. The use of diamond as fast opto-electronic switches has been reported in the literature and the mechanical and thermal design of diamond "heat sink" substrates for semiconductor laser diodes is advancing rapidly.

  18. Performance of a MEMS-base Adaptive Optics Optical Coherency Tomography System

    SciTech Connect

    Evans, J; Zadwadzki, R J; Jones, S; Olivier, S; Opkpodu, S; Werner, J S

    2008-01-16

    We have demonstrated that a microelectrical mechanical systems (MEMS) deformable mirror can be flattened to < 1 nm RMS within controllable spatial frequencies over a 9.2-mm aperture making it a viable option for high-contrast adaptive optics systems (also known as Extreme Adaptive Optics). The Extreme Adaptive Optics Testbed at UC Santa Cruz is being used to investigate and develop technologies for high-contrast imaging, especially wavefront control. A phase shifting diffraction interferometer (PSDI) measures wavefront errors with sub-nm precision and accuracy for metrology and wavefront control. Consistent flattening, required testing and characterization of the individual actuator response, including the effects of dead and low-response actuators. Stability and repeatability of the MEMS devices was also tested. An error budget for MEMS closed loop performance will summarize MEMS characterization.

  19. High-resolution adaptive optics findings in talc retinopathy.

    PubMed

    Soliman, Mohamed K; Sarwar, Salman; Hanout, Mostafa; Sadiq, Mohammad A; Agarwal, Aniruddha; Gulati, Vikas; Nguyen, Quan Dong; Sepah, Yasir J

    2015-01-01

    Talc retinopathy is a recognized ocular condition characterized by the presence of small, yellow, glistening crystals found inside small retinal vessels and within different retinal layers. These crystals can be associated with retinal vascular occlusion and ischemia. Different diagnostic modalities have been used previously to characterize the retinal lesions in talc retinopathy. Adaptive optics, a high resolution imaging technique, is used to evaluate the location, appearance and distribution of talc crystals in a case of talc retinopathy.

  20. Precision Targeting With a Tracking Adaptive Optics Scanning Laser Ophthalmoscope

    DTIC Science & Technology

    2006-01-01

    galvanometers placed at appropriate conjugates within the path of the adaptive optics scanning laser ophthalmoscope. The input to the “master” control loop is...loop is the scaled position signals from the master galvanometers . The slave tracking mirrors are placed at conjugates to the center of rotation of the...slave systems), and analog-to-digital and digital-to- analog converters (ADC and DACs) to receive reflectometer signals and drive galvanometers . The

  1. 3D adaptive optics in a light sheet microscope.

    PubMed

    Bourgenot, Cyril; Saunter, Christopher D; Taylor, Jonathan M; Girkin, John M; Love, Gordon D

    2012-06-04

    We report on a single plane illumination microscope (SPIM) incorporating adaptive optics in the imaging arm. We show how aberrations can occur from the sample mounting tube and quantify the aberrations both experimentally and computationally. A wavefront sensorless approach was taken to imaging a green fluorescent protein (GFP) labelled transgenic zebrafish. We show improvements in image quality whilst recording a 3D "z-stack" and show how the aberrations come from varying depths in the fish.

  2. Limits of spherical blur determined with an adaptive optics mirror.

    PubMed

    Atchison, David A; Guo, Huanqing; Fisher, Scott W

    2009-05-01

    We extended an earlier study (Vision Research, 45, 1967-1974, 2005) in which we investigated limits at which induced blur of letter targets becomes noticeable, troublesome and objectionable. Here we used a deformable adaptive optics mirror to vary spherical defocus for conditions of a white background with correction of astigmatism; a white background with reduction of all aberrations other than defocus; and a monochromatic background with reduction of all aberrations other than defocus. We used seven cyclopleged subjects, lines of three high-contrast letters as targets, 3-6 mm artificial pupils, and 0.1-0.6 logMAR letter sizes. Subjects used a method of adjustment to control the defocus component of the mirror to set the 'just noticeable', 'just troublesome' and 'just objectionable' defocus levels. For the white-no adaptive optics condition combined with 0.1 logMAR letter size, mean 'noticeable' blur limits were +/-0.30, +/-0.24 and +/-0.23 D at 3, 4 and 6 mm pupils, respectively. White-adaptive optics and monochromatic-adaptive optics conditions reduced blur limits by 8% and 20%, respectively. Increasing pupil size from 3-6 mm decreased blur limits by 29%, and increasing letter size increased blur limits by 79%. Ratios of troublesome to noticeable, and of objectionable to noticeable, blur limits were 1.9 and 2.7 times, respectively. The study shows that the deformable mirror can be used to vary defocus in vision experiments. Overall, the results of noticeable, troublesome and objectionable blur agreed well with those of the previous study. Attempting to reduce higher-order aberrations or chromatic aberrations, reduced blur limits to only a small extent.

  3. Adaptive optics enables 3D STED microscopy in aberrating specimens

    PubMed Central

    Gould, Travis J.; Burke, Daniel; Bewersdorf, Joerg; Booth, Martin J.

    2012-01-01

    Stimulated emission depletion (STED) microscopy allows fluorescence far-field imaging with diffraction-unlimited resolution. Unfortunately, extending this technique to three-dimensional (3D) imaging of thick specimens has been inhibited by sample-induced aberrations. Here we present the first implementation of adaptive optics in STED microscopy to allow 3D super-resolution imaging in strongly aberrated imaging conditions, such as those introduced by thick biological tissue. PMID:23037223

  4. Adaptive optics for reduced threshold energy in femtosecond laser induced optical breakdown in water based eye model

    NASA Astrophysics Data System (ADS)

    Hansen, Anja; Krueger, Alexander; Ripken, Tammo

    2013-03-01

    In ophthalmic microsurgery tissue dissection is achieved using femtosecond laser pulses to create an optical breakdown. For vitreo-retinal applications the irradiance distribution in the focal volume is distorted by the anterior components of the eye causing a raised threshold energy for breakdown. In this work, an adaptive optics system enables spatial beam shaping for compensation of aberrations and investigation of wave front influence on optical breakdown. An eye model was designed to allow for aberration correction as well as detection of optical breakdown. The eye model consists of an achromatic lens for modeling the eye's refractive power, a water chamber for modeling the tissue properties, and a PTFE sample for modeling the retina's scattering properties. Aberration correction was performed using a deformable mirror in combination with a Hartmann-Shack-sensor. The influence of an adaptive optics aberration correction on the pulse energy required for photodisruption was investigated using transmission measurements for determination of the breakdown threshold and video imaging of the focal region for study of the gas bubble dynamics. The threshold energy is considerably reduced when correcting for the aberrations of the system and the model eye. Also, a raise in irradiance at constant pulse energy was shown for the aberration corrected case. The reduced pulse energy lowers the potential risk of collateral damage which is especially important for retinal safety. This offers new possibilities for vitreo-retinal surgery using femtosecond laser pulses.

  5. Enhancing image quality in cleared tissue with adaptive optics

    NASA Astrophysics Data System (ADS)

    Reinig, Marc R.; Novak, Samuel W.; Tao, Xiaodong; Bentolila, Laurent A.; Roberts, Dustin G.; MacKenzie-Graham, Allan; Godshalk, Sirie E.; Raven, Mary A.; Knowles, David W.; Kubby, Joel

    2016-12-01

    Our ability to see fine detail at depth in tissues is limited by scattering and other refractive characteristics of the tissue. For fixed tissue, we can limit scattering with a variety of clearing protocols. This allows us to see deeper but not necessarily clearer. Refractive aberrations caused by the bulk index of refraction of the tissue and its variations continue to limit our ability to see fine detail. Refractive aberrations are made up of spherical and other Zernike modes, which can be significant at depth. Spherical aberration that is common across the imaging field can be corrected using an objective correcting collar, although this can require manual intervention. Other aberrations may vary across the imaging field and can only be effectively corrected using adaptive optics. Adaptive optics can also correct other aberrations simultaneously with the spherical aberration, eliminating manual intervention and speeding imaging. We use an adaptive optics two-photon microscope to examine the impact of the spherical and higher order aberrations on imaging and contrast the effect of compensating only for spherical aberration against compensating for the first 22 Zernike aberrations in two tissue types. Increase in image intensity by 1.6× and reduction of root mean square error by 3× are demonstrated.

  6. Coronagraphy with the AEOS High Order Adaptive Optics System

    NASA Astrophysics Data System (ADS)

    Lloyd, J. P.; Graham, J. R.; Kalas, P.; Oppenheimer, B. R.; Sivaramakrishnan, A.; Makidon, R. B.; Macintosh, B. A.; Max, C. E.; Baudoz, P.; Kuhn, J. R.; Potter, D.

    2001-05-01

    Adaptive Optics has recently become a widely used technique to acquire sensitive, diffraction limited images in the near infrared with large ground based telescopes. Most astronomical targets are faint; driving astronomical AO systems towards large subapertures; resulting in a compromise between guide star brightness, observing wavelength, resolution and Strehl ratio. Space surveilance systems have recently been developed that exploit high order adaptive optics systems to take diffraction limited images in visible light on 4 meter class telescopes on bright (V<8) targets. There is, however, a particular niche that can be exploited by turning these visible light space surveillance systems to astronomical use at infrared wavelengths. At the longer wavelengths, the strehl ratio rises dramatically, thus placing more light into the diffracted Airy pattern at the expense of the atmospheric halo. A coronagraph can be used to suppress the diffracted light, and observe faint companions and debris disks around nearby, bright stars. Observations of these very high contrast objects benefit greatly from much higher order adaptive optics systems than are presently available to the astronomical commnunity. The National Science Foundation and Air Force Office of Scientific Research is sponsoring a program to conduct astronomical observations at the AEOS facility. We are presently developing an astronomical coronagraph to be deployed at the Air Force AEOS facility. We describe the coronagraph, and discuss the advantages and limitations of ground based high order AO for high contrast imaging.

  7. Astronomical coronagraphy with high-order adaptive optics systems

    NASA Astrophysics Data System (ADS)

    Lloyd, James P.; Graham, James R.; Kalas, Paul; Oppenheimer, Ben R.; Sivaramakrishnan, Anand; Makidon, Russell B.; Macintosh, Bruce A.; Max, Claire E.; Baudoz, Pierre; Kuhn, Jeff R.; Potter, Dan

    2001-12-01

    Space surveillance systems have recently been developed that exploit high order adaptive optics systems to take diffraction limited images in visible light on 4 meter class telescopes. Most astronomical targets are faint, thus driving astronomical AO systems towards larger subapertures, and thus longer observing wavelengths for diffraction limited imaging at moderate Strehl ratio. There is, however, a particular niche that can be exploited by turning these visible light space surveillance systems to astronomical use at infrared wavelengths. At the longer wavelengths, the Strehl ratio rises dramatically, thus placing more light into the diffracted Airy pattern compared to the atmospheric halo. A Lyot coronagraph can be used to suppress the diffracted light from an on axis star, and observe faint companions and debris disks around nearby, bright stars. These very high contrast objects can only be observed with much higher order adaptive optics systems than are presently available to the astronomical community. We describe simulations of high order adaptive optics coronagraphs, and outline a project to deploy an astronomical coronagraph at the Air Force AEOS facility at the Maui Space Surveillance System.

  8. Retinal imaging system with adaptive optics enhanced with pupil tracking

    NASA Astrophysics Data System (ADS)

    Sahin, Betul; Lamory, Barbara; Levecq, Xavier; Vabre, Laurent; Dainty, Chris

    2011-03-01

    A compact retinal camera with adaptive optics which was designed for clinical practice was used to test a new adaptive optics control algorithm to correct for the angular ray deviations of a model eye. The new control algorithm is based on pupil movements rather than the measurement of the slopes of the wavefront with an optoelectronic sensor. The method for the control algorithm was based on the hypothesis that majority of the changes of the aberrations of the eye are due to head and eye movements and it is possible to correct for the aberrations of the eye by shifting the paraxial correction according to the new position of the pupil. Since the fixational eye movements are very small, the eye movements are assumed to be translational rather than rotational. Using the new control algorithm it was possible to simulate the aberrations of the moving model eye based on pupil tracking. The RMS of the residual wavefront error of the simulation had a magnitude similar to the RMS of the residual wavefront error of the adaptive optics correction based on optoelectronic sensor for angular ray deviations. If our hypothesis is true and other factors such as the tear film or the crystalline lens fluctuations do not cause changes in the aberrations of the eye as much as motion does, the method is expected to work in vivo as it did for a model eye which had no intrinsic factors that cause aberration changes.

  9. Enhancing image quality in cleared tissue with adaptive optics.

    PubMed

    Reinig, Marc R; Novak, Samuel W; Tao, Xiaodong; Bentolila, Laurent A; Roberts, Dustin G; MacKenzie-Graham, Allan; Godshalk, Sirie E; Raven, Mary A; Knowles, David W; Kubby, Joel

    2016-12-01

    Our ability to see fine detail at depth in tissues is limited by scattering and other refractive characteristics of the tissue. For fixed tissue, we can limit scattering with a variety of clearing protocols. This allows us to see deeper but not necessarily clearer. Refractive aberrations caused by the bulk index of refraction of the tissue and its variations continue to limit our ability to see fine detail. Refractive aberrations are made up of spherical and other Zernike modes, which can be significant at depth. Spherical aberration that is common across the imaging field can be corrected using an objective correcting collar, although this can require manual intervention. Other aberrations may vary across the imaging field and can only be effectively corrected using adaptive optics. Adaptive optics can also correct other aberrations simultaneously with the spherical aberration, eliminating manual intervention and speeding imaging. We use an adaptive optics two-photon microscope to examine the impact of the spherical and higher order aberrations on imaging and contrast the effect of compensating only for spherical aberration against compensating for the first 22 Zernike aberrations in two tissue types. Increase in image intensity by 1.6× and reduction of root mean square error by 3× are demonstrated.

  10. Adaptive optics simulation of intraocular lenses with modified spherical aberration.

    PubMed

    Piers, Patricia A; Fernandez, Enrique J; Manzanera, Silvestre; Norrby, Sverker; Artal, Pablo

    2004-12-01

    Adaptive optics systems can be used to investigate the potential visual benefit associated with correcting ocular wave-front aberration. In this study, adaptive optics techniques were used to evaluate the potential advantages and disadvantages associated with intraocular lenses (IOLs) with modified spherical aberration profiles. An adaptive optics vision simulator was constructed that allows psychophysical tests to be performed while viewing targets through any desired ocular wave-front profile. With this simulator, the subjective visual performance of four subjects was assessed by letter acuity and contrast sensitivity (at 3, 6, and 15 cyc/deg) for two different values of induced spherical aberration. The values of spherical aberration were chosen to reproduce two conditions: the average amount measured in pseudophakic patients with implanted IOLs having spherical surfaces and the complete correction of the individual's spherical aberration. Visual performance was assessed in both white and green light, at best focus and for defocus of +/-0.5 and +/-1.0 D. There was an average improvement in visual acuity associated with the correction of spherical aberration of 10% and 38% measured in white and green light, respectively. Similarly, average contrast sensitivity measurements improved 32% and 57% in white and green light. When spherical aberration was corrected, visual performance was as good as or better than for the normal spherical aberration case for defocus as large as +/-1 D. Correcting ocular spherical aberration improves spatial vision in the best-focus position without compromising the subjective tolerance to defocus.

  11. Coherence gating and adaptive optics in the eye

    NASA Astrophysics Data System (ADS)

    Miller, Donald T.; Qu, Junle; Jonnal, Ravi S.; Thorn, Karen E.

    2003-07-01

    An en face coherence gated camera equipped with adaptive optics (AO) has been constructed for imaging single cells in the living human retina. The high axial resolution of coherence gating combined with the high transverse resolution of AO provides a powerful imaging tool whose image quality can surpass either methodology performing alone. The AO system relies on a 37-actuator Xinetics mirror and a Shack-Hartmann wavefront sensor that executes up to 22 corrections per second. The coherence gate is realized with a free-space Michelson interferometer that employs a scientific-grade 12-bit CCD array for recording 2-D retinal interferograms. Images were collected of microstructures the size of single cells in the in vivo retina. Early results suggest that a coherence gated adaptive optics camera should substantially improve our ability to detect single cells in the retina over the current state-of-the-art AO retina cameras, including conventional flood illuminated and confocal scanning laser ophthalmoscopes. To our knowledge, this is the first effort to combine coherence gating and adaptive optics.

  12. Performance of laser guide star adaptive optics at Lick Observatory

    SciTech Connect

    Olivier, S.S.; An, J.; Avicola, K.

    1995-07-19

    A sodium-layer laser guide star adaptive optics system has been developed at Lawrence Livermore National Laboratory (LLNL) for use on the 3-meter Shane telescope at Lick Observatory. The system is based on a 127-actuator continuous-surface deformable mirror, a Hartmann wavefront sensor equipped with a fast-framing low-noise CCD camera, and a pulsed solid-state-pumped dye laser tuned to the atomic sodium resonance line at 589 nm. The adaptive optics system has been tested on the Shane telescope using natural reference stars yielding up to a factor of 12 increase in image peak intensity and a factor of 6.5 reduction in image full width at half maximum (FWHM). The results are consistent with theoretical expectations. The laser guide star system has been installed and operated on the Shane telescope yielding a beam with 22 W average power at 589 nm. Based on experimental data, this laser should generate an 8th magnitude guide star at this site, and the integrated laser guide star adaptive optics system should produce images with Strehl ratios of 0.4 at 2.2 {mu}m in median seeing and 0.7 at 2.2 {mu}m in good seeing.

  13. Real time optimization algorithm for wavefront sensorless adaptive optics OCT (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Verstraete, Hans R. G. W.; Heisler, Morgan; Ju, Myeong Jin; Wahl, Daniel J.; Bliek, Laurens; Kalkman, Jeroen; Bonora, Stefano; Sarunic, Marinko V.; Verhaegen, Michel; Jian, Yifan

    2017-02-01

    Optical Coherence Tomography (OCT) has revolutionized modern ophthalmology, providing depth resolved images of the retinal layers in a system that is suited to a clinical environment. A limitation of the performance and utilization of the OCT systems has been the lateral resolution. Through the combination of wavefront sensorless adaptive optics with dual variable optical elements, we present a compact lens based OCT system that is capable of imaging the photoreceptor mosaic. We utilized a commercially available variable focal length lens to correct for a wide range of defocus commonly found in patient eyes, and a multi-actuator adaptive lens after linearization of the hysteresis in the piezoelectric actuators for aberration correction to obtain near diffraction limited imaging at the retina. A parallel processing computational platform permitted real-time image acquisition and display. The Data-based Online Nonlinear Extremum seeker (DONE) algorithm was used for real time optimization of the wavefront sensorless adaptive optics OCT, and the performance was compared with a coordinate search algorithm. Cross sectional images of the retinal layers and en face images of the cone photoreceptor mosaic acquired in vivo from research volunteers before and after WSAO optimization are presented. Applying the DONE algorithm in vivo for wavefront sensorless AO-OCT demonstrates that the DONE algorithm succeeds in drastically improving the signal while achieving a computational time of 1 ms per iteration, making it applicable for high speed real time applications.

  14. The Role of Adaptive Photorefractive Power Limiting on Acousto-Optic Radio Frequency (RF) Signal Excision

    DTIC Science & Technology

    2001-12-01

    Adaptive RF interference reduction for broadband communication systems continues to be problematic. The acousto - optic RF signal excision system...novel photorefractive optical power limiting device to achieve adaptive notch filtering, and multi- channel acousto - optic deflection to achieve angle...of-arrival signal discrimination at the notch filter. This dissertation describes basic principles of acousto - optic RF signal excision, including

  15. Performance assessment of MEMS adaptive optics in tactical airborne systems

    NASA Astrophysics Data System (ADS)

    Tyson, Robert K.

    1999-09-01

    Tactical airborne electro-optical systems are severely constrained by weight, volume, power, and cost. Micro- electrical-mechanical adaptive optics provide a solution that addresses the engineering realities without compromising spatial and temporal compensation requirements. Through modeling and analysis, we determined that substantial benefits could be gained for laser designators, ladar, countermeasures, and missile seekers. The developments potential exists for improving seeker imagery resolution 20 percent, extending countermeasures keep-out range by a factor of 5, doubling the range for ladar detection and identification, and compensating for supersonic and hypersonic aircraft boundary layers. Innovative concepts are required for atmospheric pat hand boundary layer compensation. We have developed design that perform these tasks using high speed scene-based wavefront sensing, IR aerosol laser guide stars, and extended-object wavefront beacons. We have developed a number of adaptive optics system configurations that met the spatial resolution requirements and we have determined that sensing and signal processing requirements can be met. With the help of micromachined deformable mirrors and sensor, we will be able to integrate the systems into existing airborne pods and missiles as well as next generation electro-optical systems.

  16. Adaptive Optics Educational Outreach and the Giant Segmented Mirror Telescope

    NASA Astrophysics Data System (ADS)

    Sparks, R. T.; Pompea, S. M.; Walker, C. E.

    2008-06-01

    One of the limiting factors in telescope performance is atmospheric seeing. Atmospheric seeing limits the resolution of ground based optical telescopes. Even telescopes in good locations on top of mountains cannot achieve diffraction-limited resolution. Until recently, the only way to overcome this limitation was to use space-based telescopes. Adaptive Optics (AO) is a collection of technologies that measure the turbulence of Earth's atmosphere and compensate for the turbulence, resulting in high-resolution images without the expense and complexity of space based telescopes. Our Hands-On Optics program has developed activities that teach students how telescopes form images and make observations about the resolution of a telescope. We are developing materials for high school students to use in the study of adaptive optics. These activities include various ways to illustrate atmospheric distortion by using everyday materials such as bubble wrap and mineral oil. We will also illustrate how to demonstrate the workings of a Shack-Hartman sensor to measure atmospheric distortion through the use of a unique model. We will also show activities illustrating two techniques astronomers use to improve the image: tip-tilt mirrors and deformable mirrors. We are developing an activity where students learn how to use a tip-tilt mirror to keep an image focused at one point on a screen. The culminating activity has students learn to use a deformable mirror to correct a distorted wavefront. These activities are being developed in conjunction with the Education program for the Giant Segmented Mirror Telescope (GSMT).

  17. Lens-based wavefront sensorless adaptive optics swept source OCT

    NASA Astrophysics Data System (ADS)

    Jian, Yifan; Lee, Sujin; Ju, Myeong Jin; Heisler, Morgan; Ding, Weiguang; Zawadzki, Robert J.; Bonora, Stefano; Sarunic, Marinko V.

    2016-06-01

    Optical coherence tomography (OCT) has revolutionized modern ophthalmology, providing depth resolved images of the retinal layers in a system that is suited to a clinical environment. Although the axial resolution of OCT system, which is a function of the light source bandwidth, is sufficient to resolve retinal features at a micrometer scale, the lateral resolution is dependent on the delivery optics and is limited by ocular aberrations. Through the combination of wavefront sensorless adaptive optics and the use of dual deformable transmissive optical elements, we present a compact lens-based OCT system at an imaging wavelength of 1060 nm for high resolution retinal imaging. We utilized a commercially available variable focal length lens to correct for a wide range of defocus commonly found in patient’s eyes, and a novel multi-actuator adaptive lens for aberration correction to achieve near diffraction limited imaging performance at the retina. With a parallel processing computational platform, high resolution cross-sectional and en face retinal image acquisition and display was performed in real time. In order to demonstrate the system functionality and clinical utility, we present images of the photoreceptor cone mosaic and other retinal layers acquired in vivo from research subjects.

  18. Lens-based wavefront sensorless adaptive optics swept source OCT

    PubMed Central

    Jian, Yifan; Lee, Sujin; Ju, Myeong Jin; Heisler, Morgan; Ding, Weiguang; Zawadzki, Robert J.; Bonora, Stefano; Sarunic, Marinko V.

    2016-01-01

    Optical coherence tomography (OCT) has revolutionized modern ophthalmology, providing depth resolved images of the retinal layers in a system that is suited to a clinical environment. Although the axial resolution of OCT system, which is a function of the light source bandwidth, is sufficient to resolve retinal features at a micrometer scale, the lateral resolution is dependent on the delivery optics and is limited by ocular aberrations. Through the combination of wavefront sensorless adaptive optics and the use of dual deformable transmissive optical elements, we present a compact lens-based OCT system at an imaging wavelength of 1060 nm for high resolution retinal imaging. We utilized a commercially available variable focal length lens to correct for a wide range of defocus commonly found in patient’s eyes, and a novel multi-actuator adaptive lens for aberration correction to achieve near diffraction limited imaging performance at the retina. With a parallel processing computational platform, high resolution cross-sectional and en face retinal image acquisition and display was performed in real time. In order to demonstrate the system functionality and clinical utility, we present images of the photoreceptor cone mosaic and other retinal layers acquired in vivo from research subjects. PMID:27278853

  19. Forensic application of optical correction.

    PubMed

    Collins, Randall S; Berg, Gregory E

    2008-04-01

    Prescription eyewear can be used to aid in forensic investigations. Until now, investigators and consulted eye professionals have been limited to a simple "match" or "no match" judgment. This article introduces optometry to a Web-based tool that can be used to assess the strength of a match between spectacle prescriptions and recorded patient information. Three databases with more than 385,000 individual prescriptions were used to create the Web tool that calculates the frequency with which a prescription occurs in various U.S. populations. A search for any prescription in the tool's database will result in a report of the number of times a given prescription occurred in the queried database(s) as well as the calculated frequency with which the combination of the given sphere power, cylinder power and axis are likely to occur. Practical application of the Web tool in 2 published cases has shown matches with frequency of occurrence of 5.33 x 10(-6) and 2.66 x 10(-6), respectively. This application currently is being used by the Joint POW/MIA Accounting Command Central Identification Laboratory (JPAC-CIL) and other agencies when optical materials are available in forensic settings. Further, this application currently is contributing evidence in an active murder case. The creation of this easy-to-use Web tool allows eye care professionals to provide strong statistical assessments when serving as consultants to forensic investigators.

  20. A beam halo monitor based on adaptive optics

    NASA Astrophysics Data System (ADS)

    Welsch, C. P.; Bravin, E.; Lefèvre, T.

    2007-06-01

    In future high intensity, high energy accelerators, beam losses have to be minimized to maximize performance and reduce activation of accelerator components. It is imperative to have a clear understanding of the mechanisms that can lead to halo formation and to have the possibility to test available theoretical models with an adequate experimental setup. Measurements based on optical transition radiation (OTR) provide an interesting opportunity for high resolution measurements of the transverse beam profile. An imaging system based on a beam core-suppression technique, in which the core of the beam is deflected by means of a micro mirror array, to allow for direct observation of the halo has been developed. In this contribution, a possible layout of a novel diagnostic system based on adaptive optics is presented and the results of first tests carried out in our optical lab are summarized.

  1. Anisoplanatism in adaptive optics systems due to pupil aberrations

    SciTech Connect

    Bauman, B

    2005-08-01

    Adaptive optics systems typically include an optical relay that simultaneously images the science field to be corrected and also a set of pupil planes conjugate to the deformable mirror of the system. Often, in the optical spaces where DM's are placed, the pupils are aberrated, leading to a displacement and/or distortion of the pupil that varies according to field position--producing a type of anisoplanatism, i.e., a degradation of the AO correction with field angle. The pupil aberration phenomenon is described and expressed in terms of Seidel aberrations. An expression for anisoplanatism as a function of pupil distortion is derived, an example of an off-axis parabola is given, and a convenient method for controlling pupil-aberration-generated anisoplanatism is proposed.

  2. Adaptive-optics optical coherence tomography processing using a graphics processing unit.

    PubMed

    Shafer, Brandon A; Kriske, Jeffery E; Kocaoglu, Omer P; Turner, Timothy L; Liu, Zhuolin; Lee, John Jaehwan; Miller, Donald T

    2014-01-01

    Graphics processing units are increasingly being used for scientific computing for their powerful parallel processing abilities, and moderate price compared to super computers and computing grids. In this paper we have used a general purpose graphics processing unit to process adaptive-optics optical coherence tomography (AOOCT) images in real time. Increasing the processing speed of AOOCT is an essential step in moving the super high resolution technology closer to clinical viability.

  3. Adaptive-optics Optical Coherence Tomography Processing Using a Graphics Processing Unit*

    PubMed Central

    Shafer, Brandon A.; Kriske, Jeffery E.; Kocaoglu, Omer P.; Turner, Timothy L.; Liu, Zhuolin; Lee, John Jaehwan; Miller, Donald T.

    2015-01-01

    Graphics processing units are increasingly being used for scientific computing for their powerful parallel processing abilities, and moderate price compared to super computers and computing grids. In this paper we have used a general purpose graphics processing unit to process adaptive-optics optical coherence tomography (AOOCT) images in real time. Increasing the processing speed of AOOCT is an essential step in moving the super high resolution technology closer to clinical viability. PMID:25570838

  4. Optical properties of photoreceptor and retinal pigment epithelium cells investigated with adaptive optics optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Liu, Zhuolin

    Human vision starts when photoreceptors collect and respond to light. Photoreceptors do not function in isolation though, but share close interdependence with neighboring photoreceptors and underlying retinal pigment epithelium (RPE) cells. These cellular interactions are essential for normal function of the photoreceptor-RPE complex, but methods to assess these in the living human eye are limited. One approach that has gained increased promise is high-resolution retinal imaging that has undergone tremendous technological advances over the last two decades to probe the living retina at the cellular level. Pivotal in these advances has been adaptive optics (AO) and optical coherence tomography (OCT) that together allow unprecedented spatial resolution of retinal structures in all three dimensions. Using these high-resolution systems, cone photoreceptor are now routinely imaged in healthy and diseased retina enabling fundamental structural properties of cones to be studied such as cell spacing, packing arrangement, and alignment. Other important cell properties, however, have remained elusive to investigation as even better imaging performance is required and thus has resulted in an incomplete understanding of how cells in the photoreceptor-RPE complex interact with light. To address this technical bottleneck, we expanded the imaging capability of AO-OCT to detect and quantify more accurately and completely the optical properties of cone photoreceptor and RPE cells at the cellular level in the living human retina. The first objective of this thesis was development of a new AO-OCT method that is more precise and sensitive, thus enabling a more detailed view of the 3D optical signature of the photoreceptor-RPE complex than was previously possible (Chapter 2). Using this new system, the second objective was quantifying the waveguide properties of individual cone photoreceptor inner and outer segments across the macula (Chapter 3). The third objective extended the AO

  5. Siloxane materials for optical applications

    NASA Astrophysics Data System (ADS)

    Su, Kai; DeGroot, Jon V., Jr.; Norris, Ann W.; Lo, Peter Y.

    2006-01-01

    Siloxanes, which can be viewed as hybrids of glass and organic materials, have been used to fabricate polymer waveguides and devices that exploit the large thermo-optical effect of this material. Siloxanes have many unique properties including good thermal stability, chemical resistance, tunable refractive index, tunable mechanical properties and excellent photo-stability. The refractive index of siloxane polymer is composition dependent and generally ranges from 1.4 to 1.54. Introduction of porosity or composition modification can further expand refractive index range to 1.15~1.63. The loss and absorption characteristics for a variety of silicone-based polymers are examined and an example of a UV curable polymer coating illustrates the flexibility of the silicone polymer family to be tailored to meet specific application needs.

  6. Length-adaptive graph search for automatic segmentation of pathological features in optical coherence tomography images

    NASA Astrophysics Data System (ADS)

    Keller, Brenton; Cunefare, David; Grewal, Dilraj S.; Mahmoud, Tamer H.; Izatt, Joseph A.; Farsiu, Sina

    2016-07-01

    We introduce a metric in graph search and demonstrate its application for segmenting retinal optical coherence tomography (OCT) images of macular pathology. Our proposed "adjusted mean arc length" (AMAL) metric is an adaptation of the lowest mean arc length search technique for automated OCT segmentation. We compare this method to Dijkstra's shortest path algorithm, which we utilized previously in our popular graph theory and dynamic programming segmentation technique. As an illustrative example, we show that AMAL-based length-adaptive segmentation outperforms the shortest path in delineating the retina/vitreous boundary of patients with full-thickness macular holes when compared with expert manual grading.

  7. Applications of Neural Networks to Adaptive Control

    DTIC Science & Technology

    1989-12-01

    DTIC ;- E py 00 NAVAL POSTGRADUATE SCHOOL Monterey, California I.$ RDTIC IELECTE fl THESIS BEG7V°U APPLICATIONS OF NEURAL NETWORKS TO ADAPTIVE CONTROL...Second keader E . Robert Wood, Chairman, Department of Aeronautics and Astronautics Gordoii E . Schacher, Dean of Faculty and Graduate Education ii ABSTRACT...23: Network Dynamic Stability for q(t) . ............................. 55 ix Figure 24: Network Dynamic Stability for e (t

  8. Integrated modeling of the GMT laser tomography adaptive optics system

    NASA Astrophysics Data System (ADS)

    Piatrou, Piotr

    2014-08-01

    Laser Tomography Adaptive Optics (LTAO) is one of adaptive optics systems planned for the Giant Magellan Telescope (GMT). End-to-end simulation tools that are able to cope with the complexity and computational burden of the AO systems to be installed on the extremely large telescopes such as GMT prove to be an integral part of the GMT LTAO system development endeavors. SL95, the Fortran 95 Simulation Library, is one of the software tools successfully used for the LTAO system end-to-end simulations. The goal of SL95 project is to provide a complete set of generic, richly parameterized mathematical models for key elements of the segmented telescope wavefront control systems including both active and adaptive optics as well as the models for atmospheric turbulence, extended light sources like Laser Guide Stars (LGS), light propagation engines and closed-loop controllers. The library is implemented as a hierarchical collection of classes capable of mutual interaction, which allows one to assemble complex wavefront control system configurations with multiple interacting control channels. In this paper we demonstrate the SL95 capabilities by building an integrated end-to-end model of the GMT LTAO system with 7 control channels: LGS tomography with Adaptive Secondary and on-instrument deformable mirrors, tip-tilt and vibration control, LGS stabilization, LGS focus control, truth sensor-based dynamic noncommon path aberration rejection, pupil position control, SLODAR-like embedded turbulence profiler. The rich parameterization of the SL95 classes allows to build detailed error budgets propagating through the system multiple errors and perturbations such as turbulence-, telescope-, telescope misalignment-, segment phasing error-, non-common path-induced aberrations, sensor noises, deformable mirror-to-sensor mis-registration, vibration, temporal errors, etc. We will present a short description of the SL95 architecture, as well as the sample GMT LTAO system simulation

  9. Adaptive control of modal properties of optical beams using photothermal effects.

    PubMed

    Arain, Muzammil A; Korth, William Z; Williams, Luke F; Martin, Rodica M; Mueller, Guido; Tanner, D B; Reitze, David H

    2010-02-01

    We present an experimental demonstration of adaptive control of modal properties of optical beams. The control is achieved via heat-induced photothermal actuation of transmissive optical elements. We apply the heat using four electrical heaters in thermal contact with the element. The system is capable of controlling both symmetrical and astigmatic aberrations providing a powerful means for in situ correction and control of thermal aberrations in high power laser systems. We demonstrate a tunable lens with a focusing power varying from minus infinity to -10 m along two axes using SF57 optical glass. Applications of the proposed system include laser material processing, thermal compensation of high laser power radiation, and optical beam steering.

  10. The fundus photo has met its match: optical coherence tomography and adaptive optics ophthalmoscopy are here to stay

    PubMed Central

    Morgan, Jessica I. W.

    2016-01-01

    Purpose Over the past 25 years, optical coherence tomography (OCT) and adaptive optics (AO) ophthalmoscopy have revolutionised our ability to non-invasively observe the living retina. The purpose of this review is to highlight the techniques and human clinical applications of recent advances in OCT and adaptive optics scanning laser/light ophthalmoscopy (AOSLO) ophthalmic imaging. Recent findings Optical coherence tomography retinal and optic nerve head (ONH) imaging technology allows high resolution in the axial direction resulting in cross-sectional visualisation of retinal and ONH lamination. Complementary AO ophthalmoscopy gives high resolution in the transverse direction resulting in en face visualisation of retinal cell mosaics. Innovative detection schemes applied to OCT and AOSLO technologies (such as spectral domain OCT, OCT angiography, confocal and non-confocal AOSLO, fluorescence, and AO-OCT) have enabled high contrast between retinal and ONH structures in three dimensions and have allowed in vivo retinal imaging to approach that of histological quality. In addition, both OCT and AOSLO have shown the capability to detect retinal reflectance changes in response to visual stimuli, paving the way for future studies to investigate objective biomarkers of visual function at the cellular level. Increasingly, these imaging techniques are being applied to clinical studies of the normal and diseased visual system. Summary Optical coherence tomography and AOSLO technologies are capable of elucidating the structure and function of the retina and ONH noninvasively with unprecedented resolution and contrast. The techniques have proven their worth in both basic science and clinical applications and each will continue to be utilised in future studies for many years to come. PMID:27112222

  11. Adaptive optics at the Subaru telescope: current capabilities and development

    NASA Astrophysics Data System (ADS)

    Guyon, Olivier; Hayano, Yutaka; Tamura, Motohide; Kudo, Tomoyuki; Oya, Shin; Minowa, Yosuke; Lai, Olivier; Jovanovic, Nemanja; Takato, Naruhisa; Kasdin, Jeremy; Groff, Tyler; Hayashi, Masahiko; Arimoto, Nobuo; Takami, Hideki; Bradley, Colin; Sugai, Hajime; Perrin, Guy; Tuthill, Peter; Mazin, Ben

    2014-08-01

    Current AO observations rely heavily on the AO188 instrument, a 188-elements system that can operate in natural or laser guide star (LGS) mode, and delivers diffraction-limited images in near-IR. In its LGS mode, laser light is transported from the solid state laser to the launch telescope by a single mode fiber. AO188 can feed several instruments: the infrared camera and spectrograph (IRCS), a high contrast imaging instrument (HiCIAO) or an optical integral field spectrograph (Kyoto-3DII). Adaptive optics development in support of exoplanet observations has been and continues to be very active. The Subaru Coronagraphic Extreme-AO (SCExAO) system, which combines extreme-AO correction with advanced coronagraphy, is in the commissioning phase, and will greatly increase Subaru Telescope's ability to image and study exoplanets. SCExAO currently feeds light to HiCIAO, and will soon be combined with the CHARIS integral field spectrograph and the fast frame MKIDs exoplanet camera, which have both been specifically designed for high contrast imaging. SCExAO also feeds two visible-light single pupil interferometers: VAMPIRES and FIRST. In parallel to these direct imaging activities, a near-IR high precision spectrograph (IRD) is under development for observing exoplanets with the radial velocity technique. Wide-field adaptive optics techniques are also being pursued. The RAVEN multi-object adaptive optics instrument was installed on Subaru telescope in early 2014. Subaru Telescope is also planning wide field imaging with ground-layer AO with the ULTIMATE-Subaru project.

  12. High-resolution retinal imaging using adaptive optics and Fourier-domain optical coherence tomography

    DOEpatents

    Olivier, Scot S.; Werner, John S.; Zawadzki, Robert J.; Laut, Sophie P.; Jones, Steven M.

    2010-09-07

    This invention permits retinal images to be acquired at high speed and with unprecedented resolution in three dimensions (4.times.4.times.6 .mu.m). The instrument achieves high lateral resolution by using adaptive optics to correct optical aberrations of the human eye in real time. High axial resolution and high speed are made possible by the use of Fourier-domain optical coherence tomography. Using this system, we have demonstrated the ability to image microscopic blood vessels and the cone photoreceptor mosaic.

  13. Effectiveness of adaptive optics system in satellite-to-ground coherent optical communication.

    PubMed

    Jian, Huang; Ke, Deng; Chao, Liu; Peng, Zhang; Dagang, Jiang; Zhoushi, Yao

    2014-06-30

    Adaptive optics (AO) systems can suppress the signal fade induced by atmospheric turbulence in satellite-to-ground coherent optical communication. The lower bound of the signal fade under AO compensation was investigated by analyzing the pattern of aberration modes for a one-stage imaging AO system. The distribution of the root mean square of the residual aberration is discussed on the basis of the spatial and temporal characteristics of the residual aberration of the AO system. The effectiveness of the AO system for improving the performance of coherent optical communication is presented in terms of the bit error rate and system availability.

  14. Advanced Bonded Diamond for Optical Applications

    DTIC Science & Technology

    2011-11-28

    Final Report Contract # Number: Program Title: W911NF-07-2-0072 Advanced Bonded Diamond for Optical Applications Prime Contractor: Onyx Optics...Inc. 6551 Sierra Lane Dublin, Ca 94568 www.onyxoptics.com ONYXOpticsJnc. Program Manager: Helmuth Meissner Onyx Optics, Inc. 6551 Sierra Lane...structure Onyx Optics, Inc. Final Report for Contract # W911NF-07-2-0072 Based on the above observations, new designs have been suggested, whose pros

  15. Applications of fiber optics in physical protection

    SciTech Connect

    Buckle, T.H.

    1994-03-01

    The purpose of this NUREG is to provide technical information useful for the development of fiber-optic communications and intrusion detection subsystems relevant to physical protection. There are major sections on fiber-optic technology and applications. Other topics include fiber-optic system components and systems engineering. This document also contains a glossary, a list of standards and specifications, and a list of fiber-optic equipment vendors.

  16. Optical tweezers technique and its applications

    NASA Astrophysics Data System (ADS)

    Guo, HongLian; Li, ZhiYuan

    2013-12-01

    Since their advent in the 1980s, optical tweezers have attracted more and more attention due to their unique non-contact and non-invasion characteristics and their wide applications in physics, biology, chemistry, medical science and nanoscience. In this paper, we introduce the basic principle, the history and typical applications of optical tweezers and review our recent experimental works on the development and application of optical tweezers technique. We will discuss in detail several technological issues, including high precision displacement and force measurement in single-trap and dual-trap optical tweezers, multi-trap optical tweezers with each trap independently and freely controlled by means of space light modulator, and incorporation of cylindrical vector optical beams to build diversified optical tweezers beyond the conventional Gaussian-beam optical tweezers. We will address the application of these optical tweezers techniques to study biophysical problems such as mechanical deformation of cell membrane and binding energy between plant microtubule and microtubule associated proteins. Finally we present application of the optical tweezers technique for trapping, transporting, and patterning of metallic nanoparticles, which can be harnessed to manipulate surface plasmon resonance properties of these nanoparticles.

  17. Deformation of multilayers and optical surfaces in soft x-ray adaptive optics (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wylie-van Eerd, Benjamin J.; Yuan, Huiyu; Houwman, Evert; Antonov, Oleksandr; Louis, Eric; Yakshin, Andrey E.; Rijnders, Guus J. H. M.; Bijkerk, Fred

    2016-09-01

    Adaptive optics are of great utility in improving the resolving power of imaging and projection systems. In EUV lithography systems, for example, an adaptive optic can correct for wavefront deformation and decrease the feature size of integrated circuits that the system is in practice able to print. Piezoelectric thin films can be shown to accurately deform their surface with the sub-Angstrom precision required in order to compensate for wavefront deformation in EUV lithographic systems. However, in order to develop this from concept to working device, reflective coatings must be grown on top of the piezoelectric layer. Normal incidence EUV adaptive optics must meet the challenge of manipulating multilayer reflective coatings, while simultaneously preserving over many cycles the finely tuned structural properties that result in high XUV reflectivity. At this moment there are many unanswered questions in the literature about the behavior of an EUV multilayer under strain and the interaction of piezoelectric elements with multilayers. In this talk, we will present modelling of the response of multilayers to inhomogeneous strains that may be expected in a normal-incidence EUV adaptive optic, and preliminary experimental results.

  18. Fourier-Domain Optical Coherence Tomography and Adaptive Optics Reveal Nerve Fiber Layer Loss and Photoreceptor Changes in a Patient With Optic Nerve Drusen

    PubMed Central

    Choi, Stacey S.; Zawadzki, Robert J.; Greiner, Mark A.; Werner, John S.; Keltner, John L.

    2008-01-01

    Background New technology allows more precise definition of structural alterations of all retinal layers although it has not been used previously in cases of optic disc drusen. Methods Using Stratus and Fourier domain (FD) optical coherence tomography (OCT) and adaptive optics (AO) through a flood-illuminated fundus camera, we studied the retinas of a patient with long-standing optic disc drusen and acute visual loss at high altitude attributed to ischemic optic neuropathy. Results Stratus OCT and FD-OCT confirmed severe thinning of the retinal nerve fiber layer (RNFL). FD-OCT revealed disturbances in the photoreceptor layer heretofore not described in optic disc drusen patients. AO confirmed the FD-OCT findings in the photoreceptor layer and also showed reduced cone density at retinal locations associated with reduced visual sensitivity. Conclusions Based on this study, changes occur not only in the RNFL but also in the photoreceptor layer in optic nerve drusen complicated by ischemic optic neuropathy. This is the first reported application of FD-OCT and the AO to this condition. Such new imaging technology may in the future allow monitoring of disease progression more precisely and accurately. PMID:18562844

  19. Layer-oriented adaptive optics for solar telescopes.

    PubMed

    Kellerer, Aglaé

    2012-08-10

    First multiconjugate adaptive-optical (MCAO) systems are currently being installed on solar telescopes. The aim of these systems is to increase the corrected field of view with respect to conventional adaptive optics. However, this first generation is based on a star-oriented approach, and it is then difficult to increase the size of the field of view beyond 60-80 arc sec in diameter. We propose to implement the layer-oriented approach in solar MCAO systems by use of wide-field Shack-Hartmann wavefront sensors conjugated to the strongest turbulent layers. The wavefront distortions are averaged over a wide field: the signal from distant turbulence is attenuated and the tomographic reconstruction is thus done optically. The system consists of independent correction loops, which only need to account for local turbulence: the subapertures can be enlarged and the correction frequency reduced. Most importantly, a star-oriented MCAO system becomes more complex with increasing field size, while the layer-oriented approach benefits from larger fields and will therefore be an attractive solution for the future generation of solar MCAO systems.

  20. Superpenetration optical microscopy by iterative multiphoton adaptive compensation technique

    PubMed Central

    Tang, Jianyong; Germain, Ronald N.; Cui, Meng

    2012-01-01

    Biological tissues are rarely transparent, presenting major challenges for deep tissue optical microscopy. The achievable imaging depth is fundamentally limited by wavefront distortions caused by aberration and random scattering. Here, we report an iterative wavefront compensation technique that takes advantage of the nonlinearity of multiphoton signals to determine and compensate for these distortions and to focus light inside deep tissues. Different from conventional adaptive optics methods, this technique can rapidly measure highly complicated wavefront distortions encountered in deep tissue imaging and provide compensations for not only aberration but random scattering. The technique is tested with a variety of highly heterogeneous biological samples including mouse brain tissue, skull, and lymph nodes. We show that high quality three-dimensional imaging can be realized at depths beyond the reach of conventional multiphoton microscopy and adaptive optics methods, albeit over restricted distances for a given correction. Moreover, the required laser excitation power can be greatly reduced in deep tissues, deviating from the power requirement of ballistic light excitation and thus significantly reducing photo damage to the biological tissue. PMID:22586078

  1. Beam shaping for laser-based adaptive optics in astronomy.

    PubMed

    Béchet, Clémentine; Guesalaga, Andrés; Neichel, Benoit; Fesquet, Vincent; González-Núñez, Héctor; Zúñiga, Sebastián; Escarate, Pedro; Guzman, Dani

    2014-06-02

    The availability and performance of laser-based adaptive optics (AO) systems are strongly dependent on the power and quality of the laser beam before being projected to the sky. Frequent and time-consuming alignment procedures are usually required in the laser systems with free-space optics to optimize the beam. Despite these procedures, significant distortions of the laser beam have been observed during the first two years of operation of the Gemini South multi-conjugate adaptive optics system (GeMS). A beam shaping concept with two deformable mirrors is investigated in order to provide automated optimization of the laser quality for astronomical AO. This study aims at demonstrating the correction of quasi-static aberrations of the laser, in both amplitude and phase, testing a prototype of this two-deformable mirror concept on GeMS. The paper presents the results of the preparatory study before the experimental phase. An algorithm to control amplitude and phase correction, based on phase retrieval techniques, is presented with a novel unwrapping method. Its performance is assessed via numerical simulations, using aberrations measured at GeMS as reference. The results predict effective amplitude and phase correction of the laser distortions with about 120 actuators per mirror and a separation of 1.4 m between the mirrors. The spot size is estimated to be reduced by up to 15% thanks to the correction. In terms of AO noise level, this has the same benefit as increasing the photon flux by 40%.

  2. Adaptive Optics and Lucky Imager (AOLI): presentation and first light

    NASA Astrophysics Data System (ADS)

    Velasco, S.; Rebolo, R.; Mackay, C.; Oscoz, A.; King, D. L.; Crass, J.; Díaz-Sánchez, A.; Femenía, B.; González-Escalera, V.; Labadie, L.; López, R. L.; Pérez Garrido, A.; Puga, M.; Rodríguez-Ramos, L. F.; Zuther, J.

    2015-05-01

    In this paper we present the Adaptive Optics Lucky Imager (AOLI), a state-of-the-art instrument which makes use of two well proved techniques for extremely high spatial resolution with ground-based telescopes: Lucky Imaging (LI) and Adaptive Optics (AO). AOLI comprises an AO system, including a low order non-linear curvature wavefront sensor together with a 241 actuators deformable mirror, a science array of four 1024x1024 EMCCDs, allowing a 120×120 down to 36×36" field of view, a calibration subsystem and a powerful LI software. Thanks to the revolutionary WFS, AOLI shall have the capability of using faint reference stars (I˜16.5-17.5), enabling it to be used over a much wider part of the sky than with common Shack-Hartmann AO systems. This instrument saw first light in September 2013 at William Herschel Telescope. Although the instrument was not complete, these commissioning demonstrated its feasibility, obtaining a FWHM for the best PSF of 0.151±0.005" and a plate scale of 55.0±0.3 {mas} {pix}^{-1}. Those observations served us to prove some characteristics of the interesting multiple T Tauri system LkHα 262-263, finding it to be gravitationally bounded. This interesting multiple system mixes the presence of proto-planetary discs, one proved to be double, and the first-time optically resolved pair LkHα 263AB (0.42" separation).

  3. Initial Results from Implementing and Testing a MEMS Adaptive Optics System

    DTIC Science & Technology

    2009-07-01

    adaptive optics system using a Xinetics continuous face sheet deformable mirror with that of segmented MEMS deformable mirror. We intentionally...deformable mirror in adaptive optics. Here we present a comparison between a conventional adaptive optics system using a Xinetics continuous face sheet...DM as well as a Xinetics DM. 2.1 Optical set-up The ASALT lab uses an Atmospheric Turbulence Simulator (ATS) to simulate a two layer atmosphere with

  4. Adaptive optics optical coherence tomography for in vivo mouse retinal imaging

    PubMed Central

    Zawadzki, Robert J.; Sarunic, Marinko V.

    2013-01-01

    Abstract. Small animal models of retinal diseases are important to vision research, and noninvasive high resolution in vivo rodent retinal imaging is becoming an increasingly important tool used in this field. We present a custom Fourier domain optical coherence tomography (FD-OCT) instrument for high resolution imaging of mouse retina. In order to overcome aberrations in the mouse eye, we incorporated a commercial adaptive optics system into the sample arm of the refractive FD-OCT system. Additionally, a commercially available refraction canceling lens was used to reduce lower order aberrations and specular back-reflection from the cornea. Performance of the adaptive optics (AO) system for correcting residual wavefront aberration in the mice eyes is presented. Results of AO FD-OCT images of mouse retina acquired in vivo with and without AO correction are shown as well. PMID:23644903

  5. Parallel Programming Strategies for Irregular Adaptive Applications

    NASA Technical Reports Server (NTRS)

    Biswas, Rupak; Biegel, Bryan (Technical Monitor)

    2001-01-01

    Achieving scalable performance for dynamic irregular applications is eminently challenging. Traditional message-passing approaches have been making steady progress towards this goal; however, they suffer from complex implementation requirements. The use of a global address space greatly simplifies the programming task, but can degrade the performance for such computations. In this work, we examine two typical irregular adaptive applications, Dynamic Remeshing and N-Body, under competing programming methodologies and across various parallel architectures. The Dynamic Remeshing application simulates flow over an airfoil, and refines localized regions of the underlying unstructured mesh. The N-Body experiment models two neighboring Plummer galaxies that are about to undergo a merger. Both problems demonstrate dramatic changes in processor workloads and interprocessor communication with time; thus, dynamic load balancing is a required component.

  6. Data-based online nonlinear extremum-seeker for wavefront sensorless adaptive optics OCT (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Jian, Yifan; Verstraete, Hans R. G. W.; Heisler, Morgan; Ju, Myeong Jin; Wahl, Daniel J.; Bliek, Laurens; Kalkman, Jeroen; Bonora, Stefano; Verhaegen, Michel; Sarunic, Marinko V.

    2017-02-01

    Adaptive optics has been successfully applied to cellular resolution imaging of the retina, enabling visualization of the characteristic mosaic patterns of the outer retina. Wavefront sensorless adaptive optics (WSAO) is a novel technique that facilitates high resolution ophthalmic imaging; it replaces the Hartmann-Shack Wavefront Sensor with an image-driven optimization algorithm and mitigates some the challenges encountered with sensor-based designs. However, WSAO generally requires longer time to perform aberrations correction than the conventional closed-loop adaptive optics. When used for in vivo retinal imaging applications, motion artifacts during the WSAO optimization process will affect the quality of the aberration correction. A faster converging optimization scheme needs to be developed to account for rapid temporal variation of the wavefront and continuously apply corrections. In this project, we investigate the Databased Online Nonlinear Extremum-seeker (DONE), a novel non-linear multivariate optimization algorithm in combination with in vivo human WSAO OCT imaging. We also report both hardware and software updates of our compact lens based WSAO 1060nm swept source OCT human retinal imaging system, including real time retinal layer segmentation and tracking (ILM and RPE), hysteresis correction for the multi-actuator adaptive lens, precise synchronization control for the 200kHz laser source, and a zoom lens unit for rapid switching of the field of view. Cross sectional images of the retinal layers and en face images of the cone photoreceptor mosaic acquired in vivo from research volunteers before and after WSAO optimization are presented.

  7. Investigation on adaptive optics performance from propagation channel characterization with the small optical transponder

    NASA Astrophysics Data System (ADS)

    Petit, Cyril; Védrenne, Nicolas; Velluet, Marie Therese; Michau, Vincent; Artaud, Geraldine; Samain, Etienne; Toyoshima, Morio

    2016-11-01

    In order to address the high throughput requested for both downlink and uplink satellite to ground laser links, adaptive optics (AO) has become a key technology. While maturing, application of this technology for satellite to ground telecommunication, however, faces difficulties, such as higher bandwidth and optimal operation for a wide variety of atmospheric conditions (daytime and nighttime) with potentially low elevations that might severely affect wavefront sensing because of scintillation. To address these specificities, an accurate understanding of the origin of the perturbations is required, as well as operational validation of AO on real laser links. We report here on a low Earth orbiting (LEO) microsatellite to ground downlink with AO correction. We discuss propagation channel characterization based on Shack-Hartmann wavefront sensor (WFS) measurements. Fine modeling of the propagation channel is proposed based on multi-Gaussian model of turbulence profile. This model is then used to estimate the AO performance and validate the experimental results. While AO performance is limited by the experimental set-up, it proves to comply with expected performance and further interesting information on propagation channel is extracted. These results shall help dimensioning and operating AO systems for LEO to ground downlinks.

  8. Performance of keck adaptive optics with sodium laser guide star

    SciTech Connect

    Gavel, D.T.; Olivier, S.; Brase, J.

    1996-03-08

    The Keck telescope adaptive optics system is designed to optimize performance in he 1 to 3 micron region of observation wavelengths (J, H, and K astronomical bands). The system uses a 249 degree of freedom deformable mirror, so that the interactuator spacing is 56 cm as mapped onto the 10 meter aperture. 56 cm is roughly equal to r0 at 1.4 microns, which implies the wavefront fitting error is 0.52 ({lambda}/2{pi})({ital d}/{ital r}{sub 0}){sup 5/6} = 118 nm rms. This is sufficient to produce a system Strehl of 0.74 at 1.4 microns if all other sources of error are negligible, which would be the case with a bright natural guidestar and very high control bandwidth. Other errors associated with the adaptive optics will however contribute to Strehl degradation, namely, servo bandwidth error due to inability to reject all temporal frequencies of the aberrated wavefront, wavefront measurement error due to finite signal-to-noise ratio in the wavefront sensor, and, in the case of a laser guidestar, the so-called cone effect where rays from the guidestar beacon fail to sample some of the upper atmosphere turbulence. Cone effect is mitigated considerably by the use of the very high altitude sodium laser guidestar (90 km altitude), as opposed to Rayleigh beacons at 20 km. However, considering the Keck telescope`s large aperture, this is still the dominating wavefront error contributor in the current adaptive optics system design.

  9. OSCA, an optimised stellar coronagraph for adaptive optics

    NASA Astrophysics Data System (ADS)

    Thompson, Samantha Jayne

    Described here is the design, manufacturing, testing and commissioning of a coronagraph facility for the 4.2 metre William Herschel Telescope (WHT) and its adaptive optics system (NAOMI). The use of the NAOMI adaptive optics system gives an improved image resolution of ~ 0.15 arcseconds at a wavelength of 2.2?m. This enables the Optimised Stellar Coronagraph for Adaptive optics (OSCA) to null stellar light with smaller occulting masks and thus allows regions closer to bright astronomical objects to be imaged. OSCA is a fully deployable instrument which when in use leaves the focus of the NAOMI beam unchanged. This enables OSCA to be used in conjunction with a number of instruments that have already been commissioned at the WHT. The main imaging camera used with OSCA is INGRID; a 1024 x 1024 pixel HgCdTe cooled short-wave infra-red (SWIR) detector at the NAOMI focus. OSCA also has the option of being used in conjunction with an integral field spectrograph for imaging at visible wavelengths. OSCA provides a selection of 10 different occulting masks with sizes of 0.25 - 2.0 arcseconds in diameter, including two with novel gaussian profiles. There is also a choice of two different sized Lyot stops (pupil plane masks). A dichroic placed before the AO system can give improved suppression performance when occulting masks larger than the seeing disk are used. Also presented are results from observing time with the OSCA system, which highlight the challenges faced by astronomers to obtain high contrast, high resolution images from ground based telescopes. At a time during which there is much activity towards terrestrial planet finding, questions as to the system requirements required for such a task are discussed.

  10. Night Myopia Studied with an Adaptive Optics Visual Analyzer

    PubMed Central

    Artal, Pablo; Schwarz, Christina; Cánovas, Carmen; Mira-Agudelo, Alejandro

    2012-01-01

    Purpose Eyes with distant objects in focus in daylight are thought to become myopic in dim light. This phenomenon, often called “night myopia” has been studied extensively for several decades. However, despite its general acceptance, its magnitude and causes are still controversial. A series of experiments were performed to understand night myopia in greater detail. Methods We used an adaptive optics instrument operating in invisible infrared light to elucidate the actual magnitude of night myopia and its main causes. The experimental setup allowed the manipulation of the eye's aberrations (and particularly spherical aberration) as well as the use of monochromatic and polychromatic stimuli. Eight subjects with normal vision monocularly determined their best focus position subjectively for a Maltese cross stimulus at different levels of luminance, from the baseline condition of 20 cd/m2 to the lowest luminance of 22×10−6 cd/m2. While subjects performed the focusing tasks, their eye's defocus and aberrations were continuously measured with the 1050-nm Hartmann-Shack sensor incorporated in the adaptive optics instrument. The experiment was repeated for a variety of controlled conditions incorporating specific aberrations of the eye and chromatic content of the stimuli. Results We found large inter-subject variability and an average of −0.8 D myopic shift for low light conditions. The main cause responsible for night myopia was the accommodation shift occurring at low light levels. Other factors, traditionally suggested to explain night myopia, such as chromatic and spherical aberrations, have a much smaller effect in this mechanism. Conclusions An adaptive optics visual analyzer was applied to study the phenomenon of night myopia. We found that the defocus shift occurring in dim light is mainly due to accommodation errors. PMID:22768343

  11. Classical Optics and its Applications

    NASA Astrophysics Data System (ADS)

    Mansuripur, Masud

    2009-02-01

    Preface; Introduction; 1. Abbe's sine condition; 2. Fourier optics; 3. Effect of polarization on diffraction in systems of high numerical aperture; 4. Gaussian beam optics; 5. Coherent and incoherent imaging; 6. First-order temporal coherence in classical optics; 7. The Van Cittert-Zernike theorem; 8. Partial polarization, Stokes parameters, and the Poincarè Sphere; 9. Second-order coherence and the Hanbury Brown - Twiss experiment; 10. What in the world are surface plasmons?; 11. Surface plasmon polaritons on metallic surfaces; 12. The Faraday effecy; 13. The magneto-optical Kerr effect; 14. The Sagnac interferometer; 15. Fabry-Perot etalons in polarized light; 16. The Ewald-Oseen extinction theorem; 17. Reciprocity in classical Linear optics; 18. Optical pulse compression; 19. The uncertainty principle in classical optics; 20. Omni-directional dielectric mirrors; 21. Optical vortices; 22. Geometric-optical rays, Poynting's vector, and field momenta; 23. Doppler shift, stellar aberration, and convection of light by moving Media; 24. Diffraction gratings; 25. Diffractive optical elements; 26. The talbot effect; 27. Some quirks of total internal reflection; 28. Evanescent coupling; 29. Internal and external conical refraction; 30. Transmission of light through small elliptical apertures; 31. The method of Fox and Li; 32. The beam propagation method; 33. Launching light into a Fiber; 34. The optics of demiconductor fiode Laser; 35. Michelson's dtellar interferometer; 36. Bracewell's interferometric telescope; 37. Scanning optical microscopy; 38. Zernike's method of phase contrast; 39. Polarization microscopy; 40. Nomarski's differential interference contrast microscope; 41. The Van Leeuwenhoek microscope; 42. Projection photolithography; 43. Interaction of light with subwavelength structures; 44 The Ronchi test; 45. The Shack-Hartmann Wavefront sensor; 46. Ellipsometry; 47. Holography and holographic interferometry; 48. Self-focusing in non-linear optical media; 49

  12. Mechanics and applications of pressure adaptive honeycomb

    NASA Astrophysics Data System (ADS)

    Vos, Roelof

    A novel adaptive aerostructure is presented that relies on certified aerospace materials and can therefore be applied in conventional passenger aircraft. This structure consists of a honeycomb material which' cells extend over a significant length perpendicular to the plane of the cells. Each of the cells contains an inelastic pouch (or bladder) that forms a circular tube when the cell forms a perfect hexagon. By changing the cell differential pressure (CDP) the stiffness of the honeycomb can be altered. Using an external force or the elastic force within the honeycomb material, the honeycomb can be deformed such that the cells deviate from their perfect-hexagonal shape. It can be shown that by increasing the CDP, the structure eventually returns to a perfect hexagon. By doing so, a fully embedded pneumatic actuator is created that can perform work and substitute conventional low-bandwidth flight control actuators. It is shown that two approaches can be taken to regulate the stiffness of this embedded actuator: (1) The first approach relies on the pouches having a fixed amount of air in them and stiffness is altered by a change in ambient pressure. Coupled to the ambient pressure-altitude cycle that aircraft encounter during each flight, this approach yields a true adaptive aerostructure that operates independently of pilot input and is controlled solely by the altitude the aircraft is flying at. (2) The second approach relies on a controlled constant CDP. This CDP could be supplied from one of the compressor stages of the engine as a form of bleed air. Because of the air-tight pouches there would essentially be no mass flow, meaning engine efficiency would not be significantly affected due to this application. By means of a valve system the pilot could have direct control over the pressure and, consequently, the stiffness of the structure. This allows for much higher CDPs (on the order of 1MPa) than could physically be achieved by relying on the ambient pressure

  13. Adaptive spectral window sizes for feature extraction from optical spectra

    NASA Astrophysics Data System (ADS)

    Kan, Chih-Wen; Lee, Andy Y.; Pham, Nhi; Nieman, Linda T.; Sokolov, Konstantin; Markey, Mia K.

    2008-02-01

    We propose an approach to adaptively adjust the spectral window size used to extract features from optical spectra. Previous studies have employed spectral features extracted by dividing the spectra into several spectral windows of a fixed width. However, the choice of spectral window size was arbitrary. We hypothesize that by adaptively adjusting the spectral window sizes, the trends in the data will be captured more accurately. Our method was tested on a diffuse reflectance spectroscopy dataset obtained in a study of oblique polarization reflectance spectroscopy of oral mucosa lesions. The diagnostic task is to classify lesions into one of four histopathology groups: normal, benign, mild dysplasia, or severe dysplasia (including carcinoma). Nine features were extracted from each of the spectral windows. We computed the area (AUC) under Receiver Operating Characteristic curve to select the most discriminatory wavelength intervals. We performed pairwise classifications using Linear Discriminant Analysis (LDA) with leave-one-out cross validation. The results showed that for discriminating benign lesions from mild or severe dysplasia, the adaptive spectral window size features achieved AUC of 0.84, while a fixed spectral window size of 20 nm had AUC of 0.71, and an AUC of 0.64 is achieved with a large window size containing all wavelengths. The AUCs of all feature combinations were also calculated. These results suggest that the new adaptive spectral window size method effectively extracts features that enable accurate classification of oral mucosa lesions.

  14. Multiconjugate adaptive optics at the Vacuum Tower Telescope, Tenerife

    NASA Astrophysics Data System (ADS)

    Berkefeld, Thomas; Soltau, Dirk; von der Luehe, Oskar

    2002-02-01

    We present the optical setup and wavefront reconstruction algorithms for the multi-conjugate adaptive optics (MCAO) system at the 70 cm German Vacuum Tower Telescope (VTT), Observatorio del Teide, Tenerife. The system is designed to increase the corrected field of view (FOV) from about 10 arcseconds to 30 arcseconds in the visible. It will consist of two Shack-Hartmann wavefront sensors (WFS) and two deformable mirrors (DMs). Both wavefront sensors will be situated in the pupil plane of the telescope. One determines the high order wavefront aberrations for the center of the FOV, the other measures only low order wavefront aberrations, but covers a large FOV in each subaperture. A 35 actuator bimorph mirror and a micro mirror will correct the ground layer and the tropopause, respectively. The system will have first light in early 2002. Scientific operation is expected to start in the second half of 2002.

  15. Imaging of retinal vasculature using adaptive optics SLO/OCT.

    PubMed

    Felberer, Franz; Rechenmacher, Matthias; Haindl, Richard; Baumann, Bernhard; Hitzenberger, Christoph K; Pircher, Michael

    2015-04-01

    We use our previously developed adaptive optics (AO) scanning laser ophthalmoscope (SLO)/ optical coherence tomography (OCT) instrument to investigate its capability for imaging retinal vasculature. The system records SLO and OCT images simultaneously with a pixel to pixel correspondence which allows a direct comparison between those imaging modalities. Different field of views ranging from 0.8°x0.8° up to 4°x4° are supported by the instrument. In addition a dynamic focus scheme was developed for the AO-SLO/OCT system in order to maintain the high transverse resolution throughout imaging depth. The active axial eye tracking that is implemented in the OCT channel allows time resolved measurements of the retinal vasculature in the en-face imaging plane. Vessel walls and structures that we believe correspond to individual erythrocytes could be visualized with the system.

  16. Limits on Lyot coronagraphy with AEOS adaptive optics telescope

    NASA Astrophysics Data System (ADS)

    Sivaramakrishnan, A.; Makidon, R. B.; Lloyd, J. P.; Oppenheimer, B. R.; Graham, J. R.; Kalas, P. G.; Macintosh, B. A.; Max, C. E.; Baudoz, P.; Kuhn, J.; Potter, D.

    2001-05-01

    The 3.6m Air Force Electo-Optical System telescope is the most advanced adaptive optics (AO) system available to the astronomical community. Its 941-channel AO system feeds several stable instrument platforms at a very slow Cassegrain focus. Its small secondary obscuration makes it ideal for AO coronagraphy. We present estimates of current and theoretical limits on dynamic range using a diffraction-limited Lyot coronagraph optimized for the 3.6m AEOS telescope. We incorporate both the effects of imperfect AO correction of the wavefront and telescope guiding errors in our simulations. We calculate limits on faint companion detection (in the H-band) for this system at separations between 0.36 and 1.3 arcseconds.

  17. Aberrations and adaptive optics in super-resolution microscopy

    PubMed Central

    Booth, Martin; Andrade, Débora; Burke, Daniel; Patton, Brian; Zurauskas, Mantas

    2015-01-01

    As one of the most powerful tools in the biological investigation of cellular structures and dynamic processes, fluorescence microscopy has undergone extraordinary developments in the past decades. The advent of super-resolution techniques has enabled fluorescence microscopy – or rather nanoscopy – to achieve nanoscale resolution in living specimens and unravelled the interior of cells with unprecedented detail. The methods employed in this expanding field of microscopy, however, are especially prone to the detrimental effects of optical aberrations. In this review, we discuss how super-resolution microscopy techniques based upon single-molecule switching, stimulated emission depletion and structured illumination each suffer from aberrations in different ways that are dependent upon intrinsic technical aspects. We discuss the use of adaptive optics as an effective means to overcome this problem. PMID:26124194

  18. Optimization-based wavefront sensorless adaptive optics for multiphoton microscopy.

    PubMed

    Antonello, Jacopo; van Werkhoven, Tim; Verhaegen, Michel; Truong, Hoa H; Keller, Christoph U; Gerritsen, Hans C

    2014-06-01

    Optical aberrations have detrimental effects in multiphoton microscopy. These effects can be curtailed by implementing model-based wavefront sensorless adaptive optics, which only requires the addition of a wavefront shaping device, such as a deformable mirror (DM) to an existing microscope. The aberration correction is achieved by maximizing a suitable image quality metric. We implement a model-based aberration correction algorithm in a second-harmonic microscope. The tip, tilt, and defocus aberrations are removed from the basis functions used for the control of the DM, as these aberrations induce distortions in the acquired images. We compute the parameters of a quadratic polynomial that is used to model the image quality metric directly from experimental input-output measurements. Finally, we apply the aberration correction by maximizing the image quality metric using the least-squares estimate of the unknown aberration.

  19. Imaging of retinal vasculature using adaptive optics SLO/OCT

    PubMed Central

    Felberer, Franz; Rechenmacher, Matthias; Haindl, Richard; Baumann, Bernhard; Hitzenberger, Christoph K.; Pircher, Michael

    2015-01-01

    We use our previously developed adaptive optics (AO) scanning laser ophthalmoscope (SLO)/ optical coherence tomography (OCT) instrument to investigate its capability for imaging retinal vasculature. The system records SLO and OCT images simultaneously with a pixel to pixel correspondence which allows a direct comparison between those imaging modalities. Different field of views ranging from 0.8°x0.8° up to 4°x4° are supported by the instrument. In addition a dynamic focus scheme was developed for the AO-SLO/OCT system in order to maintain the high transverse resolution throughout imaging depth. The active axial eye tracking that is implemented in the OCT channel allows time resolved measurements of the retinal vasculature in the en-face imaging plane. Vessel walls and structures that we believe correspond to individual erythrocytes could be visualized with the system. PMID:25909024

  20. Aberrations and adaptive optics in super-resolution microscopy.

    PubMed

    Booth, Martin; Andrade, Débora; Burke, Daniel; Patton, Brian; Zurauskas, Mantas

    2015-08-01

    As one of the most powerful tools in the biological investigation of cellular structures and dynamic processes, fluorescence microscopy has undergone extraordinary developments in the past decades. The advent of super-resolution techniques has enabled fluorescence microscopy - or rather nanoscopy - to achieve nanoscale resolution in living specimens and unravelled the interior of cells with unprecedented detail. The methods employed in this expanding field of microscopy, however, are especially prone to the detrimental effects of optical aberrations. In this review, we discuss how super-resolution microscopy techniques based upon single-molecule switching, stimulated emission depletion and structured illumination each suffer from aberrations in different ways that are dependent upon intrinsic technical aspects. We discuss the use of adaptive optics as an effective means to overcome this problem.

  1. Six-channel adaptive fibre-optic interferometer

    SciTech Connect

    Romashko, R V; Bezruk, M N; Kamshilin, A A; Kulchin, Yurii N

    2012-06-30

    We have proposed and analysed a scheme for the multiplexing of orthogonal dynamic holograms in photorefractive crystals which ensures almost zero cross talk between the holographic channels upon phase demodulation. A six-channel adaptive fibre-optic interferometer was built, and the detection limit for small phase fluctuations in the channels of the interferometer was determined to be 2.1 Multiplication-Sign 10{sup -8} rad W{sup 1/2} Hz{sup -1/2}. The channel multiplexing capacity of the interferometer was estimated. The formation of 70 channels such that their optical fields completely overlap in the crystal reduces the relative detection limit in the working channel by just 10 %. We found conditions under which the maximum cross talk between the channels was within the intrinsic noise level in the channels (-47 dB).

  2. Adaptive optics retinal scanner for one-micrometer light source.

    PubMed

    Kurokawa, Kazuhiro; Tamada, Daiki; Makita, Shuichi; Yasuno, Yoshiaki

    2010-01-18

    We developed an adaptive optics (AO) retinal scanner by using a light source with a center wavelength of 1-microm. In a recent study on optical coherence tomography (OCT), it was proved that 1-microm light provided higher image contrast of deep region of the eye than 840-nm light. Further, high lateral resolution retinal images were obtained with AO. In this study, we performed measurements on two normal subjects in the AO-SLO mode and analyzed its performance toward developing the AO-OCT. With AO correction, we found that the residual RMS wavefront error of ocular aberration was less than 0.1 microm. We also found that the AO retinal scanner in the AO-SLO mode enabled enhanced observation of photoreceptor mosaic.

  3. Adaptive optical two-photon microscopy using autofluorescent guide stars.

    PubMed

    Tao, Xiaodong; Norton, Andrew; Kissel, Matthew; Azucena, Oscar; Kubby, Joel

    2013-12-01

    We demonstrate a fast, direct wavefront-sensing method for dynamic in vivo adaptive optical two-photon microscopy. By using a Shack-Hartmann wavefront sensor and open-loop control, the system provides high-speed wavefront measurement and correction. To measure the wavefront in the middle of a Drosophila embryo at early stages, autofluorescence from endogenous fluorophores in the yolk were used as reference guide stars. The method was tested through live imaging of a Drosophila embryo. The aberration in the middle of the embryo was measured directly for the first time. After correction, the contrast and signal intensity of the structure in the middle of the embryo was improved.

  4. Performance predictions for the Keck telescope adaptive optics system

    SciTech Connect

    Gavel, D.T.; Olivier, S.S.

    1995-08-07

    The second Keck ten meter telescope (Keck-11) is slated to have an infrared-optimized adaptive optics system in the 1997--1998 time frame. This system will provide diffraction-limited images in the 1--3 micron region and the ability to use a diffraction-limited spectroscopy slit. The AO system is currently in the preliminary design phase and considerable analysis has been performed in order to predict its performance under various seeing conditions. In particular we have investigated the point-spread function, energy through a spectroscopy slit, crowded field contrast, object limiting magnitude, field of view, and sky coverage with natural and laser guide stars.

  5. Artificial testing targets with controllable blur for adaptive optics microscopes

    NASA Astrophysics Data System (ADS)

    Hattori, Masayuki; Tamada, Yosuke; Murata, Takashi; Oya, Shin; Hasebe, Mitsuyasu; Hayano, Yutaka; Kamei, Yasuhiro

    2017-08-01

    This letter proposes a method of configuring a testing target to evaluate the performance of adaptive optics microscopes. In this method, a testing slide with fluorescent beads is used to simultaneously determine the point spread function and the field of view. The point spread function is reproduced to simulate actual biological samples by etching a microstructure on the cover glass. The fabrication process is simplified to facilitate an onsite preparation. The artificial tissue consists of solid materials and silicone oil and is stable for use in repetitive experiments.

  6. Performance of the Gemini Planet Imager's adaptive optics system.

    PubMed

    Poyneer, Lisa A; Palmer, David W; Macintosh, Bruce; Savransky, Dmitry; Sadakuni, Naru; Thomas, Sandrine; Véran, Jean-Pierre; Follette, Katherine B; Greenbaum, Alexandra Z; Ammons, S Mark; Bailey, Vanessa P; Bauman, Brian; Cardwell, Andrew; Dillon, Daren; Gavel, Donald; Hartung, Markus; Hibon, Pascale; Perrin, Marshall D; Rantakyrö, Fredrik T; Sivaramakrishnan, Anand; Wang, Jason J

    2016-01-10

    The Gemini Planet Imager's adaptive optics (AO) subsystem was designed specifically to facilitate high-contrast imaging. A definitive description of the system's algorithms and technologies as built is given. 564 AO telemetry measurements from the Gemini Planet Imager Exoplanet Survey campaign are analyzed. The modal gain optimizer tracks changes in atmospheric conditions. Science observations show that image quality can be improved with the use of both the spatially filtered wavefront sensor and linear-quadratic-Gaussian control of vibration. The error budget indicates that for all targets and atmospheric conditions AO bandwidth error is the largest term.

  7. Reconfigurable surface plasmon polariton wave adapter designed by transformation optics.

    PubMed

    Arigong, Bayaner; Shao, Jin; Ren, Han; Zheng, Geng; Lutkenhaus, Jeffrey; Kim, HyoungSoo; Lin, Yuankun; Zhang, Hualiang

    2012-06-18

    In this paper, we propose a reconfigurable surface plasmon polariton (SPP) wave adapter designed by transformation optics, which can control the propagation of SPP waves on un-even surfaces. The proposed plasmonic device is constructed using homogeneously tunable materials (e.g. liquid crystals) so that the corresponding SPP wave transmission can be reconfigured by applying different voltages. Additionally, modified designs optimized for practical fabrication parameters are investigated. Their performance is verified by full-wave simulations. The proposed devices will pave the way towards developing tunable plasmonic devices.

  8. Closed-Loop Adaptive Optics Control in Strong Atmospheric Turbulence

    DTIC Science & Technology

    2008-09-01

    Atmospheric Turbulence Todd M. Venema, B.S.E., M.S.E.E. Lieutenant Colonel, USAF Approved: Dr. Juan Vasquez , (Chairman) Date Maj. Jason Schmidt, PhD (Member...to acknowledge the help of Jason Schmidt and Juan Vasquez , my Air Force Institute of Technology advisors. I would also like to acknowledge the help of...Darryl Sanchez and Denis Oesch from the Air Force’s Starfire Optical Range in helping me study my designs in their Atmospheric Simulation and Adaptive

  9. Precision Targeting with a Tracking adaptive Optics Scanning Laser Ophthalmoscope

    DTIC Science & Technology

    2006-02-01

    in Figure 2) but drives two galvanometers placed at appropriate conjugates within the path of the adaptive optics scanning laser ophthalmoscope...reflectometer. The input to the "slave" control loop is the scaled position signals from the master galvanometers . The slave tracking mirrors are placed at...signals and drive galvanometers . The DSP has a loop rate of 62.5 kHz (compared to 16 kHz in the previously-used real-time processing board) for a

  10. Deformable mirrors for open-loop adaptive optics

    NASA Astrophysics Data System (ADS)

    Kellerer, A.; Vidal, F.; Gendron, E.; Hubert, Z.; Perret, D.; Rousset, G.

    2012-07-01

    We characterize the performance of deformable mirrors for use in open-loop regimes. This is especially relevant for Multi Object Adaptive Optics (MOAO), or for closed-loop schemes that require improved accuracies. Deformable mirrors are usually characterized by standard parameters, such as influence functions, linearity, hysteresis, etc. We show that these parameters are insufficient for characterizing open-loop performance and that a deeper analysis of the mirror's behavior is then required. The measurements on the deformable mirrors were performed in 2007 on the AO test bench of the Meudon observatory, SESAME.

  11. Self-characterization of linear and nonlinear adaptive optics systems

    NASA Astrophysics Data System (ADS)

    Hampton, Peter J.; Conan, Rodolphe; Keskin, Onur; Bradley, Colin; Agathoklis, Pan

    2008-01-01

    We present methods used to determine the linear or nonlinear static response and the linear dynamic response of an adaptive optics (AO) system. This AO system consists of a nonlinear microelectromechanical systems deformable mirror (DM), a linear tip-tilt mirror (TTM), a control computer, and a Shack-Hartmann wavefront sensor. The system is modeled using a single-input-single-output structure to determine the one-dimensional transfer function of the dynamic response of the chain of system hardware. An AO system has been shown to be able to characterize its own response without additional instrumentation. Experimentally determined models are given for a TTM and a DM.

  12. An adaptive optics imaging system designed for clinical use

    PubMed Central

    Zhang, Jie; Yang, Qiang; Saito, Kenichi; Nozato, Koji; Williams, David R.; Rossi, Ethan A.

    2015-01-01

    Here we demonstrate a new imaging system that addresses several major problems limiting the clinical utility of conventional adaptive optics scanning light ophthalmoscopy (AOSLO), including its small field of view (FOV), reliance on patient fixation for targeting imaging, and substantial post-processing time. We previously showed an efficient image based eye tracking method for real-time optical stabilization and image registration in AOSLO. However, in patients with poor fixation, eye motion causes the FOV to drift substantially, causing this approach to fail. We solve that problem here by tracking eye motion at multiple spatial scales simultaneously by optically and electronically integrating a wide FOV SLO (WFSLO) with an AOSLO. This multi-scale approach, implemented with fast tip/tilt mirrors, has a large stabilization range of ± 5.6°. Our method consists of three stages implemented in parallel: 1) coarse optical stabilization driven by a WFSLO image, 2) fine optical stabilization driven by an AOSLO image, and 3) sub-pixel digital registration of the AOSLO image. We evaluated system performance in normal eyes and diseased eyes with poor fixation. Residual image motion with incremental compensation after each stage was: 1) ~2–3 arc minutes, (arcmin) 2) ~0.5–0.8 arcmin and, 3) ~0.05–0.07 arcmin, for normal eyes. Performance in eyes with poor fixation was: 1) ~3–5 arcmin, 2) ~0.7–1.1 arcmin and 3) ~0.07–0.14 arcmin. We demonstrate that this system is capable of reducing image motion by a factor of ~400, on average. This new optical design provides additional benefits for clinical imaging, including a steering subsystem for AOSLO that can be guided by the WFSLO to target specific regions of interest such as retinal pathology and real-time averaging of registered images to eliminate image post-processing. PMID:26114033

  13. An adaptive optics imaging system designed for clinical use.

    PubMed

    Zhang, Jie; Yang, Qiang; Saito, Kenichi; Nozato, Koji; Williams, David R; Rossi, Ethan A

    2015-06-01

    Here we demonstrate a new imaging system that addresses several major problems limiting the clinical utility of conventional adaptive optics scanning light ophthalmoscopy (AOSLO), including its small field of view (FOV), reliance on patient fixation for targeting imaging, and substantial post-processing time. We previously showed an efficient image based eye tracking method for real-time optical stabilization and image registration in AOSLO. However, in patients with poor fixation, eye motion causes the FOV to drift substantially, causing this approach to fail. We solve that problem here by tracking eye motion at multiple spatial scales simultaneously by optically and electronically integrating a wide FOV SLO (WFSLO) with an AOSLO. This multi-scale approach, implemented with fast tip/tilt mirrors, has a large stabilization range of ± 5.6°. Our method consists of three stages implemented in parallel: 1) coarse optical stabilization driven by a WFSLO image, 2) fine optical stabilization driven by an AOSLO image, and 3) sub-pixel digital registration of the AOSLO image. We evaluated system performance in normal eyes and diseased eyes with poor fixation. Residual image motion with incremental compensation after each stage was: 1) ~2-3 arc minutes, (arcmin) 2) ~0.5-0.8 arcmin and, 3) ~0.05-0.07 arcmin, for normal eyes. Performance in eyes with poor fixation was: 1) ~3-5 arcmin, 2) ~0.7-1.1 arcmin and 3) ~0.07-0.14 arcmin. We demonstrate that this system is capable of reducing image motion by a factor of ~400, on average. This new optical design provides additional benefits for clinical imaging, including a steering subsystem for AOSLO that can be guided by the WFSLO to target specific regions of interest such as retinal pathology and real-time averaging of registered images to eliminate image post-processing.

  14. Three-dimensional focusing through scattering media using conjugate adaptive optics with remote focusing (CAORF).

    PubMed

    Tao, Xiaodong; Lam, Tuwin; Zhu, Bingzhao; Li, Qinggele; Reinig, Marc R; Kubby, Joel

    2017-05-01

    The small correction volume for conventional wavefront shaping methods limits their application in biological imaging through scattering media. We demonstrate large volume wavefront shaping through a scattering layer with a single correction by conjugate adaptive optics and remote focusing (CAORF). The remote focusing module can maintain the conjugation between the adaptive optical (AO) element and the scattering layer during three-dimensional scanning. This new configuration provides a wider correction volume by better utilization of the memory effect in a fast three-dimensional laser scanning microscope. Our results show that the proposed system can provide 10 times wider axial field of view compared with a conventional conjugate AO system when 16,384 segments are used on a spatial light modulator. We also demonstrate three-dimensional fluorescence imaging, multi-spot patterning through a scattering layer and two-photon imaging through mouse skull tissue.

  15. Perceptual image quality in normalized LOG domain for Adaptive Optics image post-processing

    NASA Astrophysics Data System (ADS)

    Guo, Shiping; Zhang, Rongzhi; Li, Jisheng; Zou, Jianhua; Liu, Changhai; Gao, Weizhe

    2015-08-01

    Adaptive Optics together with subsequent post-processing techniques obviously improve the resolution of turbulencedegraded images in ground-based space objects detection and identification. The most common method for frame selection and stopping iteration in post-processing has always been subjective viewing of the images due to a lack of widely agreed-upon objective quality metric. Full reference metrics are not applicable for assessing the field data, no-reference metrics tend to perform poor sensitivity for Adaptive Optics images. In the present work, based on the Laplacian of Gaussian (LOG) local contrast feature, a nonlinear normalization is applied to transform the input image into a normalized LOG domain; a quantitative index is then extracted in this domain to assess the perceptual image quality. Experiments show this no-reference quality index is highly consistent with the subjective evaluation of input images for different blur degree and different iteration number.

  16. On distributed wavefront reconstruction for large-scale adaptive optics systems.

    PubMed

    de Visser, Cornelis C; Brunner, Elisabeth; Verhaegen, Michel

    2016-05-01

    The distributed-spline-based aberration reconstruction (D-SABRE) method is proposed for distributed wavefront reconstruction with applications to large-scale adaptive optics systems. D-SABRE decomposes the wavefront sensor domain into any number of partitions and solves a local wavefront reconstruction problem on each partition using multivariate splines. D-SABRE accuracy is within 1% of a global approach with a speedup that scales quadratically with the number of partitions. The D-SABRE is compared to the distributed cumulative reconstruction (CuRe-D) method in open-loop and closed-loop simulations using the YAO adaptive optics simulation tool. D-SABRE accuracy exceeds CuRe-D for low levels of decomposition, and D-SABRE proved to be more robust to variations in the loop gain.

  17. Phase aberration correction by correlation in digital holographic adaptive optics

    PubMed Central

    Liu, Changgeng; Yu, Xiao; Kim, Myung K.

    2013-01-01

    We present a phase aberration correction method based on the correlation between the complex full-field and guide-star holograms in the context of digital holographic adaptive optics (DHAO). Removal of a global quadratic phase term before the correlation operation plays an important role in the correction. Correlation operation can remove the phase aberration at the entrance pupil plane and automatically refocus the corrected optical field. Except for the assumption that most aberrations lie at or close to the entrance pupil, the presented method does not impose any other constraints on the optical systems. Thus, it greatly enhances the flexibility of the optical design for DHAO systems in vision science and microscopy. Theoretical studies show that the previously proposed Fourier transform DHAO (FTDHAO) is just a special case of this general correction method, where the global quadratic phase term and a defocus term disappear. Hence, this correction method realizes the generalization of FTDHAO into arbitrary DHAO systems. The effectiveness and robustness of this method are demonstrated by simulations and experiments. PMID:23669707

  18. Diffractive pyramid wave-front sensor used for adaptive optics

    NASA Astrophysics Data System (ADS)

    Zhao, Yuan; Ding, Xiaona; Wang, Kun; Wei, Hongyan; Yang, Huan; Cai, Dongmei

    2012-10-01

    Wave-front sensor, as the main component of Adaptive optics system, detects light from the astronomic object or reference sources. It aims to improve the utilization of light, especially for AO system work with the faint objects. Compared with Shack-Hartmann sensor, pyramid wave-front sensor is a relatively new one with increased pupil sampling and spatial resolution. Pyramid wave-front sensor uses a refractive element (the pyramid) to produce four images of the entrance pupil. Usually, Single pyramid prototypes are made using the classical figuring and polishing techniques. This approach, however, is not only very time consuming but also does not guarantee a uniform repeatability of the optical characteristics of the pyramids. The loss of low frequency component increases due to the roofs existing on its vertexes. Moreover, stray light is introduced in the four images. We therefore are investigating a modified pyramidal optical components based on the binary optical concept. In this article we describe the diffractive pyramid prototypes using the micro fabrication technique. The parameters of the pyramid are discussed.

  19. Transparent Optical Protection Ring Architectures and Applications

    NASA Astrophysics Data System (ADS)

    Li, Ming-Jun; Soulliere, Mark J.; Tebben, Daniel J.; Nederlof, Leo; Vaughn, Mark D.; Wagner, Richard E.

    2005-10-01

    This paper reviews recent progress in optical protection rings with the focus on transparent optical protection rings. Different optical protection ring architectures, such as dedicated and shared protection rings, in both the optical-channel (OCh) layer and the optical multiplex section (OMS) layer, are described. In particular, OCh shared protection rings (OChSPRINGs) are discussed in detail including node-architecture designs, ring protocols, triggers, and messaging channels. Feasibility studies and experimental results from Corning Inc. and other companies are reviewed. The paper also discusses how protection-switching times scale with number of nodes and number of wavelengths, and shows examples of applications using the scaling rules for practical optical networks such as metro, regional, and long-haul ring networks. The cost benefits of transparent optical protection rings are analyzed using a typical metro network. Finally, the paper discusses remaining issues and future developments in the optical protection ring area.

  20. Harnessing Adaptive Optics for Space Debris Collision Mitigation

    NASA Astrophysics Data System (ADS)

    Zovaro, A.; Bennet, F.; Copeland, M.; Rigaut, F.; d'Orgeville, C.; Grosse, D.

    2016-09-01

    Human kind's continued use of space depends upon minimising the build-up of debris in low Earth-orbit (LEO). Preventing collisions between satellites and debris is essential given that a single collision can generate thousands of new debris objects. However, in-orbit manoeuvring of satellites is extremely expensive and shortens their operational life. Adjusting the orbits of debris objects instead of satellites would shift the responsibility of collision avoidance away from satellite operators altogether, thereby offering a superior solution. The Research School of Astronomy and Astrophysics at the Australian National University, partnered with Electro Optic Systems (EOS) Space Systems, Lockheed Martin Corporation and the Space Environment Research Centre (SERC) Limited, are developing the Adaptive Optics Tracking and Pushing (AOTP) system. AOTP will be used to perturb the orbits of debris objects using photon pressure from a 10 kW IR laser beam launched from the 1.8 m telescope at Mount. Stromlo Observatory, Australia. Initial simulations predict that AOTP will be able to displace debris objects 10 cm in size by up to 100 m with several overhead passes. An operational demonstrator is planned for 2019. Turbulence will distort the laser beam as it propagates through the atmosphere, resulting in a lower photon flux on the target and reduced pointing accuracy. To mitigate these effects, adaptive optics (AO) will be used to apply wavefront correction to the beam prior to launch. A unique challenge in designing the AO system arises from the high slew rate needed to track objects in LEO, which in turn requires laser guide star AO for satisfactory wavefront correction. The optical design and results from simulations of estimated performance of AOTP will be presented. In particular, design considerations associated with the high-power laser will be detailed.

  1. Design of the Dual Conjugate Adaptive Optics Test-bed

    NASA Astrophysics Data System (ADS)

    Sharf, Inna; Bell, K.; Crampton, D.; Fitzsimmons, J.; Herriot, Glen; Jolissaint, Laurent; Lee, B.; Richardson, H.; van der Kamp, D.; Veran, Jean-Pierre

    In this paper, we describe the Multi-Conjugate Adaptive Optics laboratory test-bed presently under construction at the University of Victoria, Canada. The test-bench will be used to support research in the performance of multi-conjugate adaptive optics, turbulence simulators, laser guide stars and miniaturizing adaptive optics. The main components of the test-bed include two micro-machined deformable mirrors, a tip-tilt mirror, four wavefront sensors, a source simulator, a dual-layer turbulence simulator, as well as computational and control hardware. The paper will describe in detail the opto-mechanical design of the adaptive optics module, the design of the hot-air turbulence generator and the configuration chosen for the source simulator. Below, we present a summary of these aspects of the bench. The optical and mechanical design of the test-bed has been largely driven by the particular choice of the deformable mirrors. These are continuous micro-machined mirrors manufactured by Boston Micromachines Corporation. They have a clear aperture of 3.3 mm and are deformed with 140 actuators arranged in a square grid. Although the mirrors have an open-loop bandwidth of 6.6 KHz, their shape can be updated at a sampling rate of 100 Hz. In our optical design, the mirrors are conjugated at 0km and 10 km in the atmosphere. A planar optical layout was achieved by using four off-axis paraboloids and several folding mirrors. These optics will be mounted on two solid blocks which can be aligned with respect to each other. The wavefront path design accommodates 3 monochromatic guide stars that can be placed at either 90 km or at infinity. The design relies on the natural separation of the beam into 3 parts because of differences in locations of the guide stars in the field of view. In total four wavefront sensors will be procured from Adaptive Optics Associates (AOA) or built in-house: three for the guide stars and the fourth to collect data from the science source output in

  2. Adaptive multidimensional modulation and multiplexing for next generation optical networks

    NASA Astrophysics Data System (ADS)

    Cvijetic, Milorad

    2015-01-01

    The overall spectral efficiency in optical transmission systems needs to be enhanced by employment of advanced modulation, multiplexing, and coding schemes, as well as the advanced detection techniques. In parallel, novel networking concepts with the griddles and elastic bandwidth allocation are needed to increase the network dynamics and flexibility. In this paper we discuss multidimensional modulation, multiplexing, and coding schemes, which are enablers not only of the information capacity increase, but also for the next generation elastic high-speed optical networking and outline possible future directions and application scenario in different networking segments.

  3. Adaptive coded aperture imaging: progress and potential future applications

    NASA Astrophysics Data System (ADS)

    Gottesman, Stephen R.; Isser, Abraham; Gigioli, George W., Jr.

    2011-09-01

    Interest in Adaptive Coded Aperture Imaging (ACAI) continues to grow as the optical and systems engineering community becomes increasingly aware of ACAI's potential benefits in the design and performance of both imaging and non-imaging systems , such as good angular resolution (IFOV), wide distortion-free field of view (FOV), excellent image quality, and light weight construct. In this presentation we first review the accomplishments made over the past five years, then expand on previously published work to show how replacement of conventional imaging optics with coded apertures can lead to a reduction in system size and weight. We also present a trade space analysis of key design parameters of coded apertures and review potential applications as replacement for traditional imaging optics. Results will be presented, based on last year's work of our investigation into the trade space of IFOV, resolution, effective focal length, and wavelength of incident radiation for coded aperture architectures. Finally we discuss the potential application of coded apertures for replacing objective lenses of night vision goggles (NVGs).

  4. In vivo imaging of human photoreceptor mosaic with wavefront sensorless adaptive optics optical coherence tomography

    PubMed Central

    Wong, Kevin S. K.; Jian, Yifan; Cua, Michelle; Bonora, Stefano; Zawadzki, Robert J.; Sarunic, Marinko V.

    2015-01-01

    Wavefront sensorless adaptive optics optical coherence tomography (WSAO-OCT) is a novel imaging technique for in vivo high-resolution depth-resolved imaging that mitigates some of the challenges encountered with the use of sensor-based adaptive optics designs. This technique replaces the Hartmann Shack wavefront sensor used to measure aberrations with a depth-resolved image-driven optimization algorithm, with the metric based on the OCT volumes acquired in real-time. The custom-built ultrahigh-speed GPU processing platform and fast modal optimization algorithm presented in this paper was essential in enabling real-time, in vivo imaging of human retinas with wavefront sensorless AO correction. WSAO-OCT is especially advantageous for developing a clinical high-resolution retinal imaging system as it enables the use of a compact, low-cost and robust lens-based adaptive optics design. In this report, we describe our WSAO-OCT system for imaging the human photoreceptor mosaic in vivo. We validated our system performance by imaging the retina at several eccentricities, and demonstrated the improvement in photoreceptor visibility with WSAO compensation. PMID:25780747

  5. In vivo imaging of human photoreceptor mosaic with wavefront sensorless adaptive optics optical coherence tomography.

    PubMed

    Wong, Kevin S K; Jian, Yifan; Cua, Michelle; Bonora, Stefano; Zawadzki, Robert J; Sarunic, Marinko V

    2015-02-01

    Wavefront sensorless adaptive optics optical coherence tomography (WSAO-OCT) is a novel imaging technique for in vivo high-resolution depth-resolved imaging that mitigates some of the challenges encountered with the use of sensor-based adaptive optics designs. This technique replaces the Hartmann Shack wavefront sensor used to measure aberrations with a depth-resolved image-driven optimization algorithm, with the metric based on the OCT volumes acquired in real-time. The custom-built ultrahigh-speed GPU processing platform and fast modal optimization algorithm presented in this paper was essential in enabling real-time, in vivo imaging of human retinas with wavefront sensorless AO correction. WSAO-OCT is especially advantageous for developing a clinical high-resolution retinal imaging system as it enables the use of a compact, low-cost and robust lens-based adaptive optics design. In this report, we describe our WSAO-OCT system for imaging the human photoreceptor mosaic in vivo. We validated our system performance by imaging the retina at several eccentricities, and demonstrated the improvement in photoreceptor visibility with WSAO compensation.

  6. Adaptive optics; Proceedings of the Meeting, Arlington, VA, April 10, 11, 1985

    NASA Astrophysics Data System (ADS)

    Ludman, J. E.

    Papers are presented on the directed energy program for ballistic missile defense, a self-referencing wavefront interferometer for laser sources, the effects of mirror grating distortions on diffraction spots at wavefront sensors, and the optical design of an all-reflecting, high-resolution camera for active-optics on ground-based telescopes. Also considered are transverse coherence length observations, time dependent statistics of upper atmosphere optical turbulence, high altitude acoustic soundings, and the Cramer-Rao lower bound on wavefront sensor error. Other topics include wavefront reconstruction from noisy slope or difference data using the discrete Fourier transform, acoustooptic adaptive signal processing, the recording of phase deformations on a PLZT wafer for holographic and spatial light modulator applications, and an optical phase reconstructor using a multiplier-accumulator approach. Papers are also presented on an integrated optics wavefront measurement sensor, a new optical preprocessor for automatic vision systems, a model for predicting infrared atmospheric emission fluctuations, and optical logic gates and flip-flops based on polarization-bistable semiconductor lasers.

  7. Pupil-segmentation-based adaptive optical microscopy with full-pupil illumination.

    PubMed

    Milkie, Daniel E; Betzig, Eric; Ji, Na

    2011-11-01

    Optical aberrations deteriorate the performance of microscopes. Adaptive optics can be used to improve imaging performance via wavefront shaping. Here, we demonstrate a pupil-segmentation based adaptive optical approach with full-pupil illumination. When implemented in a two-photon fluorescence microscope, it recovers diffraction-limited performance and improves imaging signal and resolution.

  8. Computational adaptive optics for broadband optical interferometric tomography of biological tissue.

    PubMed

    Adie, Steven G; Graf, Benedikt W; Ahmad, Adeel; Carney, P Scott; Boppart, Stephen A

    2012-05-08

    Aberrations in optical microscopy reduce image resolution and contrast, and can limit imaging depth when focusing into biological samples. Static correction of aberrations may be achieved through appropriate lens design, but this approach does not offer the flexibility of simultaneously correcting aberrations for all imaging depths, nor the adaptability to correct for sample-specific aberrations for high-quality tomographic optical imaging. Incorporation of adaptive optics (AO) methods have demonstrated considerable improvement in optical image contrast and resolution in noninterferometric microscopy techniques, as well as in optical coherence tomography. Here we present a method to correct aberrations in a tomogram rather than the beam of a broadband optical interferometry system. Based on Fourier optics principles, we correct aberrations of a virtual pupil using Zernike polynomials. When used in conjunction with the computed imaging method interferometric synthetic aperture microscopy, this computational AO enables object reconstruction (within the single scattering limit) with ideal focal-plane resolution at all depths. Tomographic reconstructions of tissue phantoms containing subresolution titanium-dioxide particles and of ex vivo rat lung tissue demonstrate aberration correction in datasets acquired with a highly astigmatic illumination beam. These results also demonstrate that imaging with an aberrated astigmatic beam provides the advantage of a more uniform depth-dependent signal compared to imaging with a standard gaussian beam. With further work, computational AO could enable the replacement of complicated and expensive optical hardware components with algorithms implemented on a standard desktop computer, making high-resolution 3D interferometric tomography accessible to a wider group of users and nonspecialists.

  9. Middleware for dynamic adaptation of component applications.

    SciTech Connect

    Norris, B.; Bhowmick, S.; Kaushik, D.; McInnes, L. C.

    2007-01-01

    Component- and service-based software engineering approaches have been gaining popularity in high-performance scientific computing, facilitating the creation and management of large multidisciplinary, multideveloper applications, and providing opportunities for improved performance and numerical accuracy. These software engineering approaches enable the development of middleware infrastructure for computational quality of service (CQoS), which provides performance optimizations through dynamic algorithm selection and configuration in a mostly automated fashion. The factors that affect performance are closely tied to a component's parallel implementation, its management of parallel communication and memory, the algorithms executed, the algorithmic parameters employed, and other operational characteristics. We present the design of a component middleware CQoS architecture for automated composition and adaptation of high-performance component- or service-based applications. We describe its initial implementation and corresponding experimental results for parallel simulations involving time-dependent nonlinear partial differential equations.

  10. Combinatorial Chemistry for Optical Sensing Applications

    NASA Astrophysics Data System (ADS)

    Díaz-García, M. E.; Luis, G. Pina; Rivero-Espejel, I. A.

    The recent interest in combinatorial chemistry for the synthesis of selective recognition materials for optical sensing applications is presented. The preparation, screening, and applications of libraries of ligands and chemosensors against molecular species and metal ions are first considered. Included in this chapter are also the developments involving applications of combinatorial approaches to the discovery of sol-gel and acrylic-based imprinted materials for optical sensing of antibiotics and pesticides, as well as libraries of doped sol-gels for high-throughput optical sensing of oxygen. The potential of combinatorial chemistry applied to the discovery of new sensing materials is highlighted.

  11. Adaptive optics wide-field microscopy using direct wavefront sensing

    NASA Astrophysics Data System (ADS)

    Azucena, Oscar A.

    I present a new technique for measuring and correcting the wavefront aberrations introduced when imaging through thick biological samples. The aberrations are due to the inhomogeneous nature of the biological samples and immersion media. In particular are the small changes in the index of refraction from point to point as the light travels through the thick tissue. The technique uses existing Adaptive Optics (AO) technology and incorporates it into a wide-field microscope. The apparatus consists of a Shack-Hartmann Wavefront Sensor (SHWS) to measure wavefronts emitted by a fluorescent light source within the biological tissue. A Micro-Electro-Mechanical System (MEMS) deformable mirror (DM) is used to correct the aberrations via a feedback control system. The advantage of this method is that the reference source can be the object that is being imaged or a spectrally separate object in the sample, the only requirements being that the reference source is sufficiently bright and has a small spatial extension when imaged by the SHWS. I will describe in detail the developments of the Adaptive Optics Wide-field Microscope (AOWFM) and its performance.

  12. Adaptive Optics Imaging Survey of Luminous Infrared Galaxies

    SciTech Connect

    Laag, E A; Canalizo, G; van Breugel, W; Gates, E L; de Vries, W; Stanford, S A

    2006-03-13

    We present high resolution imaging observations of a sample of previously unidentified far-infrared galaxies at z < 0.3. The objects were selected by cross-correlating the IRAS Faint Source Catalog with the VLA FIRST catalog and the HST Guide Star Catalog to allow for adaptive optics observations. We found two new ULIGs (with L{sub FIR} {ge} 10{sup 12} L{sub {circle_dot}}) and 19 new LIGs (with L{sub FIR} {ge} 10{sup 11} L{sub {circle_dot}}). Twenty of the galaxies in the sample were imaged with either the Lick or Keck adaptive optics systems in H or K{prime}. Galaxy morphologies were determined using the two dimensional fitting program GALFIT and the residuals examined to look for interesting structure. The morphologies reveal that at least 30% are involved in tidal interactions, with 20% being clear mergers. An additional 50% show signs of possible interaction. Line ratios were used to determine powering mechanism; of the 17 objects in the sample showing clear emission lines--four are active galactic nuclei and seven are starburst galaxies. The rest exhibit a combination of both phenomena.

  13. NAOMI: a new adaptive optics module for interferometry

    NASA Astrophysics Data System (ADS)

    Aller-Carpentier, Emmanuel; Dorn, Reinhold; Delplancke-Stroebele, Francoise; Paufique, Jérome; Andolfato, Luigi; Dupuy, Christophe; Fedrigo, Enrico; Gitton, Philippe; Jolley, Paul; Lilley, Paul; Le Louarn, Miska; Duc, Than P.; Rakich, Andrew; Reyes, Javier; Ridings, Robert; Woillez, Julien; Marchetti, Enrico; Suarez Valles, Marcos; Schmid, Christian; Hubin, Norbert; Berger, Jean-Philippe; Quentin, Jutta; Delabre, Bernard-Alexis; McLay, Stewart; Pasquini, Luca

    2014-07-01

    The New Adaptive Optics Module for Interferometry (NAOMI)1 is the future low order adaptive optics system to be developed for and installed at the ESO 1.8 m Auxiliary Telescopes (ATs). The four ATs2 are designed for interferometry which they are essentially dedicated for. Currently the AT's are equipped with a fast, visible tip-tilt sensor called STRAP3 (System for Tip/tilt Removal with Avalanche Photodiodes), and the corrections are applied through a tip-tilt mirror. The goal is to equip all four ATs with a low-order Shack-Hartmann system operating in the visible for the VLTI dual feed light beams in place of the current tip-tilt correction. Because of the limited size of the ATs (1.8m diameter), a low-order system will be sufficient. The goal is to concentrate the energy into a coherent core and to make the encircled energy (into the single mode fibers) stable and less dependent on the atmospheric conditions in order to increase the sensitivity of the interferometric instruments. The system will use the ESO real time computer platform Sparta-light as the baseline. This paper presents the preliminary design concept and outlines the benefits to current and future VLTI instruments.

  14. A New, Adaptable, Optical High-Resolution 3-Axis Sensor.

    PubMed

    Buchhold, Niels; Baumgartner, Christian

    2017-01-27

    This article presents a new optical, multi-functional, high-resolution 3-axis sensor which serves to navigate and can, for example, replace standard joysticks in medical devices such as electric wheelchairs, surgical robots or medical diagnosis devices. A light source, e.g., a laser diode, is affixed to a movable axis and projects a random geometric shape on an image sensor (CMOS or CCD). The downstream microcontroller's software identifies the geometric shape's center, distortion and size, and then calculates x, y, and z coordinates, which can be processed in attached devices. Depending on the image sensor in use (e.g., 6.41 megapixels), the 3-axis sensor features a resolution of 1544 digits from right to left and 1038 digits up and down. Through interpolation, these values rise by a factor of 100. A unique feature is the exact reproducibility (deflection to coordinates) and its precise ability to return to its neutral position. Moreover, optical signal processing provides a high level of protection against electromagnetic and radio frequency interference. The sensor is adaptive and adjustable to fit a user's range of motion (stroke and force). This recommendation aims to optimize sensor systems such as joysticks in medical devices in terms of safety, ease of use, and adaptability.

  15. AVES: an adaptive optics visual echelle spectrograph for the VLT

    NASA Astrophysics Data System (ADS)

    Pasquini, Luca; Delabre, Bernard; Avila, Gerardo; Bonaccini, Domenico

    1998-07-01

    We present the preliminary study of a low cost, high performance spectrograph for the VLT, for observations in the V, R and I bands. This spectrograph is meant for intermediate (R equals 16,000) resolution spectroscopy of faint (sky and/or detector limited) sources, with particular emphasis on the study of solar-type (F-G) stars belonging to the nearest galaxies and to distant (or highly reddened) galactic clusters. The spectrograph is designed to use the adaptive optics (AO) systems at the VLT Telescope. Even if these AO systems will not provide diffraction limited images in the V, R and I bands, the photon concentration will still be above approximately 60% of the flux in an 0.3 arcsecond aperture for typical Paranal conditions. This makes the construction of a compact, cheap and efficient echelle spectrograph possible. AVES will outperform comparable non adaptive optic instruments by more than one magnitude for sky- and/or detector-limited observations, and it will be very suitable for observations in crowded fields.

  16. Non-iterative adaptive optical microscopy using wavefront sensing

    NASA Astrophysics Data System (ADS)

    Tao, X.; Azucena, O.; Kubby, J.

    2016-03-01

    This paper will review the development of wide-field and confocal microscopes with wavefront sensing and adaptive optics for correcting refractive aberrations and compensating scattering when imaging through thick tissues (Drosophila embryos and mouse brain tissue). To make wavefront measurements in biological specimens we have modified the laser guide-star techniques used in astronomy for measuring wavefront aberrations that occur as star light passes through Earth's turbulent atmosphere. Here sodium atoms in Earth's mesosphere, at an altitude of 95 km, are excited to fluoresce at resonance by a high-power sodium laser. The fluorescent light creates a guide-star reference beacon at the top of the atmosphere that can be used for measuring wavefront aberrations that occur as the light passes through the atmosphere. We have developed a related approach for making wavefront measurements in biological specimens using cellular structures labeled with fluorescent proteins as laser guide-stars. An example is a fluorescently labeled centrosome in a fruit fly embryo or neurons and dendrites in mouse brains. Using adaptive optical microscopy we show that the Strehl ratio, the ratio of the peak intensity of an aberrated point source relative to the diffraction limited image, can be improved by an order of magnitude when imaging deeply into live dynamic specimens, enabling near diffraction limited deep tissue imaging.

  17. Distributed control in adaptive optics: deformable mirror and turbulence modeling

    NASA Astrophysics Data System (ADS)

    Ellenbroek, Rogier; Verhaegen, Michel; Doelman, Niek; Hamelinck, Roger; Rosielle, Nick; Steinbuch, Maarten

    2006-06-01

    Future large optical telescopes require adaptive optics (AO) systems whose deformable mirrors (DM) have ever more degrees of freedom. This paper describes advances that are made in a project aimed to design a new AO system that is extendible to meet tomorrow's specifications. Advances on the mechanical design are reported in a companion paper [6272-75], whereas this paper discusses the controller design aspects. The numerical complexity of controller designs often used for AO scales with the fourth power in the diameter of the telescope's primary mirror. For future large telescopes this will undoubtedly become a critical aspect. This paper demonstrates the feasibility of solving this issue with a distributed controller design. A distributed framework will be introduced in which each actuator has a separate processor that can communicate with a few direct neighbors. First, the DM will be modeled and shown to be compatible with the framework. Then, adaptive turbulence models that fit the framework will be shown to adequately capture the spatio-temporal behavior of the atmospheric disturbance, constituting a first step towards a distributed optimal control. Finally, the wavefront reconstruction step is fitted into the distributed framework such that the computational complexity for each processor increases only linearly with the telescope diameter.

  18. Adaptive optics observations of the core of Cygnus A

    NASA Astrophysics Data System (ADS)

    Max, C. E.; Whysong, D.; Antonucci, R.; Canalizo, G.; Macintosh, B. A.; Stockton, A.

    2001-12-01

    We report on near-infrared imaging and spectroscopy of the core of Cygnus A, using adaptive optics systems at the Lick and Keck Observatories. In our images, a V-shaped ionization cone structure is seen to the south-east of the nucleus, as in previous HST NICMOS observations. To the north-west of the nucleus are two diffuse emission regions. We have obtained K-band spectra of these regions and of the nucleus. Paschen alpha spectra show emission near the nucleus with FWHM 1000 km/s. The diffuse emission regions to the north-west and south-east have narrower linewidths. We interpret these data in terms of models for the core of Cygnus A. This work was performed under the auspices of the U.S. Department of Energy, National Nuclear Security Administration by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48, and was supported in part by the National Science Foundation Science and Technology Center for Adaptive Optics, managed by the University of California at Santa Cruz under cooperative agreement No. AST - 9876783.

  19. Cloud Structures on Neptune Observed with Keck Telescope Adaptive Optics

    NASA Astrophysics Data System (ADS)

    Max, C. E.; Macintosh, B. A.; Gibbard, S. G.; Gavel, D. T.; Roe, H. G.; de Pater, I.; Ghez, A. M.; Acton, D. S.; Lai, O.; Stomski, P.; Wizinowich, P. L.

    2003-01-01

    We report on observations obtained with the adaptive optics system at the 10 m Keck II Telescope during engineering validation and early science observing time for the adaptive optics system. We observed Neptune at near-infrared wavelengths. Angular resolution was 0.05"-0.06", corresponding to a spatial scale of approximately 1000 km at Neptune. We discuss the latitudinal structure of circumferential cloud bands and of compact infrared-bright features seen in the southern hemisphere, as well as their variation with wavelength. We determine the values of I/F (proportional to the ratio of reflected intensity to incident solar flux) in the J and H infrared-wavelength bands, including narrowband filters where there is strong methane absorption. We use the I/F values inside and outside of methane bands to estimate the altitude of clouds responsible for the brightest compact features in the infrared. Our data show that, on two of our four observing dates, the brightest region on Neptune contained highly reflective haze layers located below the tropopause but not deeper than a few bars.

  20. Overview of deformable mirror technologies for adaptive optics and astronomy

    NASA Astrophysics Data System (ADS)

    Madec, P.-Y.

    2012-07-01

    From the ardent bucklers used during the Syracuse battle to set fire to Romans’ ships to more contemporary piezoelectric deformable mirrors widely used in astronomy, from very large voice coil deformable mirrors considered in future Extremely Large Telescopes to very small and compact ones embedded in Multi Object Adaptive Optics systems, this paper aims at giving an overview of Deformable Mirror technology for Adaptive Optics and Astronomy. First the main drivers for the design of Deformable Mirrors are recalled, not only related to atmospheric aberration compensation but also to environmental conditions or mechanical constraints. Then the different technologies available today for the manufacturing of Deformable Mirrors will be described, pros and cons analyzed. A review of the Companies and Institutes with capabilities in delivering Deformable Mirrors to astronomers will be presented, as well as lessons learned from the past 25 years of technological development and operation on sky. In conclusion, perspective will be tentatively drawn for what regards the future of Deformable Mirror technology for Astronomy.