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Sample records for large aperture optical

  1. 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.

  2. Very large aperture optics for space applications

    NASA Astrophysics Data System (ADS)

    Horwath, T. G.; Smith, J. P.; Johnson, M. T.

    1994-09-01

    A new type of space optics technology is presented which promises the realization of very large apertures (tens of meters), while packagable into lightweight, small volume containers compatible with conventional launch vehicles. This technology makes use of thin foils of circular shape which are uniformly mass loaded around the perimeter. Once unfurled and set into rapid rotation about the transversal axis, the foil is stretched into a perfectly flat plane by the centrifugal forces acting on the peripheral masses. The simplest applications of this novel technology are optically flat reflectors, using metallized foils of Mylar, Kevlar, or Kapton. Other more complex optical components can be realized by use of binary optics techniques, such as depositing holograms by selective local microscale removal of the reflective surface. Electrostatic techniques, in conjunction with an auxiliary foil, under local, distributed real-time control of the optical parameters, allow implementation of functions like beam steering and focal length adjustments. Gas pressurization allows stronger curvatures and thus smaller focal ratios for non-imaging applications. Limits on aperture are imposed primarily by manufacturing capabilities. Applications of such large optics in space are numerous. They range from military, such as space based lasers, to the civilian ones of power beaming, solar energy collection, and astronomy. This paper examines this simple and innovative concept in detail, discusses deployment and attitude control issues and presents approaches for realization.

  3. 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.

  4. Design of precise assembly equipment of large aperture optics

    NASA Astrophysics Data System (ADS)

    Pei, Guoqing; Xu, Xu; Xiong, Zhao; Yan, Han; Qin, Tinghai; Zhou, Hai; Yuan, Xiaodong

    2017-05-01

    High-energy solid-state laser is an important way to achieve laser fusion research. Laser fusion facility includes thousands of various types of large aperture optics. These large aperture optics should be assembled with high precision and high efficiency. Currently, however, the assembly of large aperture optics is by man's hand which is in low level of efficiency and labor-intensive. Here, according to the characteristics of the assembly of large aperture optics, we designed three kinds of grasping devices. Using Finite Element Method, we simulated the impact of the grasping device on the PV value and the RMS value of the large aperture optics. The structural strength of the grasping device's key part was analyzed. An experiment was performed to illustrate the reliability and precision of the grasping device. We anticipate that the grasping device would complete the assembly of large aperture optics precisely and efficiently.

  5. Large Aperture, Narrow-Band Detectors for Optical Communication Systems.

    DTIC Science & Technology

    The patent application provides a sensitive detector means for the reception and detection of optical communication signals which are accompanied by...onto a detector. A provision of a large aperture narrow-band detector for optical communication systems is made for receiving and detecting optical ... communication with self-filtering to selectively detect the information while discriminating or rejecting background radiation.

  6. Large aperture ac interferometer for optical testing.

    PubMed

    Moore, D T; Murray, R; Neves, F B

    1978-12-15

    A 20-cm clear aperture modified Twyman-Green interferometer is described. The system measures phase with an AC technique called phase-lock interferometry while scanning the aperture with a dual galvanometer scanning system. Position information and phase are stored in a minicomputer with disk storage. This information is manipulated with associated software, and the wavefront deformation due to a test component is graphically displayed in perspective and contour on a CRT terminal.

  7. Fabrication and applications of large aperture diffractive optics

    SciTech Connect

    Dixit, S; Britten, J B; Hyde, R; Rushford, M; Summers, L; Toeppen, J

    2002-02-19

    Large aperture diffractive optics are needed in high power laser applications to protect against laser damage during operation and in space applications to increase the light gathering power and consequently the signal to noise. We describe the facilities we have built for fabricating meter scale diffractive optics and discuss several examples of these.

  8. Large Aperture Multiplexed Diffractive Lidar Optics

    NASA Technical Reports Server (NTRS)

    Rallison, Richard D.; Schwemmer, Geary K. (Technical Monitor)

    1999-01-01

    We have delivered only 2 or 3 UV Holographic Optical Elements (HOEs) thus far and have fallen short of the intended goal in size and in dual wavelength function. Looking back, it has been fortuitous that we even made anything work in the UV region. It was our good fortune to discover that the material we work with daily was adequate for use at 355 nm, if well rinsed during processing. If we had stuck to our original plan of etching in small pieces of fused silica, we would still be trying to make the first small section in our ion mill, which is not yet operational. The original plan was far too ambitious and would take another 2 years to complete beginning where we left off this time. In order to make a HOE for the IR as well as the UV we will likely have to learn to sensitize some film to the 1064 line and we have obtained sensitizer that is reported to work in that region already. That work would also take an additional year to complete.

  9. Low-cost Large Aperture Telescopes for Optical Communications

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid

    2006-01-01

    Low-cost, large-aperture optical receivers are required to form an affordable optical ground receiver network for laser communications. Among the ground receiver station's multiple subsystems, here, we only discuss the ongoing research activities aimed at reducing the cost of the large-size optics on the receiver. Experimental results of two different approaches for fabricating low-cost mirrors of wavefront quality on the order of 100-200X the diffraction limit are described. Laboratory-level effort are underway to improve the surface figure to better than 20X the diffraction limit.

  10. Low-cost Large Aperture Telescopes for Optical Communications

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid

    2006-01-01

    Low-cost, large-aperture optical receivers are required to form an affordable optical ground receiver network for laser communications. Among the ground receiver station's multiple subsystems, here, we only discuss the ongoing research activities aimed at reducing the cost of the large-size optics on the receiver. Experimental results of two different approaches for fabricating low-cost mirrors of wavefront quality on the order of 100-200X the diffraction limit are described. Laboratory-level effort are underway to improve the surface figure to better than 20X the diffraction limit.

  11. Large-aperture, high-damage-threshold optics for beamlet

    SciTech Connect

    Campbell, J.H.; Atherton, L.J.; DeYoreo, J.J.

    1996-06-01

    Beamlet serves as a test bed for the proposed National Ignition Facility (NIF) laser design and components. Therefore, its optics are similar in size and quality to those proposed for the NIF. In general, the optics in the main laser cavity and transport section of Beamlet are larger and have higher damage thresholds than the optics manufactured for any of the previous laser systems. In addition, the quality of the Beamlet optical materials is higher, leading to better wavefront quality, higher optical transmission, and lower-intensity modulation of the output laser beam than, for example, that typically achieved on Nova. In this article, the authors discuss the properties and characteristics of the large-aperture optics used on Beamlet.

  12. Large-aperture, high-damage-threshold optics for beamlet

    SciTech Connect

    Campbell, J.H.; Atherton, L.J.; DeYoreo, J.J.; Kozlowski, M.R.; Maney, R.T.; Montesanti, R.C.; Sheehan, L.M.; Barker, C.E.

    1995-02-23

    Beamlet serves as a test bed for the proposed NIF laser design and components. Therefore, its optics are similar in size and quality to those proposed for the NIF. In general, the optics in the main laser cavity and transport section of Beamlet are larger and have higher damage thresholds than the optics manufactured for any of our previous laser systems. In addition, the quality of the Beamlet optical materials is higher, leading to better wavefront quality, higher optical transmission, and lower-intensity modulation of the output laser beam than, for example, that typically achieved on Nova. In this article, we discuss the properties and characteristics of the large-aperture optics used on Beamlet.

  13. Phased Array Mirror Extendible Large Aperture (PAMELA) Optics Adjustment

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Scientists at Marshall's Adaptive Optics Lab demonstrate the Wave Front Sensor alignment using the Phased Array Mirror Extendible Large Aperture (PAMELA) optics adjustment. The primary objective of the PAMELA project is to develop methods for aligning and controlling adaptive optics segmented mirror systems. These systems can be used to acquire or project light energy. The Next Generation Space Telescope is an example of an energy acquisition system that will employ segmented mirrors. Light projection systems can also be used for power beaming and orbital debris removal. All segmented optical systems must be adjusted to provide maximum performance. PAMELA is an on going project that NASA is utilizing to investigate various methods for maximizing system performance.

  14. Phased Array Mirror Extendible Large Aperture (PAMELA) Optics Adjustment

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Scientists at Marshall's Adaptive Optics Lab demonstrate the Wave Front Sensor alignment using the Phased Array Mirror Extendible Large Aperture (PAMELA) optics adjustment. The primary objective of the PAMELA project is to develop methods for aligning and controlling adaptive optics segmented mirror systems. These systems can be used to acquire or project light energy. The Next Generation Space Telescope is an example of an energy acquisition system that will employ segmented mirrors. Light projection systems can also be used for power beaming and orbital debris removal. All segmented optical systems must be adjusted to provide maximum performance. PAMELA is an on going project that NASA is utilizing to investigate various methods for maximizing system performance.

  15. Refractive index homogeneity TWE effect on large aperture optical systems

    NASA Astrophysics Data System (ADS)

    Stout, M.; Neff, B.

    2017-05-01

    Sapphire windows are routinely being used in demanding aerospace applications due to their high strength and desirable optical and material properties. Sapphire is particularly useful in addressing the increasing need for systems that provide a wider range of capabilities in a single package. In general, refractive index homogeneity of the component materials can have a significant impact on overall optical system performance. This leads to the need for a deeper understanding of the shape and magnitude of index inhomogeneity in large sapphire windows to ensure predictable, high quality operation. Thin, sapphire slices from a sapphire crystal boule grown via the Heat Exchanger Method (HEM) have been previously evaluated for refractive index homogeneity over a 25.4cm (10.0") aperture. The resultant transmitted wavefront error (TWE) from those measurements has now been used to model typical optical systems to quantify the effects on system-level performance attributed to representative amounts of index inhomogeneity in the sapphire window. The results of this modeling effort are presented in the following paper.

  16. Structural-optical integrated analysis on the large aperture mirror with active mounting

    NASA Astrophysics Data System (ADS)

    Ren, Zhiyuan; Zhu, Jianqiang; Liu, Zhigang

    2016-11-01

    Deformation of the large aperture mirror caused by the external environment load seriously affects the optical performance of the optical system, and there is a limit to develop the shape quality of large aperture mirror with traditional mounting method. It is effective way to reduce the optical mirror distortion with active support method, and the structural-optical integrated method is the effective means to assess the merits of the mounting for large aperture mirror. Firstly, we proposes a new support scheme that uses specific boundary constraints on the large lens edges and imposes flexible torque to resist deformation induced by gravity to improve surface quantity of large aperture mirror. We calculate distortion of the large aperture mirror at the edges of the flexible torque respectively with the finite element method; secondly, we extract distortion value within clear aperture of the mirror with MATLAB, solve the corresponding Zernike polynomial coefficients; lastly, we obtain the peak-valley value (PV) and root mean square value (RMS) with optical-structural integrated analysis . The results for the 690x400x100mm mirror show that PV and RMS values within the clear aperture with 0.4MPa torques than the case without applying a flexible torque reduces 82.7% and 72.9% respectively. The active mounting on the edge of the large aperture mirror can greatly improve the surface quality of the large aperture mirror.

  17. A Large Aperture, High Energy Laser System for Optics and Optical Component Testing

    SciTech Connect

    Nostrand, M C; Weiland, T L; Luthi, R L; Vickers, J L; Sell, W D; Stanley, J A; Honig, J; Auerbach, J; Hackel, R P; Wegner, P J

    2003-11-01

    A large aperture, kJ-class, multi-wavelength Nd-glass laser system has been constructed at Lawrence Livermore National Lab which has unique capabilities for studying a wide variety of optical phenomena. The master-oscillator, power-amplifier (MOPA) configuration of this ''Optical Sciences Laser'' (OSL) produces 1053 nm radiation with shaped pulse lengths which are variable from 0.1-100 ns. The output can be frequency doubled or tripled with high conversion efficiency with a resultant 100 cm{sup 2} high quality output beam. This facility can accommodate prototype hardware for large-scale inertial confinement fusion lasers allowing for investigation of integrated system issues such as optical lifetime at high fluence, optics contamination, compatibility of non-optical materials, and laser diagnostics.

  18. Fabrication of large-aperture, high efficiency, Fresnel diffractive membrane optic for space telescope

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Li, Mengjuan; Yin, Ganghua; Jiao, Jianchao; Liu, Zhengkun; Xu, Xiangdong; Fu, Shaojun

    2016-10-01

    Diffractive optical system can be a favorable choice for large-aperture space telescope to reduce the mass and size of image system. To meet the demand of large-aperture, high efficiency, lightweight diffractive optic for high resolution remote sensing, a 200 mm diameter, 20 μmthick, 4-level diffractive membrane fabricated is shown to have over 62% diffraction efficiency into the +1 order, with 0.051 efficiency RMS. Over 66% diffraction efficiency is achieved for a 100 mm aperture membrane, with 0.023 efficiency RMS. The membrane thickness uniformity control is discussed and 8 nm wave front error RMS is achieved in 100 mm diameter.

  19. Large Aperture Scanning Lidar Based on Holographic Optical Elements

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary K.; Miller, David O.; Wilkerson, Thomas D.; Andrus, Ionio; Guerra, David V.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Lidar remote sensing instruments can make a significant contribution to satisfying many of the required measurements of atmospheric and surface parameters for future spaceborne platforms, including topographic altimeters, atmospheric profiles of, wind, humidity, temperature, trace molecules, aerosols, and clouds. It is highly desirable to have wide measurement swaths for rapid coverage rather than just the narrow ribbon of data that is obtained with a nadir only observation. For most applications global coverage is required, and for wind measurements scanning or pointing is required in order to retrieve the full 3-D wind vector from multiple line-of-sight Doppler measurements. Conventional lidar receivers make up a substantial portion of the instrument's size and weight. Wide angle scanning typically requires a large scanning mirror in front of the receiver telescope, or pointing the entire telescope and aft optics assembly, Either of these methods entails the use of large bearings, motors, gearing and their associated electronics. Spaceborne instruments also need reaction wheels to counter the torque applied to the spacecraft by these motions. NASA has developed simplified conical scanning telescopes using Holographic Optical Elements (HOEs) to reduce the size, mass, angular momentum, and cost of scanning lidar systems. NASA has developed two operating lidar systems based on 40 cm diameter HOEs. The first such system, named Prototype Holographic Atmospheric Scanner for Environmental Remote Sensing (PHASERS) was a joint development between NASA Goddard Space Flight Center (GSFC) and the University of Maryland College Park. PHASERS is based on a reflection HOE for use at the doubled Nd:YAG laser wavelength of 532 nm and has recently undergone a number of design changes in a collaborative effort between GSFC and Saint Anselm College in New Hampshire. The next step was to develop IR transmission HOEs for use with the Nd:YAG fundamental in the Holographic Airborne

  20. Large Aperture Scanning Lidar Based on Holographic Optical Elements

    NASA Technical Reports Server (NTRS)

    Schwemmer, Geary K.; Miller, David O.; Wilkerson, Thomas D.; Andrus, Ionio; Guerra, David V.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Lidar remote sensing instruments can make a significant contribution to satisfying many of the required measurements of atmospheric and surface parameters for future spaceborne platforms, including topographic altimeters, atmospheric profiles of, wind, humidity, temperature, trace molecules, aerosols, and clouds. It is highly desirable to have wide measurement swaths for rapid coverage rather than just the narrow ribbon of data that is obtained with a nadir only observation. For most applications global coverage is required, and for wind measurements scanning or pointing is required in order to retrieve the full 3-D wind vector from multiple line-of-sight Doppler measurements. Conventional lidar receivers make up a substantial portion of the instrument's size and weight. Wide angle scanning typically requires a large scanning mirror in front of the receiver telescope, or pointing the entire telescope and aft optics assembly, Either of these methods entails the use of large bearings, motors, gearing and their associated electronics. Spaceborne instruments also need reaction wheels to counter the torque applied to the spacecraft by these motions. NASA has developed simplified conical scanning telescopes using Holographic Optical Elements (HOEs) to reduce the size, mass, angular momentum, and cost of scanning lidar systems. NASA has developed two operating lidar systems based on 40 cm diameter HOEs. The first such system, named Prototype Holographic Atmospheric Scanner for Environmental Remote Sensing (PHASERS) was a joint development between NASA Goddard Space Flight Center (GSFC) and the University of Maryland College Park. PHASERS is based on a reflection HOE for use at the doubled Nd:YAG laser wavelength of 532 nm and has recently undergone a number of design changes in a collaborative effort between GSFC and Saint Anselm College in New Hampshire. The next step was to develop IR transmission HOEs for use with the Nd:YAG fundamental in the Holographic Airborne

  1. Research and validation of key measurement technologies of large aperture optical elements

    NASA Astrophysics Data System (ADS)

    Guo, Renhui; Chen, Lei; Jiang, Chao; Cao, Hui; Zhang, Huiqin; Zhou, Binbin; Song, Le

    2015-07-01

    A lot of optical components with large aperture are employed in high-power solid-state laser driver. These optical components are with high requirement on the surface shape, optical homogeneity and stress distribution. In order to test these parameters, different types of interferometers, surface profilers and stress meters from different manufacturers are needed. But the problem is the products from different manufacturers may provide different test results. To solve the problem, the research and verification of the key measurement technologies of large aperture optical components are carried out in this paper. The absolute flatness and optical homogeneity measurement methods are analyzed. And the test results of different interferometric software are compared. The test results from different surface profilers and stress meters are also compared. The consistency and reliability of different test software are obtained with the comparing results, which will guide users to select a suitable product.

  2. Large-aperture space optical system testing based on the scanning Hartmann.

    PubMed

    Wei, Haisong; Yan, Feng; Chen, Xindong; Zhang, Hao; Cheng, Qiang; Xue, Donglin; Zeng, Xuefeng; Zhang, Xuejun

    2017-03-10

    Based on the Hartmann testing principle, this paper proposes a novel image quality testing technology which applies to a large-aperture space optical system. Compared with the traditional testing method through a large-aperture collimator, the scanning Hartmann testing technology has great advantages due to its simple structure, low cost, and ability to perform wavefront measurement of an optical system. The basic testing principle of the scanning Hartmann testing technology, data processing method, and simulation process are presented in this paper. Certain simulation results are also given to verify the feasibility of this technology. Furthermore, a measuring system is developed to conduct a wavefront measurement experiment for a 200 mm aperture optical system. The small deviation (6.3%) of root mean square (RMS) between experimental results and interferometric results indicates that the testing system can measure low-order aberration correctly, which means that the scanning Hartmann testing technology has the ability to test the imaging quality of a large-aperture space optical system.

  3. Optical slicing of large scenes by synthetic aperture integral imaging

    NASA Astrophysics Data System (ADS)

    Navarro, Héctor; Saavedra, Genaro; Molina, Ainhoa; Martínez-Corral, Manuel; Martínez-Cuenca, Raúl; Javidi, Bahram

    2010-04-01

    Integral imaging (InI) technology was created with the aim of providing the binocular observers of monitors, or matrix display devices, with auto-stereoscopic images of 3D scenes. However, along the last few years the inventiveness of researches has allowed to find many other interesting applications of integral imaging. Examples of this are the application of InI in object recognition, the mapping of 3D polarization distributions, or the elimination of occluding signals. One of the most interesting applications of integral imaging is the production of views focused at different depths of the 3D scene. This application is the natural result of the ability of InI to create focal stacks from a single input image. In this contribution we present new algorithm for this optical slicing application, and show that it is possible the 3D reconstruction with improved lateral resolution.

  4. Large Aperture "Photon Bucket" Optical Receiver Performance in High Background Environments

    NASA Technical Reports Server (NTRS)

    Vilnrotter, Victor A.; Hoppe, D.

    2011-01-01

    The potential development of large aperture groundbased "photon bucket" optical receivers for deep space communications, with acceptable performance even when pointing close to the sun, is receiving considerable attention. Sunlight scattered by the atmosphere becomes significant at micron wavelengths when pointing to a few degrees from the sun, even with the narrowest bandwidth optical filters. In addition, high quality optical apertures in the 10-30 meter range are costly and difficult to build with accurate surfaces to ensure narrow fields-of-view (FOV). One approach currently under consideration is to polish the aluminum reflector panels of large 34-meter microwave antennas to high reflectance, and accept the relatively large FOV generated by state-of-the-art polished aluminum panels with rms surface accuracies on the order of a few microns, corresponding to several-hundred micro-radian FOV, hence generating centimeter-diameter focused spots at the Cassegrain focus of 34-meter antennas. Assuming pulse-position modulation (PPM) and Poisson-distributed photon-counting detection, a "polished panel" photon-bucket receiver with large FOV will collect hundreds of background photons per PPM slot, along with comparable signal photons due to its large aperture. It is demonstrated that communications performance in terms of PPM symbol-error probability in high-background high-signal environments depends more strongly on signal than on background photons, implying that large increases in background energy can be compensated by a disproportionally small increase in signal energy. This surprising result suggests that large optical apertures with relatively poor surface quality may nevertheless provide acceptable performance for deep-space optical communications, potentially enabling the construction of cost-effective hybrid RF/optical receivers in the future.

  5. Large Aperture "Photon Bucket" Optical Receiver Performance in High Background Environments

    NASA Technical Reports Server (NTRS)

    Vilnrotter, Victor A.; Hoppe, D.

    2011-01-01

    The potential development of large aperture groundbased "photon bucket" optical receivers for deep space communications, with acceptable performance even when pointing close to the sun, is receiving considerable attention. Sunlight scattered by the atmosphere becomes significant at micron wavelengths when pointing to a few degrees from the sun, even with the narrowest bandwidth optical filters. In addition, high quality optical apertures in the 10-30 meter range are costly and difficult to build with accurate surfaces to ensure narrow fields-of-view (FOV). One approach currently under consideration is to polish the aluminum reflector panels of large 34-meter microwave antennas to high reflectance, and accept the relatively large FOV generated by state-of-the-art polished aluminum panels with rms surface accuracies on the order of a few microns, corresponding to several-hundred micro-radian FOV, hence generating centimeter-diameter focused spots at the Cassegrain focus of 34-meter antennas. Assuming pulse-position modulation (PPM) and Poisson-distributed photon-counting detection, a "polished panel" photon-bucket receiver with large FOV will collect hundreds of background photons per PPM slot, along with comparable signal photons due to its large aperture. It is demonstrated that communications performance in terms of PPM symbol-error probability in high-background high-signal environments depends more strongly on signal than on background photons, implying that large increases in background energy can be compensated by a disproportionally small increase in signal energy. This surprising result suggests that large optical apertures with relatively poor surface quality may nevertheless provide acceptable performance for deep-space optical communications, potentially enabling the construction of cost-effective hybrid RF/optical receivers in the future.

  6. Technology gap assessment for a future large-aperture ultraviolet-optical-infrared space telescope

    NASA Astrophysics Data System (ADS)

    Bolcar, Matthew R.; Balasubramanian, Kunjithapatham; Crooke, Julie; Feinberg, Lee; Quijada, Manuel; Rauscher, Bernard J.; Redding, David; Rioux, Norman; Shaklan, Stuart; Stahl, H. Philip; Stahle, Carl M.; Thronson, Harley

    2016-10-01

    The Advanced Technology Large Aperture Space Telescope (ATLAST) team identified five key technology areas to enable candidate architectures for a future large-aperture ultraviolet/optical/infrared (LUVOIR) space observatory envisioned by the NASA Astrophysics 30-year roadmap, "Enduring Quests, Daring Visions." The science goals of ATLAST address a broad range of astrophysical questions from early galaxy and star formation to the processes that contributed to the formation of life on Earth, combining general astrophysics with direct-imaging and spectroscopy of habitable exoplanets. The key technology areas are internal coronagraphs, starshades (or external occulters), ultra-stable large-aperture telescope systems, detectors, and mirror coatings. For each technology area, we define best estimates of required capabilities, current state-of-the-art performance, and current technology readiness level (TRL), thus identifying the current technology gap. We also report on current, planned, or recommended efforts to develop each technology to TRL 5.

  7. Development of atmospheric pressure plasma processing machine tool for large aperture optics

    NASA Astrophysics Data System (ADS)

    Su, Xing; Wu, Yangong; Zhang, Peng; Xin, Qiang; Wang, Bo

    2016-10-01

    In recent years, major projects, such as National Ignition Facility and Laser Mégajoule, have generated great demands for large aperture optics with high surface accuracy and low Subsurface Damage (SSD) at the mean time. In order to remove SSD and improve surface quality, optics is fabricated by sub-aperture polishing. However, the efficiency of the sub-aperture polishing has been a bottleneck step for the optics manufacturing. Atmospheric Pressure Plasma Processing (APPP) as an alternate method offers high potential for speeding up the polishing process. This technique is based on chemical etching, hence there is no physical contact and no damage is induced. In this paper, a fast polishing machine tool is presented which is designed for fast polishing of the large aperture optics using APPP. This machine tool employs 3PRS-XY hybrid structure as its framework. There is a platform in the 3PRS parallel module to support the plasma generating system. And the large work piece is placed on the XY stage. In order to realize the complex motion trajectory for polishing the freeform optics, five axis of the tool operate simultaneously. To overcome the complexity of inverse kinematics calculation, a dedicated motion control system is also designed for speeding up the motion response. For high removal rate, the individual influence of several key processing parameters is investigated. And under specific production condition, this machine tool offers a high material over 30mm3/min for fused silica substrates. This results shows that APPP machine tool has a strong potential for fast polishing large optics without introducing SSD.

  8. Eyeglass Large Aperture, Lightweight Space Optics FY2000 - FY2002 LDRD Strategic Initiative

    SciTech Connect

    Hyde, R

    2003-02-10

    A series of studies by the Air Force, the National Reconnaissance Office and NASA have identified the critical role played by large optics in fulfilling many of the space related missions of these agencies. Whether it is the Next Generation Space Telescope for NASA, high resolution imaging systems for NRO, or beam weaponry for the Air Force, the diameter of the primary optic is central to achieving high resolution (imaging) or a small spot size on target (lethality). While the detailed requirements differ for each application (high resolution imaging over the visible and near-infrared for earth observation, high damage threshold but single-wavelength operation for directed energy), the challenges of a large, lightweight primary optic which is space compatible and operates with high efficiency are the same. The advantage of such large optics to national surveillance applications is that it permits these observations to be carried-out with much greater effectiveness than with smaller optics. For laser weapons, the advantage is that it permits more tightly focused beams which can be leveraged into either greater effective range, reduced laser power, and/or smaller on-target spot-sizes; weapon systems can be made either much more effective or much less expensive. This application requires only single-wavelength capability, but places an emphasis upon robust, rapidly targetable optics. The advantages of large aperture optics to astronomy are that it increases the sensitivity and resolution with which we can view the universe. This can be utilized either for general purpose astronomy, allowing us to examine greater numbers of objects in more detail and at greater range, or it can enable the direct detection and detailed examination of extra-solar planets. This application requires large apertures (for both light-gathering and resolution reasons), with broad-band spectral capability, but does not emphasize either large fields-of-view or pointing agility. Despite

  9. Initial Technology Assessment for the Large-Aperture UV-Optical-Infrared (LUVOIR) Mission Concept Study

    NASA Technical Reports Server (NTRS)

    Bolcar, Matthew R.; Feinberg, Lee; France, Kevin; Rauscher, Bernard J.; Redding, David; Schiminovich, David

    2016-01-01

    The NASA Astrophysics Division's 30-Year Roadmap prioritized a future large-aperture space telescope operating in the ultra-violet/optical/infrared wavelength regime. The Association of Universities for Research in Astronomy envisioned a similar observatory, the High Definition Space Telescope. And a multi-institution group also studied the Advanced Technology Large Aperture Space Telescope. In all three cases, a broad science case is outlined, combining general astrophysics with the search for biosignatures via direct-imaging and spectroscopic characterization of habitable exoplanets. We present an initial technology assessment that enables such an observatory that is currently being studied for the 2020 Decadal Survey by the Large UV/Optical/Infrared (LUVOIR) surveyor Science and Technology Definition Team. We present here the technology prioritization for the 2016 technology cycle and define the required technology capabilities and current state-of-the-art performance. Current, planned, and recommended technology development efforts are also reported.

  10. Initial technology assessment for the Large-Aperture UV-Optical-Infrared (LUVOIR) mission concept study

    NASA Astrophysics Data System (ADS)

    Bolcar, Matthew R.; Feinberg, Lee; France, Kevin; Rauscher, Bernard J.; Redding, David; Schiminovich, David

    2016-07-01

    The NASA Astrophysics Division's 30-Year Roadmap prioritized a future large-aperture space telescope operating in the ultra-violet/optical/infrared wavelength regime. The Association of Universities for Research in Astronomy envisioned a similar observatory, the High Definition Space Telescope. And a multi-institution group also studied the Advanced Technology Large Aperture Space Telescope. In all three cases, a broad science case is outlined, combining general astrophysics with the search for biosignatures via direct-imaging and spectroscopic characterization of habitable exoplanets. We present an initial technology assessment that enables such an observatory that is currently being studied for the 2020 Decadal Survey by the Large UV/Optical/Infrared (LUVOIR) surveyor Science and Technology Definition Team. We present here the technology prioritization for the 2016 technology cycle and define the required technology capabilities and current state-of-the-art performance. Current, planned, and recommended technology development efforts are also reported.

  11. Imprinting continuously varying topographical structure onto large-aperture optical surfaces using magnetorheological finishing

    SciTech Connect

    Menapace, J A; Davis, P J; Dixit, S; Campbell, J H; Golini, D; Hachkowski, M R; Nelson, A

    2007-03-07

    Over the past four years we have advanced Magnetorheological Finishing (MRF) techniques and tools to imprint complex continuously varying topographical structures onto large-aperture (430 x 430 mm) optical surfaces. These optics, known as continuous phase plates (CPPs), are important for high-power laser applications requiring precise manipulation and control of beam-shape, energy distribution, and wavefront profile. MRF's unique deterministic-sub-aperture polishing characteristics make it possible to imprint complex topographical information onto optical surfaces at spatial scale-lengths approaching 1 mm and surface peak-to-valleys as high as 22 {micro}m. During this discussion, we will present the evolution of the MRF imprinting technology and the MRF tools designed to manufacture large-aperture 430 x 430 mm CPPs. Our results will show how the MRF removal function impacts and limits imprint fidelity and what must be done to arrive at a high-quality surface. We also present several examples of this imprinting technology for fabrication of phase correction plates and CPPs for use in high-power laser applications.

  12. Research on 2x1 plasma electrode electro-optical switch with large aperture

    NASA Astrophysics Data System (ADS)

    Zhang, Xiong Jun; Zheng, Kui Xing; Feng, B.; Wu, D. S.; Lu, J. P.; Tian, X. L.; Jin, F.; Sui, Zhan; Wei, Xiaofeng; Zhang, Xiaomin

    2005-01-01

    In conceptual design of the prototype for SG-III facility, a full aperture electro-optical switch was placed between the cavity mirror and the main amplifier to isolate the reflected beams. The beam on the cavity mirror is 240mm×240mm square. Pockells cells of conversional design with coaxial ring electrodes can not scale to such large square aperture. In the 1980s, a plasma electrode Pockels cell (PEPC) concept was invented at LLNL. It uses transparent plasma electrode formed through gas discharge as the electrodes to apply the voltage across switching crystal to rotate the polarization of a transmitted laser beam. And it can be scaled to large aperture with thin crystal. So the switch which would be used in SG-III is based on this technology. The technical integration line as a prototype of SG-III laser is actually a 4×2 beam bundle. And the full aperture optical switch is mechanically designed four apertures as a removable unit, and electrically two 2×1 PEPC putting together. So we built a 2×1 PEPC to develop the technology first. The 2×1 PEPC is a sandwich structure made of an insulating mid plane between a pair of plasma chambers. The frame of both plasma chambers are machining in duralumin. Each chamber is installed with a planar magnetic cathode and four segments spherical anodes made from stainless steel. The cathode and anode are insulated from the housing with a special shell made from plastic, and plasma is insulated from the housing by an 80-μm-thick anodic coating on the duralumin. The two plasma chambers are separated by a mid plane of glass frame with two square holes. The two holes are filled by two electro-optical crystals with a 240-mm square aperture. With the optimized operating pressure and the electrical parameters, a very good homogeneity and low resistivity plasma electrode is obtained. Finally we tested its switching performance to simulate the case that it will be used in the SG-III prototype facility. It works with a quarter wave

  13. Pulse power requirements for large aperture optical switches based on plasma electrode Pockels cells

    SciTech Connect

    Rhodes, M.A.; Taylor, J.

    1992-06-01

    We discuss very large-aperture optical switches (greater than 30 [times] 30 cm) as an enabling technology for inertial confinement fusion drivers based on multipass laser amplifiers. Large-scale laser fusion drivers such as the Nova laser have been based on single-pass amplifier designs in part because of the unavailability of a suitable large-aperture switch. We are developing an optical switch based on a Pockels cell employing plasma-electrodes. A plasma-electrode Pockels cell (PEPC) is a longitudinal-mode Pockels cell in which a plasma discharge is formed on each side of an electro-optic crystal (typically KDP or deuterated KDP, often designated KD*P). The plasmas formed on either side of the crystal act as transparent electrodes for a switching-pulse and are intended to allow uniform charging of the entire crystal. The switching-pulse is a nominally rectangular high-voltage pulse equal to the half-wave voltage V[sub x] ( 8 kV for KD*P or 17 kV for KDP) and is applied across the crystal via the plasma-electrodes. When the crystal is charged to V[sub x], the polarization of an incoming, linearly polarized, laser beam is rotated by 90[degree]. When used in conjunction with an appropriate, passive polarizer, an optical switch is thus realized. A switch with a clear aperture of 37 [times] 37 cm is now in construction for the Beamlet laser which will serve as a test bed for this switch as well as other technologies required for an advanced NOVA laser design. In this paper, we discuss the unique power electronics requirements of PEPC optical switches.

  14. Pulse power requirements for large aperture optical switches based on plasma electrode Pockels cells

    SciTech Connect

    Rhodes, M.A.; Taylor, J.

    1992-06-01

    We discuss very large-aperture optical switches (greater than 30 {times} 30 cm) as an enabling technology for inertial confinement fusion drivers based on multipass laser amplifiers. Large-scale laser fusion drivers such as the Nova laser have been based on single-pass amplifier designs in part because of the unavailability of a suitable large-aperture switch. We are developing an optical switch based on a Pockels cell employing plasma-electrodes. A plasma-electrode Pockels cell (PEPC) is a longitudinal-mode Pockels cell in which a plasma discharge is formed on each side of an electro-optic crystal (typically KDP or deuterated KDP, often designated KD*P). The plasmas formed on either side of the crystal act as transparent electrodes for a switching-pulse and are intended to allow uniform charging of the entire crystal. The switching-pulse is a nominally rectangular high-voltage pulse equal to the half-wave voltage V{sub x} ( 8 kV for KD*P or 17 kV for KDP) and is applied across the crystal via the plasma-electrodes. When the crystal is charged to V{sub x}, the polarization of an incoming, linearly polarized, laser beam is rotated by 90{degree}. When used in conjunction with an appropriate, passive polarizer, an optical switch is thus realized. A switch with a clear aperture of 37 {times} 37 cm is now in construction for the Beamlet laser which will serve as a test bed for this switch as well as other technologies required for an advanced NOVA laser design. In this paper, we discuss the unique power electronics requirements of PEPC optical switches.

  15. Path-Average Rainfall Estimation From Optical Extinction Measurements Using a Large- Aperture Scintillometer

    NASA Astrophysics Data System (ADS)

    Uijlenhoet, R.; Cohard, J.; Gosset, M.

    2008-12-01

    We employ a Scintec BLS900 near infrared (880 nm) large aperture boundary layer scintillometer as path average rain gauge. The instrument was installed over a path of 2.4 km in Benin as part of the AMMA CATCH (African Monsoon Multidisciplinary Analysis) intensive observation period during 2006 and 2007. Measurements of the one minute average and variance of the received signal intensity from two transmitter disks of 462 LEDs each, operating at a pulse repetition rate of 5 Hz (i.e. 300 samples per minute), were collected for a few rainfall events that occurred during the dry season and several events during the wet season. Using estimates of the signal base level just before the start of the rain events, the optical extinction coefficient was estimated from the path integrated signal attenuation for each minute. The corresponding one minute path average rain rates were computed using a power law relation between the optical extinction coefficient and rain rate obtained from measurements of raindrop size spectra with an optical spectropluviometer. The estimated rain rates are compared to measurements from nearby rain gauges. Our results demonstrate the potential of optical extinction measurements from large aperture boundary layer scintillometers to obtain estimates of rainfall variability at high temporal resolution for hydrologically relevant spatial scales.

  16. A low-cost large-aperture optical receiver for remote sensing and imaging applications

    NASA Astrophysics Data System (ADS)

    Hanes, Stephen A.

    2003-03-01

    An inexpensive large aperture (10 m class) receiver for optical wavelength imaging and remote sensing applications is discussed. The design was developed for active (laser illumination) imaging of remote objects using pupil plane measurement techniques, where relatively low optical quality collecting elements can be used. The approach is also well suited for conventional imaging at lower resolutions when light collection capability is of primary importance. The approach relies on a large aperture heliostat consisting of an array of flat mirror segments, like those used in solar collector systems, to collect light from the region of interest. The heliostat segments are tilted in a manner to concentrate the light, by making the light from all segments overlap at a common point, resulting in a region of higher intensity about the size of a segment at the heliostat "focus". A smaller secondary collector, consisting of a concave mirror located at the overlap point, further concentrates the light and forms a pupil image of the heliostat. Additional optics near the pupil image collimate the light for efficient transmission though a narrow band interference filter used to reduce sky background, and focus the light onto a PMT, or other sensor, for detection. Several design approaches for the collimating optics are discussed as well as system performance and limitations.

  17. End-to-End Assessment of a Large Aperture Segmented Ultraviolet Optical Infrared (UVOIR) Telescope Architecture

    NASA Technical Reports Server (NTRS)

    Feinberg, Lee; Rioux, Norman; Bolcar, Matthew; Liu, Alice; Guyon, Oliver; Stark, Chris; Arenberg, Jon

    2016-01-01

    Key challenges of a future large aperture, segmented Ultraviolet Optical Infrared (UVOIR) Telescope capable of performing a spectroscopic survey of hundreds of Exoplanets will be sufficient stability to achieve 10^-10 contrast measurements and sufficient throughput and sensitivity for high yield Exo-Earth spectroscopic detection. Our team has collectively assessed an optimized end to end architecture including a high throughput coronagraph capable of working with a segmented telescope, a cost-effective and heritage based stable segmented telescope, a control architecture that minimizes the amount of new technologies, and an Exo-Earth yield assessment to evaluate potential performance. These efforts are combined through integrated modeling, coronagraph evaluations, and Exo-Earth yield calculations to assess the potential performance of the selected architecture. In addition, we discusses the scalability of this architecture to larger apertures and the technological tall poles to enabling it.

  18. End-to-end assessment of a large aperture segmented ultraviolet optical infrared (UVOIR) telescope architecture

    NASA Astrophysics Data System (ADS)

    Feinberg, Lee; Rioux, Norman; Bolcar, Matthew; Liu, Alice; Guyon, Olivier; Stark, Chris; Arenberg, Jon

    2016-07-01

    Key challenges of a future large aperture, segmented Ultraviolet Optical Infrared (UVOIR) Telescope capable of performing a spectroscopic survey of hundreds of Exoplanets will be sufficient stability to achieve 10^-10 contrast measurements and sufficient throughput and sensitivity for high yield exo-earth spectroscopic detection. Our team has collectively assessed an optimized end to end architecture including a high throughput coronagraph capable of working with a segmented telescope, a cost-effective and heritage based stable segmented telescope, a control architecture that minimizes the amount of new technologies, and an exo-earth yield assessment to evaluate potential performance. These efforts are combined through integrated modeling, coronagraph evaluations, and exo-earth yield calculations to assess the potential performance of the selected architecture. In addition, we discusses the scalability of this architecture to larger apertures and the technological tall poles to enabling these missions.

  19. End-to-End Assessment of a Large Aperture Segmented Ultraviolet Optical Infrared (UVOIR) Telescope Architecture

    NASA Technical Reports Server (NTRS)

    Feinberg, Lee; Bolcar, Matt; Liu, Alice; Guyon, Olivier; Stark,Chris; Arenberg, Jon

    2016-01-01

    Key challenges of a future large aperture, segmented Ultraviolet Optical Infrared (UVOIR) Telescope capable of performing a spectroscopic survey of hundreds of Exoplanets will be sufficient stability to achieve 10-10 contrast measurements and sufficient throughput and sensitivity for high yield Exo-Earth spectroscopic detection. Our team has collectively assessed an optimized end to end architecture including a high throughput coronagraph capable of working with a segmented telescope, a cost-effective and heritage based stable segmented telescope, a control architecture that minimizes the amount of new technologies, and an Exo-Earth yield assessment to evaluate potential performance.

  20. In-situ monitoring of surface post-processing in large aperture fused silica optics with Optical Coherence Tomography

    SciTech Connect

    Guss, G M; Bass, I l; Hackel, R P; Mailhiot, C; Demos, S G

    2008-02-08

    Optical Coherence Tomography is explored as a method to image laser-damage sites located on the surface of large aperture fused silica optics during post-processing via CO{sub 2} laser ablation. The signal analysis for image acquisition was adapted to meet the sensitivity requirements for this application. A long-working distance geometry was employed to allow imaging through the opposite surface of the 5-cm thick optic. The experimental results demonstrate the potential of OCT for remote monitoring of transparent material processing applications.

  1. Horizon: A Proposal for Large Aperture, Active Optics in Geosynchronous Orbit

    NASA Technical Reports Server (NTRS)

    Chesters, Dennis; Jenstrom, Del

    2000-01-01

    In 1999, NASA's New Millennium Program called for proposals to validate new technology in high-earth orbit for the Earth Observing-3 (NMP EO3) mission to fly in 2003. In response, we proposed to test a large aperture, active optics telescope in geosynchronous orbit. This would flight-qualify new technologies for both Earth and Space science: 1) a future instrument with LANDSAT image resolution and radiometric quality watching continuously from geosynchronous station, and 2) the Next Generation Space Telescope (NGST) for deep space imaging. Six enabling technologies were to be flight-qualified: 1) a 3-meter, lightweight segmented primary mirror, 2) mirror actuators and mechanisms, 3) a deformable mirror, 4) coarse phasing techniques, 5) phase retrieval for wavefront control during stellar viewing, and 6) phase diversity for wavefront control during Earth viewing. Three enhancing technologies were to be flight- validated: 1) mirror deployment and latching mechanisms, 2) an advanced microcontroller, and 3) GPS at GEO. In particular, two wavefront sensing algorithms, phase retrieval by JPL and phase diversity by ERIM International, were to sense optical system alignment and focus errors, and to correct them using high-precision mirror mechanisms. Active corrections based on Earth scenes are challenging because phase diversity images must be collected from extended, dynamically changing scenes. In addition, an Earth-facing telescope in GEO orbit is subject to a powerful diurnal thermal and radiometric cycle not experienced by deep-space astronomy. The Horizon proposal was a bare-bones design for a lightweight large-aperture, active optical system that is a practical blend of science requirements, emerging technologies, budget constraints, launch vehicle considerations, orbital mechanics, optical hardware, phase-determination algorithms, communication strategy, computational burdens, and first-rate cooperation among earth and space scientists, engineers and managers

  2. Switch-zoom optical system design of large aperture ground-based photoelectric detection

    NASA Astrophysics Data System (ADS)

    Yan, Peipei; Liu, Kai; Duan, Jing; Jiang, Kai; Shan, Qiusha

    2016-10-01

    Binary optics can be used to increase optical performances, decrease size and weight, and decrease systems costs in numerous applications. By means of hybrid diffractive-refractive, a switch-zoom optical system of catadioptric large aperture ground-based photoelectric detection is designed. The characteristic of the system is that it is a compact optical system without moving parts which can get two focal lengths. And the quality of image approaches the diffraction limited. Ritchey-Chrétien (R-C) mirror and a field lens are common for long-focus system and short-focus system. Two refract groups transmitting optical system are used for zooming. In order to satisfy the demand of energy regulation, it is designed afocal beam between field lens and later refract optical system. Filter and variable density plate are placed in it to guarantee the imaging quality. The focal length is 3750mm and F number is 7.5 for the long-focus system, and the focal length is 1850mm and F number is 3.75 for the short-focus system. Former part and later lens of the system are both perfect imaging. They can be fabricated and detected independently. So the design demand can be satisfied better and the imaging quality can be improved.

  3. Path-average rainfall estimation from optical extinction measurements using a large-aperture scintillometer

    NASA Astrophysics Data System (ADS)

    Uijlenhoet, Remko; Cohard, Jean-Martial; Gosset, Marielle

    2010-05-01

    The potential of a near infrared large-aperture boundary layer scintillometer as path-average rain gauge is investigated. The instrument was installed over a 2.4 km path in Benin as part of the AMMA Enhanced Observation Period during 2006 and 2007. Measurements of the one-minute average received signal intensity were collected for 6 rainfall events during the dry season and 16 events during the wet season. Using estimates of the signal base level just before the onset of the rain events, the optical extinction coeffcient is estimated from the path-integrated attenuation for each minute. The corresponding path-average rain rates are computed using a power-law relation between the optical extinction coeffcient and rain rate obtained from measurements of raindrop size distributions with an optical spectropluviometer. Comparisons of five-minute rainfall estimates with measurements from two nearby rain gauges show that the temporal dynamics are generally captured well by the scintillometer. However, the instrument has a tendency to underestimate rain rates and event total rain amounts with respect to the gauges. It is shown that this underestimation can be explained partly by systematic differences between the actual and the employed mean power-law relation between rain rate and specific attenuation, partly by unresolved spatial and temporal rainfall variations along the scintillometer path. Occasionally, the signal may even be lost completely. It is demonstrated that if these effects are properly accounted for, by employing appropriate relations between rain rate and specific attenuation and by adapting the path length to the local rainfall climatology, scintillometer-based rainfall estimates can be within 20% of those estimated using rain gauges. These results demonstrate the potential of large-aperture scintillometers to estimate path-average rain rates at hydrologically relevant scales.

  4. Bragg reflectors for large optical aperture MEMS Fabry-Perot interferometers

    NASA Astrophysics Data System (ADS)

    Rissanen, Anna; Mannila, Rami; Antila, Jarkko

    2012-06-01

    This paper presents the fabrication of large-aperture low-pressure chemical-vapour deposited (LPCVD) Bragg reflectors utilizing low-stress polysilicon (PolySi) and silicon-rich silicon nitride (SiN) λ/4-thin film stacks. These structures can function as the upper mirror in a MEMS FPI device. High aspect-ratio mirror membranes were successfully released for 5 - 10 mm diameter range by sacrificial SiO2 etching in HF vapour. Optical simulations are presented for the Bragg reflector test structures designed for FPIs operating in the NIR range and the properties such as release yield and mechanical stability of the released LPCVD deposited polySi-SiN mirror membranes are compared with similar released atomic layer deposited (ALD) Al2O3-TiO2 λ/4-thin film mirror stacks. The realization of these Bragg reflector structures is the first step in the process integration of large-aperture MEMS FPI for miniature NIR imaging spectrometers, which can be applied to a variety of applications ranging from medical imaging and diagnostics to spaceand environmental monitoring instrumentation.

  5. Large aperture diffractive space telescope

    DOEpatents

    Hyde, Roderick A.

    2001-01-01

    A large (10's of meters) aperture space telescope including two separate spacecraft--an optical primary objective lens functioning as a magnifying glass and an optical secondary functioning as an eyepiece. The spacecraft are spaced up to several kilometers apart with the eyepiece directly behind the magnifying glass "aiming" at an intended target with their relative orientation determining the optical axis of the telescope and hence the targets being observed. The objective lens includes a very large-aperture, very-thin-membrane, diffractive lens, e.g., a Fresnel lens, which intercepts incoming light over its full aperture and focuses it towards the eyepiece. The eyepiece has a much smaller, meter-scale aperture and is designed to move along the focal surface of the objective lens, gathering up the incoming light and converting it to high quality images. The positions of the two space craft are controlled both to maintain a good optical focus and to point at desired targets which may be either earth bound or celestial.

  6. Improving 351-nm Damage Performance of Large-Aperture Fused Silica and DKDP Optics

    SciTech Connect

    Burnham, A K; Hackel, L; Wegner, P; Parham, T; Hrubesh, L; Penetrante, B; Whitman, P; Demos, S; Menapace, J; Runkel, M; Fluss, M; Feit, M; Key, M; Biesiada, T

    2002-01-07

    A program to identify and eliminate the causes of UV laser-induced damage and growth in fused silica and DKDP has developed methods to extend optics lifetimes for large-aperture, high-peak-power, UV lasers such as the National Ignition Facility (NIF). Issues included polish-related surface damage initiation and growth on fused silica and DKDP, bulk inclusions in fused silica, pinpoint bulk damage in DKDP, and UV-induced surface degradation in fused silica and DKDP in a vacuum. Approaches included an understanding of the mechanism of the damage, incremental improvements to existing fabrication technology, and feasibility studies of non-traditional fabrication technologies. Status and success of these various approaches are reviewed. Improvements were made in reducing surface damage initiation and eliminating growth for fused silica by improved polishing and post-processing steps, and improved analytical techniques are providing insights into mechanisms of DKDP damage. The NIF final optics hardware has been designed to enable easy retrieval, surface-damage mitigation, and recycling of optics.

  7. The measurement and analysis of wavefront structure from large aperture ICF optics

    SciTech Connect

    Wolfe, C.R.; Lawson, J.K.

    1995-05-30

    This paper discusses the techniques, developed over the past year, for high spatial resolution measurement and analysis of the transmitted and/or reflected wavefront of large aperture ICF optical components. Parts up to 400 mm {times} 750 mm have been measured and include: laser slabs, windows, KDP crystals and lenses. The measurements were performed using state-of-the-art commercial phase shifting interferometers at a wavelength of 633 {mu}m. Both 1 and 2-D Fourier analysis have been used to characterize the wavefront; specifically the Power Spectral Density, (PSD), function was calculated. The PSDs of several precision optical components will be shown. The PSD(V) is proportional to the (amplitude){sup 2} of components of the Fourier frequency spectrum. The PSD describes the scattered intensity and direction as a function of scattering angle in the wavefront. The capability of commercial software is limited to 1-D Fourier analysis only. We are developing our own 2-D analysis capability in support of work to revise specifications for NIF optics. 2-D analysis uses the entire wavefront phase map to construct 2D PSD functions. We have been able to increase the signal-to-noise relative to 1-D and can observe very subtle wavefront structure.

  8. Structural Feasibility Analysis of a Robotically Assembled Very Large Aperture Optical Space Telescope

    NASA Technical Reports Server (NTRS)

    Wilkie, William Keats; Williams, R. Brett; Agnes, Gregory S.; Wilcox, Brian H.

    2007-01-01

    This paper presents a feasibility study of robotically constructing a very large aperture optical space telescope on-orbit. Since the largest engineering challenges are likely to reside in the design and assembly of the 150-m diameter primary reflector, this preliminary study focuses on this component. The same technology developed for construction of the primary would then be readily used for the smaller optical structures (secondary, tertiary, etc.). A reasonable set of ground and on-orbit loading scenarios are compiled from the literature and used to define the structural performance requirements and size the primary reflector. A surface precision analysis shows that active adjustment of the primary structure is required in order to meet stringent optical surface requirements. Two potential actuation strategies are discussed along with potential actuation devices at the current state of the art. The finding of this research effort indicate that successful technology development combined with further analysis will likely enable such a telescope to be built in the future.

  9. Structural Feasibility Analysis of a Robotically Assembled Very Large Aperture Optical Space Telescope

    NASA Technical Reports Server (NTRS)

    Wilkie, William Keats; Williams, R. Brett; Agnes, Gregory S.; Wilcox, Brian H.

    2007-01-01

    This paper presents a feasibility study of robotically constructing a very large aperture optical space telescope on-orbit. Since the largest engineering challenges are likely to reside in the design and assembly of the 150-m diameter primary reflector, this preliminary study focuses on this component. The same technology developed for construction of the primary would then be readily used for the smaller optical structures (secondary, tertiary, etc.). A reasonable set of ground and on-orbit loading scenarios are compiled from the literature and used to define the structural performance requirements and size the primary reflector. A surface precision analysis shows that active adjustment of the primary structure is required in order to meet stringent optical surface requirements. Two potential actuation strategies are discussed along with potential actuation devices at the current state of the art. The finding of this research effort indicate that successful technology development combined with further analysis will likely enable such a telescope to be built in the future.

  10. A method on error analysis for large-aperture optical telescope control system

    NASA Astrophysics Data System (ADS)

    Su, Yanrui; Wang, Qiang; Yan, Fabao; Liu, Xiang; Huang, Yongmei

    2016-10-01

    For large-aperture optical telescope, compared with the performance of azimuth in the control system, arc second-level jitters exist in elevation under different speeds' working mode, especially low-speed working mode in the process of its acquisition, tracking and pointing. The jitters are closely related to the working speed of the elevation, resulting in the reduction of accuracy and low-speed stability of the telescope. By collecting a large number of measured data to the elevation, we do analysis on jitters in the time domain, frequency domain and space domain respectively. And the relation between jitter points and the leading speed of elevation and the corresponding space angle is concluded that the jitters perform as periodic disturbance in space domain and the period of the corresponding space angle of the jitter points is 79.1″ approximately. Then we did simulation, analysis and comparison to the influence of the disturbance sources, like PWM power level output disturbance, torque (acceleration) disturbance, speed feedback disturbance and position feedback disturbance on the elevation to find that the space periodic disturbance still exist in the elevation performance. It leads us to infer that the problems maybe exist in angle measurement unit. The telescope employs a 24-bit photoelectric encoder and we can calculate the encoder grating angular resolution as 79.1016'', which is as the corresponding angle value in the whole encoder system of one period of the subdivision signal. The value is approximately equal to the space frequency of the jitters. Therefore, the working elevation of the telescope is affected by subdivision errors and the period of the subdivision error is identical to the period of encoder grating angular. Through comprehensive consideration and mathematical analysis, that DC subdivision error of subdivision error sources causes the jitters is determined, which is verified in the practical engineering. The method that analyze error

  11. Measurement and analysis of wavefront structure from large-aperture ICF optics

    NASA Astrophysics Data System (ADS)

    Wolfe, C. Robert; Lawson, Janice K.

    1995-12-01

    This paper discusses the techniques, developed over the past year, for high spatial resolution measurement and analysis of the transmitted and/or reflected wavefront of large aperture ICF optical components. Parts up to 400 mm by 750 mm have been measured and include: laser slabs, windows, KDP crystals and lenses. The measurements were performed using state-of- the-art commercial phase shifting interferometers at a wavelength of 633 micrometer. Both 1 and 2-D Fourier analysis have been used to characterize the wavefront; specifically the power spectral density (PSD) function was calculated. The PSDs of several precision optical components are shown. The PSD(nu) is proportional to the (amplitude)2 of components of the Fourier frequency spectrum. The PSD describes the scattered intensity and direction as a function of scattering angle in the wavefront. The capability of commercial software is limited to 1-D Fourier analysis only. We are developing our own 2-D analysis capability in support of work to revise specifications for NIF optics. Two-dimensional analysis uses the entire wavefront phase map to construct 2-D PSD functions. We have been able to increase the signal-to-noise relative to 1-D and can observe very subtle wavefront structure. The physics of the NIF laser design dictate partitioning the wavefront into three regimes of spatial wavelength (or spatial frequency). We discuss the data in terms of the following three scale length regimes: (1) short scale, or 'micro roughness,' having scale lengths less than 120 micrometer; (2) mid-spatial scale, with scale lengths from 0.12 to 33 mm; and (3) long scale, or conventional 'optical figure/curvature,' having scale lengths greater than 33 mm. Regular repetitive wavefront structure has been observed in all three regimes, ranging from 10 micrometer to 100 mm in scale length. The magnitude of these structures are typically from lambda/100 to lambda/20. Structure has been detected in optical materials and on the

  12. Developing Magnetorheological Finishing (MRF) Technology for the Manufacture of Large-Aperture Optics in Megajoule Class Laser Systems

    SciTech Connect

    Menapace, J A

    2010-10-27

    Over the last eight years we have been developing advanced MRF tools and techniques to manufacture meter-scale optics for use in Megajoule class laser systems. These systems call for optics having unique characteristics that can complicate their fabrication using conventional polishing methods. First, exposure to the high-power nanosecond and sub-nanosecond pulsed laser environment in the infrared (>27 J/cm{sup 2} at 1053 nm), visible (>18 J/cm{sup 2} at 527 nm), and ultraviolet (>10 J/cm{sup 2} at 351 nm) demands ultra-precise control of optical figure and finish to avoid intensity modulation and scatter that can result in damage to the optics chain or system hardware. Second, the optics must be super-polished and virtually free of surface and subsurface flaws that can limit optic lifetime through laser-induced damage initiation and growth at the flaw sites, particularly at 351 nm. Lastly, ultra-precise optics for beam conditioning are required to control laser beam quality. These optics contain customized surface topographical structures that cannot be made using traditional fabrication processes. In this review, we will present the development and implementation of large-aperture MRF tools and techniques specifically designed to meet the demanding optical performance challenges required in large-aperture high-power laser systems. In particular, we will discuss the advances made by using MRF technology to expose and remove surface and subsurface flaws in optics during final polishing to yield optics with improve laser damage resistance, the novel application of MRF deterministic polishing to imprint complex topographical information and wavefront correction patterns onto optical surfaces, and our efforts to advance the technology to manufacture large-aperture damage resistant optics.

  13. Large Aperture Scintillometer Intercomparison Study

    NASA Astrophysics Data System (ADS)

    Kleissl, J.; Gomez, J.; Hong, S.-H.; Hendrickx, J. M. H.; Rahn, T.; Defoor, W. L.

    2008-07-01

    Two field studies with six large aperture scintillometers (LASs) were performed using horizontal and slant paths. The accuracy of this novel and increasingly popular technique for measuring sensible heat fluxes was quantified by comparing measurements from different instruments over nearly identical transects. Random errors in LAS measurements were small, since correlation coefficients between adjacent measurements were greater than 0.995. However, for an ideal set-up differences in linear regression slopes of up to 21% were observed with typical inter-instrument differences of 6%. Differences of 10% are typical in more realistic measurement scenarios over homogeneous natural vegetation and different transect heights and locations. Inaccuracies in the optics, which affect the effective aperture diameter, are the most likely explanation for the observed differences.

  14. A very large aperture spectrometer for low light optical emission spectroscopy

    NASA Astrophysics Data System (ADS)

    Baude, R.; Escarguel, A.; David, P.

    2017-02-01

    In low light experiments such as low temperature plasma or astronomical spectroscopy usual tools such as Czerny Turner based spectrometer (CTS) may have a limited efficiency due to the fact that a large entrance slit implies a large broadening of the instruments profile. To overcome the brightness issue of spectrometer, the so-called Bowen Chamber spectrometer (BCS) was designed to accept a large aperture slit, without significant deterioration of the spectrum. The BSC characteristics are presented and a close comparison with a CTS spectrometer is detailed. A simple geometrical model have been developed to still improve the BSC specifications.

  15. Very Large Aperture Diffractive Space Telescope

    SciTech Connect

    Hyde, Roderick Allen

    1998-04-20

    A very large (10's of meters) aperture space telescope including two separate spacecraft--an optical primary functioning as a magnifying glass and an optical secondary functioning as an eyepiece. The spacecraft are spaced up to several kilometers apart with the eyepiece directly behind the magnifying glass ''aiming'' at an intended target with their relative orientation determining the optical axis of the telescope and hence the targets being observed. The magnifying glass includes a very large-aperture, very-thin-membrane, diffractive lens, e.g., a Fresnel lens, which intercepts incoming light over its full aperture and focuses it towards the eyepiece. The eyepiece has a much smaller, meter-scale aperture and is designed to move along the focal surface of the magnifying glass, gathering up the incoming light and converting it to high quality images. The positions of the two space craft are controlled both to maintain a good optical focus and to point at desired targets.

  16. Large aperture Fresnel telescopes/011

    SciTech Connect

    Hyde, R.A., LLNL

    1998-07-16

    At Livermore we`ve spent the last two years examining an alternative approach towards very large aperture (VLA) telescopes, one based upon transmissive Fresnel lenses rather than on mirrors. Fresnel lenses are attractive for VLA telescopes because they are launchable (lightweight, packagable, and deployable) and because they virtually eliminate the traditional, very tight, surface shape requirements faced by reflecting telescopes. Their (potentially severe) optical drawback, a very narrow spectral bandwidth, can be eliminated by use of a second (much smaller) chromatically-correcting Fresnel element. This enables Fresnel VLA telescopes to provide either single band ({Delta}{lambda}/{lambda} {approximately} 0.1), multiple band, or continuous spectral coverage. Building and fielding such large Fresnel lenses will present a significant challenge, but one which appears, with effort, to be solvable.

  17. Eyeglass. 1. Very large aperture diffractive telescopes

    SciTech Connect

    Hyde, R.A.

    1999-07-01

    The Eyeglass is a very large aperture (25{endash}100-m) space telescope consisting of two distinct spacecraft, separated in space by several kilometers. A diffractive lens provides the telescope{close_quote}s large aperture, and a separate, much smaller, space telescope serves as its mobile eyepiece. Use of a transmissive diffractive lens solves two basic problems associated with very large aperture space telescopes; it is inherently launchable (lightweight, packagable, and deployable) it and virtually eliminates the traditional, very tight surface shape tolerances faced by reflecting apertures. The potential drawback to use of a diffractive primary (very narrow spectral bandwidth) is eliminated by corrective optics in the telescope{close_quote}s eyepiece; the Eyeglass can provide diffraction-limited imaging with either single-band ({Delta}{lambda}/{lambda}{approximately}0.1), multiband, or continuous spectral coverage. {copyright} 1999 Optical Society of America

  18. Visible light high-resolution imaging system for large aperture telescope by liquid crystal adaptive optics with phase diversity technique.

    PubMed

    Xu, Zihao; Yang, Chengliang; Zhang, Peiguang; Zhang, Xingyun; Cao, Zhaoliang; Mu, Quanquan; Sun, Qiang; Xuan, Li

    2017-08-30

    There are more than eight large aperture telescopes (larger than eight meters) equipped with adaptive optics system in the world until now. Due to the limitations such as the difficulties of increasing actuator number of deformable mirror, most of them work in the infrared waveband. A novel two-step high-resolution optical imaging approach is proposed by applying phase diversity (PD) technique to the open-loop liquid crystal adaptive optics system (LC AOS) for visible light high-resolution adaptive imaging. Considering the traditional PD is not suitable for LC AOS, the novel PD strategy is proposed which can reduce the wavefront estimating error caused by non-modulated light generated by liquid crystal spatial light modulator (LC SLM) and make the residual distortions after open-loop correction to be smaller. Moreover, the LC SLM can introduce any aberration which realizes the free selection of phase diversity. The estimating errors are greatly reduced in both simulations and experiments. The resolution of the reconstructed image is greatly improved on both subjective visual effect and the highest discernible space resolution. Such technique can be widely used in large aperture telescopes for astronomical observations such as terrestrial planets, quasars and also can be used in other applications related to wavefront correction.

  19. DM/LCWFC based adaptive optics system for large aperture telescopes imaging from visible to infrared waveband.

    PubMed

    Sun, Fei; Cao, Zhaoliang; Wang, Yukun; Zhang, Caihua; Zhang, Xingyun; Liu, Yong; Mu, Quanquan; Xuan, Li

    2016-11-28

    Almost all the deformable mirror (DM) based adaptive optics systems (AOSs) used on large aperture telescopes work at the infrared waveband due to the limitation of the number of actuators. To extend the imaging waveband to the visible, we propose a DM and Liquid crystal wavefront corrector (DM/LCWFC) combination AOS. The LCWFC is used to correct the high frequency aberration corresponding to the visible waveband and the aberrations of the infrared are corrected by the DM. The calculated results show that, to a 10 m telescope, DM/LCWFC AOS which contains a 1538 actuators DM and a 404 × 404 pixels LCWFC is equivalent to a DM based AOS with 4057 actuators. It indicates that the DM/LCWFC AOS is possible to work from visible to infrared for larger aperture telescopes. The simulations and laboratory experiment are performed for a 2 m telescope. The experimental results show that, after correction, near diffraction limited resolution USAF target images are obtained at the wavebands of 0.7-0.9 μm, 0.9-1.5 μm and 1.5-1.7 μm respectively. Therefore, the DM/LCWFC AOS may be used to extend imaging waveband of larger aperture telescope to the visible. It is very appropriate for the observation of spatial objects and the scientific research in astronomy.

  20. Differential Optical Synthetic Aperture Radar

    DOEpatents

    Stappaerts, Eddy A.

    2005-04-12

    A new differential technique for forming optical images using a synthetic aperture is introduced. This differential technique utilizes a single aperture to obtain unique (N) phases that can be processed to produce a synthetic aperture image at points along a trajectory. This is accomplished by dividing the aperture into two equal "subapertures", each having a width that is less than the actual aperture, along the direction of flight. As the platform flies along a given trajectory, a source illuminates objects and the two subapertures are configured to collect return signals. The techniques of the invention is designed to cancel common-mode errors, trajectory deviations from a straight line, and laser phase noise to provide the set of resultant (N) phases that can produce an image having a spatial resolution corresponding to a synthetic aperture.

  1. Eyeglass. 1. Very large aperture diffractive telescopes.

    PubMed

    Hyde, R A

    1999-07-01

    The Eyeglass is a very large aperture (25-100-m) space telescope consisting of two distinct spacecraft, separated in space by several kilometers. A diffractive lens provides the telescope s large aperture, and a separate, much smaller, space telescope serves as its mobile eyepiece. Use of a transmissive diffractive lens solves two basic problems associated with very large aperture space telescopes; it is inherently launchable (lightweight, packagable, and deployable) it and virtually eliminates the traditional, very tight surface shape tolerances faced by reflecting apertures. The potential drawback to use of a diffractive primary (very narrow spectral bandwidth) is eliminated by corrective optics in the telescope s eyepiece; the Eyeglass can provide diffraction-limited imaging with either single-band (Deltalambda/lambda approximately 0.1), multiband, or continuous spectral coverage.

  2. Performance Evaluation of Large Aperture 'Polished Panel' Optical Receivers Based on Experimental Data

    NASA Technical Reports Server (NTRS)

    Vilnrotter, Victor

    2013-01-01

    Recent interest in hybrid RF/Optical communications has led to the development and installation of a "polished-panel" optical receiver evaluation assembly on the 34-meter research antenna at Deep-Space Station 13 (DSS-13) at NASA's Goldstone Communications Complex. The test setup consists of a custom aluminum panel polished to optical smoothness, and a large-sensor CCD camera designed to image the point-spread function (PSF) generated by the polished aluminum panel. Extensive data has been obtained via realtime tracking and imaging of planets and stars at DSS-13. Both "on-source" and "off-source" data were recorded at various elevations, enabling the development of realistic simulations and analytic models to help determine the performance of future deep-space communications systems operating with on-off keying (OOK) or pulse-position-modulated (PPM) signaling formats with photon-counting detection, and compared with the ultimate quantum bound on detection performance for these modulations. Experimentally determined PSFs were scaled to provide realistic signal-distributions across a photon-counting detector array when a pulse is received, and uncoded as well as block-coded performance analyzed and evaluated for a well-known class of block codes.

  3. Performance evaluation of large aperture "polished panel" optical receivers based on experimental data

    NASA Astrophysics Data System (ADS)

    Vilnrotter, V.

    Recent interest in the development of hybrid RF/Optical communications has led to the installation of a “ polished-panel” optical receiver evaluation assembly on the 34-meter research antenna at Deep-Space Station 13 (DSS-13) at NASA's Goldstone Deep Space Communications Complex1. The test setup consists of a custom aluminum panel polished to optical smoothness, and a large-sensor CCD camera designed to image the point-spread function (PSF) generated by the polished aluminum panel. Extensive data has been obtained via real-time tracking and imaging of planets and stars at DSS-13. Both “ on-source” and “ off-source” data were recorded at various elevations, enabling the development of realistic simulations and analytic models to help determine the performance of future deep-space communications systems operating with on-off keying (OOK) or pulse-position-modulated (PPM) signaling formats, and compared with the ultimate quantum bound on detection performance. Experimentally determined PSFs were scaled to provide realistic signal-distributions across a photon-counting detector array when a pulse is received, and uncoded as well as block-coded performance analyzed and evaluated for a well-known class of block codes.

  4. Performance Evaluation of Large Aperture 'Polished Panel' Optical Receivers Based on Experimental Data

    NASA Technical Reports Server (NTRS)

    Vilnrotter, Victor

    2013-01-01

    Recent interest in hybrid RF/Optical communications has led to the development and installation of a "polished-panel" optical receiver evaluation assembly on the 34-meter research antenna at Deep-Space Station 13 (DSS-13) at NASA's Goldstone Communications Complex. The test setup consists of a custom aluminum panel polished to optical smoothness, and a large-sensor CCD camera designed to image the point-spread function (PSF) generated by the polished aluminum panel. Extensive data has been obtained via realtime tracking and imaging of planets and stars at DSS-13. Both "on-source" and "off-source" data were recorded at various elevations, enabling the development of realistic simulations and analytic models to help determine the performance of future deep-space communications systems operating with on-off keying (OOK) or pulse-position-modulated (PPM) signaling formats with photon-counting detection, and compared with the ultimate quantum bound on detection performance for these modulations. Experimentally determined PSFs were scaled to provide realistic signal-distributions across a photon-counting detector array when a pulse is received, and uncoded as well as block-coded performance analyzed and evaluated for a well-known class of block codes.

  5. Research on precision grinding processing and compensation finishing experiment for mid-large- aperture square aspheric optical element

    NASA Astrophysics Data System (ADS)

    Nie, Fengming; Li, Zhanguo; Wang, Dasen; Zhang, Guangping; Guo, Chengjun; Pei, Ning; Li, Yupeng

    2014-08-01

    This paper analyzes dot-line envelope grinding principle, which is applicable to mid-large- aperture square aspheric optical element, determines the mathematical process control model based on X/Y/C three-axis aspheric grinding machine, We develop the appropriate high-precision aspheric grinding manufacturing and measurement systems software, using the plane grinding wheel to do the grinding experiments and the repeated compensation processing experiment. The experiments show that: high-precision aspheric grinding manufacturing and measurement systems software can be realized axisymmetric aspheric high-precision machining control and measurement; using compensation processing of the X/Y/C three-axis aspheric grinding machine which can effectively improve the precision PV value, surface error from the initial processing of the PV value :12 μm to the compensation processing of the PV value :3 μm .

  6. A conceptual design for a Cassegrain-mounted high-resolution optical spectrograph for large-aperture telescopes

    NASA Astrophysics Data System (ADS)

    Froning, Cynthia S.; Osterman, Steven; Burgh, Eric; Beasley, Matthew; Scowen, Paul; Veach, Todd; Jordan, Steven; Ebbets, Dennis; Lieber, Michael; deCino, James; Castilho, Bruno Vaz; Gneiding, Clemens; César de Oliveira, Antonio

    2013-09-01

    We present a conceptual design for a high-resolution optical spectrograph appropriate for mounting at Cassegrain on a large aperture telescope. The design is based on our work for the Gemini High Resolution Optical Spectrograph (CUGHOS) project. Our design places the spectrograph at Cassegrain focus to maximize throughput and blue wavelength coverage, delivering R=40,000 resolving power over a continuous 320-1050 nm waveband with throughputs twice those of current instruments. The optical design uses a two-arm, cross-dispersed echelle format with each arm optimized to maximize efficiency. A fixed image slicer is used to minimize optics sizes. The principal challenge for the instrument design is to minimize flexure and degradation of the optical image. To ensure image stability, our opto-mechanical design combines a cost-effective, passively stable bench employing a honeycomb aluminum structure with active flexure control. The active flexure compensation consists of hexapod mounts for each focal plane with full 6-axis range of motion capability to correct for focus and beam displacement. We verified instrument performance using an integrated model that couples the optical and mechanical design to image performance. The full end-to-end modeling of the system under gravitational, thermal, and vibrational perturbations shows that deflections of the optical beam at the focal plane are <29 μm per exposure under the worst case scenario (<10 μm for most orientations), with final correction to 5 μm or better using open-loop active control to meet the stability requirement. The design elements and high fidelity modeling process are generally applicable to instruments requiring high stability under a varying gravity vector.

  7. Thermo-optical simulation and experiment for the assessment of single, hollow, and large aperture retroreflector for lunar laser ranging

    NASA Astrophysics Data System (ADS)

    Araki, Hiroshi; Kashima, Shingo; Noda, Hirotomo; Kunimori, Hiroo; Chiba, Kouta; Mashiko, Hitomi; Kato, Hiromasa; Otsubo, Toshimichi; Matsumoto, Yoshiaki; Tsuruta, Seiitsu; Asari, Kazuyoshi; Hanada, Hideo; Yasuda, Susumu; Utsunomiya, Shin; Takino, Hideo

    2016-06-01

    A single aperture and hollow retroreflector [corner-cube mirror (CCM)] that in principle has no internal optical path difference is a key instrument for achieving lunar laser ranging one order or more accurate than the current level (~2 cm). We are developing CCM whose aperture is 20 cm with optimized dihedral angles. The 20-cm CCM yields two times peak height for returned laser pulse compared with Apollo 15's retroreflector. Two investigations were conducted to confirm the feasibility of the 20-cm aperture CCM. The first is thermo-optical simulation and evaluation of the 20-cm CCM in the lunar thermal environment. Through this simulation, it has turned out for the first time that 20-cm aperture CCM made of single-crystal Si or "ultra-low expansion glass-ceramics" such as CCZ-EX® (OHARA Inc.) can be used for CCM with no thermal control, if the perfectly fixed point of CCM is limited to one. The second is annealing and shear loading experiments of single-crystal silicon (Si) samples. Through these experiments, high-temperature annealing from 100 to 1000 °C is confirmed to be effective for the enhancement of the adhesive strength between optically contacted surfaces with no optical damage in roughness and accuracy, indicating that this annealing process would enhance the rigidity of CCM fabricated by the optically contacted plates.

  8. Measurement of wavefront structure from large aperture optical components by phase shifting interferometry

    SciTech Connect

    Wolfe, C.R.; Lawson, J.K.; Kellam, M.; Maney, R.T.; Demiris, A.

    1995-05-12

    This paper discusses the results of high spatial resolution measurement of the transmitted or reflected wavefront of optical components using phase shifting interferometry with a wavelength of 6328 {angstrom}. The optical components studied range in size from approximately 50 mm {times} 100 mm to 400 mm {times} 750 mm. Wavefront data, in the form of 3-D phase maps, have been obtained for three regimes of scale length: ``micro roughness``, ``mid-spatial scale``, and ``optical figure/curvature.`` Repetitive wavefront structure has been observed with scale lengths from 10 mm to 100 mm. The amplitude of this structure is typically {lambda}/100 to {lambda}/20. Previously unobserved structure has been detected in optical materials and on the surfaces of components. We are using this data to assist in optimizing laser system design, to qualify optical components and fabrication processes under study in our component development program.

  9. Parallel optical nanolithography using nanoscale bowtie apertures

    NASA Astrophysics Data System (ADS)

    Uppuluri, Sreemanth M. V.

    needed to bring an array of bowtie apertures into intimate contact with the photoresist surface we present an optical interference based alignment system that aligns the mask and photoresist surfaces to within 0.1 mrad of parallelism. In this work we show that bowtie apertures can be used to produce patterns in the photoresist of dimensions in the order of 85-90 nm. We also demonstrate parallel optical nanolithography using an array of bowtie apertures that opens up the possibility of using arrays of bowtie apertures to produce a large number of nanoscale light spots for parallel nano-manufacturing.

  10. Technology development for the Advanced Technology Large Aperture Space Telescope (ATLAST) as a candidate large UV-Optical-Infrared (LUVOIR) surveyor

    NASA Astrophysics Data System (ADS)

    Bolcar, Matthew R.; Balasubramanian, Kunjithapatham; Clampin, Mark; Crooke, Julie; Feinberg, Lee; Postman, Marc; Quijada, Manuel; Rauscher, Bernard; Redding, David; Rioux, Norman; Shaklan, Stuart; Stahl, H. Philip; Stahle, Carl; Thronson, Harley

    2015-09-01

    The Advanced Technology Large Aperture Space Telescope (ATLAST) team has identified five key technologies to enable candidate architectures for the future large-aperture ultraviolet/optical/infrared (LUVOIR) space observatory envisioned by the NASA Astrophysics 30-year roadmap, Enduring Quests, Daring Visions. The science goals of ATLAST address a broad range of astrophysical questions from early galaxy and star formation to the processes that contributed to the formation of life on Earth, combining general astrophysics with direct-imaging and spectroscopy of habitable exoplanets. The key technologies are: internal coronagraphs, starshades (or external occulters), ultra-stable large-aperture telescopes, detectors, and mirror coatings. Selected technology performance goals include: 1x10-10 raw contrast at an inner working angle of 35 milli-arcseconds, wavefront error stability on the order of 10 pm RMS per wavefront control step, autonomous on-board sensing and control, and zero-read-noise single-photon detectors spanning the exoplanet science bandpass between 400 nm and 1.8 μm. Development of these technologies will provide significant advances over current and planned observatories in terms of sensitivity, angular resolution, stability, and high-contrast imaging. The science goals of ATLAST are presented and flowed down to top-level telescope and instrument performance requirements in the context of a reference architecture: a 10-meter-class, segmented aperture telescope operating at room temperature (~290 K) at the sun-Earth Lagrange-2 point. For each technology area, we define best estimates of required capabilities, current state-of-the-art performance, and current Technology Readiness Level (TRL) - thus identifying the current technology gap. We report on current, planned, or recommended efforts to develop each technology to TRL 5.

  11. Technology Development for the Advanced Technology Large Aperture Space Telescope (ATLAST) as a Candidate Large UV-Optical-Infrared (LUVOIR) Surveyor

    NASA Technical Reports Server (NTRS)

    Bolcar, Matthew R.; Balasubramanian, Kunjithapatha; Clampin, Mark; Crooke, Julie; Feinberg, Lee; Postman, Marc; Quijada, Manuel; Rauscher, Bernard; Redding, David; Rioux, Norman; hide

    2015-01-01

    The Advanced Technology Large Aperture Space Telescope (ATLAST) team has identified five key technologies to enable candidate architectures for the future large-aperture ultraviolet/optical/infrared (LUVOIR) space observatory envisioned by the NASA Astrophysics 30-year roadmap, Enduring Quests, Daring Visions. The science goals of ATLAST address a broad range of astrophysical questions from early galaxy and star formation to the processes that contributed to the formation of life on Earth, combining general astrophysics with direct-imaging and spectroscopy of habitable exoplanets. The key technologies are: internal coronagraphs, starshades (or external occulters), ultra-stable large-aperture telescopes, detectors, and mirror coatings. Selected technology performance goals include: 1x10?10 raw contrast at an inner working angle of 35 milli-arcseconds, wavefront error stability on the order of 10 pm RMS per wavefront control step, autonomous on-board sensing & control, and zero-read-noise single-photon detectors spanning the exoplanet science bandpass between 400 nm and 1.8 µm. Development of these technologies will provide significant advances over current and planned observatories in terms of sensitivity, angular resolution, stability, and high-contrast imaging. The science goals of ATLAST are presented and flowed down to top-level telescope and instrument performance requirements in the context of a reference architecture: a 10-meter-class, segmented aperture telescope operating at room temperature (290 K) at the sun-Earth Lagrange-2 point. For each technology area, we define best estimates of required capabilities, current state-of-the-art performance, and current Technology Readiness Level (TRL) - thus identifying the current technology gap. We report on current, planned, or recommended efforts to develop each technology to TRL 5.

  12. Weak scratch detection and defect classification methods for a large-aperture optical element

    NASA Astrophysics Data System (ADS)

    Tao, Xian; Xu, De; Zhang, Zheng-Tao; Zhang, Feng; Liu, Xi-Long; Zhang, Da-Peng

    2017-03-01

    Surface defects on optics cause optic failure and heavy loss to the optical system. Therefore, surface defects on optics must be carefully inspected. This paper proposes a coarse-to-fine detection strategy of weak scratches in complicated dark-field images. First, all possible scratches are detected based on bionic vision. Then, each possible scratch is precisely positioned and connected to a complete scratch by the LSD and a priori knowledge. Finally, multiple scratches with various types can be detected in dark-field images. To classify defects and pollutants, a classification method based on GIST features is proposed. This paper uses many real dark-field images as experimental images. The results show that this method can detect multiple types of weak scratches in complex images and that the defects can be correctly distinguished with interference. This method satisfies the real-time and accurate detection requirements of surface defects.

  13. Large-aperture quantum well shutters for fast retroreflected optical data links in free space

    NASA Astrophysics Data System (ADS)

    Gilbreath, G. Charmaine; Rabinovich, William S.; Mahon, Rita; Corson, Michael R.; Stell, Mena F.; Katzer, D. Scott; Ikossi-Anastasiou, Kiki; Meehan, Timothy J.; Kline, John F.

    1999-05-01

    This paper reports progress on the development of a fast modulating retroreflector for a free space optical data link. A previous publication reported sustaining video over a 17 meter link using a multiple quantum well shutter with a diameter of 0.5 cm at a rate on the order of 0.5 Mbps, limited by the demonstration electronics. This work describes improvements in the device performance, which is on the order of 4 Mbps to 6 Mbps with a Bit Error Rates of 10-6 over a robust optical link. This device lends itself to an array configuration for long range applications and will clearly support T1 rates of 1.54 Mbps, and higher.

  14. Cleaning mechanism of particle contaminants on large aperture optical components by using air knife sweeping technology

    NASA Astrophysics Data System (ADS)

    Niu, Longfei; Liu, Hao; Miao, Xinxiang; Lv, Haibing; Yuan, Xiaodong; Zhou, Hai; Yao, Caizhen; Zhou, Guorui; Li, Qin

    2017-05-01

    The cleaning mechanism of optical surface particle contaminants in the light pneumatic tube was simulated based on the static equations and JKR model. Cleaning verification experiment based on air knife sweeping system and on-line monitoring system in high power laser facility was set up in order to verify the simulated results. Results showed that the removal ratio is significantly influenced by sweeping velocity and angle. The removal ratio can reach to 94.3% by using higher input pressure of the air knife, demonstrating that the air knife sweeping technology is useful for maintaining the surface cleanliness of optical elements, and thus guaranteeing the long-term stable running of the high power laser facility.

  15. Large-Aperture Optical Modulator Materials. Lead Lanthanum Zirconate Titanate Ceramic and Lithium Niobate Crystal Show Promise as Modulator Materials for Optical Transmitters with up to 6-inch Apertures

    DTIC Science & Technology

    1977-10-11

    a magneto - optica , modulator with a 6-inch or larger aperture for use in a- analog mode would require further extensive development by the...individual modulator elements. CONTENTS INTRODUCTION... page 3 PRELIMINARY ASSESSMENT... 3 Magneto -optical Materials... 3 Electro-optical Materials... 5...modulator requirements specified above, active optical materials (electro-optical. magneto -optical. acousto-optical. etc) employing solid-state technology

  16. the Large Aperture GRB Observatory

    SciTech Connect

    Bertou, Xavier

    2009-04-30

    The Large Aperture GRB Observatory (LAGO) aims at the detection of high energy photons from Gamma Ray Bursts (GRB) using the single particle technique (SPT) in ground based water Cherenkov detectors (WCD). To reach a reasonable sensitivity, high altitude mountain sites have been selected in Mexico (Sierra Negra, 4550 m a.s.l.), Bolivia (Chacaltaya, 5300 m a.s.l.) and Venezuela (Merida, 4765 m a.s.l.). We report on the project progresses and the first operation at high altitude, search for bursts in 6 months of preliminary data, as well as search for signal at ground level when satellites report a burst.

  17. 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.

  18. Manufacture of Large-Aperture Diffractive Optics and Ultrathin Optics for High-Power Laser and Space Applications

    SciTech Connect

    Britten, J A

    2002-01-18

    We have developed equipment and technology for fabricating submicron pitch, high-efficiency diffraction gratings over meter-scale apertures that are used for pulse compression in ultrafast systems around the world. We have also developed wet-etch figuring (WEF) to generate arbitrary continuous contours on ultrathin glass substrates in a closed loop process. The current and future states of these technologies will be discussed.

  19. Sub-aperture stitching test of a cylindrical mirror with large aperture

    NASA Astrophysics Data System (ADS)

    Xue, Shuai; Chen, Shanyong; Shi, Feng; Lu, Jinfeng

    2016-09-01

    Cylindrical mirrors are key optics of high-end equipment of national defense and scientific research such as high energy laser weapons, synchrotron radiation system, etc. However, its surface error test technology develops slowly. As a result, its optical processing quality can not meet the requirements, and the developing of the associated equipment is hindered. Computer Generated-Hologram (CGH) is commonly utilized as null for testing cylindrical optics. However, since the fabrication process of CGH with large aperture is not sophisticated yet, the null test of cylindrical optics with large aperture is limited by the aperture of the CGH. Hence CGH null test combined with sub-aperture stitching method is proposed to break the limit of the aperture of CGH for testing cylindrical optics, and the design of CGH for testing cylindrical surfaces is analyzed. Besides, the misalignment aberration of cylindrical surfaces is different from that of the rotational symmetric surfaces since the special shape of cylindrical surfaces, and the existing stitching algorithm of rotational symmetric surfaces can not meet the requirements of stitching cylindrical surfaces. We therefore analyze the misalignment aberrations of cylindrical surfaces, and study the stitching algorithm for measuring cylindrical optics with large aperture. Finally we test a cylindrical mirror with large aperture to verify the validity of the proposed method.

  20. Partially filled aperture interferometric telescopes: achieving large aperture and coronagraphic performance

    NASA Astrophysics Data System (ADS)

    Moretto, Gil; Kuhn, Jeff R.; Berdyugina, Svetlana V.; Langlois, Maud; Tallon, Michel; Thiébaut, Eric; Halliday, David

    2016-08-01

    The exponential growth in exoplanet studies and science cases requiring high contrast observations is a powerful reason for developing very large optical systems optimized for narrow-field science. Concepts which cross the boundary between fixed aperture telescopes and interferometers, combined with technologies that decrease the system moving mass, can violate the cost and mass scaling laws that make conventional large-aperture telescopes relatively expensive. Here we describe concepts of large, filled-aperture (Colossus) and partially filled aperture (ParFAIT) interferometric optical/IR telescope systems which break this scaling relation. These systems are dedicated to high dynamic range science such as detecting life and even civilizations on Earth-like planets.

  1. Advanced optics experiments using nonuniform aperture functions

    NASA Astrophysics Data System (ADS)

    Wood, Lowell T.

    2013-05-01

    A method to create instructive, nonuniform aperture functions using spatial frequency filtering is described. The diffraction from a single slit in the Fresnel limit and the interference from a double slit in the Fraunhofer limit are spatially filtered to create electric field distributions across an aperture to produce apodization, inverse apodization or super-resolution, and apertures with phase shifts across their widths. The diffraction effects from these aperture functions are measured and calculated. The excellent agreement between the experimental results and the calculated results makes the experiment ideal for use in an advanced undergraduate or graduate optics laboratory to illustrate experimentally several effects in Fourier optics.

  2. Integrated Optical Synthetic Aperture Radar Processor.

    DTIC Science & Technology

    1987-09-01

    rugged, low - cost , lov-power optical synthetic aperture radar processor for real- time image formation aboard airborne and spaceborne platforms. The...of this research program was initiation of the development of a compact, rugged, low - cost , low -power optical synthetic aperture radar processor for... low power consumption, size/weight and cost make the optical implementation the only practical solution in many SAR imaging applications. This research

  3. Diffraction smoothing aperture for an optical beam

    DOEpatents

    Judd, O'Dean P.; Suydam, Bergen R.

    1976-01-01

    The disclosure is directed to an aperture for an optical beam having an irregular periphery or having perturbations imposed upon the periphery to decrease the diffraction effect caused by the beam passing through the aperture. Such apertures are particularly useful with high power solid state laser systems in that they minimize the problem of self-focusing which frequently destroys expensive components in such systems.

  4. Large-aperture CCD x-ray detector for protein crystallography using a fiber-optic taper

    NASA Astrophysics Data System (ADS)

    Strauss, Michael G.; Westbrook, Edwin M.; Naday, Istvan; Coleman, T. A.; Westbrook, Mary L.; Travis, D. J.; Sweet, Robert M.; Pflugrath, J. W.; Stanton, Martin J.

    1991-07-01

    A detector with a 114 mm aperture, based on a charge-coupled device (CCD), has been designed for x-ray diffraction studies in protein crystallography. The detector was tested on a beamline of the National Synchrotron Light Source at Brookhaven National Laboratory with a beam intensity greater than 10(superscript 9) x-ray photons/s. A fiber-optic taper, an image intensifier, and a lens demagnify, intensify, and focus the image onto a CCD having 512 X 512 pixels. A detective quantum efficiency (DQE) of 0.36 was obtained by evaluating the statistical uncertainty in the detector output. The dynamic range of a 4 X 4 pixel resolution element, comparable in size to a diffraction peak, was 10 (superscript 4). The point-spread function shows FWHM resolution of approximately 1 pixel, where a pixel on the detector face is 160 micrometers . A complete data set, consisting of forty-five 1 degree(s) rotation frames, was obtained in just 36 s of x-ray exposure to a crystal of chicken egg-white lysozyme. In a separate experiment, a lysozyme data set consisting of 495 0.1 degree(s) frames, was processed by the MADNES data reduction program, yielding symmetry R-factors for the data of 3.2- 3.5%. Diffraction images from crystals of the myosin S1 head (a equals 275 angstroms) were also recorded. The Bragg spots, only 5 pixels apart, were resolved but were not sufficiently separated to process these data. Changes in the detector design which will improve the DQE and spatial resolution are outlined. The overall performance showed that this type of detector is well suited for x-ray scattering investigations with synchrotron sources.

  5. Optical Transmission Properties of Dielectric Aperture Arrays

    NASA Astrophysics Data System (ADS)

    Yang, Tao

    Optical detection devices such as optical biosensors and optical spectrometers are widely used in many applications for the functions of measurements, inspections and analysis. Due to the large dimension of prisms and gratings, the traditional optical devices normally occupy a large space with complicated components. Since cheaper and smaller optical devices are always in demand, miniaturization has been kept going for years. Thanks to recent fabrication advances, nanophotonic devices such as semiconductor laser chips have been growing in number and diversity. However, the optical biosensor chips and the optical spectrometer chips are seldom reported in the literature. For the reason of improving system integration, the study of ultra-compact, low-cost, high-performance and easy-alignment optical biosensors and optical spectrometers are imperative. This thesis is an endeavor in these two subjects and will present our research work on studying the optical transmission properties of dielectric aperture arrays and developing new optical biosensors and optical spectrometers. The first half of the thesis demonstrates that the optical phase shift associated with the surface plasmon (SP) assisted extraordinary optical transmission (EOT) in nano-hole arrays fabricated in a metal film has a strong dependence on the material refractive index value in close proximity to the holes. A novel refractive index sensor based on detecting the EOT phase shift is proposed by building a model. This device readily provides a 2-D biosensor array platform for non-labeled real-time detection of a variety of organic and biological molecules in a sensor chip format, which leads to a high packing density, minimal analyte volumes, and a large number of parallel channels while facilitating high resolution imaging and supporting a large space-bandwidth product (SBP). Simulation (FDTD Solutions, Lumerical Solutions Inc) results indicate an achievable sensitivity limit of 4.37x10-9 refractive index

  6. Eyeglass: A Very Large Aperture Diffractive Space Telescope

    SciTech Connect

    Hyde, R; Dixit, S; Weisberg, A; Rushford, M

    2002-07-29

    Eyeglass is a very large aperture (25-100 meter) space telescope consisting of two distinct spacecraft, separated in space by several kilometers. A diffractive lens provides the telescope's large aperture, and a separate, much smaller, space telescope serves as its mobile eyepiece. Use of a transmissive diffractive lens solves two basic problems associated with very large aperture space telescopes; it is inherently fieldable (lightweight and flat, hence packagable and deployable) and virtually eliminates the traditional, very tight, surface shape tolerances faced by reflecting apertures. The potential drawback to use of a diffractive primary (very narrow spectral bandwidth) is eliminated by corrective optics in the telescope's eyepiece. The Eyeglass can provide diffraction-limited imaging with either single-band, multiband, or continuous spectral coverage. Broadband diffractive telescopes have been built at LLNL and have demonstrated diffraction-limited performance over a 40% spectral bandwidth (0.48-0.72 {micro}m). As one approach to package a large aperture for launch, a foldable lens has been built and demonstrated. A 75 cm aperture diffractive lens was constructed from 6 panels of 1 m thick silica; it achieved diffraction-limited performance both before and after folding. This multiple panel, folding lens, approach is currently being scaled-up at LLNL. We are building a 5 meter aperture foldable lens, involving 72 panels of 700 {micro}m thick glass sheets, diffractively patterned to operate as coherent f/50 lens.

  7. Ultrasound Beamforming Methods for Large Coherent Apertures

    NASA Astrophysics Data System (ADS)

    Bottenus, Nick

    This dissertation investigates the use of large coherent ultrasound apertures to improve diagnostic image quality for deep clinical targets. The current generation of ultrasound scanners restrict aperture size and geometry based on hardware limitations and field of view requirements at the expense of image quality. This work posits that, without these restrictions, ultrasound could be used for higher quality non-invasive imaging. To support this claim, an experimental device was constructed to acquire in vivo liver images with a synthetic aperture spanning at least 35 degrees at a radius of 10.2 cm with a scan time under one second. Using a 2.5 MHz commercial matrix array with the device, a lateral resolution of 0.45 mm at a depth of 11.6 cm was achieved, surpassing the capabilities of existing commercial systems. This work formed the basis for an in-depth investigation of the clinical promise of large aperture imaging. Ex vivo study of volumetric imaging through the human abdominal wall demonstrated the ability of large apertures to improve target detectability at depth by significantly increasing lateral resolution, even in the presence of tissue-induced aberration and reverberation. For various abdominal wall samples studied, full-width at half-maximum resolution was increased by 1.6 to 4.3 times using a 6.4 cm swept synthetic aperture compared to conventional imaging. Harmonic plane wave imaging was shown to limit the impact of reverberation clutter from the tissue layer and produce images with the highest target detectability, up to a 45.9% improvement in contrast-to-noise ratio (CNR) over fundamental imaging. This study was corroborated by simulation of a 10 cm concave matrix array imaging through an abdominal wall based on the Visible Human Project data set. The large aperture data were processed in several ways, including in their entirety as a fully populated large array as well as mimicking the swept synthetic aperture configuration. Image quality

  8. Enhanced Optical Transmission with Coaxial Apertures

    NASA Astrophysics Data System (ADS)

    Haftel, Michael; Schlockermann, Carl; Orbons, Shannon; Roberts, Ann; Jamieson, David; Freeman, Darren; Luther-Davies, Barry

    2007-03-01

    Recently it has been shown that ``cylindrical'' surface plasmons (CSP's) on cylindrical interfaces of coaxial ring apertures produce a new form of extraordinary optical transmission (EOT) that extends to ever increasing wavelengths as the dielectric ring narrows. Using analytic and FDTD calculations we present some of the consequences of CSP's on EOT as well as experimental confirmation of such effects. We find that EOT, even with cylindrical apertures, is aided by the increase in cutoff wavelength due to CSP's, which is a consequence of the mode structure of individual apertures. CSP effects also explain most of the long-wavelength features of transmission spectra measured for CR apertures. We also show that CSP's can be ``spoofed'' at low frequencies by coaxial apertures in metamaterials consisting of a (macroscopic) periodic dielectric structure embedded in a perfect conductor. F. I. Baida et al., Phys. Rev. B 67, 155314 (2003); M.I Haftel et al., Appl. Phys. Lett. 88, 193104 (2006).

  9. OpTIIX: An ISS-Based Testbed Paving the Roadmap Toward a Next Generation Large Aperture UV/Optical Space Telescope

    NASA Technical Reports Server (NTRS)

    Carpenter, Kenneth G.; Etemad, Shar; Seery, Bernard D.; Thronson, Harley; Burdick, Gary M.; Coulter, Dan; Goullioud, Renaud; Green, Joseph J.; Liu, Fengchuan; Ess, Kim; Postman, Marc; Sparks, Williams

    2012-01-01

    The next generation large aperture UV/Optical space telescope will need a diameter substantially larger than even that of JWST in order to address some of the most compelling unanswered scientific quests. These quests include understanding the earliest phases of the Universe and detecting life on exo-planets by studying spectra of their atmospheres. Such 8-16 meter telescopes face severe challenges in terms of cost and complexity and are unlikely to be affordable unless a new paradigm is adopted for their design and construction. The conventional approach is to use monolithic or preassembled segmented mirrors requiring complicated and risky deployments and relying on future heavy-lift vehicles, large fairings and complex geometry. The new paradigm is to launch component modules on relatively small vehicles and then perform in-orbit robotic assembly of those modules. The Optical Testbed and Integration on ISS eXperiment (OpTIIX) is designed to demonstrate, at low cost by leveraging the infrastructure provided by ISS, telescope assembly technologies and end-to-end optical system technologies. The use of ISS as a testbed permits the concentration of resources on reducing the technical risks associated with robotically integrating the components. These include laser metrology and wavefront sensing and control (WFS&C) systems, an imaging instrument, lightweight, low-cost deformable primary mirror segments and the secondary mirror. These elements are then aligned to a diffraction-limited optical system in space. The capability to assemble the optical system and remove and replace components via the existing ISS robotic systems like the Special Purpose Dexterous Manipulator (SPDM), or by the ISS flight crew, allows for future experimentation, as well as repair.

  10. Large Aperture Electrostatic Dust Detector

    SciTech Connect

    C.H. Skinner, R. Hensley, and A.L Roquemore

    2007-10-09

    Diagnosis and management of dust inventories generated in next-step magnetic fusion devices is necessary for their safe operation. A novel electrostatic dust detector, based on a fine grid of interlocking circuit traces biased to 30 or 50 ν has been developed for the detection of dust particles on remote surfaces in air and vacuum environments. Impinging dust particles create a temporary short circuit and the resulting current pulse is recorded by counting electronics. Up to 90% of the particles are ejected from the grid or vaporized suggesting the device may be useful for controlling dust inventories. We report measurements of the sensitivity of a large area (5x5 cm) detector to microgram quantities of dust particles and review its applications to contemporary tokamaks and ITER.

  11. A high-performance passband-agile hyperspectral imager using a large aperture acousto-optic tuneable filter

    NASA Astrophysics Data System (ADS)

    Pannell, Christopher N.; Ward, Jon D.; Wachman, Elliot S.; Zhang, Bill G.; Reed, Murray K.

    2015-03-01

    We describe an acousto-optic tunable filter (AOTF) based hyper-spectral imaging microscope system that allows real time unmixing of the combination of cellular morphology staining and multiple biomarker staining on a single microscope slide. We describe several advances in AOTF technology such as novel acoustic apodization schemes in the longitudinal and transverse directions that have greatly improved image quality. In addition we demonstrate construction leading to improved broadband matching which in turn allows in lower power operation allowing up to 16 simultaneous arbitrary-wavelength optical channels to be processed if necessary. We discuss optical schemes and other factors that allow low stray light and rejection of out-of-band light. A hyper-spectral imaging bright field microscope using these advances demonstrates pathology results that have great potential for clinical use.

  12. Design of large aperture focal plane shutter

    NASA Astrophysics Data System (ADS)

    Hu, Jia-wen; Ma, Wen-li; Huang, Jin-long

    2012-09-01

    To satisfy the requirement of large telescope, a large aperture focal plane shutter with aperture size of φ200mm was researched and designed to realize, which could be started and stopped in a relative short time with precise position, and also the blades could open and close at the same time at any orientation. Timing-belts and stepper motors were adopted as the drive mechanism. Velocity and position of the stepper motors were controlled by the PWM pulse generated by DSP. Exponential curve is applied to control the velocity of the stepper motors to make the shutter start and stop in a short time. The closing/open time of shutter is 0.2s, which meets the performance requirements of large telescope properly.

  13. Self-Referencing Hartmann Test for Large-Aperture Telescopes

    NASA Technical Reports Server (NTRS)

    Korechoff, Robert P.; Oseas, Jeffrey M.

    2010-01-01

    A method is proposed for end-to-end, full aperture testing of large-aperture telescopes using an innovative variation of a Hartmann mask. This technique is practical for telescopes with primary mirrors tens of meters in diameter and of any design. Furthermore, it is applicable to the entire optical band (near IR, visible, ultraviolet), relatively insensitive to environmental perturbations, and is suitable for ambient laboratory as well as thermal-vacuum environments. The only restriction is that the telescope optical axis must be parallel to the local gravity vector during testing. The standard Hartmann test utilizes an array of pencil beams that are cut out of a well-corrected wavefront using a mask. The pencil beam array is expanded to fill the full aperture of the telescope. The detector plane of the telescope is translated back and forth along the optical axis in the vicinity of the nominal focal plane, and the centroid of each pencil beam image is recorded. Standard analytical techniques are then used to reconstruct the telescope wavefront from the centroid data. The expansion of the array of pencil beams is usually accomplished by double passing the beams through the telescope under test. However, this requires a well-corrected, autocollimation flat, the diameter or which is approximately equal to that of the telescope aperture. Thus, the standard Hartmann method does not scale well because of the difficulty and expense of building and mounting a well-corrected, large aperture flat. The innovation in the testing method proposed here is to replace the large aperture, well-corrected, monolithic autocollimation flat with an array of small-aperture mirrors. In addition to eliminating the need for a large optic, the surface figure requirement for the small mirrors is relaxed compared to that required of the large autocollimation flat. The key point that allows this method to work is that the small mirrors need to operate as a monolithic flat only with regard to

  14. Coherent optical system of modular imaging collectors (COSMIC) - An approach for a large aperture high angular resolution telescope in space

    NASA Technical Reports Server (NTRS)

    Davis, B.; Hunt, G.; Nein, M.; Korsch, D.

    1984-01-01

    Very high angular resolution can be achieved in UV/optical astronomy through interferometers in space. A concept analysis of COSMIC, which may be placed into orbit by the Space Shuttle in the late 1990's, is discussed. The photon-collecting area is three times larger than that of Space Telescope (ST), and exceeds its resolution by approximately an order of magnitude. Several alternative configurations are presented to scope the extent of design approaches which may be achievable within the transportation capability of the Space Shuttle.

  15. Single-pulse driven, large-aperture 2×1 array plasma-electrodes optical switch for SG-II upgrading facility

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Wu, Dengsheng; Zheng, Jiangang; Zheng, Kuixing; Zhu, Qihua; Zhang, Xiongjun

    2014-12-01

    We demonstrate the design and performance of an optical switch that has been constructed for the SG-II upgrading facility. The device is a longitudinal, potassium di-hydrogen phosphate (KDP), 360 mm×360 mm aperture, and 2×1 array electro-optical switch driven by a 20 kV output switching-voltage pulse generator through two plasma electrodes produced at the rise edge of the switching-voltage pulse. The results show that the temporal responses and the spatial performance of the optical switch fulfill the operation requirements of the SG-II upgrading facility.

  16. Optical aperture synthesis with electronically connected telescopes.

    PubMed

    Dravins, Dainis; Lagadec, Tiphaine; Nuñez, Paul D

    2015-04-16

    Highest resolution imaging in astronomy is achieved by interferometry, connecting telescopes over increasingly longer distances and at successively shorter wavelengths. Here, we present the first diffraction-limited images in visual light, produced by an array of independent optical telescopes, connected electronically only, with no optical links between them. With an array of small telescopes, second-order optical coherence of the sources is measured through intensity interferometry over 180 baselines between pairs of telescopes, and two-dimensional images reconstructed. The technique aims at diffraction-limited optical aperture synthesis over kilometre-long baselines to reach resolutions showing details on stellar surfaces and perhaps even the silhouettes of transiting exoplanets. Intensity interferometry circumvents problems of atmospheric turbulence that constrain ordinary interferometry. Since the electronic signal can be copied, many baselines can be built up between dispersed telescopes, and over long distances. Using arrays of air Cherenkov telescopes, this should enable the optical equivalent of interferometric arrays currently operating at radio wavelengths.

  17. Large-aperture broadband sapphire windows for common aperture, target acquisition, tracking, and surveillance systems

    NASA Astrophysics Data System (ADS)

    Askinazi, Joel

    1997-06-01

    State of the art optical sensing systems performing target acquisition/tracking and surveillance functions are being designed to incorporate a number of sensors into one package. These include visual and MWIR cameras, FLIRs, and laser range finders. These combined systems are being configured to view through a common aperture window. Typical window diameters are to eleven inches, but some surveillance applications have windows approaching twenty inches in diameter. These sensor windows typically operate in hostile environments including very high pressure differentials, large thermal gradients, and severe rain and sand abrasion. EMI/EMC protection and de-icing capabilities are also commonly required. For airborne applications and to minimize thermal gradients, thinner, lightweight, high strength windows are also necessary. Sapphire is an ideal window material to satisfy these requirements due to its high strength, UV-MWIR bandpass, minimal optical scatter, excellent index of refraction homogeneity and very high scratch/impact resistance. Associated optical fabrication, grid lithography and optical coating processes have been developed at Hughes Danbury for sapphire windows. This paper addresses the development of a family of large aperture, broadband sapphire windows which also provide EMI/EMC protection and de-icing capabilities. The resulting design configuration and performance characteristics are also addressed. Future technology development requirements are also discussed.

  18. Large-aperture interferometer using local reference beam

    NASA Technical Reports Server (NTRS)

    Howes, W. L.

    1982-01-01

    A large-aperture interferometer was devised by adding a local-reference-beam-generating optical system to a schlieren system. Two versions of the interferometer are demonstrated, one employing 12.7 cm (5 in.) diameter schlieren optics, the other employing 30.48 cm (12 in.) diameter parabolic mirrors in an off-axis system. In the latter configuration a cylindrical lens is introduced near the light source to correct for astigmatism. A zone plate is a satisfactory decollimating element in the reference-beam arm of the interferometer. Attempts to increase the flux and uniformity of irradiance in the reference beam by using a diffuser are discussed.

  19. Bridgman growth of large-aperture yttrium calcium oxyborate crystal

    SciTech Connect

    Wu, Anhua; Jiang, Linwen; Qian, Guoxing; Zheng, Yanqing; Xu, Jun; Shi, Erwei

    2012-09-15

    Highlights: ► YCOB is a novel non-linear optical crystal possessing good thermal, mechanical and nonlinear optical properties. ► Large size crystal growth is key technology question for YCOB crystal. ► YCOB crystals 3 in. in diameter were grown with modified vertical Bridgman method. ► It is a more effective growth method to obtain large size and high quality YCOB crystal. -- Abstract: Large-aperture yttrium calcium oxyborate YCa{sub 4}O(BO{sub 3}){sub 3} (YCOB) crystals with 3 in. in diameter were grown with modified vertical Bridgman method, and the large crystal plate (63 mm × 68 mm × 20 mm) was harvested for high-average power frequency conversion system. The crack, facet growth and spiral growth can be effectively controlled in the as-grown crystal, and Bridgman method displays more effective in obtain large size and high quality YCOB crystal plate than Czochralski technique.

  20. Saturation of the Large Aperture Scintillometer

    NASA Astrophysics Data System (ADS)

    Kohsiek, W.; Meijninger, W. M. L.; Debruin, H. A. R.; Beyrich, F.

    2006-10-01

    The saturation aspects of a large aperture (0.3 m) scintillometer operating over a 10-km path were investigated. Measurements were made over mainly forested, hilly terrain with typical maximum sensible heat fluxes of 300-400 W m -2, and over flat terrain with mainly grass, and typical maximum heat fluxes of 100-150 W m-2. Scintillometer-based fluxes were compared with eddy-correlation observations. Two different schemes for calculating the reduction of scintillation caused by saturation were applied: one based on the work of Hill and Clifford, the other based on Frehlich and Ochs. Without saturation correction, the scintillation fluxes were lower than the eddy-correlation fluxes; the saturation correction according to Frehlich and Ochs increased the scintillometer fluxes to an unrealistic level. Correcting the fluxes after the theory of the Hill and Clifford gave satisfying results

  1. KAOS: kilo-aperture optical spectrograph

    NASA Astrophysics Data System (ADS)

    Barden, Samuel C.; Dey, Arjun; Boyle, Brian; Glazebrook, Karl

    2004-09-01

    A design is described for a potential new facility capable of taking detailed spectroscopy of millions of objects in the Universe to explore the complexity of the Universe and to answer fundamental questions relating to the equation of state of dark energy and to how the Milky Way galaxy formed. The specific design described is envisioned for implementation on the Gemini 8-meter telescopes. It utilizes a 1.5° field of view and samples that field with up to ~5000 apertures. This Kilo-Aperture Optical Spectrograph (KAOS) is mounted at prime focus with a 4-element corrector, atmospheric dispersion compensator (ADC), and an Echidna-style fiber optic positioner. The ADC doubles as a wobble plate, allowing fast guiding that cancels out the wind buffeting of the telescope. The fibers, which can be reconfigured in less than 10 minutes, feed to an array of 12 spectrographs located in the pier of the telescope. The spectrographs are capable of provided spectral resolving powers of a few thousand up to about 40,000.

  2. Lyot coronagraph design study for large, segmented space telescope apertures

    NASA Astrophysics Data System (ADS)

    Zimmerman, Neil T.; N'Diaye, Mamadou; St. Laurent, Kathryn E.; Soummer, Rémi; Pueyo, Laurent; Stark, Christopher C.; Sivaramakrishnan, Anand; Perrin, Marshall; Vanderbei, Robert J.; Kasdin, N. J.; Shaklan, Stuart; Carlotti, Alexis

    2016-07-01

    Recent efforts combining the optimization techniques of apodized pupil Lyot coronagraphs (APLC) and shaped pupils have demonstrated the viability of a binary-transmission mask architecture for extremely high contrast (10-10) exoplanet imaging. We are now building on those innovations to carry out a survey of Lyot coronagraph performance for large, segmented telescope apertures. These apertures are of the same kind under considera- tion for NASA's Large UV/Optical/IR (LUVOIR) observatory concept. To map the multi-dimensional design parameter space, we have developed a software toolkit to manage large sets of mask optimization programs and execute them on a computing cluster. Here we summarize a preliminary survey of 500 APLC solutions for 4 reference hexagonal telescope apertures. Several promising designs produce annular, 10-10 contrast dark zones down to inner working angle 4λ0=D over a 15% bandpass, while delivering a half-max PSF core throughput of 18%. We also report our progress on devising solutions to the challenges of Lyot stop alignment/fabrication tolerance that arise in this contrast regime.

  3. The modular design of large-aperture zoom system

    NASA Astrophysics Data System (ADS)

    Liu, Kai; Jiang, Kai; Yan, Peipei; Shan, Qiu-sha; Duan, Jing; Li, Gang

    2016-10-01

    According to the large aperture, long focal length zoom system design, the structure of the optical system based on the modular concept is proposed. The structure is constituted of an afocal compression telescope and a zoom system. The parts of each other are individually designed. The aberrations of them are independently. Because of this, the alignment of the system and the difficulty of test are greatly reduced. It is easily replaced by changing the zoom system parts, which can achieve other different focal length and ratio. Using afocal compression telescope greatly reduces the radial aperture of the zoom group, simplifies the system structure and reduces the cost. Meanwhile, the variable stop is placed in the vicinity of the primary mirror. It is instead of the zoom system used in floating variable stop. In addition, the problem about large aperture zoom system pupil matching is solved perfectly. In this article, four methods of pupil matching are given and the advantages and disadvantages of them are analyzed. Using this optical structure, a zoom system is designed, which is working in the visible wavelength band with variable focal length between 900mm and 4500mm, 500mm maximum aperture. The axial dimension of the system is less than 650mm. The maximum diameter of zoom system parts is less than 40 mm. Moreover, the distances of the zoom group and compensating group are all less than 60 mm. Besides, the motion curves of each other are given in the article. The Modulation Transfer Function (MTF) values of the system are greater than 0.3 at 48lp/mm across different focal length and field pointing on the axis. The design results show that the imaging quality is excellent, the structure is compact, and the alignment and test are easy. The imaging requirements of zoom system are all satisfied.

  4. Optical aperture synthesis with electronically connected telescopes

    PubMed Central

    Dravins, Dainis; Lagadec, Tiphaine; Nuñez, Paul D.

    2015-01-01

    Highest resolution imaging in astronomy is achieved by interferometry, connecting telescopes over increasingly longer distances and at successively shorter wavelengths. Here, we present the first diffraction-limited images in visual light, produced by an array of independent optical telescopes, connected electronically only, with no optical links between them. With an array of small telescopes, second-order optical coherence of the sources is measured through intensity interferometry over 180 baselines between pairs of telescopes, and two-dimensional images reconstructed. The technique aims at diffraction-limited optical aperture synthesis over kilometre-long baselines to reach resolutions showing details on stellar surfaces and perhaps even the silhouettes of transiting exoplanets. Intensity interferometry circumvents problems of atmospheric turbulence that constrain ordinary interferometry. Since the electronic signal can be copied, many baselines can be built up between dispersed telescopes, and over long distances. Using arrays of air Cherenkov telescopes, this should enable the optical equivalent of interferometric arrays currently operating at radio wavelengths. PMID:25880705

  5. Fresnel Lenses for Wide-Aperture Optical Receivers

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid

    2004-01-01

    Wide-aperture receivers for freespace optical communication systems would utilize Fresnel lenses instead of conventional telescope lenses, according to a proposal. Fresnel lenses weigh and cost much less than conventional lenses having equal aperture widths. Plastic Fresnel lenses are commercially available in diameters up to 5 m large enough to satisfy requirements for aperture widths of the order of meters for collecting sufficient light in typical long-distance free-space optical communication systems. Fresnel lenses are not yet suitable for high-quality diffraction-limited imaging, especially in polychromatic light. However, optical communication systems utilize monochromatic light, and there is no requirement for high-quality imaging; instead, the basic requirement for an optical receiver is to collect the incoming monochromatic light over a wide aperture and concentrate the light onto a photodetector. Because of lens aberrations and diffraction, the light passing through any lens is focused to a blur circle rather than to a point. Calculations for some representative cases of wide-aperture non-diffraction-limited Fresnel lenses have shown that it should be possible to attain blur-circle diameters of less than 2 mm. Preferably, the blur-circle diameter should match the width of the photodetector. For most high-bandwidth communication applications, the required photodetector diameters would be about 1 mm. In a less-preferable case in which the blur circle was wider than a single photodetector, it would be possible to occupy the blur circle with an array of photodetectors. As an alternative to using a single large Fresnel lens, one could use an array of somewhat smaller lenses to synthesize the equivalent aperture area. Such a configuration might be preferable in a case in which a single Fresnel lens of the requisite large size would be impractical to manufacture, and the blur circle could not be made small enough. For example one could construct a square array

  6. Extraordinary optical transmission through patterned subwavelength apertures.

    SciTech Connect

    Kemme, Shanalyn A.; El-Kady, Ihab Fathy; Hadley, G. Ronald; Peters, David William; Lanes, Chris E.

    2004-12-01

    Light propagating through a subwavelength aperture can be dramatically increased by etching a grating in the metal around the hole. Moreover, light that would typically broadly diverge when passing through an unpatterned subwavelength hole can be directed into a narrow beam by utilizing a specific pattern around the aperture. While the increased transmission and narrowed angular emission appear to defy far-field diffraction theory, they are consistent with a fortuitous plasmon/photon coupling. In addition, the coupling between photons and surface plasmons affects the emissivity of a surface comprised of such structures. These properties are useful across several strategic areas of interest to Sandia. A controllable emission spectrum could benefit satellite and military application areas. Photolithography and near-field microscopy are natural applications for a system that controls light beyond the diffraction limit in a manner that is easily parallelizable. Over the one year of this LDRD, we have built or modified the numerical tools necessary to model such structures. These numerical codes and the knowledge base for using them appropriately will be available in the future for modeling work on surface plasmons or other optical modeling at Sandia. Using these tools, we have designed and optimized structures for various transmission or emission properties. We demonstrate the ability to design a metallic skin with an emissivity peak at a pre-determined wavelength in the spectrum. We optimize structures for maximum light transmission and show transmitted beams that beat the far-field diffraction limit.

  7. U-turn alternative to the large aperture switch

    SciTech Connect

    Vann, C.S.

    1994-03-09

    The primary alternative laser architecture is the U-turn design. The U-turn has significantly different cost and performance risks than the full-aperture switch, which makes it a highly desirable alternative. The U-turn was conceived at LLNL in 1992. A similar concept, the L-turn had already been discovered by the French at CEL-V. Both concepts are based on the multipass glass amplifier design, but the full-aperture Pockels cell and polarizer are replaced with smaller and less expensive optics. Eliminating the large switch and polarizer not only reduces component costs, it also provides options for shortening the laser which, in turn, could reduce the size and cost of the laser building. Efficient use of the amplifier aperture (small vignetting allowance) requires that the U-turn have a long transport spatial filter; however, this is not a disadvantage if a long spatial filter is already required for image relaying to the frequency converter. Given a long spatial filter, the U-turn is potentially more efficient because losses in the switch and polarizer are avoided.

  8. Geometrical Aberration Suppression for Large Aperture Sub-THz Lenses

    NASA Astrophysics Data System (ADS)

    Rachon, M.; Liebert, K.; Siemion, A.; Bomba, J.; Sobczyk, A.; Knap, W.; Coquillat, D.; Suszek, J.; Sypek, M.

    2017-03-01

    Advanced THz setups require high performance optical elements with large numerical apertures and small focal lengths. This is due to the high absorption of humid air and relatively low efficiency of commercially available detectors. Here, we propose a new type of double-sided sub-THz diffractive optical element with suppressed geometrical aberration for narrowband applications (0.3 THz). One side of the element is designed as thin structure in non-paraxial approach which is the exact method, but only for ideally flat elements. The second side will compensate phase distribution differences between ideal thin structure and real volume one. The computer-aided optimization algorithm is performed to design an additional phase distribution of correcting layer assuming volume designing of the first side of the element. The experimental evaluation of the proposed diffractive component created by 3D printing technique shows almost two times larger performance in comparison with uncorrected basic diffractive lens.

  9. Geometrical Aberration Suppression for Large Aperture Sub-THz Lenses

    NASA Astrophysics Data System (ADS)

    Rachon, M.; Liebert, K.; Siemion, A.; Bomba, J.; Sobczyk, A.; Knap, W.; Coquillat, D.; Suszek, J.; Sypek, M.

    2016-11-01

    Advanced THz setups require high performance optical elements with large numerical apertures and small focal lengths. This is due to the high absorption of humid air and relatively low efficiency of commercially available detectors. Here, we propose a new type of double-sided sub-THz diffractive optical element with suppressed geometrical aberration for narrowband applications (0.3 THz). One side of the element is designed as thin structure in non-paraxial approach which is the exact method, but only for ideally flat elements. The second side will compensate phase distribution differences between ideal thin structure and real volume one. The computer-aided optimization algorithm is performed to design an additional phase distribution of correcting layer assuming volume designing of the first side of the element. The experimental evaluation of the proposed diffractive component created by 3D printing technique shows almost two times larger performance in comparison with uncorrected basic diffractive lens.

  10. Large-aperture interferometer with local reference beam

    NASA Technical Reports Server (NTRS)

    Howes, W. L.

    1984-01-01

    A large-aperture interferometer was devised by adding a local-reference-beam-generating optical system to a schlieren system. Two versions of the interferometer are demonstrated, one employing 12.7 cm (5 in.) diameter schlieren optics, the other employing 30.48 cm (12 in.) diameter parabolic mirrors in an off-axis system. In the latter configuration a cylindrical lens is introduced near the light source to correct for astigmatism. A zone plate is a satisfactory decollimating element in the reference-beam arm of the interferometer. Attempts to increase the flux and uniformity of irradiance in the reference beam by using a diffuser are discussed. Previously announced in STAR as N83-13979

  11. Cavity-excited Huygens' metasurface antennas for near-unity aperture illumination efficiency from arbitrarily large apertures

    PubMed Central

    Epstein, Ariel; Wong, Joseph P. S.; Eleftheriades, George V.

    2016-01-01

    One of the long-standing problems in antenna engineering is the realization of highly directive beams using low-profile devices. In this paper, we provide a solution to this problem by means of Huygens' metasurfaces (HMSs), based on the equivalence principle. This principle states that a given excitation can be transformed to a desirable aperture field by inducing suitable electric and (equivalent) magnetic surface currents. Building on this concept, we propose and demonstrate cavity-excited HMS antennas, where the single-source-fed cavity is designed to optimize aperture illumination, while the HMS facilitates the current distribution that ensures phase purity of aperture fields. The HMS breaks the coupling between the excitation and radiation spectra typical to standard partially reflecting surfaces, allowing tailoring of the aperture properties to produce a desirable radiation pattern, without incurring edge-taper losses. The proposed low-profile design yields near-unity aperture illumination efficiencies from arbitrarily large apertures, offering new capabilities for microwave, terahertz and optical radiators. PMID:26790605

  12. Cavity-excited Huygens' metasurface antennas for near-unity aperture illumination efficiency from arbitrarily large apertures.

    PubMed

    Epstein, Ariel; Wong, Joseph P S; Eleftheriades, George V

    2016-01-21

    One of the long-standing problems in antenna engineering is the realization of highly directive beams using low-profile devices. In this paper, we provide a solution to this problem by means of Huygens' metasurfaces (HMSs), based on the equivalence principle. This principle states that a given excitation can be transformed to a desirable aperture field by inducing suitable electric and (equivalent) magnetic surface currents. Building on this concept, we propose and demonstrate cavity-excited HMS antennas, where the single-source-fed cavity is designed to optimize aperture illumination, while the HMS facilitates the current distribution that ensures phase purity of aperture fields. The HMS breaks the coupling between the excitation and radiation spectra typical to standard partially reflecting surfaces, allowing tailoring of the aperture properties to produce a desirable radiation pattern, without incurring edge-taper losses. The proposed low-profile design yields near-unity aperture illumination efficiencies from arbitrarily large apertures, offering new capabilities for microwave, terahertz and optical radiators.

  13. A modular approach toward extremely large apertures

    NASA Astrophysics Data System (ADS)

    Woods, A. A., Jr.

    1981-02-01

    Modular antenna construction can provide a significant increase in reflector aperture size over deployable reflectors. The modular approach allows reflective mesh surfaces to be supported by a minimum of structure. The kinematics of the selected deployable design approach were validated by the subscale demonstration model. Further design refinements on the module structural/joints and design optimization on intermodule joints are needed.

  14. Multi-aperture digital coherent combining for free-space optical communication receivers.

    PubMed

    Geisler, David J; Yarnall, Timothy M; Stevens, Mark L; Schieler, Curt M; Robinson, Bryan S; Hamilton, Scott A

    2016-06-13

    Space-to-ground optical communication systems can benefit from reducing the size, weight, and power profiles of space terminals. One way of reducing the required power-aperture product on a space platform is to implement effective, but costly, single-aperture ground terminals with large collection areas. In contrast, we present a ground terminal receiver architecture in which many small less-expensive apertures are efficiently combined to create a large effective aperture while maintaining excellent receiver sensitivity. This is accomplished via coherent detection behind each aperture followed by digitization. The digitized signals are then combined in a digital signal processing chain. Experimental results demonstrate lossless coherent combining of four lasercom signals, at power levels below 0.1 photons/bit/aperture.

  15. Joint of back-support in large aperture transport mirrors

    NASA Astrophysics Data System (ADS)

    Chen, X. J.; Wu, W. K.; Liu, C. C.; Wang, B. X.; Zhu, M. Z.; Que, X. H.

    2016-10-01

    The wavefront distortion can directly influence on the optics quality of laser beam in ICF laser facility. The gravity is one of the major factors that cause the wavefront distortion. The back-support technology of the large aperture transport mirror has been developed to lessen the wavefront distortion caused by gravity. In the back-support technology, a joint structure between the mirror and the metal back-support has been developed. The requirement of joint is that the firm connection is realized with less wavefront distortion introduced. The adhesive structure and expanding mandrel structure have been analyzed and tested. The back-support of transport mirror in target area use the expanding mandrel for the reasons of the technics and fundamental frequency. The choice of material, the calculation force of clamp, the test of tensile, and the wavefront distortion analysis of transport mirror have been developed. The results show that the expanding mandrel can be used for the back-support of the large aperture transport mirror.

  16. Large aperture compound lenses made of lithium

    NASA Astrophysics Data System (ADS)

    Cremer, J. T.; Piestrup, M. A.; Beguiristain, H. R.; Gary, C. K.; Pantell, R. H.

    2003-04-01

    We have measured the intensity profile and transmission of x rays focused by a series of biconcave parabolic unit lenses fabricated in lithium. For specified focal length and photon energy lithium compound refractive lenses (CRL) have a larger transmission, aperture size, and gain compared to aluminum, kapton, and beryllium CRLs. The lithium compound refractive lens was composed of 335 biconcave, parabolic unit lenses each with an on-axis radius of curvature of 0.95 mm. Two-dimensional focusing was obtained at 8.0 keV with a focal length of 95 cm. The effective aperture of the CRL was measured to be 1030 μm with on-axis (peak) transmissions of 27% and an on-axis intensity gain of 18.9.

  17. Future large-aperture UVOIR space observatory: reference designs

    NASA Astrophysics Data System (ADS)

    Rioux, Norman; Thronson, Harley; Feinberg, Lee; Stahl, H. Phillip; Redding, Dave; Jones, Andrew; Sturm, James; Collins, Christine; Liu, Alice; Bolcar, Matthew

    2016-10-01

    Our joint NASA GSFC/JPL/MSFC and STScI study team has used community-developed science goals to derive mission needs, design parameters, notional instruments, and candidate mission architectures for a future large-aperture, noncryogenic UVOIR space observatory. We describe the feasibility assessment of system dynamic stability that supports coronagraphy. The observatory is in a Sun-Earth L2 orbit, which provides a stable thermal environment and excellent field of regard. Reference designs include a 36-segment 9.2-m aperture telescope that stows within a 5-m diameter launch vehicle fairing. This paper presents results from the latest cycle of integrated modeling through January 2016. The latest findings support the feasibility of secondary mirror support struts with a thickness on the order of an inch. Thin struts were found not to have a significant negative effect on wavefront error stability. Struts with a width as small as 1 in. may benefit some coronagraph designs by allowing more optical throughput.

  18. A Future Large-Aperture UVOIR Space Observatory: Study Overview

    NASA Astrophysics Data System (ADS)

    Postman, Marc; Thronson, Harley A.; Feinberg, Lee; Redding, David; Stahl, H. Philip

    2015-01-01

    The scientific drivers for very high angular resolution coupled with very high sensitivity and wavefront stability in the UV and optical wavelength regime have been well established. These include characterization of exoplanets in the habitable zones of solar type stars, probing the physical properties of the circumgalactic medium around z < 2 galaxies, and resolving stellar populations across a broad range of galactic environments. The 2010 NRC Decadal Survey and the 2013 NASA Science Mission Directorate 30-Year Roadmap identified a large-aperture UVOIR observatory as a priority future space mission. Our joint NASA GSFC/JPL/MSFC/STScI team has extended several earlier studies of the technology and engineering requirements needed to design and build a single filled aperture 10-meter class space-based telescope that can enable these ambitious scientific observations. We present here an overview of our new technical work including a brief summary of the reference science drivers as well as in-depth investigations of the viable telescope architectures, the requirements on thermal control and active wavefront control systems, and the range of possible launch configurations.

  19. A review of large aperture Schlieren photography technique

    NASA Astrophysics Data System (ADS)

    Xu, Song-bo; Xie, Yong-jun; Chen, Lei

    2016-01-01

    Schlieren photography is a visual process to display the flow of fluids of varying density. It is widely used in wind tunnel tests to photograph the flow of air around objects. To achieve schlieren images with high sensitivity and high resolution, and satisfy the requirements of the large-scale wind tunnel tests, it is urgent to develop schlieren photographers with large aperture primary mirrors. However, the application of large aperture primary mirrors may bring many challenges in the design of the schlieren system. First, the surface figure of large aperture primary mirrors is difficult to control so that the support structure may need more strategical design. Second, because the schlieren system works under some severe environments of the wind tunnel test including the air disturbance, wind-induced ground vibration and high ambient pressure, it has to withstand serious instability risks to ensure a good schlieren image quality. In this work, the current status of the development in the large aperture schlieren systems is reviewed. Several advanced methods, for example, active damping control technique, focal spot monitoring technique, 18-points whilffletree support technique, etc.., are introduced to deal with the challenges of the large aperture schlieren system. This work aims at improving the technical development of large aperture schlieren photographer, which may contribute to the acquisition of the high sensitive and high resolution schlieren images and the improvement of the testing capability in wind tunnel experiments.

  20. Highly uniform parallel microfabrication using a large numerical aperture system

    NASA Astrophysics Data System (ADS)

    Zhang, Zi-Yu; Zhang, Chen-Chu; Hu, Yan-Lei; Wang, Chao-Wei; Li, Jia-Wen; Su, Ya-Hui; Chu, Jia-Ru; Wu, Dong

    2016-07-01

    In this letter, we report an improved algorithm to produce accurate phase patterns for generating highly uniform diffraction-limited multifocal arrays in a large numerical aperture objective system. It is shown that based on the original diffraction integral, the uniformity of the diffraction-limited focal arrays can be improved from ˜75% to >97%, owing to the critical consideration of the aperture function and apodization effect associated with a large numerical aperture objective. The experimental results, e.g., 3 × 3 arrays of square and triangle, seven microlens arrays with high uniformity, further verify the advantage of the improved algorithm. This algorithm enables the laser parallel processing technology to realize uniform microstructures and functional devices in the microfabrication system with a large numerical aperture objective.

  1. Highly uniform parallel microfabrication using a large numerical aperture system

    SciTech Connect

    Zhang, Zi-Yu; Su, Ya-Hui E-mail: dongwu@ustc.edu.cn; Zhang, Chen-Chu; Hu, Yan-Lei; Wang, Chao-Wei; Li, Jia-Wen; Chu, Jia-Ru; Wu, Dong E-mail: dongwu@ustc.edu.cn

    2016-07-11

    In this letter, we report an improved algorithm to produce accurate phase patterns for generating highly uniform diffraction-limited multifocal arrays in a large numerical aperture objective system. It is shown that based on the original diffraction integral, the uniformity of the diffraction-limited focal arrays can be improved from ∼75% to >97%, owing to the critical consideration of the aperture function and apodization effect associated with a large numerical aperture objective. The experimental results, e.g., 3 × 3 arrays of square and triangle, seven microlens arrays with high uniformity, further verify the advantage of the improved algorithm. This algorithm enables the laser parallel processing technology to realize uniform microstructures and functional devices in the microfabrication system with a large numerical aperture objective.

  2. Zinc selenide-based large aperture photo-controlled deformable mirror.

    PubMed

    Quintavalla, Martino; Bonora, Stefano; Natali, Dario; Bianco, Andrea

    2016-06-01

    Realization of large aperture deformable mirrors with a large density of actuators is important in many applications, and photo-controlled deformable mirrors (PCDMs) represent an innovation. Herein we show that PCDMs are scalable realizing a 2-inch aperture device based on a polycrystalline zinc selenide (ZnSe) as the photoconductive substrate and a thin polymeric reflective membrane. ZnSe is electrically characterized and analyzed through a model that we previously introduced. The PCDM is then optically tested, demonstrating its capabilities in adaptive optics.

  3. Realization of a video-rate distributed aperture millimeter-wave imaging system using optical upconversion

    NASA Astrophysics Data System (ADS)

    Schuetz, Christopher; Martin, Richard; Dillon, Thomas; Yao, Peng; Mackrides, Daniel; Harrity, Charles; Zablocki, Alicia; Shreve, Kevin; Bonnett, James; Curt, Petersen; Prather, Dennis

    2013-05-01

    Passive imaging using millimeter waves (mmWs) has many advantages and applications in the defense and security markets. All terrestrial bodies emit mmW radiation and these wavelengths are able to penetrate smoke, fog/clouds/marine layers, and even clothing. One primary obstacle to imaging in this spectrum is that longer wavelengths require larger apertures to achieve the resolutions desired for many applications. Accordingly, lens-based focal plane systems and scanning systems tend to require large aperture optics, which increase the achievable size and weight of such systems to beyond what can be supported by many applications. To overcome this limitation, a distributed aperture detection scheme is used in which the effective aperture size can be increased without the associated volumetric increase in imager size. This distributed aperture system is realized through conversion of the received mmW energy into sidebands on an optical carrier. This conversion serves, in essence, to scale the mmW sparse aperture array signals onto a complementary optical array. The side bands are subsequently stripped from the optical carrier and recombined to provide a real time snapshot of the mmW signal. Using this technique, we have constructed a real-time, video-rate imager operating at 75 GHz. A distributed aperture consisting of 220 upconversion channels is used to realize 2.5k pixels with passive sensitivity. Details of the construction and operation of this imager as well as field testing results will be presented herein.

  4. Teaching and Research in Astronomy using Small Aperture Optical Telescopes

    NASA Astrophysics Data System (ADS)

    Pandey, S. K.

    2006-08-01

    Small aperture (<1m, typically 20-50cm) optical telescopes with adequate back-end instrumentation (photometer, CCD camera and CCD spectrograph etc) can be used for spreading the joy and excitement of observational astronomy among postgraduate and research students in Colleges/. On the basis of over a decade's experience in observing with small optical telescopes it has been amply demonstrated that such a facility, which any University department can hope to procure and maintain, can be effectively used for teaching as well quality research. The Physics Department of Pt Ravishankar Shukla University at Raipur, India offers Astronomy & Astrophysics (A&A) as one of the specialization as a part of M Sc program in Physics. A set of observational exercises has been incorporated with a view to provide training in observations, analysis and interpretation of the astronomical data to the students. Observing facilities available in the department include 8"-14" aperture telescopes (CGE series from Celestron) equipped with the new-state-of-the-art backend instrumentation like Photometer, CCD Camera and also a CCD spectrograph. Observing facility of this kind is ideally suited for continuous monitoring of a variety of variable stars, and thus can provide valuable data for understanding the physics of stellar variability. This is especially true for a class of variable stars known as chromospherically active stars. The stars belonging to this class have variable light curves, and the most puzzling feature is that their light curves change year after year in a rather queerer way. A large fraction of these active stars are bright ones and, hence, the importance of small aperture telescope for collecting the much needed photometric data. For over a decade the research activity using 14" optical telescope is focused on photometric monitoring of well known as well suspected active stars. This together with spectroscopic data using observing facility at Indian Observatories has led

  5. Three-Dimensional Optical Trapping of a Plasmonic Nanoparticle using Low Numerical Aperture Optical Tweezers

    PubMed Central

    Brzobohatý, Oto; Šiler, Martin; Trojek, Jan; Chvátal, Lukáš; Karásek, Vítězslav; Paták, Aleš; Pokorná, Zuzana; Mika, Filip; Zemánek, Pavel

    2015-01-01

    It was previously believed that larger metal nanoparticles behave as tiny mirrors that are pushed by the light beam radiative force along the direction of beam propagation, without a chance to be confined. However, several groups have recently reported successful optical trapping of gold and silver particles as large as 250 nm. We offer a possible explanation based on the fact that metal nanoparticles naturally occur in various non-spherical shapes and their optical properties differ significantly due to changes in localized plasmon excitation. We demonstrate experimentally and support theoretically three-dimensional confinement of large gold nanoparticles in an optical trap based on very low numerical aperture optics. We showed theoretically that the unique properties of gold nanoprisms allow an increase of trapping force by an order of magnitude at certain aspect ratios. These results pave the way to spatial manipulation of plasmonic nanoparticles using an optical fibre, with interesting applications in biology and medicine. PMID:25630432

  6. NST: Thermal Modeling for a Large Aperture Solar Telescope

    NASA Astrophysics Data System (ADS)

    Coulter, Roy

    2011-05-01

    Late in the 1990s the Dutch Open Telescope demonstrated that internal seeing in open, large aperture solar telescopes can be controlled by flushing air across the primary mirror and other telescope structures exposed to sunlight. In that system natural wind provides a uniform air temperature throughout the imaging volume, while efficiently sweeping heated air away from the optics and mechanical structure. Big Bear Solar Observatory's New Solar Telescope (NST) was designed to realize that same performance in an enclosed system by using both natural wind through the dome and forced air circulation around the primary mirror to provide the uniform air temperatures required within the telescope volume. The NST is housed in a conventional, ventilated dome with a circular opening, in place of the standard dome slit, that allows sunlight to fall only on an aperture stop and the primary mirror. The primary mirror is housed deep inside a cylindrical cell with only minimal openings in the side at the level of the mirror. To date, the forced air and cooling systems designed for the NST primary mirror have not been implemented, yet the telescope regularly produces solar images indicative of the absence of mirror seeing. Computational Fluid Dynamics (CFD) analysis of the NST primary mirror system along with measurements of air flows within the dome, around the telescope structure, and internal to the mirror cell are used to explain the origin of this seemingly incongruent result. The CFD analysis is also extended to hypothetical systems of various scales. We will discuss the results of these investigations.

  7. Metrology measurements for large-aperture VPH gratings

    NASA Astrophysics Data System (ADS)

    Zheng, Jessica R.; Gers, Luke; Heijmans, Jeroen

    2013-09-01

    The High Efficiency and Resolution Multi Element Spectrograph (HERMES) for the Australian Astronomical Observatory (AAO) uses four large aperture, high angle of incidence volume phase holographic gratings (VPHG) for high resolution `Galactic archaeology' spectroscopy. The large clear aperture, the high diffraction efficiency, the line frequency homogeneity, and mosaic alignment made manufacturing and testing challenging. We developed new metrology systems at the AAO to verify the performance of these VPH gratings. The measured diffraction efficiencies and line frequency of the VPH gratings received so far meet the vendor's provided data. The wavefront quality for the Blue VPH grating is good but the Green and Red VPH gratings need to be post polishing.

  8. Large Aperture, Scanning, L-Band SAR

    NASA Technical Reports Server (NTRS)

    Moussessian, Alina; Del Castillo, Linda; Bach, Vinh; Grando, Maurio; Quijano, Ubaldo; Smith, Phil; Zawadzki, Mark

    2011-01-01

    We have developed the first L-band membrane-based active phased array. The antenna is a 16x16 element patch array with dimensions of 2.3mx2.6m. The array uses membrane-compatible Transmit/Receive (T/R) modules for electronic beam steering. We will discuss the antenna design, the fabrication of this large array, the T/R module development, the signal distribution approach and the measured results of the array.

  9. Large Aperture, Scanning, L-Band SAR

    NASA Technical Reports Server (NTRS)

    Moussessian, Alina; DelCastillo, Linda; Bach, Vinh; Grando, Maurio; Quijano, Ubaldo; Smith, Phil; Zawadzki, Mark

    2011-01-01

    We have developed the first L-band membrane-based active phased array. The antenna is a 16x16 element patch array with dimensions of 2.3mx2.6m. The array uses membrane-compatible Transmit/Receive (T/R) modules for electronic beam steering. We will discuss the antenna design, the fabrication of this large array, the T/R module development, the signal distribution approach and the measured results of the array

  10. Large Aperture, Scanning, L-Band SAR

    NASA Technical Reports Server (NTRS)

    Moussessian, Alina; Del Castillo, Linda; Bach, Vinh; Grando, Maurio; Quijano, Ubaldo; Smith, Phil; Zawadzki, Mark

    2011-01-01

    We have developed the first L-band membrane-based active phased array. The antenna is a 16x16 element patch array with dimensions of 2.3mx2.6m. The array uses membrane-compatible Transmit/Receive (T/R) modules for electronic beam steering. We will discuss the antenna design, the fabrication of this large array, the T/R module development, the signal distribution approach and the measured results of the array.

  11. Large Aperture, Scanning, L-Band SAR

    NASA Technical Reports Server (NTRS)

    Moussessian, Alina; DelCastillo, Linda; Bach, Vinh; Grando, Maurio; Quijano, Ubaldo; Smith, Phil; Zawadzki, Mark

    2011-01-01

    We have developed the first L-band membrane-based active phased array. The antenna is a 16x16 element patch array with dimensions of 2.3mx2.6m. The array uses membrane-compatible Transmit/Receive (T/R) modules for electronic beam steering. We will discuss the antenna design, the fabrication of this large array, the T/R module development, the signal distribution approach and the measured results of the array

  12. Adaptive Techniques for Large Space Apertures.

    DTIC Science & Technology

    1980-03-01

    GP Anitern, 200l de or,~,’rn, receiner/ proceso 1"’ - requires enternal !titude deter- minationr such as a star tracker Increased mechanizatio’ Sensor...control systems into one unit; namely, a fine pointing control using the gimbal rates as the control variables while maintaining constant rotor speeds...CMG mode), and a coarse control for large maneuvers using the rotor speeds as the control variables and locking the gimbals (RW mode). The simultaneous

  13. Millimeter Wave Applications of Large Aperture Systems

    DTIC Science & Technology

    1980-02-01

    unit step impulse ................. 89 5-8 Truss/tower model. Joints identification numbers ............... 91 5-9 z-displacement (m) histories for the...tip joint 801 displacements for 1 cycle steady-state response to harmonic excitation (15 N at 10 Hz) ................ 101 6-1 Elliptic torus 30 x 60 m...freedom (DOF) -o a reasonable level, the large platform was modelled with axial members whereby only three DOF’s are present nat each joint . Although

  14. Off-axis multipass amplifier as a large aperture driver stage for fusion lasers.

    PubMed

    Murray, J E; Downs, D C; Hunt, J T; Hermes, G L; Warren, W E

    1981-03-01

    A multipass amplifier configuration is described which has potential as a large aperture, high gain driver stage for fusion laser systems. We avoid the present limitations of large aperture switches by using an off-angle geometry that does not require an optical switch. The saturated gain characteristics of this multipass amplifier are optimized numerically. Three potential problems are investigated experimentally, self-lasing, output beam quality, and amplified spontaneous emission output. The results indicate comparable cost for comparable performance to a linear chain, with some operational advantage for the multipass driver stage.

  15. Operational aspects of the Main Injector large aperture quadrupole (WQB)

    SciTech Connect

    Chou, W.; Bartelson, L.; Brown, B.; Capista, D.; Crisp, J.; DiMarco, J.; Fitzgerald, J.; Glass, H.; Harding, D.; Johnson, D.; Kashikhin, V.; /Fermilab

    2007-06-01

    A two-year Large Aperture Quadrupole (WQB) Project was completed in the summer of 2006 at Fermilab. [1] Nine WQBs were designed, fabricated and bench-tested by the Technical Division. Seven of them were installed in the Main Injector and the other two for spares. They perform well. The aperture increase meets the design goal and the perturbation to the lattice is minimal. The machine acceptance in the injection and extraction regions is increased from 40{pi} to 60{pi} mm-mrad. This paper gives a brief report of the operation and performance of these magnets. Details can be found in Ref [2].

  16. Imaging with Concave Large-Aperture Therapeutic Ultrasound Arrays Using Conventional Synthetic-Aperture Beamforming

    PubMed Central

    Wan, Yayun; Ebbini, Emad S.

    2009-01-01

    Several dual-mode ultrasound array (DMUA) systems are being investigated for potential use in image-guided surgery. In therapeutic mode, DMUAs generate pulsed or continuous-wave (CW) high-intensity focused ultrasound (HIFU) beams capable of generating localized therapeutic effects within the focal volume. In imaging mode, pulse-echo data can be collected from the DMUA elements to obtain B-mode images or other forms of feedback on the state of the target tissue before, during, and after the application of the therapeutic HIFU beam. Therapeutic and technological constraints give rise to special characteristics of therapeutic arrays. Specifically, DMUAs have concave apertures with low f-number values and are typically coarsely sampled using directive elements. These characteristics necessitate pre- and post-beamforming signal processing of echo data to improve the spatial and contrast resolution and maximize the image uniformity within the imaging field of view (IxFOV). We have recently developed and experimentally validated beamforming algorithms for concave large-aperture DMUAs with directive elements. Experimental validation was performed using a 1 MHz, 64-element, concave spherical aperture with 100 mm radius of curvature. The aperture was sampled in the lateral direction using elongated elements 1−λ×33.3‒ with 1.333‒−λ center-to-center spacing (λ is the wavelength). This resulted in f-number values of 0.8 and 2 in the azimuth and elevation directions, respectively. In this paper, we present a new DMUA design approach based on different sampling of the shared concave aperture to improve image quality while maintaining therapeutic performance. A pulse-wave (PW) simulation model using a modified version of the Field II program is used in this study. The model is used in generating pulse-echo data for synthetic-aperture (SA) beamforming for forming images of a variety of targets, e.g., wire arrays and speckle-generating cyst phantoms. To provide

  17. Imaging with concave large-aperture therapeutic ultrasound arrays using conventional synthetic-aperture beamforming.

    PubMed

    Wan, Yayun; Ebbini, Emad S

    2008-08-01

    Several dual-mode ultrasound array (DMUA) systems are being investigated for potential use in image- guided surgery. In therapeutic mode, DMUAs generate pulsed or continuous-wave (CW) high-intensity focused ultrasound (HIFU) beams capable of generating localized therapeutic effects within the focal volume. In imaging mode, pulse-echo data can be collected from the DMUA elements to obtain B-mode images or other forms of feedback on the state of the target tissue before, during, and after the application of the therapeutic HIFU beam. Therapeutic and technological constraints give rise to special characteristics of therapeutic arrays. Specifically, DMUAs have concave apertures with low f-number values and are typically coarsely sampled using directive elements. These characteristics necessitate pre- and post-beamforming signal processing of echo data to improve the spatial and contrast resolution and maximize the image uniformity within the imaging field of view (IxFOV). We have recently developed and experimentally validated beamforming algorithms for concave large-aperture DMUAs with directive elements. Experimental validation was performed using a 1 MHz, 64-element, concave spherical aperture with 100 mm radius of curvature. The aperture was sampled in the lateral direction using elongated elements 1-lambda x 33.3-lambda with 1.333-lambda center-to-center spacing (lambda is the wavelength). This resulted in f-number values of 0.8 and 2 in the azimuth and elevation directions, respectively. In this paper, we present a new DMUA design approach based on different sampling of the shared concave aperture to improve image quality while maintaining therapeutic performance. A pulse-wave (PW) simulation model using a modified version of the Field II program is used in this study. The model is used in generating pulse-echo data for synthetic-aperture (SA) beamforming for forming images of a variety of targets, e.g., wire arrays and speckle-generating cyst phantoms. To

  18. Inter-aperture correlation in MIMO free space optical systems

    NASA Astrophysics Data System (ADS)

    Özbilgin, Tuğba; Koca, Mutlu

    2015-10-01

    We present a unified framework for determining the inter-aperture separations in multiple-input-multiple-output (MIMO) free space optical (FSO) systems such that the transmitter-receiver paths are resolvable. The analysis framework is also useful in determining the amount of spatial correlation for a given set of system configuration parameters and aperture separations. It is applicable to both point apertures and also apertures with larger diameters and can be used at both transmit and receive arrays. We show that the results obtained via theoretical derivations are in good agreement with those in the literature obtained via measurements or simulations. The theoretical calculations reveal that even under strong turbulence conditions and very long link distances, aperture separations at the order of a few tens of centimeters are sufficient to have resolvable paths with independent fading gains. Furthermore, the channel correlations increase relatively slowly with decreasing inter-aperture separations which are below these values. We also provide design guidelines to obtain resolvable paths for several commonly used system configurations.

  19. Optical design of a synthetic aperture ladar antenna system

    NASA Astrophysics Data System (ADS)

    Cao, Changqing; Zeng, Xiaodong; Zhao, Xiaoyan; Liu, Huanhuan; Man, Xiangkun

    2008-03-01

    The spatial resolution of a conventional imaging LADAR system is constrained by the diffraction limit of the telescope aperture. The purpose of this work is to investigate Synthetic Aperture Imaging LADAR (SAIL), which employs aperture synthesis with coherent laser radar to overcome the diffraction limit and achieve fine-resolution, long range, two-dimensional imaging with modest aperture diameters. According to the demands of the Synthetic Aperture LADAR (SAL), the key techniques are analyzed briefly. The preliminary design of the optical antenna is also introduced in this paper. We investigate the design method and relevant problems of efficient optical antenna that are required in SAL. The design is pursued on the basis of the same method as is used at microwave frequency. The method is based on numerical analysis and the error values obtained by present manufacturing technology. According to the requirement to SAL with the trial of little size, light mass, low cost and high image quality, the result by ZEMAX will result.

  20. Engineering Specification for Large-aperture UVO Space Telescopes Derived from Science Requirements

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip; Arnold, William; Bevan, Ryan M.; Smith, W. Scott.; Kirk, Charles S.; Postman, Mark

    2013-01-01

    An advanced large aperture UV/optical UVO space telescope is required for the next generation of astrophysics and exoplanet science. The science requirements of proposed exoplanet and astrophysics missions were used to determine the encircled energy, point spread function stability and thermal environment requirements. These requirements then determine the optical wavefront specification for potential telescope assemblies which can fit inside current and planned launch vehicles. The optical wavefront specification becomes the top level of the error budget that is split into various sources that control the structural, thermal and optical design.

  1. Thermal control analysis of a primary mirror for large-aperture telescope

    NASA Astrophysics Data System (ADS)

    Tan, Yufeng; Wang, Jihong; Ren, Ge; Xie, Zongliang; He, Bi

    2017-07-01

    Extraneous thermal loads on the primary mirror of a large-aperture telescope directly influence the optical performance of the telescope through temperature gradients within the mirror and thermal boundary layer at the face sheet. In this paper, we propose a new thermal control system consisting of a flushing and sucking system for eliminating the excessive heat of a primary mirror. First, a 2.8 m-aperture lightweighted primary mirror is fabricated. Second, a thermo-optic analysis using finite element analysis is conducted in natural and forced convection. Finally, the optical performance denoted by Zernike polynomials with and without our proposed thermal control system is evaluated and examined. The comparative results reveal that the image quality of the primary mirror in forced convection is significantly enhanced with obvious reduction of optical surface distortion, thereby demonstrating the effectiveness of our proposed thermal control system.

  2. Design of wavefront coding optical system with annular aperture

    NASA Astrophysics Data System (ADS)

    Chen, Xinhua; Zhou, Jiankang; Shen, Weimin

    2016-10-01

    Wavefront coding can extend the depth of field of traditional optical system by inserting a phase mask into the pupil plane. In this paper, the point spread function (PSF) of wavefront coding system with annular aperture are analyzed. Stationary phase method and fast Fourier transform (FFT) method are used to compute the diffraction integral respectively. The OTF invariance is analyzed for the annular aperture with cubic phase mask under different obscuration ratio. With these analysis results, a wavefront coding system using Maksutov-Cassegrain configuration is designed finally. It is an F/8.21 catadioptric system with annular aperture, and its focal length is 821mm. The strength of the cubic phase mask is optimized with user-defined operand in Zemax. The Wiener filtering algorithm is used to restore the images and the numerical simulation proves the validity of the design.

  3. The Balloon-borne Large Aperture Submillimeter Telescope: BLAST

    NASA Astrophysics Data System (ADS)

    Truch, Matthew D. P.; Ade, P. A. R.; Bock, J. J.; Chapin, E. L.; Chung, J.; Devlin, M. J.; Dicker, S.; Griffin, M.; Gundersen, J. O.; Halpern, M.; Hargrave, P. C.; Hughes, D. H.; Klein, J.; MacTavish, C. J.; Marsden, G.; Martin, P. G.; Martin, T. G.; Mauskopf, P.; Netterfield, C. B.; Olmi, L.; Pascale, E.; Patanchon, G.; Rex, M.; Scott, D.; Semisch, C.; Thomas, N. E.; Tucker, C.; Tucker, G. S.; Viero, M. P.; Wiebe, D. V.

    2009-01-01

    The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) is a suborbital surveying experiment designed to study the evolutionary history and processes of star formation in local galaxies (including the Milky Way) and galaxies at cosmological distances. The BLAST continuum camera, which consists of 270 detectors distributed between three arrays, observes simultaneously in broadband (30%) spectral windows at 250, 350, and 500 microns. The optical design is based on a 2 m diameter telescope, providing a diffraction-limited resolution of 30" at 250 microns. The gondola pointing system enables raster mapping of arbitrary geometry, with a repeatable positional accuracy of 30"; postflight pointing reconstruction to <5" rms is achieved. The onboard telescope control software permits autonomous execution of a preselected set of maps, with the option of manual override. On this poster, we describe the primary characteristics and measured in-flight performance of BLAST. BLAST performed a test flight in 2003 and has since made two scientifically productive long-duration balloon flights: a 100 hour flight from ESRANGE (Kiruna), Sweden to Victoria Island, northern Canada in 2005 June; and a 250 hour, circumpolar flight from McMurdo Station, Antarctica in 2006 December. The BLAST collaboration acknowledges the support of NASA through grants NAG5-12785, NAG5-13301, and NNGO-6GI11G, the Canadian Space Agency (CSA), the Science and Technology Facilities Council (STFC), Canada's Natural Sciences and Engineering Research Council (NSERC), the Canada Foundation for Innovation, the Ontario Innovation Trust, the Puerto Rico Space Grant Consortium, the Fondo Institucional para la Investigacion of the University of Puerto Rico, and the National Science Foundation Office of Polar Programs.

  4. Mission definition for a large-aperture microwave radiometer spacecraft

    NASA Technical Reports Server (NTRS)

    Keafer, L. S., Jr.

    1981-01-01

    An Earth-observation measurements mission is defined for a large-aperture microwave radiometer spacecraft. This mission is defined without regard to any particular spacecraft design concept. Space data application needs, the measurement selection rationale, and broad spacecraft design requirements and constraints are described. The effects of orbital parameters and image quality requirements on the spacecraft and mission performance are discussed. Over the land the primary measurand is soil moisture; over the coastal zones and the oceans important measurands are salinity, surface temperature, surface winds, oil spill dimensions and ice boundaries; and specific measurement requirements have been selected for each. Near-all-weather operation and good spatial resolution are assured by operating at low microwave frequencies using an extremely large aperture antenna in a low-Earth-orbit contiguous mapping mode.

  5. Applications of optical upconversion to sparse aperture millimeter-wave imaging

    NASA Astrophysics Data System (ADS)

    Schuetz, C. A.; Mirotznik, M. S.; Shi, S.; Schneider, G. J.; Murakowski, J.; Prather, D. W.

    2005-11-01

    Passive millimeter-wave imagers have shown significant potential for use in applications that require penetration through atmospheric obscurations such a fog and smoke. However, the large apertures required to achieve sufficient diffraction-limited resolution in such systems often prohibit their use for many applications. One possible technique to circumvent this limitation is to use sparse-aperture imaging techniques. To date, such systems have not been realized because they require a high number of phase-sensitive, low-noise detectors spread over a large physical area. Collection and correlation processing of the data from this large array of sensors has not been practical using available technologies. Herein, we present the potential of optical upconversion detectors for sparse aperture imaging. The optical signals generated in such detectors preserve the phase information of the detected signal up until photodetection and may be easily routed to a central processor using low-loss optical fiber. Potential architectures for sparse aperture imagers using optical upconversion are discussed and compared to more traditional down-converted approaches. In addition, experimental results demonstrating the viability of such imagers are presented.

  6. Dual-aperture optical system for infrared camera

    NASA Astrophysics Data System (ADS)

    Lee, Kim-Hwee

    1999-11-01

    Conventional IR optical systems with high magnification and switchable FOBs suffer form strong unwanted Narcissus effect. This is mainly caused by retro-reflections from the objective lens back to the detector plane. In this project, a new dual aperture optical configuration has been developed to reduce substantially the Narcissus effect while maintaining good optical performance. A design example is presented in this paper. The relative Narcissus Induced Temperature is reduced from about 1.4 degree C to about 0.1 degree C, thus enhancing the detection range of the IR system.

  7. Large aperture millimeter/submillimeter telescope: which is more cost-effective, aperture synthesis telescope versus large single dish telescope?

    NASA Astrophysics Data System (ADS)

    Iguchi, Satoru; Saito, Masao

    2016-07-01

    The Atacama Large Millimeter/submillimeter Array (ALMA) consists of 66 antennas with the aperture equivalent to a 91-m diameter antenna. The Green Bank Telescope (GBT) is the world's largest, 100-m diameter telescope in the wavelength range of 3 mm to 30 cm. The Large Millimeter Telescope (LMT) will be the world's largest, 50-m diameter, steerable millimeter-wavelength telescope. The Cerro Chajnantor Atacama Telescope (CCAT) will be the world's largest, 25-m diameter, submillimeter-wavelength telescope. We will investigate advantages and disadvantages of both the aperture synthesis telescope and the large single-dish telescope taking the cost effectiveness into consideration, and will propose the design of antenna structure for a future telescope project at millimeter and submillimeter wavelengths.

  8. Obtaining Crosswind from Single-Aperture Optical Scintillometers

    NASA Astrophysics Data System (ADS)

    van Dinther, D.; Hartogensis, O. K.

    2010-09-01

    A scintillometer is a device that consist of a transmitter and receiver. The receiver records intensity fluctuations of the electromagnetic beam emitted at optical or microwave wavelengths by the transmitter. These fluctuations are caused by refraction of the beam upon its passage through the turbulent surface layer. An increasingly popular application of scintillometry is to estimate the area-averaged surface fluxes from these raw measurements following scintillometer theory (Tatarskii, 1961) relating the raw intensity measurements to the structure parameter of the refractive index, Cn2 and Monin-Obukhov similarity theory that relates structure parameters to surface fluxes (Meijninger et al., 2002). A less known application of scintillometry is the estimation of the crosswind, i.e. the wind perpendicular to the scintillometer path. Past research on this issue focused on multiple aperture scintillometers that use the time delay between the turbulence signals of the displaced apertures to estimate the crosswind (Andreas, 2000, Poggio et al., 2000 and Furger et al., 2001,). The goal of this study is to explore a method to obtain the crosswind from single aperture scintillometers through spectral analysis of the raw scintillometer signal. In theory the scintillometer spectrum shows an inflection at the transition of the refractive and absorption part of the spectrum. The transition frequency (fC2) is related to the ratio of the crosswind and the diameter of the receiver and transmitter (Nieveen et al., 1998) via fc2 = -u-- 1.25D where u is the crosswind speed and D the diameter of the scintillometer. Limitation of the method is that it only works properly when the crosswind is constant, i.e. with a horizontal scintillometer path, no time variation and no spatial variations of the crosswind. The prescribed method to obtain the crosswind is examined with LITFASS-2009 (Germany) and Haarweg (The Netherlands) datasets. At LITFASS-2009 different optical and microwave

  9. Comparison of large aperture telescopes with parabolic and spherical primaries

    NASA Technical Reports Server (NTRS)

    Korsch, D.

    1986-01-01

    Quasi-Cassegrain-type four-mirror telescopes are compared to conventional two-mirror Cassegrain telescopes for use as high performance, very large aperture space telescopes. Spherical and parabolic primaries with continuous as well as segmented surfaces are considered. Imaging characteristics and misalignment sensitivities serve as the principal criteria of comparison. The evaluation shows that parabolic primaries yield superior wide-field performance, whereas spherical primaries hold distinct advantages regarding manufacturability and regarding certain alignment aspects in the case of segmentation.

  10. Low-stress mounting configuration design for large aperture laser transport mirror

    NASA Astrophysics Data System (ADS)

    Zhang, Zheng; Quan, Xusong; Yao, Chao; Wang, Hui

    2016-10-01

    TM1-6S1 large aperture laser transport mirror is a crucial optical unit of high power solid-state laser in the Inertial Confinement Fusion (ICF) facility. This article focuses on the low-stress and precise mounting method of large-aperture mirror. Based on the engineering practice of SG-III, the state-of-the-art and key problems of current mounting configuration are clarified firstly. Subsequently, a brand new low-stress mounting configuration with flexure supports is proposed. Opto-mechanical model of the mirror under mounting force is built up with elastic mechanics theory. Further, numerical methods and field tests are employed to verify the favorable load uniform capacity and load adjust capacity of flexure supports. With FEM, the relation between the mounting force from new configuration and the mirror surface distortion (wavefront error) is clarified. The novel mounting method of large aperture optics could be not only used on this laser transport mirror, but also on the other transmission optics and large crystals in ICF facilities.

  11. A Future Large-Aperture UVOIR Space Observatory: Reference Designs

    NASA Technical Reports Server (NTRS)

    Thronson, Harley; Rioux, Norman; Feinberg, Lee; Stahl, H. Philip; Redding, Dave; Jones, Andrew; Sturm, James; Collins, Christine; Liu, Alice

    2015-01-01

    Our joint NASA GSFC/JPL/MSFC/STScI study team has used community-provided science goals to derive mission needs, requirements, and candidate mission architectures for a future large-aperture, non-cryogenic UVOIR space observatory. We describe the feasibility assessment of system thermal and dynamic stability for supporting coronagraphy. The observatory is in a Sun-Earth L2 orbit providing a stable thermal environment and excellent field of regard. Reference designs include a 36-segment 9.2 m aperture telescope that stows within a five meter diameter launch vehicle fairing. Performance needs developed under the study are traceable to a variety of reference designs including options for a monolithic primary mirror.

  12. A future large-aperture UVOIR space observatory: reference designs

    NASA Astrophysics Data System (ADS)

    Rioux, Norman; Thronson, Harley; Feinberg, Lee; Stahl, H. Philip; Redding, Dave; Jones, Andrew; Sturm, James; Collins, Christine; Liu, Alice

    2015-09-01

    Our joint NASA GSFC/JPL/MSFC/STScI study team has used community-provided science goals to derive mission needs, requirements, and candidate mission architectures for a future large-aperture, non-cryogenic UVOIR space observatory. We describe the feasibility assessment of system thermal and dynamic stability for supporting coronagraphy. The observatory is in a Sun-Earth L2 orbit providing a stable thermal environment and excellent field of regard. Reference designs include a 36-segment 9.2 m aperture telescope that stows within a five meter diameter launch vehicle fairing. Performance needs developed under the study are traceable to a variety of reference designs including options for a monolithic primary mirror.

  13. Subaperture stitching interferometer for large optics

    NASA Astrophysics Data System (ADS)

    Zeng, Shengyue; Dai, Yifan; Chen, Shanyong

    2009-05-01

    Ultra-high precision measurement of the form is critical in deterministic machining of optical components. It is generally accomplished with an interferometer. However, a standard interferometer is incompetent for large convex aspherical surfaces or those with large relative apertures. Hence subaperture stitching interferometry was proposed to extend the vertical range of measurement and enhance the lateral resolution, based on the idea of "stitching pieces together". This paper presents a prototype design for subaperture stitching interferometer (SASI) for large optics. It applies to large flats (clear aperture<700mm), large concave spherical or aspherical surfaces (clear aperture<350mm, 1:2aperture<1:1). Firstly, three designs are compared to choose an appropriate layout of the optical path for testing large optics. Then the multi-axis mechanical design is introduced in detail. The kinematical model of SASI is built according to the kinematics of open-loop robots. It helps to determine the stroke, resolution and accuracy of each axis. The advantages of the iterative subaperture stitching algorithm, e.g., no requirements of precise prior knowledge of subaperture alignment error, considerably facilitate the mechanical design.

  14. Silicon Powder Filters for Large-Aperture Cryogenic Receivers

    NASA Astrophysics Data System (ADS)

    Boone, Fletcher; Essinger-Hileman, T.; Bennett, C. L.; Marriage, T.; Xu, Z.

    2014-01-01

    Upcoming experiments probing for the existence of B-mode polarization in the cosmic microwave background (CMB) will require large arrays of background-limited detectors. This will necessitate the use of cryogenic receivers with large-aperture vacuum windows and correspondingly large low-pass infrared-blocking filters to minimize thermal load. Large-diameter filters composed of absorptive dielectrics are difficult to conductively cool adequately, and thus tend to heat up and re-radiate towards the focal plane. Reflective metal-mesh filters are challenging to manufacture at such large apertures and with feature sizes small enough to effectively block 300K thermal radiation. In order to overcome these difficulties, we have developed a novel type of thermal filter that scatters, rather than reflects or absorbs, unwanted infrared radiation. Comprised of ultra-pure silicon powder distributed within a polymethylpentene (PMP) substrate, these filters are not absorptive in the infrared while being transparent to microwaves, and are comparatively straightforward to produce. By adjusting the size of the silicon particles, the frequency cut-off of these low-pass filters is fully tunable. Small scale (70mm diameter, 3mm thickness) prototypes have exhibited <10% transmission throughout the infrared spectrum and <1% transmission at the peak of the 300K blackbody spectrum, while maintaining an estimated 97% transmission in the microwave regime.

  15. Study of electron beam uniformity in large-area multi-aperture diode with arc plasma cathode

    NASA Astrophysics Data System (ADS)

    Kandaurov, I. V.; Kurkuchekov, V. V.; Trunev, Yu A.

    2017-05-01

    The use of plasma emission cathode in the conjunction with a multiple apertured electron optical system (EOS) is promising for the multi-MW class electron beams of a large cross-sectional area. In a multi-aperture source, the beam parameters could be raised simply due to increase of the number of apertures (i.e. an effective emission area), if a uniformity of the electron emission over a large-area plasma cathode is ensured. In the presented paper, the cross-sectional distribution of the emission current density was investigated using the X-ray diagnostic technique for two versions of the diode-type EOS, with electrodes performed as flat molybdenum “grids”. The first one had 241 apertures arranged hexagonally inside a circle with a diameter of 8.3 cm and the second had 499 apertures within a circle of 11.8cm diameter. The emission plasma is produced using a single arc-discharge plasma generator placed on the axis at 20 cm from the EOS. It was demonstrated that multi-aperture systems with a single on-axis plasma generator can be effectively employed to obtain large-area beams, even in the presence of the guiding magnetic field. All apertures are emitting in the 499-apertured EOS. The beam current density is quite uniform up to the radius 2.5cm and gradually decreases to the periphery.

  16. Annular sub-aperture stitching interferometry testing for large-caliber aspheric

    NASA Astrophysics Data System (ADS)

    Wu, Pengfei; Yang, Shuming; Sun, Lin; Zhao, Pu; Jiang, Zhuangde

    2016-09-01

    An annular sub-aperture stitching interferometry testing is proposed for large-caliber aspheric lens testing, expanding the dynamic range of the interferometer, broadening the scope of the measurement, and reducing the cost of the measurement to a large extent without the use of compensating elements. The large-caliber aspheric is divided into several annular sub-apertures, and there are some overlapping areas between each two adjacent sub-apertures. When testing, the test aspheric is moved along the optical axis according to path planning so that the reference spherical shape and the test aspheric interest at points of common tangency to reduce the fringe density of the sub-aperture. However, in the process of moving the test optic, six DOF (degrees of freedom) misalignment errors will occur. According to the rigid body kinematics theory, the misalignment error separation model is established so that the misalignment factors can be calculated by the information of each overlapping regions. Then all sub-apertures are unified to the same reference with proper algorithm, and subsequently, misalignment error of the reference is removed by Zernike polynomial fitting, and the whole surface error is recovered. Simulation results are shown to demonstrate the feasibility of the method we developed. By analyzing the influence of the six DOF on the stitching result, the most important factor is obtained, and some measures are taken, that is, a measurement system combining two interferometers is designed, one of which is to measure the departures between the reference and the aspheric, and another to test the piston errors to be transmitted to the control system to improve the accuracy.

  17. The development of large-aperture test system of infrared camera and visible CCD camera

    NASA Astrophysics Data System (ADS)

    Li, Yingwen; Geng, Anbing; Wang, Bo; Wang, Haitao; Wu, Yanying

    2015-10-01

    Infrared camera and CCD camera dual-band imaging system is used in many equipment and application widely. If it is tested using the traditional infrared camera test system and visible CCD test system, 2 times of installation and alignment are needed in the test procedure. The large-aperture test system of infrared camera and visible CCD camera uses the common large-aperture reflection collimator, target wheel, frame-grabber, computer which reduces the cost and the time of installation and alignment. Multiple-frame averaging algorithm is used to reduce the influence of random noise. Athermal optical design is adopted to reduce the change of focal length location change of collimator when the environmental temperature is changing, and the image quality of the collimator of large field of view and test accuracy are also improved. Its performance is the same as that of the exotic congener and is much cheaper. It will have a good market.

  18. Cavity-waveguide coupling through a large aperture

    SciTech Connect

    Wang, T.F.; Thode, L.E.; Cooper, R.K.

    1988-01-01

    In designing a high-power, single-feed rf-cavity, one needs to consider the field disturbance caused by the large coupling aperture between the cavity and the waveguide. In this paper, we present and approach for studying this kind of field disturbance for modes in the frequency domain by using the three-dimensional code MAFIA. We demonstrate that by judiciously choosing the boundary conditions at the appropriate location along the waveguide, one can model the cavity-waveguide system by a closed boundary system and reduce the computation time significantly. 5 refs., 7 figs.

  19. Extracting spatial information from large aperture exposures of diffuse sources

    NASA Technical Reports Server (NTRS)

    Clarke, J. T.; Moos, H. W.

    1981-01-01

    The spatial properties of large aperture exposures of diffuse emission can be used both to investigate spatial variations in the emission and to filter out camera noise in exposures of weak emission sources. Spatial imaging can be accomplished both parallel and perpendicular to dispersion with a resolution of 5-6 arc sec, and a narrow median filter running perpendicular to dispersion across a diffuse image selectively filters out point source features, such as reseaux marks and fast particle hits. Spatial information derived from observations of solar system objects is presented.

  20. Development of Large-Aperture, Light-Weight Fresnel Lenses for Gossamer Space Telescopes

    SciTech Connect

    Sham, D; Hyde, R; Weisberg, A; Early, J; Rushford, M; Britten, J

    2002-04-29

    In order to examine more distant astronomical objects, with higher resolution, future space telescopes require objectives with significantly larger aperture than presently available. NASA has identified a progression in size from the 2.4m aperture objective currently used in the HUBBLE space telescope[l,2], to 25m and greater in order to observe, e.g., extra-solar planets. Since weight is a crucial factor for any object sent into space, the relative weight of large optics over a given area must be reduced[3]. The areal mass density of the primary mirror for the Hubble space telescope is {approx}200 kg/m{sup 2}. This is expected to be reduced to around 15 kg/m{sup 2} for the successor to Hubble--the next generation space telescope (NGST)[4]. For future very large aperture telescopes needed for extra-solar planet detection, the areal mass density must be reduced even further. For example, the areal mass density goal for the Gossamer space telescopes is < 1 kg/m{sup 2}. The production of lightweight focusing optics at >10m size is also an enabling technology for many other applications such as Earth observation, power beaming, and optical communications.

  1. Research on the support structure of the primary mirror of large-aperture telescope

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Zhang, Jingxu

    2007-12-01

    Large-aperture telescope can be used in surveying battlefield, researching landform, searching object, real-time monitoring, imaging, detecting and identifying spatial targets and so on. A large-aperture telescope for achieving high resolution power is designed to monitor spatial target and image in real time. Real-time monitoring plays an important role in military conflicts. The orbit parameter of object, quantity, geometrical shape parameter and so on can be obtained by detect spatial target. With the development of optical technology, people require larger aperture in optics-electronic (O-E) system. By increasing optical aperture, the ability of collecting light and resolution power in the system can be enhanced. But the support structure of the primary mirror of large-aperture telescope will be a very difficult problem. With the increase of primary mirror aperture, the weight of the primary mirror will become larger than before. The root mean square (rms) of the primary mirror is affected by many factors, such as deadweight, deformation of heat, environment and so on. Due to the primary mirror of telescope is an important component of telescope system. By reducing the weight of primary mirror, precision of the system is ensured. During the designing phase, one can consider the supporting project of the primary mirror synthetically and analyze it roundly according to technical requirement of optical system and the effect factors. The final structural design can be reasonable. In an astronomical telescope, the surface of reflector is an important part for collecting dark radiation of celestial bodies. Its surface shape will have an effect on collecting efficiency of telescope radiant energy directly. So the rms must be very high. Optical system of large aperture, small wavelength and small focus can receive maximal light intensity. For ground-based optical astronomical telescope, the design proposed in the paper can satisfy the requirement of the possible

  2. Large-aperture MOEMS Fabry-Perot interferometer for miniaturized spectral imagers

    NASA Astrophysics Data System (ADS)

    Rissanen, Anna; Langner, Andreas; Viherkanto, Kai; Mannila, Rami

    2015-02-01

    VTT's optical MEMS Fabry-Perot interferometers (FPIs) are tunable optical filters, which enable miniaturization of spectral imagers into small, mass producible hand-held sensors with versatile optical measurement capabilities. FPI technology has also created a basis for various hyperspectral imaging instruments, ranging from nanosatellites, environmental sensing and precision agriculture with UAVs to instruments for skin cancer detection. Until now, these application demonstrations have been mostly realized with piezo-actuated FPIs fabricated by non-monolithical assembly method, suitable for achieving very large optical apertures and with capacity to small-to-medium volumes; however large-volume production of MEMS manufacturing supports the potential for emerging spectral imaging applications also in large-volume applications, such as in consumer/mobile products. Previously reported optical apertures of MEMS FPIs in the visible range have been up to 2 mm in size; this paper presents the design, successful fabrication and characterization of MEMS FPIs for central wavelengths of λ = 500 nm and λ = 650 nm with optical apertures up to 4 mm in diameter. The mirror membranes of the FPI structures consist of ALD (atomic layer deposited) TiO2-Al2O3 λ/4- thin film Bragg reflectors, with the air gap formed by sacrificial polymer etching in O2 plasma. The entire fabrication process is conducted below 150 °C, which makes it possible to monolithically integrate the filter structures on other ICdevices such as detectors. The realized MEMS devices are aimed for nanosatellite space application as breadboard hyperspectral imager demonstrators.

  3. Large aperture interferometer with phase-conjugate self-reference beam

    NASA Technical Reports Server (NTRS)

    Howes, W. L.

    1986-01-01

    A large aperture self-referencing interferometer consisting of a Twyman-Green interferometer using a self-pumped phase conjugator in series with test section optics is described and experimentally demonstrated. This interferometer provides twice the fringe shift of a Mach-Zehnder (M-Z) interferometer for a given optical phase change induced within the test section. It also provides greater irradiance in the reference beam than does a similar series setup utilizing a M-Z interferometer incorporating a local reference beam. Whereas the ordinary interferometer records instantaneous conditions, the new one records overage conditions if a BaTiO3 crystal is used as the phase conjugator.

  4. Compact large-aperture Fabry-Perot interferometer modules for gas spectroscopy at mid-IR

    NASA Astrophysics Data System (ADS)

    Kantojärvi, Uula; Varpula, Aapo; Antila, Tapani; Holmlund, Christer; Mäkynen, Jussi; Näsilä, Antti; Mannila, Rami; Rissanen, Anna; Antila, Jarkko; Disch, Rolf J.; Waldmann, Torsten A.

    2014-03-01

    VTT has developed Fabry-Pérot Interferometers (FPI) for visible and infrared wavelengths since 90's. Here we present two new platforms for mid-infrared gas spectroscopy having a large optical aperture to provide high optical throughput but still enabling miniaturized instrument size. First platform is a tunable filter that replaces a traditional filter wheel, which operates between wavelengths of 4-5 um. Second platform is for correlation spectroscopy where the interferometer provides a comb-like transmission pattern mimicking absorption of diatomic molecules at the wavelength range of 4.7-4.8 um. The Bragg mirrors have 2-4 thin layers of polysilicon and silicon oxide.

  5. Design of large aperture, low mass vacuum windows

    SciTech Connect

    Leonhardt, W.J.; Mapes, M.

    1993-07-01

    Large vacuum vessels are employed downstream of fixed targets in High Energy Physics experiments to provide a long path for particles to traverse without interacting with air molecules. These vessels generally have a large aperture opening known as a vacuum window which employs a thin membrane to preserve the vacuum environment yet allows the particles to pass through with a minimal effect on them. Several large windows have been built using a composite of Kevlar/Mylar including circular windows to a diameter of 96.5 cm and rectangular windows up to 193 cm x 86 cm. This paper describes the design, fabrication, testing and operating experience with these windows and relates the actual performance to theoretical predictions.

  6. Design of large aperture, low mass vacuum windows

    SciTech Connect

    Leonhardt, W.J.; Mapes, M.

    1993-01-01

    Large vacuum vessels are employed downstream of fixed targets in High Energy Physics experiments to provide a long path for particles to traverse without interacting with air molecules. These vessels generally have a large aperture opening known as a vacuum window which employs a thin membrane to preserve the vacuum environment yet allows the particles to pass through with a minimal effect on them. Several large windows have been built using a composite of Kevlar/Mylar including circular windows to a diameter of 96.5 cm and rectangular windows up to 193 cm x 86 cm. This paper describes the design, fabrication, testing and operating experience with these windows and relates the actual performance to theoretical predictions.

  7. Optical imaging process based on two-dimensional Fourier transform for synthetic aperture imaging ladar

    NASA Astrophysics Data System (ADS)

    Sun, Zhiwei; Zhi, Ya'nan; Liu, Liren; Sun, Jianfeng; Zhou, Yu; Hou, Peipei

    2013-09-01

    The synthetic aperture imaging ladar (SAIL) systems typically generate large amounts of data difficult to compress with digital method. This paper presents an optical SAIL processor based on compensation of quadratic phase of echo in azimuth direction and two dimensional Fourier transform. The optical processor mainly consists of one phase-only liquid crystal spatial modulator(LCSLM) to load the phase data of target echo and one cylindrical lens to compensate the quadratic phase and one spherical lens to fulfill the task of two dimensional Fourier transform. We show the imaging processing result of practical target echo obtained by a synthetic aperture imaging ladar demonstrator. The optical processor is compact and lightweight and could provide inherent parallel and the speed-of-light computing capability, it has a promising application future especially in onboard and satellite borne SAIL systems.

  8. Fabrication and test of a concave oblate ellipsoid with large relative aperture

    NASA Astrophysics Data System (ADS)

    Li, Ke-xin; Yuan, Li-yin; Hao, Pei-ming

    2010-10-01

    Fabrication and test of the concave oblate ellipsoid becomes more difficult as the mirror relative aperture gets larger. The concave oblate ellipsoid discussed in this paper, has a very large relative aperture. Two processing methods are introduced. One is drilling sub-mirror from the mother mirror, the other is processing sub-mirror merely. A novel method to calculate aspheric grinding amount of the latter method is proposed. As the clear aperture and aperture decenter of the concave oblate ellipsoid in this paper are not large, the former processing method is finally adopted. Two online processing testing methods are proposed. One is reflective auto-collimating test; the other is refractive auto-collimating test. As for the former, a negative power lens is applied to compensate the positive spherical aberration of the concave oblate ellipsoid. The compensator has a negative - negative - positive configuration. As for the latter, the back surface of the spherical is designed to be an auxiliary spherical one. Its compensator is negative- positive- positive compensator. Besides, a high-precision plane is used to realize auto-collimating test. And the form test is selected for its online processing testing. By optical design of the compensator and gradual aberration optimization of its alignment, the test accuracy of the oblate ellipsoid shape can be achieved 1/10λ (632.8nm).

  9. Fabrication of large aperture SiC brazing mirror

    NASA Astrophysics Data System (ADS)

    Li, Ang; Wang, Peipei; Dong, Huiwen; Wang, Peng

    2016-10-01

    The SiC brazing mirror is the mirror whose blank is made by assembling together smaller SiC pieces with brazing technique. Using such kinds of joining techniques, people can manufacture large and complex SiC assemblies. The key technologies of fabricating and testing SiC brazing flat mirror especially for large aperture were studied. The SiC brazing flat mirror was ground by smart ultrasonic-milling machine, and then it was lapped by the lapping smart robot and measured by Coordinate Measuring Machine (CMM). After the PV of the surface below 4um, we did classic coarse polishing to the surface and studied the shape of the polishing tool which directly effects removal amount distribution. Finally, it was figured by the polishing smart robot and measured by Fizeau interferometer. We also studied the influence of machining path and removal functions of smart robots on the manufacturing results and discussed the use of abrasive in this process. At last, an example for fabricating and measuring a similar SiC brazing flat mirror with the aperture of 600 mm made by Shanghai Institute of Ceramics was given. The mirror blank consists of 6 SiC sectors and the surface was finally processed to a result of the Peak-to-Valley (PV) 150nm and Root Mean Square (RMS) 12nm.

  10. Optomechanical analysis of the flexure mounting configuration of large-aperture laser transport mirror

    NASA Astrophysics Data System (ADS)

    Zhang, Zheng; Quan, Xusong; Wang, Hui; Liu, Tianye; Xiong, Zhao; Yuan, Xiaodong; Rong, Yiming

    2017-02-01

    Motivated by the demand to minimize the mount-induced wavefront aberration of the large-aperture laser transport mirror, a low-stress flexure mounting configuration is proposed. Specific optomechanical analyses, including theoretical modeling, numerical analysis and field experiment, are presented. The mechanical properties of the flexure support were studied specifically. Besides, the relation between the mounting forces and the root-mean-square of the gradients (GRMS) value of the mirror surface is studied. Then, the appropriate value of the bolt preload is set to 500N, with which the GRMS value is just 5.35 nm/cm. The results indicate that the flexure mounting configuration is indeed a feasible and promising method to solve the mount-induced distortion problem of large-aperture optics.

  11. Large-aperture chirped volume Bragg grating based fiber CPA system.

    PubMed

    Liao, Kai-Hsiu; Cheng, Ming-Yuan; Flecher, Emilie; Smirnov, Vadim I; Glebov, Leonid B; Galvanauskas, Almantas

    2007-04-16

    A fiber chirped pulse amplification system at 1558 nm was demonstrated using a large-aperture volume Bragg grating stretcher and compressor made of Photo-Thermal-Refractive (PTR) glass. Such PTR glass based gratings represent a new type of pulse stretching and compressing devices which are compact, monolithic and optically efficient. Furthermore, since PTR glass technology enables volume gratings with transverse apertures which are large, homogeneous and scalable, it also enables high pulse energies and powers far exceeding those achievable with other existing compact pulse-compression technologies. Additionally, reciprocity of chirped gratings with respect to stretching and compression also enables to address a long-standing problem in CPA system design of stretcher-compressor dispersion mismatch.

  12. Large-aperture chirped volume Bragg grating based fiber CPA system

    NASA Astrophysics Data System (ADS)

    Liao, Kai-Hsiu; Cheng, Ming-Yuan; Flecher, Emilie; Smirnov, Vadim I.; Glebov, Leonid B.; Galvanauskas, Almantas

    2007-04-01

    A fiber chirped pulse amplification system at 1558nm was demonstrated using a large-aperture volume Bragg grating stretcher and compressor made of Photo-Thermal-Refractive (PTR) glass. Such PTR glass based gratings represent a new type of pulse stretching and compressing devices which are compact, monolithic and optically efficient. Furthermore, since PTR glass technology enables volume gratings with transverse apertures which are large, homogeneous and scalable, it also enables high pulse energies and powers far exceeding those achievable with other existing compact pulse-compression technologies. Additionally, reciprocity of chirped gratings with respect to stretching and compression also enables to address a long-standing problem in CPA system design of stretcher-compressor dispersion mismatch.

  13. The Advanced Technology Large Aperture Space Telescope (ATLAST): Science Drivers and Technology Developments

    NASA Technical Reports Server (NTRS)

    Postman, Marc; Brown, Tom; Sembach, Kenneth; Giavalisco, Mauro; Traub, Wesley; Stapelfeldt, Karl; Calzetti, Daniela; Oegerle, William; Rich, R. Michael; Stahl, H. Phillip; hide

    2011-01-01

    The Advanced Technology Large-Aperture Space Telescope (ATLAST) is a concept for an 8-meter to 16-meter UVOIR space observatory for launch in the 2025-2030 era. ATLAST will allow astronomers to answer fundamental questions at the forefront of modern astrophysics, including "Is there life elsewhere in the Galaxy?" We present a range of science drivers and the resulting performance requirements for ATLAST (8 to 16 milliarcsecond angular resolution, diffraction limited imaging at 0.5 m wavelength, minimum collecting area of 45 square meters, high sensitivity to light wavelengths from 0.1 m to 2.4 m, high stability in wavefront sensing and control). We also discuss the priorities for technology development needed to enable the construction of ATLAST for a cost that is comparable to current generation observatory-class space missions. Keywords: Advanced Technology Large-Aperture Space Telescope (ATLAST); ultraviolet/optical space telescopes; astrophysics; astrobiology; technology development.

  14. Optical Aperture Synthesis Object's Information Extracting Based on Wavelet Denoising

    NASA Astrophysics Data System (ADS)

    Fan, W. J.; Lu, Y.

    2006-10-01

    Wavelet denoising is studied to improve OAS(optical aperture synthesis) object's Fourier information extracting. Translation invariance wavelet denoising based on Donoho wavelet soft threshold denoising is researched to remove Pseudo-Gibbs in wavelet soft threshold image. OAS object's information extracting based on translation invariance wavelet denoising is studied. The study shows that wavelet threshold denoising can improve the precision and the repetition of object's information extracting from interferogram, and the translation invariance wavelet denoising information extracting is better than soft threshold wavelet denoising information extracting.

  15. Large-Aperture Membrane Active Phased-Array Antennas

    NASA Technical Reports Server (NTRS)

    Karasik, Boris; McGrath, William; Leduc, Henry

    2009-01-01

    Large-aperture phased-array microwave antennas supported by membranes are being developed for use in spaceborne interferometric synthetic aperture radar systems. There may also be terrestrial uses for such antennas supported on stationary membranes, large balloons, and blimps. These antennas are expected to have areal mass densities of about 2 kg/sq m, satisfying a need for lightweight alternatives to conventional rigid phased-array antennas, which have typical areal mass densities between 8 and 15 kg/sq m. The differences in areal mass densities translate to substantial differences in total mass in contemplated applications involving aperture areas as large as 400 sq m. A membrane phased-array antenna includes patch antenna elements in a repeating pattern. All previously reported membrane antennas were passive antennas; this is the first active membrane antenna that includes transmitting/receiving (T/R) electronic circuits as integral parts. Other integral parts of the antenna include a network of radio-frequency (RF) feed lines (more specifically, a corporate feed network) and of bias and control lines, all in the form of flexible copper strip conductors on flexible polymeric membranes. Each unit cell of a prototype antenna (see Figure 1) contains a patch antenna element and a compact T/R module that is compatible with flexible membrane circuitry. There are two membrane layers separated by a 12.7-mm air gap. Each membrane layer is made from a commercially available flexible circuit material that, as supplied, comprises a 127-micron-thick polyimide dielectric layer clad on both sides with 17.5-micron-thick copper layers. The copper layers are patterned into RF, bias, and control conductors. The T/R module is located on the back side of the ground plane and is RF-coupled to the patch element via a slot. The T/R module is a hybrid multilayer module assembled and packaged independently and attached to the membrane array. At the time of reporting the information for

  16. Factors affecting the performance of large-aperture microphone arrays

    NASA Astrophysics Data System (ADS)

    Silverman, Harvey F.; Patterson, William R.; Sachar, Joshua

    2002-05-01

    Large arrays of microphones have been proposed and studied as a possible means of acquiring data in offices, conference rooms, and auditoria without requiring close-talking microphones. When such an array essentially surrounds all possible sources, it is said to have a large aperture. Large-aperture arrays have attractive properties of spatial resolution and signal-to-noise enhancement. This paper presents a careful comparison of theoretical and measured performance for an array of 256 microphones using simple delay-and-sum beamforming. This is the largest currently functional, all digital-signal-processing array that we know of. The array is wall-mounted in the moderately adverse environment of a general-purpose laboratory (8 m×8 m×3 m). The room has a T60 reverberation time of 550 ms. Reverberation effects in this room severely impact the array's performance. However, the width of the main lobe remains comparable to that of a simplified prediction. Broadband spatial resolution shows a single central peak with 10 dB gain about 0.4 m in diameter at the -3 dB level. Away from that peak, the response is approximately flat over most of the room. Optimal weighting for signal-to-noise enhancement degrades the spatial resolution minimally. Experimentally, we verify that signal-to-noise gain is less than proportional to the square root of the number of microphones probably due to the partial correlation of the noise between channels, to variation of signal intensity with polar angle about the source, and to imperfect correlation of the signal over the array caused by reverberations. We show measurements of the relative importance of each effect in our environment.

  17. Factors affecting the performance of large-aperture microphone arrays.

    PubMed

    Silverman, Harvey F; Patterson, William R; Sachar, Joshua

    2002-05-01

    Large arrays of microphones have been proposed and studied as a possible means of acquiring data in offices, conference rooms, and auditoria without requiring close-talking microphones. When such an array essentially surrounds all possible sources, it is said to have a large aperture. Large-aperture arrays have attractive properties of spatial resolution and signal-to-noise enhancement. This paper presents a careful comparison of theoretical and measured performance for an array of 256 microphones using simple delay-and-sum beamforming. This is the largest currently functional, all digital-signal-processing array that we know of. The array is wall-mounted in the moderately adverse environment of a general-purpose laboratory (8 m x 8 m x 3 m). The room has a T60 reverberation time of 550 ms. Reverberation effects in this room severely impact the array's performance. However, the width of the main lobe remains comparable to that of a simplified prediction. Broadband spatial resolution shows a single central peak with 10 dB gain about 0.4 m in diameter at the -3 dB level. Away from that peak, the response is approximately flat over most of the room. Optimal weighting for signal-to-noise enhancement degrades the spatial resolution minimally. Experimentally, we verify that signal-to-noise gain is less than proportional to the square root of the number of microphones probably due to the partial correlation of the noise between channels, to variation of signal intensity with polar angle about the source, and to imperfect correlation of the signal over the array caused by reverberations. We show measurements of the relative importance of each effect in our environment.

  18. Partial feedback unstable resonator on small scale supersonic large aperture chemical laser

    NASA Astrophysics Data System (ADS)

    Wang, Hongyan; Wang, Rui; Li, Lei

    2015-05-01

    There is always a challenge on large aperture medium power laser's resonator design, stable resonator would supports significant higher order transverse modes, folded and telescope stable resonator are too complex and not preferred by engineers, unstable resonator need rather large round trip gain to compensate its high geometric out-coupling, which is difficult for this kind of laser since its gain length is limited due to the power level and large aperture. Partial feedback unstable resonator had been proposed to tackle this difficulty since the early days of laser development, however, the debates of its effect never stopped even with those distinguished optical resonator scientists such as Siegman, Anan'ev, and Weber. Recently integrated partial feedback unstable resonator design had been successfully demonstrated on a medium size chemical oxygen iodine laser. In this paper, we carry this resonator configuration on a small scale discharge driven supersonic nozzle array Hydrogen Fluoride chemical laser, a typical large aperture short gain length device. With magnification equals 4/3, we successfully get ten Watts level ring beam output.

  19. Sensitivity of synthetic aperture laser optical feedback imaging.

    PubMed

    Glastre, Wilfried; Lacot, Eric; Jacquin, Olivier; Hugon, Olivier; de Chatellus, Hugues Guillet

    2012-04-01

    In this paper, we compare the sensitivity of two imaging configurations, both based on laser optical feedback imaging (LOFI). The first one is direct imaging, which uses conventional optical focalization on target, and the second one is made by a synthetic aperture (SA) laser, which uses numerical focalization. We show that SA configuration allows us to obtain good resolutions with high working distance and that the drawback of SA imagery is that it has a worse photometric balance in comparison to a conventional microscope. This drawback is partially compensated by the important sensitivity of LOFI. Another interest of SA relies on the capacity of getting three-dimensional information in a single x-y scan.

  20. Experimental instrumentation system for the Phased Array Mirror Extendible Large Aperture (PAMELA) test program

    NASA Technical Reports Server (NTRS)

    Boykin, William H., Jr.

    1993-01-01

    Adaptive optics are used in telescopes for both viewing objects with minimum distortion and for transmitting laser beams with minimum beam divergence and dance. In order to test concepts on a smaller scale, NASA MSFC is in the process of setting up an adaptive optics test facility with precision (fraction of wavelengths) measurement equipment. The initial system under test is the adaptive optical telescope called PAMELA (Phased Array Mirror Extendible Large Aperture). Goals of this test are: assessment of test hardware specifications for PAMELA application and the determination of the sensitivities of instruments for measuring PAMELA (and other adaptive optical telescopes) imperfections; evaluation of the PAMELA system integration effort and test progress and recommended actions to enhance these activities; and development of concepts and prototypes of experimental apparatuses for PAMELA.

  1. Development of a large aperture Nb3Sn racetrack quadrupolemagnet

    SciTech Connect

    Ferracin, Paolo; Bartlett, Scott E.; Caspi, Shlomo; Dietderich,Daniel R.; Gourlay, Steven A.; Hannaford, Charles R.; Hafalia, AurelioR.; Lietzke, Alan F.; Mattafirri, Sara; McInturff, Alfred D.; Nyman,Mark; Sabbi, Gianluca

    2005-04-14

    The U.S. LHC Accelerator Research Program (LARP), a collaboration between BNL, FNAL, LBNL, and SLAC, has among its major objectives the development of advanced magnet technology for an LHC luminosity upgrade. The LBNL Superconducting Magnet Group supports this program with a broad effort involving design studies, Nb{sub 3}Sn conductor development, mechanical models, and basic prototypes. This paper describes the development of a large aperture Nb{sub 3}Sn racetrack quadrupole magnet using four racetrack coils from the LBNL Subscale Magnet (SM) Program. The magnet provides a gradient of 95 T/m in a 110 mm bore, with a peak field in the conductor of 11.2 T. The coils are prestressed by a mechanical structure based on a pre-tensioned aluminum shell, and axially supported with aluminum rods. The mechanical behavior has been monitored with strain gauges and the magnetic field has been measured. Results of the test are reported and analyzed.

  2. Time-gated ballistic imaging using a large aperture switching beam.

    PubMed

    Mathieu, Florian; Reddemann, Manuel A; Palmer, Johannes; Kneer, Reinhold

    2014-03-24

    Ballistic imaging commonly denotes the formation of line-of-sight shadowgraphs through turbid media by suppression of multiply scattered photons. The technique relies on a femtosecond laser acting as light source for the images and as switch for an optical Kerr gate that separates ballistic photons from multiply scattered ones. The achievable image resolution is one major limitation for the investigation of small objects. In this study, practical influences on the optical Kerr gate and image quality are discussed theoretically and experimentally applying a switching beam with large aperture (D = 19 mm). It is shown how switching pulse energy and synchronization of switching and imaging pulse in the Kerr cell influence the gate's transmission. Image quality of ballistic imaging and standard shadowgraphy is evaluated and compared, showing that the present ballistic imaging setup is advantageous for optical densities in the range of 8 < OD < 13. Owing to the spatial transmission characteristics of the optical Kerr gate, a rectangular aperture stop is formed, which leads to different resolution limits for vertical and horizontal structures in the object. Furthermore, it is reported how to convert the ballistic imaging setup into a schlieren-type system with an optical schlieren edge.

  3. ATLAST-9.2m: a Large-Aperture Deployable Space Telescope

    NASA Technical Reports Server (NTRS)

    Oergerle, William; Feinberg, Lee D.; Purves, Lloyd R.; Hyde, T. Tupper; Thronson, Harley A.; Townsend, Jacqueline A.; Postman, Marc; Bolear, Matthew R.; Budinoff, Jason G.; Dean, Bruce H.; Clampin, Mark C.; Ebbets, Dennis C.; Gong, Qian; Gull, Theodore R.; Howard, Joseph M.; Jones, Andrew L.; Lyon, Richard G.; Pasquale, Bert A.; Perrygo, Charles; Smith, Jeffrey S.; Thompson, Patrick L.; Woodgate, Bruce E.

    2010-01-01

    We present results of a study of a deployable version of the Advanced Technology Large-Aperture Space Telescope (ATLAST), designed to operate in a Sun-Earth L2 orbit. The primary mirror of the segmented 9.2-meter aperture has 36 hexagonal 1.315 m (flat to flat) glass mirrors. The architecture and folding of the telescope is similar to JWST, allowing it to fit into the 6.5 m fairing of a modest upgrade to the Delta-IV Heavy version of the Evolved Expendable Launch Vehicle (EELV). We discuss the overall observatory design, optical design, instruments, stray light, wavefront sensing and control, pointing and thermal control, and in-space servicing options.

  4. BLAST: The Balloon-Borne Large Aperture Submillimeter Telescope

    NASA Technical Reports Server (NTRS)

    Devlin, Mark; Ade, Peter; Bock, Jamie; Dicker, Simon; Griffin, Matt; Gunderson, Josh; Halpern, Mark; Hargrave, Peter; Hughes, David; Klein, Jeff

    2004-01-01

    BLAST is the Balloon-borne Large-Aperture Sub-millimeter Telescope. It will fly from a Long Duration Balloon (LDB) platform from Antarctica. The telescope design incorporates a 2 m primary mirror with large-format bolometer arrays operating at 250, 350 and 500 microns. By providing the first sensitive large-area (10 sq. deg.) sub-mm surveys at these wavelengths, BLAST will address some of the most important galactic and cosmological questions regarding the formation and evolution of stars, galaxies and clusters. Galactic and extragalactic BLAST surveys will: (1) identify large numbers of high-redshift galaxies; (2) measure photometric redshifts, rest-frame FIR luminosities and star formation rates thereby constraining the evolutionary history of the galaxies that produce the FIR and sub-mm background; (3) measure cold pre-stellar sources associated with the earliest stages of star and planet formation; (4) make high-resolution maps of diffuse galactic emission over a wide range of galactic latitudes. In addition to achieving the above scientific goals, the exciting legacy of the BLAST LDB experiment will be a catalogue of 3000-5000 extragalactic sub-mm sources and a 100 sq. deg. sub-mm galactic plane survey. Multi-frequency follow-up observations from SIRTF, ASTRO-F, and Herschel, together with spectroscopic observations and sub-arcsecond imaging from ALMA are essential to understand the physical nature of the BLAST sources.

  5. High-resolution fracture aperture mapping using optical profilometry

    NASA Astrophysics Data System (ADS)

    Ameli, Pasha; Elkhoury, Jean E.; Detwiler, Russell L.

    2013-10-01

    Fractures play an important role in the Earth's crust, often controlling both mechanical and transport processes. Developing a mechanistic understanding of these processes requires quantifying the roughness of fracture surfaces and the contacts and void spaces between fracture surfaces at high spatial resolution (10s of microns) over a broad range of scales (centimeters to meters). Here we present a scalable method for measuring fracture surfaces and reconstructing fracture aperture fields using an optical profilometer. We evaluate the method by measuring two fractured limestone cores; one is a tensile fracture with strong cross correlation between the surfaces and the other is a saw-cut, sand-blasted fracture with negligible cross correlation between the surfaces. Results of repeated measurements of these two fractures suggest that well-correlated surfaces, where the correlation between the surfaces can aid reconstruction, can be reproduced with local uncertainties with median standard deviation of 8 μm . Poorly correlated surfaces, where reconstruction relies solely upon the precision of the placement of the halves of the core on the profilometer stage, can be reproduced with local uncertainties with median standard deviation of 20 μm . Additionally, we quantified the accuracy of the technique by comparing calculated aperture profiles of a fractured concrete core to thin sections cut from the core after impregnating it with epoxy. The median deviation between the two measurements, which includes errors due to residual misalignment of the profiles, was 29 μm supporting the accuracy of the method. Our results emphasize the potential for using noncontact surface measurement techniques to accurately and precisely reconstruct fracture apertures over a wide range of length scales.

  6. Application of Large Aperture Emats to Weld Inspection

    NASA Astrophysics Data System (ADS)

    Maclauchlan, D. T.; Clark, S. P.; Hancock, J. W.

    2008-02-01

    One of the most significant developments in EMAT operation is the incorporation of phased array techniques. Phased array EMATs enable electronic beam steering and focusing while operating with temporally short pulses for good range resolution. Using phased array EMAT operation, multiple high powered pulsers are combined in the generation of the ultrasonic wave and multiple elements are combined in the reception of the ultrasonic wave, for improved sensitivity. EMATs make it practical to operate with shear horizontal (SH) waves and scan over a metal part's surface. An EMAT generated line force at the surface launches shear horizontal waves with uniform amplitude for beam angles from -90° to 90°. Shear horizontal waves also reflect without mode conversion from surfaces that are parallel to the polarization of the shear wave displacements. The combination of these advantages makes phased array EMATs well suited for weld inspection. Recently, BWXT Services has developed a 32 active channel EMAT phased array system for operation up to 5 MHz. In addition, each element can be constructed with several sub-elements, alternating in polarity, to effectively multiply the number of active elements for a restricted range of beam angles. For example by using elements comprised of 4 sub elements, a 128 active element aperture designed for operation with a nominal 60° beam angle provides good beam steering and focusing performance for 45° to 70° beam angles. The large active apertures allow the use of highly focused beams for good defect detection and high resolution imaging of weld defects. Application of this system to weld inspections has verified that good defect detection and imaging is possible. In addition, operation with SH waves has proven to provide improved detection of lack of fusion at the cap and root of the weld for certain weld geometries. The system has also been used to demonstrate the inspection of submerged metal arc welds while welding.

  7. APPLICATION OF LARGE APERTURE EMATS TO WELD INSPECTION

    SciTech Connect

    Maclauchlan, D. T.; Clark, S. P.; Hancock, J. W.

    2008-02-28

    One of the most significant developments in EMAT operation is the incorporation of phased array techniques. Phased array EMATs enable electronic beam steering and focusing while operating with temporally short pulses for good range resolution. Using phased array EMAT operation, multiple high powered pulsers are combined in the generation of the ultrasonic wave and multiple elements are combined in the reception of the ultrasonic wave, for improved sensitivity. EMATs make it practical to operate with shear horizontal (SH) waves and scan over a metal part's surface. An EMAT generated line force at the surface launches shear horizontal waves with uniform amplitude for beam angles from -90 deg. to 90 deg. Shear horizontal waves also reflect without mode conversion from surfaces that are parallel to the polarization of the shear wave displacements. The combination of these advantages makes phased array EMATs well suited for weld inspection. Recently, BWXT Services has developed a 32 active channel EMAT phased array system for operation up to 5 MHz. In addition, each element can be constructed with several sub-elements, alternating in polarity, to effectively multiply the number of active elements for a restricted range of beam angles. For example by using elements comprised of 4 sub elements, a 128 active element aperture designed for operation with a nominal 60 deg. beam angle provides good beam steering and focusing performance for 45 deg. to 70 deg. beam angles. The large active apertures allow the use of highly focused beams for good defect detection and high resolution imaging of weld defects. Application of this system to weld inspections has verified that good defect detection and imaging is possible. In addition, operation with SH waves has proven to provide improved detection of lack of fusion at the cap and root of the weld for certain weld geometries. The system has also been used to demonstrate the inspection of submerged metal arc welds while welding.

  8. Extremely large telescope: a twenty-five meter aperture for the twenty-first century

    NASA Astrophysics Data System (ADS)

    Bash, Frank N.; Sebring, Thomas A.; Ray, Frank B.; Ramsey, Lawrence W.

    1997-03-01

    The 10-meter class Hobby-Eberly telescope (HET), now nearing completion, provides technology for optical Arecibo-type telescopes which can be extrapolated to even larger apertures. Utilizing a fixed elevation angle and a spherical segmented primary mirror provides cost effective and pragmatic solutions to mirror mounting and fabrication. Arecibo-type tracking implies a greatly reduced tracking mass and no change to the gravity vector for the primary mirror. Such a telescope can address 70 percent of the available sky and exhibit optical quality easily sufficient for effective spectroscopy and photometry. The extremely large telescope takes advantage of several key engineering approaches demonstrated by the HET project to achieve a cost comparable to similarly-sized radio rather than optical telescopes. These engineering approaches include: bolted pre-manufactured primary mirror truss, factory manufactured geodesic enclosure dome, air bearing rotation of primary mirror, tracker, and dome systems directly on concrete piers, and tracking via a hexapod system. Current estimates put the cost of the ELT at $200 million for a 25-meter aperture utilizing a 33-meter primary mirror array. Construction of the ELT would provide the astronomy community with an optical telescope nearly an order of magnitude larger than even the largest telescopes in operation or under construction today.

  9. Fabrication of bowtie aperture antennas for producing sub-20 nm optical spots.

    PubMed

    Chen, Yang; Chen, Jianfeng; Xu, Xianfan; Chu, Jiaru

    2015-04-06

    Bowtie aperture antennas are known to generate sub-diffraction limited optical spots in the visible and near-infrared frequencies, which can be applied to many areas. Regular bowtie apertures fabricated by FIB suffer from tapered sidewall and rounded corner, which degrade its optical enhancement and localization. In this work, a new fabrication method is demonstrated to manufacture bowtie aperture antennas which can produce optical spots with lateral size smaller than 20 nm. We also employ numerical simulations to compute the near-field distribution on the surface of the bowtie aperture with topography extracted from the fabrication antennas. The near-field distribution measured by s-NSOM agrees well with the simulation and confirms the improved near-field localization of our bowtie aperture. This new fabrication method can be applied to other types of ridged apertures, which promises wide applications of deep sub-diffraction limited optical spots in many areas.

  10. Development of large aperture projection scatterometry for catalyst loading evaluation in proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Stocker, Michael T.; Barnes, Bryan M.; Sohn, Martin; Stanfield, Eric; Silver, Richard M.

    2017-10-01

    Widespread commercialization of proton exchange membrane fuel cells remains curbed by various manufacturing and infrastructure challenges. One such technical barrier identified by the U. S. Department of Energy is the need for high-speed, in-line process control of platinum-based catalyst layers in the membrane electrode assembly of the fuel cell. Using multiple reflectivity-based optical methods, such as optical scatterometry and large aperture projection scatterometry, we demonstrate in-line-capable catalyst loading measurements of carbon-supported Pt nanoparticle and Pt-alloy nanostructured thin film catalyst coated membranes. Large aperture projection scatterometry is a new high-throughput approach developed at the National Institute of Standards and Technology specifically for fuel cell manufacturing metrology. Angle- and wavelength-resolved measurements of these fuel cell soft goods validate the ability of reflectivity-based measurements to produce industrially relevant sensitivities to changes in Pt and Pt-alloy loading. The successful application of these optical methods to fuel cell manufacturing metrology directly addresses the shortage of high-throughput process control approaches needed to facilitate performance improvements and manufacturing cost-reductions required to make fuel cells commercially viable.

  11. Recent Enhancements of the Phased Array Mirror Extendible Large Aperture (PAMELA) Telescope Testbed at MSFC

    NASA Technical Reports Server (NTRS)

    Rakoczy, John; Montgomery, Edward E.; Lindner, Jeff

    2000-01-01

    Recent incremental upgrades to the Phased Array Mirror Extendible Large Aperture (PAMELA) telescope testbed have enabled the demonstration of phasing (with a monochromatic source) of clusters of primary mirror segments down to the diffraction limit. PAMELA upgrades include an improved Shack-Hartmann wavefront sensor, passive viscoelastic damping treatments for the voice-coil actuators, mechanical improvement of mirror surface figures, and optical bench baffling. This report summarizes the recent PAMELA upgrades, discusses the lessons learned, and presents a status of this unique testbed for wavefront sensing and control. The Marshall Space Flight Center acquired the Phased Array Mirror Extendible Large Aperture (PAMELA) telescope in 1993 after Kaman Aerospace was unable to complete integration and testing under the limited SDIO and DARPA funding. The PAMELA is a 36-segment, half-meter aperture, adaptive telescope which utilizes a Shack-Hartmann wavefront sensor, inductive coil edge sensors, voice coil actuators, imaging CCD cameras and interferometry for figure alignment, wavefront sensing and control. MSFC originally obtained the PAMELA to supplement its research in the interactions of control systems with flexible structures. In August 1994, complete tip, tilt and piston control was successfully demonstrated using the Shack-Hartmann wavefront sensor and the inductive edge sensors.

  12. Recent Enhancements of the Phased Array Mirror Extendible Large Aperture (PAMELA) Telescope Testbed at MSFC

    NASA Technical Reports Server (NTRS)

    Rakoczy, John; Burdine, Robert (Technical Monitor)

    2001-01-01

    Recent incremental upgrades to the Phased Array Mirror Extendible Large Aperture (PAMELA) telescope testbed have enabled the demonstration of phasing (with a monochromatic source) of clusters of primary mirror segments down to the diffraction limit. PAMELA upgrades include in improved Shack-Hartmann wavefront sensor, passive viscoelastic damping treatments for the voice-coil actuators, mechanical improvement of mirror surface figures, and optical bench baffling. This report summarizes the recent PAMELA upgrades, discusses the lessons learned, and presents a status of this unique testbed for wavefront sensing and control. The Marshall Space Flight Center acquired the Phased Array Mirror Extendible Large Aperture (PAMELA) telescope in 1993 after Kaman Aerospace was unable to complete integration and testing under the limited SDIO and DARPA funding. The PAMELA is a 36-segment, half-meter aperture, adaptive telescope which utilizes a Shack-Hartmann wavefront sensor, inductive coil edge sensors, voice coil actuators, imaging CCD cameras and interferometry for figure alignment, wavefront sensing and control. MSFC originally obtained the PAMELA to supplement its research in the interactions of control systems with flexible structures. In August 1994, complete tip, tilt and piston control was successfully demonstrated using the Shack-Hartmann wavefront sensor and the inductive edge sensors.

  13. High throughput optical lithography by scanning a massive array of bowtie aperture antennas at near-field

    PubMed Central

    Wen, X.; Datta, A.; Traverso, L. M.; Pan, L.; Xu, X.; Moon, E. E.

    2015-01-01

    Optical lithography, the enabling process for defining features, has been widely used in semiconductor industry and many other nanotechnology applications. Advances of nanotechnology require developments of high-throughput optical lithography capabilities to overcome the optical diffraction limit and meet the ever-decreasing device dimensions. We report our recent experimental advancements to scale up diffraction unlimited optical lithography in a massive scale using the near field nanolithography capabilities of bowtie apertures. A record number of near-field optical elements, an array of 1,024 bowtie antenna apertures, are simultaneously employed to generate a large number of patterns by carefully controlling their working distances over the entire array using an optical gap metrology system. Our experimental results reiterated the ability of using massively-parallel near-field devices to achieve high-throughput optical nanolithography, which can be promising for many important nanotechnology applications such as computation, data storage, communication, and energy. PMID:26525906

  14. High throughput optical lithography by scanning a massive array of bowtie aperture antennas at near-field.

    PubMed

    Wen, X; Datta, A; Traverso, L M; Pan, L; Xu, X; Moon, E E

    2015-11-03

    Optical lithography, the enabling process for defining features, has been widely used in semiconductor industry and many other nanotechnology applications. Advances of nanotechnology require developments of high-throughput optical lithography capabilities to overcome the optical diffraction limit and meet the ever-decreasing device dimensions. We report our recent experimental advancements to scale up diffraction unlimited optical lithography in a massive scale using the near field nanolithography capabilities of bowtie apertures. A record number of near-field optical elements, an array of 1,024 bowtie antenna apertures, are simultaneously employed to generate a large number of patterns by carefully controlling their working distances over the entire array using an optical gap metrology system. Our experimental results reiterated the ability of using massively-parallel near-field devices to achieve high-throughput optical nanolithography, which can be promising for many important nanotechnology applications such as computation, data storage, communication, and energy.

  15. High throughput optical lithography by scanning a massive array of bowtie aperture antennas at near-field

    NASA Astrophysics Data System (ADS)

    Wen, X.; Datta, A.; Traverso, L. M.; Pan, L.; Xu, X.; Moon, E. E.

    2015-11-01

    Optical lithography, the enabling process for defining features, has been widely used in semiconductor industry and many other nanotechnology applications. Advances of nanotechnology require developments of high-throughput optical lithography capabilities to overcome the optical diffraction limit and meet the ever-decreasing device dimensions. We report our recent experimental advancements to scale up diffraction unlimited optical lithography in a massive scale using the near field nanolithography capabilities of bowtie apertures. A record number of near-field optical elements, an array of 1,024 bowtie antenna apertures, are simultaneously employed to generate a large number of patterns by carefully controlling their working distances over the entire array using an optical gap metrology system. Our experimental results reiterated the ability of using massively-parallel near-field devices to achieve high-throughput optical nanolithography, which can be promising for many important nanotechnology applications such as computation, data storage, communication, and energy.

  16. Limitations of synthetic aperture laser optical feedback imaging.

    PubMed

    Glastre, Wilfried; Jacquin, Olivier; Hugon, Olivier; Guillet de Chatellus, Hugues; Lacot, Eric

    2012-11-01

    In this paper we study the origin and the effect of amplitude and phase noise on laser optical feedback imaging associated with a synthetic aperture (SA) imaging system. Amplitude noise corresponds to photon noise and acts as an additive noise; it can be reduced by increasing the global measurement time. Phase noise can be divided in three families: random, sinusoidal, and drift phase noise; we show that it acts as a multiplicative noise. We explain how we can reduce phase noise by making oversampling or multiple measurements depending on its type. This work can easily be extended to all SA systems (radar, laser, or terahertz), especially when raw holograms are acquired point by point.

  17. Improvements in large window and optics production

    NASA Astrophysics Data System (ADS)

    Hallock, Bob; Messner, Bill; Hall, Chris; Supranowitz, Chris

    2007-04-01

    Fabrication of large optics has been a topic of discussion for decades. As early as the late 1980s, computer-controlled equipment has been used to semi-deterministically correct the figure error of large optics over a number of process iterations. Magnetorheological Finishing, MRF®, was developed and commercialized in the late 1990's to predictably and reliably allow the user to achieve deterministic results on a variety of optical glasses, ceramics and other common optical materials. Large and small optics such as primary mirrors, conformal optics and off-axis components are efficiently fabricated using this approach. More recently, specific processes, MR Fluids and equipment have been developed and implemented to enhance results when finishing large aperture sapphire windows. MRF, by virtue of its unique removal process, overcomes many of the drawbacks of a conventional polishing process. For example, lightweighted optics often exhibit a quilted pattern coincident with their pocket cell structure following conventional pad-based polishing. MRF does not induce mid-frequency errors and is capable of removing existing quilt patterns. Further, odd aperture shapes and part geometries which can represent significant challenges to conventional polish processing are simply and easily corrected with MRF tools. Similarly, aspheric optics which can often present multiple obstacles-particularly when lightweighted and off-axis-typically have a departure from best-fit sphere that is not well matched with to static pad-based polishing tools resulting in pad misfit and associated variations in removal. The conformal subaperture polishing tool inherent to the QED process works as well on typical circular apertures as it does on irregular shapes such as rectangles, petals and trapezoids for example and matches the surface perfectly at all points. Flats, spheres, aspheres and off-axis sections are easily corrected. The schedule uncertainties driven by edge roll and edge control

  18. Correction on the effect of numerical aperture in optical scatterometry

    NASA Astrophysics Data System (ADS)

    Li, Weiqi; Liu, Shiyuan; Zhang, Chuanwei; Chen, Xiuguo; Gu, Honggang

    2013-10-01

    Optical scatterometry, also referred to as optical critical dimension (OCD) metrology, has been introduced for critical dimension (CD) monitoring and overlay metrology with great success in recent years. Forward modeling to calculate the optical signature from the measured diffractive structure is one of the most important issues in OCD metrology. To simplify the forward modeling approach, such as rigorous coupled-wave analysis (RCWA), the incidence and azimuthal angles are usually assumed to be constant. However, since some focusing elements, such as focusing lens or parabolic mirrors with finite numerical aperture (NA), are always used to gain a sufficient small spot size onto the sample, this assumption is not true in the whole exit pupil of the focusing elements, leading to a modeling error in forward modeling, and finally leading to a fitting error in OCD metrology. In this paper, we propose a correction method with consideration of the effect of NA to decrease the modeling error in the forward modeling. The correction method is an average integral method based on Gaussian quadrature in two dimensions inside a circle, and is performed on forward modeling with varied incidence and azimuthal angles over the exit pupil. Experiments performed on silicon gratings with a Mueller matrix polarimeter have demonstrated that the proposed correction method achieves a higher accuracy in OCD metrology.

  19. Fibre Fabry - Perot cavity-based aperture probe for near-field optical microscopy systems

    SciTech Connect

    Kulchin, Yurii N; Vitrik, O B; Bezverbnyi, A V; Pustovalov, E V; Kuchmizhak, A A; Nepomnyashchii, A V

    2011-03-31

    We report a theoretical analysis and experimental study of the possibility of producing a novel type of interferometric near-field aperture probe for near-field optical microscopy systems using a fibre Fabry - Perot microcavity with a nanometre-scale aperture made in one of its output mirrors. The probe ensures a spatial resolution no worse than {lambda}/14. (fibre optics)

  20. Operation of the DREO (Defence Research Establishment Ottawa) Synthetic Aperture Radar Optical Correlator.

    DTIC Science & Technology

    1983-09-01

    Defence Research Establishment Ottawa and Canadian industry . This instrument was designed to correlate interferograms produced by synthetic aperture radar...incoherents. These de doctorat , Universit& Laval, 1975. 5. C.J. Brochu and N. Brousseau, Simulation of a Synthetic Aperture Radar Optical Correlator using a...optical correlator developed by the Defence Research Establishment Ottawa and Canadian industry . This instrument was designed to correlate

  1. Research on new-style flexure supports method for large-aperture transport mirror mounting

    NASA Astrophysics Data System (ADS)

    Quan, Xusong; Zhang, Zheng; Xiong, Zhao; Wang, Hui; Yuan, Xiaodong; Liu, Changchun

    2016-10-01

    In high-power solid-state laser facility (SG-III), focusing laser beams into the target center with precision better than 50 microns (RMS) is dependent on the stringent specifications of thousands of large-aperture transport mirror units and is a huge challenge on the surface aberration control of mirrors. The current mirror's mounting techniques with screw fastening loads has several engineering conundrums - low control precision for loads (higher scatter even +/-30%), and low assembly-rectification efficiency ( 100 screws). To improve the current screw-fastening method, a new-style flexure supports method, which has a wonderful performance on uniform control of the external loads and only uses 30 screws, is proposed to mount the mirror (size: 610mm×440mm×85mm). With theoretical modeling and FEM analysis, the impacts of mounting loads on mirror's surface aberrations are analyzed and discussed in detail, and the flexure supports system is designed. Finally, with experimental research and case studies, the proposed flexure supports method shows a powerful performance on even control precision of external loads with scatter even less than +/-10%, which is a promising mounting process to replace the threaded fasteners mounting the large-aperture optics. These improvements can lay a foundation for mounting process consistency, robustness, and assembly-rectification efficiency of large optical component.

  2. Large aperture fast neutron imaging detector with 10-ns time resolution

    NASA Astrophysics Data System (ADS)

    Arikawa, Y.; Matsubara, S.; Abe, Y.; Kato, Y.; Kishimoto, H.; Yogo, A.; Nishimura, H.; Nakai, M.; Shiraga, H.; Fujioka, S.; Azechi, H.; Otake, Y.; Mima, K.; Honda, Y.

    2017-02-01

    Fast neutrons, which are neutrons with energies greater than 1 MeV, are expected to be a source of nondestructive inspection for a large-size infrastructure such as a bridge girder because of their mean free path exceeding the meter. A neutron-imaging device with 10-ns time resolution can discriminate pulsed neutrons from X-rays via time of flight. For this purpose, we require a fast-response neutron imager with large aperture and high image resolution. A neutron-imaging device with time resolution of 10 ns and aperture size of 40 cm × 60 cm was developed. It was filled with fast response liquid scintillator [1] in an aluminum honeycomb plate, which converts neutrons to optical light images. The scintillation light images were relayed using an optical lens and detected using a fast response image intensified CCD. The detector was tested at an electron linear accelerator (LINAC) facility in Osaka University. A short X-ray pulse (30 ps pulse duration) was generated using LINAC, and X-ray radiograph images were obtained with a 10- ns exposure time duration. The radiograph images were well attenuated within 10-ns from the X-ray injection. A high energy X-ray image and a neutron radiograph image of a 30-cm thick concrete block with iron blocks located behind it were successfully observed. This promising technique could facilitate nondestructive inspection of large concrete constructions.

  3. BLAST: A balloon-borne, large-aperture, submillimetre telescope

    NASA Astrophysics Data System (ADS)

    Wiebe, Donald Victor

    BLAST is a balloon-borne large-aperture, submillimetre telescope, which makes large area (1--200 square degree) surveys of Galactic and extragalactic targets. Since BLAST observes in the stratosphere, it is able to make broad-band observations between 200 mum and 550 mum which are difficult or impossible to perform from the ground. BLAST has been designed to probe star formation both in the local Galaxy and in the high redshift (z = 1--4) universe. Because BLAST is flown on an unmanned stratospheric balloon platform, it has been designed to be able to operate autonomously, without needing operator intervention to perform its scientific goals. This thesis includes an overview of the design of the BLAST platform, with emphasis on the command and control systems used to operate the telescope. BLAST has been flown on two long-duration balloon flights. The first of these, from Esrange, Sweden in June of 2005, acquired ˜70 hours of primarily Galactic data. During the second flight, from Willy Field, Antarctica in December of 2006, BLAST acquired ˜225 hours of both Galactic and extragalactic data. Operational performance of the platform during these two flights is reviewed, with the goal of providing insight on how future flights can be improved. Reduction of the data acquired by these large-format bolometer arrays is a challenging procedure, and techniques developed for BLAST data reduction are reviewed. The ultimate goal of this reduction is the generation of high quality astronomical maps which can be used for subsequent portions of data analysis. This thesis treats, in detail, the iterative, maximum likelihood map maker developed for BLAST. Results of simulations performed on the map maker to characterise its ability to reconstruct astronomical signals are presented. Finally, astronomical maps produced by this map maker using real data acquired by BLAST are presented, with a discussion on non-physical map pathologies resulting from the data reduction pipeline and

  4. Low mass large aperture vacuum window development at CEBAF

    SciTech Connect

    Keppel, C.

    1995-04-01

    Large aperture low mass vacuum windows are being developed for the HMS (High Momentum Spectrometer) and SOS (Short Orbit Spectrometer) spectrometers in Hall C at CEBAF. Because multiple scattering degrades the performance of a spectrometer it is important that the volume be evacuated and that the entrance and exit windows be as low mass as possible. The material used for such windows must be thin and light enough so as to have minimum effect of the beam, and at the same time, be thick and strong enough to operate reliably and safely. To achieve these goals, composite vacuum windows have been constructed of a thin sheet of Mylar with a reinforcing fabric. Reinforcing fabrics such as Kevlar and Spectra are available with tensile strengths significantly greater than that of Mylar. A thin layer of Myler remains necessary since the fabrics cannot achieve any sort of vacuum seal. The design, fabrication, testing, and operating experience with such composite windows for the Hall C spectrometers will be discussed.

  5. Error analysis of large aperture static interference imaging spectrometer

    NASA Astrophysics Data System (ADS)

    Li, Fan; Zhang, Guo

    2015-12-01

    Large Aperture Static Interference Imaging Spectrometer is a new type of spectrometer with light structure, high spectral linearity, high luminous flux and wide spectral range, etc ,which overcomes the contradiction between high flux and high stability so that enables important values in science studies and applications. However, there're different error laws in imaging process of LASIS due to its different imaging style from traditional imaging spectrometers, correspondingly, its data processing is complicated. In order to improve accuracy of spectrum detection and serve for quantitative analysis and monitoring of topographical surface feature, the error law of LASIS imaging is supposed to be learned. In this paper, the LASIS errors are classified as interferogram error, radiometric correction error and spectral inversion error, and each type of error is analyzed and studied. Finally, a case study of Yaogan-14 is proposed, in which the interferogram error of LASIS by time and space combined modulation is mainly experimented and analyzed, as well as the errors from process of radiometric correction and spectral inversion.

  6. Ultrasonic material characterization using large-aperture PVDF receivers.

    PubMed

    Adamowski, J C; Buiochi, F; Higuti, R T

    2010-02-01

    This work describes the use of a large-aperture PVDF receiver in the measurement of liquid density and composite material elastic constants. The density measurement of several liquids is obtained with accuracy of 0.2% using a conventional NDE emitter transducer and a 70-mm-diameter, 52-microm P(VDF-TrFE) membrane with gold electrodes. The determination of the elastic constants is based on the phase velocity measurement. Diffraction can lead to errors around 1% in velocity measurement when using alternatively the conventional pair of ultrasonic transducers (1-MHz frequency and 19-mm-diameter) operating in through-transmission mode, separated by a distance of 100 mm. This effect is negligible when using a pair of 10-MHz, 19-mm-diameter transducers. Nevertheless, the dispersion at 10 MHz can result in errors of about 0.5%, when measuring the velocity in composite materials. The use of an 80-mm diameter, 52-microm-thick PVDF membrane receiver practically eliminates the diffraction effects in phase velocity measurement. The elastic constants of a carbon fiber reinforced polymer were determined and compared with the values obtained by a tensile test.

  7. Development and testing of an actively controlled large-aperture Cassegrain Telescope for spacecraft deployment

    NASA Astrophysics Data System (ADS)

    Boone, Bradley G.; Bruzzi, Jonathan R.; Kluga, Bernard E.; Rogala, Eric W.; Hale, R. D.; Chen, Peter C.

    2004-10-01

    The National Aeronautics and Space Administration (NASA) is planning future deep space missions requiring space-based imaging reconnaissance of planets and recovery of imagery from these missions via optical communications. Both applications have similar requirements that can be met by a common aperture. The Johns Hopkins University Applied Physics Laboratory in collaboration with commercial and academic partners is developing a new approach to deploying and controlling large aperture (meter-class) optical telescopes on spacecraft that can be rapidly launched and deployed. The deployment mechanism uses flexible longeron struts to deploy the secondary. The active control system uses a fiber-coupled laser array near the focal plane that reflects four collimated laser beams off of the periphery of the secondary to four equally-disposed quad cell sensors at the periphery of the primary to correct secondary-to-primary misalignments and enable motion compensation. We describe a compensation technique that uses tip/tilt and piston actuators for quasi-static bias correction and dynamic motion compensation. We also describe preliminary optical tests using a commercial Schmidt-Cassegrain telescope in lieu of an ultra-lightweight composite Cassegrain, which is under development by Composite Mirror Applications, Inc. Finite element and ray trace modeling results for a 40 cm composite telescope design will also be described.

  8. Multichannel Optical Aperture Synthesis Imaging of zeta1 URSAE Majoris with the Navy Prototype Optical Interferometer

    DTIC Science & Technology

    1997-09-01

    Optical Interferometer (NPOI) to obtain the first multichannel optical aperture synthesis images of a star . We observed the spectroscopic binary ~1...interferom- etry had the potential of measuring the exceedingly small angular diameters of stars (Michelson & Pease 1921). Mich- elson also realized that...could be used to image stellar surfaces. The use of interfer- ometry to measure orbits of binary stars also began early in this century (Anderson

  9. Large amplitude tip/tilt estimation by geometric diversity for multiple-aperture telescopes

    NASA Astrophysics Data System (ADS)

    Vievard, S.; Cassaing, F.; Mugnier, L. M.

    2017-08-01

    A novel method nicknamed ELASTIC is proposed for the alignment of multiple-aperture telescopes, in particular segmented telescopes. It only needs the acquisition of two diversity images of an unresolved source, and is based on the computation of a modified, frequency-shifted, cross-spectrum. It provides a polychromatic large range tip/tilt estimation with the existing hardware and an inexpensive noniterative unsupervised algorithm. Its performance is studied and optimized by means of simulations. They show that with 5000 photo-electrons/sub-aperture/frame and 1024x1024 pixel images, residues are within the capture range of interferometric phasing algorithms such as phase diversity. The closed-loop alignment of a 6 sub-aperture mirror provides an experimental demonstration of the effectiveness of the method. Author accepted version. Final version is Copyright 2017 Optical Society of America. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modifications of the content of this paper are prohibited.

  10. Optical antenna of telescope for synthetic aperture ladar

    NASA Astrophysics Data System (ADS)

    Liu, Liren

    2008-08-01

    For synthetic aperture ladar (SAL) imaging, there are difficulties in the space domain because the size of optical antenna of telescope is up to six orders of magnitude larger than the wavelength. In this paper, we suggest a defocused and spatial phase masked telescope for reception to compensate the diffraction aberration from the target to match the directivity of heterodyne detection, a defocused and phase masked transmission telescope to send out a wavefront with an additional and controllable spatial quadratic phase to the phase history, and a circulated duplex to compensate the aberration for reception and to produce spatial phase bias for transmission concurrently in the same telescope. On this basis, the point target radar equation in a full space and time treatment is achieved. Correspondingly, the complete collection equations of 2-D data acquired in the range and azimuth directions for 2-D SAL imaging of the strip-map mode and the spotlight mode are developed. Then the imaging azimuth and range resolutions are redefined in terms of the idea of optical imaging by a lens, and the requirement for azimuth sampling is given. The paper systemically presents the all details.

  11. Dynamic aperture computation for the as-built CERN Large Hadron Collider and impact of main dipoles sorting

    NASA Astrophysics Data System (ADS)

    Fartoukh, S.; Giovannozzi, M.

    2012-04-01

    During the design phase of the CERN Large Hadron Collider the dynamic aperture, i.e. the amplitude of the domain in phase space where the particle motion is stable, was used as one of the most important figures-of-merit to specify the field quality of the various types of superconducting magnets and to quantify the machine performance. The programme of magnetic measurements performed during the production and acceptance testing of the magnets generated a large amount of information, which was used to obtain a best estimate of the dynamic aperture of the actual machine. In this paper the results of massive numerical simulations based on the measured field quality of several optical configurations and beam energies, are presented and discussed. The effect of the sorting of the main dipoles on the final value of the dynamic aperture has also been studied and the results are reviewed in detail.

  12. Absolute flatness testing of large synchrotron optics

    NASA Astrophysics Data System (ADS)

    Lin, Weihao; He, Yumei; Song, Li; Luo, Hongxin; Wang, Jie

    2014-09-01

    Interferometry is one of the most efficient techniques in surface figure testing while the transmission surface usually limits the accuracy. Besides, standard figure interferometers often have a typical aperture of about 150 mm diameter which can not satisfy the need of large optics calibration. A novel method for characterizing the absolute surface figure of long grazing-incidence optics used in synchrotron radiation beamlines is presented. We demonstrate oblique incidence interferometry to overcome the aperture limitation. Furthermore, multiple rotating measurements are used to remove the transmission surface errors. The new solution is simple and easy without dismantling the transmission flat throughout the calibration procedure. The theoretical derivation, experiment results and uncertainty analysis are presented.

  13. Advances in deployable structures and surfaces for large apertures in space

    NASA Astrophysics Data System (ADS)

    Santiago-Prowald, J.; Baier, H.

    2013-12-01

    Large apertures in space have applications for telecommunications, Earth observation and scientific missions. This paper reviews advances in mechanical architectures and technologies for large deployable apertures for space antennas and telescopes. Two complementary approaches are described to address this challenge: the deployment of structures based on quasi-rigid members and highly flexible structures. Regarding the first approach, deployable articulated structures are classified in terms of their kinematics as 3D or planar linkages in multiple variants, resulting in different architectures of radial, peripheral or modular constructions. A dedicated discussion on the number of degrees of freedom and constraints addresses the deployment reliability and thermo-elastic stability of large elastic structures in the presence of thermal gradients. This aspect has been identified as a design driver for new developments of peripheral ring and modular structures. Meanwhile, other design drivers are maintained, such as the optimization of mass and stiffness, overall accuracy and stability, and pragmatic aspects including controlled industrial development and a commitment to operators' needs. Furthermore, reflecting surface technologies and concepts are addressed with a view to the future, presenting advances in technical solutions for increasing apertures and reducing areal mass densities to affordable levels for future missions. Highly flexible materials capable of producing ultra-stable shells are described with reference to the state of the art and new developments. These concepts may enable large deployable surfaces for antennas and telescopes, as well as innovative optical concepts such as photon sieves. Shape adjustment and shape control of these surfaces are described in terms of available technologies and future needs, particularly for the reconfiguration of telecommunications antennas. In summary, the two complementary approaches described and reviewed cover the

  14. Numerical aperture characteristics of angle-ended plastic optical fiber

    NASA Astrophysics Data System (ADS)

    Gao, Cheng; Farrell, Gerard

    2003-03-01

    With the increasing information rates demanded in consumer, automotive and aeronautical applications, a low cost and high performance physical transmission medium is required. Compared with Silica Optical Fiber, Plastic Optical Fiber (POF) offers an economic solution for a range of high-capacity, short-haul applications in industrial and military environments. Recently, a new type of POF, the perfluorinated graded-index plastic optical fiber (PF GI-POF), has been introduced that has low losses and high bandwidth at the communication wavelengths 850 nm and 1300nm. POF is normally terminated perpendicular to the fiber axis. We propose an angle-ended POF, which is terminated at non-perpendicular angles to the fiber axis. The aim of the research is to investigate the numerical aperture (NA) characteristics of angle-ended POF along the major axis of the elliptical endface. A theoretical model indicates that the NA of the angle-ended POF will increase nonlinearly with tilt-angle and the acceptance cone will be deflected with the angle of the deflection increasing nonlinearly with tilt-angle. We present results for the measured NA and the measured deflection angle using the far-field radiation method. Results are presented for 13 angle-ended SI-POF tilt-angles. We also present results for theoretical value of NA and deflection angle as a function of tilt-angle. The agreement between the measured and theoretical value is good up to tilt-angles of about 15 degrees, beyond which deviation occurs.

  15. Large-pitch steerable synthetic transmit aperture imaging (LPSSTA)

    NASA Astrophysics Data System (ADS)

    Li, Ying; Kolios, Michael C.; Xu, Yuan

    2016-04-01

    A linear ultrasound array system usually has a larger pitch and is less costly than a phased array system, but loses the ability to fully steer the ultrasound beam. In this paper, we propose a system whose hardware is similar to a large-pitch linear array system, but whose ability to steer the beam is similar to a phased array system. The motivation is to reduce the total number of measurement channels M (the product of the number of transmissions, nT, and the number of the receive channels in each transmission, nR), while maintaining reasonable image quality. We combined adjacent elements (with proper delays introduced) into groups that would be used in both the transmit and receive processes of synthetic transmit aperture imaging. After the M channels of RF data were acquired, a pseudo-inversion was applied to estimate the equivalent signal in traditional STA to reconstruct a STA image. Even with the similar M, different choices of nT and nR will produce different image quality. The images produced with M=N2/15 in the selected regions of interest (ROI) were demonstrated to be comparable with a full phased array, where N is the number of the array elements. The disadvantage of the proposed system is that its field of view in one delay-configuration is smaller than a standard full phased array. However, by adjusting the delay for each element within each group, the beam can be steered to cover the same field of view as the standard fully-filled phased array. The LPSSTA system might be useful for 3D ultrasound imaging.

  16. Large-aperture Dove prism for a rotational shearing interferometer

    NASA Astrophysics Data System (ADS)

    Moreno, Ivan; Paez, Gonzalo; Garcia-Marquez, Jorge; Strojnik, Marija

    2002-12-01

    An analytical expression is derived for the tilt introduced into a wave front by a Dove prism with manufacturing errors: error in the base angles and in the pyramidal angle. We found that the tilt decreases when the base angles are increased above the values of traditional design. The increase in the length-aperture ratio of a prism is detrimental to its performance. However, a Dove prism with a widened aperture increases throughput and keeps prism weight manageable for implementation in the rotational shearing interferometer. Thus, we propose a Dove prism designed with a widened aperture to increase throughput in the rotational shearing interferometer and with larger base angles to minimize the wave-front tilt introduced due to manufacturing errors.

  17. Optical Ground Terminals Using Multi Aperture Digital Coherent Combining

    DTIC Science & Technology

    2017-10-01

    from four parallel receiver chains. II. SYSTEM ARCHITECTURE Figure 1 shows an example multi-aperture receiver architec- ture that uses digital coherent...apertures by a distance much greater than r0, the received signals experience statistically independent fading processes. After summing the signals the...lossless combining of four apertures. These results show lossless combining down to the lowest tested power level of -15 dB PPB/receiver. An important next

  18. Grating-flanked plasmonic coaxial apertures for efficient fiber optical tweezers.

    PubMed

    Saleh, Amr A E; Sheikhoelislami, Sassan; Gastelum, Steven; Dionne, Jennifer A

    2016-09-05

    Subwavelength plasmonic apertures have been foundational for direct optical manipulation of nanoscale specimens including sub-100 nm polymeric beads, metallic nanoparticles and proteins. While most plasmonic traps result in two-dimensional localization, three-dimensional manipulation has been demonstrated by integrating a plasmonic aperture on an optical fiber tip. However, such 3D traps are usually inefficient since the optical mode of the fiber and the subwavelength aperture only weakly couple. In this paper we design more efficient optical-fiber-based plasmonic tweezers combining a coaxial plasmonic aperture with a plasmonic grating coupler at the fiber tip facet. Using full-field finite difference time domain analysis, we optimize the grating design for both gold and silver fiber-based coaxial tweezers such that the optical transmission through the apertures is maximized. With the optimized grating, we show that the maximum transmission efficiency increases from 2.5% to 19.6% and from 1.48% to 16.7% for the gold and silver structures respectively. To evaluate their performance as optical tweezers, we calculate the optical forces and the corresponding trapping potential on dielectric particles interacting with the apertures. We demonstrate that the enahncement in the transmission translates into an equivalent increase in the optical forces. Consequently, the optical power required to achieve stable optical trapping is significantly reduced allowing for efficient localization and 3D manipulation of sub-30 nm dielectric particles.

  19. Optical aperture area determination for accurate illuminance and luminous efficacy measurements of LED lamps

    NASA Astrophysics Data System (ADS)

    Dönsberg, Timo; Mäntynen, Henrik; Ikonen, Erkki

    2016-06-01

    The measurement uncertainty of illuminance and, consequently, luminous flux and luminous efficacy of LED lamps can be reduced with a recently introduced method based on the predictable quantum efficient detector (PQED). One of the most critical factors affecting the measurement uncertainty with the PQED method is the determination of the aperture area. This paper describes an upgrade to an optical method for direct determination of aperture area where superposition of equally spaced Gaussian laser beams is used to form a uniform irradiance distribution. In practice, this is accomplished by scanning the aperture in front of an intensity-stabilized laser beam. In the upgraded method, the aperture is attached to the PQED and the whole package is transversely scanned relative to the laser beam. This has the benefit of having identical geometry in the laser scanning of the aperture area and in the actual photometric measurement. Further, the aperture and detector assembly does not have to be dismantled for the aperture calibration. However, due to small acceptance angle of the PQED, differences between the diffraction effects of an overfilling plane wave and of a combination of Gaussian laser beams at the circular aperture need to be taken into account. A numerical calculation method for studying these effects is discussed in this paper. The calculation utilizes the Rayleigh-Sommerfeld diffraction integral, which is applied to the geometry of the PQED and the aperture. Calculation results for various aperture diameters and two different aperture-to-detector distances are presented.

  20. Large optics for the National Ignition Facility

    SciTech Connect

    Baisden, P.

    2015-01-12

    The National Ignition Facility (NIF) laser with its 192 independent laser beams is not only the world’s largest laser, it is also the largest optical system ever built. With its 192 independent laser beams, the NIF requires a total of 7648 large-aperture (meter-sized) optics. One of the many challenges in designing and building NIF has been to carry out the research and development on optical materials, optics design, and optics manufacturing and metrology technologies needed to achieve NIF’s high output energies and precision beam quality. This paper describes the multiyear, multi-supplier, development effort that was undertaken to develop the advanced optical materials, coatings, fabrication technologies, and associated process improvements necessary to manufacture the wide range of NIF optics. The optics include neodymium-doped phosphate glass laser amplifiers; fused silica lenses, windows, and phase plates; mirrors and polarizers with multi-layer, high-reflectivity dielectric coatings deposited on BK7 substrates; and potassium di-hydrogen phosphate crystal optics for fast optical switches, frequency conversion, and polarization rotation. Also included is a discussion of optical specifications and custom metrology and quality-assurance tools designed, built, and fielded at supplier sites to verify compliance with the stringent NIF specifications. In addition, a brief description of the ongoing program to improve the operational lifetime (i.e., damage resistance) of optics exposed to high fluence in the 351-nm (3ω) is provided.

  1. Design quadrilateral apertures in binary computer-generated holograms of large space bandwidth product.

    PubMed

    Wang, Jing; Sheng, Yunlong

    2016-09-20

    A new approach for designing the binary computer-generated hologram (CGH) of a very large number of pixels is proposed. Diffraction of the CGH apertures is computed by the analytical Abbe transform and by considering the aperture edges as the basic diffracting elements. The computation cost is independent of the CGH size. The arbitrary-shaped polygonal apertures in the CGH consist of quadrilateral apertures, which are designed by assigning the binary phases using the parallel genetic algorithm with a local search, followed by optimizing the locations of the co-vertices with a direct search. The design results in high performance with low image reconstruction error.

  2. Topology optimization-based lightweight primary mirror design of a large-aperture space telescope.

    PubMed

    Liu, Shutian; Hu, Rui; Li, Quhao; Zhou, Ping; Dong, Zhigang; Kang, Renke

    2014-12-10

    For the large-aperture space telescope, the lightweight primary mirror design with a high-quality optical surface is a critical and challenging issue. This work presents a topology optimization-based design procedure for a lightweight primary mirror and a new mirror configuration of a large-aperture space telescope is obtained through the presented design procedure. Inspired by the topology optimization method considering cast constraints, an optimization model for the configuration design of the mirror back is proposed, through which the distribution and the heights of the stiffeners on the mirror back can be optimized simultaneously. For the purpose of minimizing the optical surface deviation due to self-weight and polishing pressure loadings, the objective function is selected as to maximize the mirror structural stiffness, which can be achieved by minimizing the structural compliance. The total mass of the primary mirror is assigned as the constraint. In the application example, results of the optimized design topology for two kinds of mass constraints are presented. Executing the design procedure for specific requirements and postprocessing the topology obtained of the structure, a new mirror configuration with tree-like stiffeners and a multiple-arch back in double directions is proposed. A verification model is constructed to evaluate the design results and the finite element method is used to calculate the displacement of the mirror surface. Then the RMS deviation can be obtained after fitting the deformed surface by Zernike polynomials. The proposed mirror is compared with two classical mirrors in the optical performance, and the comparison results demonstrate the superiority of the new mirror configuration.

  3. Designs for a large-aperture telescope to map the CMB 10× faster.

    PubMed

    Niemack, Michael D

    2016-03-01

    Current large-aperture cosmic microwave background (CMB) telescopes have nearly maximized the number of detectors that can be illuminated while maintaining diffraction-limited image quality. The polarization-sensitive detector arrays being deployed in these telescopes in the next few years will have roughly 10⁴ detectors. Increasing the mapping speed of future instruments by at least an order of magnitude is important to enable precise probes of the inflationary paradigm in the first fraction of a second after the big bang and provide strong constraints on cosmological parameters. The CMB community has begun planning a next generation "Stage IV" CMB project that will be comprised of multiple telescopes with between 10⁵-10⁶ detectors to pursue these goals. This paper introduces the new crossed Dragone telescope and receiver optics designs that increase the usable diffraction-limited field-of-view, and therefore the mapping speed, by an order of magnitude compared to the upcoming generation of large-aperture instruments. Polarization systematics and engineering considerations are presented, including a preliminary receiver model to demonstrate that these designs will enable high efficiency illumination of >10⁵ detectors in a next generation CMB telescope.

  4. Study on supporting force sensing and control during large aperture space mirror test

    NASA Astrophysics Data System (ADS)

    Zhang, Long; Hu, Wenqi; Zheng, Liehua; Hao, Peiming

    2016-10-01

    During the machining of large aperture lightweight space mirror, the mirror figure consistency between ground test and space mission is a problem. In order to effectively control the supporting deformation effect on test results in gravity environment, in view of a 1.2-m space mirror with back blind holes, a supporting method for optical axis horizontal test is proposed, with this method, mirror under test is positioned by three center hole surfaces and supported by six external hole surfaces. The effect of deformation caused by different supporting force value, area and position is analyzed by finite element method, the simulation results show that this supporting method can control the mirror supporting deformation within PV0.035λ rms0.005λ. The actual supporting system uses soft expansion mandrel to control the mirror position and pneumatic lever to realize the floating support. In order to ensure that the support force can evenly distribute on the contact surface, a pressure mapping system is adopted to measure the interface pressure between the mirror blind holes and the soft supporting pads for the first time. This method can meet the test requirements of rms=1/40λ mirror and provides a technical support for high precision test of large aperture space mirror with back blind holes.

  5. Focussed ion beam machined cantilever aperture probes for near-field optical imaging.

    PubMed

    Jin, E X; Xu, X

    2008-03-01

    Near-field optical probe is the key element of a near-field scanning optical microscopy (NSOM) system. The key innovation in the first two NSOM experiments (Pohl et al., 1984; Lewis et al., 1984) is the fabrications of a sub-wavelength optical aperture at the apex of a sharply pointed transparent probe tip with a thin metal coating. This paper discusses the routine use of focussed ion beam (FIB) to micro-machine NSOM aperture probes from the commercial silicon nitride cantilevered atomic force microscopy probes. Two FIB micro-machining approaches are used to form a nanoaperture of controllable size and shape at the apex of the tip. The FIB side slicing produces a silicon nitride aperture on the flat-end tips with controllable sizes varying from 120 nm to 30 nm. The FIB head-on drilling creates holes on the aluminium-coated tips with sizes down to 50 nm. Nanoapertures in C and bow tie shapes can also be patterned using the FIB head-on milling method to possibly enhance the optical transmission. A transmission-collection NSOM system is constructed from a commercial atomic force microscopy to characterize the optical resolution of FIB-micro-machined aperture tips. The optical resolution of 78 nm is demonstrated by an aperture probe fabricated by FIB head-on drilling. Simultaneous topography imaging can also be realized using the same probe. By mapping the optical near-field from a bow-tie aperture, optical resolution as small as 59 nm is achieved by an aperture probe fabricated by the FIB side slicing method. Overall, high resolution and reliable optical imaging of routinely FIB-micro-machined aperture probes are demonstrated.

  6. Multichannel optical aperture synthesis imaging of zeta1 URSAE majoris with the Navy prototype optical interferometer.

    NASA Astrophysics Data System (ADS)

    Benson, J. A.; Hutter, D. J.; Elias, N. M., II; Bowers, P. F.; Johnston, K. J.; Hajian, A. R.; Armstrong, J. T.; Mozurkewich, D.; Pauls, T. A.; Rickard, L. J.; Hummel, C. A.; White, N. M.; Black, D.; Denison, C. S.

    1997-09-01

    We have used the Navy Prototype Optical Interferometer (NPOI) to obtain the first multi-channel optical aperture synthesis images of a star. We observed the spectroscopic binary zeta (1) Ursae Majoris at 6 to 10 milliarcseconds separation during seven nights, using three interferometric baselines and 19 spectral channels (lambda lambda520 - 850 nm) of the NPOI. After editing, a typical 90 sec scan yielded fringe visibilities at 50 spatial frequencies and closure phases at 15 wavelengths. Three to five scans were obtained each night. The separations and position angles are in good agreement with the visual orbit obtained with the Mark III interferometer (Hummel et al.markcite{hum1} 1995 [AJ, 110, 376]) but show small systematic difference that can be used to improve the orbit. The closure phase data provide a sensitive measure of the magnitude difference between the components. These results demonstrate the power of broad-band interferometric observations for fast imaging and the utility of vacuum delay lines for simultaneous observations over a wide band. These observations are the first to produce simultaneous visibilities and closure phases with a separate-aperture optical interferometer, and the second to produce closure phase images, following the results from COAST reported by Baldwin et al.markcite{bal} (1996 [A&A, 306, L13]). The angular resolution here is the highest ever achieved at visual wavelengths, exceeding by an order of magnitude the best thus far achieved by any single-aperture optical telescope. We generated complex visibilities and closure phases (the data types commonly used in radio interferometry) from the optical data and used standard radio interferometry techniques to produce these images. However, the fundamental observables of optical interferometry, the squared visibility amplitude and the closure phase, require the development of new analysis techniques.

  7. Optical configuration of an upconverted millimeter-wave distributed aperture imaging system

    NASA Astrophysics Data System (ADS)

    Dillon, Thomas E.; Schuetz, Christopher A.; Martin, Richard D.; Stein, E. Lee, Jr.; Samluk, Jesse P.; Mackrides, Daniel G.; Mirotznik, Mark S.; Prather, Dennis W.

    2009-09-01

    Millimeter-wave (mmW) imaging is presently a subject of considerable interest due to the ability of mmW radiation to penetrate obscurants while concurrently exhibiting low atmospheric absorption loss in particular segments of the spectrum, including near 35 and 94 GHz. As a result, mmW imaging affords an opportunity to see through certain levels of fog, rain, cloud cover, dust, and blowing sand, providing for situational awareness where visible and infrared detectors are unable to perform. On the other hand, due to the relatively long wavelength of the radiation, achieving sufficient resolution entails large aperture sizes, which furthermore leads to volumetric scaling of the imaging platform when using conventional refractive optics. Alternatively, distributed aperture imaging can achieve comparable resolution in an essentially two-dimensional form factor by use of a number of smaller subapertures through which the image is interferometrically synthesized. The novelty of our approach lies in the optical upconversion of the mmW radiation as sidebands on carrier laser beams using electro-optic modulators. These sidebands are subsequently stripped from the carrier using narrow passband optical filters and a spatial Fourier transform is performed by means of a simple lens to synthesize the image, which is then viewed using a standard near-infrared focal plane array (FPA). Consequently, the optical configuration of the back-end processor represents a major design concern for the imaging system. As such, in this paper we discuss the optical configuration along with some of the design challenges and present preliminary imaging data validating the system performance.

  8. A pump driving liquid cooling circuit method for the aperture of an infrared cold optical system

    NASA Astrophysics Data System (ADS)

    Xie, RongJian

    2017-06-01

    To enhance the optical recognition and wavelength filtering of an infrared cold optical system, some lens need to be maintained within a certain temperature range, which requires specific thermal management of the aperture. A 250K liquid cooling circuit designed for this purpose is introduced, and the experimental results established and operated in a vacuum environmental simulation chamber is carried out and analyzed. A practical cooling power source of radiation cooling equipment is adopted and the sun exposure heat load is imitated by array of planar membrane heaters attached on the specific designed structure of the aperture. Controlling the aperture temperature and improving the optical system performance are proved effective. Numerical optimization of the cooling circuit and simulation of the aperture are performed , and the factors affect the optical system performance in the mean time are also investigated.

  9. Large Optics Technology.

    DTIC Science & Technology

    1986-05-22

    EEEEEEEEEEmhEE SENSEffl -2-5 12" 110111111 LLLo 111M1. 2 15 .1 111-= NATIONAL BUREAU OF S Mouopy *9sO9u TESI , C N LARGE OPTICS TECHNOLOGY FINAL...Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 1981 !mw ’(’* 17 ABSTRACT The mirrors used in high energy laser systems...SCIENCES (GRADUATE) In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 1982

  10. Analysis of temporal contrast degradation due to wave front deviation in large aperture ultra-short pulse focusing system

    NASA Astrophysics Data System (ADS)

    Zhu, Ping; Xie, Xinglong; Zhu, Jianqiang; Zhu, Haidong; Yang, Qingwei; Kang, Jun; Guo, Ailin; Gao, Qi

    2014-11-01

    In extremely intense laser system used for plasma physics experiments, temporal contrast is an important property of the ultra-short pulse. In this paper, we theoretically study the temporal contrast degradation due to wave front deviation in large aperture ultra-short pulse focusing system. Two-step focusing fast Fourier transform (FFT) algorithm with the coordinate transform based on Fresnel approximation in space domain and Fourier integral transform method in time domain were used to simulate the focusing process spatially and temporally, in which the spatial distribution of ultra-short pulse temporal contrast characteristics at the focal spot is related to the wave front in large aperture off-axis parabolic mirror focusing optical system. Firstly, temporal contrast degradation due to wave front noise with higher spatial frequency is analyzed and appropriate evaluation parameter for large aperture ultra-short pulse focusing system is put forward from the perspective of temporal contrast. Secondly, the influence of wave front distortion with lower spatial frequency on temporal contrast is revealed comparing different degradation characteristics of various aberrations. At last, a method by controlling and optimizing the wave front to prevent temporal contrast degradation in large aperture ultra-short laser system is proposed, which is of great significance for high temporal contrast petawatt laser facilities.

  11. Wavelength dependence of the numerical aperture of optical fibers

    NASA Astrophysics Data System (ADS)

    Kersten, R. Th.; Le-Hiep, T.

    1982-03-01

    Wavelength resolved measurements of the numerical apertures and the profiles of graded index fibers have been performed by the far- and near-field methods, respectively. Quantitative results for the spectral dispersion of the numerical aperture of fibers are in very good agreement with theoretical results, which are obtained by using a 3-term Sellmeier series. Together with spectral attenuation measurements these results allow the approximate determination of fiber dopants.

  12. Large field distributed aperture laser semiactive angle measurement system design with imaging fiber bundles.

    PubMed

    Xu, Chunyun; Cheng, Haobo; Feng, Yunpeng; Jing, Xiaoli

    2016-09-01

    A type of laser semiactive angle measurement system is designed for target detecting and tracking. Only one detector is used to detect target location from four distributed aperture optical systems through a 4×1 imaging fiber bundle. A telecentric optical system in image space is designed to increase the efficiency of imaging fiber bundles. According to the working principle of a four-quadrant (4Q) detector, fiber diamond alignment is adopted between an optical system and a 4Q detector. The structure of the laser semiactive angle measurement system is, we believe, novel. Tolerance analysis is carried out to determine tolerance limits of manufacture and installation errors of the optical system. The performance of the proposed method is identified by computer simulations and experiments. It is demonstrated that the linear region of the system is ±12°, with measurement error of better than 0.2°. In general, this new system can be used with large field of view and high accuracy, providing an efficient, stable, and fast method for angle measurement in practical situations.

  13. Study on the method to test large-aperture hyperboloid convex mirror

    NASA Astrophysics Data System (ADS)

    Meng, Xiaohui; Dong, Huiwen; Guo, Wen; Wang, Huijun

    2014-08-01

    There are numerous reflecting optical system designs that call for large-aperture convex surfaces, such as secondary mirror in on-axis three mirror anastigmatic (TMA). Several methods to test high accuracy hyperboloid convex surfaces are introduced separately in this paper. A kind of arrangement is chosen to test a surface with diameter of 420mm, radius of 1371mm, and conic K -2.1229. The CGH compensator for testing is designed, which is made up of illumination lens and hologram test plate with designed residual wavefront aberration less than 0.001λ (RMS). The second transmitted method that is equipped with a technical flat surface coating by Ag film in the bottom of surface mirror under test, which form an auto-collimation optical system to eliminate the aberration. The Hindle-Simpson test that requires a larger meniscus lens to compensate the optical aberration, and the designed result of optical test system is less than 0.0016λ. Contrasting the CGH compensator and the second transmitted method, the Hindle-Simpson testing method has the advantage of it is easily to manufacture and adjust; meanwhile the test result is stable and has been less affected by the environment. It has been found that the method is rational and reliable, and it can fulfill the requirement of manufacturing and testing process for hyperboloid convex mirrors.

  14. Large-Aperture Wide-Bandwidth Anti-Reflection-Coated Silicon Lenses for Millimeter Wavelengths

    NASA Technical Reports Server (NTRS)

    Datta, R.; Munson, C. D.; Niemack, M. D.; McMahon, J. J.; Britton, J.; Wollack, E. J.; Beall, J.; Devlin, M. J.; Fowler, J.; Gallardo, P.; Hubmayr, J.; Irwin, K.; Newburgh, L.; Nibarger, J. P.; Page, L.; Quijada, M. A.; Schmitt, B. L.; Staggs, S. T.; Thornton, R.; Zhang, L.

    2013-01-01

    The increasing scale of cryogenic detector arrays for sub-millimeter and millimeter wavelength astrophysics has led to the need for large aperture, high index of refraction, low loss, cryogenic refracting optics. Silicon with n = 3.4, low loss, and relatively high thermal conductivity is a nearly optimal material for these purposes, but requires an antireflection (AR) coating with broad bandwidth, low loss, low reflectance, and a matched coffecient of thermal expansion. We present an AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three axis silicon dicing saw. These features constitute a metamaterial that behaves as a simple dielectric coating. We have fabricated and coated silicon lenses as large as 33.4 cm in diameter with coatings optimized for use between 125-165 GHz. Our design reduces average reflections to a few tenths of a percent for angles of incidence up to 30 deg. with low cross-polarization. We describe the design, tolerance, manufacture, and measurements of these coatings and present measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures. This coating and lens fabrication approach is applicable from centimeter to sub-millimeter wavelengths and can be used to fabricate coatings with greater than octave bandwidth.

  15. Large-aperture Wide-bandwidth Antireflection-coated Silicon Lenses for Millimeter Wavelengths

    NASA Technical Reports Server (NTRS)

    Datta, R.; Munson, C. D.; Niemack, M. D.; McMahon, J. J.; Britton, J.; Wollack, Edward J.; Beall, J.; Devlin, M. J.; Fowler, J.; Gallardo, P.; Hubmayr, J.; Irwin, K.; Newburgh, L.; Nibarger, J. P.; Page, L.; Quijada, Manuel A.; Schmitt, B. L.; Staggs, S. T.; Thornton, R.; Zhang, L.

    2013-01-01

    The increasing scale of cryogenic detector arrays for submillimeter and millimeter wavelength astrophysics has led to the need for large aperture, high index of refraction, low loss, cryogenic refracting optics. Silicon with n 3.4, low loss, and high thermal conductivity is a nearly optimal material for these purposes but requires an antireflection (AR) coating with broad bandwidth, low loss, low reflectance, and a matched coefficient of thermal expansion. We present an AR coating for curved silicon optics comprised of subwavelength features cut into the lens surface with a custom three-axis silicon dicing saw. These features constitute a metamaterial that behaves as a simple dielectric coating.We have fabricated silicon lenses as large as 33.4 cm in diameter with micromachined layers optimized for use between 125 and 165 GHz. Our design reduces average reflections to a few tenths of a percent for angles of incidence up to 30deg with low cross polarization.We describe the design, tolerance, manufacture, and measurements of these coatings and present measurements of the optical properties of silicon at millimeter wavelengths at cryogenic and room temperatures. This coating and lens fabrication approach is applicable from centimeter to submillimeter wavelengths and can be used to fabricate coatings with greater than octave bandwidth.

  16. Advanced Technology Large-Aperture Space Telescope: Science Drivers and Technology Developments

    NASA Technical Reports Server (NTRS)

    Postman, Marc; Brown, Tom; Sembach, Kenneth; Glavallsco, Mauro; Traub, Wesley; Stapelfeldt, Karl; Calzetti, Daniela; Oegerle, William; Rich, R. Michael; Stahl, H. Philip; Tumlinson, Jason; Mountain, Matt; Soummer, Remi; Hyde, Tupper

    2012-01-01

    The Advanced Technology Large-Aperture Space Telescope (ATLAST) is a concept for an 8- to 16-m ultraviolet optical near Infrared space observatory for launch in the 2025 to 2030 era. ATLAST will allow astronomers to answer fundamental questions at the forefront of modern astrophysics, including: Is there life elsewhere in the Galaxy? We present a range of science drivers and the resulting performance requirements for ATLAST (8- to 16-marcsec angular resolution, diffraction limited imaging at 0.5 micron wavelength, minimum collecting area of 45 sq m, high sensitivity to light wavelengths from 0.1 to 2.4 micron, high stability in wavefront sensing and control). We also discuss the priorities for technology development needed to enable the construction of ATLAST for a cost that is comparable to that of current generation observatory-class space missions.

  17. Interference data correction methods for lunar observation with a large-aperture static imaging spectrometer.

    PubMed

    Zhang, Geng; Wang, Shuang; Li, Libo; Hu, Xiuqing; Hu, Bingliang

    2016-11-01

    The lunar spectrum has been used in radiometric calibration and sensor stability monitoring for spaceborne optical sensors. A ground-based large-aperture static image spectrometer (LASIS) can be used to acquire the lunar spectral image for lunar radiance model improvement when the moon orbits over its viewing field. The lunar orbiting behavior is not consistent with the desired scanning speed and direction of LASIS. To correctly extract interferograms from the obtained data, a translation correction method based on image correlation is proposed. This method registers the frames to a reference frame to reduce accumulative errors. Furthermore, we propose a circle-matching-based approach to achieve even higher accuracy during observation of the full moon. To demonstrate the effectiveness of our approaches, experiments are run on true lunar observation data. The results show that the proposed approaches outperform the state-of-the-art methods.

  18. Advanced Technology Large-Aperture Space Telescope: Science Drivers and Technology Developments

    NASA Technical Reports Server (NTRS)

    Postman, Marc; Brown, Tom; Sembach, Kenneth; Glavallsco, Mauro; Traub, Wesley; Stapelfeldt, Karl; Calzetti, Daniela; Oegerle, William; Rich, R. Michael; Stahl, H. Philip; hide

    2012-01-01

    The Advanced Technology Large-Aperture Space Telescope (ATLAST) is a concept for an 8- to 16-m ultraviolet optical near Infrared space observatory for launch in the 2025 to 2030 era. ATLAST will allow astronomers to answer fundamental questions at the forefront of modern astrophysics, including: Is there life elsewhere in the Galaxy? We present a range of science drivers and the resulting performance requirements for ATLAST (8- to 16-marcsec angular resolution, diffraction limited imaging at 0.5 micron wavelength, minimum collecting area of 45 sq m, high sensitivity to light wavelengths from 0.1 to 2.4 micron, high stability in wavefront sensing and control). We also discuss the priorities for technology development needed to enable the construction of ATLAST for a cost that is comparable to that of current generation observatory-class space missions.

  19. THE BALLOON-BORNE LARGE APERTURE SUBMILLIMETER TELESCOPE (BLAST) 2006: CALIBRATION AND FLIGHT PERFORMANCE

    SciTech Connect

    Truch, Matthew D. P.; Devlin, Mark J.; Dicker, Simon R.; Klein, Jeff; Ade, Peter A. R.; Griffin, Matthew; Hargrave, Peter C.; Mauskopf, Philip; Moncelsi, Lorenzo; Pascale, Enzo; Bock, James J.; Chapin, Edward L.; Halpern, Mark; Marsden, Gaelen; Gundersen, Joshua O.; Hughes, David H.; Martin, Peter G.; Netterfield, C. Barth; Olmi, Luca; Patanchon, Guillaume

    2009-12-20

    The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) operated successfully during a 250 hr flight over Antarctica in 2006 December (BLAST06). As part of the calibration and pointing procedures, the red hypergiant star VY CMa was observed and used as the primary calibrator. Details of the overall BLAST06 calibration procedure are discussed. The 1sigma uncertainty on the absolute calibration is accurate to 9.5%, 8.7%, and 9.2% at the 250, 350, and 500 mum bands, respectively. The errors are highly correlated between bands resulting in much lower errors for the derived shape of the 250-500 mum continuum. The overall pointing error is < 5'' rms for the 36'', 42'', and 60'' beams. The performance of optics and pointing systems is discussed.

  20. Large-aperture high-resolution X-ray collimator for the Solar Maximum Mission

    NASA Technical Reports Server (NTRS)

    Nobles, R. A.; Acton, L. W.; Joki, E. G.; Leibacher, J. W.; Peterson, R. C.

    1980-01-01

    A description is presented of a flight-qualified large-aperture 12 x 12-arcsec angular resolution multigrid X-ray collimator developed for the Solar Maximum Mission (SMM) flat crystal spectrometer. This collimator, designed for the 1.4-22.4-A wavelength range, utilizes an optical bench/metering structure to align and support prealigned grid subassemblies. The optical bench is a lightweight, rigid, and stable aluminum honeycomb structure. The grids are of a compound and bimetallic design, having 63.5-micron square holes on an 88.9-micron spacing in 8-micron thick gold, which is in turn supported by a 76-micron thick Invar grid having 600-micron square holes on a 739-micron spacing. The small apertures in the gold provide the 12-arcsec collimation with the Invar grids providing wide angle off-axis blocking out to an approximately 35 arcmin view angle. The collimator has seven individual channels, four of a 5.1- x 10-cm area and three of a 1.3- x 10-cm area. Laboratory measurements gave an average angular resolution of 12.5 arcsec FWHM with 0.259 transmission for the large-area channels and 12.0 arcsec and 0.200 transmission for the small-area channels. A thermal filter composed of two layers of approximately 1000-A thick aluminum prevents solar heating of the front collimator grids by absorbing longer wavelength radiation while passing most of the X radiation in the band of interest.

  1. The scaling relationship between telescope cost and aperture size for very large telescopes

    NASA Technical Reports Server (NTRS)

    van Belle, Gerard T.; Meinel, Aden Baker; Meinel, Marjorie Pettit

    2004-01-01

    Cost data for ground-based telescopes of the last century are analyzed for trends in the relationship between aperture size and cost. We find that for apertures built prior to 1980, costs scaled as aperture size to the 2.8 power, which is consistent with the precious finding of Meinel (1978). After 1980, 'traditional' monolithic mirror telescope costs have scaled as aperture to the 2.5 power. The large multiple mirror telescopes built or in construction during this time period (Keck, LBT, GTC) appear to deviate from this relationship with significant cost savings as a result, although it is unclear what power law such structures follow. We discuss the implications of the current cost-aperture size data on the proposed large telescope projects of the next ten to twenty years. Structures that naturally tend towards the 2.0 power in the cost-aperture relationship will be the favorable choice for future extremely large apertures; out expectation is that space-based structures will ultimately gain economic advantage over ground-based ones.

  2. Analysis and simulation of aperture-sizing strategies with partial adaptive optics

    NASA Astrophysics Data System (ADS)

    Tyson, Robert K.

    1994-05-01

    The central core intensity of a stellar image observed by a ground-based telescope can be maximized by a judicious balancing of the adaptive optics system and the size of the telescope entrance aperture. For a given aperture, increasing the number of degrees of adaptive optics turbulence compensation will maximize the brightness of the central core. However, for an observatory using an adaptive optics system with a fixed number of degrees-of-freedom, the largest aperture available will not necessarily result in a maximized image central core. The negative effects of atmospheric turbulence, roughly proportional to e(superscript -(D/r(subscript o))(superscript 5/3)), cannot always be compensated by the increased light gathering ability of a larger aperture (proportional to D(superscript 2)). It is shown and verified through simulation that the optimum aperture diameter is a function of N(superscript p) r(subscript o) where N is the number of adaptive optics degrees of freedom and r(subscript o) is the seeing cell size. The simulations show that the exponent p is related to the control algorithm or, more precisely, the figure-of-merit used to drive the deformable mirror actuators. Optimizing the useful aperture of the telescope/adaptive optics system is a strategy that can make use of the variation in site seeing conditions and benefit the astronomer by increasing the available number of observable science objects or reducing the observing time.

  3. Large-aperture, tapered fiber-coupled, 10-kHz particle-image velocimetry.

    PubMed

    Hsu, Paul S; Roy, Sukesh; Jiang, Naibo; Gord, James R

    2013-02-11

    We demonstrate the design and implementation of a fiber-optic beam-delivery system using a large-aperture, tapered step-index fiber for high-speed particle-image velocimetry (PIV) in turbulent combustion flows. The tapered fiber in conjunction with a diffractive-optical-element (DOE) fiber-optic coupler significantly increases the damage threshold of the fiber, enabling fiber-optic beam delivery of sufficient nanosecond, 532-nm, laser pulse energy for high-speed PIV measurements. The fiber successfully transmits 1-kHz and 10-kHz laser pulses with energies of 5.3 mJ and 2 mJ, respectively, for more than 25 min without any indication of damage. It is experimentally demonstrated that the tapered fiber possesses the high coupling efficiency (~80%) and moderate beam quality for PIV. Additionally, the nearly uniform output-beam profile exiting the fiber is ideal for PIV applications. Comparative PIV measurements are made using a conventionally (bulk-optic) delivered light sheet, and a similar order of measurement accuracy is obtained with and without fiber coupling. Effective use of fiber-coupled, 10-kHz PIV is demonstrated for instantaneous 2D velocity-field measurements in turbulent reacting flows. Proof-of-concept measurements show significant promise for the performance of fiber-coupled, high-speed PIV using a tapered optical fiber in harsh laser-diagnostic environments such as those encountered in gas-turbine test beds and the cylinder of a combustion engine.

  4. ATLAST-9.2: A Deployable Large Aperture UVOIR Space Telescope

    NASA Technical Reports Server (NTRS)

    Oegerle, William R.; Feinberg, L.; Purves, L.; Hyde, T.; Thronson, H.; Townsend, J.; Postman, M.; Bolcar, M.; Budinoff, J.; Dean, B.; Clampin, N.; Ebbets, D.; Gong, Q.; Gull, T.; Howard, J.; Jones, A.; Lyon, R.; Pasquale, B.; Perrygo, C.; Smith, S.; Thompson, P.; Woodgate, B.

    2010-01-01

    We present the results of a study of a deployable version of the Advanced Technology Large Aperture Space Telescope (ATLAST) that could be launched on an Evolved Expendable Launch Vehicle (EELV). ATLAST is a concept for a next-generation UVOIR observatory to follow HST and JWST. The observatory retains significant heritage from JWST, thereby taking advantage of technologies and engineering already developed for that mission. At the same time, we have identified several design changes to the JWST architecture, some of which are required due to the demanding wavefront error requirements at visible wavelengths. The optical telescope assembly has a segmented 9.2-meter aperture and consists of 36 hexagonal glass mirrors, each of which is I.3l5m in size (flat-to-flat). The telescope can be folded to fit in the 6.5m fairing on the planned upgrade to the Delta-IV heavy launch vehicle. Near-real time wavefront sensing and control is performed on-board the telescope using stars in the field of view to deliver diffraction limited imaging performance at 500nm wavelength. The optical design of the telescope provides an 8x20 arcmin FOV in which 4-5 instruments can be accommodated, plus fine guidance and wavefront sensors. Unlike JWST, the OTA sits at the end of a multi-gimbaled arm, allowing pitch and roll motion, and is isolated from the sunshield and spacecraft bus by an active isolation system. Our design permits servicing in order to extend the life of the observatory.

  5. ATLAST-9.2: A Deployable Large Aperture UVOIR Space Telescope

    NASA Technical Reports Server (NTRS)

    Oegerle, William R.; Feinberg, L.; Purves, L.; Hyde, T.; Thronson, H.; Townsend, J.; Postman, M.; Bolcar, M.; Budinoff, J.; Dean, B.; hide

    2010-01-01

    We present the results of a study of a deployable version of the Advanced Technology Large Aperture Space Telescope (ATLAST) that could be launched on an Evolved Expendable Launch Vehicle (EELV). ATLAST is a concept for a next-generation UVOIR observatory to follow HST and JWST. The observatory retains significant heritage from JWST, thereby taking advantage of technologies and engineering already developed for that mission. At the same time, we have identified several design changes to the JWST architecture, some of which are required due to the demanding wavefront error requirements at visible wavelengths. The optical telescope assembly has a segmented 9.2-meter aperture and consists of 36 hexagonal glass mirrors, each of which is I.3l5m in size (flat-to-flat). The telescope can be folded to fit in the 6.5m fairing on the planned upgrade to the Delta-IV heavy launch vehicle. Near-real time wavefront sensing and control is performed on-board the telescope using stars in the field of view to deliver diffraction limited imaging performance at 500nm wavelength. The optical design of the telescope provides an 8x20 arcmin FOV in which 4-5 instruments can be accommodated, plus fine guidance and wavefront sensors. Unlike JWST, the OTA sits at the end of a multi-gimbaled arm, allowing pitch and roll motion, and is isolated from the sunshield and spacecraft bus by an active isolation system. Our design permits servicing in order to extend the life of the observatory.

  6. Automated interferometric synthetic aperture microscopy and computational adaptive optics for improved optical coherence tomography.

    PubMed

    Xu, Yang; Liu, Yuan-Zhi; Boppart, Stephen A; Carney, P Scott

    2016-03-10

    In this paper, we introduce an algorithm framework for the automation of interferometric synthetic aperture microscopy (ISAM). Under this framework, common processing steps such as dispersion correction, Fourier domain resampling, and computational adaptive optics aberration correction are carried out as metrics-assisted parameter search problems. We further present the results of this algorithm applied to phantom and biological tissue samples and compare with manually adjusted results. With the automated algorithm, near-optimal ISAM reconstruction can be achieved without manual adjustment. At the same time, the technical barrier for the nonexpert using ISAM imaging is also significantly lowered.

  7. Large aperture laser beam alignment system based on far field sampling technique

    NASA Astrophysics Data System (ADS)

    Zhang, J. C.; Liu, D. Z.; Ouyang, X. P.; Kang, J.; Xie, X. L.; Zhou, J.; Gong, L.; Zhu, B. Q.

    2016-11-01

    Laser beam alignment is very important for high-power laser facility. Long laser path and large-aperture lens for alignment are generally used, while the proposed alignment system with a wedge by far-field sampling technique reduces both space and cost requirements. General alignment system for large-aperture laser beam is long in distance and large in volum because of taking near-field sampling technique. With the development of laser fusion facilities, the space for alignment system is limited. A new alignment system for large-aperture laser beam is designed to save space and reduce operating costs. The new alignment for large-aperture laser beam with a wedge is based on far-field sampling technique. The wedge is placed behind the spatial filter to reflect some laser beam as signal light for alignment. Therefore, laser beam diameter in alignment system is small, which can save space for the laser facility. Comparing to general alignment system for large-aperture laser beam, large-aperture lenses for near-field and far-field sampling, long distance laser path are unnecessary for proposed alignment system, which saves cost and space greatly. This alignment system for large-aperture laser beam has been demonstrated well on the Muliti-PW Facility which uses the 7th beam of the SG-Ⅱ Facility as pump source. The experimental results indicate that the average near-field alignment error is less than 1% of reference, and the average far-filed alignment error is less than 5% of spatial filter pinhole diameter, which meet the alignment system requirements for laser beam of Multi-PW Facility.

  8. Parasitic suppression in large aperture disk lasers employing liquid edge claddings.

    PubMed

    Guch, S

    1976-06-01

    A liquid edge cladding system for parasitic suppression in large aperture, high gain disk laser amplifiers has been developed and tested. A near-saturated aqueous solution of Znl(2) was employed for index-matching. Adequate fluorescence absorption was demonstrated using either dissolved NiCl(2) or chrome black oxide coating applied to the disk holder. Application of liquid cladding to a 20-cm aperture disk laser amplifier increased energy storage capability by approximately 20% over conventional solder glass claddings.

  9. Experimentally supported investigations into the optical performance of multi-aperture window concepts

    NASA Astrophysics Data System (ADS)

    Brooks, L. C.; Kalin, D. A.; Banish, M. R.

    1992-05-01

    An experimental and analytic investigation was undertaken to examine the optical performance of a multiaperture window concept for use in hypersonic, endoatmospheric vehicles. The window was simulated using a simple two-dimensional flat plate with multiple circular apertures. Analyses were performed to examine transmission, thermal emission, and aero-optic effects (image blur, jitter, and Strehl reduction). A series of imaging tests was conducted in both the short wave infrared (SWIR) and midwave infrared (MWIR) wavebands through the multi-aperture window and a monolithic (baseline) window. The images recorded through both window schemes were analyzed and compared to investigate the effects of multi-aperture windows on aero-optic performance. The results from these experiments could be used in a concept definition or trade study for potential optically guided vehicle systems.

  10. Detection of Luminescent Nanodiamonds Using a Scanning Near-Field Optical Microscope with an Aperture Probe

    NASA Astrophysics Data System (ADS)

    Shershulin, V. A.; Samoylenko, S. R.; Shenderova, O. A.; Vlasov, I. I.; Konov, V. I.

    2016-09-01

    Scanning near-fi eld optical microscopy (SNOM) with an aperture probe has been used to map the luminescence of isolated submicron diamond crystallites. 532-nm laser light was used to excite luminescence of nitrogen-vacancy (NV) centers. The sizes of the analyzed diamond crystallites were determined with an atomic-force microscope. The optical resolution for the lateral dimensions of the luminescing diamond crystallites was doubled on going from confocal luminescence microscopy to scanning near-fi eld optical microscopy with a 290-nm probe aperture diameter.

  11. Reflective Schmidt-Cassegrain system for large-aperture telescopes.

    PubMed

    Brychikhin, M N; Chkhalo, N I; Eikhorn, Ya O; Malyshev, I V; Pestov, A E; Plastinin, Yu A; Polkovnikov, V N; Rizvanov, A A; Salashchenko, N N; Strulya, I L; Toropov, M N

    2016-06-01

    A reflective modification of the Schmidt-Cassegrain system was built and tested. Ultraviolet (UV) and soft x-ray applications are discussed. The system consists of a planoid mirror with an aspheric profile and prime concave and secondary convex spherical mirrors. Spherical aberration in a wide field of view and astigmatism are compensated by the aspheric profile of the planoid. The main parameters of the scheme are as follows: an entrance aperture of 180 mm, a focal ratio F/3.2, an angular resolution better than 3'' (corresponding to a pixel size of a back-side illuminated CCD), a field of view of ±1.5° (2ω=3°) and a flat image field with a diameter of 30.4 mm. Due to the absence of chromatic aberrations and wide field of view, the scheme is of considerable interest for hyperspectral instruments. In particular, the operating range of the instruments can be expanded into vacuum UV and UV regions.

  12. Reconstruction in interferometric synthetic aperture microscopy: comparison with optical coherence tomography and digital holographic microscopy.

    PubMed

    Sheppard, Colin J R; Kou, Shan Shan; Depeursinge, Christian

    2012-03-01

    It is shown that the spatial frequencies recorded in interferometric synthetic aperture microscopy do not correspond to exact backscattering [as they do in unistatic synthetic aperture radar (SAR)] and that the reconstruction process based on SAR is therefore based on an approximation. The spatial frequency response is developed based on the three-dimensional coherent transfer function approach and compared with that in optical coherence tomography and digital holographic microscopy.

  13. Large optical glass lenses for ELTs

    NASA Astrophysics Data System (ADS)

    Hartmann, Peter; Jedamzik, Ralf

    2006-06-01

    ELTs will need large optical lenses for imaging optics and atmospheric dispersion correctors. The extreme dimensions of lenses considered in designs at present (up to 1.7 m diameter) pose severe challenges for the specification, production and inspection of the glass blanks. Possible maximum sizes, their very long production time, technical and economical conditions and probable restrictions are discussed. The inspection of glass blanks for ELT transmission optics can rely on methods already introduced for optical glass blanks of conventional sizes and for large mirror blanks of the glass-ceramic ZERODUR(r) for most of their properties. However, especially for the refractive index homogeneity a scale-up still has to be achieved. At present largest homogeneity interferometers have apertures about 500 to 600 mm. The development of larger ones is very time consuming, about 2 - 3 years. There is a need for a close agreement on the required capability of the measurement method between the optical designers and the supplier and to start soon with this since the optical lenses may turn out to be more critical in production than the segments for the primary mirrors.

  14. The research progress of large-aperture fused silica for high power laser

    NASA Astrophysics Data System (ADS)

    Shao, Zhufeng; Wang, Yufen; Xiang, Zaikui; Rao, Chuandong

    2016-03-01

    Because of its excellent optical performance, the fused silica is widely used in laser industry. In addition, the fused silica can withstand high power laser, due to its pure component, and the performance is most outstanding within all types of glasses. So fused silica can be used for optical lens in high power laser field. From the manufacturing process stand point, the fused silica can be categorized to four types: type Ⅰ, type Ⅱ, type Ⅲ, and type Ⅳ. The fused silica of type Ⅰand type Ⅱ is made through melting silica sand in graphite furnace or oxyhydrogen flame. There are many defects in these types of fused silica, for example, the air bubbles, inclusions and metallic impurity. The other two types are made by synthetic reaction of SiCl4 with water in oxyhydrogen or plasma flame. Both type Ⅲ and Ⅳ have excellent performance in transmittance and internal quality. However, type Ⅳof fused silica has disadvantage in small aperture and overall high manufacturing cost. Take the transmittance and internal quality into consideration, the type Ⅲ fused silica is the most suitable for large-aperture lens, and can withstand high power laser. The systemic studies of manufacturing process were done to improve the performance of type Ⅲ fused silica in various areas, for instance, the optical homogeneity, the stress birefringence, the absorption coefficient and the damage threshold. There are four steps in manufacturing process of type Ⅲ fused silica, ingot production, reshaping, annealing and cold-working. The critical factors of ingot production, like the flame of burner and the structure of furnace, were deeply studied in this paper to improve the performance of fused silica. On the basis of the above research, the performance and quality of the fused silica measured up to advanced world levels. For instance, the result of optical homogeneity can be controlled to 2~5 ppm, the stress birefringence is better than 4 nm/cm, the absorption coefficient

  15. LCLS X-ray mirror measurements using a large aperture visible light interferometer

    SciTech Connect

    McCarville, T; Soufli, R; Pivovaroff, M

    2011-03-02

    Synchrotron or FEL X-ray mirrors are required to deliver an X-ray beam from its source to an experiment location, without contributing significantly to wave front distortion. Accurate mirror figure measurements are required prior to installation to meet this intent. This paper describes how a 300 mm aperture phasing interferometer was calibrated to <1 nm absolute accuracy and used to mount and measure 450 mm long flats for the Linear Coherent Light Source (LCLS) at Stanford Linear Accelerator Center. Measuring focus mirrors with an interferometer requires additional calibration, because high fringe density introduces systematic errors from the interferometer's imaging optics. This paper describes how these errors can be measured and corrected. The calibration approaches described here apply equally well to interferometers larger than 300 mm aperture, which are becoming more common in optics laboratories. The objective of this effort was to install LCLS flats with < 10 nm of spherical curvature, and < 2 nm rms a-sphere. The objective was met by measuring the mirrors after fabrication, coating and mounting, using a 300 mm aperture phasing interferometer calibrated to an accuracy < 1 nm. The key to calibrating the interferometer accurately was to sample the error using independent geometries that are available. The results of those measurements helped identify and reduce calibration error sources. The approach used to measure flats applies equally well to focus mirrors, provided an additional calibration is performed to measure the error introduced by fringe density. This calibration has been performed on the 300 mm aperture interferometer, and the measurement correction was evaluated for a typical focus mirror. The 300 mm aperture limitation requires stitching figure measurements together for many X-ray mirrors of interest, introducing another possible error source. Stitching is eliminated by applying the calibrations described above to larger aperture instruments

  16. 8 Meter Advanced Technology Large-Aperture Space Telescope (ATLAST-8m)

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip

    2010-01-01

    ATLAST-8m (Advanced Technology Large Aperture Space Telescope) is a proposed 8-meter monolithic UV/optical/NIR space observatory (wavelength range 110 to 2500 nm) to be placed in orbit at Sun-Earth L2 by NASA's planned Ares V heavy lift vehicle. Given its very high angular resolution (15 mas @ 500 nm), sensitivity and performance stability, ATLAST-8m is capable of achieving breakthroughs in a broad range of astrophysics including: Is there life elsewhere in the Galaxy? An 8-meter UVOIR observatory has the performance required to detect habitability (H2O, atmospheric column density) and biosignatures (O2, O3, CH4) in terrestrial exoplanet atmospheres, to reveal the underlying physics that drives star formation, and to trace the complex interactions between dark matter, galaxies, and intergalactic medium. The ATLAST Astrophysics Strategic Mission Concept Study developed a detailed point design for an 8-m monolithic observatory including optical design; structural design/analysis including primary mirror support structure, sun shade and secondary mirror support structure; thermal analysis; spacecraft including structure, propulsion, GN&C, avionics, power systems and reaction wheels; mass and power budgets; and system cost. The results of which were submitted by invitation to NRC's 2010 Astronomy & Astrophysics Decadal Survey.

  17. Thermal Analysis of the Advanced Technology Large Aperture Space Telescope (ATLAST) 8 Meter Primary Mirror

    NASA Technical Reports Server (NTRS)

    Hornsby, Linda; Stahl, H. Philip; Hopkins, Randall C.

    2010-01-01

    The Advanced Technology Large Aperture Space Telescope (ATLAST) preliminary design concept consists of an 8 meter diameter monolithic primary mirror enclosed in an insulated, optical tube with stray light baffles and a sunshade. ATLAST will be placed in orbit about the Sun-Earth L2 and will experience constant exposure to the sun. The insulation on the optical tube and sunshade serve to cold bias the telescope which helps to minimize thermal gradients. The primary mirror will be maintained at 280K with an active thermal control system. The geometric model of the primary mirror, optical tube, sun baffles, and sunshade was developed using Thermal Desktop(R) SINDA/FLUINT(R) was used for the thermal analysis and the radiation environment was analyzed using RADCAD(R). A XX node model was executed in order to characterize the static performance and thermal stability of the mirror during maneuvers. This is important because long exposure observations, such as extra-solar terrestrial planet finding and characterization, require a very stable observatory wave front. Steady state thermal analyses served to predict mirror temperatures for several different sun angles. Transient analyses were performed in order to predict thermal time constant of the primary mirror for a 20 degree slew or 30 degree roll maneuver. This paper describes the thermal model and provides details of the geometry, thermo-optical properties, and the environment which influences the thermal performance. All assumptions that were used in the analysis are also documented. Parametric analyses are summarized for design parameters including primary mirror coatings and sunshade configuration. Estimates of mirror heater power requirements are reported. The thermal model demonstrates results for the primary mirror heated from the back side and edges using a heater system with multiple independently controlled zones.

  18. Thermal Analysis of the Advanced Technology Large Aperture Space Telescope (ATLAST) 8 Meter Primary Mirror

    NASA Technical Reports Server (NTRS)

    Hornsby, Linda; Stahl, H. Philip; Hopkins, Randall C.

    2010-01-01

    The Advanced Technology Large Aperture Space Telescope (ATLAST) preliminary design concept consists of an 8 meter diameter monolithic primary mirror enclosed in an insulated, optical tube with stray light baffles and a sunshade. ATLAST will be placed in orbit about the Sun-Earth L2 and will experience constant exposure to the sun. The insulation on the optical tube and sunshade serve to cold bias the telescope which helps to minimize thermal gradients. The primary mirror will be maintained at 280K with an active thermal control system. The geometric model of the primary mirror, optical tube, sun baffles, and sunshade was developed using Thermal Desktop(R) SINDA/FLUINT(R) was used for the thermal analysis and the radiation environment was analyzed using RADCAD(R). A XX node model was executed in order to characterize the static performance and thermal stability of the mirror during maneuvers. This is important because long exposure observations, such as extra-solar terrestrial planet finding and characterization, require a very stable observatory wave front. Steady state thermal analyses served to predict mirror temperatures for several different sun angles. Transient analyses were performed in order to predict thermal time constant of the primary mirror for a 20 degree slew or 30 degree roll maneuver. This paper describes the thermal model and provides details of the geometry, thermo-optical properties, and the environment which influences the thermal performance. All assumptions that were used in the analysis are also documented. Parametric analyses are summarized for design parameters including primary mirror coatings and sunshade configuration. Estimates of mirror heater power requirements are reported. The thermal model demonstrates results for the primary mirror heated from the back side and edges using a heater system with multiple independently controlled zones.

  19. Thermal analysis of the Advanced Technology Large Aperture Space Telescope (ATLAST) 8-meter primary mirror

    NASA Astrophysics Data System (ADS)

    Hornsby, Linda; Hopkins, Randall C.; Stahl, H. Philip

    2010-07-01

    The Advanced Technology Large Aperture Space Telescope (ATLAST) preliminary design concept consists of an 8 meter diameter monolithic primary mirror enclosed in an insulated, optical tube with stray light baffles and a sunshade. ATLAST will be placed in orbit about the Sun-Earth L2 point and will experience constant exposure to the sun. The insulation on the optical tube and sunshade serve to cold bias the telescope which helps to minimize thermal gradients. The objective is to maintain the primary mirror at 280K with an active thermal control system. The geometric model of the primary mirror, optical tube, sun baffles, and sunshade was developed using Thermal Desktop®1. A detailed model of the primary mirror was required in order to characterize the static performance and thermal stability of the mirror during maneuvers. This is important because long exposure observations, such as extra-solar terrestrial planet finding and characterization, require a very stable observatory wave front. Steady state thermal analyses served to predict mirror temperatures for several different sun angles. Transient analyses were performed in order to predict thermal time constant of the primary mirror for a 20 degree slew and a 30 degree roll maneuver. This paper describes the thermal model and provides details of the geometry, thermo-optical properties, and the solar environment that influences the thermal performance. All assumptions that were used in the analysis are also documented. Estimates of mirror heater power requirements are reported. The thermal model is used to predict gradients across and through the primary mirror using an idealized boundary temperature on the back and sides of the mirror of 280 K.

  20. Large-Aperture, Three Mirror Telescopes for Near-Earth

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; McGraw, J.

    In this era when Space Situational Awareness (SSA) is a national priority and optical-infrared telescopic sensor development is underway, cost-benefit analyses of competing approaches are necessary and appropriate. The DOD is presently investing in a new three-mirror telescope for SSA. At the same time, the Air Force, various universities and private research organizations are either studying or building wide-field telescopes with similar capabilities, but in most cases, at a significantly lower cost. Much of the expense for the DOD system appears driven by certain design choices which were advertised as necessary to fulfill the mission. Design details which would allow an independent analysis have not been published and no public comparison with other approaches is known to exist. Most telescope designs however, can be closely approximated from their optical configuration and imaging performance specifications. An optical designer will tell you that field curvature is one of the five monochromatic aberrations which they try to eliminate. The fact that one DOD development effort considers field curvature a design feature immediately draws attention to the project. This coupled with the paucity of published information and the very high development cost makes this program irresistible for comparison with competing approaches. This paper examines the likely design and performance of a proxy telescope intended to find NEOs, compares and contrasts that telescope with similar, but lower cost on-going projects, and examines the predictable impacts of reproducing such a telescope and placing multiple copies around the globe. The study primarily concentrates on performance measured in terms of search rate in square degrees per hour vs. object visual magnitude. Other considerations such as cost, transportability, availability of replacement components and ease of installation are also considered.

  1. RF/optical shared aperture for high availability wideband communication RF/FSO links

    DOEpatents

    Ruggiero, Anthony J; Pao, Hsueh-yuan; Sargis, Paul

    2014-04-29

    An RF/Optical shared aperture is capable of transmitting and receiving optical signals and RF signals simultaneously. This technology enables compact wide bandwidth communications systems with 100% availability in clear air turbulence, rain and fog. The functions of an optical telescope and an RF reflector antenna are combined into a single compact package by installing an RF feed at either of the focal points of a modified Gregorian telescope.

  2. RF/optical shared aperture for high availability wideband communication RF/FSO links

    DOEpatents

    Ruggiero, Anthony J; Pao, Hsueh-yuan; Sargis, Paul

    2015-03-24

    An RF/Optical shared aperture is capable of transmitting and receiving optical signals and RF signals simultaneously. This technology enables compact wide bandwidth communications systems with 100% availability in clear air turbulence, rain and fog. The functions of an optical telescope and an RF reflector antenna are combined into a single compact package by installing an RF feed at either of the focal points of a modified Gregorian telescope.

  3. Large aperture freeform VIS telescope with smart alignment approach

    NASA Astrophysics Data System (ADS)

    Beier, Matthias; Fuhlrott, Wilko; Hartung, Johannes; Holota, Wolfgang; Gebhardt, Andreas; Risse, Stefan

    2016-07-01

    The development of smart alignment and integration strategies for imaging mirror systems to be used within astronomical instrumentation are especially important with regard to the increasing impact of non-rotationally symmetric optics. In the present work, well-known assembly approaches preferentially applied in the course of infrared instrumentation are transferred to visible applications and are verified during the integration of an anamorphic imaging telescope breadboard. The four mirror imaging system is based on a modular concept using mechanically fixed arrangements of each two freeform surfaces, generated by servo assisted diamond machining and corrected using Magnetorheological Finishing as a figuring and smoothing step. Surface testing include optical CGH interferometry as well as tactile profilometry and is conducted with respect to diamond milled fiducials at the mirror bodies. A strict compliance of surface referencing during all significant fabrication steps allow for an easy integration and direct measurement of the system's wave aberration after initial assembly. The achievable imaging performance, as well as influences of the tight tolerance budget and mid-spatial frequency errors, are discussed and experimentally evaluated.

  4. Large aperture deformable mirror with a transferred single-crystal silicon membrane actuated using large-stroke PZT Unimorph Actuators

    NASA Technical Reports Server (NTRS)

    Hishinumat, Yoshikazu; Yang, Eui - Hyeok (EH)

    2005-01-01

    We have demonstrated a large aperture (50 mm x 50 mm) continuous membrane deformable mirror (DM) with a large-stroke piezoelectric unimorph actuator array. The DM consists of a continuous, large aperture, silicon membrane 'transferred' in its entirety onto a 20 x 20 piezoelectric unimorph actuator array. A PZT unimorph actuator, 2.5 mm in diameter with optimized PZT/Si thickness and design showed a deflection of 5.7 [m at 20V. An assembled DM showed an operating frequency bandwidth of 30 kHz and influence function of approximately 30%.

  5. Large aperture deformable mirror with a transferred single-crystal silicon membrane actuated using large-stroke PZT Unimorph Actuators

    NASA Technical Reports Server (NTRS)

    Hishinumat, Yoshikazu; Yang, Eui - Hyeok (EH)

    2005-01-01

    We have demonstrated a large aperture (50 mm x 50 mm) continuous membrane deformable mirror (DM) with a large-stroke piezoelectric unimorph actuator array. The DM consists of a continuous, large aperture, silicon membrane 'transferred' in its entirety onto a 20 x 20 piezoelectric unimorph actuator array. A PZT unimorph actuator, 2.5 mm in diameter with optimized PZT/Si thickness and design showed a deflection of 5.7 [m at 20V. An assembled DM showed an operating frequency bandwidth of 30 kHz and influence function of approximately 30%.

  6. The research of filtering on images with noises of the three-mirror aperture optical system

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Wu, Quanying; Fan, Junliu; Wang, Youqing

    2014-11-01

    In order to eliminate the noise in images acquired by the sparse aperture system, the modeling and filtering of electrical and optical noise are analyzed by the case of three-mirror aperture optical system. The study shows that the median filter can be applied to remove Gauss and salt & pepper noise, meanwhile high-pass filter with Gauss function can eliminate the influence of non-uniform illuminating on imaging. The Lucy-Richardson algorithm is used to restore the image, by which the resolution is heightened.

  7. NIF Large Optics Metrology Software: Description and Algorithms

    SciTech Connect

    Williams, W H

    2002-10-15

    Several software packages have been developed for use by NIF large optics vendors during production of NIF optics. These packages allow specific comparison of the interferometer measurements done on optics against the wavefront requirements for those optics, as given on relevant drawings. This document outlines the various packages, and their specific applications, and describes in some detail the calculational algorithms used. It is intended as the primary reference document for the codes (aside from the source codes themselves). In order to ensure good laser beam quality, NIF requires that all large optics be measured with an interferometer to monitor how that optic will affect beam wavefront quality and focusability. Various specifications for transmitted wavefront (TWF) and reflected wavefront (RWF) for the full-aperture parts, and for various sub-apertures, are given on the large optics drawings. For reference, a summary of the various specifications for the NIF large optics is given in Figure 1. Each large optic in production will be measured against some of these specifications. Other specifications will be monitored in a 'process validation' fashion by measuring a representative sample of parts to assure the process is yielding parts which pass specification. This document will focus on the specifications requiring measurements on every part. This document will not go into detail concerning the procedures and limitations of the measurements themselves.

  8. The Advanced Technology Large-Aperture Space Telescope (ATLAST) Technology Roadmap

    NASA Technical Reports Server (NTRS)

    Stahle, Carl; Balasubramanian, K.; Bolcar, M.; Clampin, M.; Feinberg, L.; Hartman, K.; Mosier, C.; Quijada, M.; Rauscher, B.; Redding, D.; Shaklan, S.; Stahl, P.; Thronson, H.

    2014-01-01

    We present the key technologies and capabilities that will enable a future, large-aperture ultravioletopticalinfrared (UVOIR) space observatory. These include starlight suppression systems, vibration isolation and control systems, lightweight mirror segments, detector systems, and mirror coatings. These capabilities will provide major advances over current and near-future observatories for sensitivity, angular resolution, and starlight suppression. The goals adopted in our study for the starlight suppression system are 10-10 contrast with an inner working angle of 40 milliarcsec and broad bandpass. We estimate that a vibration and isolation control system that achieves a total system vibration isolation of 140 dB for a vibration-isolated mass of 5000 kg is required to achieve the high wavefront error stability needed for exoplanet coronagraphy. Technology challenges for lightweight mirror segments include diffraction-limited optical quality and high wavefront error stability as well as low cost, low mass, and rapid fabrication. Key challenges for the detector systems include visible-blind, high quantum efficiency UV arrays, photon counting visible and NIR arrays for coronagraphic spectroscopy and starlight wavefront sensing and control, and detectors with deep full wells with low persistence and radiation tolerance to enable transit imaging and spectroscopy at all wavelengths. Finally, mirror coatings with high reflectivity ( 90), high uniformity ( 1) and low polarization ( 1) that are scalable to large diameter mirror substrates will be essential for ensuring that both high throughput UV observations and high contrast observations can be performed by the same observatory.

  9. A Future Large-Aperture UVOIR Space Observatory: Key Technologies and Capabilities

    NASA Technical Reports Server (NTRS)

    Bolcar, Matthew Ryan; Stahle, Carl M.; Balasubramaniam, Kunjithapatham; Clampin, Mark; Feinberg, Lee D.; Mosier, Gary E.; Quijada, Manuel A.; Rauscher, Bernard J.; Redding, David C.; Rioux, Norman M.; hide

    2015-01-01

    We present the key technologies and capabilities that will enable a future, large-aperture ultravioletopticalinfrared (UVOIR) space observatory. These include starlight suppression systems, vibration isolation and control systems, lightweight mirror segments, detector systems, and mirror coatings. These capabilities will provide major advances over current and near-future observatories for sensitivity, angular resolution, and starlight suppression. The goals adopted in our study for the starlight suppression system are 10-10 contrast with an inner working angle of 20 milliarcsec and broad bandpass. We estimate that a vibration and isolation control system that achieves a total system vibration isolation of 140 dB for a vibration-isolated mass of 5000 kg is required to achieve the high wavefront error stability needed for exoplanet coronagraphy. Technology challenges for lightweight mirror segments include diffraction-limited optical quality and high wavefront error stability as well as low cost, low mass, and rapid fabrication. Key challenges for the detector systems include visible-blind, high quantum efficiency UV arrays, photon counting visible and NIR arrays for coronagraphic spectroscopy and starlight wavefront sensing and control, and detectors with deep full wells with low persistence and radiation tolerance to enable transit imaging and spectroscopy at all wavelengths. Finally, mirror coatings with high reflectivity ( 90), high uniformity ( 1) and low polarization ( 1) that are scalable to large diameter mirror substrates will be essential for ensuring that both high throughput UV observations and high contrast observations can be performed by the same observatory.

  10. Electro-Mechanical Simulation of a Large Aperture MOEMS Fabry-Perot Tunable Filter

    NASA Technical Reports Server (NTRS)

    Kuhn, Jonathan L.; Barclay, Richard B.; Greenhouse, Matthew A.; Mott, D. Brent; Satyapal, Shobita; Powers, Edward I. (Technical Monitor)

    2000-01-01

    We are developing a micro-machined electrostatically actuated Fabry-Perot tunable filter with a large clear aperture for application in high through-put wide-field imaging spectroscopy and lidar systems. In the first phase of this effort, we are developing key components based on coupled electro-mechanical simulations. In particular, the movable etalon plate design leverages high coating stresses to yield a flat surface in drum-head tension over a large diameter (12.5 mm). In this approach, the cylindrical silicon movable plate is back etched, resulting in an optically coated membrane that is suspended from a thick silicon support ring. Understanding the interaction between the support ring, suspended membrane, and coating is critical to developing surfaces that are flat to within stringent etalon requirements. In this work, we present the simulations used to develop the movable plate, spring suspension system, and electrostatic actuation mechanism. We also present results from tests of fabricated proof of concept components.

  11. Metrological characterization of a large aperture Fizeau for x-ray mirrors measurement

    NASA Astrophysics Data System (ADS)

    Vannoni, Maurizio; Freijo Martín, Idoia

    2015-06-01

    The European XFEL is a large facility under construction in Hamburg, Germany. It will provide a transversally fully coherent x-ray radiation with outstanding characteristics: high repetition rate (up to 2700 pulses with a 0.6 milliseconds long pulse train at 10Hz), short wavelength (down to 0.05 nm), short pulse (in the femtoseconds scale) and high average brilliance (1.61025 photons / s / mm2 / mrad2/ 0.1% bandwidth). Due to the very short wavelength and very high pulse energy, all the mirrors need to have high quality surface, to be very long, and at the same time to implement an effective cooling system. Matching these tight specifications and assessing them with high precision optical measurements is very challenging. In order to measure the mirrors and to characterize their interaction with the mechanical mounts, we equipped a Metrology Laboratory with a Large Aperture Fizeau. The system is a classical 100 mm diameter commercial Fizeau, with an additional expander providing a 300 mm diameter. Despite the commercial nature of the system, special care has been done in the polishing of the reference flats and in the expander quality. In this report, we show the preparation of the instrument, the calibration and the performance characterization, together with some preliminary results. We also describe the approach that we want to follow for the x-rays mirrors measurements. The final goal will be to characterize very long mirrors, almost 1 meter long, with nanometer accuracy.

  12. Development of PIAA Complex Mask Coronagraphs for large aperture ground-based telescopes

    NASA Astrophysics Data System (ADS)

    Newman, Kevin; Sirbu, Dan; Belikov, Ruslan; Guyon, Olivier

    2016-07-01

    The Phase Induced Amplitude Apodization Complex Mask Coronagraph (PIAACMC) is an architecture for directly observing extra-solar planets, and can achieve performance near the theoretical limits for any direct-detection instrument. The PIAACMC architecture includes aspheric PIAA optics, and a complex phase-shifting focal plane mask that provides a pi phase shift to a portion of the on-axis starlight. The phase-shifted starlight is forced to interfere destructively with the un-shifted starlight, causing the starlight to be eliminated, and allowing a region for high-contrast imaging near the star. The PIAACMC architecture can be designed for segmented and obscured apertures, so it is particularly well suited for ground-based observing with the next generation of large telescopes. There will be unique scientific opportunities for directly observing Earth-like planets around nearby low-mass stars. We will discuss design strategies for adapting PIAACMC for the next generation of large ground-based telescopes, and present progress on the development of the focal plane mask technology. We also present simulations of wave-front control with PIAACMC, and suggest directions to apply the coronagraph architecture to future telescopes.

  13. Large-aperture high-resolution x-ray collimator for the Solar Maximum Mission.

    PubMed

    Nobles, R A; Acton, L W; Joki, E G; Leibacher, J W; Peterson, R C

    1980-09-01

    A description is presented of a flight-qualified large-aperture 12 x 12-sec of arc angular resolution multigrid x-ray collimator developed for the Solar Maximum Mission (SMM) flat crystal spectrometer. This collimator, designed for the 1.4-22.4-A wavelength range, utilizes an optical bench/metering structure to align and support prealigned grid subassemblies. One advantage of this scheme is to provide ready access to the grid subassemblies for inspection and/or servicing. The optical bench is a lightweight, rigid, and stable aluminum honeycomb structure. Aluminum is a viable material choice in this application because of the good thermal control expected in the SMM instrument package. The grids are of a compound and bimetallic design, having 63.5-microm square holes on an 88.9-microm spacing in 8-microm thick gold, which is in turn supported by a 76-microm thick Invar grid having 600-microm square holes on a 739-microm spacing. The small apertures in the gold provide the 12-sec of arc collimation with the Invar grids providing wide angle off-axis blocking out to an ~35-min of arc view angle. The collimator has seven individual channels, four of a 5.1- x 10-cm area and three of a 1.3- x 10-cm area. Laboratory measurements gave an average angular resolution of 12.5-sec of arc FWHM with 0.259 transmission for the large area channels and 12.0 sec of arc and 0.200 transmission for the small area channels. A hypothetical perfectly aligned collimator would have 12.5-sec of arc resolution and 0.300 transmission. A thermal filter composed of two layers of ~1000-A thick aluminum prevents solar heating of the front collimator grids by absorbing longer wavelength radiation while passing most of the x radiation in the band of interest. The filter was flight qualified by passing a protoflight acoustic test environment of 147-dB total sound level, 20-microN/M(2) reference, for 1-min duration.

  14. Synthesis of a large communications aperture using small antennas

    NASA Technical Reports Server (NTRS)

    Resch, George M.; Cwik, T. W.; Jamnejad, V.; Logan, R. T.; Miller, R. B.; Rogstad, Dave H.

    1994-01-01

    In this report we compare the cost of an array of small antennas to that of a single large antenna assuming both the array and single large antenna have equal performance and availability. The single large antenna is taken to be one of the 70-m antennas of the Deep Space Network. The cost of the array is estimated as a function of the array element diameter for three different values of system noise temperature corresponding to three different packaging schemes for the first amplifier. Array elements are taken to be fully steerable paraboloids and their cost estimates were obtained from commercial vendors. Array loss mechanisms and calibration problems are discussed. For array elements in the range 3 - 35 m there is no minimum in the cost versus diameter curve for the three system temperatures that were studied.

  15. Imaging properties of photon sieve with a large aperture

    NASA Astrophysics Data System (ADS)

    Gao, Zhong; Luo, Xiangang; Ma, Junxian; Fu, Yongqi; Du, Chunlei

    2008-06-01

    We report the optimization design and experimental results for the imaging properties of a photon sieve, which is formed on a layer of metal film supported by a thin glass substrate. As an example, we considered a micro-optical element with parameters of diameter D=50 mm, 3,564,290 hole number, and 10 μm minimum micro-hole diameter, which was designed and fabricated by means of surface machining technique in the lab. To evaluate its imaging performance, both on-axis and off-axis imaging experiments were carried out using the element. Compared to a Fresnel zone plate lens with the same feature size, the photon sieve has super imaging performance. Some quantitative analyses and initial qualitative explanations were given for the imaging characteristics.

  16. High numerical aperture diffractive optical elements for neutral atom quantum computing

    NASA Astrophysics Data System (ADS)

    Young, A. L.; Kemme, S. A.; Wendt, J. R.; Carter, T. R.; Samora, S.

    2013-03-01

    The viability of neutral atom based quantum computers is dependent upon scalability to large numbers of qubits. Diffractive optical elements (DOEs) offer the possibility to scale up to many qubit systems by enabling the manipulation of light to collect signal or deliver a tailored spatial trapping pattern. DOEs have an advantage over refractive microoptics since they do not have measurable surface sag, making significantly larger numerical apertures (NA) accessible with a smaller optical component. The smaller physical size of a DOE allows the micro-lenses to be placed in vacuum with the atoms, reducing aberration effects that would otherwise be introduced by the cell walls of the vacuum chamber. The larger collection angle accessible with DOEs enable faster quantum computation speeds. We have designed a set of DOEs for collecting the 852 nm fluorescence from the D2 transition in trapped cesium atoms, and compare these DOEs to several commercially available refractive micro-lenses. The largest DOE is able to collect over 20% of the atom's radiating sphere whereas the refractive micro-optic is able to collect just 8% of the atom's radiating sphere.

  17. Three-dimensional reconstruction of far and large objects using synthetic aperture integral imaging

    NASA Astrophysics Data System (ADS)

    Piao, Yongri; Xing, Luyan; Zhang, Miao; Lee, Byung-Gook

    2017-01-01

    In this paper, we present a three-dimensional reconstruction of far and large objects in a synthetic aperture integral imaging system. In the proposed method, the far and large size objects are recorded as a set of elemental images by using an additional Plano-concave lens in the synthetic aperture integral imaging system. Due to the use of the Plano-concave lens, the reconstruction distance can be significantly reduced. This enables us to computationally reconstruct the objects in the far-field region. Experimental results are carried out, and the feasibility of the proposed method is verified.

  18. Study on fine annealing process of the large-aperture K9 glasses

    NASA Astrophysics Data System (ADS)

    Gang, Wang; Bin, Liu Yi; Zheng, Li Li; Hui, Zhang; Lei, Xie; Min, Qiu Fu; Ping, Ma; Yao, Yan Ding

    2016-10-01

    Study on fine annealing process of the large-aperture K9 glasses was carried out in the report. The process parameters of glass placed way, fan speed and design of the cavity for keeping temperature uniformity were attained. By the fine annealing experiment, the stress distribution was improved evidently. The stress changed from Irregular distribution to consistency symmetric distribution and the stress max was reduced. The surface profile accuracy of the large-aperture K9 glasses was controlled steadily during CNC polishing.

  19. Passive millimeter wave imaging using a distributed aperture and optical upconversion

    NASA Astrophysics Data System (ADS)

    Dillon, Thomas E.; Schuetz, Christopher A.; Martin, Richard D.; Shi, Shouyuan; Mackrides, Daniel G.; Prather, Dennis W.

    2010-10-01

    We report on our initial results of passive, real-time imaging in the Q-band using a distributed aperture and optical upconversion. The basis of operation is collection of incident mmW radiation by the distributed aperture, as embodied by an array of horn antennas, which is then amplified and upconverted to optical frequencies using commercially available electro-optic modulators. The non-linear mixing of the modulators creates sidebands containing the mmW signal with both amplitude and phase preserved. These signals are relaunched in the optical domain with a homothetic mapping of the antenna array. The optical carrier is stripped via dielectric stack filters and imagery is synthesized from the sidebands using the Fourier transform properties of a simple lens. This imagery is collected using a standard nearinfrared camera with post-processing to enhance the signal of interest and reduce noise. Details of operation and presentation of sample imagery is presented herein.

  20. Split in phase singularities of an optical vortex by off-axis diffraction through a simple circular aperture.

    PubMed

    Taira, Yoshitaka; Zhang, Shukui

    2017-04-01

    Diffraction patterns of an optical vortex through several shaped apertures reveal its topological charge. In this Letter, we theoretically and experimentally show that diffraction of a Laguerre Gaussian beam through a circular aperture at an off-axis position can be used to determine the magnitude and sign of the topological charge. To our knowledge, this is the first time that a simple circular aperture has been used to detect orbital angular momentum of an incident optical vortex.

  1. Split in phase singularities of an optical vortex by off-axis diffraction through a simple circular aperture

    DOE PAGES

    Taira, Yoshitaka; Zhang, Shukui

    2017-03-29

    Here, diffraction patterns of an optical vortex through several shaped apertures reveal its topological charge. In this letter, we theoretically and experimentally show that diffraction of a Laguerre Gaussian beam through a circular aperture at an off-axis position can be used to determine the magnitude and sign of the topological charge. To our knowledge, this is the first time that a simple circular aperture has been used to detect orbital angular momentum of an incident optical vortex.

  2. Large-aperture laser beam scanner for inter-satellite laser communications ground test: assembly and test

    NASA Astrophysics Data System (ADS)

    Sun, Jianfeng; Yang, Lei; Liu, Liren; Shen, Qiande; Xu, Nan

    2006-08-01

    Inter-satellite laser communications attracted more and more attentions due to its excellent performances compared with the RF communications. But the test and verification of the communication terminals are very difficult because of the accuracy and aperture requirement. Large-aperture laser beam scanner was introduced to simulate the relative movement between satellites in the process of ground test for terminals. The scanner includes two same circular wedge prisms, which can scan an arbitrary position in a cone zone. The motivation of the assembly is to guarantee the accuracy of the scanner. Since the large-aperture and high-precision of the scanner, the assembly and test become a very troublesome problem. The test includes: (1) confirm the principal section of the wedge prisms; (2) test the optical quality of the wedge prisms; (3) confirm the scan range of the scanner; (5) test the scan accuracy of the scanner. The test results indicate the assembly process is reasonable. The scan range and accuracy can satisfy the requirement of the ground test of the inter-satellite laser communications terminals.

  3. Propagation equation of Hermite-Gauss beams through a complex optical system with apertures and its application to focal shift.

    PubMed

    Peng, Sun; Jin, Guo; Tingfeng, Wang

    2013-07-01

    Based on the generalized Huygens-Fresnel diffraction integral (Collins' formula), the propagation equation of Hermite-Gauss beams through a complex optical system with a limiting aperture is derived. The elements of the optical system may be all those characterized by an ABCD ray-transfer matrix, as well as any kind of apertures represented by complex transmittance functions. To obtain the analytical expression, we expand the aperture transmittance function into a finite sum of complex Gaussian functions. Thus the limiting aperture is expressed as a superposition of a series of Gaussian-shaped limiting apertures. The advantage of this treatment is that we can treat almost all kinds of apertures in theory. As application, we define the width of the beam and the focal plane using an encircled-energy criterion and calculate the intensity distribution of Hermite-Gauss beams at the actual focus of an aperture lens.

  4. Advances in Mechanical Architectures of Large Precision Space Apertures

    NASA Astrophysics Data System (ADS)

    Datashvili, Leri; Maghaldadze, Nikoloz; Endler, Stephan; Pauw, Julian; He, Peng; Baier, Horst; Ihle, Alexander; Santiago Prowlad, Julian

    2014-06-01

    Recent advances in development of mechanical architectures of large deployable reflectors (LDRs) through the projects of the European Space Agency are addressed in this paper. Two different directions of LDR architectures are being investigated and developed at LSS and LLB. These are LDRs with knitted metal mesh and with flexible shell-membrane reflecting surfaces. The first direction is matured and required advancing of the novel architecture of the supporting structure that provides deployment and final shape accuracy of the metal mesh is underway. The second direction is rather new and its current development stage is focused on investigations of dimensional stability of the flexible shell-membrane reflecting surface. In both directions 5 m diameter functional models will be built to demonstrate achieved performances, which shall prepare the basis for further improvement of their technology readiness levels.

  5. NPT: a large-aperture telescope for high dynamic range astronomy

    NASA Astrophysics Data System (ADS)

    Joseph, Robert D.; Kuhn, Jeff R.; Tokunaga, Alan T.; Coulter, Roy; Ftaclas, Christo; Graves, J. Elon; Hull, Charles L.; Jewitt, D.; Mickey, Donald L.; Moretto, Gilberto; Neill, Doug; Northcott, Malcolm J.; Roddier, Claude A.; Roddier, Francois J.; Siegmund, Walter A.; Owen, Tobias C.

    2000-06-01

    All existing night-time astronomical telescopes, regardless of aperture, are blind to an important part of the universe - the region around bright objects. Technology now exist to build an unobscured 6.5 m aperture telescope which will attain coronagraphic sensitivity heretofore unachieved. A working group hosted by the University of Hawaii Institute for Astronomy has developed plans for a New Planetary Telescope which will permit astronomical observations which have never before ben possible. In its narrow-field mode the off-axis optical design, combined with adaptive optics, provides superb coronagraphic capabilities, and a very low thermal IR background. These make it ideal for studies of extra-solar planets and circumstellar discs, as well as for general IR astronomy. In its wide-field mode the NPT provides a 2 degree diameter field for surveys of Kuiper Belt Objects and Near-Earth Objects, surveys central to current intellectual interests in solar system astronomy.

  6. 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.

  7. Acoustic characterization of high intensity focused ultrasound fields generated from a transmitter with a large aperture

    SciTech Connect

    Chen, Tao; Fan, Tingbo; Zhang, Wei; Qiu, Yuanyuan; Tu, Juan E-mail: dzhang@nju.edu.cn; Guo, Xiasheng; Zhang, Dong E-mail: dzhang@nju.edu.cn

    2014-03-21

    Prediction and measurement of the acoustic field emitted from a high intensity focused ultrasound (HIFU) is essential for the accurate ultrasonic treatment. In this study, the acoustic field generated from a strongly focused HIFU transmitter was characterized by a combined experiment and simulation method. The spheroidal beam equation (SBE) was utilized to describe the nonlinear sound propagation. The curve of the source pressure amplitude versus voltage excitation was determined by fitting the measured ratio of the second harmonic to the fundamental component of the focal waveform to the simulation result; finally, the acoustic pressure field generated by the strongly focused HIFU transmitter was predicted by using the SBE model. A commercial fiber optic probe hydrophone was utilized to measure the acoustic pressure field generated from a 1.1 MHz HIFU transmitter with a large half aperture angle of 30°. The maximum measured peak-to-peak pressure was up to 72 MPa. The validity of this combined approach was confirmed by the comparison between the measured results and the calculated ones. The results indicate that the current approach might be useful to describe the HIFU field. The results also suggest that this method is not valid for low excitations owing to low sensitivity of the second harmonic.

  8. Spectral domain optical coherence tomography with extended depth-of-focus by aperture synthesis

    NASA Astrophysics Data System (ADS)

    Bo, En; Liu, Linbo

    2016-10-01

    We developed a spectral domain optical coherence tomography (SD-OCT) with an extended depth-of-focus (DOF) by synthetizing aperture. For a designated Gaussian-shape light source, the lateral resolution was determined by the numerical aperture (NA) of the objective lens and can be approximately maintained over the confocal parameter, which was defined as twice the Rayleigh range. However, the DOF was proportional to the square of the lateral resolution. Consequently, a trade-off existed between the DOF and lateral resolution, and researchers had to weigh and judge which was more important for their research reasonably. In this study, three distinct optical apertures were obtained by imbedding a circular phase spacer in the sample arm. Due to the optical path difference between three distinct apertures caused by the phase spacer, three images were aligned with equal spacing along z-axis vertically. By correcting the optical path difference (OPD) and defocus-induced wavefront curvature, three images with distinct depths were coherently summed together. This system digitally refocused the sample tissue and obtained a brand new image with higher lateral resolution over the confocal parameter when imaging the polystyrene calibration beads.

  9. Autocorrelation artifacts in optical coherence tomography and interferometric synthetic aperture microscopy.

    PubMed

    Davis, Brynmor J; Ralston, Tyler S; Marks, Daniel L; Boppart, Stephen A; Carney, P Scott

    2007-06-01

    Interferometric synthetic aperture microscopy processing of optical coherence tomography data has been shown to allow computational focusing of en face planes that have traditionally been regarded as out of focus. It is shown that this focusing of the image also produces a defocusing effect in autocorrelation artifacts resulting from Fourier-domain data collection. This effect is verified experimentally and through simulation.

  10. LASER MODES AND BEAMS: Complex-order fractional Fourier transforms in optical schemes with Gaussian apertures

    NASA Astrophysics Data System (ADS)

    Malyutin, A. A.

    2004-10-01

    Several optical schemes performing the complex-order fractional Fourier transform are considered. It is shown that these schemes, containing only Gaussian apertures or their combination with lenses, have eigenbeams represented by Hermite—Gaussian modes with transverse indices m, n<=1 and Laguerre—Gaussian modes with p=0 and l=1. The wave front of the eigenbeams is, as a rule, spherical.

  11. Toward efficient optical trapping of sub-10-nm particles with coaxial plasmonic apertures.

    PubMed

    Saleh, Amr A E; Dionne, Jennifer A

    2012-11-14

    Optical trapping using focused laser beams has emerged as a powerful tool in the biological and physical sciences. However, scaling this technique to nanosized objects remains challenging due to the diffraction limit of light and the high power levels required for nanoscale trapping. In this paper, we propose plasmonic coaxial apertures as low-power optical traps for nanosized specimens. The illumination of a coaxial aperture with a linearly polarized plane wave generates a dual optical trapping potential well. We theoretically show that this potential can stably trap dielectric particles smaller than 10 nm in diameter while keeping the trapping power level below 20 mW. By tapering the thickness of the coaxial dielectric channel, trapping can be extended to sub-2-nm particles. The proposed structures may enable optical trapping and manipulation of dielectric particles ranging from single proteins to small molecules with sizes previously inaccessible.

  12. Fresnel zone plate with apodized aperture for hard X-ray Gaussian beam optics.

    PubMed

    Takeuchi, Akihisa; Uesugi, Kentaro; Suzuki, Yoshio; Itabashi, Seiichi; Oda, Masatoshi

    2017-05-01

    Fresnel zone plates with apodized apertures [apodization FZPs (A-FZPs)] have been developed to realise Gaussian beam optics in the hard X-ray region. The designed zone depth of A-FZPs gradually decreases from the center to peripheral regions. Such a zone structure forms a Gaussian-like smooth-shouldered aperture function which optically behaves as an apodization filter and produces a Gaussian-like focusing spot profile. Optical properties of two types of A-FZP, i.e. a circular type and a one-dimensional type, have been evaluated by using a microbeam knife-edge scan test, and have been carefully compared with those of normal FZP optics. Advantages of using A-FZPs are introduced.

  13. Study on methods for measuring laser energy of large-aperture beam

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Gao, Haoran; Jia, Jing; Hu, Shaoyun; Fan, Hongying

    2014-12-01

    A experimental method measuring laser energy and energy distributing of large-aperture beam is presented. The experimental equipment is established. The energy and energy distribution of beam, the beam size is Φ100mm and Φ360mm, are measured. The result show measuring error for laser energy is less than 8%. The energy distribution is basically consistent.

  14. Algorithms for finely adjusting etch depths to improve the diffraction efficiency uniformity of large-aperture BSG

    NASA Astrophysics Data System (ADS)

    Wu, Lixiang; Qiu, Keqiang; Liu, Ying; Fu, Shaojun

    2015-03-01

    Beam sampling gratings (BSGs) employed in high-power laser systems usually have large aperture so that the adequate uniformity of diffraction efficiency is difficult to obtain. We proposed a deterministic method using controllable non-uniform etch to improve the efficiency uniformity of large-aperture BSGs. During the ion beam etching (IBE) process, etch depths are finely adjusted by the dynamic leaf. The motion trajectory of the dynamic leaf is calculated using the fine adjustment algorithm. Simulations are conducted on the basis of a typical example. The simulation predictions show that the cumulative error is 0.067 nm and about 99.1% of depth differences are in the range of the required etch depth tolerance, which suggests that the diffraction efficiency uniformity of BSG is expected to be effectively improved and thus can meet the requirement of a RMS of 5%. As a cost-effective solution, it also has a broad prospect in many optical fabrication fields, especially for the fabrication of large optics.

  15. A novel method of calculating far-field patterns of large aperture antennas

    NASA Technical Reports Server (NTRS)

    Bailey, M. C.

    1986-01-01

    A method is described for calculation of the radiation pattern of large aperture antennas. A piece-wise linear approximation of the aperture field using overlapping pyramidal basis functions allows the radiation pattern of an aperture antenna to be calculated as though it were a two-dimensional array. The calculation of radiation pattern data versus theta and phi, suitable for 3-D or contour plot algorithms, is achieved by locating the array in the yz-plane and performing a summation over the aperture field data sampled on a square grid. A FORTRAN subroutine is provided for performing radiation pattern calculations. Numerical results are included to demonstrate the accuracy and convergence of the method. These numerical results indicate that typical accuracies of + or - 0.1 dB for Directivity, + or - dB for the 1st Sidelobe Level, and + - 2dB for the 2nd Sidelobe Level can be obtained with an aperture grid of 45x45 points and requires approximately 0.02 seconds CPU time per far-field data point on a VAX 11/750 with a floating point accelerator.

  16. Large optical glass blanks for the ELT generation

    NASA Astrophysics Data System (ADS)

    Jedamzik, Ralf; Petzold, Uwe; Dietrich, Volker; Wittmer, Volker; Rexius, Olga

    2016-07-01

    The upcoming extremely large telescope projects like the E-ELT, TMT or GMT telescopes require not only large amount of mirror blank substrates but have also sophisticated instrument setups. Common instrument components are atmospheric dispersion correctors that compensate for the varying atmospheric path length depending on the telescope inclination angle. These elements consist usually of optical glass blanks that have to be large due to the increased size of the focal beam of the extremely large telescopes. SCHOTT has a long experience in producing and delivering large optical glass blanks for astronomical applications up to 1 m and in homogeneity grades up to H3 quality in the past. The most common optical glass available in large formats is SCHOTT N-BK7. But other glass types like F2 or LLF1 can also be produced in formats up to 1 m. The extremely large telescope projects partly demand atmospheric dispersion components even in sizes beyond 1m up to a range of 1.5 m diameter. The production of such large homogeneous optical glass banks requires tight control of all process steps. To cover this demand in the future SCHOTT initiated a research project to improve the large optical blank production process steps from melting to annealing and measurement. Large optical glass blanks are measured in several sub-apertures that cover the total clear aperture of the application. With SCHOTT's new stitching software it is now possible to combine individual sub-aperture measurements to a total homogeneity map of the blank. In this presentation first results will be demonstrated.

  17. Large Metasurface Aperture for Millimeter Wave Computational Imaging at the Human-Scale

    NASA Astrophysics Data System (ADS)

    Gollub, J. N.; Yurduseven, O.; Trofatter, K. P.; Arnitz, D.; F. Imani, M.; Sleasman, T.; Boyarsky, M.; Rose, A.; Pedross-Engel, A.; Odabasi, H.; Zvolensky, T.; Lipworth, G.; Brady, D.; Marks, D. L.; Reynolds, M. S.; Smith, D. R.

    2017-02-01

    We demonstrate a low-profile holographic imaging system at millimeter wavelengths based on an aperture composed of frequency-diverse metasurfaces. Utilizing measurements of spatially-diverse field patterns, diffraction-limited images of human-sized subjects are reconstructed. The system is driven by a single microwave source swept over a band of frequencies (17.5–26.5 GHz) and switched between a collection of transmit and receive metasurface panels. High fidelity image reconstruction requires a precise model for each field pattern generated by the aperture, as well as the manner in which the field scatters from objects in the scene. This constraint makes scaling of computational imaging systems inherently challenging for electrically large, coherent apertures. To meet the demanding requirements, we introduce computational methods and calibration approaches that enable rapid and accurate imaging performance.

  18. Large Metasurface Aperture for Millimeter Wave Computational Imaging at the Human-Scale.

    PubMed

    Gollub, J N; Yurduseven, O; Trofatter, K P; Arnitz, D; F Imani, M; Sleasman, T; Boyarsky, M; Rose, A; Pedross-Engel, A; Odabasi, H; Zvolensky, T; Lipworth, G; Brady, D; Marks, D L; Reynolds, M S; Smith, D R

    2017-02-20

    We demonstrate a low-profile holographic imaging system at millimeter wavelengths based on an aperture composed of frequency-diverse metasurfaces. Utilizing measurements of spatially-diverse field patterns, diffraction-limited images of human-sized subjects are reconstructed. The system is driven by a single microwave source swept over a band of frequencies (17.5-26.5 GHz) and switched between a collection of transmit and receive metasurface panels. High fidelity image reconstruction requires a precise model for each field pattern generated by the aperture, as well as the manner in which the field scatters from objects in the scene. This constraint makes scaling of computational imaging systems inherently challenging for electrically large, coherent apertures. To meet the demanding requirements, we introduce computational methods and calibration approaches that enable rapid and accurate imaging performance.

  19. Large Metasurface Aperture for Millimeter Wave Computational Imaging at the Human-Scale

    PubMed Central

    Gollub, J. N.; Yurduseven, O.; Trofatter, K. P.; Arnitz, D.; F. Imani, M.; Sleasman, T.; Boyarsky, M.; Rose, A.; Pedross-Engel, A.; Odabasi, H.; Zvolensky, T.; Lipworth, G.; Brady, D.; Marks, D. L.; Reynolds, M. S.; Smith, D. R.

    2017-01-01

    We demonstrate a low-profile holographic imaging system at millimeter wavelengths based on an aperture composed of frequency-diverse metasurfaces. Utilizing measurements of spatially-diverse field patterns, diffraction-limited images of human-sized subjects are reconstructed. The system is driven by a single microwave source swept over a band of frequencies (17.5–26.5 GHz) and switched between a collection of transmit and receive metasurface panels. High fidelity image reconstruction requires a precise model for each field pattern generated by the aperture, as well as the manner in which the field scatters from objects in the scene. This constraint makes scaling of computational imaging systems inherently challenging for electrically large, coherent apertures. To meet the demanding requirements, we introduce computational methods and calibration approaches that enable rapid and accurate imaging performance. PMID:28218254

  20. Tethered Formation Configurations: Meeting the Scientific Objectives of Large Aperture and Interferometric Science

    NASA Technical Reports Server (NTRS)

    Farley, Rodger E.; Quinn, David A.; Brodeur, Stephen J. (Technical Monitor)

    2001-01-01

    With the success of the Hubble Space Telescope, it has become apparent that new frontiers of science and discovery are made every time an improvement in imaging resolution is made. For the HST working primarily in the visible and near-visible spectrum, this meant designing, building, and launching a primary mirror approximately three meters in diameter. Conventional thinking tells us that accomplishing a comparable improvement in resolution at longer wavelengths for Earth and Space Science applications requires a corresponding increase in the size of the primary mirror. For wavelengths in the sub-millimeter range, a very large telescope with an effective aperture in excess of one kilometer in diameter would be needed to obtain high quality angular resolution. Realistically a single aperture this large is practically impossible. Fortunately such large apertures can be constructed synthetically. Possibly as few as three 34 meter diameter mirrors flying in precision formation could be used to collect light at these longer wavelengths permitting not only very large virtual aperture science to be carried out, but high-resolution interferometry as well. To ensure the longest possible mission duration, a system of tethered spacecraft will be needed to mitigate the need for a great deal of propellant. A spin-stabilized, tethered formation will likely meet these requirements. Several configurations have been proposed which possibly meet the needs of the Space Science community. This paper discusses two of them, weighing the relative pros and cons of each concept. The ultimate goal being to settle on a configuration which combines the best features of structure, tethers, and formation flying to meet the ambitious requirements necessary to make future large synthetic aperture and interferometric science missions successful.

  1. Tethered Formation Configurations: Meeting the Scientific Objectives of Large Aperture and Interferometric Science

    NASA Technical Reports Server (NTRS)

    Farley, Rodger E.; Quinn, David A.

    2004-01-01

    With the success of the Hubble Space Telescope, it has become apparent that new frontiers of science and discovery are made every time an improvement in imaging resolution is made. For the HST working primarily in the visible and near-visible spectrum, this meant designing, building and launching a primary mirror approximately three meters in diameter. Conventional thinking tells us that accomplishing a comparable improvement in resolution at longer wavelengths for Earth and Space Science applications requires a corresponding increase in the size of the primary mirror. For wavelengths in the sub-millimeter range, a very large telescope with an effective aperture in excess of one kilometer in diameter would be needed to obtain high quality angular resolution. Realistically a single aperture this large is practically impossible. Fortunately such large apertures can be constructed synthetically. Possibly as few as three 3 - 4 meter diameter mirrors flying in precision formation could be used to collect light at these longer wavelengths permitting not only very large virtual aperture science to be carried out, but high-resolution interferometry as well. To ensure the longest possible mission duration, a system of tethered spacecraft will be needed to mitigate the need for a great deal of propellant. A spin-stabilized, tethered formation will likely meet these requirements. Several configurations have been proposed which possibly meet the needs of the Space Science community. This paper discusses two of them, weighing the relative pros and cons of each concept. The ultimate goal being to settle on a configuration which combines the best features of structure, tethers and formation flying to meet the ambitious requirements necessary to make future large synthetic aperture and interferometric science missions successful.

  2. Multi-spectral modulation detection of co-phasing errors for sparse-optical-synthetic-aperture systems

    NASA Astrophysics Data System (ADS)

    Dong, Li; Peng, Qi; Ma, Haotong; Xie, Zongliang; Wang, Zhipeng

    2016-10-01

    The sparse-optical-synthetic-aperture systems enlarge the aperture and increase the spatial resolution of telescope system via several sub-apertures distributed in specific way. The difficulty of its realization lies in detecting and correcting co-phase errors of the sub-apertures. This paper proposed the method of multi-spectral modulation detection of co-phasing errors for sparse-optical-synthetic-aperture systems. The method can detect the errors via phase modulation on a sub-aperture in the situation of different wavelengths. Firstly, this paper introduced the theory and implementation process of the method in detail. Then the paper analyzed the detection performance of the method and the influence of the sub-apertures structure on detection performance based on a three-sub-aperture system. These results show that the method can accurately detect the sub-apertures' co-phasing errors of the sparse-optical-synthetic-aperture systems. Compared with the current methods, the method proposed in this paper has many advantages, such as faster detection speed and wider detection range.

  3. Large optics inspection, tilting, and washing stand

    SciTech Connect

    Ayers, Marion Jay; Ayers, Shannon Lee

    2012-10-09

    A large optics stand provides a risk free means of safely tilting large optics with ease and a method of safely tilting large optics with ease. The optics are supported in the horizontal position by pads. In the vertical plane the optics are supported by saddles that evenly distribute the optics weight over a large area.

  4. Large optics inspection, tilting, and washing stand

    DOEpatents

    Ayers, Marion Jay [Brentwood, CA; Ayers, Shannon Lee [Brentwood, CA

    2010-08-24

    A large optics stand provides a risk free means of safely tilting large optics with ease and a method of safely tilting large optics with ease. The optics are supported in the horizontal position by pads. In the vertical plane the optics are supported by saddles that evenly distribute the optics weight over a large area.

  5. Measurement of radius of curvature of spherical optical surfaces with small curvature and aperture by optical profiler

    NASA Astrophysics Data System (ADS)

    Ma, Shuang; Yi, Shengzhen; Chen, Shenghao; Wang, Zhanshan

    2014-11-01

    Monochromatic energy multilayer Kirkpatrick-Baez microscope is one of key diagnostic tools for researches on inertial confinement fusion. It is composed by two orthogonal concave spherical mirrors with small curvature and aperture, and produce the image of an object by collecting X-rays in each orthogonal direction, independently. Accurate measurement of radius of curvature of concave spherical mirrors is very important to achieve its design optical properties including imaging quality, optical throughput and energy resolution. However, it is difficult to measure the radius of curvature of spherical optical surfaces with small curvature and aperture by conventional methods, for the produced reflective intensity of glass is too low to correctly test. In this paper, we propose an improved measuring method of optical profiler to accomplish accurate measurement of radius of curvature of spherical optical surfaces with small curvature and aperture used in the monochromatic energy multilayer Kirkpatrick-Baez microscope. Firstly, we use a standard super-smooth optical flat to calibrate reference mirror before each experiment. Following, deviation of central position between measurement area and interference pattern is corrected by the theory of Newton's rings, and the zero-order fringe position is derived from the principle of interference in which surface roughness has minimum values in the position of zero light path difference. Measured results by optical profiler show the low relative errors and high repeatability. Eventually, an imaging experiment of monochromatic energy multilayer Kirkpatrick-Baez microscope determines the measurement accuracy of radius of curvature.

  6. Single exposure optically compressed imaging and visualization using random aperture coding

    NASA Astrophysics Data System (ADS)

    Stern, A.; Rivenson, Yair; Javidi, Bahrain

    2008-11-01

    The common approach in digital imaging follows the sample-then-compress framework. According to this approach, in the first step as many pixels as possible are captured and in the second step the captured image is compressed by digital means. The recently introduced theory of compressed sensing provides the mathematical foundation necessary to combine these two steps in a single one, that is, to compress the information optically before it is recorded. In this paper we overview and extend an optical implementation of compressed sensing theory that we have recently proposed. With this new imaging approach the compression is accomplished inherently in the optical acquisition step. The primary feature of this imaging approach is a randomly encoded aperture realized by means of a random phase screen. The randomly encoded aperture implements random projection of the object field in the image plane. Using a single exposure, a randomly encoded image is captured which can be decoded by proper decoding algorithm.

  7. Two-dimensional synthetic aperture laser optical feedback imaging using galvanometric scanning.

    PubMed

    Witomski, Arnaud; Lacot, Eric; Hugon, Olivier; Jacquin, Olivier

    2008-02-20

    We have improved the resolution of our laser optical feedback imaging (LOFI) setup by using a synthetic aperture (SA) process. We report a two-dimensional (2D) SA LOFI experiment where the unprocessed image (i.e., the classical LOFI image) is obtained point by point, line after line using full 2D galvanometric scanning. The 2D superresolved image is then obtained by successively computing two angular SA operations while a one-dimensional angular synthesis is preceded by a frequency synthesis to obtain a 2D superresolved image conventionally in the synthetic aperture radar (SAR) method and their corresponding laser method called synthetic aperture ladar. The numerical and experimental results are compared.

  8. Computer generated hologram null test of a freeform optical surface with rectangular aperture

    NASA Astrophysics Data System (ADS)

    Su, Ping; Ma, Jianshe; Tan, Qiaofeng; Kang, Guoguo; Liu, Yi; Jin, Guofan

    2012-02-01

    In null computed generated hologram (CGH) test of optical elements, fitting method is needed in null CGH design to generate continuous phase function from the ray-traced discrete phase data. The null CGH for freeform testing usually has a deformed aperture and a high order phase function, because of the aberrations introduced by freeform wavefront propagation. With traditional Zernike polynomial fitting method, selection of an orthogonal basis set and choosing number of terms are needed before fitting. Zernike polynomial fitting method is not suitable in null CGH design for freeform testing; a novel CGH design method with cubic B-spline interpolation is developed. For a freeform surface with 18×18 mm2 rectangular aperture and 630 μm peak-to-valley undulation, the null CGH with a curved rectangular aperture is designed by using the method proposed. Simulation and experimental results proved the feasibility of the novel CGH design method.

  9. Determination of Electron Optical Properties for Aperture Zoom Lenses Using an Artificial Neural Network Method.

    PubMed

    Isik, Nimet

    2016-04-01

    Multi-element electrostatic aperture lens systems are widely used to control electron or charged particle beams in many scientific instruments. By means of applied voltages, these lens systems can be operated for different purposes. In this context, numerous methods have been performed to calculate focal properties of these lenses. In this study, an artificial neural network (ANN) classification method is utilized to determine the focused/unfocused charged particle beam in the image point as a function of lens voltages for multi-element electrostatic aperture lenses. A data set for training and testing of ANN is taken from the SIMION 8.1 simulation program, which is a well known and proven accuracy program in charged particle optics. Mean squared error results of this study indicate that the ANN classification method provides notable performance characteristics for electrostatic aperture zoom lenses.

  10. High numerical aperture large-core photonic crystal fiber for a broadband infrared transmission

    NASA Astrophysics Data System (ADS)

    Pniewski, J.; Stepniewski, G.; Kasztelanic, R.; Siwicki, B.; Pierscinska, D.; Pierscinski, K.; Pysz, D.; Borzycki, K.; Stepien, R.; Bugajski, M.; Buczynski, R.

    2016-11-01

    In this paper we present a large mode area photonic crystal fiber made of the heavy metal oxide glass CS-740, dedicated for a broadband light guidance in the visible, near- and mid-infrared regions of wavelengths from 0.4 to 4.7 μm. The fiber is effectively multi-mode in the considered wavelength range. It is composed of a ring of air-holes surrounding the core, with a high linear filling factor of 0.97. The fiber was made using a standard stack-and-draw technique. Each hole has a size of approx. 2.5 × 3.0 μm and diameter of core is 80 μm. Fiber attenuation is below 3 dB/m in the 0.9-1.7 μm wavelength range, while at 4.4 μm (mid-IR) it is approx. 5 dB/cm. Bending loss at the 1.55 μm wavelength is 0.45 dB per loop of 8 mm radius. Fiber numerical aperture is 0.53 at 1.55 μm. The effective mode area of the fundamental mode is approx. 2400 μm2 in the wavelength range of 0.8-1.7 μm. We present a proof-of-concept demonstration that our large core photonic crystal fiber is able to efficiently collect light directly from a mid-IR quantum cascade laser without use of additional optics and can be used for pigtailing mid-IR sources and detectors.

  11. CAMERA: a compact, automated, laser adaptive optics system for small aperture telescopes

    NASA Astrophysics Data System (ADS)

    Britton, Matthew; Velur, Viswa; Law, Nick; Choi, Philip; Penprase, Bryan E.

    2008-07-01

    CAMERA is an autonomous laser guide star adaptive optics system designed for small aperture telescopes. This system is intended to be mounted permanently on such a telescope to provide large amounts of flexibly scheduled observing time, delivering high angular resolution imagery in the visible and near infrared. The design employs a Shack Hartmann wavefront sensor, a 12x12 actuator MEMS device for high order wavefront compensation, and a solid state 355nm ND:YAG laser to generate a guide star. Commercial CCD and InGaAs detectors provide coverage in the visible and near infrared. CAMERA operates by selecting targets from a queue populated by users and executing these observations autonomously. This robotic system is targeted towards applications that are diffcult to address using classical observing strategies: surveys of very large target lists, recurrently scheduled observations, and rapid response followup of transient objects. This system has been designed and costed, and a lab testbed has been developed to evaluate key components and validate autonomous operations.

  12. Polarization independent high transmission large numerical aperture laser beam focusing and deflection by dielectric Huygens' metasurfaces

    NASA Astrophysics Data System (ADS)

    Özdemir, Aytekin; Hayran, Zeki; Takashima, Yuzuru; Kurt, Hamza

    2017-10-01

    In this letter, we propose all-dielectric Huygens' metasurface structures to construct high numerical aperture flat lenses and beam deflecting devices. The designed metasurface consists of two-dimensional array of all-dielectric nanodisk resonators with spatially varying radii, thereby introducing judiciously designed phase shift to the propagating light. Owing to the overlap of Mie-type magnetic and electric resonances, high transmission was achieved with rigorous design analysis. The designed flat lenses have numerical aperture value of 0.85 and transmission values around 80%. It also offers easy fabrication and compatibility with available semiconductor technology. This spectrally and physically scalable, versatile design could implement efficient wavefront manipulation or beam shaping for high power laser beams, as well as various optical microscopy applications without requiring plasmonic structures that are susceptible to ohmic loss of metals and sensitive to the polarization of light.

  13. Digital Versus Optical Techniques In Synthetic Aperture Radar (SAR) Data Processing

    NASA Astrophysics Data System (ADS)

    Ausherman, Dale A.

    1980-04-01

    The principle of synthetic aperture radar (SAR) image formation is reviewed in preparation for a discussion of both optical and digital processing techniques. The tilted-plane optical processing approach is presented as being representative of optical techniques. Since the newer digital approaches can take several forms, three classes of digital processors are examined: direct convolution, frequency multiplexing, and frequency analysis of dechirped data. A subjective listing of the relative merits for both processing media is presented. Both are found to be technically viable. The final choice will depend primarily upon the application requirements.

  14. Large area damage testing of optics

    SciTech Connect

    Sheehan, L.; Kozlowski, M.; Stolz, C.

    1996-04-26

    The damage threshold specifications for the National Ignition Facility will include a mixture of standard small-area tests and new large-area tests. During our studies of laser damage and conditioning processes of various materials we have found that some damage morphologies are fairly small and this damage does not grow with further illumination. This type of damage might not be detrimental to the laser performance. We should therefore assume that some damage can be allowed on the optics, but decide on a maximum damage allowance of damage. A new specification of damage threshold termed {open_quotes}functional damage threshold{close_quotes} was derived. Further correlation of damage size and type to system performance must be determined in order to use this measurement, but it is clear that it will be a large factor in the optics performance specifications. Large-area tests have verified that small-area testing is not always sufficient when the optic in question has defect-initiated damage. This was evident for example on sputtered polarizer and mirror coatings where the defect density was low enough that the features could be missed by standard small- area testing. For some materials, the scale-length at which damage non-uniformities occur will effect the comparison of small-area and large-area tests. An example of this was the sub-aperture tests on KD*P crystals on the Beamlet test station. The tests verified the large-area damage threshold to be similar to that found when testing a small-area. Implying that for this KD*P material, the dominate damage mechanism is of sufficiently small scale-length that small-area testing is capable of determining the threshold. The Beamlet test station experiments also demonstrated the use of on-line laser conditioning to increase the crystals damage threshold.

  15. The optical synthetic aperture image restoration based on the improved maximum-likelihood algorithm

    NASA Astrophysics Data System (ADS)

    Geng, Zexun; Xu, Qing; Zhang, Baoming; Gong, Zhihui

    2012-09-01

    Optical synthetic aperture imaging (OSAI) can be envisaged in the future for improving the image resolution from high altitude orbits. Several future projects are based on optical synthetic aperture for science or earth observation. Comparing with equivalent monolithic telescopes, however, the partly filled aperture of OSAI induces the attenuation of the modulation transfer function of the system. Consequently, images acquired by OSAI instrument have to be post-processed to restore ones equivalent in resolution to that of a single filled aperture. The maximum-likelihood (ML) algorithm proposed by Benvenuto performed better than traditional Wiener filter did, but it didn't work stably and the point spread function (PSF), was assumed to be known and unchanged in iterative restoration. In fact, the PSF is unknown in most cases, and its estimation was expected to be updated alternatively in optimization. Facing these limitations of this method, an improved ML (IML) reconstruction algorithm was proposed in this paper, which incorporated PSF estimation by means of parameter identification into ML, and updated the PSF successively during iteration. Accordingly, the IML algorithm converged stably and reached better results. Experiment results showed that the proposed algorithm performed much better than ML did in peak signal to noise ratio, mean square error and the average contrast evaluation indexes.

  16. Grid-enhanced X-ray coded aperture microscopy with polycapillary optics

    NASA Astrophysics Data System (ADS)

    Sowa, Katarzyna M.; Last, Arndt; Korecki, Paweł

    2017-03-01

    Polycapillary devices focus X-rays by means of multiple reflections of X-rays in arrays of bent glass capillaries. The size of the focal spot (typically 10-100 μm) limits the resolution of scanning, absorption and phase-contrast X-ray imaging using these devices. At the expense of a moderate resolution, polycapillary elements provide high intensity and are frequently used for X-ray micro-imaging with both synchrotrons and X-ray tubes. Recent studies have shown that the internal microstructure of such an optics can be used as a coded aperture that encodes high-resolution information about objects located inside the focal spot. However, further improvements to this variant of X-ray microscopy will require the challenging fabrication of tailored devices with a well-defined capillary microstructure. Here, we show that submicron coded aperture microscopy can be realized using a periodic grid that is placed at the output surface of a polycapillary optics. Grid-enhanced X-ray coded aperture microscopy with polycapillary optics does not rely on the specific microstructure of the optics but rather takes advantage only of its focusing properties. Hence, submicron X-ray imaging can be realized with standard polycapillary devices and existing set-ups for micro X-ray fluorescence spectroscopy.

  17. Grid-enhanced X-ray coded aperture microscopy with polycapillary optics.

    PubMed

    Sowa, Katarzyna M; Last, Arndt; Korecki, Paweł

    2017-03-21

    Polycapillary devices focus X-rays by means of multiple reflections of X-rays in arrays of bent glass capillaries. The size of the focal spot (typically 10-100 μm) limits the resolution of scanning, absorption and phase-contrast X-ray imaging using these devices. At the expense of a moderate resolution, polycapillary elements provide high intensity and are frequently used for X-ray micro-imaging with both synchrotrons and X-ray tubes. Recent studies have shown that the internal microstructure of such an optics can be used as a coded aperture that encodes high-resolution information about objects located inside the focal spot. However, further improvements to this variant of X-ray microscopy will require the challenging fabrication of tailored devices with a well-defined capillary microstructure. Here, we show that submicron coded aperture microscopy can be realized using a periodic grid that is placed at the output surface of a polycapillary optics. Grid-enhanced X-ray coded aperture microscopy with polycapillary optics does not rely on the specific microstructure of the optics but rather takes advantage only of its focusing properties. Hence, submicron X-ray imaging can be realized with standard polycapillary devices and existing set-ups for micro X-ray fluorescence spectroscopy.

  18. Grid-enhanced X-ray coded aperture microscopy with polycapillary optics

    PubMed Central

    Sowa, Katarzyna M.; Last, Arndt; Korecki, Paweł

    2017-01-01

    Polycapillary devices focus X-rays by means of multiple reflections of X-rays in arrays of bent glass capillaries. The size of the focal spot (typically 10–100 μm) limits the resolution of scanning, absorption and phase-contrast X-ray imaging using these devices. At the expense of a moderate resolution, polycapillary elements provide high intensity and are frequently used for X-ray micro-imaging with both synchrotrons and X-ray tubes. Recent studies have shown that the internal microstructure of such an optics can be used as a coded aperture that encodes high-resolution information about objects located inside the focal spot. However, further improvements to this variant of X-ray microscopy will require the challenging fabrication of tailored devices with a well-defined capillary microstructure. Here, we show that submicron coded aperture microscopy can be realized using a periodic grid that is placed at the output surface of a polycapillary optics. Grid-enhanced X-ray coded aperture microscopy with polycapillary optics does not rely on the specific microstructure of the optics but rather takes advantage only of its focusing properties. Hence, submicron X-ray imaging can be realized with standard polycapillary devices and existing set-ups for micro X-ray fluorescence spectroscopy. PMID:28322316

  19. Measurement of the optical fiber numeric aperture exposed to thermal and radiation aging

    NASA Astrophysics Data System (ADS)

    Vanderka, Ales; Bednarek, Lukas; Hajek, Lukas; Latal, Jan; Poboril, Radek; Zavodny, Petr; Vasinek, Vladimir

    2016-12-01

    This paper deals with the aging of optical fibers influenced by temperature and radiation. There are analyzed changes in the structure of the optical fiber, related to the propagation of light in the fiber structure. In this case for numerical aperture. For experimental measurement was used MM fiber OM1 with core diameter 62.5 μm, cladding diameter 125 μm in 2.8 mm secondary coating. Aging of the optical fiber was achieved with dry heat and radiation. For this purpose, we were using a temperature chamber with a stable temperature of 105 °C where the cables after two months. Cables were then irradiated with gamma radiation 60Co in doses of 1.5 kGy and then 60 kGy. These conditions simulated 50 years aging process of optical cables. According to European Standard EN 60793-1-43:2015 was created the automatic device for angular scan working with LabVIEW software interface. Numerical aperture was tested at a wavelength of 850 nm, with an output power 1 mW. Scanning angle was set to 50° with step 0.25°. Numerical aperture was calculated from the position where power has fallen from maximal power at e2 power. The measurement of each sample was performed 10 hours after thermal and radiation aging. The samples were subsequently tested after six months from the last irradiation. In conclusion, the results of the experiment were analyzed and compared.

  20. Optical Property Enhancement and Durability Evaluation of Heat Receiver Aperture Shield Materials

    NASA Technical Reports Server (NTRS)

    deGroh, Kim K.; Jaworske, Donald A.; Smith, Daniela C.

    1998-01-01

    Under the Solar Dynamic Flight Demonstration (SDFD) program, NASA Lewis Research Center worked with AlliedSignal Aerospace, the heat receiver contractor, on the development, characterization and durability testing of refractory metals to obtain appropriate optical and thermal properties for the SDFD heat receiver aperture shield. Molybdenum and tungsten foils were grit-blasted using silicon carbide or alumina grit under various grit-blasting conditions for optical property enhancement. Black rhenium coated tungsten foil was also evaluated. Tungsten, black rhenium-coated tungsten, and grit-blasted tungsten screens of various mesh sizes were placed over the pristine and grit-blasted foils for optical property characterization. Grit-blasting was found to be effective in decreasing the specular reflectance and the absorptance/emittance ratio of the refractory foils. The placement of a screen further enhanced these optical properties, with a grit-blasted screen over a grit-blasted foil producing the best results. Based on the optical property enhancement results, samples were tested for atomic oxygen and vacuum heat treatment durability. Grit-blasted (Al2O3 grit) 2 mil tungsten foil was chosen for the exterior layer of the SDFD heat receiver aperture shield. A 0.007 in. wire diameter, 20 x 20 mesh tungsten screen was chosen to cover the tungsten foil. Based on these test results, a heat receiver aperture shield test unit has been built with the screen covered grit-blast tungsten foil exterior layers. The aperture shield was tested and verified the thermal and structural durability of the outer foil layers during an off-pointing period.

  1. Performance of a multiple-aperture optical system

    NASA Astrophysics Data System (ADS)

    Belmonte, Aniceto M.; Comeron, Adolfo; Bara, Javier; Rubio, Juan A.; Fernandez, Estela; Menendez-Valdes, Pedro

    1996-04-01

    Atmospheric turbulence causes intensity and phase disturbances on the wavefront of electromagnetic waves propagation through it that can seriously degrade the reliability of free- space optical communication links. This paper deals with the estimation of the statistics for power fades resulting from the combined effects of distortion of the receiving system instantaneous point-spread function and from the fluctuations of the collected power arising from wavefront intensity fluctuations. Fractal techniques are employed to simulate the turbulence-induced point-spread function distortions, while a log-normal model is assumed for the collected-power fluctuations. The reduction in the cumulative probability of losses due to these two effects through spatial diversity using a multiaperture receiver configuration is assessed.

  2. Novel optical super-resolution pattern with upright edges diffracted by a tiny thin aperture.

    PubMed

    Wu, Jiu Hui; Zhou, Kejiang

    2015-08-24

    In the past decade numerous efforts have been concentrated to achieve optical imaging resolution beyond the diffraction limit. In this letter a thin microcavity theory of near-field optics is proposed by using the power flow theorem firstly. According to this theory, the near-field optical diffraction from a tiny aperture whose diameter is less than one-tenth incident wavelength embedded in a thin conducting film is investigated by considering this tiny aperture as a thin nanocavity. It is very surprising that there exists a kind of novel super-resolution diffraction patterns showing resolution better than λ/80 (λ is the incident wavelength), which is revealed for the first time to our knowledge in this letter. The mechanism that has allowed the imaging with this kind of super-resolution patterns is due to the interaction between the incident wave and the thin nanocavity with a complex wavenumber. More precisely, these super-resolution patterns with discontinuous upright peaks are formed by one or three items of the integration series about the cylindrical waves according to our simulation results. This novel optical super-resolution with upright edges by using the thin microcavity theory presented in the study could have potential applications in the future semiconductor lithography process, nano-size laser-drilling technology, microscopy, optical storage, optical switch, and optical information processing.

  3. Single-molecule detection at high concentrations with optical aperture nanoantennas

    NASA Astrophysics Data System (ADS)

    Alam, Md Shah; Karim, Farzia; Zhao, Chenglong

    2016-05-01

    Single-molecule detection has become an indispensable technology in life science, and medical research. In order to get meaningful information on many biological processes, single-molecule analysis is required in micro-molar concentrations. At such high concentrations, it is very challenging to isolate a single molecule with conventional diffraction-limited optics. Recently, optical aperture nanoantennas (OANs) have emerged as a powerful tool to enhance the single-molecule detection under a physiological environment. The OANs, which consist of nano-scale apertures on a metallic film, have the following unique properties: (1) nanoscale light confinement; (2) enhanced fluorescence emission; (3) tunable radiation pattern; (4) reduced background noise; and (5) massive parallel detection. This review presents the fundamentals, recent developments and future perspectives in this emerging field.

  4. A Large-Aperture Acoustic Array to Observe Oceanic Density Structure

    DTIC Science & Technology

    1975-12-01

    Subtitle) ._,,, , , : A ^ARGE-APERTURb ^ COUSTIC ARRAY TO ^OBSERVE OCEANIC DENSITY STRUCTURE t 7. AUTHORfj; G. Thomas/Kaye READ INSTRUCTIONS...o CO (M MARINE PHYSICAL LABORATORY of the Scripps Institution of Oceanography San Diego, California 92132 A LARGE APERTURE ACOUSTIC ARRAY TO...Contracts Contract Effective Date: Contract Expiration Date; Amount of Contract: Layered Inhomogeneities N00014-69- A -0200-6038 \\ 1 April 1972 Jiß

  5. Mechanical analysis and measurement of wheel-rail contact system in large aperture radio telescope

    NASA Astrophysics Data System (ADS)

    Chen, Z. P.; Kong, D. Q.; Li, C. G.; Zhu, N. J.; Shi, H. L.

    2016-07-01

    The azimuth rotation part of a large aperture radio telescope usually takes one wheel-rail system; therefore, wheel-rail pointing errors and wheel-rail wear are very important to antenna point accuracy. First, this paper discusses the wheelrail contact theory and some specific characteristics of wheel-rail system in large aperture radio telescope. Second, one 3D model of wheel-rail contact system is built according to the parameters of 50m antenna in China, and the model is analyzed by one whole body in MSC.Patran/Nastran. Third, we use the multi-body dynamic method to build the model of wheel-rail and simulate it in RecurDyn software. Comparing the simulation results, we find that the coupling of rigidbody and soft-body is much more precise than one whole body in describing the contact deformation. And the results also explain the crevice's influence on the mechanical properties of wheel-rail contact system. Finally, some experiments and measurements of 50m antenna are made, by which we get some useful tips for large aperture radio telescope. The test results show that the multi-body dynamic method is much more suitable to the mechanical analysis in wheel-rail contact system.

  6. A Large Aperture Fabry-Perot Tunable Filter Based On Micro Opto Electromechanical Systems Technology

    NASA Technical Reports Server (NTRS)

    Greenhouse, Matt; Mott, Brent; Powell, Dan; Barclay, Rich; Hsieh, Wen-Ting

    2002-01-01

    A research and development effort sponsored by the NASA Goddard Spaceflight Center (GSFC) is focused on applying Micro Opto Electromechanical Systems (MOEMS) technology to create a miniature Fabry-Perot tunable etalon for space and ground-based near infrared imaging spectrometer applications. Unlike previous devices developed for small-aperture telecommunications systems, the GSFC research is directed toward a novel 12 - 40 mm aperture for astrophysical studies, including emission line imaging of galaxies and nebulae, and multi-spectral redshift surveys in the 1.1 - 2.3 micron wavelength region. The MOEMS design features integrated electrostatic scanning of the 11-micron optical gap, and capacitance micrometry for closed loop control of parallelism within a 10-nm tolerance. The low thermal mass and inertia inherent in MOEMS devices allows for rapid cooling to the proposed 30 K operating temperature, and high frequency response. Achieving the proposed 6-nm aperture flatness (with an effective finesse of 50) represents the primary technical challenge in the current 12-mm prototype.

  7. A Large Aperture Fabry-Perot Tunable Filter Based On Micro Opto Electromechanical Systems Technology

    NASA Technical Reports Server (NTRS)

    Greenhouse, Matt; Mott, Brent; Powell, Dan; Barclay, Rich; Hsieh, Wen-Ting

    2002-01-01

    A research and development effort sponsored by the NASA Goddard Spaceflight Center (GSFC) is focused on applying Micro Opto Electromechanical Systems (MOEMS) technology to create a miniature Fabry-Perot tunable etalon for space and ground-based near infrared imaging spectrometer applications. Unlike previous devices developed for small-aperture telecommunications systems, the GSFC research is directed toward a novel 12 - 40 mm aperture for astrophysical studies, including emission line imaging of galaxies and nebulae, and multi-spectral redshift surveys in the 1.1 - 2.3 micron wavelength region. The MOEMS design features integrated electrostatic scanning of the 11-micron optical gap, and capacitance micrometry for closed loop control of parallelism within a 10-nm tolerance. The low thermal mass and inertia inherent in MOEMS devices allows for rapid cooling to the proposed 30 K operating temperature, and high frequency response. Achieving the proposed 6-nm aperture flatness (with an effective finesse of 50) represents the primary technical challenge in the current 12-mm prototype.

  8. Optical image reconstruction using an astigmatic lens for synthetic-aperture imaging ladar

    NASA Astrophysics Data System (ADS)

    Sun, Zhiwei; Hou, Peipei; Zhi, Yanan; Sun, Jianfeng; Zhou, Yu; Xu, Qian; Liu, Liren

    2014-11-01

    An optical processor for synthetic-aperture imaging ladar (SAIL) utilizing one astigmatic lens is proposed. The processor comprises two structures of transmitting and reflecting. The imaging process is mathematically analyzed using the unified data-collection equation of side-looking and down-looking SAILs. Results show that the astigmatic lens can be replaced with a cylindrical lens on certain conditions. To verify this concept, laboratory experiment is conducted, the imaging result of data collected from one SAIL demonstrator is given.

  9. An Engineering Design Reference Mission for a Future Large-Aperture UVOIR Space Observatory

    NASA Astrophysics Data System (ADS)

    Thronson, Harley A.; Bolcar, Matthew R.; Clampin, Mark; Crooke, Julie A.; Redding, David; Rioux, Norman; Stahl, H. Philip

    2016-01-01

    From the 2010 NRC Decadal Survey and the NASA Thirty-Year Roadmap, Enduring Quests, Daring Visions, to the recent AURA report, From Cosmic Birth to Living Earths, multiple community assessments have recommended development of a large-aperture UVOIR space observatory capable of achieving a broad range of compelling scientific goals. Of these priority science goals, the most technically challenging is the search for spectroscopic biomarkers in the atmospheres of exoplanets in the solar neighborhood. Here we present an engineering design reference mission (EDRM) for the Advanced Technology Large-Aperture Space Telescope (ATLAST), which was conceived from the start as capable of breakthrough science paired with an emphasis on cost control and cost effectiveness. An EDRM allows the engineering design trade space to be explored in depth to determine what are the most demanding requirements and where there are opportunities for margin against requirements. Our joint NASA GSFC/JPL/MSFC/STScI study team has used community-provided science goals to derive mission needs, requirements, and candidate mission architectures for a future large-aperture, non-cryogenic UVOIR space observatory. The ATLAST observatory is designed to operate at a Sun-Earth L2 orbit, which provides a stable thermal environment and excellent field of regard. Our reference designs have emphasized a serviceable 36-segment 9.2 m aperture telescope that stows within a five-meter diameter launch vehicle fairing. As part of our cost-management effort, this particular reference mission builds upon the engineering design for JWST. Moreover, it is scalable to a variety of launch vehicle fairings. Performance needs developed under the study are traceable to a variety of additional reference designs, including options for a monolithic primary mirror.

  10. Dual-band co-aperture infrared optical system design for irradiance measurement

    NASA Astrophysics Data System (ADS)

    Mu, Da; Mi, Shilong; Mu, Meng

    2014-11-01

    Irradiance is a basic parameter in radiation measurement and play a big role in the research of radiation source.Since infrared target simulator is difficult to precisely calibrate itself and the irradiance value of standard blackbody is infinitely small,besides,some other objective environment factors like dust,dirty spot,vapour,especially the temperature lay worse effect on common infrared system,so it's crucial to decrease energy deficiency and various aberrations throughout integrated elements of optical system to increase measurement precision. Therefore,in this paper, a relatively precise imaging system is designed to measure the irradiance of the simulator itself--the dual-band co-aperture infrared optical system,it can work well under bad conditions said above,particularly when the target isn't fill up with the FOV(field of view). Generally infrared optical system needs big clear aperture, as for the objective of this system,an improved Cassegrain optical system as the co-aperture can be used to receive middle-wave infrared(MWIR3~5μm) and long-wave infrared(LWIR8~12μm) from standard blackbody radiation.As we all know that Cassegrain system has a satisfying relatively bigger aperture and reflective system has no chromatic aberration problem, a proper obstruction ratio of second lens and a hole in the centre of primary lens of the original system must be changed reasonably .So the radiation with least energy deficiency and aberration can be received successfully now. The two beams depart from the hole of primary lens separated by a coated (reflect MWIR and transmit LWIR film or vice versa) beam splitter, then the two different wavelength waves can be divided into two different optical path and finally received by MWIR and LWIR detectors respectively.The design result shows that the distortions of system are both small and the curves of modulation transfer function (MTF) approach the diffraction limit simultaneously in MWIR( 3~5μm) and LWIR( 8~12

  11. 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.

  12. The Last Gasps of VY Canis Majoris: Aperture Synthesis and Adaptive Optics Imagery

    NASA Astrophysics Data System (ADS)

    Monnier, J. D.; Tuthill, P. G.; Lopez, B.; Cruzalebes, P.; Danchi, W. C.; Haniff, C. A.

    1999-02-01

    We present new observations of the red supergiant VY CMa at 1.25, 1.65, 2.26, 3.08, and 4.8 μm. Two complementary observational techniques were utilized: nonredundant aperture masking on the 10 m Keck I telescope, yielding images of the innermost regions at unprecedented resolution, and adaptive optics imaging on the ESO 3.6 m telescope at La Silla, attaining an extremely high (~105) peak-to-noise dynamic range over a wide field. For the first time the inner dust shell has been resolved in the near-infrared to reveal a one-sided extension of circumstellar emission within 0.1" (~15 R*) of the star. The line-of-sight optical depths of the circumstellar dust shell at 1.65, 2.26, and 3.08 μm have been estimated to be 1.86+/-0.42, 0.85+/-0.20, and 0.44+/-0.11, respectively. These new results allow the bolometric luminosity of VY CMa to be estimated independent of the dust shell geometry, yielding L*~2×105 Lsolar. A variety of dust condensations, including a large scattering plume and a bow-shaped dust feature, were observed in the faint, extended nebula up to 4" from the central source. While the origin of the nebulous plume remains uncertain, a geometrical model is developed assuming the plume is produced by radially driven dust grains forming at a rotating flow insertion point with a rotational period between 1200 and 4200 yr, which is perhaps the stellar rotational period or the orbital period of an unseen companion.

  13. Dual FOV infrared lens design with the laser common aperture optics

    NASA Astrophysics Data System (ADS)

    Chang, Wei-jun; Zhang, Xuan-zhi; Luan, Ya-dong; Zhang, Bo

    2015-02-01

    With the demand of autonomous precision guidance of air defense missile, the system scheme of the IR imaging/Ladar dual-mode seeker with a common aperture was proposed, and the optical system used in was designed. The system had a common receiving aperture, and its structure was very compact, so it could meet the requirement for the miniaturization of the seeker. Besides, it also could meet the demands of a wide field of view for searching target, and the demands for accurately recognizing and tracking the target at the same time. In order to increase the narrow FOV tracking performance, the dual FOV infrared optical used the zooming mode which some components flip in or out the optical system to firm the target signal. The dual FOV optics are divided into the zooming part, with dual variable focal length, and the reimaging part which was chosen in such a way to minimize the objective lens while maintaining 100% cold shield efficiency. The final infrared optics including 4°×3°(NFOV) and 16°×12°(WFOV) was designed. The NFOV lens composed of two common IR/Ladar lens, three relay lens, a beam splitter and two reflective fold mirrors, while WFOV lens increased two lens such as Germanium and Silicon. The common IR/Ladar lens ZnS and ZnSe could refractive the IR optics and Laser optics. The beam splitter which refractived IR optics and reflected Laser optics was located in the middle of Germanium and Silicon. The designed optical system had good image quality, and fulfilled the performance requirement of seeker system.

  14. Large-aperture laser differential confocal ultra-long focal length measurement and its system.

    PubMed

    Zhao, Weiqian; Li, Zhigang; Qiu, Lirong; Ren, Huan; Shao, Rongjun

    2015-06-29

    A new laser differential confocal ultra-long focal length measurement (LDCFM) method is proposed with the capability to self-calibrate the reference lens (RL) focal length and the axial space between the test lens and RL. Using the property that the focus of laser differential confocal ultra-long focal length measurement system (LDCFS) precisely corresponds to the null point of the differential confocal axial intensity curve, the proposed LDCFM measures the RL focal length f(R)' by precisely identifying the positions of the focus and last surface of RL, measures the axial space d(0) between RL and test ultra-long focal length lens (UFL) by identifying the last surface of RL and the vertex of UFL last surface, and measures the variation l in focus position of LDCFS with and without test UFL, and then calculates the UFL focal length f(T)' by the above measured f(R)', d(0) and l. In addition, a LDCFS based on the proposed method is developed for a large aperture lens. The experimental results indicate that the relative uncertainty is less than 0.01% for the test UFL, which has an aperture of 610 mm and focal length of 31,000 mm. LDCFM provides a novel approach for the high-precision focal-length measurement of large-aperture UFL.

  15. Source-Search Sensitivity of a Large-Area, Coded-Aperture, Gamma-Ray Imager

    SciTech Connect

    Ziock, K P; Collins, J W; Craig, W W; Fabris, L; Lanza, R C; Gallagher, S; Horn, B P; Madden, N W; Smith, E; Woodring, M L

    2004-10-27

    We have recently completed a large-area, coded-aperture, gamma-ray imager for use in searching for radiation sources. The instrument was constructed to verify that weak point sources can be detected at considerable distances if one uses imaging to overcome fluctuations in the natural background. The instrument uses a rank-19, one-dimensional coded aperture to cast shadow patterns onto a 0.57 m{sup 2} NaI(Tl) detector composed of 57 individual cubes each 10 cm on a side. These are arranged in a 19 x 3 array. The mask is composed of four-centimeter thick, one-meter high, 10-cm wide lead blocks. The instrument is mounted in the back of a small truck from which images are obtained as one drives through a region. Results of first measurements obtained with the system are presented.

  16. Aperture scaling effects with monolithic periodically poled lithium niobate optical parametric oscillators and generators.

    PubMed

    Missey, M; Dominic, V; Powers, P; Schepler, K L

    2000-02-15

    We used elliptical beams to demonstrate aperture scaling effects in nanosecond single-grating and multigrating periodically poled lithium niobate (PPLN) monolithic optical parametric oscillators and generators. Increasing the cavity Fresnel number in single-grating crystals broadened both the beam divergence and the spectral bandwidth. Both effects are explained in terms of the phase-matching geometry. These effects are suppressed when a multigrating PPLN crystal is used because the individual gratings provide small effective subapertures. A flood-pumped multigrating optical parametric generator displayed a low output beam divergence and contained 19 pairs of signal and idler frequencies.

  17. Three-dimensional speckle size in generalized optical systems with limiting apertures.

    PubMed

    Ward, Jennifer E; Kelly, Damien P; Sheridan, John T

    2009-08-01

    Correlation properties of speckle fields at the output of quadratic phase systems with hard square and circular apertures are examined. Using the linear canonical transform and ABCD ray matrix techniques to describe these general optical systems, we first derive analytical formulas for determining axial and lateral speckle sizes. Then using a numerical technique, we extend the analysis so that the correlation properties of nonaxial speckles can also be considered. Using some simple optical systems as examples, we demonstrate how this approach may be conveniently applied. The results of this analysis apply broadly both to the design of metrology systems and to speckle control schemes.

  18. Quasi-optical grids with thin rectangular patch/aperture elements

    NASA Technical Reports Server (NTRS)

    Wu, Te-Kao

    1993-01-01

    Theoretical analysis is presented for an efficient and accurate performance evaluation of quasi-optical grids comprised of thin rectangular patch/aperture elements with/without a dielectric substrate/superstrate. The convergence rate of this efficient technique is improved by an order of magnitude with the approximate edge conditions incorporated in the basis functions of the integral equation solution. Also presented are the interesting applications of this efficient analytical technique to the design and performance evaluation of the coupling grids and beam splitters in the optical systems as well as thermal protection sunshields used in the communication systems of satellites and spacecrafts.

  19. Detection of and compensation for blocked elements using large coherent apertures: ex vivo studies

    NASA Astrophysics Data System (ADS)

    Jakovljevic, Marko; Bottenus, Nick; Kuo, Lily; Kumar, Shalki; Dahl, Jeremy; Trahey, Gregg

    2016-04-01

    When imaging with ultrasound through the chest wall, it is not uncommon for parts of the array to get blocked by ribs, which can limit the acoustic window and significantly impede visualization of the structures of interest. With the development of large-aperture, high-element-count, 2-D arrays and their potential use in transthoracic imaging, detecting and compensating for the blocked elements is becoming increasingly important. We synthesized large coherent 2-D apertures and used them to image a point target through excised samples of canine chest wall. Blocked elements are detected based on low amplitude of their signals. As a part of compensation, blocked elements are turned off on transmit (Tx) and receive (Rx), and point-target images are created using: coherent summation of the remaining channels, compounding of intercostal apertures, and adaptive weighting of the available Tx/Rx channel-pairs to recover the desired k-space response. The adaptive compensation method also includes a phase aberration correction to ensure that the non-blocked Tx/Rx channel pairs are summed coherently. To evaluate the methods, we compare the point-spread functions (PSFs) and near-field clutter levels for the transcostal and control acquisitions. Specifically, applying k-space compensation to the sparse aperture data created from the control acquisition reduces sidelobes from -6.6 dB to -12 dB. When applied to the transcostal data in combination with phase-aberration correction, the same method reduces sidelobes only by 3 dB, likely due to significant tissue induced acoustic noise. For the transcostal acquisition, turning off blocked elements and applying uniform weighting results in maximum clutter reduction of 5 dB on average, while the PSF stays intact. Compounding reduces clutter by about 3 dB while the k-space compensation increases clutter magnitude to the non-compensated levels.

  20. Non-overlap subaperture interferometric testing for large optics

    NASA Astrophysics Data System (ADS)

    Wu, Xin; Yu, Yingjie; Zeng, Wenhan; Qi, Te; Chen, Mingyi; Jiang, Xiangqian

    2017-08-01

    It has been shown that the number of subapertures and the amount of overlap has a significant influence on the stitching accuracy. In this paper, a non-overlap subaperture interferometric testing method (NOSAI) is proposed to inspect large optical components. This method would greatly reduce the number of subapertures and the influence of environmental interference while maintaining the accuracy of reconstruction. A general subaperture distribution pattern of NOSAI is also proposed for the large rectangle surface. The square Zernike polynomial is employed to fit such wavefront. The effect of the minimum fitting terms on the accuracy of NOSAI and the sensitivities of NOSAI to subaperture's alignment error, power systematic error, and random noise are discussed. Experimental results validate the feasibility and accuracy of the proposed NOSAI in comparison with wavefront obtained by a large aperture interferometer and stitching surface by multi-aperture overlap-scanning technique (MAOST).

  1. The design of common aperture and multi-band optical system based on day light telescope

    NASA Astrophysics Data System (ADS)

    Chen, Jiao; Wang, Ling; Zhang, Bo; Teng, Guoqi; Wang, Meng

    2017-02-01

    As the development of electro-optical weapon system, the technique of common path and multi-sensor are used popular, and becoming a trend. According to the requirement of miniaturization and lightweight for electro-optical stabilized sighting system, a day light telescope/television viewing-aim system/ laser ranger has been designed in this thesis, which has common aperture. Thus integration scheme of multi-band and common aperture has been adopted. A day light telescope has been presented, which magnification is 8, field of view is 6°, and distance of exit pupil is more than 20mm. For 1/3" CCD, television viewing-aim system which has 156mm focal length, has been completed. In addition, laser ranging system has been designed, with 10km raging distance. This paper outlines its principle which used day light telescope as optical reference of correcting the optical axis. Besides, by means of shared objective, reserved image with inverting prism and coating beam-splitting film on the inclined plane of the cube prism, the system has been applied to electro-optical weapon system, with high-resolution of imaging and high-precision ranging.

  2. Propagation of partially coherent twisted anisotropic Gaussian Schell-model beams through an apertured astigmatic optical system.

    PubMed

    Cai, Yangjian; Hu, Li

    2006-03-15

    By expanding the hard-aperture function into a finite sum of complex Gaussian functions, we derived an approximate analytical formula for a partially coherent twisted anisotropic Gaussian Schell-model (AGSM) beam propagating through an apertured paraxial general astigmatic (GA) optical system by use of a tensor method. The results obtained by using the approximate analytical formula are in good agreement with those obtained by using the numerical integral calculation. Our formulas avoid time-consuming numerical integration and provide a convenient and effective way for studying the propagation and transformation of a partially coherent twisted AGSM beam through an apertured paraxial GA optical system.

  3. Optical bistability based on nonlinear oblique reflection of light beams from a screen with an aperture on its axis

    SciTech Connect

    Nikitenko, K Yu; Trofimov, V A

    1999-02-28

    It is shown that, in principle, optical bistability can be based on a nonlinear interaction of noncollinearly propagating beams when one of them is reflected from a plane screen with an aperture on its axis. The requirements to be satisfied by the interacting beams are discussed and estimates are obtained of the shortest response time of such an optically bistable system. (nonlinear optical phenomena)

  4. MRF Applications: On the Road to Making Large-Aperture Ultraviolet Laser Resistant Continuous Phase Plates for High-Power Lasers

    SciTech Connect

    Menapace, J A; Davis, P J; Steele, W A; Hachkowski, M R; Nelson, A; Xin, K

    2006-10-26

    Over the past two years we have developed MRF tools and procedures to manufacture large-aperture (430 X 430 mm) continuous phase plates (CPPs) that are capable of operating in the infrared portion (1053 nm) of high-power laser systems. This is accomplished by polishing prescribed patterns of continuously varying topographical features onto finished plano optics using MRF imprinting techniques. We have been successful in making, testing, and using large-aperture CPPs whose topography possesses spatial periods as low as 4 mm and surface peak-to-valleys as high as 8.6 {micro}m. Combining this application of MRF technology with advanced MRF finishing techniques that focus on ultraviolet laser damage resistance makes it potentially feasible to manufacture large-aperture CPPs that can operate in the ultraviolet (351 nm) without sustaining laser-induced damage. In this paper, we will discuss the CPP manufacturing process and the results of 351-nm/3-nsec equivalent laser performance experiments conducted on large-aperture CPPs manufactured using advanced MRF protocols.

  5. Deployable large aperture optics system for remote sensing applications.

    SciTech Connect

    Sumali, Anton Hartono; Martin, Jeffrey W.; Main, John A.; Macke, Benjamin T.; Massad, Jordan Elias; Chaplya, Pavel Mikhail

    2004-04-01

    This report summarizes research into effects of electron gun control on piezoelectric polyvinylidene fluoride (PVDF) structures. The experimental apparatus specific to the electron gun control of this structure is detailed, and the equipment developed for the remote examination of the bimorph surface profile is outlined. Experiments conducted to determine the optimum electron beam characteristics for control are summarized. Clearer boundaries on the bimorphs control output capabilities were determined, as was the closed loop response. Further controllability analysis of the bimorph is outlined, and the results are examined. In this research, the bimorph response was tested through a matrix of control inputs of varying current, frequency, and amplitude. Experiments also studied the response to electron gun actuation of piezoelectric bimorph thin film covered with multiple spatial regions of control. Parameter ranges that yielded predictable control under certain circumstances were determined. Research has shown that electron gun control can be used to make macrocontrol and nanocontrol adjustments for PVDF structures. The control response and hysteresis are more linear for a small range of energy levels. Current levels needed for optimum control are established, and the generalized controllability of a PVDF bimorph structure is shown.

  6. Future Large-Aperture Ultraviolet/Optical/Infrared Space Observatory

    NASA Technical Reports Server (NTRS)

    Thronson, Harley; Mandell, Avi; Polidan, Ron; Tumlinson, Jason

    2016-01-01

    Since the beginning of modern astronomical science in the early 1900s, astronomers have yearned to escape the turbulence and absorption of Earth's atmosphere by placing observatories in space. One of the first papers to lay out the advantages of space astronomy was by Lyman Spitzer in 1946, "Astronomical Advantages of an Extra-Terrestrial Observatory," though later in life he minimized the influence of this work. Since that time, and especially gaining momentum in the 1960s after the launch of Sputnik, astronomers, technologists, and engineers continued to advance, organizing scientific conferences, advocating for necessary technologies, and assessing sophisticated designs for increasingly ambitious space observations at ultraviolet, visual, and infrared (UVOIR) wavelengths. These community-wide endeavors, combined with the explosion in technological capability enabled by the Apollo era, led to rapid advancement in space observatory performance that culminated in the spectacularly successful Hubble Space Telescope (HST), launched in 1990 and still returning surpassing scientific results.

  7. An optical technology study on large aperture telescopes

    NASA Technical Reports Server (NTRS)

    Korsch, D.

    1985-01-01

    The difficult and crucial problem of selecting a suitable telescope concept for an advanced space observatory was examined. To this end two and four mirror telescopes were analyzed and compared. Both configurations are very practical and structurally similar. Parabolic primary and spherical primary four mirror telescope were compared with respect to their performance and the alignment sensitivities of the three correction mirrors. A 1 meter class afocal telescope system with lag angle compensation, to be used in a LIDAR experiment, was examined.

  8. High resolution beamforming on large aperture vertical line arrays: Processing synthetic data

    NASA Astrophysics Data System (ADS)

    Tran, Jean-Marie Q.; Hodgkiss, William S.

    1990-09-01

    This technical memorandum studies the beamforming of large aperture line arrays deployed vertically in the water column. The work concentrates on the use of high resolution techniques. Two processing strategies are envisioned: (1) full aperture coherent processing which offers in theory the best processing gain; and (2) subaperture processing which consists in extracting subapertures from the array and recombining the angular spectra estimated from these subarrays. The conventional beamformer, the minimum variance distortionless response (MVDR) processor, the multiple signal classification (MUSIC) algorithm and the minimum norm method are used in this study. To validate the various processing techniques, the ATLAS normal mode program is used to generate synthetic data which constitute a realistic signals environment. A deep-water, range-independent sound velocity profile environment, characteristic of the North-East Pacific, is being studied for two different 128 sensor arrays: a very long one cut for 30 Hz and operating at 20 Hz; and a shorter one cut for 107 Hz and operating at 100 Hz. The simulated sound source is 5 m deep. The full aperture and subaperture processing are being implemented with curved and plane wavefront replica vectors. The beamforming results are examined and compared to the ray-theory results produced by the generic sonar model.

  9. LUPUS I observations from the 2010 flight of the Balloon-borne large aperture submillimeter telescope for polarimetry

    SciTech Connect

    Matthews, Tristan G.; Chapman, Nicholas L.; Novak, Giles; Ade, Peter A. R.; Hargrave, Peter C.; Nutter, David; Angilè, Francesco E.; Devlin, Mark J.; Klein, Jeffrey; Benton, Steven J.; Fissel, Laura M.; Gandilo, Natalie N.; Netterfield, Calvin B.; Chapin, Edward L.; Fukui, Yasuo; Gundersen, Joshua O.; Korotkov, Andrei L.; Moncelsi, Lorenzo; Mroczkowski, Tony K.; Olmi, Luca; and others

    2014-04-01

    The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) was created by adding polarimetric capability to the BLAST experiment that was flown in 2003, 2005, and 2006. BLASTPol inherited BLAST's 1.8 m primary and its Herschel/SPIRE heritage focal plane that allows simultaneous observation at 250, 350, and 500 μm. We flew BLASTPol in 2010 and again in 2012. Both were long duration Antarctic flights. Here we present polarimetry of the nearby filamentary dark cloud Lupus I obtained during the 2010 flight. Despite limitations imposed by the effects of a damaged optical component, we were able to clearly detect submillimeter polarization on degree scales. We compare the resulting BLASTPol magnetic field map with a similar map made via optical polarimetry. (The optical data were published in 1998 by J. Rizzo and collaborators.) The two maps partially overlap and are reasonably consistent with one another. We compare these magnetic field maps to the orientations of filaments in Lupus I, and we find that the dominant filament in the cloud is approximately perpendicular to the large-scale field, while secondary filaments appear to run parallel to the magnetic fields in their vicinities. This is similar to what is observed in Serpens South via near-IR polarimetry, and consistent with what is seen in MHD simulations by F. Nakamura and Z. Li.

  10. Lupus I Observations from the 2010 Flight of the Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry

    NASA Astrophysics Data System (ADS)

    Matthews, Tristan G.; Ade, Peter A. R.; Angilè, Francesco E.; Benton, Steven J.; Chapin, Edward L.; Chapman, Nicholas L.; Devlin, Mark J.; Fissel, Laura M.; Fukui, Yasuo; Gandilo, Natalie N.; Gundersen, Joshua O.; Hargrave, Peter C.; Klein, Jeffrey; Korotkov, Andrei L.; Moncelsi, Lorenzo; Mroczkowski, Tony K.; Netterfield, Calvin B.; Novak, Giles; Nutter, David; Olmi, Luca; Pascale, Enzo; Poidevin, Frédérick; Savini, Giorgio; Scott, Douglas; Shariff, Jamil A.; Soler, Juan Diego; Tachihara, Kengo; Thomas, Nicholas E.; Truch, Matthew D. P.; Tucker, Carole E.; Tucker, Gregory S.; Ward-Thompson, Derek

    2014-04-01

    The Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) was created by adding polarimetric capability to the BLAST experiment that was flown in 2003, 2005, and 2006. BLASTPol inherited BLAST's 1.8 m primary and its Herschel/SPIRE heritage focal plane that allows simultaneous observation at 250, 350, and 500 μm. We flew BLASTPol in 2010 and again in 2012. Both were long duration Antarctic flights. Here we present polarimetry of the nearby filamentary dark cloud Lupus I obtained during the 2010 flight. Despite limitations imposed by the effects of a damaged optical component, we were able to clearly detect submillimeter polarization on degree scales. We compare the resulting BLASTPol magnetic field map with a similar map made via optical polarimetry. (The optical data were published in 1998 by J. Rizzo and collaborators.) The two maps partially overlap and are reasonably consistent with one another. We compare these magnetic field maps to the orientations of filaments in Lupus I, and we find that the dominant filament in the cloud is approximately perpendicular to the large-scale field, while secondary filaments appear to run parallel to the magnetic fields in their vicinities. This is similar to what is observed in Serpens South via near-IR polarimetry, and consistent with what is seen in MHD simulations by F. Nakamura and Z. Li.

  11. Mg-doped congruent LiTaO3 crystal for large-aperture quasi-phase matching device.

    PubMed

    Ishizuki, Hideki; Taira, Takunori

    2008-10-13

    Mg-doped congruent composition LiTaO(3) (MgLT) crystal, which can be grown by a conventional Czochralski method, has improved properties such as transparent range, thermal conductivity, and coercive field compared to conventional undoped congruent LiTaO(3). In this paper, various properties of MgLT including Mg-doping dependence are characterized, and also compared to that of undoped congruent LiTaO(3), LiNbO(3), and Mg-doped congruent LiNbO(3), as a material of high power quasi-phase matching (QPM) device. Up to 3-mm-thick periodically poled MgLT crystal is shown to demonstrate the possibility of large-aperture QPM-MgLT devices. Subsequently, optical parametric oscillation experiments by using periodically poled MgLT are demonstrated to discuss an efficient QPM condition.

  12. A cryogenic rotation stage with a large clear aperture for the half-wave plates in the Spider instrument.

    PubMed

    Bryan, Sean; Ade, Peter; Amiri, Mandana; Benton, Steven; Bihary, Richard; Bock, James; Bond, J Richard; Chiang, H Cynthia; Contaldi, Carlo; Crill, Brendan; Dore, Olivier; Elder, Benjamin; Filippini, Jeffrey; Fraisse, Aurelien; Gambrel, Anne; Gandilo, Natalie; Gudmundsson, Jon; Hasselfield, Matthew; Halpern, Mark; Hilton, Gene; Holmes, Warren; Hristov, Viktor; Irwin, Kent; Jones, William; Kermish, Zigmund; Lawrie, Craig; MacTavish, Carrie; Mason, Peter; Megerian, Krikor; Moncelsi, Lorenzo; Montroy, Thomas; Morford, Tracy; Nagy, Johanna; Netterfield, C Barth; Padilla, Ivan; Rahlin, Alexandra S; Reintsema, Carl; Riley, Daniel C; Ruhl, John; Runyan, Marcus; Saliwanchik, Benjamin; Shariff, Jamil; Soler, Juan; Trangsrud, Amy; Tucker, Carole; Tucker, Rebecca; Turner, Anthony; Wen, Shyang; Wiebe, Donald; Young, Edward

    2016-01-01

    We describe the cryogenic half-wave plate rotation mechanisms built for and used in Spider, a polarization-sensitive balloon-borne telescope array that observed the cosmic microwave background at 95 GHz and 150 GHz during a stratospheric balloon flight from Antarctica in January 2015. The mechanisms operate at liquid helium temperature in flight. A three-point contact design keeps the mechanical bearings relatively small but allows for a large (305 mm) diameter clear aperture. A worm gear driven by a cryogenic stepper motor allows for precise positioning and prevents undesired rotation when the motors are depowered. A custom-built optical encoder system monitors the bearing angle to an absolute accuracy of ±0.1(∘). The system performed well in Spider during its successful 16 day flight.

  13. A cryogenic rotation stage with a large clear aperture for the half-wave plates in the Spider instrument

    NASA Astrophysics Data System (ADS)

    Bryan, Sean; Ade, Peter; Amiri, Mandana; Benton, Steven; Bihary, Richard; Bock, James; Bond, J. Richard; Chiang, H. Cynthia; Contaldi, Carlo; Crill, Brendan; Dore, Olivier; Elder, Benjamin; Filippini, Jeffrey; Fraisse, Aurelien; Gambrel, Anne; Gandilo, Natalie; Gudmundsson, Jon; Hasselfield, Matthew; Halpern, Mark; Hilton, Gene; Holmes, Warren; Hristov, Viktor; Irwin, Kent; Jones, William; Kermish, Zigmund; Lawrie, Craig; MacTavish, Carrie; Mason, Peter; Megerian, Krikor; Moncelsi, Lorenzo; Montroy, Thomas; Morford, Tracy; Nagy, Johanna; Netterfield, C. Barth; Padilla, Ivan; Rahlin, Alexandra S.; Reintsema, Carl; Riley, Daniel C.; Ruhl, John; Runyan, Marcus; Saliwanchik, Benjamin; Shariff, Jamil; Soler, Juan; Trangsrud, Amy; Tucker, Carole; Tucker, Rebecca; Turner, Anthony; Wen, Shyang; Wiebe, Donald; Young, Edward

    2016-01-01

    We describe the cryogenic half-wave plate rotation mechanisms built for and used in Spider, a polarization-sensitive balloon-borne telescope array that observed the cosmic microwave background at 95 GHz and 150 GHz during a stratospheric balloon flight from Antarctica in January 2015. The mechanisms operate at liquid helium temperature in flight. A three-point contact design keeps the mechanical bearings relatively small but allows for a large (305 mm) diameter clear aperture. A worm gear driven by a cryogenic stepper motor allows for precise positioning and prevents undesired rotation when the motors are depowered. A custom-built optical encoder system monitors the bearing angle to an absolute accuracy of ±0.1∘. The system performed well in Spider during its successful 16 day flight.

  14. Note: Computer controlled rotation mount for large diameter optics

    NASA Astrophysics Data System (ADS)

    Rakonjac, Ana; Roberts, Kris O.; Deb, Amita B.; Kjærgaard, Niels

    2013-02-01

    We describe the construction of a motorized optical rotation mount with a 40 mm clear aperture. The device is used to remotely control the power of large diameter laser beams for a magneto-optical trap. A piezo-electric ultrasonic motor on a printed circuit board provides rotation with a precision better than 0.03° and allows for a very compact design. The rotation unit is controlled from a computer via serial communication, making integration into most software control platforms straightforward.

  15. Nonlinear techniques in optical synthetic aperture radar image generation and target recognition.

    PubMed

    Weaver, S; Wagner, K

    1995-07-10

    One of the most successful optical signal-processing applications to date has been the use of optical processors to convert synthetic aperture radar (SAR) data into images of the radar reflectivity of the ground. We have demonstrated real-time input to a high-space-bandwidth optical SAR imagegeneration system by using a dynamic organic holographic recording medium and SAR phase-history data. Real-time speckle reduction in optically processed SAR imagery has been accomplished by the use of multilook averaging to achieve nonlinear modulus-squared accumulation of subaperture images. We designed and assembled an all-optical system that accomplished real-time target recognition in SAR imagery. This system employed a simple square-law nonlinearity in the form of an optically addressed spatial light modulator at the SAR image plane to remove the effects of speckle phase profiles returned from complex SAR targets. The detection stage enabled the creation of an optical SAR automatic target recognition system as a nonlinear cascade of an optical SAR image generator and an optical correlator.

  16. Servomechanism for Doppler shift compensation in optical correlator for synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Constaninides, N. J.; Bicknell, T. J. (Inventor)

    1980-01-01

    A method and apparatus for correcting Doppler shifts in synthetic aperture radar data is described. An optical correlator for synthetic aperture radar data has a means for directing a laser beam at a signal film having radar return pulse intensity information recorded on it. A resultant laser beam passes through a range telescope, an azimuth telescope, and a Fourier transform filter located between the range and azimuth telescopes, and forms an image for recording on an image film. A compensation means for Doppler shift in the radar return pulse intensity information includes a beam splitter for reflecting the modulated laser beam, after having passed through the Fourier transform filter, to a detection screen having two photodiodes mounted on it.

  17. Large Coded Aperture Mask for Spaceflight Hard X-ray Images

    NASA Technical Reports Server (NTRS)

    Vigneau, Danielle N.; Robinson, David W.

    2002-01-01

    The 2.6 square meter coded aperture mask is a vital part of the Burst Alert Telescope on the Swift mission. A random, but known pattern of more than 50,000 lead tiles, each 5 mm square, was bonded to a large honeycomb panel which projects a shadow on the detector array during a gamma ray burst. A two-year development process was necessary to explore ideas, apply techniques, and finalize procedures to meet the strict requirements for the coded aperture mask. Challenges included finding a honeycomb substrate with minimal gamma ray attenuation, selecting an adhesive with adequate bond strength to hold the tiles in place but soft enough to allow the tiles to expand and contract without distorting the panel under large temperature gradients, and eliminating excess adhesive from all untiled areas. The largest challenge was to find an efficient way to bond the > 50,000 lead tiles to the panel with positional tolerances measured in microns. In order to generate the desired bondline, adhesive was applied and allowed to cure to each tile. The pre-cured tiles were located in a tool to maintain positional accuracy, wet adhesive was applied to the panel, and it was lowered to the tile surface with synchronized actuators. Using this procedure, the entire tile pattern was transferred to the large honeycomb panel in a single bond. The pressure for the bond was achieved by enclosing the entire system in a vacuum bag. Thermal vacuum and acoustic tests validated this approach. This paper discusses the methods, materials, and techniques used to fabricate this very large and unique coded aperture mask for the Swift mission.

  18. A fundamental mode Nd:GdVO4 laser pumped by a large aperture 808 nm VCSEL

    NASA Astrophysics Data System (ADS)

    Hao, Y. Q.; Ma, J. L.; Yan, C. L.; Liu, G. J.; Ma, X. H.; Gong, J. F.; Feng, Y.; Wei, Z. P.; Wang, Y. X.; Zhao, Y. J.

    2013-05-01

    A fundamental mode Nd:GdVO4 laser pumped by a vertical cavity surface emitting laser (VCSEL) is experimentally demonstrated. The VCSEL has a circular output-beam which makes it easier for it to be directly coupled to a Nd:GdVO4 microcrystal. In our research, a large aperture 808 nm VCSEL, with a multi-ring-shaped aperture (MRSA) and an almost Gaussian-shaped far-field profile, is used as the pumping source. Experimental results for the Nd:GdVO4 laser pumped by the VCSEL are presented. The maximum output peak power of 0.754 W is obtained under a pump peak power of 1.3 W, and the corresponding opto-optic conversion efficiency is 58.1%. The average slope efficiency is 65.8% from the threshold pump power of 0.2 W to the pump power of 1.3 W. The laser beam quality factors are measured to be {M}x2=1.2 0 and {M}y2=1.1 5.

  19. Simulation of image formation in x-ray coded aperture microscopy with polycapillary optics.

    PubMed

    Korecki, P; Roszczynialski, T P; Sowa, K M

    2015-04-06

    In x-ray coded aperture microscopy with polycapillary optics (XCAMPO), the microstructure of focusing polycapillary optics is used as a coded aperture and enables depth-resolved x-ray imaging at a resolution better than the focal spot dimensions. Improvements in the resolution and development of 3D encoding procedures require a simulation model that can predict the outcome of XCAMPO experiments. In this work we introduce a model of image formation in XCAMPO which enables calculation of XCAMPO datasets for arbitrary positions of the object relative to the focal plane as well as to incorporate optics imperfections. In the model, the exit surface of the optics is treated as a micro-structured x-ray source that illuminates a periodic object. This makes it possible to express the intensity of XCAMPO images as a convolution series and to perform simulations by means of fast Fourier transforms. For non-periodic objects, the model can be applied by enforcing artificial periodicity and setting the spatial period larger then the field-of-view. Simulations are verified by comparison with experimental data.

  20. Focal aberrations of large-aperture HOPG von-Hàmos x-ray spectrometers

    NASA Astrophysics Data System (ADS)

    Zastrau, U.; Brown, C. R. D.; Döppner, T.; Glenzer, S. H.; Gregori, G.; Lee, H. J.; Marschner, H.; Toleikis, S.; Wehrhan, O.; Förster, E.

    2012-09-01

    Focal aberrations of large-aperture highly oriented pyrolytic graphite (HOPG) crystals in von-Hàmos geometry are investigated by experimental and computational methods. A mosaic HOPG crystal film of 100 μm thickness diffracts 8 keV x-rays. This thickness is smaller than the absorption depth of the symmetric 004-reflection, which amounts to 257 μm. Cylindrically bent crystals with 110mm radius of curvature and up to 100 mm collection width produce a X-shaped halo around the focus. This feature vanishes when the collection aperture is reduced, but axial spectral profiles show that the resolution is not affected. X-ray topography reveals significant inhomogeneous crystallite domains of 2±1mm diameter along the entire crystal. Rocking curves shift by about ±20arcmin between domains, while their full width at half-maximum varies between 30 and 50 arcmin. These inhomogeneities are not imprinted at the focal spot, since the monochromatically reflecting area of the crystal is large compared to inhomogeneities. Ray-tracing calculations using a Monte-Carlo-based algorithm developed for mosaic crystals reproduce the X-shaped halo in the focal plane, stemming from the mosaic defocussing in the non-dispersive direction in combination with large apertures. The best achievable resolution is found by analyzing a diversity of rocking curve widths, source sizes and crystal thicknesses for 8 keV x-rays to be ΔE/E ~ 10-4. Finally a general analytic expression for the shape of the aberration is derived.

  1. Overview of Mirror Technology Development for Large Lightweight Space-Based Optical Systems

    NASA Technical Reports Server (NTRS)

    Smith, W. Scott; Stahl, H. P.; Rose, M. Frank (Technical Monitor)

    2000-01-01

    The Space Optics Manufacturing Technology Center of Marshall Space Flight Center is involved in the development of lightweight optics for spacebased'systems. The NGST and other future NASA programs require large aperture space-based instruments. This paper reviews the technologies under development for NGST including discussions of the environmental testing of candidate segment for the NGST primary mirror.

  2. Spacecraft Conceptual Design for the 8-Meter Advanced Technology Large Aperture Space Telescope (ATLAST)

    NASA Technical Reports Server (NTRS)

    Hopkins, Randall C.; Capizzo, Peter; Fincher, Sharon; Hornsby, Linda S.; Jones, David

    2010-01-01

    The Advanced Concepts Office at Marshall Space Flight Center completed a brief spacecraft design study for the 8-meter monolithic Advanced Technology Large Aperture Space Telescope (ATLAST-8m). This spacecraft concept provides all power, communication, telemetry, avionics, guidance and control, and thermal control for the observatory, and inserts the observatory into a halo orbit about the second Sun-Earth Lagrange point. The multidisciplinary design team created a simple spacecraft design that enables component and science instrument servicing, employs articulating solar panels for help with momentum management, and provides precise pointing control while at the same time fast slewing for the observatory.

  3. Development of an efficient large-aperture high damage-threshold sol-gel diffraction grating.

    SciTech Connect

    Ashley, Carol S.; Rambo, Patrick K.; Schwarz, Jens; Dunphy, Darren Robert; Branson, Eric D.; Smith, Ian Craig; Johnson, William Arthur; Reed, Scott T.; Cook, Adam W.

    2005-03-01

    In order to develop the next generation of high peak intensity lasers, new grating technology providing higher damage thresholds and large apertures is required. The current assumption is that this technical innovation will be multilayer dielectric gratings, wherein the uppermost layer of a thin film mirror is etched to create the desired binary phase grating. A variant of this is explored with the upper grating layer being a lower density gelatin-based volume phase grating in either sol-gel or dichromated gelatin. One key benefit is the elimination of the etching step.

  4. 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.

  5. Optically controlled dense current structures driven by relativistic plasma aperture-induced diffraction

    NASA Astrophysics Data System (ADS)

    Gonzalez-Izquierdo, Bruno; Gray, Ross J.; King, Martin; Dance, Rachel J.; Wilson, Robbie; McCreadie, John; Butler, Nicholas M. H.; Capdessus, Remi; Hawkes, Steve; Green, James S.; Borghesi, Marco; Neely, David; McKenna, Paul

    2016-05-01

    The collective response of charged particles to intense fields is intrinsic to plasma accelerators and radiation sources, relativistic optics and many astrophysical phenomena. Here we show that a relativistic plasma aperture is generated in thin foils by intense laser light, resulting in the fundamental optical process of diffraction. The plasma electrons collectively respond to the resulting laser near-field diffraction pattern, producing a beam of energetic electrons with a spatial structure that can be controlled by variation of the laser pulse parameters. It is shown that static electron-beam and induced-magnetic-field structures can be made to rotate at fixed or variable angular frequencies depending on the degree of ellipticity in the laser polarization. The concept is demonstrated numerically and verified experimentally, and is an important step towards optical control of charged particle dynamics in laser-driven dense plasma sources.

  6. All-reflective optical target illumination system with high numerical aperture

    DOEpatents

    Thomas, Carlton E.; Sigler, Robert D.; Hoeger, John G.

    1979-01-01

    An all-reflective optical system for providing illumination of a target focal region at high numerical aperture from a pair of confluent collimated light beams. The collimated beams are each incident upon an associated concave eccentric pupil paraboloidal reflective surface, and thereby each focused through an opening in an associated outer ellipsoidal reflective surface onto a plane reflector. Each beam is reflected by its associated plane reflector onto the opposing concave surface of the outer ellipsoids to be focused through an opening in the plane surface onto an opposing inner concave ellipsoidal reflective surface, and thence onto the target region.

  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. Optical design through optimization for rectangular apertures using freeform orthogonal polynomials: a case study

    NASA Astrophysics Data System (ADS)

    Nikolic, Milena; Benítez, Pablo; Narasimhan, Bharathwaj; Grabovickic, Dejan; Liu, Jayao; Miñano, Juan C.

    2016-07-01

    Several applications of freeform optics call for deeper analysis of systems with rectangular apertures. We study the behavior of a freeform mirror system by comparing four orthogonal polynomial surface representations through local optimization. We compare polynomials with different orthogonal areas (rectangular-circular) and different metrics (sag-gradient). Polynomials orthogonal inside a rectangle converge faster or to a better local minimum than those orthogonal inside a circle in the example considered. This is the most likely due to the loss of the good properties of orthogonality when the orthogonality area does not coincide with the surface area used.

  9. A conceptual design of a large aperture microwave radiometer geostationary platform

    NASA Technical Reports Server (NTRS)

    Garn, Paul A.; Garrison, James L.; Jasinski, Rachel

    1992-01-01

    A conceptual design of a Large Aperture Microwave Radiometer (LAMR) Platform has been developed and technology areas essential to the design and on-orbit viability of the platform have been defined. Those technologies that must be developed to the requirement stated here for the LAMR mission to be viable include: advanced radiation resistant solar cells, integrated complex structures, large segmented reflector panels, sub 3 kg/m(exp 2) areal density large antennas, and electric propulsion systems. Technology areas that require further development to enhance the capabilities of the LAMR platform (but are not essential for viability) include: electrical power storage, on-orbit assembly, and on-orbit systems checkout and correction.

  10. Repetitively pulsed regime of Nd : glass large-aperture laser amplifiers

    SciTech Connect

    Kuzmin, A A; Khazanov, Efim A; Shaykin, A A

    2012-04-30

    A repetitively pulsed operation regime of neodymium glass rod laser amplifiers with apertures of 4.5, 6, 8.5, and 10 cm is analysed using experimental data. The limits of an increase in the pulse repetition rates are determined. Universal dependences are obtained, which help finding a compromise between increasing the repetition rate and enhancing the gain for each particular case. In particular, it is shown that an amplifier 4.5-cm in diameter exhibits a five-fold safety factor with respect to a thermo-mechanical breakdown at a repetition rate of 1 pulse min{sup -1} and stored energy of above 100 J. A strong thermally induced birefringence in two such amplifiers is experimentally reduced to a 'cold' level by employing a 90 Degree-Sign optical rotator.

  11. Acoustic characterization of high intensity focused ultrasound field generated from a transmitter with large aperture

    NASA Astrophysics Data System (ADS)

    Fan, Tingbo; Chen, Tao; Zhang, Wei; Hu, Jimin; Zhang, Yichuan; Zhang, Dong

    2017-03-01

    A combined experiment and simulation method was utilized to characterize the acoustic field generated from a strong focused HIFU transmitter. The nonlinear sound propagation was described by the spheroidal beam equation (SBE). The relationship between the source pressure amplitude and excitation voltage was determined by fitting the measured ratio of the second harmonic to the fundamental component of the focal waveform to the simulation result; then the acoustic pressure field generated by the strong focused transducer was predicted by using the SBE model. A commercial fiber optic probe hydrophone (FOPH) was utilized to measure the acoustic pressure field generated from a 1.1 MHz HIFU transmitter with a half aperture angle of 30°. The validity of this combined approach was confirmed by the comparison between the measured results and the calculated ones. The results show that the current approach might be useful to describe the HIFU field.

  12. Aperture averaging and correlation function measurements in strong atmospheric turbulence for optical wireless applications

    NASA Astrophysics Data System (ADS)

    Yuksel, Heba; Harris, Joseph; Tang, Yunxin; Gammon, Robert; Davis, Christopher

    2008-08-01

    The performance of free space optical (FSO) links in a clear atmosphere is affected by the non-ideal characteristics of the communication channel. Atmospheric turbulence causes fluctuations in the received signal level, which increase the bit errors in a digital communication link. In order to quantify performance limitations, a better understanding of the effect of the intensity fluctuations on the received signal at all turbulence levels is needed. Theory reliably describes the behavior in the weak turbulence regime, but theoretical descriptions in the intermediate and strong turbulence regimes are less well developed. We have developed a flexible empirical approach for characterizing link performance in strong turbulence conditions through image analysis of intensity scintillation patterns coupled with frame aperture averaging on an FSO communication link. These measurements are complemented with direct measurements of temporal and spatial correlation functions. A He-Ne laser beam propagates 106 meters in free-space over flat terrain about a meter above the ground to provide strong atmospheric turbulence conditions. A high performance digital camera with a frame-grabbing computer interface is used to capture received laser intensity distributions at rates up to 30 frames per second and various short shutter speeds, down to 1/16,000s per frame. A scintillometer is used for accurate measurements of the turbulence parameter Cn2. Laboratory measurements use a local strong turbulence generator, which mimics a strong phase screen. Spatial correlation functions are measured using laterally separated point detectors placed in the receiver plane. Correlations and captured image frames are analyzed in Labview to evaluate correlation functions, Cn2, and the aperture averaging factor. The aperture averaging results demonstrate the expected reduction in intensity fluctuations with increasing aperture diameter, and show quantitatively the differences in behavior between

  13. Optical layouts for large infrared beamline opening angles

    NASA Astrophysics Data System (ADS)

    Moreno, Th; Westfahl, H.; de Oliveira Freitas, R.; Petroff, Y.; Dumas, P.

    2013-03-01

    The number of infrared beamlines at synchrotron facilities is expending worldwide. Due to the long wavelength of the radiation in the infrared region, the optimum collection of the emitted photons requires large opening angles, both vertically and horizontally (order of few tens of mrad). Most of the infrared beamlines use toroid shaped mirrors, or elliptical mirror to conjointly focus both the vertical and the horizontal source emission. However, such optical set ups produce distorted images due to the optical aberrations produced by the depth and the circular shape of the source. In this article, we propose a new optical layout consisting in two optimized shape mirrors, focusing independently the vertical and the horizontal source emission, and providing low aberration beams for large horizontal apertures. The setup has been used to design the new LNLS Brazilian synchrotron Infrared beamline.

  14. Recent developments in wafer-level fabrication of micro-optical multi-aperture imaging systems

    NASA Astrophysics Data System (ADS)

    Leitel, R.; Dannberg, P.; Brückner, A.; Bräuer, A.

    2011-10-01

    Micro-optical systems, that utilize multiple channels for imaging instead of a single one, are frequently discussed for ultra-compact applications such as digital cameras. The strategy of their fabrication differs due to different concepts of image formation. Illustrated by recently implemented systems for multi-aperture imaging, typical steps of wafer-level fabrication are discussed in detail. In turn, the made progress may allow for additional degrees of freedom in optical design. Pressing ahead with very short overall lengths and multiple diaphragm array layers, results in the use of extremely thin glass substrates down to 100 microns in thickness. The desire for a wide field of view for imaging has led to chirped arrays of microlenses and diaphragms. Focusing on imaging quality, aberrations were corrected by introducing toroidal lenslets and elliptical apertures. Such lenslets had been generated by thermal reflow of lithographic patterned photoresist and subsequent molding. Where useful, the system's performance can be further increased by applying aspheric microlenses from reactive ion etching (RIE) transfer or by achromatic doublets from superimposing two moldings with different polymers. Multiple diaphragm arrays prevent channel crosstalk. But using simple metal layers may lead to multiple reflections and an increased appearance of ghost images. A way out are low reflecting black matrix polymers that can be directly patterned by lithography. But in case of environmental stability and high resolution, organic coatings should be replaced by patterned metal coatings that exhibit matched antireflective layers like the prominent black chromium. The mentioned components give an insight into the fabrication process of multi-aperture imaging systems. Finally, the competence in each step decides on the overall image quality.

  15. Diffractive imaging analysis of large-aperture segmented telescope based on partial Fourier transform

    NASA Astrophysics Data System (ADS)

    Dong, Bing; Qin, Shun; Hu, Xinqi

    2013-09-01

    Large-aperture segmented primary mirror will be widely used in next-generation space-based and ground-based telescopes. The effects of intersegment gaps, obstructions, position and figure errors of segments, which are all involved in the pupil plane, on the image quality metric should be analyzed using diffractive imaging theory. Traditional Fast Fourier Transform (FFT) method is very time-consuming and costs a lot of memory especially in dealing with large pupil-sampling matrix. A Partial Fourier Transform (PFT) method is first proposed to substantially speed up the computation and reduce memory usage for diffractive imaging analysis. Diffraction effects of a 6-meter segmented mirror including 18 hexagonal segments are simulated and analyzed using PFT method. The influence of intersegment gaps and position errors of segments on Strehl ratio is quantitatively analyzed by computing the Point Spread Function (PSF). By comparing simulation results with theoretical results, the correctness and feasibility of PFT method is confirmed.

  16. Nonlinear optical characterization of graphite oxide thin film by open aperture Z-scan technique

    SciTech Connect

    Sreeja, V. G.; Reshmi, R.; Devasia, Sebin; Anila, E. I.; Cheruvalathu, Ajina

    2016-05-23

    In this paper we explore the structural characterization of graphite oxide powder prepared from graphite powder by oxidation via modified Hummers method. The nonlinear optical properties of the spin coated graphite oxide thin film is also explored by open aperture Z-Scan technique. Structural and physiochemical properties of the samples were investigated with the help of Fourier Transform Infrared Spectroscopy (FTIR) and Raman Spectroscopy (Raman).The results of FT-IR and Raman spectroscopy showed that the graphite is oxidized by strong oxidants and the oxygen atoms are introduced into the graphite layers forming C=C, O-H and –C-H groups. The synthesized sample has good crystalline nature with lesser defects. The nonlinear optical property of GO thin film was studied by open aperture Z-Scan technique using Q-switched Nd-Yag Laser at 532 nm. The Z-scan plot showed that the investigated GO thin film has saturable absorption behavior. The nonlinear absorption coefficient and saturation intensity were also estimated to explore its applications in Q switched mode locking laser systems.

  17. Combining freeform optics and curved detectors for wide field imaging: a polynomial approach over squared aperture.

    PubMed

    Muslimov, Eduard; Hugot, Emmanuel; Jahn, Wilfried; Vives, Sebastien; Ferrari, Marc; Chambion, Bertrand; Henry, David; Gaschet, Christophe

    2017-06-26

    In the recent years a significant progress was achieved in the field of design and fabrication of optical systems based on freeform optical surfaces. They provide a possibility to build fast, wide-angle and high-resolution systems, which are very compact and free of obscuration. However, the field of freeform surfaces design techniques still remains underexplored. In the present paper we use the mathematical apparatus of orthogonal polynomials defined over a square aperture, which was developed before for the tasks of wavefront reconstruction, to describe shape of a mirror surface. Two cases, namely Legendre polynomials and generalization of the Zernike polynomials on a square, are considered. The potential advantages of these polynomials sets are demonstrated on example of a three-mirror unobscured telescope with F/# = 2.5 and FoV = 7.2x7.2°. In addition, we discuss possibility of use of curved detectors in such a design.

  18. Fabrication of Efficient, Large Aperture Transmission Diffraction Gratings by Ion-Beam Etching

    SciTech Connect

    Nguyen, H T; Bryan, S R; Britten, J A; Perry, M D

    2000-09-14

    The utilization of high-power short pulse laser employing chirped-pulse amplification (CPA) for material processing and inertial confinement research is widely increasing. The performance of these high-power CPA laser system continues to be limited by the ability of the pulse compression gratings to hold up to the high-average-power or high-peak-power of the laser. Pulse compression gratings used in transmission and fabricated out of bulk fused silica have intrinsically the highest laser damage threshold when compared with metal or multilayer dielectric gratings that work in reflection. LLNL has developed processing capability to produce high efficiency fused silica transmission gratings at sizes useful to future Petawatt-class systems, and has demonstrated high efficiency at smaller aperture. This report shows that fused silica diffraction exhibiting >95% efficiency into the -1 diffraction order in transmission (90{sup o} deflection of the incident light, at an incidence angle of 45{sup o} to the grating face). The microstructure of this grating consisted of grooves ion-beam etched to a depth of 1.6 microns with a pitch of 0.75 microns, using a holographically produced photoresist mask that was subsequently stripped away in significance to the fabrication of the small scale high efficiency grating was the development of the processing technology and infrastructure for production of such gratings at up to 65 cm diameter. LLNL is the currently the only location in the world with the ability to coat, interferometrically expose, and ion etch diffractive optics at this aperture. Below, we describe the design, fabrication, performance and, the scaleup process for a producing a high-efficiency transmission grating on a 65 cm fused silica substrate.

  19. Case for segmentation of the primary mirror of large-aperture space telescopes

    NASA Astrophysics Data System (ADS)

    Montgomery, Edward E.; Zeiders, Glenn W.

    1998-08-01

    The hypothesis is tested: space telescopes with apertures larger than a few meters will have lower mass and cost and better optical performance if the primary mirror is aggressively segmented. Optical performance variations are considered from several factors including the gap between regular hexagonal mirror segments, the relative ability of different size to be manufactured with low wavefront error, and expected mirror deformations. A mass variation is derived to relate diameter and thickness of the mirror segments to satisfy mirror deflections and thermally induced stress. Mass estimation includes support structures, actuators, cabling, electronics, hinges, and latches. Cost is evaluated from several models previously proposed to address multiple mirror systems. The analyses conclude that there is a relatively-small optimum segment size that is independent of the dimensions of the overall array but which does depend upon the state of technology. It is further shown that a significant mass penalty will be incurred for segments that are either smaller or larger than the optimum size. Minimum mirror thickness is constrained, but engineering design principles for structural deflections and model frequencies otherwise dictate the design.

  20. Optical and Thermal Behaviors of Plasmonic Bowtie Aperture and Its NSOM Characterization for Heat-Assisted Magnetic Recording

    DTIC Science & Technology

    2016-02-01

    IEEE TRANSACTIONS ON MAGNETICS, VOL. 52, NO. 2, FEBRUARY 2016 1100105 Optical and Thermal Behaviors of Plasmonic Bowtie Aperture and Its NSOM...diffraction-limited region in the recording medium. The NFTs made of plasmonic nanoscale optical antennas provide the capability of sub-wavelength light...manipulation at optical frequencies. These antennas are designed using both plasmonic resonance and localized plasmons to produce an enhanced field in an

  1. The Balloon-borne Large Aperture Submillimetre Telescope (BLAST) and BLASTPol

    NASA Astrophysics Data System (ADS)

    Pascale, Enzo; Pascale

    2013-01-01

    Balloon observations from Antarctica have proven an effective and efficient way to address open Cosmological questions as well as problems in Galactic astronomy. The Balloon-borne Large Aperture Submillimetre Telescope (BLAST) is a sub-orbital mapping experiment which uses 270 bolometric detectors to image the sky in three wavebands centred at 250, 350 and 500 μm with a 1.8 m telescope. In the years before Herschel launched, BLAST provided data of unprecedented angular and spectral coverage in frequency bands close to the peak of dust emission in star forming regions in our Galaxy, and in galaxies at cosmological distances. More recently, BLASTPol was obtained by reconfiguring the BLAST focal plane as a submillimetric polarimeter to study the role that Galactic magnetic fields have in regulating the processes of star-formation. The first and successful BLASTPol flight from Antarctica in 2010 is followed by a second flight, currently scheduled for the end of 2012.

  2. The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) 2005: Calibration and Targeted Sources

    NASA Astrophysics Data System (ADS)

    Truch, Matthew; BLAST Collaboration

    2007-12-01

    The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) operated successfully during a 100-hour flight from northern Sweden in June 2005 (BLAST05). As part of the calibration and pointing procedures, several compact sources were mapped, including solar system, Galactic, and extragalactic targets, specifically Pallas, CRL 2688, LDN 1014, IRAS 20126+4104, IRAS 21078+5211, IRAS 21307+5049, IRAS 22134+5834, IRAS 23011+6126, K3-50, W 75N, Mrk 231, NGC 4565, and Arp 220 (this last source being our primary calibrator). The BLAST observations of each compact source are described, flux densities and spectral energy distributions are reported, and these are compared with previous measurements at other wavelengths. BLAST was particularly useful for constraining the slope of the submillimeter continuum.

  3. A New Technique Producing Double-Sided Spherical Fresnel Lens Segments Assembled to Large Aperture Lenses

    NASA Astrophysics Data System (ADS)

    Ohmori, H.; Takahashi, Y.; Shimizu, H.; Uehara, Y.; Suzuki, T.; Ueno, Y.; Hillman, L. W.; Zuccaro, A.; EUSO Collaboration

    2003-07-01

    A new technique of molding of lens segments has been developed to produce a large, double-sided, curved Fresnel lenses for refractive telescopes. The molding process involves two steps of spherically curved plate formation and lens gro ove transfer onto the curved plate. These molding process have been carried out with two sides of the diamond-cut dies set in the hydraulic press machine at elevated temperatures to the lens material that is a transparent UV-acrylic of Mitsubishi. Ultra-precision dies were made of oxygen-free copp er, which were cut by diamond to ols to make Fresnel facets. A four-axis ultra-precision cutting machine has been developed first to manufacture ultra-precision mold dies. Double-sided, curved Fresnel lens segments will be used as circumference petals of lenses of 2500mm aperture surrounding a 1500mm diameter central lens.

  4. OASIS 1.0: Very Large-Aperture High-Power Lidar for Exploring Geospace

    NASA Astrophysics Data System (ADS)

    Chu, X.; Smith, J. A.; Chen, C.; Zhao, J.; Yu, Z.; Gardner, C. S.

    2015-12-01

    A new initiative, namely OASIS (the Observatory for Atmosphere Space Interaction Studies), has called for a very large-aperture high-power (VLAHP) lidar as its first step forward to acquire the unprecedented measurement capabilities for exploring the space-atmosphere interaction region (SAIR). Currently, there exists a serious observational gap of the Earth's neutral atmosphere above 100 km. Information on neutral winds and temperatures and on the plasma-neutral coupling in the SAIR, especially between 100 and 200 km, is either sparse or nonexistent. Fully exploring the SAIR requires measurements of the neutral atmosphere to complement radar observations of the plasma. Lidar measurements of neutral winds, temperatures and species can enable these explorations. Many of these topics will be addressed with the VLAHP lidar. Discoveries of thermospheric neutral Fe, Na and K layers up to nearly 200 km at McMurdo, Antarctica and other locations on Earth, have opened a new door to observing the neutral thermosphere with ground-based instruments. These neutral metal layers provide the tracers for resonance Doppler lidars to directly measure the neutral temperatures and winds in the thermosphere, thus enabling the VLAHP lidar dream! Because the thermospheric densities of these metal atoms are many times smaller than the layer peak densities near 90 km, high power-aperture product lidars, like the VLAHP lidar, are required to derive scientifically useful measurements. Furthermore, several key technical challenges for VLAHP lidar have been largely resolved in the last a few years through the successful development of Fe and Na Doppler lidars at Boulder. By combining Rayleigh and Raman with resonance lidar techniques and strategically operating the VLAHP lidar next to incoherent scatter radar and other complementary instruments, the VLAHP lidar will enable new cutting-edge exploration of the geospace. These new concepts and progresses will be introduced in this paper.

  5. Large Diffractive Optics for GEo-Based Earth Surveillance

    SciTech Connect

    Hyde, R A

    2003-09-11

    The natural vantage point for performing Earth-centric operations from space is geosynchronous orbit (GEO); a platform there moves at the same rate as the Earth's surface, so appears to continually ''hover'' over a fixed site on the Earth. Unlike spacecraft in other orbits, which rapidly fly-over targets, a GEO-based platform remains in-position all the time. In order to insure continual access to sites using low earth orbit (LEO) platforms, one needs a large enough constellation ({approx} 50) of spacecraft so that one is always overhead; in contrast, a single GEO platform provides continuous coverage over sites throughout Euro-Asia. This permanent coverage comes, unfortunately, with a stiff price-tag; geosynchronous orbit is 36,000 km high, so space platforms there must operate at ranges roughly 100 times greater than ones located in LEO. For optical-based applications, this extreme range is difficult to deal with; for surveillance the price is a 100-fold loss of resolution, for laser weapons it is a 10,000-fold loss in flux-on-target. These huge performance penalties are almost always unacceptable, preventing us from successfully using GEO-based platforms. In practice, we are forced to either settle for brief, infrequent access to targets, or, if we demand continuous coverage, to invest in large, many-satellite, constellations. There is, fortunately, a way to use GEO-based optical platforms without incurring the huge, range-dependent, performance penalties; one must simply use bigger optics. As long as the aperture of a platform's optics increases as much as its operating range, then its performance (resolution and/or flux) does not suffer; the price for operating from GEO is simply 100-fold larger optics. This is, of course, a very stiff price; while meter-class optics may suffice for many low-earth-orbit applications, 100 meter apertures are needed in order to achieve similar performance from GEO. Since even the largest Earth-based telescope is only 10 meters

  6. Solar tower cavity receiver aperture optimization based on transient optical and thermo-hydraulic modeling

    NASA Astrophysics Data System (ADS)

    Schöttl, Peter; Bern, Gregor; van Rooyen, De Wet; Heimsath, Anna; Fluri, Thomas; Nitz, Peter

    2017-06-01

    A transient simulation methodology for cavity receivers for Solar Tower Central Receiver Systems with molten salt as heat transfer fluid is described. Absorbed solar radiation is modeled with ray tracing and a sky discretization approach to reduce computational effort. Solar radiation re-distribution in the cavity as well as thermal radiation exchange are modeled based on view factors, which are also calculated with ray tracing. An analytical approach is used to represent convective heat transfer in the cavity. Heat transfer fluid flow is simulated with a discrete tube model, where the boundary conditions at the outer tube surface mainly depend on inputs from the previously mentioned modeling aspects. A specific focus is put on the integration of optical and thermo-hydraulic models. Furthermore, aiming point and control strategies are described, which are used during the transient performance assessment. Eventually, the developed simulation methodology is used for the optimization of the aperture opening size of a PS10-like reference scenario with cavity receiver and heliostat field. The objective function is based on the cumulative gain of one representative day. Results include optimized aperture opening size, transient receiver characteristics and benefits of the implemented aiming point strategy compared to a single aiming point approach. Future work will include annual simulations, cost assessment and optimization of a larger range of receiver parameters.

  7. Large core fiber optic cleaver

    DOEpatents

    Halpin, J.M.

    1996-03-26

    The present invention relates to a device and method for cleaving optical fibers which yields cleaved optical fiber ends possessing high damage threshold surfaces. The device can be used to cleave optical fibers with core diameters greater than 400 {micro}m. 30 figs.

  8. Large core fiber optic cleaver

    DOEpatents

    Halpin, John M.

    1996-01-01

    The present invention relates to a device and method for cleaving optical fibers which yields cleaved optical fiber ends possessing high damage threshold surfaces. The device can be used to cleave optical fibers with core diameters greater than 400 .mu.m.

  9. Lightweight optical barrel assembly structures for large deployable space telescopes

    NASA Astrophysics Data System (ADS)

    Warren, Peter A.; Silver, Mark J.; Dobson, Benjamin J.

    2009-08-01

    Future space based telescopes will need apertures and focal lengths that exceed the dimensions of the launch vehicle shroud. In addition to deploying the primary mirror and secondary mirror support structure, these large telescopes must also deploy the stray light and thermal barriers needed to ensure proper telescope performance. The authors present a deployable light and thermal optical barrel assembly approach for a very large telescope with a variable sun angle and fast slew rate. The Strain Energy Deployable Optical Barrel Assembly (SEDOBA) uses elastic composite hinges to power the deployment of a hierarchical truss structure that supports the thermal and stray light shroud material that form the overall system. The paper describes the overall design approach, the key component technologies, and the design and preliminary testing of a self deploying scale model prototype.

  10. Construction and Characterization of a Large Aperture Blackbody for Infrared Radiometer Calibration

    NASA Astrophysics Data System (ADS)

    Park, Chul-Woung; Yoo, Yong Shim; Kim, Bong-Hak; Chun, Sejong; Park, Seung-Nam

    2011-08-01

    A large aperture blackbody (LABB) with a diameter of 1 m has been successfully constructed for calibrating radiation thermometers and infrared radiometers with a wide field of view in the temperature range between 10 °C and 90 °C. The blackbody is a 1 m long cylindro-conical cavity with a diameter of 1.1 m. Its conical bottom has an apex angle of 120°. To achieve good temperature stability and uniformity, the cavity is integrated to a water-bath to which the pressurized water is supplied from a reservoir. To reduce the convection heat loss from the cavity to the ambient, the cavity is purged of the dried air that passes through a coiled tube immersed in the reservoir. For an uncertainty evaluation of the LABB, its temperature stability was measured by using a reference radiation thermometer (RRT) and a platinum resistance thermometer (PRT), and its radiance temperature distributions on the aperture plane were measured by using a thermal camera. Measuring the spectral emissivity of the coating material, the effective emissivity of the blackbody was calculated to be 0.9955 from 1 μm to 15 μm. The expanded uncertainty of the radiance temperature scale was evaluated based on the PRT readings, which vary from 0.3 °C to 0.5 °C ( k = 2) in the temperature range. The temperature scale is validated by comparing with the RRT of which the temperature scale is realized by a multiple fixed-point calibration.

  11. Hybrid Electrostatic/Flextensional Mirror for Lightweight, Large-Aperture, and Cryogenic Space Telescopes

    NASA Technical Reports Server (NTRS)

    Patrick, Brian; Moore, James; Hackenberger, Wesley; Jiang, Xiaoning

    2013-01-01

    A lightweight, cryogenically capable, scalable, deformable mirror has been developed for space telescopes. This innovation makes use of polymer-based membrane mirror technology to enable large-aperture mirrors that can be easily launched and deployed. The key component of this innovation is a lightweight, large-stroke, cryogenic actuator array that combines the high degree of mirror figure control needed with a large actuator influence function. The latter aspect of the innovation allows membrane mirror figure correction with a relatively low actuator density, preserving the lightweight attributes of the system. The principal components of this technology are lightweight, low-profile, high-stroke, cryogenic-capable piezoelectric actuators based on PMN-PT (piezoelectric lead magnesium niobate-lead titanate) single-crystal configured in a flextensional actuator format; high-quality, low-thermal-expansion polymer membrane mirror materials developed by NeXolve; and electrostatic coupling between the membrane mirror and the piezoelectric actuator assembly to minimize problems such as actuator print-through.

  12. Remote optical sensing on the nanometer scale with a bowtie aperture nano-antenna on a fiber tip of scanning near-field optical microscopy

    SciTech Connect

    Atie, Elie M.; Xie, Zhihua; El Eter, Ali; Salut, Roland; Baida, Fadi I.; Grosjean, Thierry; Nedeljkovic, Dusan; Tannous, Tony

    2015-04-13

    Plasmonic nano-antennas have proven the outstanding ability of sensing chemical and physical processes down to the nanometer scale. Sensing is usually achieved within the highly confined optical fields generated resonantly by the nano-antennas, i.e., in contact to the nanostructures. In this paper, we demonstrate the sensing capability of nano-antennas to their larger scale environment, well beyond their plasmonic confinement volume, leading to the concept of “remote” (non contact) sensing on the nanometer scale. On the basis of a bowtie-aperture nano-antenna (BNA) integrated at the apex of a SNOM (Scanning Near-field Optical Microscopy) fiber tip, we introduce an ultra-compact, moveable, and background-free optical nanosensor for the remote sensing of a silicon surface (up to distance of 300 nm). Sensitivity of the BNA to its large scale environment is high enough to expect the monitoring and control of the spacing between the nano-antenna and a silicon surface with sub-nanometer accuracy. This work paves the way towards an alternative class of nanopositioning techniques, based on the monitoring of diffraction-free plasmon resonance, that are alternative to nanomechanical and diffraction-limited optical interference-based devices.

  13. A CLOSE COMPANION SEARCH AROUND L DWARFS USING APERTURE MASKING INTERFEROMETRY AND PALOMAR LASER GUIDE STAR ADAPTIVE OPTICS

    SciTech Connect

    Bernat, David; Bouchez, Antonin H.; Cromer, John L.; Dekany, Richard G.; Moore, Anna M.; Ireland, Michael; Tuthill, Peter; Martinache, Frantz; Angione, John; Burruss, Rick S.; Guiwits, Stephen R.; Henning, John R.; Hickey, Jeff; Kibblewhite, Edward; McKenna, Daniel L.; Petrie, Harold L.; Roberts, Jennifer; Shelton, J. Chris; Thicksten, Robert P.; Trinh, Thang

    2010-06-01

    We present a close companion search around 16 known early L dwarfs using aperture masking interferometry with Palomar laser guide star adaptive optics (LGS AO). The use of aperture masking allows the detection of close binaries, corresponding to projected physical separations of 0.6-10.0 AU for the targets of our survey. This survey achieved median contrast limits of {Delta}K {approx} 2.3 for separations between 1.2 {lambda}/D-4{lambda}/D and {Delta}K {approx} 1.4 at 2/3 {lambda}/D. We present four candidate binaries detected with moderate-to-high confidence (90%-98%). Two have projected physical separations less than 1.5 AU. This may indicate that tight-separation binaries contribute more significantly to the binary fraction than currently assumed, consistent with spectroscopic and photometric overluminosity studies. Ten targets of this survey have previously been observed with the Hubble Space Telescope as part of companion searches. We use the increased resolution of aperture masking to search for close or dim companions that would be obscured by full aperture imaging, finding two candidate binaries. This survey is the first application of aperture masking with LGS AO at Palomar. Several new techniques for the analysis of aperture masking data in the low signal-to-noise regime are explored.

  14. Large-explosive source, wide-recording aperture, seismic profiling on the Columbia Plateau, Washington

    SciTech Connect

    Jarchow, C.M. . Dept. of Geophysics); Catchings, R.D.; Lutter, W.J. )

    1994-02-01

    Clear subsurface seismic images have been obtained at low cost on the Columbia Plateau, Washington. The Columbia Plateau is perhaps the most notorious of all bad-data'' areas because large impedance contrasts in surface flood basalts severely degrade the seismic wavefield. This degradation was mitigated in this study via a large-explosive source, wide-recording aperture shooting method. The shooting method emphasizes the wide-angle portion of the wavefield, where Fermat's principle guarantees reverberation will not interfere with the seismic manifestations of crucial geologic interfaces. The basalt diving wave, normally discarded in standard common midpoint (CMP) seismic profiling, can be used to image basalt velocity structure via travel-time inversion. Maximum depth-penetration of the diving wave tightly constrains basalt-sediment interface depth. An arrival observed only at shot-receiver offsets greater than 15 km can be used to determine the velocity and geometry of basement via simultaneous inversion. The results from this study suggest that previous geologic hypotheses and hydrocarbon play concepts for the Columbia Plateau may have been in error.

  15. Large-explosive source, wide-recording aperture, seismic profiling on the Columbia Plateau, Washington

    USGS Publications Warehouse

    Jarchow, Craig M.; Catchings, Rufus D.; Lutter, William J.

    1994-01-01

    Clear subsurface seismic images have been obtained at low cost on the Columbia Plateau, Washington. The Columbia Plateau is perhaps the most notorious of all 'bad-data' areas because large impedance contrasts in surface flood basalts severely degrade the seismic wavefield. This degradation was mitigated in this study via a large-explosive source, wide-recording aperture shooting method.The shooting method emphasizes the wide-angle portion of the wavefield, where Fermat's principle guarantees reverberation will not interfere with the seismic manifestations of crucial geologic interfaces. The basalt diving wave, normally discarded in standard common midpoint (CMP) seismic profiling, can be used to image basalt velocity structure via traveltime inversion. Maximum depth-penetration of the diving wave tightly constrains basalt-sediment interface depth. An arrival observed only at shot-receiver offsets greater than 15 km can be used to determine the velocity and geometry of basement via simultaneous inversion.The results from this study suggest that previous geologic hypotheses and hydrocarbon play concepts for the Columbia Plateau may have been in error.

  16. A scalable multi-chip architecture to realise large-format microshutter arrays for coded aperture applications

    NASA Astrophysics Data System (ADS)

    McNie, Mark E.; King, David O.; Smith, Gilbert W.; Stone, Steven M.; Brown, Alan G.; Gordon, Neil T.; Slinger, Christopher W.; Cannon, Kevin; Riches, Stephen; Rogers, Stanley

    2009-08-01

    Coded aperture imaging has been used for astronomical applications for several years. Typical implementations used a fixed mask pattern and are designed to operate in the X-Ray or gamma ray bands. Recently applications have emerged in the visible and infra red bands for low cost lens-less imaging systems and system studies have shown that considerable advantages in image resolution may accrue from the use of multiple different images of the same scene - requiring a reconfigurable mask. Previously we reported on the realization of a 2x2cm single chip mask in the mid-IR based on polysilicon micro-opto-electro-mechanical systems (MOEMS) technology and its integration with ASIC drive electronics using conventional wire bonding. The MOEMS architecture employs interference effects to modulate incident light - achieved by tuning a large array of asymmetric Fabry-Perot optical cavities via an applied voltage and uses a hysteretic row/column scheme for addressing. In this paper we present the latest transmission results in the mid-IR band (3-5μm) and report on progress in developing a scalable architecture based on a tiled approach using multiple 2 x 2cm MOEMS chips with associated control ASICs integrated using flip chip technology. Initial work has focused on a 2 x 2 tiled array as a stepping stone towards an 8 x 8 array.

  17. The ExaVolt Antenna: A large-aperture, balloon-embedded antenna for ultra-high energy particle detection

    NASA Astrophysics Data System (ADS)

    Gorham, P. W.; Baginski, F. E.; Allison, P.; Liewer, K. M.; Miki, C.; Hill, B.; Varner, G. S.

    2011-12-01

    We describe the scientific motivation, experimental basis, design methodology, and simulated performance of the ExaVolt Antenna (EVA) mission, and planned ultra-high energy (UHE) particle observatory under development for NASA's suborbital super-pressure balloon program in Antarctica. EVA will improve over ANITA's integrated totals - the current state-of-the-art in UHE suborbital payloads - by 1-2 orders of magnitude in a single flight. The design is based on a novel application of toroidal reflector optics which utilizes a super-pressure balloon surface, along with a feed-array mounted on an inner membrane, to create an ultra-large radio antenna system with a synoptic view of the Antarctic ice sheet below it. Radio impulses arise via the Askaryan effect when UHE neutrinos interact within the ice, or via geosynchrotron emission when UHE cosmic rays interact in the atmosphere above the continent. EVA's instantaneous antenna aperture is estimated to be several hundred m 2 for detection of these events within a 150-600 MHz band. For standard cosmogenic UHE neutrino models, EVA should detect of order 30 events per flight in the EeV energy regime. For UHE cosmic rays, of order 15,000 geosynchrotron events would be detected in total, several hundred above 10 EeV, and of order 60 above the GZK cutoff energy.

  18. The next generation balloon-borne large aperture submillimeter telescope (BLAST-TNG)

    NASA Astrophysics Data System (ADS)

    Dober, Bradley Jerald

    Large areas of astrophysics, such as precision cosmology, have benefited greatly from large maps and datasets, yielded by telescopes of ever-increasing number and ability. However, due to the unique challenges posed by submillimeter polarimetry, the study of molecular cloud dynamics and star formation remain stunted. Previously, polarimetry data was limited to a few vectors on only the brightest areas of molecular clouds. This made drawing statistically-driven conclusions a daunting task. However, the successful flight of the Balloon-born Large Aperture Submillimeter Telescope for Polarimetry (BLASTPol) generated maps with thousands of independent polarization measurements of molecular clouds, and ushered in a new era of empirical modeling of molecular cloud dynamics. Now that the potential benefits from large-scale maps of magnetic fields in molecular clouds had been identified, a successor that would truly unlock the secrets must be born. The Next Generation Balloon-borne Large Aperture Submillimeter Telescope (BLAST-TNG), the successor to BLASTPol, has the ability to make larger and more detailed maps of magnetic fields in molecular clouds. It will push the field of star formation into a statistics-driven, empirical realm. With these large, detailed datasets, astronomers will be able to find new relationships between the dust dynamics and the magnetic fields. The field will surge to a new level of understanding. One of the key enabling technologies of BLAST-TNG is its three arrays of polarization-sensitive Microwave Kinetic Inductance Detectors (MKIDs). MKIDs are superconducting RLC circuits with a resonant frequency that shifts proportionally to the amount of incident radiation. The key feature of MKIDs is that thousands of detectors, each with their own unique resonant frequency, can be coupled to the same readout line. This technology will be able to drive the production of large-scale monolithic arrays, containing tens or hundreds of thousands of detectors

  19. A New Type of X-ray Condenser Lenses with Large Apertures Fabricated by Rolling of Structured Films

    SciTech Connect

    Simon, M.; Reznikova, E.; Nazmov, V.; Grund, T.; Last, A.

    2010-04-06

    In order to meet the demand for X-ray lenses with large apertures and, hence, photon flux, a new type of X-ray lenses has been developed: Rolled prismatic X-ray lenses feature a vast number of refracting surfaces to increase transparency and aperture, respectively. Prototypes of such lenses have been fabricated by molding and rolling of a structured polyimide film. In this work, rolled prismatic X-ray lenses are pictured, and results of first tests performed at the ANKA storage ring in Karlsruhe are presented.

  20. Large-scale silicon optical switches for optical interconnection

    NASA Astrophysics Data System (ADS)

    Qiao, Lei; Tang, Weijie; Chu, Tao

    2016-11-01

    Large-scale optical switches are greatly demanded in building optical interconnections in data centers and high performance computers (HPCs). Silicon optical switches have advantages of being compact and CMOS process compatible, which can be easily monolithically integrated. However, there are difficulties to construct large ports silicon optical switches. One of them is the non-uniformity of the switch units in large scale silicon optical switches, which arises from the fabrication error and causes confusion in finding the unit optimum operation points. In this paper, we proposed a method to detect the optimum operating point in large scale switch with limited build-in power monitors. We also propose methods for improving the unbalanced crosstalk of cross/bar states in silicon electro-optical MZI switches and insertion losses. Our recent progress in large scale silicon optical switches, including 64 × 64 thermal-optical and 32 × 32 electro-optical switches will be introduced. To the best our knowledge, both of them are the largest scale silicon optical switches in their sections, respectively. The switches were fabricated on 340-nm SOI substrates with CMOS 180- nm processes. The crosstalk of the 32 × 32 electro-optic switch was -19.2dB to -25.1 dB, while the value of the 64 × 64 thermal-optic switch was -30 dB to -48.3 dB.

  1. Design studies of large aperture, high-resolution Earth science microwave radiometers compatible with small launch vehicles

    NASA Technical Reports Server (NTRS)

    Schroeder, Lyle C.; Bailey, M. C.; Harrington, Richard F.; Kendall, Bruce M.; Campbell, Thomas G.

    1994-01-01

    High-spatial-resolution microwave radiometer sensing from space with reasonable swath widths and revisit times favors large aperture systems. However, with traditional precision antenna design, the size and weight requirements for such systems are in conflict with the need to emphasize small launch vehicles. This paper describes tradeoffs between the science requirements, basic operational parameters, and expected sensor performance for selected satellite radiometer concepts utilizing novel lightweight compactly packaged real apertures. Antenna, feed, and radiometer subsystem design and calibration are presented. Preliminary results show that novel lightweight real aperture coupled with state-of-the-art radiometer designs are compatible with small launch systems, and hold promise for high-resolution earth science measurements of sea ice, precipitation, soil moisture, sea surface temperature, and ocean wind speeds.

  2. Ray-tracing and physical-optics analysis of the aperture efficiency in a radio telescope

    NASA Astrophysics Data System (ADS)

    Olmi, Luca; Bolli, Pietro

    2007-07-01

    The performance of telescope systems working at microwave or visible-IR wavelengths is typically described in terms of different parameters according to the wavelength range. Most commercial ray-tracing packages have been specifically designed for use with visible-IR systems and thus, though very flexible and sophisticated, do not provide the appropriate parameters to fully describe microwave antennas and to compare with specifications. We demonstrate that the Strehl ratio is equal to the phase efficiency when the apodization factor is taken into account. The phase efficiency is the most critical contribution to the aperture efficiency of an antenna and the most difficult parameter to optimize during the telescope design. The equivalence between the Strehl ratio and the phase efficiency gives the designer/user of the telescope the opportunity to use the faster commercial ray-tracing software to optimize the design. We also discuss the results of several tests performed to check the validity of this relationship that we carried out using a ray-tracing software, ZEMAX, and a full Physical Optics software, GRASP9.3, applied to three different telescope designs that span a factor of ≃10 in terms of D/λ. The maximum measured discrepancy between phase efficiency and Strehl ratio varies between ≃0.4% and 1.9% up to an offset angle of >40 beams, depending on the optical configuration, but it is always less than 0.5% where the Strehl ratio is >0.95.

  3. Synthetic Aperture Radar (sar) and Optical Imagery Data Fusion: Crop Yield Analysis in Southeast Asia

    NASA Astrophysics Data System (ADS)

    Parks, S. M.

    2012-08-01

    With the expanding energy crisis and rising food prices, crop yield analysis in Southeast Asia is an increasingly important topic in this region. Rice is the most important food crop in Southeast Asia and the ability to accurately predict crop yields during a growing season is useful for decision-makers, aid providers, and commercial trade organizations. The use of optical satellite image data by itself is difficult due to the almost constant cloud in many parts of Southeast Asia. However, Synthetic Aperture Radar (SAR), or SAR data, which can image the Earth's surface through cloud cover, is suitable for many agricultural purposes, such as the detection of rice fields, and the identification of different crop species. Crop yield analysis is difficult in this region due to many factors. Rice cropping systems are often characterized by the type of rice planted, the size of rice field, the sowing dates for different fields, different types of rice cropping systems from one area to another, as well as cultural practices such as sowing and transplanting. This paper will discuss the use of SAR data fused with optical imagery to improve the ability to perform crop yield analysis on rice crops in Southeast Asia.

  4. Ray-tracing and physical-optics analysis of the aperture efficiency in a radio telescope.

    PubMed

    Olmi, Luca; Bolli, Pietro

    2007-07-01

    The performance of telescope systems working at microwave or visible-IR wavelengths is typically described in terms of different parameters according to the wavelength range. Most commercial ray-tracing packages have been specifically designed for use with visible-IR systems and thus, though very flexible and sophisticated, do not provide the appropriate parameters to fully describe microwave antennas and to compare with specifications. We demonstrate that the Strehl ratio is equal to the phase efficiency when the apodization factor is taken into account. The phase efficiency is the most critical contribution to the aperture efficiency of an antenna and the most difficult parameter to optimize during the telescope design. The equivalence between the Strehl ratio and the phase efficiency gives the designer/user of the telescope the opportunity to use the faster commercial ray-tracing software to optimize the design. We also discuss the results of several tests performed to check the validity of this relationship that we carried out using a ray-tracing software, ZEMAX, and a full Physical Optics software, GRASP9.3, applied to three different telescope designs that span a factor of approximately 10 in terms of D/lambda. The maximum measured discrepancy between phase efficiency and Strehl ratio varies between approximately 0.4% and 1.9% up to an offset angle of >40 beams, depending on the optical configuration, but it is always less than 0.5% where the Strehl ratio is >0.95.

  5. Aperture scanning near-field optical microscopy and spectroscopy of single terrylene molecules at 1.8 K.

    PubMed

    Butter, J Y P; Hecht, B

    2006-03-28

    Single-molecule imaging and spectroscopy using an aperture scanning near-field optical microscope operating at 1.8 K in a helium bath cryostat is demonstrated. From near-field images at constant excitation frequency, the orientation of single molecules can be deduced. Spectral information is obtained using both near-field and confocal excitation schemes by scanning the excitation frequency at a fixed sample position. Differences between near-field and confocal spectra are discussed in terms of the position with respect to the aperture and the molecular orientation.

  6. Numerical and experimental study of near-field scanning optical lithography using nanoscale bowtie apertures with ultrasmall gap size

    NASA Astrophysics Data System (ADS)

    Ding, Li; Qin, Jin; Chen, Yang; Wang, Liang

    2016-07-01

    Nanoscale ridge apertures have been demonstrated to be applied for high-resolution lithography. We performed a numerical study of nanoscale bowtie apertures with different outline dimensions and gap sizes to analyze their detailed field distribution for near-field scanning optical lithography (NSOL). It is found that the high image contrast, which is necessary for good quality lithography, is obtained in the near-field region and decays quickly with increasing distance. Furthermore, a smaller gap size achieves higher image contrast and deeper depth of focus. With the NSOL system, static and scanning lithography experiments are conducted. Combined with the passive flexure stage for contact control, we achieved 18-nm lithography resolution.

  7. Measuring large optical reflection matrices of turbid media

    NASA Astrophysics Data System (ADS)

    Yu, Hyeonseung; Park, Jung-Hoon; Park, YongKeun

    2015-10-01

    We report the measurement of a large optical reflection matrix (RM) of a highly disordered medium. Incident optical fields onto a turbid sample are controlled by a spatial light modulator, and the corresponding fields reflected from the sample are measured using full-field Michelson interferometry. The number of modes in the measured RM is set to exceed the number of resolvable modes in the scattering media. We successfully study the subtle intrinsic correlations in the RM which agrees with the theoretical prediction by the random-matrix theory when the effect of the limited numerical aperture on the eigenvalue distribution of the RM is taken into account. The possibility of the enhanced delivery of incident energy into scattering media is also examined from the eigenvalue distribution which promises efficient light therapeutic applications.

  8. Estimation of turbulent sensible heat and momentum fluxes over a heterogeneous urban area using a large aperture scintillometer

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Hyun; Lee, Jun-Ho; Kim, Bo-Young

    2015-08-01

    The accurate determination of surface-layer turbulent fluxes over urban areas is critical to understanding urban boundary layer (UBL) evolution. In this study, a remote-sensing technique using a large aperture scintillometer (LAS) was investigated to estimate surface-layer turbulent fluxes over a highly heterogeneous urban area. The LAS system, with an optical path length of 2.1 km, was deployed in an urban area characterized by a complicated land-use mix (residential houses, water body, bare ground, etc.). The turbulent sensible heat ( Q H) and momentum fluxes (τ) were estimated from the scintillation measurements obtained from the LAS system during the cold season. Three-dimensional LAS footprint modeling was introduced to identify the source areas ("footprint") of the estimated turbulent fluxes. The analysis results showed that the LAS-derived turbulent fluxes for the highly heterogeneous urban area revealed reasonable temporal variation during daytime on clear days, in comparison to the land-surface process-resolving numerical modeling. A series of sensitivity tests indicated that the overall uncertainty in the LAS-derived daytime Q H was within 20%-30% in terms of the influence of input parameters and the nondimensional similarity function for the temperature structure function parameter, while the estimation errors in τ were less sensitive to the factors of influence, except aerodynamic roughness length. The 3D LAS footprint modeling characterized the source areas of the LAS-derived turbulent fluxes in the heterogeneous urban area, revealing that the representative spatial scales of the LAS system deployed with the 2.1 km optical path distance ranged from 0.2 to 2 km2 (a "micro- a scale"), depending on local meteorological conditions.

  9. A procedure for combining rotating-coil measurements of large-aperture accelerator magnets

    NASA Astrophysics Data System (ADS)

    Köster, Oliver; Fiscarelli, Lucio; Russenschuck, Stephan

    2016-05-01

    The rotating search coil is a precise and widely used tool for measuring the magnetic field harmonics of accelerator magnets. This paper deals with combining several such multipole measurements, in order to cover magnet apertures largely exceeding the diameter of the available search coil. The method relies on the scaling laws for multipole coefficients and on the method of analytic continuation along zero-homotopic paths. By acquiring several measurements of the integrated magnetic flux density at different transverse positions within the bore of the accelerator magnet, the uncertainty on the field harmonics can be reduced at the expense of tight tolerances on the positioning. These positioning tolerances can be kept under control by mounting the rotating coil and its motor-drive unit on precision alignment stages. Therefore, the proposed technique is able to yield even more precise results for the higher-order field components than a dedicated rotating search coil of larger diameter. Moreover, the versatility of the measurement bench is enhanced by avoiding the construction of rotating search coils of different measurement radii.

  10. Distribution-dependent total exoplanet yield for a large aperture space telescope

    NASA Astrophysics Data System (ADS)

    Morris, Evan; Schiminovich, David

    2017-01-01

    A major scientific goal for future large aperture space telescopes is the discovery and characterization of habitable earth-like planets around FGK+M stars out to 10-20 pc. Using the design and observing plan for such a mission, we calculated the total exoplanet yield of a direct imaging survey, with detections including but not limited to potential earth analogs. In light of uncertainty of exoplanet occurrence rates, we used several of the best available exoplanetary distribution functions and assumed architectures to produce a Monte Carlo simulation of nearby planetary systems and observational parameters, and assessed detectability across the sample. Our calculations show a range of yields depending on the assumed distribution functions. We also compare our predictions to those of other detection methods in order to identify areas of parameter space (e.g. radius, period) uniquely constrained by direct imaging. In general, our calculations suggest that a higher completeness can be achieved with direct imaging, which will allow for calculation of a more accurate occurrence rate in local space.

  11. Microstrip patch antenna panel for large aperture L-band phased array

    NASA Technical Reports Server (NTRS)

    Chamberlain, Neil; Amaro, Luis; Oakes, Eric; Hodges, Richard; Spitz, Suzanne; Rosen, Paul A.

    2004-01-01

    This paper describes the design and development of a large, lightweight antenna panel for an active phased array operating at L-band. The panel was developed under a JPL program of technology development for space based radar. It utilizes dual-stacked patch elements that are interconnected with corporate feed manifold of striplines. This paper focuses on the electromagnetic design and performance of the radiating elements, with emphasis on scan performance, and also addresses mechanical and thermal aspects of the panel. The element in the array environment has a bandwidth of more than 80MHz centered at 1260MHz and is fed so that it can radiate orthogonal linear polarizations. The envisioned phased array, with a nominal aperture of 50m x 2m, is designed to scan +/-45 degrees in azimuth and +/-20 degrees in elevation. The panel of radiating elements has a mass density of 3.9 kg/m2, which represents approximately 50% of the target 8kg/m2 total panel mass density that includes T/R modules and feed manifolds.

  12. The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) 2005: Calibration and Targeted Sources

    NASA Astrophysics Data System (ADS)

    Truch, M. D. P.; Ade, P. A. R.; Bock, J. J.; Chapin, E. L.; Devlin, M. J.; Dicker, S.; Griffin, M.; Gundersen, J. O.; Halpern, M.; Hargrave, P. C.; Hughes, D. H.; Klein, J.; Marsden, G.; Martin, P. G.; Mauskopf, P.; Netterfield, C. B.; Olmi, L.; Pascale, E.; Patanchon, G.; Rex, M.; Scott, D.; Semisch, C.; Tucker, C.; Tucker, G. S.; Viero, M. P.; Wiebe, D. V.

    2008-07-01

    The Balloon-borne Large Aperture Submillimeter Telescope (BLAST) operated successfully during a 100 hr flight from northern Sweden in 2005 June (BLAST05). As part of the calibration and pointing procedures, several compact sources were mapped, including solar system, Galactic, and extragalactic targets, specifically Pallas, CRL 2688, LDN 1014, IRAS 20126+4104, IRAS 21078+5211, IRAS 21307+5049, IRAS 22134+5834, IRAS 23011+6126, K3-50, W75N, and Mrk 231. One additional source, Arp 220, was observed and used as our primary calibrator. Details of the overall BLAST05 calibration procedure are discussed here. The BLAST observations of each compact source are described, flux densities and spectral energy distributions are reported, and these are compared with previous measurements at other wavelengths. The 250, 350, and 500 μm BLAST data can provide useful constraints to the amplitude and slope of the submillimeter continuum, which in turn may be useful for the improved calibration of other submillimeter instruments.

  13. Assessing inter-sensor variability and sensible heat flux derivation accuracy for a large aperture scintillometer.

    PubMed

    Rambikur, Evan H; Chávez, José L

    2014-01-27

    The accuracy in determining sensible heat flux (H) of three Kipp and Zonen large aperture scintillometers (LAS) was evaluated with reference to an eddy covariance (EC) system over relatively flat and uniform grassland near Timpas (CO, USA). Other tests have revealed inherent variability between Kipp and Zonen LAS units and bias to overestimate H. Average H fluxes were compared between LAS units and between LAS and EC. Despite good correlation, inter-LAS biases in H were found between 6% and 13% in terms of the linear regression slope. Physical misalignment was observed to result in increased scatter and bias between H solutions of a well-aligned and poorly-aligned LAS unit. Comparison of LAS and EC H showed little bias for one LAS unit, while the other two units overestimated EC H by more than 10%. A detector alignment issue may have caused the inter-LAS variability, supported by the observation in this study of differing power requirements between LAS units. It is possible that the LAS physical misalignment may have caused edge-of-beam signal noise as well as vulnerability to signal noise from wind-induced vibrations, both having an impact on the solution of H. In addition, there were some uncertainties in the solutions of H from the LAS and EC instruments, including lack of energy balance closure with the EC unit. However, the results obtained do not show clear evidence of inherent bias for the Kipp and Zonen LAS to overestimate H as found in other studies.

  14. APERTURE: a precise extremely large reflective telescope using re-configurable elements

    NASA Astrophysics Data System (ADS)

    Ulmer, M. P.; Coverstone, V. L.; Cao, J.; Chung, Y.-W.; Corbineau, M.-C.; Case, A.; Murchison, B.; Lorenz, C.; Luo, G.; Pekosh, J.; Sepulveda, J.; Schneider, A.; Yan, X.; Ye, S.

    2016-07-01

    One of the pressing needs for the UV-Vis is a design to allow even larger mirrors than the JWST primary at an affordable cost. We report here the results of a NASA Innovative Advanced Concepts phase 1 study. Our project is called A Precise Extremely large Reflective Telescope Using Reconfigurable Elements (APERTURE). The idea is to deploy a continuous membrane-like mirror. The mirror figure will be corrected after deployment to bring it into better or equal lambda/20 deviations from the prescribed mirror shape. The basic concept is not new. What is new is to use a different approach from the classical piezoelectric-patch technology. Instead, our concept is based on a contiguous coating of a so called magnetic smart material (MSM). After deployment a magnetic write head will move on the non-reflecting side of the mirror and will generate a magnetic field that will produce a stress in the MSM that will correct the mirror deviations from the prescribed shape.

  15. Tracking marine mammals and ships with small and large-aperture hydrophone arrays

    NASA Astrophysics Data System (ADS)

    Gassmann, Martin

    Techniques for passive acoustic tracking in all three spatial dimensions of marine mammals and ships were developed for long-term acoustic datasets recorded continuously over months using custom-designed arrays of underwater microphones (hydrophones) with spacing ranging from meters to kilometers. From the three-dimensional tracks, the acoustical properties of toothed whales and ships, such as sound intensity and directionality, were estimated as they are needed for the passive acoustic abundance estimation of toothed whales and for a quantitative description of the contribution of ships to the underwater soundscape. In addition, the tracks of the toothed whales reveal their underwater movements and demonstrate the potential of the developed tracking techniques to investigate their natural behavior and responses to sound generated by human activity, such as from ships or military SONAR. To track the periodically emitted echolocation sounds of toothed whales in an acoustically refractive environment in the upper ocean, a propagation-model based technique was developed for a hydrophone array consisting of one vertical and two L-shaped subarrays deployed from the floating instrument platform R/P FLIP. The technique is illustrated by tracking a group of five shallow-diving killer whales showing coordinated behavior. The challenge of tracking the highly directional echolocation sounds of deep-diving (< 1 km) toothed whales, in particular Cuvier's beaked whales, was addressed by embedding volumetric small-aperture (≈ 1 m element spacing) arrays into a large-aperture (≈ 1 km element spacing) seafloor array to reduce the minimum number of required receivers from five to two. The capabilities of this technique are illustrated by tracking several groups of up to three individuals over time periods from 10 min to 33 min within an area of 20 km2 in the Southern California Bight. To track and measure the underwater radiated sound of ships, a frequency domain beamformer was

  16. Design and performance of coded aperture optical elements for the CESR-TA x-ray beam size monitor

    NASA Astrophysics Data System (ADS)

    Alexander, J. P.; Chatterjee, A.; Conolly, C.; Edwards, E.; Ehrlichman, M. P.; Flanagan, J. W.; Fontes, E.; Heltsley, B. K.; Lyndaker, A.; Peterson, D. P.; Rider, N. T.; Rubin, D. L.; Seeley, R.; Shanks, J.

    2014-12-01

    We describe the design and performance of optical elements for an x-ray beam size monitor (xBSM), a device measuring e+ and e- beam sizes in the CESR-TA storage ring. The device can measure vertical beam sizes of 10 - 100 μm on a turn-by-turn, bunch-by-bunch basis at e± beam energies of ~ 2 - 5 GeV. x-rays produced by a hard-bend magnet pass through a single- or multiple-slit (coded aperture) optical element onto a detector. The coded aperture slit pattern and thickness of masking material forming that pattern can both be tuned for optimal resolving power. We describe several such optical elements and show how well predictions of simple models track measured performances.

  17. BLAST-TNG: A Next Generation Balloon-borne Large Aperture Submillimeter Polarimeter

    NASA Astrophysics Data System (ADS)

    Fissel, Laura M.; Ade, Peter; Angilè, Francesco E.; Campbell Ashton, Peter; Austermann, Jason Edward; Billings, Tashalee; Che, George; Cho, Hsiao-Mei; Cunningham, Maria R.; Davis, Kristina; Devlin, Mark J.; Dicker, Simon; Dober, Bradley; Fukui, Yasuo; Galitzki, Nicholas; gao, jiansong; Gordon, Sam; Groppi, Christopher E.; Hillbrand, Seth; Hilton, Gene; Hubmayr, Hannes; Irwin, Kent; Jones, Paul; Klein, Jeffrey; li, dale; Li, Zhi-Yun; lourie, nathan; Lowe, Ian; Mani, Hamdi; Martin, Peter G.; Mauskopf, Philip; McKenney, Christopher; Nati, Federico; Novak, Giles; Pascale, Enzo; pisano, giampaolo; Pereira Santos, Fábio; Scott, Douglas; Sinclair, Adrian; Diego Diego Soler, Juan; tucker, carole; Underhill, Matthew; Vissers, Michael; Williams, Paul

    2017-01-01

    Measurements of polarized thermal dust emission can be used to map magnetic fields in the interstellar medium. Recently, BLASTPol, the Balloon-borne Large Aperture Submillimeter Telescope for Polarimetry, has published the most detailed map ever made of a giant molecular cloud forming high-mass stars. I will present an overview of The Next Generation BLAST polarimeter (BLAST-TNG), the successor telescope to BLASTPol, which maps linearly polarized dust emission at 250, 350 and 500 μm. BLAST-TNG utilizes a 2.5-meter carbon-fiber primary mirror that illuminates focal plane arrays containing over 3,000 microwave kinetic inductance detectors. This new polarimeter has an order of magnitude increase in mapping speed and resolution compared to BLASTPol and we expect to make over 500,000 measurements of magnetic field orientation per flight. BLAST-TNG will have the sensitivity to map entire molecular cloud complexes as well as regions of diffuse high Galactic latitude dust. It also has the resolution (FWHM = 25’’ at 250 μm) necessary to trace magnetic fields in prestellar cores and dense filaments. BLAST-TNG will thus provide a crucial link between the low resolution Planck all-sky maps and the detailed but narrow field of view polarimetry capabilities of ALMA. For our first Antarctic flight in December 2017 we are putting out a call for shared-risk proposals to fill 25% of the available science time. In addition, BLAST-TNG data will be publicly released within a year of the publication of our first look papers, leaving a large legacy data set for the study of the role played by magnetic fields in the star formation process and the properties of interstellar dust.

  18. Imaging the midcontinent rift beneath Lake Superior using large aperture seismic data

    USGS Publications Warehouse

    Trehu, Anne M.; Morel-a-l'Huissier, Patrick; Meyer, R.; Hajnal, Z.; Karl, J.; Mereu, R. F.; Sexton, J.; Shay, J.; Chan, W. K.; Epili, D.; Jefferson, T.; Shih, X. R.; Wendling, S.; Milkereit, B.; Green, A.; Hutchinson, Deborah R.

    1991-01-01

    We present a detailed velocity model across the 1.1 billion year old Midcontinent Rift System (MRS) in central Lake Superior. The model was derived primarily from onshore-offshore large-aperture seismic and gravity data. High velocities obtained within a highly reflective half-graben that was imaged on coincident seismic reflection data demonstrate the dominantly mafic composition of the graben fill and constrain its total thickness to be at least 30km. Strong wide-angle reflections are observed from the lower crust and Moho, indicating that the crust is thickest (55–60km) beneath the axis of the graben. The total crustal thickness decreases rapidly to about 40 km beneath the south shore of the lake and decreases more gradually to the north. Above the Moho is a high-velocity lower crust interpreted to result from syn-rift basaltic intrusion into and/or underplating beneath the Archean lower crust. The lower crust is thickest beneath the axis of the main rift half-graben. A second region of thick lower crust is found approximately 100km north of the axis of the rift beneath a smaller half graben that is interpreted to reflect an earlier stage of rifting. The crustal model presented here resembles recent models of some passive continental margins and is in marked contrast to many models of both active and extinct Phanerozoic continental rift zones. It demonstrates that the Moho is a dynamic feature, since the pre-rift Moho is probably within or above the high-velocity lower crust, whereas the post-rift Moho is defined as the base of this layer. In the absence of major tectonic activity, however, the Moho is very stable, since the large, abrupt variations in crustal thickness beneath the MRS have been preserved for at least a billion years.

  19. Large-scale and non-contact surface topography measurement using scanning ion conductance microscopy and sub-aperture stitching technique

    NASA Astrophysics Data System (ADS)

    Zhuang, Jian; Guo, Renfei; Li, Fei; Yu, Dehong

    2016-08-01

    In this paper, we propose a large-scale and non-contact surface topography measurement method using a non-contact scanning probe microscopy (SPM) technique, scanning ion conductance microscopy (SICM), combined with the sub-aperture stitching technique. The phase correlation techniques were first applied to the three-dimensional (3D) images measured by the SICM to acquire an initially coarse stitching position. Then the tip-tilt compensated sub-aperture stitching algorithm is utilized to eliminate tilts and translations among adjacent images and expand the lateral measuring range of the existing hopping mode SICM system. This SICM and the stitching based method has been used to measure some large-scale samples (micrometer to millimeter scale) in a non-contact, quantitative and high resolution way. Simulation and experimental results on these samples verify the feasibility of this method and the effectiveness of the stitching algorithm. A measuring range of 1.08 mm  ×  0.55 mm and a lateral resolution of 100 nm or even higher were obtained in these experiments. Compared with atomic force microscopy (AFM), the non-contact feature of the proposed method ensures less damage to the surface topography. The non-optical feature makes the data stitching simpler than the existing optical microscopic methods, which need consider how to compensate the vignetting effect caused by the inhomogeneity of light.

  20. Scaling multiconjugate adaptive optics performance estimates to extremely large telescopes

    NASA Astrophysics Data System (ADS)

    Ellerbroek, Brent L.; Rigaut, Francois J.

    2000-07-01

    Multi-conjugate adaptive optics (MCAO) is a key technology for extremely large, ground-based telescopes (ELT's) because it enables near-uniform atmospheric turbulence compensation over fields-of-view considerably larger than can be corrected with more conventional AO systems. Quantitative performance evaluation using detailed analytical or simulation models is difficult, however, due to the very large number of deformable mirror (DM) actuators, wave front sensors (WFS) subapertures, and guide stars which might comprise an MCAO system for an ELT. This paper employs more restricted minimal variance estimation methods to evaluate the fundamental performance limits imposed by anisoplanatism alone upon MCAO performance for a range of sample cases. Each case is defined by a atmospheric turbulence profile, telescope aperture diameter, field-of-view, guide star constellation, and set of DM conjugate ranges. For a Kolmogorov turbulence spectrum with an infinite outer scale, MCAO performance for a whole range of aperture diameters and proportional fields-of-view can be computed at once using a scaling law analogous to the (D/dO)5/3 formula for the cone effect. For 30 meter telescopes, useful levels of performance are possible across a 1.0 - 2.0 arc minute square field-of-view using 5 laser guide stars (LGS's) and 3 DM's, and somewhat larger fields can be corrected using 9 guide stars and 4 mirrors. 3 or more tip/tilt natural guide stars (NGS's) are necessary to detect modes of tilt anisoplanatism which cannot be detected using LGS's, however. LGS MCAO performance is a quite weak function of aperture diameter for a fixed field-of-view, and it is tempting to scale these results to larger apertures. NGS MCAO performance is moderately superior to LGS MCAO if the NGS constellation is within the compensated field-of-view, but degrades rapidly as the guide stars move away from the field. The penalty relaxes slowly with increasing aperture diameter, but how to extrapolate this trend

  1. Stylus profilometry of large optics

    NASA Astrophysics Data System (ADS)

    Wills-Moren, William J.; Leadbeater, Peter B.

    1990-11-01

    This paper indicates the emerging requirements for profilometry instruments for use in the fabrication and characterization of modern optical systems. Important design principles are covered, together with some of the problems which can be experienced. Examples of a number of systems recently developed are given - both stand-alone systems and those which operate in situ to the machining process.

  2. Determining suitability of Large Aperture Scintillometer for validating remote sensing based evapotranspiration maps

    NASA Astrophysics Data System (ADS)

    Paul, G.; Gowda, P. H.; Howell, T. A.; Basu, S.; Colaizzi, P. D.; Marek, T.

    2013-12-01

    Scintillation method is a relatively new technique for measuring the sensible heat and water fluxes over land surfaces. Path integrating capabilities of scintillometer over heterogeneous landscapes make it a potential tool for comparing the energy fluxes derived from remote sensing based energy balance algorithms. For this reason, scintillometer-derived evapotranspiration (ET) fluxes are being used to evaluate remote sensing based energy balance algorithms for their ability to estimate ET fluxes. However, LAS' (Large Aperture Scintillometer) ability to derive ET fluxes is not thoroughly tested. The objective of this study was to evaluate LAS- and Surface Energy Balance System (SEBS)-derived fluxes against lysimetric data to determine LAS' suitability for validating remote sensing based evapotranspiration (ET) maps. The study was conducted during the Bushland Evapotranspiration and Agricultural Remote sensing EXperiment - 2008 (BEAREX-08) at the USDA-ARS Conservation and Production Research Laboratory (CPRL), Bushland, Texas. SEBS was coded in a GIS environment to retrieve ET fluxes from the high resolution imageries acquired using airborne multispectral sensors. The CPRL has four large weighing lysimeters (3 m long x 3 m wide x 2.4 m deep), each located in the middle of approximately 5 ha fields, arranged in a block pattern. The two lysimeter fields located on the east (NE and SE) were managed under irrigated conditions, and the other two lysimeters on the west (NW and SW) were under dryland management. Each lysimeter field was equipped with an automated weather station that provided measurements for net radiation (Rn), Ts, soil heat flux (Go), Ta, relative humidity, and wind speed. During BEAREX08, the NE and SE fields were planted to cotton on May 21, and the NW and SW dryland lysimeters fields were planted to cotton on June 5. One LAS each was deployed across two large dryland lysimeter fields (NW and SW) and two large irrigated lysimeter fields (NE and SE). The

  3. Assessment of large aperture scintillometry for large-area surface energy fluxes over an irrigated cropland in north India

    NASA Astrophysics Data System (ADS)

    Danodia, Abhishek; Sehgal, V. K.; Patel, N. R.; Dhakar, R.; Mukherjee, J.; Saha, S. K.; Kumar, A. Senthil

    2017-07-01

    Amount of available net energy and its partitioning into sensible, latent and soil heat fluxes over an agricultural landscape are critical to improve estimation of evapotranspiration and modelling parse (ecosystem modelling, hydrological and meteorological modelling). Scintillometry is a peculiar and robust methodology to provide structure parameter of refractive index and energy balance. Scintillometer has proven for assessment of sensible and latent heat flux, which is based on the principle of Monin-Obukhov similarity theory. Scintillometer has been installed in the agricultural experimental farm of ICAR-Indian Agricultural Research Institute, New Delhi, with a spatial covering path length of 990 m of irrigated and cultivable agricultural landscape. This paper discusses the patterns of energy flux as diurnal and seasonal basis at scintillometer path which was mainly covered by maize in Kharif and wheat in Rabi season during a crop growing seasons of 2014-2015. The biophysical parameters (leaf area, soil moisture, crop height) were recorded at a temporal resolution of fortnight basis along the path length at usual sampling distance. The Bowen ratio value for both Kharif and Rabi season was 0.76 and 0.88, respectively by scintillometer. Leaf area index had a significantly positive correlation with latent heat flux (R2 =0.80) while a significantly negative correlation with sensible heat flux (R2{=}-0.79). Soil moisture had a significant negative correlation with sensible heat flux (R2{=}-0.68). The average evapotranspiration from crop land was 1.58 mm d^{-1} and total evapotranspiration was 543 mm over the 12 months study period. This study defines that large aperture scintillometer is robust instrument which can evaluate energy flux over a large area with a long term series time domain. Moreover, further studied should be conducted to use in crop simulation modelling, developing of new model with calibration and validation of remote sensing energy balance

  4. Thermal performance assessment of a large aperture concentrating collector in an industrial application in Chile

    NASA Astrophysics Data System (ADS)

    Murray, Clare; Pino, Alan; Cardemil, José Miguel; Escobar, Rodrigo

    2017-06-01

    The application of solar thermal energy to meet the heat demands of the food and beverage processing industry in Chile has huge potential. This paper presents an assessment of the first large aperture trough collector installed in Latin America. The collector preheats water for a boiler in a juice-concentrating factory, 100 km north of Santiago. An analysis of the system for a day in November indicates the system was not able to utilize the heat generated, resulting in rapid de- and refocusing of the collector and problems with sensor calibration. An analysis of a day in March indicates the tracking algorithm has not correctly aligned the collector with the sun's position. An investigation into the design document reveals that the meteorological data underestimates the actual irradiation values by 40%, resulting in an oversized system given the actual conditions. To increase the energy gain in the system it is proposed to increase the working pressure from the current value of 1.5bar to up to 5bar, which could increase the system utilization from 41% to 65% and reduce the dumped energy to near zero. The simulation results with actual weather data and a fixed inlet temperature indicate the annual solar fraction could increase from the design value of 8.1% to 31.8% with a working pressure of 5 bar. The plant presents multiple opportunities for improvement not only to the performance of the plant but also in the design and installation of solar thermal systems in Chile in the future.

  5. All-reflective optical target illumination system with high numerical aperture

    DOEpatents

    Sigler, Robert D.

    1978-01-01

    An all-reflective optical system for providing illumination of a target focal region at high numerical aperture from a pair of co-axially, confluent collimated light beams. A target cavity is defined by a pair of opposed inner ellipsoidal reflectors having respective first focal points within a target region and second focal points at a vertex opening in the opposing reflector. Outwardly of each inner reflector is the opposed combination of a spherical reflector, and an outer generally ellipsoidal reflector having an aberrated first focal point coincident with the focus of the opposing spherical reflector and a second focal point coincident with the second focal point of the opposing inner ellipsoidal reflector through a vertex opening in the spherical reflector. The confluent collimated beams are incident through vertex openings in the outer ellipsoidal reflectors onto respective opposing spherical reflectors. Each beam is reflected by the associated spherical reflector onto the opposing outer ellipsoidal reflector and focused thereby onto the opposing inner ellipsoidal reflector, and then onto the target region.

  6. Large stable aluminum optics for aerospace applications

    NASA Astrophysics Data System (ADS)

    Vukobratovich, Daniel; Schaefer, John P.

    2011-09-01

    Aluminum mirrors offer the advantages of lower cost, shorter fabrication time, more rugged mounting, and same material athermalization when compared to classical glass mirrors. In the past these advantages were offset by controversial dimensional stability and high surface scatter, limiting applications to IR systems. Raytheon developed processes to improve long term stability, and reduce surface scatter. Six 380 mm aperture aluminum mirrors made using these processes showed excellent stability, with figure changes of less than 0.01 wave RMS(1 wave = 633 nm) when cycled 10 times between -51 and +71 deg. C. The VQ process developed at ELCAN reduces surface scatter in bare aluminum mirrors to below 20 angstroms RMS, and has been used in thousands of production mirrors up to 300 mm aperture. These processes were employed in the fabrication of two lightweight single arch 600 mm aluminum mirrors. The two mirrors were produced in four months, with a mounted surface figure of 0.22 waves RMS and surface roughness of 20 angstroms. Mounted fundamental frequency was 218 Hz, and no figure distortion was observed at preload levels four times higher than design. Subsequently the mirrors performed well when subjected to severe environmental loadings in a Raytheon test system. This technology is being extended to ultra-lightweight sandwich mirrors, which are competitive with other material technologies used in advanced aerospace applications such as high-altitude UAV surveillance systems and satellite optics.

  7. A Large Aperture Lidar Observatory for Exploring the Interaction of Our Atmosphere with Space (Invited)

    NASA Astrophysics Data System (ADS)

    Thayer, J. P.; Gardner, C. S.; Swenson, G. R.

    2013-12-01

    The mesopause region has been the subject of intensive study during the past decade because it is recognized as a critical region connecting our sensible atmosphere to the near-space environment. Processes in this region include a host of wave dynamics, heat and constituent transport, turbulence, polar mesospheric cloud formation, and the influx of meteoric material. Moreover, the neutral gas properties above the mesopause from 100 - 200 km altitude are poorly characterized and are influenced by additional processes that include solar EUV absorption / ionization, eddy to molecular diffusion, neutral wind dynamo action, and geomagnetic activity. Thus, this altitude region is a complex confluence of space and atmosphere processes that ultimately determine its properties. Fundamentally these processes are operating in any planetary atmosphere and must be understood in order to advance understanding of habitability and sustainability of a planetary system. While observational and modeling capabilities are evolving, progress in characterizing neutral properties and related processes in the mesopause region and above has been inhibited because they cannot be observed in sufficient detail and at high enough altitudes with existing instrumentation. This is especially true of the neutral atmosphere from 50 - 1000 km, where observations of its properties, dynamics and thermal structure are either sparse or nonexistent. A Large-Aperture Lidar Observatory (LALO) would enable significant progress by providing critical measurements of atmospheric constituents and parameters at greatly enhanced resolution and at much higher altitudes than is possible today. A large telescope in combination with modern high-power lasers, would enable observations of the neutral atmosphere to 1000 km altitude with a sensitivity and resolution approximately 1000 times better than can be achieved with the most powerful lidar systems in operation today. There are no technology barriers to realizing

  8. Convergent Polishing: A Simple, Rapid, Full Aperture Polishing Process of High Quality Optical Flats & Spheres

    PubMed Central

    Suratwala, Tayyab; Steele, Rusty; Feit, Michael; Dylla-Spears, Rebecca; Desjardin, Richard; Mason, Dan; Wong, Lana; Geraghty, Paul; Miller, Phil; Shen, Nan

    2014-01-01

    Convergent Polishing is a novel polishing system and method for finishing flat and spherical glass optics in which a workpiece, independent of its initial shape (i.e., surface figure), will converge to final surface figure with excellent surface quality under a fixed, unchanging set of polishing parameters in a single polishing iteration. In contrast, conventional full aperture polishing methods require multiple, often long, iterative cycles involving polishing, metrology and process changes to achieve the desired surface figure. The Convergent Polishing process is based on the concept of workpiece-lap height mismatch resulting in pressure differential that decreases with removal and results in the workpiece converging to the shape of the lap. The successful implementation of the Convergent Polishing process is a result of the combination of a number of technologies to remove all sources of non-uniform spatial material removal (except for workpiece-lap mismatch) for surface figure convergence and to reduce the number of rogue particles in the system for low scratch densities and low roughness. The Convergent Polishing process has been demonstrated for the fabrication of both flats and spheres of various shapes, sizes, and aspect ratios on various glass materials. The practical impact is that high quality optical components can be fabricated more rapidly, more repeatedly, with less metrology, and with less labor, resulting in lower unit costs. In this study, the Convergent Polishing protocol is specifically described for fabricating 26.5 cm square fused silica flats from a fine ground surface to a polished ~λ/2 surface figure after polishing 4 hr per surface on a 81 cm diameter polisher. PMID:25489745

  9. Towards a Network of Small Aperture Telescopes with Adaptive Optics Correction Capability

    NASA Astrophysics Data System (ADS)

    Cegarra Polo, M.; Lambert, A.

    2016-09-01

    A low cost and compact Adaptive Optics (AO) system for a small aperture telescope (Meade LX200ACF 16") has been developed at UNSW Canberra, where its performance is currently being evaluated. It is based on COTS components, with the exception of a real time control loop implemented in a Field Programmable Gate Array (FPGA), populated in a small form factor board which also includes the wavefront image sensor. A Graphical User Interface (GUI) running in an external computer connected to the FPGA imaging board provides the operator with control of different parameters of the AO system; results registration; and log of gradients, Zernike coefficients and deformable mirror voltages for later troubleshooting. The U.S. Air Force Academy Falcon Telescope Network (USAFA FTN) is an international network of moderate aperture telescopes (20 inches) that provides raw imagery to FTN partners [1]. The FTN supports general purpose use, including astronomy, satellite imaging and STEM (Science, Technology, Engineering and Mathematics) support. Currently 5 nodes are in operation, operated on-site or remotely, and more are to be commissioned over the next few years. One of the network nodes is located at UNSW Canberra (Australia), where the ground-based space surveillance team is currently using it for research in different areas of Space Situational Awareness (SSA). Some current and future SSA goals include geostationary satellite characterization through imaging modalities like polarimetry and real time image processing of Low Earth Orbit (LEO) objects. The fact that all FTN nodes have the same configuration facilitates the collaborative work between international teams of different nodes, so improvements and lessons learned at one site can be extended to the rest of nodes. With respect to this, preliminary studies of the imagery improvement that would be achieved with the AO system developed at UNSW, installed on a second 16 inch Meade LX200ACF telescope and compared to the

  10. Phase detection experiment for the down-looking synthetic aperture imaging ladar with electro-optic modulation

    NASA Astrophysics Data System (ADS)

    Lu, Zhiyong; Sun, Jianfeng; Zhi, Ya'nan; Zhang, Ning; Liu, Liren

    2014-09-01

    The down-looking synthetic aperture imaging ladar (SAIL) with electro-optic modulation was proposed. The measurement uses electrically controlled scanner to produce beams with spatial parabolic phase difference, which consists of electro-optic crystal and cylindrical lens. Due to the high modulation rate without mechanical scanning, this technique has a great potential for applications in extensive synthetic aperture imaging ladar fields. The phase mapping of electrically controlled scanner under the different applied voltage is achieved and measured by the polarized digital holographic interferometry. The phase mappings of the scanner in the down-looking SAIL with the o-polarized light and e-polarized light are obtained. The linear phase distribution and the parabolic phase distribution are observed after applying the external electric field. The corresponding analyses and discussions are proposed to explain the phenomena.

  11. Theoretical and Experimental Study of a Numerical Aperture for Multimode PCS Fiber Optics Using an Imaging Technique

    NASA Astrophysics Data System (ADS)

    Saman, Q. Mawlud; Nahlah, Q. Muhamad

    2012-11-01

    We study theoretically and experimentally the properties of numerical aperture (NA) of multimode graded-index plastic core silica (PCS) fibers by using an image technique. A He-Ne laser at wavelength 632.8 nm and output power 1 mW is used as the transmitter light source. The output beam images and intensity profiles of an optical fiber are investigated by using an imaging technique. The laser beam profiles captured by a sensitive digital Nikon camera are processed and analyzed by using a Gaussian intensity distribution in a 2D graph. A MathCAD 14 program is used for converting the image of the laser output beam into data. The theoretical and experimental values of the numerical aperture for the used optical fiber in this study are found to be 0.5 and 0.4924, respectively. The theoretical value of V-number is also calculated to be approximately 2482.

  12. Single Objective Lens Having Numerical Aperture of 0.85 for a High Density Optical Disk System

    NASA Astrophysics Data System (ADS)

    Itonaga, Makoto; Ito, Fumihiko; Matsuzaki, Kunihisa; Chaen, Shuichiro; Oishi, Kenji; Ueno, Tomonori; Nishizawa, Akira

    2002-03-01

    For the optical disk systems in the next generation, a GaN laser and a high numerical aperture lens are key components. This paper describes the first single objective lens that have the numerical aperture of 0.85. The lens form, which is the most important factor in realizing the lens, is analyzed. The measured wavefront aberration was 0.027λ which is was well below the diffraction limit of 0.07λ. The lens was installed in an optical pickup and write/read characteristics of the pickup with phase-change disks were investigated on a drive. Data-to-clock jitter of a read back signal was 9.5% of channel clock at a disk capacity of 25 Gbytes per 120-mm-diameter disk. The direct overwrite (DOW) characteristic was also measured. The jitter remained stable up to 1× 105 cycles. These results confirm the performance of the objective lens.

  13. Propagation properties of Hermite-cosine-Gaussian beams through a paraxial optical ABCD system with hard-edge aperture

    NASA Astrophysics Data System (ADS)

    Zhou, Nanrun; Zeng, Guihua

    2004-03-01

    Based on the generalized Huygens-Fresnel diffraction integral, a recurrence propagation equation of Hermite-cosine-Gaussian (HcoG) beams through a paraxial optical ABCD system with hard-edge aperture is derived, which permits us to obtain the analytical propagation expression for HcoG beams of any order. Furthermore, the closed-form propagation expressions for the Gaussian, Hermite-Gaussian, cosine (sine)-Gaussian, cosh (sinh) and cosine (sine) beams passing through a paraxial optical ABCD system with hard-edge aperture can be obtained by treating them as special cases of the analytical propagation expression for HcoG beams. The advantages of our analytical results are analyzed, and the applications are illustrated with numerical examples.

  14. Surface accuracy analysis and mathematical modeling of deployable large aperture elastic antenna reflectors

    NASA Astrophysics Data System (ADS)

    Coleman, Michael J.

    One class of deployable large aperture antenna consists of thin light-weight parabolic reflectors. A reflector of this type is a deployable structure that consists of an inflatable elastic membrane that is supported about its perimeter by a set of elastic tendons and is subjected to a constant hydrostatic pressure. A design may not hold the parabolic shape to within a desired tolerance due to an elastic deformation of the surface, particularly near the rim. We can compute the equilibrium configuration of the reflector system using an optimization-based solution procedure that calculates the total system energy and determines a configuration of minimum energy. Analysis of the equilibrium configuration reveals the behavior of the reflector shape under various loading conditions. The pressure, film strain energy, tendon strain energy, and gravitational energy are all considered in this analysis. The surface accuracy of the antenna reflector is measured by an RMS calculation while the reflector phase error component of the efficiency is determined by computing the power density at boresight. Our error computation methods are tailored for the faceted surface of our model and they are more accurate for this particular problem than the commonly applied Ruze Equation. Previous analytical work on parabolic antennas focused on axisymmetric geometries and loads. Symmetric equilibria are not assumed in our analysis. In addition, this dissertation contains two principle original findings: (1) the typical supporting tendon system tends to flatten a parabolic reflector near its edge. We find that surface accuracy can be significantly improved by fixing the edge of the inflated reflector to a rigid structure; (2) for large membranes assembled from flat sheets of thin material, we demonstrate that the surface accuracy of the resulting inflated membrane reflector can be improved by altering the cutting pattern of the flat components. Our findings demonstrate that the proper choice

  15. Surface Water Detection Using Fused Synthetic Aperture Radar, Airborne LiDAR and Optical Imagery

    NASA Astrophysics Data System (ADS)

    Braun, A.; Irwin, K.; Beaulne, D.; Fotopoulos, G.; Lougheed, S. C.

    2016-12-01

    Each remote sensing technique has its unique set of strengths and weaknesses, but by combining techniques the classification accuracy can be increased. The goal of this project is to underline the strengths and weaknesses of Synthetic Aperture Radar (SAR), LiDAR and optical imagery data and highlight the opportunities where integration of the three data types can increase the accuracy of identifying water in a principally natural landscape. The study area is located at the Queen's University Biological Station, Ontario, Canada. TerraSAR-X (TSX) data was acquired between April and July 2016, consisting of four single polarization (HH) staring spotlight mode backscatter intensity images. Grey-level thresholding is used to extract surface water bodies, before identifying and masking zones of radar shadow and layover by using LiDAR elevation models to estimate the canopy height and applying simple geometry algorithms. The airborne LiDAR survey was conducted in June 2014, resulting in a discrete return dataset with a density of 1 point/m2. Radiometric calibration to correct for range and incidence angle is applied, before classifying the points as water or land based on corrected intensity, elevation, roughness, and intensity density. Panchromatic and multispectral (4-band) imagery from Quickbird was collected in September 2005 at spatial resolutions of 0.6m and 2.5m respectively. Pixel-based classification is applied to identify and distinguish water bodies from land. A classification system which inputs SAR-, LiDAR- and optically-derived water presence models in raster formats is developed to exploit the strengths and weaknesses of each technique. The total percentage of water detected in the sample area for SAR backscatter, LiDAR intensity, and optical imagery was 27%, 19% and 18% respectively. The output matrix of the classification system indicates that in over 72% of the study area all three methods agree on the classification. Analysis was specifically targeted

  16. Lensless optical image processing based on two-dimensional Fresnel diffraction for synthetic-aperture imaging ladar.

    PubMed

    Sun, Zhiwei; Sun, Jianfeng; Hou, Peipei; Zhou, Yu; Xu, Qian; Zhang, Ning; Liu, Liren

    2015-02-01

    A principle scheme of a lensless optical processor for synthetic-aperture imaging ladar (SAIL) is proposed. The collected data from SAIL is initially digitally added with a quadratic phase in the range direction. These data are then uploaded on a liquid crystal spatial light modulator to modulate the incident light. The target image is obtained through two-dimensional (2D) free-space Fresnel diffraction. The imaging process is mathematically analyzed using a 2D data-collection equation of strip-mode side-looking SAIL. The design equation, imaging resolutions, and target-image compression ratios are presented. Based on this principle scheme, we construct an experimental optical SAIL processor and present the imaging result of data obtained from one SAIL demonstrator. The optical processor is found to exhibit the flexible property of digital processing, as well as the fast processing capability of optical means, because this optical processor is a lensless system.

  17. Optical design for the large balloon reflector

    NASA Astrophysics Data System (ADS)

    Cortes-Medellin, German; O'Dougherty, Stefan; Walker, Christopher; Goldsmith, Paul F.; Groppi, Chris; Smith, Steve; Bernasconi, Pietro

    2016-07-01

    We present the details of the optical design, corrector system, mechanical layout, tolerances, pointing requirements, and overall performance of the sub-millimeter wavelength Large Balloon Reflector telescope (LBR).

  18. Afocal three-mirror anastigmat with zigzag optical axis for widened field of view and enlarged aperture

    NASA Astrophysics Data System (ADS)

    Li, Qi; Han, Lin; Jin, Yangming; Shen, Weimin

    2016-10-01

    In order to improve the detection accuracy and range of new generation of Forward Looking Infra-Red (FLIR) system for distant targets, its optical system, which usually consists of a fore afocal telescope and rear imaging lenses, is required to has wide spectral range, large entrance pupil aperture, and wide field of view (FOV). In this paper, a new afocal Three-Mirror Anastigmat (TMA) with widened field of view and high demagnification is suggested. Its mechanical structure remains coaxial, but it has zigzag optical axis through properly and slightly decentering and tilting of the three mirrors to avoid its secondary obscuration due to the third mirror as FOV increase. Compared with conventional off-axis TMA, the suggested zigzag-axis TMA is compact, easy-alignment and low-cost. The design method and optimum result of the suggested afocal TMA is presented. Its initial structural parameters are determined with its first-order relationship and primary aberration theory. Slight and proper decentration and tilt of each mirror is leaded in optimization so that its coaxial mechanical structure is held but attainable FOV and demagnification are respectively as wide and as high as possible. As an example, a 5.5-demagnification zigzag-axis afocal TMA with a wavelength range, an entrance pupil diameter, and FOV respectively from 3μm to 12μm, of 320mm, and 2×3.2 degrees and with a real exit pupil, is designed. Its imaging quality is diffraction limited. It is suitable for fore afocal telescope of the so-called third generation FLIR.

  19. Origins of High-frequency Scattered Waves Near PKKP From Large Aperture Seismic Array Data

    NASA Astrophysics Data System (ADS)

    Earle, P. S.; Vidale, J. E.

    2001-05-01

    Observations of high--frequency ( ~1 Hz) teleseismic scattered waves provide constraints for modelling fine--scale ( ~10 km) core--mantle boundary (CMB) topography and fine--scale mantle heterogeneity. The majority of previous modelling relied on precursors to PKPdf, but here we present an underutilized data set that will aid future research into Earth's fine--scale structure: scattered waves in the vicinity of PKKP. The data set consists of slant stacks generated from Large Aperture Seismic Array (LASA) data from 36 earthquakes and 6 explosions in the range 30o to 129o. Although precursors to PKKP have been studied, we examine stacks in a larger time--distance window and find that waves previously associated with scattering along the PKKP raypath actually originate from near surface scattering of PKP to P (PKP.P). In addition to these near surface contributions, three types of waves scattered at the CMB or in the overlying mantle explain the observed slownesses and onset times, including: forward scattering of PKKP between its P and KKP legs (P.KKP and PKK.P), back scattering of PKKP between its PK and KP legs (PK.KP), and similarly back scattering of SKKP energy between its SK and KP legs (SK.KP). The LASA stacks show where and when these waves are detected and where they are contaminated by the surface--scattered P.PKP. In addition, the stacks image the scattered waves' amplitude and slowness variations with time. P.KKP waves are observed near 128o (just beyond the PKKP ``b'' caustic) and last ~100 s. Close to 113o, SK.KP waves rise above the noise ~100 s before onset time of the main SKKP arrival. Observations of PK.KP span 30o to 100o. However, at distances greater than 50o they suffer from P.PKP contamination. At distances less than 50o PK.KP last for ~300 s. This is ~150 s longer than the maximum ray-theoretical prediction for waves scattered at the CMB, indicating possible contributions from the overlying mantle.

  20. Optical band-stop filter and multi-wavelength channel selector with plasmonic complementary aperture embedded in double-ring resonator

    NASA Astrophysics Data System (ADS)

    Wei, Zhongchao; Zhang, Xiaomeng; Zhong, Nianfa; Tan, Xiaopei; Li, Xianping; Liu, Yuebo; Wang, Faqiang; Meng, Hongyun; Liang, Ruisheng

    2017-02-01

    A compact nanoscale wavelength band-stop filter with aperture embedded in double-ring resonator is proposed and numerically investigated by using Finite-Difference Time-Domain (FDTD) method. With a narrow aperture created between embedded double rings, the modes of the split-ring cavity can be modulated by the aperture in different manners when the parameters of the aperture are changed. Furthermore, the absorption peaks of resonator modes can be selectively inhibited by altering the positions of the aperture without changing outer size of the resonator. Based on above characteristics, a 1 × 2 multiple-contact channel selector is designed with a rotating aperture which can select the output waveguide. The proposed filter and selector have potential applications in highly integrated optical circuits.

  1. Characterizing the divergence properties of the laser diode beams propagation through collimator and aperture ABCD optical system

    NASA Astrophysics Data System (ADS)

    Reza Hedayati Rad, M.; Kashani, F. D.; Eftekhari, M. M.; Reza Mahzoun, M.

    2010-11-01

    The propagation properties of Gaussian laser beams through a complete optical path including free space and the optics of transmitter and receiver containing a collimator, an aperture and a lens is studied. Based on the Collins integral and using the second order moment method, analytical formulas for intensity distribution and Power In Bucket (PIB) along the propagation path are derived. The effects of initial beam divergence, collimator-source separation distance and beam width deviation on laser beams properties are investigated. Obtained results are confirmed and illustrated with numerical examples and resulted graphs.

  2. Initial Technology Assessment for the Large UV-Optical-Infrared (LUVOIR) Mission Concept Study

    NASA Technical Reports Server (NTRS)

    Bolcar, Matthew R.; Feinberg, Lee D.; France, Kevin; Rauscher, Bernard J.; Redding, David; Schiminovich, David

    2016-01-01

    The NASA Astrophysics Divisions 30-Year Roadmap prioritized a future large-aperture space telescope operating in the ultra-violet-optical-infrared wavelength regime. The Association of Universities for Research in Astronomy envisioned a similar observatory, the High Definition Space Telescope. And a multi-institution group also studied the Advanced Technology Large Aperture Space Telescope. In all three cases, a broad science case is outlined, combining general astrophysics with the search for bio-signatures via direct-imaging and spectroscopic characterization of habitable exo-planets. We present an initial technology assessment that enables such an observatory that is currently being studied for the 2020 Decadal Survey by the Large UV-Optical Infrared (LUVOIR) surveyor Science and Technology Definition Team. We present here the technology prioritization for the 2016 technology cycle and define the required technology capabilities and current state-of-the-art performance. Current, planned, and recommended technology development efforts are also reported.

  3. Large aperture at low cost three-dimensional time-of-flight range sensor using scanning micromirrors and synchronous detector switching.

    PubMed

    Bogatscher, Siegwart; Streck, Andreas; Fox, Maik; Meinzer, Sebastian; Heussner, Nico; Stork, Wilhelm

    2014-03-10

    In this article the problem of achieving fast scanning of a time-of-flight range sensor with a large optical receiver aperture at low system cost is targeted. The presented approach to solve this problem consists of a micromirror-based transmitter unit and a receiver unit consisting of a large aperture lens system with a small field of view and a detector array. A concept, which is called synchronous detector switching, is applied to the detector array. Thereby electronic steering of the small receiver field of view is possible. The overall approach is compared to alternative approaches, and the underlying concept of synchronous detector switching is demonstrated experimentally in an implementation of a three-dimensional time-of-flight range sensor. It is theoretically shown that the presented concept is potentially cheaper than the alternative approaches for applications with a field of view of less than 60×60°. After a discussion of the strengths and limitations of the approach, its effect on broader scientific issues is outlined.

  4. Characterizing polarized illumination in high numerical aperture optical lithography with phase shifting masks

    NASA Astrophysics Data System (ADS)

    McIntyre, Gregory Russell

    The primary objective of this dissertation is to develop the phase shifting mask (PSM) as a precision instrument to characterize effects in optical lithography related to the use of polarized partially coherent illumination. The intent is to provide an in-situ characterization technique to add to the lithographer's tool-kit to help enable the stable and repeatable mass production of integrated circuits with feature sizes approaching 1/6th the wavelength of light being used. A series of complex-valued mathematical functions have been derived from basic principles and recent advances in photomask fabrication technology have enabled their implementation with four-phase mask making. When located in the object plane of an imaging system, these test functions serve to engineer a wavefiront that interacts with one particular optical effect, creating a measurable signal in the image plane. In most cases, these test patterns leverage proximity effects to create a central image intensity and are theoretically the most sensitive to the desired effect. Five novel classes of test patterns have been developed for in-situ characterization. The first two classes, The Linear Phase Grating (LPG) and Linear Phase Ring (LPR), both serve to characterize illumination angular distribution and uniformity by creating signals dependent on illumination angular frequency. The third class consists of the Radial Phase Grating (RPG) and Proximity Effect Polarization Analyzers (PEPA), which each create a polarization-dependent signal by taking advantage of the image reversal of one polarization component at high numerical aperture (NA). PSM Polarimetry employs a series of these patterns to form a complete polarization characterization of any arbitrary illumination scheme. The fourth and fifth classes employ sub-resolution interferometric reference probes to coherently interact with proximity effect spillover from a surrounding pattern. They measure the effective phase and transmission of the

  5. Design and construction of a large aperture quadrupole electromagnet for ILSE

    SciTech Connect

    Fawley, W.M.; Vella, M.C.; Peters, C.; Stuart, M.; Faltens, A.

    1995-08-01

    We are currently constructing a prototype quadrupole electromagnet for the proposed Induction Linac Systems Experiment (ILSE) at LBNL. ILSE will address many physics and engineering issues relevant to the design of a heavy-ion fusion driver accelerator. The pulsed electromagnet has two layers of current windings and will produce a field gradient of 28 T/m, wi a usable aperture of 6 cm. It operates at a repetition rate of 1 Hz, steady-state. In this paper, we discuss how the interaction of various concerns such as maximum dynamic aperture, short lattice period, field quality, iron yoke weight, heat transfer, and voltage standoff have led to our particular design choices. We also present 2- and 3-D numerical calculations concerning field topography and the results of transport simulations of space-charge dominated ion beams with ILSE parameters.

  6. Effect of Internal Aperture Variability on Tracer Transport in Large Discrete Fracture Networks (DFN)

    NASA Astrophysics Data System (ADS)

    Makedonska, N.; Painter, S. L.; Hyman, J.; Karra, S.; Gable, C. W.; Viswanathan, H. S.

    2015-12-01

    Aperture variability within individual fractures is usually neglected in modeling flow and transport through fractured media. Typically, individual fractures are assumed to be homogeneous. However, in reality, individual fractures are heterogeneous, which may affect flow and transport in fractured media. The relative importance of including in-fracture variability in flow and transport modeling has been under debate for a long time. Previous studies have shown flow channeling on an individual fracture with internal variability, where the fracture is considered isolated from the rest of the fracture network. Although these studies yield some clear insights into the process, the boundary conditions are impractical for field-scale networks, where the realistic boundary conditions are determined by fracture connections in the network. Therefore, flow in a single fracture is controlled not only by in-fracture variability but also by boundary conditions. In order to address the question of the importance of in-fracture variability, the internal heterogeneity of every individual fracture is incorporated into a three-dimensional fracture network, represented by a composition of intersecting fractures. The new DFN simulation capability, dfnWorks, is used to generate a kilometer scale DFNs similar to the Forsmark, Sweden site. In our DFN model, the in-fracture aperture variability is scattered over each cell of the computational mesh along the fracture, representing by a stationary Gaussian random field with various correlation lengths. The Lagrangian particle tracking is conducted in multiple DFN realizations and the flow-dependent Lagrangian parameters, non-reacting travel time, τ, and cumulative reactivity parameter, β, are obtained along particles streamlines. It is shown that early particle travel times are more sensitive to in-fracture aperture variability than tails of travel time distributions, where no significant effect of the aperture variations and spatial

  7. Optimization of Deposition Uniformity for Large Aperture NIF Substrates in a Planetary Rotation System

    SciTech Connect

    Oliver, J.B.; Talbot, D.

    2003-05-06

    Multilayer coatings on large substrates with increasingly complex spectral requirements are essential for a number of optical systems, placing stringent requirements on the error tolerances of individual layers. Each layer must be deposited quite uniformly over the entire substrate surface since any nonuniformity will add to the layer-thickness error level achieved. A deposition system containing a planetary rotation system with stationary uniformity masking is modeled, with refinements of the planetary gearing, source placement, and uniformity mask shape being utilized to achieve an optimal configuration. The impact of improper planetary gearing is demonstrated theoretically, as well as experimentally, providing more comprehensive requirements than simply avoiding repetition of previous paths through the vapor plume, until all possible combinations of gear teeth have been used. Deposition efficiency and the impact on the uniformity achieved are used to validate improved source placement.

  8. A 16-m Telescope for the Advanced Technology Large Aperture Telescope (ATLAST) Mission

    NASA Astrophysics Data System (ADS)

    Lillie, Charles F.; Dailey, D. R.; Polidan, R. S.

    2010-01-01

    Future space observatories will require increasingly large telescopes to study the earliest stars and galaxies, as well as faint nearby objects. Technologies now under development will enable telescopes much larger than the 6.5-meter diameter James Webb Space Telescope (JWST) to be developed at comparable costs. Current segmented mirror and deployable optics technology enables the 6.5 meter JWST telescope to be folded for launch in the 5-meter diameter Ariane 5 payload fairing, and deployed autonomously after reaching orbit. Late in the next decade, when the Ares V Cargo Launch Vehicle payload fairing becomes operational, even larger telescope can be placed in orbit. In this paper we present our concept for a 16-meter JWST derivative, chord-fold telescope which could be stowed in the 10-m diameter Ares V fairing, plus a description of the new technologies that enable ATLAST to be developed at an affordable price.

  9. A Large Sparse Aperture Densified Pupil Hypertelescope Concept for Ground Based Detection of Extra-Solar Earth-Like Planets

    NASA Technical Reports Server (NTRS)

    Gezari, D.; Lyon, R.; Woodruff, R.; Labeyrie, A.; Oegerle, William (Technical Monitor)

    2002-01-01

    A concept is presented for a large (10 - 30 meter) sparse aperture hyper telescope to image extrasolar earth-like planets from the ground in the presence of atmospheric seeing. The telescope achieves high dynamic range very close to bright stellar sources with good image quality using pupil densification techniques. Active correction of the perturbed wavefront is simplified by using 36 small flat mirrors arranged in a parabolic steerable array structure, eliminating the need for large delat lines and operating at near-infrared (1 - 3 Micron) wavelengths with flats comparable in size to the seeing cells.

  10. A Large Sparse Aperture Densified Pupil Hypertelescope Concept for Ground Based Detection of Extra-Solar Earth-Like Planets

    NASA Technical Reports Server (NTRS)

    Gezari, D.; Lyon, R.; Woodruff, R.; Labeyrie, A.; Oegerle, William (Technical Monitor)

    2002-01-01

    A concept is presented for a large (10 - 30 meter) sparse aperture hyper telescope to image extrasolar earth-like planets from the ground in the presence of atmospheric seeing. The telescope achieves high dynamic range very close to bright stellar sources with good image quality using pupil densification techniques. Active correction of the perturbed wavefront is simplified by using 36 small flat mirrors arranged in a parabolic steerable array structure, eliminating the need for large delat lines and operating at near-infrared (1 - 3 Micron) wavelengths with flats comparable in size to the seeing cells.

  11. World atlas of large optical telescopes

    NASA Technical Reports Server (NTRS)

    Meszaros, S. P.

    1979-01-01

    By 1980 there will be approximately 100 large optical telescopes in the world with mirror or lens diameters of one meter (39 inches) and larger. This atlas gives information on these telescopes and shows their locations on continent-sized maps. Observatory locations considered suitable for the construction of future large telescopes are also shown.

  12. Radius of Curvature Measurement of Large Optics Using Interferometry and Laser Tracker

    NASA Technical Reports Server (NTRS)

    Hagopian, John; Connelly, Joseph

    2011-01-01

    The determination of radius of curvature (ROC) of optics typically uses either a phase measuring interferometer on an adjustable stage to determine the position of the ROC and the optics surface under test. Alternatively, a spherometer or a profilometer are used for this measurement. The difficulty of this approach is that for large optics, translation of the interferometer or optic under test is problematic because of the distance of translation required and the mass of the optic. Profilometry and spherometry are alternative techniques that can work, but require a profilometer or a measurement of subapertures of the optic. The proposed approach allows a measurement of the optic figure simultaneous with the full aperture radius of curvature.

  13. What limits the achievable areal densities of large aperture space telescopes?

    NASA Astrophysics Data System (ADS)

    Peterson, Lee D.; Hinkle, Jason D.

    2005-08-01

    This paper examines requirements trades involving areal density for large space telescope mirrors. A segmented mirror architecture is used to define a quantitative example that leads to relevant insight about the trades. In this architecture, the mirror consists of segments of non-structural optical elements held in place by a structural truss that rests behind the segments. An analysis is presented of the driving design requirements for typical on-orbit loads and ground-test loads. It is shown that the driving on-orbit load would be the resonance of the lowest mode of the mirror by a reaction wheel static unbalance. The driving ground-test load would be dynamics due to ground-induced random vibration. Two general conclusions are derived from these results. First, the areal density that can be allocated to the segments depends on the depth allocated to the structure. More depth in the structure allows the allocation of more mass to the segments. This, however, leads to large structural depth that might be a significant development challenge. Second, the requirement for ground-test-ability results in an order of magnitude or more depth in the structure than is required by the on-orbit loads. This leads to the proposition that avoiding ground test as a driving requirement should be a fundamental technology on par with the provision of deployable depth. Both are important structural challenges for these future systems.

  14. Damage and fracture in large-aperture fused-silica vacuum spatial filter lenses

    NASA Astrophysics Data System (ADS)

    Campbell, John H.; Edwards, Gary J.; Marion, John E.

    1995-12-01

    Optical damage that results in large scale fracture has been observed in the large, high- fluence, fused-silica, spatial filter lenses on the Nova and Beamlet lasers. In nearly all cases damage occurs on the vacuum side of the lenses and because the vacuum side of the lens is under tensile stress this damage can lead to catastrophic crack growth if the flaw (damage) size exceeds the critical flaw size for SiO2. The damaged 52 cm Nova lenses fracture into two and sometimes three large pieces. Although under full vacuum load at the time they fracture, the Nova lenses do not implode. Rather we have observed that the pieces lock together and air slowly leaks into the vacuum spatial filter housing through the lens cracks. The Beamlet lenses have a larger aspect ratio and peak tensile stress than Nova. The peak tensile stress at the center of the output surface of the Beamlet lens is 1490 psi versus 810 psi for Nova. During a recent Beamlet high energy shot, a damage spot on the lens grew to the critical flaw size and the lens imploded. Post shot data indicate the lens probably fractured into 5 to 7 pieces, however, unlike Nova, these pieces did not lock together. Analysis shows that the likely source of damage is contamination from pinhole blow-off or out-gassing of volatile materials within the spatial filter. Contamination degrades the anti-reflection properties of the sol-gel coating and reduces its damage threshold. By changing the design of the Beamlet lens it may be possible to insure that it fails safe by locking up in much the same manner as the Nova lens.

  15. Autonomous Low Earth Orbit Satellite and Orbital Debris Tracking Using Mid Aperture COTS Optical Trackers

    NASA Astrophysics Data System (ADS)

    Ehrhorn, B.; Azari, D.

    Low Earth Orbit (LEO) and Orbital Debris tracking have become considerably important with regard to Space Situational Awareness (SSA). This paper discusses the capabilities of autonomous LEO and Orbital Debris Tracking Systems using commercially available (mid aperture 20-24 inch) telescopes, tracking gimbals, and CCD imagers. RC Optical Systems has been developing autonomous satellite trackers that allow for unattended acquisition, imaging, and orbital determination of LEOs using low cost COTS equipment. The test setup from which we are gathering data consists of an RC Optical Systems Professional Series Elevation over Azimuth Gimbal with field de-rotation, RC Optical Systems 20 inch Ritchey-Chretien Telescope coupled to an e2v CCD42-40 CCD array, and 77mm f/4 tracking lens coupled to a KAF-0402ME CCD array. Central to success of LEO acquisition and open loop tracking is accurate modeling of Gimbal and telescope misalignments and flexures. Using pro-TPoint and a simple automated mapping routine we have modeled our primary telescope to achieve pointing and tracking accuracies within a population standard deviation of 1.3 arc-sec (which is 1.1 arc-sec RMS). Once modeled, a mobile system can easily and quickly be calibrated to the sky using a simple 6-10 star map to solve for axis tilt and collimation coefficients. Acquisition of LEO satellites is accomplished through the use of a wide field imager. Using a 77mm f/4 lens and 765 x 510 x 9mu CCD array yields a 1.28 x 0.85 degree field of view in our test setup. Accurate boresite within the acquisition array is maintained throughout the full range of motion through differential tpoint modeling of the main and acquisition imagers. Satellite identification is accomplished by detecting a stationary centroid as a point source and differentiating from the background of streaked stars in a single frame. We found 100% detection rate of LEO with radar cross sections (RCS) of > 0.5 meter*meter within the acquisition array, and

  16. The Dobsonian telescope. A practical manual for building large aperture telescopes.

    NASA Astrophysics Data System (ADS)

    Kriege, D.; Berry, R.

    This book tells how you can build a state-of-the-art Dobsonian telescope using readily available materials and supplies. Every step of construction is detailed in photographs and diagrams, and the underlying ideas are carefully explained. As a result of a three-year collaboration between the authors, experienced and well-known telescope makers, one now has the opportunity to build a high-performance telescope with a 14-inch to 40-inch aperture based on the thoroughly tested designs described in this book.

  17. Processing method and process modeling of large aperture transparent magnesium aluminate spinel domes

    NASA Astrophysics Data System (ADS)

    Yu, Jian; McWilliams, Brandon; Kilczewski, Steven; Gilde, Gary; Lidie, Ashley; Sands, James

    2009-05-01

    Polycrystalline spinel serves as an alternative to materials such as sapphire and magnesium fluoride that are currently being used in electromagnetic window applications such as missile domes, where high strength, high hardness and high transmittance in the visible and infrared spectra are required. The cubic crystal lattice of spinel imparts an isotropy to the bulk optical property, which eliminates optical distortion due to birefringence that occurs in sapphire and other non-cubic materials. The current study is to find a reliable manufacturing process to produce large magnesium aluminate spinel domes from powder consolidation efficiently. A binder-less dry ball milling process was used to deflocculate the spinel powder to increase its fluidity in an effort to ease the shape-forming. Dry ball milling time trials were conducted at several intervals to determine the appropriate level of time required to break up both the hard and soft agglomerates associated with the virgin spinel powder. The common problems encountered in dry powder shape-forming are crack growth and delamination of the green body during cold isostatic pressing (CIPing). The cracking and the delamination are due to the buildup of stress gradients on the green body that are created by the frictional force between the powder and the die wall or mold wall. To understand the stresses during the CIPing process, a finite element analysis of stresses on the green body was conducted. The simulation was used to evaluate the effect of die tooling and process characteristics on the development of stress gradients in the green body dome. Additionally, the effect of friction between the die wall and powder was examined by the simulation. It was found that by mitigating the frictional forces, cracking and delamination on the green body could be eliminated. A stepped-pressure CIPing technique was developed to reduce stress gradient build-up during CIPing. Also, oleic acid lubricant was applied to the die wall to

  18. Near-Space TOPSAR Large-Scene Full-Aperture Imaging Scheme Based on Two-Step Processing.

    PubMed

    Zhang, Qianghui; Wu, Junjie; Li, Wenchao; Huang, Yulin; Yang, Jianyu; Yang, Haiguang

    2016-07-27

    Free of the constraints of orbit mechanisms, weather conditions and minimum antenna area, synthetic aperture radar (SAR) equipped on near-space platform is more suitable for sustained large-scene imaging compared with the spaceborne and airborne counterparts. Terrain observation by progressive scans (TOPS), which is a novel wide-swath imaging mode and allows the beam of SAR to scan along the azimuth, can reduce the time of echo acquisition for large scene. Thus, near-space TOPS-mode SAR (NS-TOPSAR) provides a new opportunity for sustained large-scene imaging. An efficient full-aperture imaging scheme for NS-TOPSAR is proposed in this paper. In this scheme, firstly, two-step processing (TSP) is adopted to eliminate the Doppler aliasing of the echo. Then, the data is focused in two-dimensional frequency domain (FD) based on Stolt interpolation. Finally, a modified TSP (MTSP) is performed to remove the azimuth aliasing. Simulations are presented to demonstrate the validity of the proposed imaging scheme for near-space large-scene imaging application.

  19. Near-Space TOPSAR Large-Scene Full-Aperture Imaging Scheme Based on Two-Step Processing

    PubMed Central

    Zhang, Qianghui; Wu, Junjie; Li, Wenchao; Huang, Yulin; Yang, Jianyu; Yang, Haiguang

    2016-01-01

    Free of the constraints of orbit mechanisms, weather conditions and minimum antenna area, synthetic aperture radar (SAR) equipped on near-space platform is more suitable for sustained large-scene imaging compared with the spaceborne and airborne counterparts. Terrain observation by progressive scans (TOPS), which is a novel wide-swath imaging mode and allows the beam of SAR to scan along the azimuth, can reduce the time of echo acquisition for large scene. Thus, near-space TOPS-mode SAR (NS-TOPSAR) provides a new opportunity for sustained large-scene imaging. An efficient full-aperture imaging scheme for NS-TOPSAR is proposed in this paper. In this scheme, firstly, two-step processing (TSP) is adopted to eliminate the Doppler aliasing of the echo. Then, the data is focused in two-dimensional frequency domain (FD) based on Stolt interpolation. Finally, a modified TSP (MTSP) is performed to remove the azimuth aliasing. Simulations are presented to demonstrate the validity of the proposed imaging scheme for near-space large-scene imaging application. PMID:27472341

  20. Rapid Adaptive Optical Recovery of Optimal Resolution over LargeVolumes

    PubMed Central

    Wang, Kai; Milkie, Dan; Saxena, Ankur; Engerer, Peter; Misgeld, Thomas; Bronner, Marianne E.; Mumm, Jeff; Betzig, Eric

    2014-01-01

    Using a de-scanned, laser-induced guide star and direct wavefront sensing, we demonstrate adaptive correction of complex optical aberrations at high numerical aperture and a 14 ms update rate. This permits us to compensate for the rapid spatial variation in aberration often encountered in biological specimens, and recover diffraction-limited imaging over large (> 240 μm)3 volumes. We applied this to image fine neuronal processes and subcellular dynamics within the zebrafish brain. PMID:24727653

  1. Large-field-of-view laser-scanning OR-PAM using a fibre optic sensor

    NASA Astrophysics Data System (ADS)

    Allen, T. J.; Zhang, E.; Beard, P. C.

    2015-03-01

    Laser-Scanning-Optical-Resolution Photoacoustic Microscopy (LSOR-PAM) requires an ultrasound detector with a low noise equivalent pressure (NEP) and a large angular detection aperture in order to image a large field of view (FOV). It is however challenging to meet these requirements when using piezoelectric receivers since using a small sensing element size (<100μm) in order to achieve a large angular detection aperture will inevitability reduce the sensitivity of the detector as it scales with decreasing element size. Fibre optic ultrasound sensors based on a Fabry Perot cavity do not suffer from this limitation and can provide high detection sensitivity (NEP<0.1kPa over a 20 MHz measurement bandwidth) with a large angular detection aperture due to their small active element size (~10μm). A LSOR-PAM system was developed and combined with this type of fibre optic ultrasound sensor. A set of phantom studies were undertaken. The first study demonstrated that a high resolution image over a large field of view (Ø11mm) could be obtained with a sampledetector separation of only 1.6mm. In the second study, a 12μm diameter tube filled with methylene blue whose absorption coefficient was similar to that of blood was visualised demonstrating that the fibre optic sensor could provide sufficient SNR for in-vivo microvascular OR-PAM imaging. These preliminary results suggest that the fibre optic sensor has the potential to outperform piezoelectric detectors for Laser-Scanning Optical Resolution Photoacoustic Microscopy (LSOR-PAM).

  2. Laboratory demonstration of a primary active mirror for space with the LATT: large aperture telescope technology

    NASA Astrophysics Data System (ADS)

    Briguglio, Runa; Biasi, Roberto; Gallieni, Daniele; Vettore, Christian; d'Amato, Francesco; Xompero, Marco; Arcidiacono, Carmelo; Lisi, Franco; Riccardi, Armando; Patauner, Christian; Lazzarini, Paolo; Tintori, Matteo; Duò, Fabrizio; Pucci, Mauro; Zuccaro Marchi, Alessandro; Maresi, Luca

    2016-07-01

    The LATT project is an ESA contract under TRP programme to demonstrate the scalability of the technology from ground-based adaptive mirrors to space active primary mirrors. A prototype spherical mirror based on a 40 cm diameter 1 mm thin glass shell with 19 contactless, voice-coil actuators and co-located position sensors have been manufactured and integrated into a final unit with an areal density lower than 20 kg/m2. Laboratory tests demonstrated the controllability with very low power budget and the survival of the fragile glass shell exposed to launch accelerations, thanks to an electrostatic locking mechanism; such achievements pushes the technology readiness level toward 5. With this prototype, the LATT project explored the feasibility of using an active and lightweight primary for space telescopes. The concept is attractive for large segmented telescopes, with surface active control to shape and co-phase them once in flight. In this paper we will describe the findings of the technological advances and the results of the environmental and optical tests.

  3. From Monolithics to Tethers to Freeflyers: The Spectrum of Large Aperture Sensing from Space

    NASA Technical Reports Server (NTRS)

    Leitner, Jesse; Quinn, David; Bauer, Frank (Technical Monitor)

    2002-01-01

    As part of NASA's endeavor to push the envelope and go where we have never been before, the Space Science Enterprise has laid out a vision which includes several missions that revolutionize the collection of scientific data from space. Many of the missions designed to meet the objectives of these programs depend heavily on the ability to perform space-based interferometry, which has recently become a rapidly growing field of investigation for both the scientific and engineering communities. While scientists are faced with the challenges of designing high fidelity optical systems capable of making detailed observations, engineers wrestle with the problem of providing s-pace-based platforms that can permit this data gathering to occur. Observational data gathering is desired at's variety of spectral wavelengths and resolutions, calling for interferometers with a range of baseline requirements. Approaches to configuration design are as varied as the missions themselves from large monolithic spacecraft to multiple free-flying small spacecraft and everything in between. As will be discussed, no one approach provides a 'panacea' of solutions rather each has its place in terms of the mission requirements. The purpose here is to identify the advantages and disadvantages of the various approaches, to discuss the driving factors in design selection and determine the relative range of applicability of each design approach.

  4. From monolithics to tethers to freeflyers: the spectrum of large aperture sensing from space

    NASA Astrophysics Data System (ADS)

    Leitner, Jesse; Quinn, Dave; Matsumura, Mark M.

    2003-02-01

    As part of The National Aeronautics and Space Administration's (NASA's) endeavor to push the envelope and go where we have never been before, the Space Science Enterprise has laid out a vision which includes several missions that revolutionize the collection of scientific data from space. Many of the missions designed to meet the objectives of these programs depend heavily on the ability to perform space-based interferometry, which has recently become a rapidly growing field of investigation for both the scientific and engineering communities. While scientists are faced with the challenges of designing high fidelity optical systems capable of making detailed observations, engineers wrestle with the problem of providing space-based platforms that can permit this data gathering to occur. Observational data gathering is desired at a variety of spectral wavelengths and resolutions, calling for interferometers with a range of baseline requirements. Approaches to configuration design are as varied as the missions themselves from large monolithic spacecraft to multiple free-flying small spacecraft and everything in between. As will be discussed, no one approach provides a ?panacea? of solutions rather each has its place in terms of the mission requirements. The purpose here is to identify the advantages and disadvantages of the various approaches, to discuss the driving factors in design selection and determine the relative range of applicability of each design approach.

  5. Aperture synthesis in space

    NASA Astrophysics Data System (ADS)

    Faucherre, Michel; Greenaway, A. H.; Merkle, F.; Noordam, J. E.; Perryman, M. A. C.

    1989-09-01

    The principles of optical aperture synthesis (OAS), which can yield images of much higher resolution than current ground observations, are essentially those of radio astronomy, and may be used in either space- or ground-based studies of the stellar envelopes around Be stars, the internal dynamics of active galaxies, etc. An account is presently given of possible OAS instrument configurations; it is shown that a large field of view can be achieved, so that the instrument may be calibrated on bright stars during the observation of faint sources. Mission concepts for a 'monostructure' OAS instrument of about 30-m size are examined.

  6. Earth Observation from a High Orbit: Pushing the Limits with Synthetic Aperture Optics

    DTIC Science & Technology

    2000-10-01

    lateral base homothecy =100 + complete (baseline+diameter) lateral homothecy Figure 2: Perspective view of a SAO instrument for _ 1000 + longitudinal... homothecy , Earth observation. + field curvature and distortion. 3 Aperture configuration This analysis has been applied to the EUCLID optimization RTP

  7. HI-CLASS on AEOS: a large-aperture laser radar for space surveillance/situational awareness investigations

    NASA Astrophysics Data System (ADS)

    Kovacs, Mark A.; Dryden, Gordon L.; Pohle, Richard H.; Ayers, Kirstie; Carreras, Richard A.; Crawford, Linda L.; Taft, Russell

    2001-12-01

    The Air Force Research Laboratory/Directed Energy Directorate (AFRL/DE) via the ALVA (Applications of Lidars for Vehicles with Analysis) program installed in late 2000 a wideband, 12 J 15 Hz CO2 laser radar (ladar) on the 3.67 meter aperture AEOS (Advanced Electro-Optics System) telescope. This system is part of the Maui Space Surveillance System (MSSS), on the summit of Haleakala, Maui, HI. This ladar adopts the technology successfully demonstrated by the first generation HI-CLASS (High Performance CO2) Ladar Surveillance Sensor) operating on the nearby 0.6 meter aperture Laser Beam Director (LBD) and developed under the Field Ladar Demonstration program, jointly sponsored by AFRL/DE and the Army's Space and Missile Defense Command. The moderate power (approximately 180 watts) HI-CLASS/AEOS system generates multiple, coherent waveforms for precision satellite tracking and characterization of space objects for 1 m2 targets at ranges out to 10,000 km. This system also will be used to track space objects smaller than30 cm at ranges to 2,000 km. A third application of this system is to provide data for developing satellite identification, characterization, health and status techniques. This paper will discuss the operating characteristics and innovative features of the new system. The paper will also review recent results in support of AF needs, demonstrations, experiments, as well as planned activities that directly support applications in the DoD, scientific, and commercial arenas.

  8. Intercomparison of flatness measurements of an optical flat at apertures of up to 150 mm in diameter

    NASA Astrophysics Data System (ADS)

    Quabis, S.; Schulz, M.; Ehret, G.; Asar, M.; Balling, P.; Křen, P.; Bergmans, R. H.; Küng, A.; Lassila, A.; Putland, D.; Williams, D.; Pirée, H.; Prieto, E.; Pérez, M.; Svedova, L.; Ramotowski, Z.; Vannoni, M.; Hungwe, F.; Kang, Y.

    2017-02-01

    Recently, a scientific comparison of flatness measuring instruments at European National Metrology Institutes (NMIs) was performed in the framework of EURAMET. The specimen was a well-polished optical surface with a maximum measurement aperture of 150 mm in diameter. Here, we present an evaluation concept, which allows the determination of a mean flatness map taking into account different lateral resolutions of the instruments and different orientations of the specimen during measurement. We found that all measurements are in agreement with the mean flatness map within the uncertainty intervals stated by the participants. The aim of this scientific comparison is to specify an appropriate operation and evaluation procedure for future comparisons.

  9. Use of scanning near-field optical microscope with an aperture probe for detection of luminescent nanodiamonds

    NASA Astrophysics Data System (ADS)

    Shershulin, V. A.; Samoylenko, S. R.; Shenderova, O. A.; Konov, V. I.; Vlasov, I. I.

    2017-02-01

    The suitability of scanning near-field optical microscopy (SNOM) to image photoluminescent diamond nanoparticles with nanoscale resolution is demonstrated. Isolated diamond nanocrystals with an average size of 100 nm, containing negatively charged nitrogen-vacancy (NV-) centers, were chosen as tested material. The NV- luminescence was stimulated by continuous 532 nm laser light. Sizes of analyzed crystallites were monitored by an atomic force microscope. The lateral resolution of the order of 100 nm was reached in SNOM imaging of diamond nanoparticles using 150 nm square aperture of the probe.

  10. Magnetorheological finishing and subaperture stitching interferometry of large and lightweight optics

    NASA Astrophysics Data System (ADS)

    Shorey, Aric B.; Kordonski, William; Tricard, Marc

    2004-09-01

    Significant challenges are faced in the manufacturing of the complex optics for the next generation of astronomical telescopes. Process improvements are required to establish cost effective techniques to finish the optics to the tight specification required in a timely manner. An added complication is realized when the optics are lightweight. The non-uniform support of the face-sheet in this case requires special efforts to avoid a print-through of the cell structure due to fabrication processes, gravity and/or cryogenic effects. Magnetorheological finishing (MRF) is a deterministic, sub-aperture polishing process that has been a revolutionary success in the fabrication of optics in the size range of 10-1000 mm. This production proven process is capable of polishing flats, spheres, aspheres and cylinders to a surface figure accuracy of better than 30 nm peak-to-valley (better than 5 nm rms), and microroughness better than 1 nm rms on a variety of glasses, glass ceramics and single crystal materials. Unique characteristics of MRF such as a high, stable removal rate, conformal nature of the sub-aperture tool and shear mode of material removal give it advantages in the finishing of large and lightweight optics. These qualities provide for a cost-effective process with a high rate of convergence that requires few iterations. Such a technology is ideally complemented by a system for the stitching of interferometric sub-aperture data. Stitching inherently enables the testing of larger apertures with higher resolution and, thanks to the built-in calibration, even to higher accuracy in many situations. While this approach enables the non-null testing of parts with greater aspheric departure and can lead to a significantly reduced non-common air path in the testing of long-radius concave parts, it is especially effective for convex optics. That is, stitching is particularly well suited to the testing of secondary mirrors and, alongside the testing of the off-axis primary

  11. Alternative Beam Efficiency Calculations for a Large-aperture Multiple-frequency Microwave Radiometer (LAMMR)

    NASA Technical Reports Server (NTRS)

    Schmidt, R. F.

    1979-01-01

    The fundamental definition of beam efficiency, given in terms of a far field radiation pattern, was used to develop alternative definitions which improve accuracy, reduce the amount of calculation required, and isolate the separate factors composing beam efficiency. Well-known definitions of aperture efficiency were introduced successively to simplify the denominator of the fundamental definition. The superposition of complex vector spillover and backscattered fields was examined, and beam efficiency analysis in terms of power patterns was carried out. An extension from single to dual reflector geometries was included. It is noted that the alternative definitions are advantageous in the mathematical simulation of a radiometer system, and are not intended for the measurements discipline where fields have merged and therefore lost their identity.

  12. Astrometric plates obtained at the primary focus of large aperture reflectors

    NASA Technical Reports Server (NTRS)

    Markos, A.

    1984-01-01

    Coma, astigmatism, and great differences in stellar magnitudes between photographed object and reference stars constitute the main sources of errors in measuring positional plates. These three sources of error can easily be eliminated by the method used at the Klet Observatory for obtaining precise observations of faint objects. The astrometric plates are taken by the method of two diaphragms. The first diaphragm, with a small central aperture; is located in front of the photographic plate. The second diaphragm is situated in front of the mirror. By a very short (of the order of tens of seconds) exposure a sufficient number of reference stars can be obtained throughout the entire plate. The stars are very well defined to the very edge of the plate and are easy to measure. Moreover, this method makes it possible to use plates of larger dimensions than usual so that it is always possible to find the necessary reference stars.

  13. Large-Aperture Deformable Mirror Correction of Tiled-Grating Wavefront Error

    SciTech Connect

    Kruschwitz, B.E.; Jungquist, R.; Qiao, J.; Abbey, S.; Dean, S.E.; Maywar, D.N.; Moore, M.D.; Waxer, L.J.; Wilson, M. E.

    2006-07-13

    When tiling three gratings, with each individually exhibiting astigmatism and power due to holographic errors and coating stress, the resulting wavefront aberrations contain high-frequency components as well as the fundamental frequency, which is nearly three cycles across the aperture in the tiling direction. A deformable mirror (DM) that was designed to compensate for much slower errors (e.g., those arising from distortion in amplifier disks) is being used to compensate for this tiling-induced error. This investigation studies the effectiveness of compensating only the fundamental frequency of the tiled aberration, and shows that this provides a significant improvement that is adequate for a range of expected aberrations. Limitations of the DM correction technique are also studied.

  14. Optical iconic filters for large class recognition.

    PubMed

    Casasent, D; Mahalamobis, A

    1987-06-01

    Approaches are advanced for pattern recognition when a large number of classes must be identified. Multilevel encoded multiple-iconic filters are considered for this problem. Hierarchical arrangements of iconic filters and/or preprocessing stages are described. A theoretical basis for the sidelobe level and noise effects of filters designed for large class problems is advanced. Experimental data are provided for an optical character recognition case study.

  15. Application of research for metal primary mirror of large-aperture infrared solar telescope

    NASA Astrophysics Data System (ADS)

    Meng, Xiaohui; Zhang, Haiying; Li, Xinnan

    2010-05-01

    Metal is an early telescope mirror material, it was later replaced by glass which has lower thermal expansion coefficient. However, for observing the sun, these glass materials in the primary mirror are affected by the sun's intense radiation, its temperature rises rapidly, but which conducts heat slowly. The temperature difference between mirror and ambient air is so large that causing the air turbulence which has affected the observation precision. While the metal material has better thermal conductivity characteristics, it can greatly improve the problems caused by air turbulence. This paper analyzes the characteristics of the various mirror materials, and then makes a rust-proof aluminum alloy 5A05 as the mirror substrate material. For the major deficiencies of the soft aluminum surface which is not suitable for polishing, this paper presents a method of electroless nickel plating to improve its surface properties. After the mirror go through a thermal shock, the upper and lower levels of metal CTE don't match with each other, which leads to mirror deformation and warping. The bimetallic effect has been illustrated by the theory of beam element and give a result of elementary approximated. The analysis shows that the displacement deformation of the upper and lower layers of metal which is caused by thermal shock is smaller when the CTE is closer. In the experiments, a spherical aluminum mirrors with the substrate of 5A05 aluminum alloy, diameter of 110mm, the radius of curvature of 258.672mm is manufactured in classical technique. And it ultimately achieves optical mirror-polished precision. Besides, the long-term thermal stability experimental study of the aluminum mirrors proved that Al-infrared solar telescope primary mirror meets the needs of the long-term observation during use.

  16. Feed System Design Considerations for Large Space Antenna Systems. Part 2: Single Aperture with Overlapping Feeds

    NASA Technical Reports Server (NTRS)

    Jamnejad, V.

    1985-01-01

    Contiguous multiple beams are used to make use of the set of frequency bands at different beams at different geographical locations and achieve the most efficient use of precious frequency allocation. This is feasible only if the interference among cochannel beams is below some acceptable level, by carrier/interference (C/I) ratio. Individual beam patterns of very low sidelobes, which in turn necessitates narrow feed are required. A physically realizable solution to this problem entails either more than one reflector, more complicated optics, or breaking of each feed into a cluster of smaller elements, some of which would then be shared by adjacent beams. The latter, however, requires a complicated beamforming network (BFN) for the proper feeding of the elements. The feedpacking problem is not unique to reflector antennas and exists in lens type antennas as well. The BFN and associated problems are present in the phased array antennas and on a much larger scale. Poor scan capabilities are associated with reflector systems. The scan properties of offset fed reflector systems can be improved by choosing a very large focal length to parent reflector diameter ((F/Dp) ratio, which requires a longer boom to support the feed. In the case of reflectors with cluster feed arrangements, the scan capability for smaller F/Dp ratios is improved by proper adjustment of cluster element excitations. Such a system seems to be appropriate for up to 10 beamwidths scan. For a larger number of beams, systems with wider scan capabilities, such as phased arrays or phased array/reflector combinations, become more appealing.

  17. Optically guided large-nanostructure probe

    NASA Astrophysics Data System (ADS)

    Marchman, Herschel M.; Wetsel, Grover C., Jr.

    1993-05-01

    A large-nanostructure probe with optically guided macroscopic scanning has been developed for high-resolution imaging and characterization of nanostructures. The novel optical viewing system allows placement of the imaging tip to within 1 μm of a desired site on the sample during coarse positioning. Fine positioning and imaging are accomplished with nanometer-scale resolution using a segmented-tube piezoelectric scanner. High-resolution images of identifiable quantum dots have been obtained to demonstrate the efficacy of the method.

  18. Optical 'magnetic mirror' metasurfaces using interference between Fabry-Pérot cavity resonances in coaxial apertures.

    PubMed

    Rajasekharan, Ranjith; Roberts, Ann

    2015-05-28

    Here we propose and computationally demonstrate a quasi-planar metasurface consisting of arrays of pairs of concentric coaxial apertures in a metallic film. The structure relies on destructive interference between Fabry-Pérot modes excited in each aperture at resonance producing transmitted fields that interfere destructively leading to suppressed transmission. Conversely, we show that in the case of a perfect conductor, near-perfect, broadband reflection can be achieved with zero phase change in the electric field and a variation of 2π on passing through the coincident resonances. Extending the concept to shorter wavelengths, we show that mirrors exhibiting close to a 2π phase excursion, albeit with a reduction in the amplitude reflection coefficient at resonance and a lower Q, can be also achieved. Structures such as these can be used to enhance light-matter interactions at surfaces and act as high impedance ground planes for antenna applications.

  19. The design, construction and testing of the optics for a 147-cm-aperture telescope

    NASA Technical Reports Server (NTRS)

    Buchroeder, R. A.; Elmore, L. H.; Shack, R. V.; Slater, P. N.

    1972-01-01

    Geodetic optics research for the Air Force Cambridge Research Laboratories (AFCRL) is described. The work consisted mainly of the fabrication of the optical components for a telescope with a 152-cm-diam (60-in.) primary mirror masked down to 147-cm-diam for use by the AFCRL for a lunar ranging experiment. Among the achievements of this contract were the following: completion of the primary and secondary mirrors for a high-quality 147-cm-diam telescope system in eight months from the start of edging the primary; manufacture and testing of a unique center mount for the primary according to an AFCRL design that allowed for a thin-edged and therefore less-massive mirror; and development of a quantitative analysis of the wire test for calculating the departure of the mirror figure from the design figure quickly and accurately after each polishing step. This analysis method in conjunction with a knowledge of polishing rates for given weights and diameters of tools, mirror, and polishing materials should considerably reduce the polishing time required for future large mirrors.

  20. Micro-precision control/structure interaction technology for large optical space systems

    NASA Technical Reports Server (NTRS)

    Sirlin, Samuel W.; Laskin, Robert A.

    1993-01-01

    The CSI program at JPL is chartered to develop the structures and control technology needed for sub-micron level stabilization of future optical space systems. The extreme dimensional stability required for such systems derives from the need to maintain the alignment and figure of critical optical elements to a small fraction (typically 1/20th to 1/50th) of the wavelength of detected radiation. The wavelength is about 0.5 micron for visible light and 0.1 micron for ultra-violet light. This lambda/50 requirement is common to a broad class of optical systems including filled aperture telescopes (with monolithic or segmented primary mirrors), sparse aperture telescopes, and optical interferometers. The challenge for CSI arises when such systems become large, with spatially distributed optical elements mounted on a lightweight, flexible structure. In order to better understand the requirements for micro-precision CSI technology, a representative future optical system was identified and developed as an analytical testbed for CSI concepts and approaches. An optical interferometer was selected as a stressing example of the relevant mission class. The system that emerged was termed the Focus Mission Interferometer (FMI). This paper will describe the multi-layer control architecture used to address the FMI's nanometer level stabilization requirements. In addition the paper will discuss on-going and planned experimental work aimed at demonstrating that multi-layer CSI can work in practice in the relevant performance regime.

  1. Engineering of optical modes in vertical-cavity microresonators by aperture placement: applications to single-mode and near-field lasers

    NASA Astrophysics Data System (ADS)

    Shchukin, V. A.; Ledentsov, N. N.; Kropp, J.-R.; Steinle, G.; Ledentsov, N. N.; Choquette, K. D.; Burger, S.; Schmidt, F.

    2015-03-01

    Oxide-confined vertical cavity surface emitting lasers (VCSEL) are inherently leaky structures, despite the fact that the oxidized periphery region surrounding the all-semiconductor core has a lower refractive index. The reason is that the VCSEL modes in the non-oxidized core region can be coupled to tilted modes in the selectively oxidized periphery as the orthogonality between the core mode and the modes at the periphery is broken by the oxidation-induced optical field redistribution. Engineered VCSEL designs show that the overlap between the VCSEL mode of the core and the tilted mode in the periphery can reach >30% resulting in significant leakage. Three-dimensional modeling confirms that the leakage losses are much stronger for high order transverse modes which have a higher field intensity close to the oxidized region. Single mode lasing in the fundamental mode can thus proceed up to large aperture diameters. A 850-nm GaAlAs leaky VCSEL based on this concept is designed, modeled and fabricated, showing single-mode lasing with aperture diameters up to 5 μm. Side mode suppression ratio >20dB is realized at the current density of 10kA/cm2 in devices with the series resistance of 90 Ω.

  2. A coherent light scanner for optical processing of large format transparencies

    NASA Technical Reports Server (NTRS)

    Callen, W. R.; Weaver, J. E.; Shackelford, R. G.; Walsh, J. R.

    1975-01-01

    A laser scanner is discussed in which the scanning beam is random-access addressable and perpendicular to the image input plane and the irradiance of the scanned beam is controlled so that a constant average irradiance is maintained after passage through the image plane. The scanner's optical system and design are described, and its performance is evaluated. It is noted that with this scanner, data in the form of large-format transparencies can be processed without the expense, space, maintenance, and precautions attendant to the operation of a high-power laser with large-aperture collimating optics. It is shown that the scanned format as well as the diameter of the scanning beam may be increased by simple design modifications and that higher scan rates can be achieved at the expense of resolution by employing acousto-optic deflectors with different relay optics.

  3. HYBRID BRIDGMAN ANVIL DESIGN: AN OPTICAL WINDOW FOR IN-SITU SPECTROSCOPY IN LARGE VOLUME PRESSES

    SciTech Connect

    Lipp, M J; Evans, W J; Yoo, C S

    2005-07-29

    The absence of in-situ optical probes for large volume presses often limits their application to high-pressure materials research. In this paper, we present a unique anvil/optical window-design for use in large volume presses, which consists of an inverted diamond anvil seated in a Bridgman type anvil. A small cylindrical aperture through the Bridgman anvil ending at the back of diamond anvil allows optical access to the sample chamber and permits direct optical spectroscopy measurements, such as ruby fluorescence (in-situ pressure) or Raman spectroscopy. This performance of this anvil-design has been demonstrated by loading KBr to a pressure of 14.5 GPa.

  4. A coherent light scanner for optical processing of large format transparencies

    NASA Technical Reports Server (NTRS)

    Callen, W. R.; Weaver, J. E.; Shackelford, R. G.; Walsh, J. R.

    1975-01-01

    A laser scanner is discussed in which the scanning beam is random-access addressable and perpendicular to the image input plane and the irradiance of the scanned beam is controlled so that a constant average irradiance is maintained after passage through the image plane. The scanner's optical system and design are described, and its performance is evaluated. It is noted that with this scanner, data in the form of large-format transparencies can be processed without the expense, space, maintenance, and precautions attendant to the operation of a high-power laser with large-aperture collimating optics. It is shown that the scanned format as well as the diameter of the scanning beam may be increased by simple design modifications and that higher scan rates can be achieved at the expense of resolution by employing acousto-optic deflectors with different relay optics.

  5. Large silicon carbide optics for manufacturability

    NASA Astrophysics Data System (ADS)

    Pepi, John W.; Robichaud, Joseph; Milsap, Gary

    2013-09-01

    For space-based use, projected needs are for large optics of the one-meter class that lie under 30 kg/m2 in mass areal density. Current space programs using glass optics, such as Kepler, exhibit a mass of 45 kg/m2, while JWST beryllium optics, including hardware attachment, are as low as 18 kg/m2. Silicon carbide optics can be made lighter than glass, although not as light as beryllium; however, distinct advantages in thermal conductivity and expansion coefficient are evidenced at all temperatures, allowing for greater thermal flux , minimizing gradients and maximizing performance, both earth and space looking. For manufacturability and production, it is desirable to minimize weight while maintaining reasonable cell spacing for open back lightweight design, which will reduce both cost and risk. To this end we perform a trade study to design such an optic that meets both mass and stiffness requirements while being within the regime of ease of manufacture. The design study chooses a hexagonal segment, 1.2 meters across flats (1.4 meters corner to corner), mimicking the JWST design. Polishing, mounting, test, and environmental operational errors are duly considered.

  6. Optical glasses and glass ceramics for large optical systems

    NASA Astrophysics Data System (ADS)

    Doehring, Thorsten; Hartmann, Peter; Morian, Hans F.; Jedamzik, Ralf

    2003-02-01

    Schott has delivered blanks for large lenses and prisms since many decades. Glass and glass ceramics objects with dimensions above 300 mm diameter or edge lengths will remain challenges for a glass manufacturer. This holds especially when the quality specifications exceed the standard level significantly. Optical glass blocks of more than half a ton have been produced with outstanding internal quality. Although the manufacturing process is well controlled there are restrictions on the availability of such objects (glass types, long process times e.g.). Implications of the glass production process are presented as a guideline for designers in order to avoid unnecessary time losses. The similarity of the production process of the glass ceramic ZERODUR to that of optical glasses results in high homogeneity with regard to the coefficient of thermal expansion as well as to the optical properties. This qualifies ZERODUR for even higher demanding applications especially when reproducibility in series production is required.

  7. Large aperture CCD x ray detector for protein crystallography using a fiberoptic taper

    NASA Astrophysics Data System (ADS)

    Strauss, M. G.; Westbrook, E. M.; Naday, I.; Coleman, T. A.; Westbrook, M. L.; Travis, D. J.; Sweet, R. M.; Pflugrath, J. W.

    A detector with a 114 mm aperture, based on a charge-coupled device (CCD), has been designed for x-ray diffraction studies in protein crystallography. The detector was tested on a beamline of the National Synchrotron Light Source at Brookhaven National Laboratory with a beam intensity greater than 10(exp 9) x-ray photons/s. A fiberoptic taper, an image intensifier and a lens demagnify, intensify, and focus the image onto a CCD having 512 x 512 pixels. A detective quantum efficiency (DOE) of 0.36 was obtained by evaluating the statistical uncertainty in the detector output. The dynamic range of a 4 x 4 pixel resolution element, comparable in size to a diffraction peak, was 10(exp 4). The point-spread function shows FWHM resolution of approximately 1 pixel, where a pixel on the detector face is 160 microns. A complete data set, consisting of forty-five 1 deg rotation frames, was obtained in just 36 s of x-ray exposure to a crystal of chicken egg-white lysozyme. In a separate experiment, a lysozyme data set consisting of 495 0.1 deg frames, was processed by the MADNES data reduction program, yielding symmetry R-factors for the data of 3.2 to 3.5 percent. Diffraction images from crystals of the myosin S1 head (a = 275 A) were also recorded. The Bragg spots, only 5 pixels apart, were resolved but were not sufficiently separated to process these data. Changes in the detector design which will improve the DOE and spatial resolution are outlined. The overall performance showed that this type of detector is well suited for x-ray scattering investigations with synchrotron sources.

  8. A 2x2 multi-chip reconfigurable MOEMS mask: a stepping stone to large format microshutter arrays for coded aperture applications

    NASA Astrophysics Data System (ADS)

    McNie, Mark E.; Brown, Alan G.; King, David O.; Smith, Gilbert W.; Gordon, Neil T.; Riches, Stephen; Rogers, Stanley

    2010-08-01

    Coded aperture imaging has been used for astronomical applications for several years. Typical implementations used a fixed mask pattern and are designed to operate in the X-Ray or gamma ray bands. Recently applications have emerged in the visible and infra red bands for low cost lens-less imaging systems and system studies have shown that considerable advantages in image resolution may accrue from the use of multiple different images of the same scene - requiring a reconfigurable mask. Previously reported work focused on realising a 2x2cm single chip mask in the mid-IR based on polysilicon micro-optoelectro- mechanical systems (MOEMS) technology and its integration with ASIC drive electronics using conventional wire bonding. It employs interference effects to modulate incident light - achieved by tuning a large array of asymmetric Fabry-Perot optical cavities via an applied voltage and uses a hysteretic row/column scheme for addressing. In this paper we report on the latest results in the mid-IR for the single chip reconfigurable MOEMS mask, trials in scaling up to a mask based on a 2x2 multi-chip array and report on progress towards realising a large format mask comprising 44 MOEMS chips. We also explore the potential of such large, transmissive IR spatial light modulator arrays for other applications and in the current and alternative architectures.

  9. Temporally focused femtosecond laser pulses for low numerical aperture micromachining through optically transparent materials.

    PubMed

    Vitek, Dawn N; Adams, Daniel E; Johnson, Adrea; Tsai, Philbert S; Backus, Sterling; Durfee, Charles G; Kleinfeld, David; Squier, Jeffrey A

    2010-08-16

    Temporal focusing of spatially chirped femtosecond laser pulses overcomes previous limitations for ablating high aspect ratio features with low numerical aperture (NA) beams. Simultaneous spatial and temporal focusing reduces nonlinear interactions, such as self-focusing, prior to the focal plane so that deep (approximately 1 mm) features with parallel sidewalls are ablated at high material removal rates (25 microm(3) per 80 microJ pulse) at 0.04-0.05 NA. This technique is applied to the fabrication of microfluidic devices by ablation through the back surface of thick (6 mm) fused silica substrates. It is also used to ablate bone under aqueous immersion to produce craniotomies.

  10. Broadband light funneling in ultrasubwavelength channels having periodic connected unfilled apertures

    DOEpatents

    Subramania, Ganapathi Subramanian; Brener, Igal; Foteinopoulou, Stavroula

    2017-08-01

    A structure for broadband light funneling comprises a two-dimensional periodic array of connected ultrasubwavelength apertures, each aperture comprising a large sub-aperture that aids in the coupling of the incoming incident light and a small sub-aperture that funnels a significant fraction of the incident light power. The structure possesses all the capabilities of prior extraordinary optical transmission platforms, yet operates nonresonantly on a distinctly different mechanism. The structure demonstrates efficient ultrabroadband funneling of optical power confined in an area as small as .about.(.lamda./500).sup.2, where optical fields are enhanced, thus exhibiting functional possibilities beyond resonant platforms.

  11. Design of compact surface optical coupler based on vertically curved silicon waveguide for high-numerical-aperture single-mode optical fiber

    NASA Astrophysics Data System (ADS)

    Atsumi, Yuki; Yoshida, Tomoya; Omoda, Emiko; Sakakibara, Youichi

    2017-09-01

    A surface optical coupler based on a vertically curved Si waveguide was designed for coupling with high-numerical aperture single-mode optical fibers with a mode-field diameter of 5 µm. This coupler has a quite small device size, with a height of approximately 12 µm, achieved by introducing an effective spot-size converter configured with the combination of an extremely short Si exponential-inverse taper and a dome-structured SiO2 lens formed on the coupler top. The designed coupler shows high-efficiency optical coupling, with a loss of 0.8 dB for TE polarized light, as well as broad-band coupling with a 0.5-dB-loss band of 420 nm.

  12. The design of double telecentric lens with large aperture based on machine vision

    NASA Astrophysics Data System (ADS)

    Dong, Meng; Xiang, Yang; Tong, Jian; Li, Qi

    2014-12-01

    In recent years machine vision technology obtained the application in many fields, such as the industry, medical systems and national defence. Researches on the machine vision of the on-line and real-time detecting system. By the aid of optical engineering software ZEMAX, a telecentric optical system is designed, which uses a 1 inch CCD image sensor with 5.5μm pixel size. It can measure the target size and non-contact, with the maximum measurement range of 300mm and the resolution of 0.2mm, magnification is -0.053, the distortion is less than 0.1 percent. The MTF of this system is more than 0.5 in 70lp/mm, and all sorts of the aberrations are corrected well, and the image quality is uniform in all the fields. As the limits of magnification and pixel size of the CCD, the technology of CCD pixel subdivision can be used, and the accuracy can be increased to dozens of times, the accuracy of on-line non-contact measurement System can reach the micron-size. The telecentric degree of the double telecentric lens is very small when the object moves along the optical axis.

  13. Comparison of Turbulent Sensible Heat Flux Determined by Large-Aperture Scintillometer and Eddy Covariance over Urban and Suburban Areas

    NASA Astrophysics Data System (ADS)

    Zhang, He; Zhang, Hongsheng

    2015-01-01

    Field observations of the atmospheric boundary layer were made over urban and suburban areas in the Yangtze River Delta, China. Sensible heat fluxes were obtained by eddy-covariance (EC) systems and large-aperture scintillometers (LASs). The results indicated that (1) the sensible heat flux obtained by LAS was less noisy and slightly larger than that obtained by EC over both urban and suburban surfaces; (2) the values of were higher when the correlation coefficient of vertical wind speed and temperature () was smaller. Lower values of were due to low-frequency trends. The urban values of were smaller than suburban values at low values; (3) the sensible heat flux determined by LAS was improved by use of the Monin-Obukhov similarity theory of the temperature structure parameter over urban and suburban areas, and the improvement is more significant over urban surface areas.

  14. Multilayer coated grazing incidence condenser for large numerical aperture objective at wavelength of 4.5 nm.

    PubMed

    Ejima, T; Hatano, T; Ohno, K; Fukayama, T; Aihara, S; Yanagihara, M; Tsuru, T

    2014-10-10

    A grazing incidence condenser is developed for objectives with large numerical aperture working in Carbon-window wavelength region (λ=4.4-5.0  nm) with the use of a point light source. The condenser is composed of four pieces of toroidal mirrors and a piece of the mirror was fabricated to evaluate the performance of the mirror. The radii of the toroidal mirror are determined by ray-trace calculation, and each radius of the mirror substrate and the roughness of the polished surface were evaluated to satisfy the designed parameter. A Co/C reflection multilayer is also designed to reflect soft x-ray light at 4.5 nm wavelength, and the reflection multilayer was deposited on the mirror surface. Measured reflectance of the toroidal mirror with the reflection multilayer is higher than 0.32 at 4.5 nm wavelength.

  15. The Advanced Technology Large Aperture Space Telescope (ATLAST): Science Drivers, Technology Developments, and Synergies with Other Future Facilities

    NASA Technical Reports Server (NTRS)

    Postman, Marc; Brown, Tom; Sembach, Kenneth; Giavalisco, Mauro; Traub, Wesley; Stapelfeldt, Karl; Calzetti, Daniela; Oegerle, William; Rich, R. Michael; Stahl, H. Philip; hide

    2011-01-01

    The Advanced Technology Large-Aperture Space Telescope (ATLAST) is a concept for an 8-meter to 16-meter UVOIR space observatory for launch in the 2025-2030 era. ATLAST will allow astronomers to answer fundamental questions at the forefront of modern astrophysics, including "Is there life elsewhere in the Galaxy?" We present a range of science drivers that define the main performance requirements for ATLAST (8 to 16 milliarcsec angular resolution, diffraction limited imaging at 0.5 m wavelength, minimum collecting area of 45 square meters, high sensitivity to light wavelengths from 0.1 m to 2.4 m, high stability in wavefront sensing and control). We will also discuss the synergy between ATLAST and other anticipated future facilities (e.g., TMT, EELT, ALMA) and the priorities for technology development that will enable the construction for a cost that is comparable to current generation observatory-class space missions.

  16. The study on servo-control system in the large aperture telescope

    NASA Astrophysics Data System (ADS)

    Hu, Wei; Zhenchao, Zhang; Daxing, Wang

    2008-08-01

    Large astronomical telescope or extremely enormous astronomical telescope servo tracking technique will be one of crucial technology that must be solved in researching and manufacturing. To control technique feature of large astronomical telescope or extremely enormous astronomical telescope, this paper design a sort of large astronomical telescope servo tracking control system. This system composes a principal and subordinate distributed control system, host computer sends steering instruction and receive slave computer functional mode, slave computer accomplish control algorithm and execute real-time control. Large astronomical telescope servo control use direct drive machine, and adopt DSP technology to complete direct torque control algorithm, Such design can not only increase control system performance, but also greatly reduced volume and costs of control system, which has a significant occurrence. The system design scheme can be proved reasonably by calculating and simulating. This system can be applied to large astronomical telescope.

  17. Approaches to the Processing of Data from Large Aperture Acoustic Vertical Line Arrays

    DTIC Science & Technology

    1990-04-01

    50 3.4 GSM eigenrays across the very large vertical line array .............. 51 3.5 Conventional beam form er output...54 3.10 GSM eigenrays across the large vertical line array .................. 55 3.11 Conventional beam form er...GSM eigenrays at 162 km and at the sound axis .................... 80 4.8 ATLAS transmission loss versus range at 20 m depth ................ 81 4.9

  18. Quantitative comparison of terahertz emission from (100) InAs surfaces and a GaAs large-aperture photoconductive switch at high fluences.

    PubMed

    Reid, Matthew; Fedosejevs, Robert

    2005-01-01

    InAs has previously been reported to be an efficient emitter of terahertz radiation at low excitation fluences by use of femtosecond laser pulses. The scaling and saturation of terahertz emission from a (100) InAs surface as a function of excitation fluence is measured and quantitatively compared with the emission from a GaAs large-aperture photoconductive switch. We find that, although the instantaneous peak radiated terahertz field from (100) InAs exceeds the peak radiated signals from a GaAs large-aperture photoconductive switch biased at 1.6 kV/cm, the pulse duration is shorter. For the InAs source the total energy radiated is less than can be obtained from a GaAs large-aperture photoconductive switch.

  19. An opposed-anvil-type apparatus with an optical window and a wide-angle aperture for neutron diffraction

    NASA Astrophysics Data System (ADS)

    Iizuka, Riko; Yagi, Takehiko; Gotou, Hirotada; Komatsu, Kazuki; Kagi, Hiroyuki

    2012-09-01

    We designed new anvil assemblies for acquiring high-quality neutron diffraction data and ruby fluorescence spectra inside a sample chamber. The conical aperture of Ni-binded WC anvils was expanded by a factor of two. A hybrid gasket made of TiZr- and Al-alloy was developed to prevent outward extrusion. A small and optically transparent window of moissanite was introduced to allow for the determination of pressure and hydrostaticity by measurement of ruby fluorescence spectra. High pressure-generation tests that make use of Bi electrical conductivity and ruby pressure markers revealed that pressure could be determined over 10 GPa. In situ synchrotron X-ray diffraction experiments were also carried out using NaCl as the pressure calibrants. The maximum pressure achieved was approximately 13 GPa. The neutron diffraction intensity from the newly generated anvil assemblies was 2.5-3.0 times greater than that using the standard toroidal anvil assemblies used previously.

  20. A spatio-temporally compensated acousto-optic scanner for two-photon microscopy providing large field of view.

    PubMed

    Kremer, Y; Léger, J-F; Lapole, R; Honnorat, N; Candela, Y; Dieudonné, S; Bourdieu, L

    2008-07-07

    Acousto-optic deflectors (AOD) are promising ultrafast scanners for non-linear microscopy. Their use has been limited until now by their small scanning range and by the spatial and temporal dispersions of the laser beam going through the deflectors. We show that the use of AOD of large aperture (13mm) compared to standard deflectors allows accessing much larger field of view while minimizing spatio-temporal distortions. An acousto-optic modulator (AOM) placed at distance of the AOD is used to compensate spatial and temporal dispersions. Fine tuning of the AOM-AOD setup using a frequency-resolved optical gating (GRENOUILLE) allows elimination of pulse front tilt whereas spatial chirp is minimized thanks to the large aperture AOD.