Science.gov

Sample records for optical alignment techniques

  1. Optical center alignment technique based on inner profile measurement method

    NASA Astrophysics Data System (ADS)

    Wakayama, Toshitaka; Yoshizawa, Toru

    2014-05-01

    Center alignment is important technique to tune up the spindle of various precision machines in manufacturing industry. Conventionally such a tool as a dial indicator has been used to adjust and to position the axis by manual operations of a technical worker. However, it is not easy to precisely control its axis. In this paper, we developed the optical center alignment technique based on inner profile measurement using a ring beam device. In this case, the center position of the cylinder hole can be determined from circular profile detected by optical sectioning method using a ring beam device. In our trials, the resolution of the center position is proved less than 10 micrometers in extreme cases. This technique is available for practical applications in machine tool industry.

  2. Pupil Alignment Measuring Technique and Alignment Reference for Instruments or Optical Systems

    NASA Technical Reports Server (NTRS)

    Hagopian, John G.

    2010-01-01

    A technique was created to measure the pupil alignment of instruments in situ by measuring calibrated pupil alignment references (PARs) in instruments. The PAR can also be measured using an alignment telescope or an imaging system. PAR allows the verification of the science instrument (SI) pupil alignment at the integrated science instrument module (ISIM) level of assembly at ambient and cryogenic operating temperature. This will allow verification of the ISIM+SI alignment, and provide feedback to realign the SI if necessary.

  3. A Toolbox of Metrology-Based Techniques for Optical System Alignment

    NASA Technical Reports Server (NTRS)

    Coulter, Phillip; Ohl, Raymond G.; Blake, Peter N.; Bos, Brent J.; Eichhorn, William L.; Gum, Jeffrey S.; Hadjimichael, Theodore J.; Hagopian, John G.; Hayden, Joseph E.; Hetherington, Samuel E.; Kubalak, David A.; McLean, Kyle F.; McMann, Joseph; Redman, Kevin W.; Sampler, Henry P.; Wenzel, Greg W.; Young, Jerrod L.

    2016-01-01

    The NASA Goddard Space Flight Center (GSFC) and its partners have broad experience in the alignment of flight optical instruments and spacecraft structures. Over decades, GSFC developed alignment capabilities and techniques for a variety of optical and aerospace applications. In this paper, we provide an overview of a subset of the capabilities and techniques used on several recent projects in a "toolbox" format. We discuss a range of applications, from small-scale optical alignment of sensors to mirror and bench examples that make use of various large-volume metrology techniques. We also discuss instruments and analytical tools.

  4. A Toolbox of Metrology-Based Techniques for Optical System Alignment

    NASA Technical Reports Server (NTRS)

    Coulter, Phillip; Ohl, Raymond G.; Blake, Peter N.; Bos, Brent J.; Casto, Gordon V.; Eichhorn, William L.; Gum, Jeffrey S.; Hadjimichael, Theodore J.; Hagopian, John G.; Hayden, Joseph E.; Hicks, Samantha L.; Kubalak, Dave; Mclean, Kyle F.; McMann, Joseph; Redman, Kevin; Wenzel, Greg; Young, Jerrod

    2016-01-01

    The NASA Goddard Space Flight Center (GSFC) and its partners have broad experience in the alignment of flight optical instruments and spacecraft structures. Over decades, GSFC developed alignment capabilities and techniques for a variety of optical and aerospace applications. In this paper, we provide an overview of a subset of the capabilities and techniques used on several recent projects in a toolbox format. We discuss a range of applications, from small-scale optical alignment of sensors to mirror and bench examples that make use of various large-volume metrology techniques. We also discuss instruments and analytical tools.

  5. Alignment signal extraction of the optically degenerate RSE interferometer using the wave front sensing technique

    NASA Astrophysics Data System (ADS)

    Sato, S.; Kawamura, S.

    2008-07-01

    The alignment sensing and control scheme of the resonant sideband extraction interferometer is still an unsettled issue for the next-generation gravitational wave antennas. The issue is that it is difficult to extract separate error signals for all 12 angular degrees of freedom, which is mainly arising from the complexity of the optical system and cavity 'degeneracy'. We have suggested a new sensing scheme giving reasonably separated signals which is fully compatible with the length sensing scheme. The key of this idea is to resolve the 'degeneracy' of the optical cavities. By choosing an appropriate Gouy phase for the degenerate cavities, alignment error signals with much less admixtures can be extracted.

  6. Optical tools and techniques for aligning solar payloads with the SPARCS control system. [Solar Pointing Aerobee Rocket Control System

    NASA Technical Reports Server (NTRS)

    Thomas, N. L.; Chisel, D. M.

    1976-01-01

    The success of a rocket-borne experiment depends not only on the pointing of the attitude control system, but on the alignment of the attitude control system to the payload. To ensure proper alignment, special optical tools and alignment techniques are required. Those that were used in the SPARCS program are described and discussed herein. These tools include theodolites, autocollimators, a 38-cm diameter solar simulator, a high-performance 1-m heliostat to provide a stable solar source during the integration of the rocket payload, a portable 75-cm sun tracker for use at the launch site, and an innovation called the Solar Alignment Prism. Using the real sun as the primary reference under field conditions, the Solar Alignment Prism facilitates the coalignment of the attitude sun sensor with the payload. The alignment techniques were developed to ensure the precise alignment of the solar payloads to the SPARCS attitude sensors during payload integration and to verify the required alignment under field conditions just prior to launch.

  7. PILOT optical alignment

    NASA Astrophysics Data System (ADS)

    Longval, Y.; Mot, B.; Ade, P.; André, Y.; Aumont, J.; Baustista, L.; Bernard, J.-Ph.; Bray, N.; de Bernardis, P.; Boulade, O.; Bousquet, F.; Bouzit, M.; Buttice, V.; Caillat, A.; Charra, M.; Chaigneau, M.; Crane, B.; Crussaire, J.-P.; Douchin, F.; Doumayrou, E.; Dubois, J.-P.; Engel, C.; Etcheto, P.; Gélot, P.; Griffin, M.; Foenard, G.; Grabarnik, S.; Hargrave, P..; Hughes, A.; Laureijs, R.; Lepennec, Y.; Leriche, B.; Maestre, S.; Maffei, B.; Martignac, J.; Marty, C.; Marty, W.; Masi, S.; Mirc, F.; Misawa, R.; Montel, J.; Montier, L.; Narbonne, J.; Nicot, J.-M.; Pajot, F.; Parot, G.; Pérot, E.; Pimentao, J.; Pisano, G.; Ponthieu, N.; Ristorcelli, I.; Rodriguez, L.; Roudil, G.; Salatino, M.; Savini, G.; Simonella, O.; Saccoccio, M.; Tapie, P.; Tauber, J.; Torre, J.-P.; Tucker, C.

    2016-07-01

    PILOT is a balloon-borne astronomy experiment designed to study the polarization of dust emission in the diffuse interstellar medium in our Galaxy at wavelengths 240 μm with an angular resolution about two arcminutes. Pilot optics is composed an off-axis Gregorian type telescope and a refractive re-imager system. All optical elements, except the primary mirror, are in a cryostat cooled to 3K. We combined the optical, 3D dimensional measurement methods and thermo-elastic modeling to perform the optical alignment. The talk describes the system analysis, the alignment procedure, and finally the performances obtained during the first flight in September 2015.

  8. MUSE optical alignment procedure

    NASA Astrophysics Data System (ADS)

    Laurent, Florence; Renault, Edgard; Loupias, Magali; Kosmalski, Johan; Anwand, Heiko; Bacon, Roland; Boudon, Didier; Caillier, Patrick; Daguisé, Eric; Dubois, Jean-Pierre; Dupuy, Christophe; Kelz, Andreas; Lizon, Jean-Louis; Nicklas, Harald; Parès, Laurent; Remillieux, Alban; Seifert, Walter; Valentin, Hervé; Xu, Wenli

    2012-09-01

    MUSE (Multi Unit Spectroscopic Explorer) is a second generation VLT integral field spectrograph (1x1arcmin² Field of View) developed for the European Southern Observatory (ESO), operating in the visible wavelength range (0.465-0.93 μm). A consortium of seven institutes is currently assembling and testing MUSE in the Integration Hall of the Observatoire de Lyon for the Preliminary Acceptance in Europe, scheduled for 2013. MUSE is composed of several subsystems which are under the responsibility of each institute. The Fore Optics derotates and anamorphoses the image at the focal plane. A Splitting and Relay Optics feed the 24 identical Integral Field Units (IFU), that are mounted within a large monolithic instrument mechanical structure. Each IFU incorporates an image slicer, a fully refractive spectrograph with VPH-grating and a detector system connected to a global vacuum and cryogenic system. During 2011, all MUSE subsystems were integrated, aligned and tested independently in each institute. After validations, the systems were shipped to the P.I. institute at Lyon and were assembled in the Integration Hall This paper describes the end-to-end optical alignment procedure of the MUSE instrument. The design strategy, mixing an optical alignment by manufacturing (plug and play approach) and few adjustments on key components, is presented. We depict the alignment method for identifying the optical axis using several references located in pupil and image planes. All tools required to perform the global alignment between each subsystem are described. The success of this alignment approach is demonstrated by the good results for the MUSE image quality. MUSE commissioning at the VLT (Very Large Telescope) is planned for 2013.

  9. Optically Aligned Drill Press

    NASA Technical Reports Server (NTRS)

    Adderholdt, Bruce M.

    1994-01-01

    Precise drill press equipped with rotary-indexing microscope. Microscope and drill exchange places when turret rotated. Microscope axis first aligned over future hole, then rotated out of way so drill axis assumes its precise position. New procedure takes less time to locate drilling positions and produces more accurate results. Apparatus adapted to such other machine tools as milling and measuring machines.

  10. Prism Window for Optical Alignment

    NASA Technical Reports Server (NTRS)

    Tang, Hong

    2008-01-01

    A prism window has been devised for use, with an autocollimator, in aligning optical components that are (1) required to be oriented parallel to each other and/or at a specified angle of incidence with respect to a common optical path and (2) mounted at different positions along the common optical path. The prism window can also be used to align a single optical component at a specified angle of incidence. Prism windows could be generally useful for orienting optical components in manufacture of optical instruments. "Prism window" denotes an application-specific unit comprising two beam-splitter windows that are bonded together at an angle chosen to obtain the specified angle of incidence.

  11. Optical alignment techniques for line-imaging velocity interferometry and line-imaging self-emission of targets at the National Ignition Facility (NIF)

    SciTech Connect

    Malone, Robert; Celeste, John; Celliers, Peter; Frogget, Brent; Robert Guyton,,; Kaufman, Morris; Lee, Tony; MacGowan, Brian; Ng, Edmend; Reinbachs, Imants; Robinson, Ronald; Tunnell, Thomas; Watts, Phillip

    2007-08-01

    The National Ignition Facility (NIF) requires optical diagnostics for measuring shock velocities in shock physics experiments. The nature of the NIF facility requires the alignment of complex three-dimensional optical systems of very long distances. Access to the alignment mechanisms can be limited, and any alignment system must be operator friendly. The Velocity Interferometer System for Any Reflector (VISAR) measures shock velocities, shock breakout times, and emission of 1- to 5-mm targets at a location remote to the NIF target chamber. Three optical systems using the same vacuum chamber port each have a total track of 21 m. All optical lenses are on kinematic mounts or sliding rails, enabling pointing accuracy of the optical axis to be checked. Counter-propagating laser beams (orange and red) align these diagnostics to a listing of tolerances. Movable aperture cards, placed before and after lens groups, show the spread of alignment spots created by the orange and red alignment lasers. Optical elements include 1-in. to 15-in. diameter mirrors, lenses with up to 10.5-in. diameters, beamsplitters, etalons, dove prisms, filters, and pellicles. Alignment of more than 75 optical elements must be verified before each target shot. Archived images from eight alignment cameras prove proper alignment before each shot.

  12. Optical Alignment Techniques for Line-Imaging Velocity Interferometry and Line-Imaging Self-Emission of Targets at the National Ignition Facility (NIF)

    SciTech Connect

    Malone, R M; Celeste, J R; Celliers, P M; Frogget, B .; Guyton, R L; Kaufman, M I; Lee, T L; MacGowan, B J; Ng, E W; Reinbachs, I P; Robinson, R B; Tunnell, T W; Watts, P W

    2007-07-31

    The National Ignition Facility (NIF) requires optical diagnostics for measuring shock velocities in shock physics experiments. The nature of the NIF facility requires the alignment of complex three-dimensional optical systems of very long distances. Access to the alignment mechanisms can be limited, and any alignment system must be operator friendly. The Velocity Interferometer System for Any Reflector measures shock velocities, shock breakout times, and emission of 1- to 5-mm targets at a location remote to the NIF target chamber. Three optical systems using the same vacuum chamber port each have a total track of 21 meters. All optical lenses are on kinematic mounts or sliding rails, enabling pointing accuracy of the optical axis to be checked. Counter-propagating laser beams (orange and red) align these diagnostics to a listing of tolerances. Movable aperture cards, placed before and after lens groups, show the spread of alignment spots created by the orange and red alignment lasers. Optical elements include 1-in. to 15-in. diameter mirrors, lenses with up to 10.5-in. diameters, beamsplitters, etalons, dove prisms, filters, and pellicles. Alignment of more than 75 optical elements must be verified before each target shot. Archived images from eight alignment cameras prove proper alignment before each shot.

  13. Optical alignment techniques for line-imaging velocity interferometry and line-imaging self-emission of targets at the National Ignition Facility (NIF)

    NASA Astrophysics Data System (ADS)

    Malone, Robert M.; Celeste, John R.; Celliers, Peter M.; Frogget, Brent C.; Guyton, Robert L.; Kaufman, Morris I.; Lee, Tony L.; MacGowan, Brian J.; Ng, Edmund W.; Reinbachs, Imants P.; Robinson, Ronald B.; Tunnell, Thomas W.; Watts, Phillip W.

    2007-09-01

    The National Ignition Facility (NIF) requires optical diagnostics for measuring shock velocities in shock physics experiments. The nature of the NIF facility requires the alignment of complex three-dimensional optical systems of very long distances. Access to the alignment mechanisms can be limited, and any alignment system must be operator-friendly. The Velocity Interferometer System for Any Reflector (VISAR) measures shock velocities and shock breakout times of 1- to 5-mm targets at a location remote to the NIF target chamber. A third imaging system measures self-emission of the targets. These three optical systems using the same vacuum chamber port each have a total track of 21 m. All optical lenses are on kinematic mounts or sliding rails, enabling pointing accuracy of the optical axis to be systematically checked. Counter-propagating laser beams (orange and red) align these diagnostics to a listing of tolerances. Floating apertures, placed before and after lens groups, display misalignment by showing the spread of alignment spots created by the orange and red alignment lasers. Optical elements include 1-in. to 15-in. diameter mirrors, lenses with up to 10.5-in. diameters, beam splitters, etalons, dove prisms, filters, and pellicles. Alignment of more than 75 optical elements must be verified before each target shot. Archived images from eight alignment cameras prove proper alignment is achieved before each shot.

  14. Laser-optic instruments improve machinery alignment

    SciTech Connect

    Bloch, H.P.

    1987-10-12

    Laser-optic alignment systems are fast becoming cost-effective devices that improve the accuracy and speed of machinery shaft alignment. Because of the difficulty, if not impossibility, of aligning operating machinery, cold alignment specifications must be determined to compensate for thermal growth so that the shaft alignment remains within tolerances when the machine reaches normal operating temperature. Some methods for accomplishing this are reviewed here. Three years' field experience with laser-optic alignment systems shows that many of these limitations can be eliminated, resulting in a more accurate alignment in less time. Some actual field alignments are given as examples of the improvement achieved by the use of laser equipment, and a procedure is given that shows how the laser-optic system may be used to determine running alignment changes caused by thermal growth.

  15. Reducing beam shaper alignment complexity: diagnostic techniques for alignment and tuning

    NASA Astrophysics Data System (ADS)

    Lizotte, Todd E.

    2011-10-01

    Safe and efficient optical alignment is a critical requirement for industrial laser systems used in a high volume manufacturing environment. Of specific interest is the development of techniques to align beam shaping optics within a beam line; having the ability to instantly verify by a qualitative means that each element is in its proper position as the beam shaper module is being aligned. There is a need to reduce these types of alignment techniques down to a level where even a newbie to optical alignment will be able to complete the task. Couple this alignment need with the fact that most laser system manufacturers ship their products worldwide and the introduction of a new set of variables including cultural and language barriers, makes this a top priority for manufacturers. Tools and methodologies for alignment of complex optical systems need to be able to cross these barriers to ensure the highest degree of up time and reduce the cost of maintenance on the production floor. Customers worldwide, who purchase production laser equipment, understand that the majority of costs to a manufacturing facility is spent on system maintenance and is typically the largest single controllable expenditure in a production plant. This desire to reduce costs is driving the trend these days towards predictive and proactive, not reactive maintenance of laser based optical beam delivery systems [10]. With proper diagnostic tools, laser system developers can develop proactive approaches to reduce system down time, safe guard operational performance and reduce premature or catastrophic optics failures. Obviously analytical data will provide quantifiable performance standards which are more precise than qualitative standards, but each have a role in determining overall optical system performance [10]. This paper will discuss the use of film and fluorescent mirror devices as diagnostic tools for beam shaper module alignment off line or in-situ. The paper will also provide an overview

  16. Optical alignment techniques for line-imaging velocity interferometry and line-imaging self-emulsion of targets at the National Ignition Facility (NIF)

    SciTech Connect

    Robert M. Malone, Brent C. Frogget, Morris I. Kaufman, Thomas W. Tunnell, Robert L. Guyton, Imants P. Reinbachs, Phillip W. Watts, et al.

    2007-08-31

    The National Ignition Facility (NIF) requires optical diagnostics for measuring shock velocities in shock physics experiments. The Velocity Interferometer System for Any Reflector (VISAR) measures shock velocities, shock breakout times, and emission of 1- to 5-mm targets at a location remote to the NIF target chamber. Three optical systems using the same vacuum chamber port each have a total track of 69 feet. All optical lenses are on kinematic mounts or sliding rails, enabling pointing accuracy of the optical axis to be checked. Counter-propagating laser beams (orange and red) align these diagnostics to a listing of tolerances. The orange alignment laser is introduced at the entrance to the two-level interferometer table and passes forward through the optical systems to the recording streak cameras. The red alignment laser is introduced in front of the recording streak cameras and passes in the reverse direction through all optical elements, out of the interferometer table, eventually reaching the target chamber center. Red laser wavelength is selected to be at the 50 percent reflection point of a special beamsplitter used to separate emission light from the Doppler-shifted interferometer light. Movable aperture cards, placed before and after lens groups, show the spread of alignments spots created by the orange and red alignment lasers. Optical elements include 1- to 15-inch-diameter mirrors, lenses with up to 10.5-inch diameters, beamsplitters, etalons, dove prisms, filters, and pellicles. Alignment of more than 75 optical elements must be verified before each target shot. Archived images from eight alignment cameras prove proper alignment before each shot.

  17. Use laser-optics for machinery alignment

    SciTech Connect

    Bloch, H.P.

    1987-10-01

    Many sources attribute most bearing overload and destructive vibration in industrial machinery to shaft misalignment. There is considerable disagreement as to the alignment quality required. There is also little agreement on suitable calculation methods and achievable accuracy for anticipated thermal growth of machinery (necessary if running alignment is to remain acceptable). This article examines existing alignment quality guidelines for relevance and consistency, and reviews the application of laser-optic alignment systems based on three years of field experience.

  18. Optical alignment III; Proceedings of the Meeting, Los Angeles, CA, Jan. 21, 22, 1986

    NASA Astrophysics Data System (ADS)

    Ruda, Mitchell C.

    Recent progress in the field of optical alignment is summarized in terms of alignment systems, active alignment mechanisms and techniques. Attention is given to the alignment of multiple beam and multiple mirror systems and to active alignment of systems with pointing requirements which exceed the mechanical and environmmental stability of the associated optical mounting systems. The design of optical alignment adjustment mechanisms is explored, with emphasis on calibrating as many subsystems as possible during assembly. Alignment techniques are also described for linear arrays and transmitter/receiver optical axes. The works reported are of significance for astronomy and aerospace applications.

  19. Optical alignment of a pupil imaging spectrometer

    NASA Technical Reports Server (NTRS)

    Horchem, Stephen D.; Kohrman, Richard J.

    1989-01-01

    The GOES Sounder is a 19-channel discrete filter spectrometer with an additional channel for star sensing. This paper presents the GOES Sounder's instrument optics and compensations, alignment rationale, and alignment mechanism and sensitivities. The results of a line of sight tolerance analysis of the instrument are described, and the prealignment and instrument coregistration are addressed.

  20. High-performance semiconductor optical amplifier array for self-aligned packaging using Si V-groove flip-chip technique

    NASA Astrophysics Data System (ADS)

    Leclerc, D.; Brosson, P.; Pommereau, F.; Ngo, R.; Doussiere, P.; Mallecot, F.; Gavignet, P.; Wamsler, I.; Laube, G.; Hunziker, W.

    1995-05-01

    A high performance four-tilted stripe semiconductor optical amplifier array, with low polarization sensitivity and very low-gain ripple, compatible with self-aligned flip-chip mounting on a Si motherboard is reported. Up to 32 dB of internal gain with 2-dB polarization sensitivity is obtained. A multifiber module has been realized, following an almost static optical alignment procedure, showing no degradation of the SOA array performances. Fiber-to-fiber gain, measured on the four stripes, is 14.4 +/- 1.3 dB with a gain ripple below +/- 0.1 dB.

  1. Fiber optics welder having movable aligning mirror

    DOEpatents

    Higgins, Robert W.; Robichaud, Roger E.

    1981-01-01

    A system for welding fiber optic waveguides together. The ends of the two fibers to be joined together are accurately, collinearly aligned in a vertical orientation and subjected to a controlled, diffuse arc to effect welding and thermal conditioning. A front-surfaced mirror mounted at a 45.degree. angle to the optical axis of a stereomicroscope mounted for viewing the junction of the ends provides two orthogonal views of the interface during the alignment operation.

  2. Free-space optical communication alignment system

    NASA Astrophysics Data System (ADS)

    Mariola, M.; Petruccione, F.

    2016-10-01

    Optical communication systems in free space require a coarse and fine alignment system to align the receiver and transmitter. In general a coarse alignment is not entirely accurate to transmit the laser beacon in the exact direction of the visible field of the camera. During this process, some algorithms such as the raster, spiral and raster spiral scan algorithm can be used to find the spot of the laser beacon. Applications that require to transmit data in form of polarization signals, such as quantum cryptography, requires a polarisation bases alignment system to transmit and receive the photons. In this paper we present a fine alignment system using a polarised laser beacon. The system proposed was subdivided into a coarse and fine alignment system. The coarse alignment was implemented by using the GPS to acquire the geographical position of the transmitter, receiver and a reference point. The fine alignment was achieved by using a polarised laser beacon from the receiver to the transmitter and a camera located on the transmitter side. The algorithm presented was capable of excluding the background noise. Furthermore the polarisation of the laser beacon was used to align the polarisation bases of the transmitter and the receiver.

  3. Scalable cell alignment on optical media substrates.

    PubMed

    Anene-Nzelu, Chukwuemeka G; Choudhury, Deepak; Li, Huipeng; Fraiszudeen, Azmall; Peh, Kah-Yim; Toh, Yi-Chin; Ng, Sum Huan; Leo, Hwa Liang; Yu, Hanry

    2013-07-01

    Cell alignment by underlying topographical cues has been shown to affect important biological processes such as differentiation and functional maturation in vitro. However, the routine use of cell culture substrates with micro- or nano-topographies, such as grooves, is currently hampered by the high cost and specialized facilities required to produce these substrates. Here we present cost-effective commercially available optical media as substrates for aligning cells in culture. These optical media, including CD-R, DVD-R and optical grating, allow different cell types to attach and grow well on them. The physical dimension of the grooves in these optical media allowed cells to be aligned in confluent cell culture with maximal cell-cell interaction and these cell alignment affect the morphology and differentiation of cardiac (H9C2), skeletal muscle (C2C12) and neuronal (PC12) cell lines. The optical media is amenable to various chemical modifications with fibronectin, laminin and gelatin for culturing different cell types. These low-cost commercially available optical media can serve as scalable substrates for research or drug safety screening applications in industry scales.

  4. Optical Alignment of the Spherical Antenna Measurement System

    DTIC Science & Technology

    1997-11-01

    theodolite with built-in autocollimation capability, and a unique target mirror assembly with the target viewable from both sides. A hand-held programmable ... calculator is also used to calculate angular positions and distances. Numerous techniques and procedures developed for optical alignment are described

  5. Optical alignment of oval graphene flakes.

    PubMed

    Mobini, E; Rahimzadegan, A; Alaee, R; Rockstuhl, C

    2017-03-15

    Patterned graphene, as an atomically thin layer, supports localized surface plasmon polaritons at mid-infrared or far-infrared frequencies. This provides a pronounced optical force/torque in addition to large optical cross sections and will make it an ideal candidate for optical manipulation. Here, we study the optical force and torque exerted by a linearly polarized plane wave on circular and oval graphene flakes (single layers of graphene). While the torque vanishes for circular flakes, the finite torque allows rotating and orienting oval flakes relative to the electric field polarization. Depending on the wavelength, the alignment is either parallel or perpendicular to the electric field vector. In our contribution, we rely on a full-wave numerical simulation and also on an analytical model that treats the graphene flakes in a dipole approximation. The presented results reveal a good level of control on the spatial alignment of graphene flakes subjected to far-infrared illumination.

  6. Optical Alignment of the Global Precipitation Measurement (GPM) Star Trackers

    NASA Technical Reports Server (NTRS)

    Hetherington, Samuel; Osgood, Dean; McMann, Joe; Roberts, Viki; Gill, James; Mclean, Kyle

    2013-01-01

    The optical alignment of the star trackers on the Global Precipitation Measurement (GPM) core spacecraft at NASA Goddard Space Flight Center (GSFC) was challenging due to the layout and structural design of the GPM Lower Bus Structure (LBS) in which the star trackers are mounted as well as the presence of the star tracker shades that blocked line-of-sight to the primary star tracker optical references. The initial solution was to negotiate minor changes in the original LBS design to allow for the installation of a removable item of ground support equipment (GSE) that could be installed whenever measurements of the star tracker optical references were needed. However, this GSE could only be used to measure secondary optical reference cube faces not used by the star tracker vendor to obtain the relationship information and matrix transformations necessary to determine star tracker alignment. Unfortunately, due to unexpectedly large orthogonality errors between the measured secondary adjacent cube faces and the lack of cube calibration data, we required a method that could be used to measure the same reference cube faces as originally measured by the vendor. We describe an alternative technique to theodolite auto-collimation for measurement of an optical reference mirror pointing direction when normal incidence measurements are not possible. This technique was used to successfully align the GPM star trackers and has been used on a number of other NASA flight projects. We also discuss alignment theory as well as a GSFC-developed theodolite data analysis package used to analyze angular metrology data.

  7. Optical-precision alignment of diffraction grating mold in moire interferometry

    NASA Technical Reports Server (NTRS)

    Joh, D.

    1992-01-01

    A high-precision optical method is presented for aligning diffraction grating molds with the edges of specimens in moire interferometry. The alignment fixture is simple and convenient to operate. The conventional method of grating-mold alignment has a wide band of uncertainty in the range of error which is not compatible with the required precision of high-sensitivity moire interferometry. Following a description of the alignment technique, both the single-edge and parallel-edge guide bar optical alignment methods are introduced and compared.

  8. Alignment method of off-axis RC reflective optical system

    NASA Astrophysics Data System (ADS)

    Xue-min, Zhang; Xing, Song; Zhi-jun, Zhang; Hou, Xiao-hua

    2016-10-01

    Off-axis optical system has a wide application in space optics and remote detective area. The high surface shape accuracy can be ensured with the development of advanced manufacture technique. So the only condition which limits the wide application of off-axis optical system is how to realize the precise alignment of it. Based on a RC reflective optical system whose diameter is 400mm, the alignment method which combines the high resolution initial placement and computer-aided alignment is introduced. By designing a system which can measure the off-axis fabrication and off-axis angle precisely, the high resolution initial placement of off-axis mirror can be ensured with a measurement accuracy of +/-0.05mm and +/-10". The good initial placement can give a good initial state, so the computer-aided model can be converged well. The experiment shows that a system which has a good initial placement could have a good wave aberration of 0.04λ after three times iteration adjustment.

  9. Optical alignment of Centaur's inertial guidance system

    NASA Technical Reports Server (NTRS)

    Gordan, Andrew L.

    1987-01-01

    During Centaur launch operations the launch azimuth of the inertial platform's U-accelerometer input axis must be accurately established and maintained. This is accomplished by using an optically closed loop system with a long-range autotheodolite whose line of sight was established by a first-order survey. A collimated light beam from the autotheodolite intercepts a reflecting Porro prism mounted on the platform azimuth gimbal. Thus, any deviation of the Porro prism from its predetermined heading is optically detected by the autotheodolite. The error signal produced is used to torque the azimuth gimbal back to its required launch azimuth. The heading of the U-accelerometer input axis is therefore maintained automatically. Previously, the autotheodolite system could not distinguish between vehicle sway and rotational motion of the inertial platform unless at least three prisms were used. One prism was mounted on the inertial platform to maintain azimuth alignment, and two prisms were mounted externally on the vehicle to track sway. For example, the automatic azimuth-laying theodolite (AALT-SV-M2) on the Saturn vehilce used three prisms. The results of testing and modifying the AALT-SV-M2 autotheodolite to simultaneously monitor and maintain alignment of the inertial platform and track the sway of the vehicle from a single Porro prism.

  10. Sensitive Technique For Detecting Alignment Of Seed Laser

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.

    1994-01-01

    Frequency response near resonance measured. Improved technique for detection and quantification of alignment of injection-seeding laser with associated power-oscillator laser proposed. Particularly useful in indicating alignment at spectral purity greater than 98 percent because it becomes more sensitive as perfect alignment approached. In addition, implemented relatively easily, without turning on power-oscillator laser.

  11. Low cost, high performance, self-aligning miniature optical systems

    PubMed Central

    Kester, Robert T.; Christenson, Todd; Kortum, Rebecca Richards; Tkaczyk, Tomasz S.

    2009-01-01

    The most expensive aspects in producing high quality miniature optical systems are the component costs and long assembly process. A new approach for fabricating these systems that reduces both aspects through the implementation of self-aligning LIGA (German acronym for lithographie, galvanoformung, abformung, or x-ray lithography, electroplating, and molding) optomechanics with high volume plastic injection molded and off-the-shelf glass optics is presented. This zero alignment strategy has been incorporated into a miniature high numerical aperture (NA = 1.0W) microscope objective for a fiber confocal reflectance microscope. Tight alignment tolerances of less than 10 μm are maintained for all components that reside inside of a small 9 gauge diameter hypodermic tubing. A prototype system has been tested using the slanted edge modulation transfer function technique and demonstrated to have a Strehl ratio of 0.71. This universal technology is now being developed for smaller, needle-sized imaging systems and other portable point-of-care diagnostic instruments. PMID:19543344

  12. Emerging optical nanoscopy techniques

    PubMed Central

    Montgomery, Paul C; Leong-Hoi, Audrey

    2015-01-01

    To face the challenges of modern health care, new imaging techniques with subcellular resolution or detection over wide fields are required. Far field optical nanoscopy presents many new solutions, providing high resolution or detection at high speed. We present a new classification scheme to help appreciate the growing number of optical nanoscopy techniques. We underline an important distinction between superresolution techniques that provide improved resolving power and nanodetection techniques for characterizing unresolved nanostructures. Some of the emerging techniques within these two categories are highlighted with applications in biophysics and medicine. Recent techniques employing wider angle imaging by digital holography and scattering lens microscopy allow superresolution to be achieved for subcellular and even in vivo, imaging without labeling. Nanodetection techniques are divided into four subcategories using contrast, phase, deconvolution, and nanomarkers. Contrast enhancement is illustrated by means of a polarized light-based technique and with strobed phase-contrast microscopy to reveal nanostructures. Very high sensitivity phase measurement using interference microscopy is shown to provide nanometric surface roughness measurement or to reveal internal nanometric structures. Finally, the use of nanomarkers is illustrated with stochastic fluorescence microscopy for mapping intracellular structures. We also present some of the future perspectives of optical nanoscopy. PMID:26491270

  13. Laser Alignment Techniques For Simultaneous Machine Tool Geometric Error Detection

    NASA Astrophysics Data System (ADS)

    Ni, J.; Wu, S. M.

    1989-01-01

    An optical measurement system has been developed for the simultaneous detection of multiple geometric error components of machine tools. The system is designed based upon laser alignment techniques where laser beams are used as measurement reference datum. The system can measure simultaneously 5 error components for each moving axis of a machine tool or coordinate measuring machine. They are: two straightness error components, pitch, yaw, and roll errors. Through actual calibration and measurement, the accuracy of the current system is estimated to be 2 µm for straightness measurements and better than 0.05 arcsec for angular error measurements with a 0.5 m offset between a reflecting mirror and a receiving photo sensor.

  14. A Technique for determining the director pretilt angle in cells with hybrid or homeotropic alignment of a nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Vakulin, D. A.

    2015-12-01

    A new technique for determining the director pretilt angle in cells with hybrid or homeotropic alignment of a nematic liquid crystal has been developed. To use this technique, it is necessary to experimentally determine the transmission of an optical system in parallel polarizers and maximum transmission of a cell in crossed polarizers. The technique makes it possible to locally control the liquid crystal director alignment on an aligning surface.

  15. Construction of rugged, ultrastable optical assemblies with optical component alignment at the few microradian level.

    PubMed

    Killow, Christian J; Fitzsimons, Ewan D; Hough, James; Perreur-Lloyd, Michael; Robertson, David I; Rowan, Sheila; Ward, Henry

    2013-01-10

    A method for constructing quasimonolithic, precision-aligned optical assemblies is presented. Hydroxide-catalysis bonding is used, adapted to allow optimization of component fine alignment prior to the bond setting. We demonstrate the technique by bonding a fused silica mirror substrate to a fused silica baseplate. In-plane component placement at the submicrometer level is achieved, resulting in angular control of a reflected laser beam at the sub-10-μrad level. Within the context of the LISA Pathfinder mission, the technique has been demonstrated as suitable for use in space-flight applications. It is expected that there will also be applications in a wide range of areas where accuracy, stability, and strength of optical assemblies are important.

  16. Optical Techniques in Optogenetics

    PubMed Central

    Mohanty, Samarendra K.; Lakshminarayananan, Vasudevan

    2015-01-01

    Optogenetics is an innovative technique for optical control of cells. This field has exploded over the past decade or so and has given rise to great advances in neuroscience. A variety of applications both from the basic and applied research have emerged, turning the early ideas into a powerful paradigm for cell biology, neuroscience and medical research. This review aims at highlighting the basic concepts that are essential for a comprehensive understanding of optogenetics and some important biological/biomedical applications. Further, emphasis is placed on advancement in optogenetics-associated light-based methods for controlling gene expression, spatially-controlled optogenetic stimulation and detection of cellular activities. PMID:26412943

  17. Backup Alignment Devices on Shuttle: Heads-Up Display or Crew Optical Alignment Sight

    NASA Technical Reports Server (NTRS)

    Chavez, Melissa A.

    2011-01-01

    NASA s Space Shuttle was built to withstand multiple failures while still keeping the crew and vehicle safe. Although the design of the Space Shuttle had a great deal of redundancy built into each system, there were often additional ways to keep systems in the best configuration if a failure were to occur. One such method was to use select pieces of hardware in a way for which they were not primarily intended. The primary function of the Heads-Up Display (HUD) was to provide the crew with a display of flight critical information during the entry phase. The primary function of the Crew Optical Alignment Sight (COAS) was to provide the crew an optical alignment capability for rendezvous and docking phases. An alignment device was required to keep the Inertial Measurement Units (IMUs) well aligned for a safe Entry; nominally this alignment device would be the two on-board Star Trackers. However, in the event of a Star Tracker failure, the HUD or COAS could also be used as a backup alignment device, but only if the device had been calibrated beforehand. Once the HUD or COAS was calibrated and verified then it was considered an adequate backup to the Star Trackers for entry IMU alignment. There were procedures in place and the astronauts were trained on how to accurately calibrate the HUD or COAS and how to use them as an alignment device. The calibration procedure for the HUD and COAS had been performed on many Shuttle missions. Many of the first calibrations performed were for data gathering purposes to determine which device was more accurate as a backup alignment device, HUD or COAS. Once this was determined, the following missions would frequently calibrate the HUD in order to be one step closer to having the device ready in case it was needed as a backup alignment device.

  18. Focal Plane Alignment Utilizing Optical CMM

    NASA Technical Reports Server (NTRS)

    Liebe, Carl Christian; Meras, Patrick L.; Clark, Gerald J.; Sedaka, Jack J.; Kaluzny, Joel V.; Hirsch, Brian; Decker, Todd A.; Scholtz, Christopher R.

    2012-01-01

    In many applications, an optical detector has to be located relative to mechanical reference points. One solution is to specify stringent requirements on (1) mounting the optical detector relative to the chip carrier, (2) soldering the chip carrier onto the printed circuit board (PCB), and (3) installing the PCB to the mechanical structure of the subsystem. Figure 1 shows a sketch of an optical detector mounted relative to mechanical reference with high positional accuracy. The optical detector is typically a fragile wafer that cannot be physically touched by any measurement tool. An optical coordinate measuring machine (CMM) can be used to position optical detectors relative to mechanical reference points. This approach will eliminate all requirements on positional tolerances. The only requirement is that the PCB is manufactured with oversized holes. An exaggerated sketch of this situation is shown in Figure 2. The sketch shows very loose tolerances on mounting the optical detector in the chip carrier, loose tolerance on soldering the chip carrier to the PCB, and finally large tolerance on where the mounting screws are located. The PCB is held with large screws and oversized holes. The PCB is mounted loosely so it can move freely around. The optical CMM measures the mechanical reference points. Based on these measurements, the required positions of the optical detector corners can be calculated. The optical CMM is commanded to go to the position where one detector corner is supposed to be. This is indicated with the cross-hairs in Figure 2(a). This figure is representative of the image of the optical CMM monitor. Using a suitable tapping tool, the PCB is manually tapped around until the corner of the optical detector is at the crosshairs of the optical CMM. The CMM is commanded to another corner, and the process is repeated a number of times until all corners of the optical detector are within a distance of 10 to 30 microns of the required position. The situation

  19. Alignment control optical-electronic system with duplex retroreflectors

    NASA Astrophysics Data System (ADS)

    Kleshchenok, Maksim A.; Anisimov, Andrey G.; Lashmanov, Oleg U.; Timofeev, Alexandr N.; Korotaev, Valery V.

    2014-05-01

    In this paper, we consider the influence of various factors and interference invariant transformations measuring information on autoreflection schemes alignment control. Theoretical and experimental studies of an error for biprizm scheme. Shown that the main influencing factors are non-linear transformations in optical systems and the impact of the air path. Experimental studies were conducted based on two alignment control opto- electronic systems in which the control element (CE) is configured as one or two corner-cube retroreflectors.

  20. Use laser optics for on-stream alignment verification

    SciTech Connect

    Block, H.P.

    1991-01-01

    One of the many significant factors influencing machinery reliability in process plants is alignment accuracy. When driven process machines operate in misaligned condition with respect to their drivers, equipment bearings are exposed to additional loads. Vibration severity may increase, bearings will be more highly loaded and equipment life expectancy will diminish. This paper reports on the use of laser optics for on-stream alignment verification.

  1. The Stonehenge technique. A method for aligning coherent bremsstrahlung radiators

    NASA Astrophysics Data System (ADS)

    Livingston, Ken

    2009-05-01

    This paper describes a technique for the alignment of crystal radiators used to produce high energy, linearly polarized photons via coherent bremsstrahlung scattering at electron beam facilities. In these experiments the crystal is mounted on a goniometer which is used to adjust its orientation relative to the electron beam. The angles and equations which relate the crystal lattice, goniometer and electron beam direction are presented here, and the method of alignment is illustrated with data taken at MAMI (the Mainz microtron). A practical guide to setting up a coherent bremsstrahlung facility and installing new crystals using this technique is also included.

  2. Daniel K. Inouye Solar Telescope optical alignment plan

    NASA Astrophysics Data System (ADS)

    Sekulic, Predrag; Liang, Chen; Gonzales, Kerry; Hubbard, Robert P.; Craig, Simon C.

    2016-07-01

    The Daniel K. Inouye Solar Telescope (DKIST) is a 4-meter solar telescope under construction at Haleakala, Hawaii. The challenge of the DKIST optical alignment is the off-axis Gregorian configuration based on an Altitude-Azimuth mount, the independently-rotating Coudé platform and the large number of relay mirrors. This paper describes the optical alignment plan of the complete telescope, including the primary 4.24-m diameter off-axis secondary mirror, the secondary 620 mm diameter off-axis mirror, the transfer optics and the Coudé optics feeding the wavefront correction system and the science instruments. A number of accurate metrology instruments will be used to align the telescope and to reach the performances, including a laser tracker for initial positioning, a theodolite for accurate tilt alignment, a Coordinate Measurement Machine (CMM) arm for local alignment in the Coudé laboratory, and a Shack-Hartmann wavefront sensor to characterize the aberrations by measuring selected target stars. The wavefront will be characterized at the primary focus, the Gregorian focus, the intermediate focus and at the telescope focal plane. The laser tracker will serve also to measure the mirrors positions as function of Altitude angle due to the Telescope Mount Assembly (TMA) structure deflection. This paper describes also the method that will be used to compute the compensating mirrors shift and tilt needed to correct the residual aberrations and position of the focal plane.

  3. Automatic alignment of double optical paths in excimer laser amplifier

    NASA Astrophysics Data System (ADS)

    Wang, Dahui; Zhao, Xueqing; Hua, Hengqi; Zhang, Yongsheng; Hu, Yun; Yi, Aiping; Zhao, Jun

    2013-05-01

    A kind of beam automatic alignment method used for double paths amplification in the electron pumped excimer laser system is demonstrated. In this way, the beams from the amplifiers can be transferred along the designated direction and accordingly irradiate on the target with high stabilization and accuracy. However, owing to nonexistence of natural alignment references in excimer laser amplifiers, two cross-hairs structure is used to align the beams. Here, one crosshair put into the input beam is regarded as the near-field reference while the other put into output beam is regarded as the far-field reference. The two cross-hairs are transmitted onto Charge Coupled Devices (CCD) by image-relaying structures separately. The errors between intersection points of two cross-talk images and centroid coordinates of actual beam are recorded automatically and sent to closed loop feedback control mechanism. Negative feedback keeps running until preset accuracy is reached. On the basis of above-mentioned design, the alignment optical path is built and the software is compiled, whereafter the experiment of double paths automatic alignment in electron pumped excimer laser amplifier is carried through. Meanwhile, the related influencing factors and the alignment precision are analyzed. Experimental results indicate that the alignment system can achieve the aiming direction of automatic aligning beams in short time. The analysis shows that the accuracy of alignment system is 0.63μrad and the beam maximum restoration error is 13.75μm. Furthermore, the bigger distance between the two cross-hairs, the higher precision of the system is. Therefore, the automatic alignment system has been used in angular multiplexing excimer Main Oscillation Power Amplification (MOPA) system and can satisfy the requirement of beam alignment precision on the whole.

  4. Development of alignment-guidance device for grooved roll mill using parallel projection imaging technique

    NASA Astrophysics Data System (ADS)

    Kodama, Toshifumi; Iwata, Teruhisa; Yamagami, Daisaku; Takagi, Keiji

    2013-04-01

    The accuracy in the arrangement of grooved rolls for the finishing rolling mill is of large importance for the good roundness of the bar steel product supplied to the precision machinery components such as the bearing of the high speed motor. Combining telecentric optics, silhouette image processing techniques, and statistical data processing allowed the development of the quantitative alignment guidance technique of the grooved rolls. The developed system demonstrated a high measuring accuracy and was seen to have practical use.

  5. Techniques For Optical Measurement Of Registration

    NASA Astrophysics Data System (ADS)

    Zych, L. J.; Spadini, G.

    1985-07-01

    This paper discusses an optical technique capable of reliably measuring registration to few hundredths of a micron on virtually any layer. It has overcome the accuracy limitations and the proximity effect error present in other optical techniques. In spite of the recent popularity of highly accurate computerized electrical registration measurements optical registration measurements are still popular and necessary. This is because nonconductive layers, including resist, cannot be measured electrically. A quick optical technique with a high degree of accuracy has been developed and put to use. The measurement is made through a microscope, and a computer pattern recognition follows. It is free of the resolution limits inherent in such structures as optical verniers, which are bound to typically 0.1 microns by the grid size used to make the mask. This method employs a direct optical misalignment measurement between two matching structures and is capable of resolving 0.01 microns. It is also free of the proximity effects which make many verniers and pattern recognition schemes inaccurate. Proper microscope calibration, adjustments, and pattern recognition algorithms are key in making this technique work. The apertures must be accurately aligned and the focus properly adjusted to provide the right image. An HP 9000-226 computer has been custom interfaced to a Leitz microscope and a set of algorithms written. The result is a highly accurate, fast, and user friendly optical measurement system capable of measuring registration on all layers.

  6. Proposed technique for vertical alignment of a crane's cable

    NASA Technical Reports Server (NTRS)

    Gera, J., Jr.

    1969-01-01

    Proposed vertical alignment technique senses the attitude of a cranes cable and displays any deviation from the vertical. The system consists of a detector assembly fixed to the boom and a display scope located in the cabin. It has potential application with either fixed-boom cranes or gantries.

  7. Optical alignment and diagnostics for the ATF microundulator FEL oscillator

    SciTech Connect

    Babzien, M.; Ben-Zvi, I.; Fang, J.M.

    1995-12-31

    The microundulator FEL oscillator has a wiggler period of 8.8 mm, and is designed for initial lasing at 0.5 microns with a 50 MeV electron beam. The design and performance of the optical diagnostics and alignment are discussed. A HeNe coalignment laser is mode-matched to the resonator cavity for transverse alignment. Interference fringes are observed in the cavity with a pellicle, allowing an alignment tolerance of +/- 10 micro-radians. The same pellicle is used to produce transition radiation by the electron beam. This enables precise transverse alignment of the electron beam to the resonator axis. The HeNe laser is also used to align the wiggler by backlighting its bore. This method aligns the wiggler to the optic axis to a tolerance of +/- 50 microns. A frequency-doubled,pulsed Nd:YAG laser that produces the electron bunch train is also mode-matched to the FEL cavity. The cavity length is adjusted to resonate with this pulse train. Light from the FEL is transported to the diagnostic room using two separate paths: one for the single pass spontaneous emission, and the second for the multipass cavity output. Several diagnostics (CCD camera, photodiode, photomultiplier tube, joulemeter, spectrometer, and streak camera) are used to characterize the light. These instruments measure light energy per micropulse ranging from 10 femto-Joules to 10 micro-Joules.

  8. Multispectral optical telescope alignment testing for a cryogenic space environment

    NASA Astrophysics Data System (ADS)

    Newswander, Trent; Hooser, Preston; Champagne, James

    2016-09-01

    Multispectral space telescopes with visible to long wave infrared spectral bands provide difficult alignment challenges. The visible channels require precision in alignment and stability to provide good image quality in short wavelengths. This is most often accomplished by choosing materials with near zero thermal expansion glass or ceramic mirrors metered with carbon fiber reinforced polymer (CFRP) that are designed to have a matching thermal expansion. The IR channels are less sensitive to alignment but they often require cryogenic cooling for improved sensitivity with the reduced radiometric background. Finding efficient solutions to this difficult problem of maintaining good visible image quality at cryogenic temperatures has been explored with the building and testing of a telescope simulator. The telescope simulator is an onaxis ZERODUR® mirror, CFRP metered set of optics. Testing has been completed to accurately measure telescope optical element alignment and mirror figure changes in a cryogenic space simulated environment. Measured alignment error and mirror figure error test results are reported with a discussion of their impact on system optical performance.

  9. Preferential alignment of birefringent tissue measured with polarization sensitive techniques

    NASA Astrophysics Data System (ADS)

    Ramella-Roman, J. C.; Ruiz, T.; Ghassemi, P.; Travis, T. E.; Shupp, J. W.; Chue-Sang, J.; Bai, Y.

    2015-02-01

    Assessing collagen alignment is of interest when evaluating a therapeutic strategy and evaluating its outcome in scar management. In this work we introduce a theoretical and experimental methodology for the quantification of collagen and birefringent media alignment based on polarized light transport. The technique relies on the fact that these materials exhibit directional anisotropy. A polarized Monte Carlo model and a spectro-polarimetric imaging system were devised to predict and measure the impact of birefringence on an impinging polarized light beam. Experiments conducted on birefringent phantoms, and biological samples consisting of highly packed parallel birefringent fibers, showed a good agreement with the analytical results.

  10. Application of MATLAB in optical alignment

    NASA Astrophysics Data System (ADS)

    Xiao, Shu; Tang, Yong

    2008-03-01

    The article has mainly introduced a new method in the process of adjusting the average windward area measuring system of cannonball fragment with the aid of MATLAB. The method can not only analyze the amount of deviation qualitatively but also quantitatively, comparing with the traditional method which just can be used for qualitative analyzing. When the measuring system works, four optical axes of CCD cameras should aim at the center point of the universal platform strictly with different object distances and image distances. In the process of assembling and debugging the system, analyzing the image acquired with MATLAB to get the amount of deviation which can be used as gist.

  11. Optical interconnection techniques for Hypercube

    NASA Technical Reports Server (NTRS)

    Johnston, A. R.; Bergman, L. A.; Wu, W. H.

    1988-01-01

    Direct free-space optical interconnection techniques are described for the Hypercube concurrent processor machine using a holographic optical element. Computational requirements and optical constraints on implementation are briefly summarized with regard to topology, power consumption, and available technologies. A hybrid lens/HOE approach is described that can support an eight-dimensional cube of 256 nodes.

  12. Hydrodynamic optical alignment for microflow cytometry.

    PubMed

    Kennedy, Matthew J; Stelick, Scott J; Sayam, Lavanya G; Yen, Andrew; Erickson, David; Batt, Carl A

    2011-03-21

    A microfabricated flow cytometer has been developed that is capable of detecting nearly all of the microparticles in an aqueous suspension. Current design allows for integrated coupling between an optical fiber-based detection system and the particle stream via hydrodynamic focusing. By adjusting the relative flow-rates at the auxiliary inputs of the focusing manifold, the particle stream can be steered out-of-plane relative to the illuminating laser, and similarly the particle stream can be squeezed or expanded. The microfabricated device was constructed in polydimethylsiloxane with cross-sectional microfluidic dimensions of 125 µm×125 µm. Using the present device and method, fluorescent microparticles in aqueous solution were counted at an absolute counting efficiency of 91±4%. The coefficient of variation of the fluorescence pulse-heights for far-red fluorescent microparticles was 15%. The device exhibited a linear response to fluorescence intensity calibration microparticles as shown by comparison with a commercial cytometer instrument.

  13. Precision alignment and calibration of optical systems using computer generated holograms

    NASA Astrophysics Data System (ADS)

    Coyle, Laura Elizabeth

    As techniques for manufacturing and metrology advance, optical systems are being designed with more complexity than ever before. Given these prescriptions, alignment and calibration can be a limiting factor in their final performance. Computer generated holograms (CGHs) have several unique properties that make them powerful tools for meeting these demanding tolerances. This work will present three novel methods for alignment and calibration of optical systems using computer generated holograms. Alignment methods using CGHs require that the optical wavefront created by the CGH be related to a mechanical datum to locate it space. An overview of existing methods is provided as background, then two new alignment methods are discussed in detail. In the first method, the CGH contact Ball Alignment Tool (CBAT) is used to align a ball or sphere mounted retroreflector (SMR) to a Fresnel zone plate pattern with micron level accuracy. The ball is bonded directly onto the CGH substrate and provides permanent, accurate registration between the optical wavefront and a mechanical reference to locate the CGH in space. A prototype CBAT was built and used to align and bond an SMR to a CGH. In the second method, CGH references are used to align axi-symmetric optics in four degrees of freedom with low uncertainty and real time feedback. The CGHs create simultaneous 3D optical references where the zero order reflection sets tilt and the first diffracted order sets centration. The flexibility of the CGH design can be used to accommodate a wide variety of optical systems and maximize sensitivity to misalignments. A 2-CGH prototype system was aligned multiplied times and the alignment uncertainty was quantified and compared to an error model. Finally, an enhanced calibration method is presented. It uses multiple perturbed measurements of a master sphere to improve the calibration of CGH-based Fizeau interferometers ultimately measuring aspheric test surfaces. The improvement in the

  14. Hydrodynamic optical alignment for microflow cytometry†

    PubMed Central

    Kennedy, Matthew J.; Stelick, Scott J.; Sayam, Lavanya G.; Yen, Andrew; Erickson, David

    2013-01-01

    A microfabricated flow cytometer has been developed that is capable of detecting nearly all of the microparticles in an aqueous suspension. Current design allows for integrated coupling between an optical fiber-based detection system and the particle stream via hydrodynamic focusing. By adjusting the relative flow-rates at the auxiliary inputs of the focusing manifold, the particle stream can be steered out-of-plane relative to the illuminating laser, and similarly the particle stream can be squeezed or expanded. The microfabricated device was constructed in polydimethylsiloxane with cross-sectional microfluidic dimensions of 125 μm × 125 μm. Using the present device and method, fluorescent microparticles in aqueous solution were counted at an absolute counting efficiency of 91 ± 4%. The coefficient of variation of the fluorescence pulse-heights for far-red fluorescent microparticles was 15%. The device exhibited a linear response to fluorescence intensity calibration microparticles as shown by comparison with a commercial cytometer instrument. PMID:21279198

  15. Aligning Optical Fibers by Means of Actuated MEMS Wedges

    NASA Technical Reports Server (NTRS)

    Morgan, Brian; Ghodssi, Reza

    2007-01-01

    Microelectromechanical systems (MEMS) of a proposed type would be designed and fabricated to effect lateral and vertical alignment of optical fibers with respect to optical, electro-optical, optoelectronic, and/or photonic devices on integrated circuit chips and similar monolithic device structures. A MEMS device of this type would consist of a pair of oppositely sloped alignment wedges attached to linear actuators that would translate the wedges in the plane of a substrate, causing an optical fiber in contact with the sloping wedge surfaces to undergo various displacements parallel and perpendicular to the plane. In making it possible to accurately align optical fibers individually during the packaging stages of fabrication of the affected devices, this MEMS device would also make it possible to relax tolerances in other stages of fabrication, thereby potentially reducing costs and increasing yields. In a typical system according to the proposal (see Figure 1), one or more pair(s) of alignment wedges would be positioned to create a V groove in which an optical fiber would rest. The fiber would be clamped at a suitable distance from the wedges to create a cantilever with a slight bend to push the free end of the fiber gently to the bottom of the V groove. The wedges would be translated in the substrate plane by amounts Dx1 and Dx2, respectively, which would be chosen to move the fiber parallel to the plane by a desired amount Dx and perpendicular to the plane by a desired amount Dy. The actuators used to translate the wedges could be variants of electrostatic or thermal actuators that are common in MEMS.

  16. ACCELERATORS: Alignment techniques for DRAGON-I LIA

    NASA Astrophysics Data System (ADS)

    Dai, Zhi-Yong; Xie, Yu-Tong; Li, Hong; Zhang, Wen-Wei; Liu, Yun-Long; Pan, Hai-Feng; Zhang, Lin-Wen; Deng, Jian-Jun

    2009-09-01

    DRAGON-I designed and manufactured by CAEP is a linear induction accelerator which can produce a 20 MeV-3 kA-60 ns electron beam. The high performance required for the machine is determined by the beam quality and thus is greatly dependent on the accelerator alignment. In order to reduce the chromatic effect of the beam, the stretched wire technique has been developed to measure magnetic axes of the cells precisely, and the dipole steering magnets have been equipped into each cell to correct its magnetic axis misalignment. Finally, the laser tracker has been used to examine the installation error of the accelerator. In this paper, different alignment techniques and the primary results are presented and discussed.

  17. Aligning Arrays of Lenses and Single-Mode Optical Fibers

    NASA Technical Reports Server (NTRS)

    Liu, Duncan

    2004-01-01

    A procedure now under development is intended to enable the precise alignment of sheet arrays of microscopic lenses with the end faces of a coherent bundle of as many as 1,000 single-mode optical fibers packed closely in a regular array (see Figure 1). In the original application that prompted this development, the precise assembly of lenses and optical fibers serves as a single-mode spatial filter for a visible-light nulling interferometer. The precision of alignment must be sufficient to limit any remaining wavefront error to a root-mean-square value of less than 1/10 of a wavelength of light. This wavefront-error limit translates to requirements to (1) ensure uniformity of both the lens and fiber arrays, (2) ensure that the lateral distance from the central axis of each lens and the corresponding optical fiber is no more than a fraction of a micron, (3) angularly align the lens-sheet planes and the fiber-bundle end faces to within a few arc seconds, and (4) axially align the lenses and the fiber-bundle end faces to within tens of microns of the focal distance. Figure 2 depicts the apparatus used in the alignment procedure. The beam of light from a Zygo (or equivalent) interferometer is first compressed by a ratio of 20:1 so that upon its return to the interferometer, the beam will be magnified enough to enable measurement of wavefront quality. The apparatus includes relay lenses that enable imaging of the arrays of microscopic lenses in a charge-coupled-device (CCD) camera that is part of the interferometer. One of the arrays of microscopic lenses is mounted on a 6-axis stage, in proximity to the front face of the bundle of optical fibers. The bundle is mounted on a separate stage. A mirror is attached to the back face of the bundle of optical fibers for retroreflection of light. When a microscopic lens and a fiber are aligned with each other, the affected portion of the light is reflected back by the mirror, recollimated by the microscopic lens, transmitted

  18. Optical alignment of electrodes on electrical discharge machines

    NASA Technical Reports Server (NTRS)

    Boissevain, A. G.; Nelson, B. W.

    1972-01-01

    Shadowgraph system projects magnified image on screen so that alignment of small electrodes mounted on electrical discharge machines can be corrected and verified. Technique may be adapted to other machine tool equipment where physical contact cannot be made during inspection and access to tool limits conventional runout checking procedures.

  19. Self-aligning LED-based optical link

    NASA Astrophysics Data System (ADS)

    Shen, Thomas C.; Drost, Robert J.; Rzasa, John R.; Sadler, Brian M.; Davis, Christopher C.

    2016-09-01

    The steady advances in light-emitting diode (LED) technology have motivated the use of LEDs in optical wireless communication (OWC) applications such as indoor local area networks (LANs) and communication between mobile platforms (e.g., robots, vehicles). In contrast to traditional radio frequency (RF) wireless communication, OWC utilizes electromagnetic spectrum that is largely unregulated and unrestricted. OWC communication may be especially useful in RF-denied environments, in which RF communication may be prohibited or undesirable. However, OWC does present some challenges, including the need to maintain alignment between potentially moving nodes. We describe a novel system for link alignment that is composed of a hyperboloidal mirror, camera, and gimbal. The experimental system is able to use the mirror and camera to detect an LED beacon of a neighboring node and estimate its bearing (azimuth and elevation), point the gimbal towards the beacon, and establish an optical link.

  20. Techniques for Optical Interferanemography.

    DTIC Science & Technology

    1985-12-01

    6563 ° .g NOTICE When Government drawings, specifications, or other data are used for any purpose other than in connection with a definitely related...measure the integrated index variation along the line of sight. Consequently, they do not provide spatial resolution and are only adequate in systems that... are symmetric along the line of sight. If spatial resolution is required, a tomographic system can be used but the optical access required exceeds

  1. Optical digital techniques

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Optical interface losses between transmitter-to-fiber interface, connector-to-connector interface, and fiber-to-receiver interface were studied. System effects such as pulse dispersion, risetimes of the sources and detectors, type of fibers used, output power of the sources, and detector sensitivity were considered. Data bus systems such as TEE, Star, and Hybrid were analyzed. The matter of single fiber versus bundle technologies for future avionics systems was considered. The existing data bus system on Space Shuttle was examined and an optical analog was derived for a fiber bundle system, along with the associated power margin. System tests were performed on a feasibility model of a 9-port Star data bus system including BER, star losses, connector losses, etc. The same system was subjected to EMI between the range of 200 Hz to 10 GHz at 20V/m levels. A lightning test was also performed which simulated the conditions similar to those on Space Shuttle. The data bus system was found to be EMI and lightning hard. It is concluded that an optical data bus system is feasible for shuttle orbiter type vehicles.

  2. Alignment and integration of large optical systems based on advanced metrology.

    NASA Astrophysics Data System (ADS)

    Aliverti, M.; Riva, M.; Moschetti, M.; Pariani, G.; Genoni, M.; Zerbi, F. M.

    Optical alignment is a key activity in opto-mechanical system Integration. Traditional techniques require adjustable mounting, driven by optical references that allows the tuning of the optics position along all 6 Degree of Freedom. Nevertheless, the required flexibility imposes reduced stiffness and consequently less stability of the system. The Observatory of Brera (OAB) started few years ago a research activity focused onto the overcoming of this limits exploiting the high metrology performances of Coordinate Measuring Machines (CMM) with the main objectives of relax the manufacturing tolerances and maximize mounting stiffness. Through the T-REX grants, OAB acquired all the instrumentation needed for that activity furthermore considering the ESPRESSO project training and testing also oriented to large scale instrumentation like the E-ELT one. We will present in this paper the definition of the VLTs convergence point and the feasibility study of large mirrors alignment done by mechanical measurements methods. skip=8pt

  3. Survey techniques developed to align stacked beamlines at CEBAF

    SciTech Connect

    Curtis, C.J.; Oren, W.; Tremblay, K.J.

    1994-04-01

    The Continuous Electron Beam Accelerator Facility (CEBAF) in Newport News, Virginia is a new accelerator designed to produce 4 GeV 200 micro-amp continuous wave beams for nuclear physics research. It consists of two superconducting linacs each accelerating electrons by 400 MeV and linked by arcs allowing five pass recirculation. These linacs form the straight sections in a racetrack shaped accelerator contained in over 1.3 km of tunnel. The beam lines will consist of 42 superconducting accelerating cryomodules (in the linacs only), over 400 dipoles, 650 quadrupoles, and 100 sextupoles, most of the which are concentrated in the two arc sections of the machine. It is here that the single beam fine from the linacs is split into five beams of offering energy and transported to the opposite linac where it is recombined into a single beam to again pass through a linac and receive additional acceleration. These recirculation arcs are designed to maintain beam quality through a lattice which is achromatic, isochronous and whose length is equal to a multiple number of RF wavelengths. The short term relative alignment tolerances coupled with the beam fine design reflect the beam quality issues while absolute positioning determines the range of adjustment needed to match the RF phase in the linac segments. The alignment techniques which use a monumented control network as a reference, are designed to position stacked magnets and their support systems to these tolerances. Specialized procedures were tailored from existing hardware and software systems to address each phase or step of the alignment process. This allowed a relatively rapid expansion of alignment services at a new laboratory where surveying support was not seriously addressed until more then one third of the enclosure had been built.

  4. Initial alignment method for free space optics laser beam

    NASA Astrophysics Data System (ADS)

    Shimada, Yuta; Tashiro, Yuki; Izumi, Kiyotaka; Yoshida, Koichi; Tsujimura, Takeshi

    2016-08-01

    The authors have newly proposed and constructed an active free space optics transmission system. It is equipped with a motor driven laser emitting mechanism and positioning photodiodes, and it transmits a collimated thin laser beam and accurately steers the laser beam direction. It is necessary to introduce the laser beam within sensible range of the receiver in advance of laser beam tracking control. This paper studies an estimation method of laser reaching point for initial laser beam alignment. Distributed photodiodes detect laser luminescence at respective position, and the optical axis of laser beam is analytically presumed based on the Gaussian beam optics. Computer simulation evaluates the accuracy of the proposed estimation methods, and results disclose that the methods help us to guide the laser beam to a distant receiver.

  5. Anisotropic picosecond photoconductivity caused by optical alignment of electron momenta in cubic semiconductors

    NASA Astrophysics Data System (ADS)

    Malevich, Y. V.; Adomavičius, R.; Krotkus, A.; Malevich, V. L.

    2014-02-01

    Transient photoconductivity in cubic semiconductors InGaAs and InAs excited by a femtosecond laser pulse in the presence of a uniform dc electric field has been studied with the use of the Monte Carlo simulation by taking into account optical alignment of photoexcited electrons over their momenta. Simulations show that due to the optical alignment effect and energy dependence of the electron mobility, the transient photoconductivity in cubic semiconductors becomes anisotropic during the first few picoseconds after optical excitation. The magnitude of this anisotropy reaches its peak when the excess energy of the optically excited electrons approaches the threshold for the intervalley transfer. It has also been found that when the electrons are excited near the threshold energy for the intervalley transfer, the component of the transient photocurrent directed along the dc field for a short time after the end of the femtosecond optical pulse can become negative. The anisotropy of the transient photoconductivity has been investigated experimentally on (001) InGaAs sample by the optical pump - terahertz-probe technique. Optically induced changes in terahertz pulse amplitude were found to be dependent on the direction of terahertz field relative to the polarization of the optical pump pulse and to the crystallographic axes of the semiconductor. Experimental data have been explained in terms of the transient anisotropic photoconductivity and correlate with the results of the Monte Carlo simulation.

  6. Anisotropic picosecond photoconductivity caused by optical alignment of electron momenta in cubic semiconductors

    SciTech Connect

    Malevich, Y. V. Adomavičius, R.; Krotkus, A.; Malevich, V. L.

    2014-02-21

    Transient photoconductivity in cubic semiconductors InGaAs and InAs excited by a femtosecond laser pulse in the presence of a uniform dc electric field has been studied with the use of the Monte Carlo simulation by taking into account optical alignment of photoexcited electrons over their momenta. Simulations show that due to the optical alignment effect and energy dependence of the electron mobility, the transient photoconductivity in cubic semiconductors becomes anisotropic during the first few picoseconds after optical excitation. The magnitude of this anisotropy reaches its peak when the excess energy of the optically excited electrons approaches the threshold for the intervalley transfer. It has also been found that when the electrons are excited near the threshold energy for the intervalley transfer, the component of the transient photocurrent directed along the dc field for a short time after the end of the femtosecond optical pulse can become negative. The anisotropy of the transient photoconductivity has been investigated experimentally on (001) InGaAs sample by the optical pump - terahertz-probe technique. Optically induced changes in terahertz pulse amplitude were found to be dependent on the direction of terahertz field relative to the polarization of the optical pump pulse and to the crystallographic axes of the semiconductor. Experimental data have been explained in terms of the transient anisotropic photoconductivity and correlate with the results of the Monte Carlo simulation.

  7. A Concept for Zero-Alignment Micro Optical Systems

    SciTech Connect

    DESCOUR, MICHAEL R.; KOLOLUOMA,TERHO; LEVEY,RAVIV; RANTALA,JUHA T.; SHUL,RANDY J.; WARREN,MIAL E.; WILLISON,CHRISTI LEE

    1999-09-16

    We are developing a method of constructing compact, three-dimensional photonics systems consisting of optical elements, e.g., lenses and mirrors, photo-detectors, and light sources, e.g., VCSELS or circular-grating lasers. These optical components, both active and passive, are mounted on a lithographically prepared silicon substrate. We refer to the substrate as a micro-optical table (MOT) in analogy with the macroscopic version routinely used in optics laboratories. The MOT is a zero-alignment, microscopic optical-system concept. The position of each optical element relative to other optical elements on the MOT is determined in the layout of the MOT photomask. Each optical element fits into a slot etched in the silicon MOT. The slots are etched using a high-aspect-ratio silicon etching (HARSE) process. Additional positioning features in each slot's cross-section and complementary features on each optical element permit accurate placement of that element's aperture relative to the MOT substrate. In this paper we present the results of the first fabrication and micro-assembly experiments of a silicon-wafer based MOT. Based on these experiments, estimates of position accuracy are reported. We also report on progress in fabrication of lens elements in a hybrid sol-gel material (HSGM). Diffractive optical elements have been patterned in a 13-micron thick HSGM layer on a 150-micron thick soda-lime glass substrate. The measured ms surface roughness was 20 nm. Finally, we describe modeling of MOT systems using non-sequential ray tracing (NSRT).

  8. Optical alignment of the SPICE EUV imaging spectrometer

    NASA Astrophysics Data System (ADS)

    Rogers, Kevin; Caldwell, Martin; Eccleston, Paul; Griffin, Doug; Greenway, Paul; Fludra, Andrzej; Middleton, Kevin; Tosh, Ian; Richards, Tony; Phillipon, Anne; Schühle, Udo

    2015-09-01

    SPICE is a high resolution imaging spectrometer operating at extreme ultraviolet wavelengths, 70.4 - 79.0 nm and 97.3 - 104.9 nm. It is a facility instrument on the ESA Solar Orbiter mission. SPICE will address the key science goals of Solar Orbiter by providing the quantitative knowledge of the physical state and composition of the plasmas in the solar atmosphere, in particular investigating the source regions of outflows and ejection processes which link the solar surface and corona to the heliosphere. By observing the intensities of selected spectral lines and line profiles, SPICE will derive temperature, density, flow and composition information for the plasmas in the temperature range from 10,000 K to 10MK. The optical components of the instrument consist of an off axis parabolic mirror mounted on a mechanism with a scan range of 8 arc minutes. This allows the rastering of an image of the spectrometer slit, which is interchangeable defining the instrument resolution, on the sky. A concave toroidal variable line space grating disperses, magnifies, and re-images incident radiation onto a pair of photocathode coated microchannel plate image intensifiers, coupled to active pixel sensors. For the instrument to meet the scientific and engineering objectives these components must be tightly aligned with each other and the mechanical interface to the spacecraft. This alignment must be maintained throughout the environmental exposure of the instrument to vibration and thermal cycling seen during launch, and as the spacecraft orbits around the sun. The built alignment is achieved through a mixture of dimensional metrology, autocollimation, interferometry and imaging tests. This paper shall discuss the requirements and the methods of optical alignment.

  9. Elevation angle alignment of quasi optical receiver mirrors of collective Thomson scattering diagnostic by sawtooth measurementsa)

    NASA Astrophysics Data System (ADS)

    Moseev, D.; Meo, F.; Korsholm, S. B.; Bindslev, H.; Furtula, V.; Kantor, M.; Leipold, F.; Michelsen, P. K.; Nielsen, S. K.; Salewski, M.; Stejner, M.

    2012-10-01

    Localized measurements of the fast ion velocity distribution function and the plasma composition measurements are of significant interest for the fusion community. Collective Thomson scattering (CTS) diagnostics allow such measurements with spatial and temporal resolution. Localized measurements require a good alignment of the optical path in the transmission line. Monitoring the alignment during the experiment greatly benefits the confidence in the CTS measurements. An in situ technique for the assessment of the elevation angle alignment of the receiver is developed. Using the CTS diagnostic on TEXTOR without a source of probing radiation in discharges with sawtooth oscillations, an elevation angle misalignment of 0.9° was found with an accuracy of 0.25°.

  10. Polymeric Optical Waveguide with Plastic Optical Fiber Guides for Passive Alignment Fabricated by Hot Embossing

    NASA Astrophysics Data System (ADS)

    Mizuno, Hirotaka; Jordan, Shane; Sugihara, Okihiro; Kaino, Toshikuni; Okamoto, Naomichi; Ohama, Motoshi

    2004-11-01

    The simple fabrication of a passive alignment structure, and the simple connection of polymeric optical waveguides (POWs) and plastic optical fibers (POFs) are presented. Optical waveguides with large core sizes of 500 and 1000 μm were fabricated, and a low propagation loss of 0.21-0.23 dB/cm at 650 nm was achieved in these waveguides. Using a structure with the same core and fiber guide patterns as the master, a passive alignment structure was fabricated easily by hot embossing. POWs directly connected to POFs with passive alignment were realized and the coupling loss from POF to POF through POW was measured to be 1.6 dB at an optimum core width of 900 μm for 980 μm core size POFs.

  11. Optical quantum memory for ultrafast photons using molecular alignment

    NASA Astrophysics Data System (ADS)

    Thekkadath, G. S.; Heshami, K.; England, D. G.; Bustard, P. J.; Sussman, B. J.; Spanner, M.

    2016-11-01

    The absorption of broadband photons in atomic ensembles requires either an effective broadening of the atomic transition linewidth, or an off-resonance Raman interaction. Here, we propose a scheme for a quantum memory capable of storing and retrieving ultrafast photons in an ensemble of two-level atoms using a propagation medium with a time-dependent refractive index generated from aligning an ensemble of gas-phase diatomic molecules. The refractive index dynamics generates an effective longitudinal inhomogeneous broadening of the two-level transition. We numerically demonstrate this scheme for storage and retrieval of a weak pulse as short as 50 fs, with a storage time of up to 20 ps. With additional optical control of the molecular alignment dynamics, the storage time can be extended about one nanosecond leading to time-bandwidth products of order 104. This scheme could in principle be achieved using either a hollow-core fibre or a high-pressure gas cell, in a gaseous host medium comprised of diatomic molecules and a two-level atomic vapour at room temperature.

  12. Theoferometer for High Accuracy Optical Alignment and Metrology

    NASA Technical Reports Server (NTRS)

    Toland, Ronald; Leviton, Doug; Koterba, Seth

    2004-01-01

    The accurate measurement of the orientation of optical parts and systems is a pressing problem for upcoming space missions, such as stellar interferometers, requiring the knowledge and maintenance of positions to the sub-arcsecond level. Theodolites, the devices commonly used to make these measurements, cannot provide the needed level of accuracy. This paper describes the design, construction, and testing of an interferometer system to fill the widening gap between future requirements and current capabilities. A Twyman-Green interferometer mounted on a 2 degree of freedom rotation stage is able to obtain sub-arcsecond, gravity-referenced tilt measurements of a sample alignment cube. Dubbed a 'theoferometer,' this device offers greater ease-of-use, accuracy, and repeatability than conventional methods, making it a suitable 21st-century replacement for the theodolite.

  13. Genetic Algorithm Phase Retrieval for the Systematic Image-Based Optical Alignment Testbed

    NASA Technical Reports Server (NTRS)

    Taylor, Jaime; Rakoczy, John; Steincamp, James

    2003-01-01

    Phase retrieval requires calculation of the real-valued phase of the pupil fimction from the image intensity distribution and characteristics of an optical system. Genetic 'algorithms were used to solve two one-dimensional phase retrieval problem. A GA successfully estimated the coefficients of a polynomial expansion of the phase when the number of coefficients was correctly specified. A GA also successfully estimated the multiple p h e s of a segmented optical system analogous to the seven-mirror Systematic Image-Based Optical Alignment (SIBOA) testbed located at NASA s Marshall Space Flight Center. The SIBOA testbed was developed to investigate phase retrieval techniques. Tiphilt and piston motions of the mirrors accomplish phase corrections. A constant phase over each mirror can be achieved by an independent tip/tilt correction: the phase Conection term can then be factored out of the Discrete Fourier Tranform (DFT), greatly reducing computations.

  14. Optical Device for Converting a Laser Beam into Two Co-aligned but Oppositely Directed Beams

    NASA Technical Reports Server (NTRS)

    Jennings, Donald

    2013-01-01

    Optical systems consisting of a series of optical elements require alignment from the input end to the output end. The optical elements can be mirrors, lenses, sources, detectors, or other devices. Complex optical systems are often difficult to align from end-to-end because the alignment beam must be inserted at one end in order for the beam to traverse the entire optical path to the other end. The ends of the optical train may not be easily accessible to the alignment beam. Typically, when a series of optical elements is to be aligned, an alignment laser beam is inserted into the optical path with a pick-off mirror at one end of the series of elements. But it may be impossible to insert the beam at an end-point. It can be difficult to locate the pick-off mirror at the desired position because there is not enough space, there is no mounting surface, or the location is occupied by a source, detector, or other component. Alternatively, the laser beam might be inserted at an intermediate location (not at an end-point) and sent, first in one direction and then the other, to the opposite ends of the optical system for alignment. However, in this case, alignment must be performed in two directions and extra effort is required to co-align the two beams to make them parallel and coincident, i.e., to follow the same path as an end-to-end beam. An optical device has been developed that accepts a laser beam as input and produces two co-aligned, but counter-propagating beams. In contrast to a conventional alignment laser placed at one end of the optical path, this invention can be placed at a convenient position within the optical train and aligned to send its two beams simultaneously along precisely opposite paths that, taken together, trace out exactly the same path as the conventional alignment laser. This invention allows the user the freedom to choose locations within the optical train for placement of the alignment beam. It is also self-aligned by design and requires

  15. Mechanical blind gap measurement tool for alignment of the JWST Optical Telescope Element

    NASA Astrophysics Data System (ADS)

    Liepmann, Till

    2016-09-01

    This paper describes a novel gap gauge tool that is used to provide an independent check of the James Webb Space Telescope (JWST) Optical Telescope Element (OTE) primary mirror alignment. Making accurate measurements of the mechanical gaps between the OTE mirror segments is needed to verify that the segments were properly aligned relative to each other throughout the integration and test of the 6.6 meter telescope. The gap between the Primary Mirror Segment Assemblies (PMSA) is a sensitive indicator of the relative clocking and decenter. Further, the gap measurements are completely independent of all the other measurements use in the alignment process (e.g. laser trackers and laser radar). The gap measurement is a challenge, however, that required a new approach. Commercial gap measurements tools were investigated; however no suitable solution is available. The challenge of this measurement is due to the required 0.1 mm accuracy, the close spacing of the mirrors segments (approximately 3-9mm), the acute angle between the segment sides (approximately 4 degrees), and the difficult access to the blind gap. Several techniques were considered and tested before selecting the gauge presented here. This paper presents the theory, construction and calibration of the JWST gap gauge that is being used to measure and verify alignment of the OTE primary mirror segments.

  16. Neural nets for aligning optical components in harsh environments: Beam smoothing spatial filter as an example

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.; Krasowski, Michael J.

    1991-01-01

    The goal is to develop an approach to automating the alignment and adjustment of optical measurement, visualization, inspection, and control systems. Classical controls, expert systems, and neural networks are three approaches to automating the alignment of an optical system. Neural networks were chosen for this project and the judgements that led to this decision are presented. Neural networks were used to automate the alignment of the ubiquitous laser-beam-smoothing spatial filter. The results and future plans of the project are presented.

  17. Electronic implementation of optical burst switching techniques

    NASA Astrophysics Data System (ADS)

    Albanese, Ilijc; Darcie, Thomas E.; Ganti, Sudhakar

    2013-10-01

    Extensive research effort is ongoing in energy-efficient Internet-based communications. Optical Flow Switching (OFS) and Optical Burst Switching (OBS) offer potentially efficient alternatives to IP-router-based networks for large data transactions, but significant challenges remain. OFS requires each user to install expensive core network technology, limiting application to highly specialized nodes. OBS can achieve higher scalability but burst assembly/disassembly procedures reduce power efficiency. Finally both OFS and OBS use all-optical switching technologies for which energy efficiency and flexibility remain subject to debate. Our study aims at combining the advantages of both OBS and OFS while avoiding their shortcomings. We consider using a two-way resource reservation protocol for periodic concatenations of large (e.g. 1 Mb) packets or Media Frames (MFs). These chains of MFs (MFCs) are semi-transparent with a periodicity referred to as the "transparency degree". Each MFC is assembled and stored at an end-user machine during the resource reservation procedure and is then switched and buffered electronically along its path. The periodic configuration of each MFC enables interleaving of several chains using buffering only to align the MFs in each MFC in time, largely reducing the buffer requirements with respect to OBS. This periodicity also enables a simple scheduling algorithm to schedule large transactions with minimal control plane processing, achieving link utilization approaching 99.9%. In summary, results indicate that implementing optical burst switching techniques in the electronic domain is a compelling path forward to high-throughput power-efficient networking.

  18. 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.

  19. Holographic Weapons Sight as Crew Optical Alignment Sight

    NASA Technical Reports Server (NTRS)

    Merancy, Nujoud; Dehmlow, Brian; Brazzel, Jack P.

    2011-01-01

    Crew Optical Alignment Sights (COAS) are used by spacecraft pilots to provide a visual reference to a target spacecraft for lateral relative position during rendezvous and docking operations. NASA s Orion vehicle, which is currently under development, has not included a COAS in favor of automated sensors, but the crew office has requested such a device be added for situational awareness and contingency support. The current Space Shuttle COAS was adopted from Apollo heritage, weighs several pounds, and is no longer available for procurement which would make re-use difficult. In response, a study was conducted to examine the possibility of converting a commercially available weapons sight to a COAS for the Orion spacecraft. The device used in this study was the XPS series Holographic Weapon Sight (HWS) procured from L-3 EOTech. This device was selected because the targeting reticule can subtend several degrees, and display a graphic pattern tailored to rendezvous and docking operations. Evaluations of the COAS were performed in both the Orion low-fidelity mockup and rendezvous simulations in the Reconfigurable Operational Cockpit (ROC) by crewmembers, rendezvous engineering experts, and flight controllers at Johnson Space Center. These evaluations determined that this unit s size and mounting options can support proper operation and that the reticule visual qualities are as good as or better than the current Space Shuttle COAS. The results positively indicate that the device could be used as a functional COAS and supports a low-cost technology conversion solution.

  20. Fabrication and optical simulation of vertically aligned silicon nanowires

    NASA Astrophysics Data System (ADS)

    Hossain, M. K.; Salhi, B.; Mukhaimer, A. W.; Al-Sulaiman, F. A.

    2016-10-01

    Silicon nanowires (Si-NWs) have been considered widely as a perfect light absorber with strong evidence of enhanced optical functionalities. Here we report finite-difference time-domain simulations for Si-NWs to elucidate the key factors that determine enhanced light absorption, energy flow behavior, electric field profile, and excitons generation rate distribution. To avoid further complexity, a single Si-NW of cylindrical shape was modeled on c-Si and optimized to elucidate the aforementioned characteristics. Light absorption and energy flow distribution confirmed that Si-NW facilitates to confine photon absorption of several orders of enhancement whereas the energy flow is also distributed along the wire itself. With reference to electric field and excitons generation distribution it was revealed that Si-NW possesses the sites of strongest field distributions compared to those of flat silicon wafer. To realize the potential of Si-NWs-based thin film solar cell, a simple process was adopted to acquire vertically aligned Si-NWs grown on c-Si wafer. Further topographic characterizations were conducted through scanning electron microscope and tunneling electron microscope-coupled energy-dispersive spectroscopy.

  1. New Adaptive Optics Technique Demonstrated

    NASA Astrophysics Data System (ADS)

    2007-03-01

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

  2. Optical alignment and tuning system for the HUST THz-FEL

    NASA Astrophysics Data System (ADS)

    Liu, Xu; Liu, Kaifeng; Qin, Bin; Tan, Ping; Fu, Qiang; Wang, Wei; Pei, Yuanji

    2016-11-01

    A compact FEL oscillator with a radiation wavelength of 30 - 100 μm is proposed by HUST and NSRL. The optical cavity is very sensitive to misalignment errors of the mirror, due to its near-concentric and symmetric structure. The magnetic axis of the undulator, the optical axis of the resonator, and the electron beam propagation axis must all be aligned with high precision for achieving saturated lasing. This paper introduces a high-precision, multi-degree-of-freedom controlled optical alignment system, which has the ability to align in the transverse and longitudinal directions. The alignment tolerances are given by theoretical analysis and numerical simulations with three-dimensional FEL code GENESIS and optical propagation code (OPC). To accomplish optical alignment, two auxiliary HeNe laser systems were introduced. By adjusting the HeNe laser beam spot on the wedge, the optical axis can be aligned to the magnetic axis, and the estimated errors meet the tolerances. Finally, the electron beam will be guided through the hole in the central wedge to complete the transverse alignment. The longitudinal alignment and tuning methods are also described.

  3. Molecular alignment and orientation with a hybrid Raman scattering technique

    NASA Astrophysics Data System (ADS)

    Bustard, Philip J.; Lausten, R.; Sussman, Benjamin J.

    2012-11-01

    We demonstrate a scheme for the preparation of molecular alignment and angular momentum orientation using a hybrid combination of two limits of Raman scattering. First a weak, impulsive pump pulse initializes the system via the nonresonant dynamic Stark effect. Then, having overcome the influence of the vacuum fluctuations, an amplification pulse selectively enhances the initial coherences by transient stimulated Raman scattering, generating alignment and angular momentum orientation of molecular hydrogen. The amplitude and phase of the resulting coherent dynamics are experimentally probed, indicating an amplification factor of 4.5. An analytic theory is developed to model the dynamics.

  4. A Fast and Scalable Kymograph Alignment Algorithm for Nanochannel-Based Optical DNA Mappings

    PubMed Central

    Noble, Charleston; Nilsson, Adam N.; Freitag, Camilla; Beech, Jason P.; Tegenfeldt, Jonas O.; Ambjörnsson, Tobias

    2015-01-01

    Optical mapping by direct visualization of individual DNA molecules, stretched in nanochannels with sequence-specific fluorescent labeling, represents a promising tool for disease diagnostics and genomics. An important challenge for this technique is thermal motion of the DNA as it undergoes imaging; this blurs fluorescent patterns along the DNA and results in information loss. Correcting for this effect (a process referred to as kymograph alignment) is a common preprocessing step in nanochannel-based optical mapping workflows, and we present here a highly efficient algorithm to accomplish this via pattern recognition. We compare our method with the one previous approach, and we find that our method is orders of magnitude faster while producing data of similar quality. We demonstrate proof of principle of our approach on experimental data consisting of melt mapped bacteriophage DNA. PMID:25875920

  5. Alignment control study for the solar optical telescope

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Analysis of the alignment and focus errors than can be tolerated, methods of sensing such errors, and mechanisms to make the necessary corrections were addressed. Alternate approaches and their relative merits were considered. The results of this study indicate that adequate alignment control can be achieved.

  6. Enzyme activity assays within microstructured optical fibers enabled by automated alignment

    PubMed Central

    Warren-Smith, Stephen C.; Nie, Guiying; Schartner, Erik P.; Salamonsen, Lois A.; Monro, Tanya M.

    2012-01-01

    A fluorescence-based enzyme activity assay has been demonstrated within a small-core microstructured optical fiber (MOF) for the first time. To achieve this, a reflection-based automated alignment system has been developed, which uses feedback and piezoelectric actuators to maintain optical alignment. The auto-alignment system provides optical stability for the time required to perform an activity assay. The chosen assay is based on the enzyme proprotein convertase 5/6 (PC6) and has important applications in women’s health. PMID:23243579

  7. Effect of rotational-state-dependent molecular alignment on the optical dipole force

    NASA Astrophysics Data System (ADS)

    Kim, Lee Yeong; Lee, Ju Hyeon; Kim, Hye Ah; Kwak, Sang Kyu; Friedrich, Bretislav; Zhao, Bum Suk

    2016-07-01

    The properties of molecule-optical elements such as lenses or prisms based on the interaction of molecules with optical fields depend in a crucial way on the molecular quantum state and its alignment created by the optical field. Herein, we consider the effects of state-dependent alignment in estimating the optical dipole force acting on the molecules and, to this end, introduce an effective polarizability which takes proper account of molecular alignment and is directly related to the alignment-dependent optical dipole force. We illustrate the significance of including molecular alignment in the optical dipole force by a trajectory study that compares previously used approximations with the present approach. The trajectory simulations were carried out for an ensemble of linear molecules subject to either propagating or standing-wave optical fields for a range of temperatures and laser intensities. The results demonstrate that the alignment-dependent effective polarizability can serve to provide correct estimates of the optical dipole force, on which a state-selection method applicable to nonpolar molecules could be based. We note that an analogous analysis of the forces acting on polar molecules subject to an inhomogeneous static electric field reveals a similarly strong dependence on molecular orientation.

  8. The alignment and isostatic mount bonding technique of the aerospace Cassegrain telescope primary mirror

    NASA Astrophysics Data System (ADS)

    Lin, Wei Cheng; Chang, Shenq-Tsong; Lin, Yu-Chuan; Hsu, Ming-Ying; Chang, Yu-Ting; Chang, Sheng-Hsiung; Huang, Ting-Ming

    2012-10-01

    In order to meet both optical performance and structural stiffness requirements of the aerospace Cassegrain telescope, iso-static mount is used as the interface between the primary mirror and the main plate. This article describes the alignment and iso-static mount bonding technique of the primary mirror by assistance of CMM. The design and assembly of mechanical ground support equipment (MGSE) which reduces the deformation of primary mirror by the gravity effect is also presented. The primary mirror adjusting MGSE consists of X-Y linear translation stages, rotation stage and kinematic constrain platform which provides the function of decenter, orientation, tilt and height adjustment of the posture sequentially. After CMM measurement, the radius of curvature, conic constant, decenter and tilt, etc. will be calculated. According to these results, the posture of the mirror will be adjusted to reduce the tilt by the designed MGSE within 0.02 degrees and the distance deviation from the best fitted profile of mirror to main plate shall be less than 0.01 mm. After that, EC 2216 adhesive is used to bond mirror and iso-static mount. During iso-static mount bonding process, CMM is selected to monitor the relative position deviation of the iso-static mount until the adhesive completely cured. After that, the wave front sensors and strain gauges are used to monitor the strain variation while the iso-static mount mounted in the main plate with the screws by the torque wrench. This step is to prevent deformation of the mirror caused from force of the iso-static mount during the mounting process. In the end, the interferometer is used for the optical performance test with +1G and -1G to check the alignment and bonding technique is well or not.

  9. Optical Alignment of the JWST ISIM to the OTE Simulator (OSIM): Current Concept and Design Studies

    NASA Technical Reports Server (NTRS)

    Frey, Bradley J.; Davila, Pamela S.; Marsh, James M.; Ohl, Raymond G.; Sullivan, Joseph

    2007-01-01

    The James Webb Space Telescope's (JWST) Integrated Science Instrument Module (ISIM) is the scientific payload of the observatory and contai ns four science instruments. During alignment and test of the integrated ISIM (i.e. ISIM + science instruments) at NASA's Goddard Space Fli ght Center (GSFC), the Optical telescope element SIMulator (OSIM) wil l be used to optically stimulate the science instruments to verify their operation and performance. In this paper we present the design of two cryogenic alignment fixtures that will be used to determine and verify the proper alignment of OSIM to ISIM during testing at GSFC. The se fixtures, the Master Alignment Target Fixture (MATF) and the ISIM Alignment Target Fixture (IATF), will provide continuous, 6 degree of freedom feedback to OSIM during initial ambient alignment as well as during cryogenic vacuum testing.

  10. Alignment-independent technique for 3D QSAR analysis.

    PubMed

    Wilkes, Jon G; Stoyanova-Slavova, Iva B; Buzatu, Dan A

    2016-04-01

    Molecular biochemistry is controlled by 3D phenomena but structure-activity models based on 3D descriptors are infrequently used for large data sets because of the computational overhead for determining molecular conformations. A diverse dataset of 146 androgen receptor binders was used to investigate how different methods for defining molecular conformations affect the performance of 3D-quantitative spectral data activity relationship models. Molecular conformations tested: (1) global minimum of molecules' potential energy surface; (2) alignment-to-templates using equal electronic and steric force field contributions; (3) alignment using contributions "Best-for-Each" template; (4) non-energy optimized, non-aligned (2D > 3D). Aggregate predictions from models were compared. Highest average coefficients of determination ranged from R Test (2) = 0.56 to 0.61. The best model using 2D > 3D (imported directly from ChemSpider) produced R Test (2) = 0.61. It was superior to energy-minimized and conformation-aligned models and was achieved in only 3-7 % of the time required using the other conformation strategies. Predictions averaged from models built on different conformations achieved a consensus R Test (2) = 0.65. The best 2D > 3D model was analyzed for underlying structure-activity relationships. For the compound strongest binding to the androgen receptor, 10 substructural features contributing to binding were flagged. Utility of 2D > 3D was compared for two other activity endpoints, each modeling a medium sized data set. Results suggested that large scale, accurate predictions using 2D > 3D SDAR descriptors may be produced for interactions involving endocrine system nuclear receptors and other data sets in which strongest activities are produced by fairly inflexible substrates.

  11. Alignment-independent technique for 3D QSAR analysis

    NASA Astrophysics Data System (ADS)

    Wilkes, Jon G.; Stoyanova-Slavova, Iva B.; Buzatu, Dan A.

    2016-04-01

    Molecular biochemistry is controlled by 3D phenomena but structure-activity models based on 3D descriptors are infrequently used for large data sets because of the computational overhead for determining molecular conformations. A diverse dataset of 146 androgen receptor binders was used to investigate how different methods for defining molecular conformations affect the performance of 3D-quantitative spectral data activity relationship models. Molecular conformations tested: (1) global minimum of molecules' potential energy surface; (2) alignment-to-templates using equal electronic and steric force field contributions; (3) alignment using contributions "Best-for-Each" template; (4) non-energy optimized, non-aligned (2D > 3D). Aggregate predictions from models were compared. Highest average coefficients of determination ranged from R Test 2 = 0.56 to 0.61. The best model using 2D > 3D (imported directly from ChemSpider) produced R Test 2 = 0.61. It was superior to energy-minimized and conformation-aligned models and was achieved in only 3-7 % of the time required using the other conformation strategies. Predictions averaged from models built on different conformations achieved a consensus R Test 2 = 0.65. The best 2D > 3D model was analyzed for underlying structure-activity relationships. For the compound strongest binding to the androgen receptor, 10 substructural features contributing to binding were flagged. Utility of 2D > 3D was compared for two other activity endpoints, each modeling a medium sized data set. Results suggested that large scale, accurate predictions using 2D > 3D SDAR descriptors may be produced for interactions involving endocrine system nuclear receptors and other data sets in which strongest activities are produced by fairly inflexible substrates.

  12. Advanced Adaptive Optics Control Techniques

    DTIC Science & Technology

    1979-01-01

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

  13. Null test fourier domain alignment technique for phase-shifting point diffraction interferometer

    DOEpatents

    Naulleau, Patrick; Goldberg, Kenneth Alan

    2000-01-01

    Alignment technique for calibrating a phase-shifting point diffraction interferometer involves three independent steps where the first two steps independently align the image points and pinholes in rotation and separation to a fixed reference coordinate system, e.g, CCD. Once the two sub-elements have been properly aligned to the reference in two parameters (separation and orientation), the third step is to align the two sub-element coordinate systems to each other in the two remaining parameters (x,y) using standard methods of locating the pinholes relative to some easy to find reference point.

  14. Phase Retrieval Using a Genetic Algorithm on the Systematic Image-Based Optical Alignment Testbed

    NASA Technical Reports Server (NTRS)

    Taylor, Jaime R.

    2003-01-01

    NASA s Marshall Space Flight Center s Systematic Image-Based Optical Alignment (SIBOA) Testbed was developed to test phase retrieval algorithms and hardware techniques. Individuals working with the facility developed the idea of implementing phase retrieval by breaking the determination of the tip/tilt of each mirror apart from the piston motion (or translation) of each mirror. Presented in this report is an algorithm that determines the optimal phase correction associated only with the piston motion of the mirrors. A description of the Phase Retrieval problem is first presented. The Systematic Image-Based Optical Alignment (SIBOA) Testbeb is then described. A Discrete Fourier Transform (DFT) is necessary to transfer the incoming wavefront (or estimate of phase error) into the spatial frequency domain to compare it with the image. A method for reducing the DFT to seven scalar/matrix multiplications is presented. A genetic algorithm is then used to search for the phase error. The results of this new algorithm on a test problem are presented.

  15. Optical Modeling of the Alignment and Test of the NASA James Webb Space Telescope

    NASA Technical Reports Server (NTRS)

    Howard, Joseph M.; Hayden, Bill; Keski-Kuha, Ritva; Feinberg, Lee

    2007-01-01

    Optical modeling challenges of the ground alignment plan and optical test and verification of the NASA James Webb Space Telescope are discussed. Issues such as back-out of the gravity sag of light-weighted mirrors, as well as the use of a sparse-aperture auto-collimating flat system are discussed. A walk-through of the interferometer based alignment procedure is summarized, and sensitivities from the sparse aperture wavefront test are included as examples.'

  16. High finesse optical fiber cavities: optimal alignment and robust stabilization (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Ratschbacher, Lothar; Gallego, Jose; Ghosh, Sutapa; Alavi, Seyed; Alt, Wolfgang; Martinez-Dorantes, Miguel; Meschede, Dieter

    2016-04-01

    Fiber Fabry-Perot cavities, formed by micro-machined mirrors on the end-facets of optical fibers, are used in an increasing number of technical and scientific applications. Some of the most promising areas of application of these optical micro-resonators with high finesse and small mode volume are in the field of quantum communication and information. The resonator-enhanced light-matter interaction, for instance, provide basis for the realization of efficient optical interfaces between stationary matter-based quantum nodes and flying single-photon qubits. To date fiber Fabry-Perot cavities have been successfully applied in experiments interfacing single photons with a wide range of quantum systems, including cold atoms, ions and solid state emitters as well as quantum optomechanical experiments. Here we address some important practical questions that arise during the experimental implementation of high finesse fiber Fabry-Perot cavities: How can optimal fiber cavity alignment be achieved and how can the efficiency of coupling light from the optical fibers to the cavity mode and vice versa be characterized? How should optical fiber cavities be constructed and stabilized to fulfill their potential for miniaturization and integration into robust scientific and technological devices that can operate outside of dedicated laboratory environments in the future? The first two questions we answer with an analytic mode matching calculation that relates the alignment dependent fiber-to-cavity mode-matching efficiency to the easily measurable dip in the reflected light power at the cavity resonance. Our general analysis provides a simple recipe for the optimal alignment of fiber Fabry-Perot cavities and moreover for the first time explains the asymmetry in their reflective line shapes. The latter question we explore by investigating a novel, intrinsically rigid fiber cavity design that makes use of the high passive stability of a monolithic cavity spacer and employs thermal

  17. Underwater Multi-Vehicle Trajectory Alignment and Mapping Using Acoustic and Optical Constraints

    PubMed Central

    Campos, Ricard; Gracias, Nuno; Ridao, Pere

    2016-01-01

    Multi-robot formations are an important advance in recent robotic developments, as they allow a group of robots to merge their capacities and perform surveys in a more convenient way. With the aim of keeping the costs and acoustic communications to a minimum, cooperative navigation of multiple underwater vehicles is usually performed at the control level. In order to maintain the desired formation, individual robots just react to simple control directives extracted from range measurements or ultra-short baseline (USBL) systems. Thus, the robots are unaware of their global positioning, which presents a problem for the further processing of the collected data. The aim of this paper is two-fold. First, we present a global alignment method to correct the dead reckoning trajectories of multiple vehicles to resemble the paths followed during the mission using the acoustic messages passed between vehicles. Second, we focus on the optical mapping application of these types of formations and extend the optimization framework to allow for multi-vehicle geo-referenced optical 3D mapping using monocular cameras. The inclusion of optical constraints is not performed using the common bundle adjustment techniques, but in a form improving the computational efficiency of the resulting optimization problem and presenting a generic process to fuse optical reconstructions with navigation data. We show the performance of the proposed method on real datasets collected within the Morph EU-FP7 project. PMID:26999144

  18. The optical wing aligning device of the Langley Field tunnel

    NASA Technical Reports Server (NTRS)

    Norton, F H; Bacon, D L

    1921-01-01

    Described here is a convenient and accurate method of aligning the wing chord with the airflow. The device was developed to permit rapid and accurate alignment of airfoils and models with the airstream passing through the tunnel. It consists of three main parts: a projector, a reflector, and a target. The arrangement, which is shown in a figure, has proven satisfactory in operation. It is far better than the old method of sighting across a long batten, as the operator of a balance may see the target and correctly judge the accuracy of his alignment. Whereas the old method required two operators and several minutes time to align to within 1/10 degree, this method enables one operator to align a wing to within 1/100 of a degree in a few seconds. This method also has the advantage of being able to measure the angle of the wing while the tunnel is running. Thus, the true angle of incidence is shown.

  19. Optical Omega network: a compact implementation technique

    NASA Astrophysics Data System (ADS)

    Wong, K. W.; Cheng, L. M.

    1995-10-01

    We propose a technique for the compact implementation of an optical Omega network. This technique utilizes the concept that both the perfect-shuffle interconnection and the switching stages can be realized by the same procedures, i.e., duplicate, shift, superimpose, and mask. As a result, a single set of optics is sufficient to realize the whole Omega network in a time-multiplexed recursive manner. Optical setups were designed and a proof-of-principle experiment was performed.

  20. Enhancement Of Optical Registration Signals Through Digital Signal Processing Techniques

    NASA Astrophysics Data System (ADS)

    Cote, Daniel R.; Lazo-Wasem, Jeanne

    1988-01-01

    Alignment and setup of lighography processes has largely been conducted on special test wafers. Actual product level optimization has been limited to manual techniques such as optical verniers. This is especially time consuming and prone to inconsistencies when the registration characteristics of lithographic systems are being measured. One key factor obstructing the use of automated metrology equipment on product level wafers is the inability to discern reliably, metrology features from the background noise and variations in optical registration signals. This is often the case for metal levels such as aluminum and tungsten. This paper discusses methods for enhancement of typical registration signals obtained from difficult semiconductor process levels. Brightfield and darkfield registration signals are obtained using a microscope and a 1024 element linear photodiode array. These signals are then digitized and stored on the hard disk of a computer. The techniques utilized include amplitude selective and adaptive and non-adaptive frequency domain filtering techniques. The effect of each of these techniques upon calculated registration values is analyzed by determining the positional variation of the center location of a two line registration feature. Plots of raw and processed signals obtained are presented as are plots of the power spectral density of ideal metrology feature signal and noise patterns. It is concluded that the proper application of digital signal processing (DSP) techniques to problematic optical registration signals greatly enhances the applicability of automated optical registration measurement techniques to difficult semiconductor process levels.

  1. The deterministic optical alignment of the HERMES spectrograph

    NASA Astrophysics Data System (ADS)

    Gers, Luke; Staszak, Nicholas

    2014-07-01

    The High Efficiency and Resolution Multi Element Spectrograph (HERMES) is a four channel, VPH-grating spectrograph fed by two 400 fiber slit assemblies whose construction and commissioning has now been completed at the Anglo Australian Telescope (AAT). The size, weight, complexity, and scheduling constraints of the system necessitated that a fully integrated, deterministic, opto-mechanical alignment system be designed into the spectrograph before it was manufactured. This paper presents the principles about which the system was assembled and aligned, including the equipment and the metrology methods employed to complete the spectrograph integration.

  2. Automated alignment of a reconfigurable optical system using focal-plane sensing and Kalman filtering.

    PubMed

    Fang, Joyce; Savransky, Dmitry

    2016-08-01

    Automation of alignment tasks can provide improved efficiency and greatly increase the flexibility of an optical system. Current optical systems with automated alignment capabilities are typically designed to include a dedicated wavefront sensor. Here, we demonstrate a self-aligning method for a reconfigurable system using only focal plane images. We define a two lens optical system with 8 degrees of freedom. Images are simulated given misalignment parameters using ZEMAX software. We perform a principal component analysis on the simulated data set to obtain Karhunen-Loève modes, which form the basis set whose weights are the system measurements. A model function, which maps the state to the measurement, is learned using nonlinear least-squares fitting and serves as the measurement function for the nonlinear estimator (extended and unscented Kalman filters) used to calculate control inputs to align the system. We present and discuss simulated and experimental results of the full system in operation.

  3. OAJ 2.6m survey telescope: optical alignment and on-sky evaluation of IQ performances

    NASA Astrophysics Data System (ADS)

    Lousberg, Gregory P.; Bastin, Christian; Moreau, Vincent; Pirnay, Olivier; Flebus, Carlo; Chueca, Sergio; Iñiguez, César; Ederoclite, Alessandro; Ramió, Héctor V.; Cenarro, A. Javier

    2016-08-01

    AMOS has recently completed the alignment campaign of the 2.6m telescope for the Observatorio Astrofisico de Javalambre (OAJ). AMOS developed an innovative alignment technique for wide field-of-view telescopes that has been successfully implemented on the OAJ 2.6m telescope with the active support of the team of CEFCA (Centro de Estudios de Física del Cosmos de Aragón). The alignment relies on two fundamental techniques: (1) the wavefront-curvature sensing (WCS) for the evaluation of the telescope aberrations at arbitrary locations in the focal plane, and (2) the comafree point method for the adjustment of the position of the secondary mirror (M2) and of the focal plane (FP). The alignment campaign unfolds in three steps: (a) analysis of the repeatability of the WCS measurements, (b) assessment of the sensitivity of telescope wavefront error to M2 and FP position adjustments, and (c) optical alignment of the telescope. At the end of the campaign, seeing-limited performances are demonstrated in the complete focal plane. With the help of CEFCA team, the image quality of the telescope are investigated with a lucky-imaging method. Image sizes of less than 0.3 arcsec FWHM are obtained, and this excellent image quality is observed over the complete focal plane.

  4. Genetic Algorithm Phase Retrieval for the Systematic Image-Based Optical Alignment Testbed

    NASA Technical Reports Server (NTRS)

    Rakoczy, John; Steincamp, James; Taylor, Jaime

    2003-01-01

    A reduced surrogate, one point crossover genetic algorithm with random rank-based selection was used successfully to estimate the multiple phases of a segmented optical system modeled on the seven-mirror Systematic Image-Based Optical Alignment testbed located at NASA's Marshall Space Flight Center.

  5. Review of Techniques for In-Flight Transfer Alignment

    DTIC Science & Technology

    1992-06-01

    accessible literature during the last three decades. Kalman filtering techniques based on lincarised dynamics dominated in the literature of the subject...DESIGN OF A KALMAN FILTER ........... ..................... 2 2.1 Linear estimation................................ 2 9. "ie r se...5 2.4 Reduclig the order of Kalman filter ............ ...................... 5 2.5 ’,’zmpression ot data

  6. Stitching Techniques Advance Optics Manufacturing

    NASA Technical Reports Server (NTRS)

    2010-01-01

    Because NASA depends on the fabrication and testing of large, high-quality aspheric (nonspherical) optics for applications like the James Webb Space Telescope, it sought an improved method for measuring large aspheres. Through Small Business Innovation Research (SBIR) awards from Goddard Space Flight Center, QED Technologies, of Rochester, New York, upgraded and enhanced its stitching technology for aspheres. QED developed the SSI-A, which earned the company an R&D 100 award, and also developed a breakthrough machine tool called the aspheric stitching interferometer. The equipment is applied to advanced optics in telescopes, microscopes, cameras, medical scopes, binoculars, and photolithography."

  7. Computer-aided alignment method of optical lens with high accuracy

    NASA Astrophysics Data System (ADS)

    Xing, Song; Hou, Xiao-hua; Zhang, Xue-min; Ji, Bin-dong

    2016-09-01

    With the development of space and aviation industry, the optical systems with high resolution and better imaging quality are required. According to the alignment technical process, the factors of every step which have big influence to the imaging quality are analyzed. It is detected that the micro-stress assembly of the optical unit and the high co-axial precision of the entire optical system are the two important factors which are supposed to determine how well the imaging quality of the optical system is; also the technical methods are discussed to ensure these two factors from the engineering view. The reflective interference testing method to measure the surface figure and the transitive interference testing method to measure the wave aberration of the optical unit are combined to ensure the micro-stress assembly of the optical unit, so it will not bring astigmatism to the whole system imaging quality. Optical alignment machining and precision alignment are combined to ensure the high co-axial precision of the optical system. An optical lens of high accuracy is assembled by using these methods; the final wave aberration of optical lens is 0.022λ.

  8. Fabrication, Testing, Coating and Alignment of Fast Segmented Optics

    DTIC Science & Technology

    2006-05-25

    mirror segment, a 100 mm thick Zerodur mirror blank was purchased from Schott. Figure 2 shows the segment and its support for polishing and testing in...Polishing large off-axis segments of fast primary mirrors 2. Testing large segments in an off-axis geometry 3. Alignment of multiple segments of a large... mirror 4. Coatings that reflect high-intensity light without distorting the substrate These technologies are critical because of several unique

  9. Field-aligned electric currents and their measurement by the incoherent backscatter technique

    NASA Technical Reports Server (NTRS)

    Bauer, P.; Cole, K. D.; Lejeume, G.

    1975-01-01

    Field aligned electric currents flow in the magnetosphere in many situations of fundamental geophysical interest. It is shown here that the incoherent backscatter technique can be used to measure these currents when the plasma line can be observed. The technique provides a ground based means of measuring these currents which complements the rocket and satellite ones.

  10. All-optical signal processing technique for secure optical communication

    NASA Astrophysics Data System (ADS)

    Qian, Feng-chen; Su, Bing; Ye, Ya-lin; Zhang, Qian; Lin, Shao-feng; Duan, Tao; Duan, Jie

    2015-10-01

    Secure optical communication technologies are important means to solve the physical layer security for optical network. We present a scheme of secure optical communication system by all-optical signal processing technique. The scheme consists of three parts, as all-optical signal processing unit, optical key sequence generator, and synchronous control unit. In the paper, all-optical signal processing method is key technology using all-optical exclusive disjunction (XOR) gate based on optical cross-gain modulation effect, has advantages of wide dynamic range of input optical signal, simple structure and so on. All-optical XOR gate composed of two semiconductor optical amplifiers (SOA) is a symmetrical structure. By controlling injection current, input signal power, delay and filter bandwidth, the extinction ratio of XOR can be greater than 8dB. Finally, some performance parameters are calculated and the results are analyzed. The simulation and experimental results show that the proposed method can be achieved over 10Gbps optical signal encryption and decryption, which is simple, easy to implement, and error-free diffusion.

  11. Manufacture, alignment and measurement for a reflective triplet optics in imaging spectrometer

    NASA Astrophysics Data System (ADS)

    Yuan, Liyin; He, Zhiping; Wang, Yueming; Lv, Gang

    2016-09-01

    Reflective triplet (RT) optics is an optical form with decenters and tilts of all the three mirrors. It can be used in spectrometer as collimator and reimager to get fine optical and spectral performances. To alleviate thermal and assembly stress deformation, opto-mechanical integrated design suggests that as with all the machine elements and the mainframe, the mirrors substrates are aluminum. All the mirrors are manufactured by single-point diamond turning technology and measured by interferometer or profilometer. Because of retro-reflection by grating or prism and reimaging away from the object field, solo three mirrors optical path of RT has some aberrations. So its alignment and measurement needs an aberration corrected measuring optical system with auxiliary plane and sphere mirrors and in which the RT optics used in four pass. Manufacture, alignment and measurement for a RT optics used in long wave infrared grating spectrometer is discussed here. We realized the manufacture, alignment and test for the RT optics of a longwave infrared spectromter by CMM and interferometer. Wavefront error test by interferometer and surface profiles measured by profilometer indicate that performances of the manufactured mirrors exceed the requirements. Interferogram of the assembled RT optics shows that wavefront error rms is less than 0.0493λ@10.6μm vs design result 0.0207λ.

  12. Novel optical and ultrasound techniques for biomedicine

    NASA Astrophysics Data System (ADS)

    Esenaliev, Rinat O.

    2003-10-01

    In this paper we present recent results of our studies on the development and tests of: 1) optoacoustic monitoring of cerebral blood oxygenation; 2) optical coherence tomography for accurate measurement of tissue optical properties; and 3) ultrasound-enhanced anti-cancer drug delivery. Major experimental results obtained in vitro and in vivo with the use of these techniques are reported and discussed.

  13. Automated alignment of optical components for high-power diode lasers

    NASA Astrophysics Data System (ADS)

    Brecher, C.; Pyschny, N.; Haag, S.; Guerrero Lule, V.

    2012-03-01

    Despite major progress in developing brilliant laser sources a huge potential for cost reductions can be found in simpler setups and automated assembly processes, especially for large volume applications. In this presentation, a concept for flexible automation in optics assembly is presented which is based on standard micro assembly systems with relatively large workspace and modular micromanipulators to enhance the system with additional degrees of freedom and a very high motion resolution. The core component is a compact flexure-based micromanipulator especially designed for the alignment of micro optical components which will be described in detail. The manipulator has been applied in different scenarios to develop and investigate automated alignment processes. This paper focuses on the automated alignment of fast axis collimation (FAC) lenses which is a crucial step during the production of diode lasers. The handling and positioning system, the measuring arrangement for process feedback during active alignment as well as the alignment strategy will be described. The fine alignment of the FAC lens is performed with the micromanipulator under concurrent analysis of the far and the near field intensity distribution. An optimization of the image processing chains for the alignment of a FAC in front of a diode bar led to cycle times of less than 30 seconds. An outlook on other applications and future work regarding the development of automated assembly processes as well as new ideas for flexible assembly systems with desktop robots will close the talk.

  14. Alignment method of optical registration for multi-channel CCD camera

    NASA Astrophysics Data System (ADS)

    Xin, Jia; Yue, Guo

    2016-10-01

    The mapping satellite is use of the multichip CCD assemble technology to meet the precision landscape positioning requirements. The size of a single CCD cannot meet the requirements of modern optical system. High cost and special technology are required for the resolution. In order to apply space camera to the measurement in large field of view and high resolution, the technology of optical assembly with several CCD is discussed. And a reflector based butting system was adopted. To extend the field of view, an optical butting system is proposed. Aiming at the problems of vignette and decline of modulation transfer function caused by butting, a reflector based butting system which has nine mirrors was investigated. This paper introduced the structure design of a long array and the principle of optical butting. The basic idea of this system is to split the optical image into several parts, so that they can be detected by different sensors. The mirror is used in conventional imaging system; divide the optical image into two parts. To eliminate the vignette distortion caused by the optical system and keep high signal to noise ratio, the sensors receiving the two focal image parts are placed with a little overlapping so that they can compensate each other. In order to ensure the key techniques of mirror location accuracy, a new alignment method was proposed about locating conversation components, mainly aimed at enhancing assembly accuracy of linear array CCD.A high quality image can be obtained by butting the two image parts. Its principle, methods of adjusting and testing as well as the structure of focal plane are described. The assembly with nine TDICCDs is finished on the facility which is composed of a long work-distance microscope and a precise X-Y rail, using the method in which the mechanical adjusting is applied. Compared with convention system, this method can satisfy the linearity accuracy and overlapping pixels tolerance of 0.2 detector pixel sizes. And can

  15. Real-time Optical Alignment and Diagnostic System (ROADS)

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The ultimate and most frequent usage of ROADS will be the alignment of subassemblies (collector and collimator) prior to their installation in a chamber. The system as designed has inherent associated capabilities well applied to acceptance testing of the No. 4 mirror, prediction of in-chamber performance, generation of a catalog of test results and other data, providing data for the plotting of isointensity lines, and other applications which are discussed. The ROADS system will collect, process, display, analyze, and retain data as required for components, partial subassemblies, complete subassemblies, complete modules, and multimodular arrays.

  16. Alignment techniques required by precise measurement of effective focal length

    NASA Technical Reports Server (NTRS)

    Wise, T. D.

    1980-01-01

    The characteristics of false color imagery produced by instrumentation on earth resource mapping satellites are examined. The spatial fidelity of the imagery is dependent upon the geometric accuracy (GA) and the band-to-band registration (BBR) with which the telescope instrument is assembled. BBR and GA require knowledge of telescope effective focal length (EFL) to one part in 10,000 in order that the next generation of earth mappers be able to carry out their missions. The basis for this level of precision is briefly considered, and a description is given of the means by which such precise EFL measurements have been carried out. Attention is given to accuracy requirements, the technique used to measure effective focal length, possible sources of error in the EFL measurement, approaches for eliminating errors, and the results of the efforts to control measurement errors in EFL determinations.

  17. Large Volume, Optical and Opto-Mechanical Metrology Techniques for ISIM on JWST

    NASA Technical Reports Server (NTRS)

    Hadjimichael, Theo

    2015-01-01

    The final, flight build of the Integrated Science Instrument Module (ISIM) element of the James Webb Space Telescope is the culmination of years of work across many disciplines and partners. This paper covers the large volume, ambient, optical and opto-mechanical metrology techniques used to verify the mechanical integration of the flight instruments in ISIM, including optical pupil alignment. We present an overview of ISIM's integration and test program, which is in progress, with an emphasis on alignment and optical performance verification. This work is performed at NASA Goddard Space Flight Center, in close collaboration with the European Space Agency, the Canadian Space Agency, and the Mid-Infrared Instrument European Consortium.

  18. Initial Navigation Alignment of Optical Instruments on GOES-R

    NASA Technical Reports Server (NTRS)

    Isaacson, Peter J.; DeLuccia, Frank J.; Reth, Alan D.; Igli, David A.; Carter, Delano R.

    2016-01-01

    Post-launch alignment errors for the Advanced Baseline Imager (ABI) and Geospatial Lightning Mapper (GLM) on GOES-R may be too large for the image navigation and registration (INR) processing algorithms to function without an initial adjustment to calibration parameters. We present an approach that leverages a combination of user-selected image-to-image tie points and image correlation algorithms to estimate this initial launch-induced offset and calculate adjustments to the Line of Sight Motion Compensation (LMC) parameters. We also present an approach to generate synthetic test images, to which shifts and rotations of known magnitude are applied. Results of applying the initial alignment tools to a subset of these synthetic test images are presented. The results for both ABI and GLM are within the specifications established for these tools, and indicate that application of these tools during the post-launch test (PLT) phase of GOES-R operations will enable the automated INR algorithms for both instruments to function as intended.

  19. Optical multiple object tracking techniques

    NASA Astrophysics Data System (ADS)

    Liu, Hua-Kuang; Chao, Tien-Hsin

    1989-02-01

    Two multichannel multiple-object tracking techniques are reviewed. In the diffraction grating technique, the input scene is picked up by a TV camera and imaged onto a liquid-crystal light valve (LCLV), and the output side of the light valve is illuminated with a suitably polarized and collimated coherent laser beam to yield a reflected beam with polarization modulated according to the intensity of the incoherent input. This reflected beam passes through a beam splitter cube and an analyzer, resulting in an intensity modulated coherent image. An array of spectrum islands containing the information of the input appears after crossing a contact screen/lens combination. In the multiple-focus hololens technique, the scene of moving objects is sent into the LCTVSLM through a camera; a collimated laser beam is incident upon the LCTV screen; a low-pass filter is inserted between the LCTVSLM and the hololens for the removal of the high order diffractions due to the grid structure of the LCTV. The feasibility of the LCTVSLM and multiple-focus hololens technique is demonstrated.

  20. Optical multiple object tracking techniques

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang; Chao, Tien-Hsin

    1989-01-01

    Two multichannel multiple-object tracking techniques are reviewed. In the diffraction grating technique, the input scene is picked up by a TV camera and imaged onto a liquid-crystal light valve (LCLV), and the output side of the light valve is illuminated with a suitably polarized and collimated coherent laser beam to yield a reflected beam with polarization modulated according to the intensity of the incoherent input. This reflected beam passes through a beam splitter cube and an analyzer, resulting in an intensity modulated coherent image. An array of spectrum islands containing the information of the input appears after crossing a contact screen/lens combination. In the multiple-focus hololens technique, the scene of moving objects is sent into the LCTVSLM through a camera; a collimated laser beam is incident upon the LCTV screen; a low-pass filter is inserted between the LCTVSLM and the hololens for the removal of the high order diffractions due to the grid structure of the LCTV. The feasibility of the LCTVSLM and multiple-focus hololens technique is demonstrated.

  1. Precision assembly and alignment of large optic modules for the National Ignition Facility

    SciTech Connect

    Hurst, P.; Grasz, E.

    1998-05-12

    The National Ignition Facility (NIF), currently under design and construction at Lawrence Livermore National Laboratory (LLNL), will be the world`s biggest laser. The optics for the multipass, 192-beam, high-power, neodymium-glass laser will be assembled and aligned in the NIF Optics Assembly Building (OAB), adjacent to the huge Laser and Target Area Building (LTAB), where they will be installed. To accommodate the aggressive schedule for initial installation and activation, rapid assembly and alignment of large aperture optics into line replaceable units (LRUs) will occur through the use of automated handling, semi-autonomous operations, and strict protocols. The OAB will have to maintain rigorous cleanliness levels, achieve both commonality and versatility to handle the various optic types, and allow for just-in-time processing and delivery of the optics into the LTAB without undoing their strict cleanliness and precise alignment. This paper describes the Project`s design philosophy of modularity and hardware commonality and presents the many design challenges encountered. It also describes how, by using a mixture of commercially available and newly designed equipment, we have developed unique systems for assembly and alignment, inspection and verification, and LRU loading and transfer.

  2. Optical and x-ray alignment approaches for off-plane reflection gratings

    NASA Astrophysics Data System (ADS)

    Allured, Ryan; Donovan, Benjamin D.; DeRoo, Casey T.; Marlowe, Hannah R.; McEntaffer, Randall L.; Tutt, James H.; Cheimets, Peter N.; Hertz, Edward; Smith, Randall K.; Burwitz, Vadim; Hartner, Gisela; Menz, Benedikt

    2015-09-01

    Off-plane reflection gratings offer the potential for high-resolution, high-throughput X-ray spectroscopy on future missions. Typically, the gratings are placed in the path of a converging beam from an X-ray telescope. In the off-plane reflection grating case, these gratings must be co-aligned such that their diffracted spectra overlap at the focal plane. Misalignments degrade spectral resolution and effective area. In-situ X-ray alignment of a pair of off-plane reflection gratings in the path of a silicon pore optics module has been performed at the MPE PANTER beamline in Germany. However, in-situ X-ray alignment may not be feasible when assembling all of the gratings required for a satellite mission. In that event, optical methods must be developed to achieve spectral alignment. We have developed an alignment approach utilizing a Shack-Hartmann wavefront sensor and diffraction of an ultraviolet laser. We are fabricating the necessary hardware, and will be taking a prototype grating module to an X-ray beamline for performance testing following assembly and alignment.

  3. Techniques for Solution- Assisted Optical Contacting

    NASA Technical Reports Server (NTRS)

    DeVine, Glenn; Ware, Brent; Wuchenich, Danielle M.; Spero, Robert E.; Klipstein, William M.; McKenzie, Kirk

    2012-01-01

    A document discusses a solution-assisted contacting technique for optical contacting. An optic of surface flatness Lambda/20 was successfully contacted with one of moderate surface quality, or Lambda/4. Optics used were both ultra-low expansion (ULE) glass (Lambda/4 and Lambda/20) and fused silica (Lambda/20). A stainless steel template of the intended interferometer layout was designed and constructed with three contact points per optic. The contact points were all on a common side of the template. The entire contacting jig was tilted at about 30 . Thus, when the isopropanol was applied, each optic slid due to gravity, resting on the contact points. All of the contacting was performed in a relatively dusty laboratory. A number of successful contacts were achieved where up to two or three visible pieces of dust could be seen. These were clearly visible due to refraction patterns between the optic and bench. On a number of optics, the final step of dropping isopropyl between the surfaces was repeated until a successful contact was achieved. The new procedures realized in this work represent a simplification for optical contacting in the laboratory. They will both save time and money spent during the contacting process, and research and development phases. The techniques outlined are suitable for laboratory experiments, research, and initial development stages.

  4. Tear film measurement by optical reflectometry technique.

    PubMed

    Lu, Hui; Wang, Michael R; Wang, Jianhua; Shen, Meixiao

    2014-02-01

    Evaluation of tear film is performed by an optical reflectometer system with alignment guided by a galvanometer scanner. The reflectometer system utilizes optical fibers to deliver illumination light to the tear film and collect the film reflectance as a function of wavelength. Film thickness is determined by best fitting the reflectance-wavelength curve. The spectral reflectance acquisition time is 15 ms, fast enough for detecting film thickness changes. Fast beam alignment of 1 s is achieved by the galvanometer scanner. The reflectometer was first used to evaluate artificial tear film on a model eye with and without a contact lens. The film thickness and thinning rate have been successfully quantified with the minimum measured thickness of about 0.3 μm. Tear films in human eyes, with and without a contact lens, have also been evaluated. A high-contrast spectral reflectance signal from the precontact lens tear film is clearly observed, and the thinning dynamics have been easily recorded from 3.69 to 1.31 μm with lipid layer thickness variation in the range of 41 to 67 nm. The accuracy of the measurement is better than ±0.58% of the film thickness at an estimated tear film refractive index error of ±0.001. The fiber-based reflectometer system is compact and easy to handle.

  5. Tear film measurement by optical reflectometry technique

    PubMed Central

    Lu, Hui; Wang, Michael R.; Wang, Jianhua; Shen, Meixiao

    2014-01-01

    Abstract. Evaluation of tear film is performed by an optical reflectometer system with alignment guided by a galvanometer scanner. The reflectometer system utilizes optical fibers to deliver illumination light to the tear film and collect the film reflectance as a function of wavelength. Film thickness is determined by best fitting the reflectance-wavelength curve. The spectral reflectance acquisition time is 15 ms, fast enough for detecting film thickness changes. Fast beam alignment of 1 s is achieved by the galvanometer scanner. The reflectometer was first used to evaluate artificial tear film on a model eye with and without a contact lens. The film thickness and thinning rate have been successfully quantified with the minimum measured thickness of about 0.3 μm. Tear films in human eyes, with and without a contact lens, have also been evaluated. A high-contrast spectral reflectance signal from the precontact lens tear film is clearly observed, and the thinning dynamics have been easily recorded from 3.69 to 1.31 μm with lipid layer thickness variation in the range of 41 to 67 nm. The accuracy of the measurement is better than ±0.58% of the film thickness at an estimated tear film refractive index error of ±0.001. The fiber-based reflectometer system is compact and easy to handle. PMID:24500519

  6. The extreme ultraviolet imager of solar orbiter: optical design and alignment scheme

    NASA Astrophysics Data System (ADS)

    Halain, J.-P.; Mazzoli, A.; Meining, S.; Rochus, P.; Renotte, E.; Auchère, F.; Schühle, U.; Delmotte, F.; Dumesnil, C.; Philippon, A.; Mercier, R.; Hermans, A.

    2015-09-01

    The Extreme Ultraviolet Imager (EUI) is one of the remote sensing instruments on-board the Solar Orbiter mission. It will provide dual-band full-Sun images of the solar corona in the extreme ultraviolet (17.1 nm and 30.4 nm), and high resolution images of the solar disk in both extreme ultraviolet (17.1 nm) and vacuum ultraviolet (Lyman-alpha 121.6 nm). The EUI optical design takes heritage of previous similar instruments. The Full Sun Imager (FSI) channel is a single mirror Herschel design telescope. The two High Resolution Imager (HRI) channels are based on a two-mirror optical refractive scheme, one Ritchey-Chretien and one Gregory optical design for the EUV and the Lyman-alpha channels, respectively. The spectral performances of the EUI channels are obtained thanks to dedicated mirror multilayer coatings and specific band-pass filters. The FSI channel uses a dual-band mirror coating combined with aluminum and zirconium band-pass filters. The HRI channels use optimized band-pass selection mirror coatings combined with aluminum band-pass filters and narrow band interference filters for Lyman-alpha. The optical performances result from accurate mirror manufacturing tolerances and from a two-step alignment procedure. The primary mirrors are first co-aligned. The HRI secondary mirrors and focal planes positions are then adjusted to have an optimum interferometric cavity in each of these two channels. For that purpose a dedicated alignment test setup has been prepared, composed of a dummy focal plane assembly representing the detector position. Before the alignment on the flight optical bench, the overall alignment method has been validated on the Structural and Thermal Model, on a dummy bench using flight spare optics, then on the Qualification Model to be used for the system verification test and qualifications.

  7. Compact Optical Technique for Streak Camera Calibration

    SciTech Connect

    Curt Allen; Terence Davies; Frans Janson; Ronald Justin; Bruce Marshall; Oliver Sweningsen; Perry Bell; Roger Griffith; Karla Hagans; Richard Lerche

    2004-04-01

    The National Ignition Facility is under construction at the Lawrence Livermore National Laboratory for the U.S. Department of Energy Stockpile Stewardship Program. Optical streak cameras are an integral part of the experimental diagnostics instrumentation. To accurately reduce data from the streak cameras a temporal calibration is required. This article describes a technique for generating trains of precisely timed short-duration optical pulses that are suitable for temporal calibrations.

  8. The impact of camera optical alignments on weak lensing measures for the Dark Energy Survey

    SciTech Connect

    Antonik, M. L.; Bacon, D. J.; Bridle, S.; Doel, P.; Brooks, D.; Worswick, S.; Bernstein, G.; Bernstein, R.; DePoy, D.; Flaugher, B.; Frieman, J. A.; Gladders, M.; Gutierrez, G.; Jain, B.; Jarvis, M.; Kent, S. M.; Lahav, O.; Parker, S. -. J.; Roodman, A.; Walker, A. R.

    2013-04-10

    Telescope point spread function (PSF) quality is critical for realizing the potential of cosmic weak lensing observations to constrain dark energy and test general relativity. In this paper, we use quantitative weak gravitational lensing measures to inform the precision of lens optical alignment, with specific reference to the Dark Energy Survey (DES). We compute optics spot diagrams and calculate the shear and flexion of the PSF as a function of position on the focal plane. For perfect optical alignment, we verify the high quality of the DES optical design, finding a maximum PSF contribution to the weak lensing shear of 0.04 near the edge of the focal plane. However, this can be increased by a factor of approximately 3 if the lenses are only just aligned within their maximum specified tolerances. We calculate the E- and B-mode shear and flexion variance as a function of the decentre or tilt of each lens in turn. We find tilt accuracy to be a few times more important than decentre, depending on the lens considered. Finally, we consider the compound effect of decentre and tilt of multiple lenses simultaneously, by sampling from a plausible range of values of each parameter. We find that the compound effect can be around twice as detrimental as when considering any one lens alone. Furthermore, this combined effect changes the conclusions about which lens is most important to align accurately. For DES, the tilt of the first two lenses is the most important.

  9. Alignment and Integration Techniques for Mirror Segment Pairs on the Constellation X Telescope

    NASA Technical Reports Server (NTRS)

    Hadjimichael, Theo; Lehan, John; Olsen, Larry; Owens, Scott; Saha, Timo; Wallace, Tom; Zhang, Will

    2007-01-01

    We present the concepts behind current alignment and integration techniques for testing a Constellation-X primary-secondary mirror segment pair in an x-ray beam line test. We examine the effects of a passive mount on thin glass x-ray mirror segments, and the issues of mount shape and environment on alignment. We also investigate how bonding and transfer to a permanent housing affects the quality of the final image, comparing predicted results to a full x-ray test on a primary secondary pair.

  10. Tolerancing, alignment and test of the Transiting Exoplanet Survey Satellite (TESS) optical assembly

    NASA Astrophysics Data System (ADS)

    Primeau, Brian; Balonek, Gregory; MacDonald, Robert; Chrisp, Michael; Chesbrough, Christian; Andre, James; Clark, Kristin

    2016-09-01

    The Transiting Exoplanet Survey Satellite (TESS) will carry four visible waveband seven-element refractive f/1.4 lenses, each with a 34 degree diagonal field of view. This paper describes the tolerancing, assembly and alignment methods developed during the build of the TESS Risk Reduction Unit optical system. Lens assembly tolerances were derived from a sensitivity analysis using an image quality metric customized for mission performance. The optomechanical design consists of a two-stage lens housing that provides access for active alignment of each lens using a Trioptics OptiCentric measurement system. Thermal stresses and alignment shifts are mitigated by mounting the optics with cast RTV silicone spacers into individually aligned bezels, and custom fixtures were developed to aid in RTV bonding with reduced alignment error. The lens assembly was tested interferometrically over the field of view at room temperature and results were used to successfully predict lens performance and compensator adjustments and detector shim thickness for the -75C operational temperature and pressure.

  11. A comparison between using incoherent or coherent sources to align and test an adaptive optical telescope

    NASA Technical Reports Server (NTRS)

    Anderson, Richard

    1994-01-01

    The concept in the initial alignment of the segmented mirror adaptive optics telescope called the phased array mirror extendable large aperture telescope (Pamela) is to produce an optical transfer function (OTF) which closely approximates the diffraction limited value which would correspond to a system pupil function that is unity over the aperture and zero outside. There are differences in the theory of intensity measurements between coherent and incoherent radiation. As a result, some of the classical quantities which describe the performance of an optical system for incoherent radiation can not be defined for a coherent field. The most important quantity describing the quality of an optical system is the OTF and for a coherent source the OTF is not defined. Instead a coherent transfer function (CTF) is defined. The main conclusion of the paper is that an incoherent collimated source and not a collimated laser source is preferred to calibrate the Hartmann wavefront sensor (WFS) of an aligned adaptive optical system. A distant laser source can be used with minimum problems to correct the system for atmospheric turbulence. The collimation of the HeNe laser alignment source can be improved by using a very small pin hole in the spatial filter so only the central portion of the beam is transmitted and the beam from the filter is nearly constant in amplitude. The size of this pin hole will be limited by the sensitivity of the lateral effect diode (LEDD) elements.

  12. Well-aligned cellulose nanofiber-reinforced polyvinyl alcohol composite film: Mechanical and optical properties.

    PubMed

    Cai, Jie; Chen, Jingyao; Zhang, Qian; Lei, Miao; He, Jingren; Xiao, Anhong; Ma, Chengjie; Li, Sha; Xiong, Hanguo

    2016-04-20

    Uniaxially aligned cellulose nanofibers (CNFs), which are fabricated by electrospinning of cellulose acetate derived from bamboo cellulose (B-CA) followed by deacetylation, were used as reinforcements to make optically transparent composite films. We examined the effects of B-CA concentration and electrospinning parameters (e.g. spinning distance, and collection speed) on fiber morphology and orientation, which act on mechanical-to-optical properties of the CNFs-reinforced composites. Consequently, the resultant composite film exhibits high visible-light transmittance even with high fiber content, as well as improved mechanical properties. The understanding obtained from this study may facilitate the development of novel nanofibrous materials for various optical uses.

  13. Combining calcium imaging with other optical techniques.

    PubMed

    Canepari, Marco; Zecevic, Dejan; Vogt, Kaspar E; Ogden, David; De Waard, Michel

    2013-12-01

    Ca(2+) imaging is a commonly used approach for measuring Ca(2+) signals at high spatial resolution. The method is often combined with electrode recordings to correlate electrical and chemical signals or to investigate Ca(2+) signals following an electrical stimulation. To obtain information on electrical activity at the same spatial resolution, Ca(2+) imaging must be combined with membrane potential imaging. Similarly, stimulation of subcellular compartments requires photostimulation. Thus, combining Ca(2+) imaging with an additional optical technique facilitates the study of a number of physiological questions. The aim of this article is to introduce some basic principles regarding the combination of Ca(2+) imaging with other optical techniques. We discuss the design of the optics, the design of experimental protocols, the optical characteristics of Ca(2+) indicators used in combination with an optical probe, and the affinity of the Ca(2+) indicator in relation to the type of measurement. This information will enable the reader to devise an optimal strategy for combined optical experiments.

  14. Micro-vision servo control of a multi-axis alignment system for optical fiber assembly

    NASA Astrophysics Data System (ADS)

    Chen, Weihai; Yu, Fei; Qu, Jianliang; Chen, Wenjie; Zhang, Jianbin

    2017-04-01

    This paper describes a novel optical fiber assembly system featuring a multi-axis alignment function based on micro-vision feedback control. It consists of an active parallel alignment mechanism, a passive compensation mechanism, a micro-gripper and a micro-vision servo control system. The active parallel alignment part is a parallelogram-based design with remote-center-of-motion (RCM) function to achieve precise rotation without fatal lateral motion. The passive mechanism, with five degrees of freedom (5-DOF), is used to implement passive compensation for multi-axis errors. A specially designed 1-DOF micro-gripper mounted onto the active parallel alignment platform is adopted to grasp and rotate the optical fiber. A micro-vision system equipped with two charge-coupled device (CCD) cameras is introduced to observe the small field of view and obtain multi-axis errors for servo feedback control. The two CCD cameras are installed in an orthogonal arrangement—thus the errors can be easily measured via the captured images. Meanwhile, a series of tracking and measurement algorithms based on specific features of the target objects are developed. Details of the force and displacement sensor information acquisition in the assembly experiment are also provided. An experiment demonstrates the validity of the proposed visual algorithm by achieving the task of eliminating errors and inserting an optical fiber to the U-groove accurately.

  15. Dental diagnostics using optical coherence techniques

    SciTech Connect

    Nathel, H.; Colston, B.; Armitage, G.

    1994-11-15

    Optical radiation can be used for diagnostic purposes in oral medicine. However, due to the turbid, amorphous, and inhomogeneous nature of dental tissue conventional techniques used to transilluminate materials are not well suited to dental tissues. Optical coherence techniques either in the time- of frequency-domain offer the capabilities of discriminating scattered from unscattered light, thus allowing for imaging through turbid tissue. Currently, using optical time-domain reflectometry we are able to discriminate specular from diffuse reflections occurring at tissue boundaries. We have determined the specular reflectivity of enamel and dentin to be approximately 6.6 x 10{sup -5} and 1.3 x 10{sup -6}, respectively. Implications to periodontal imaging will be discussed.

  16. Using MapleSim to model a six-strut kinematic mount for aligning optical components

    NASA Astrophysics Data System (ADS)

    Duffy, Alan; Yates, Brian; Hu, Yongfeng

    2011-09-01

    Ray tracing simulations are often performed for an ideal situation of perfect alignment, but it is usually necessary to move optical components for various reasons. The mounts that hold these components can be complicated and modeling their motion is vital to understanding how they affect the performance of the system. This paper examines the behaviour of a six-strut kinematic mount using MapleSim to investigate and understand precisely how a mirror pole moves with its mount and quantify any cross-coupled motion that may occur during actuator adjustments. This positional information can be used to mitigate errors, improve ray tracing results, and assist in alignment.

  17. Experimental Estimation of CLASP Spatial Resolution: Results of the Instrument's Optical Alignment

    NASA Technical Reports Server (NTRS)

    Giono, Gabrial; Katsukawa, Yukio; Ishikawa, Ryoko; Narukage, Noriyuki; Bando, Takamasa; Kano, Ryohei; Suematsu, Yoshinori; Kobayashi, Ken; Winebarger, Amy; Auchere, Frederic

    2015-01-01

    The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) is a sounding-rocket experiment currently being built at the National Astronomical Observatory of Japan. This instrument aims to probe for the first time the magnetic field strength and orientation in the solar upper-chromosphere and lower-transition region. CLASP will measure the polarization of the Lyman-Alpha line (121.6nm) with an unprecedented accuracy, and derive the magnetic field information through the Hanle effect. Although polarization accuracy and spectral resolution are crucial for the Hanle effect detection, spatial resolution is also important to get reliable context image via the slit-jaw camera. As spatial resolution is directly related with the alignment of optics, it is also a good way of ensuring the alignment of the instrument to meet the scientific requirement. This poster will detail the experiments carried out to align CLASP's optics (telescope and spectrograph), as both part of the instrument were aligned separately. The telescope was aligned in double-pass mode, and a laser interferometer (He-Ne) was used to measure the telescope's wavefront error (WFE). The secondary mirror tilt and position were adjusted to remove comas and defocus aberrations from the WFE. Effect of gravity on the WFE measurement was estimated and the final WFE derived in zero-g condition for CLASP telescope will be presented. In addition, an estimation of the spot shape and size derived from the final WFE will also be shown. The spectrograph was aligned with a custom procedure: because Ly-??light is absorbed by air, the spectrograph's off-axis parabolic mirrors were aligned in Visible Light (VL) using a custom-made VL grating instead of the flight Ly-? grating. Results of the alignment in Visible Light will be shown and the spot shape recorded with CCDs at various position along the slit will be displayed. Results from both alignment experiment will be compared to the design requirement, and will be combined in

  18. Alignment performance comparison between MFR and MDCO for a TMA optical system

    NASA Astrophysics Data System (ADS)

    Kang, Hyukmo; Oh, Eunsong; Kim, Sug-Whan

    2015-09-01

    In this study, we performed alignment state estimation simulations and compared the performance of two Computer Aided Alignment (hereafter CAA) algorithms i.e. `Merit Function Regression (MFR)' and `Multiple Design Configuration Optimization (MDCO)' for a TMA optical system. The former minimizes the merit function using multi-field wavefront error measurements from single configuration, while the latter minimizes the merit function using single-field measured wavefront error from multiple configurations. The optical system used is an unobscured three-mirror anastigmat (TMA) optical system of 70mm in diameter, and F/5.0. It is designed for an unmanned aerial vehicle for coastal water remote sensing. The TMA consists of two aspherical mirrors, a spherical mirror and a flat folding mirror. Based on the sensitivity analysis, we set the tilt x, y of tertiary mirror as a compensator, and not considered decenter of tertiary mirror because of its spherical characteristic. For the simulation, we introduced Gaussian distribution of initial misalignment to M3. It has the mean value of zero and standard deviation of 0.5 mrad. The initial simulation result of alignment state estimation shows that both algorithms can meet the alignment requirement, λ/10 RMS WFE at 633nm. However, when we includes measurement noise, the simulation result of MFR shows greater standard deviation in RMS WFE than that of MDCO. As for the measurement, the MDCO requires single on-axis field while the MFR requires multiple fields, we concluded that the MDCO is more practical method to align the off-axis TMA optics than MFR.

  19. Novel theory for propagation of tilted Gaussian beam through aligned optical system

    NASA Astrophysics Data System (ADS)

    Xia, Lei; Gao, Yunguo; Han, Xudong

    2017-03-01

    A novel theory for tilted beam propagation is established in this paper. By setting the propagation direction of the tilted beam as the new optical axis, we establish a virtual optical system that is aligned with the new optical axis. Within the first order approximation of the tilt and off-axis, the propagation of the tilted beam is studied in the virtual system instead of the actual system. To achieve more accurate optical field distributions of tilted Gaussian beams, a complete diffraction integral for a misaligned optical system is derived by using the matrix theory with angular momentums. The theory demonstrates that a tilted TEM00 Gaussian beam passing through an aligned optical element transforms into a decentered Gaussian beam along the propagation direction. The deviations between the peak intensity axis of the decentered Gaussian beam and the new optical axis have linear relationships with the misalignments in the virtual system. ZEMAX simulation of a tilted beam through a thick lens exposed to air shows that the errors between the simulation results and theoretical calculations of the position deviations are less than 2‰ when the misalignments εx, εy, εx', εy' are in the range of [-0.5, 0.5] mm and [-0.5, 0.5]°.

  20. Optical Measurement Technique for Space Column Characterization

    NASA Technical Reports Server (NTRS)

    Barrows, Danny A.; Watson, Judith J.; Burner, Alpheus W.; Phelps, James E.

    2004-01-01

    A simple optical technique for the structural characterization of lightweight space columns is presented. The technique is useful for determining the coefficient of thermal expansion during cool down as well as the induced strain during tension and compression testing. The technique is based upon object-to-image plane scaling and does not require any photogrammetric calibrations or computations. Examples of the measurement of the coefficient of thermal expansion are presented for several lightweight space columns. Examples of strain measured during tension and compression testing are presented along with comparisons to results obtained with Linear Variable Differential Transformer (LVDT) position transducers.

  1. Implement of Digital Moire technique on DSP for alignment of partial compensation interferometer

    NASA Astrophysics Data System (ADS)

    Tian, Yuhan; QunHao; YaoHu; Wang, Shaopu; Li, Tengfei; Wang, Jingxian

    2016-01-01

    Digital Moiré technique is adopted in partial compensation interferometer (PCI) for high-precision testing of figure error of the aspheric surfaces. The figure error of the measured aspheric is obtained by a series of calculation with the real interferogram and ideal interferograms generated by computer. The dense interference fringes at the exit pupil make it difficult to align the PCI. On the contrary, digital Moire fringes composed from real and ideal interferograms are sparse and corresponding to the figure error of the measured aspheric, making it easier to align the PCI. Generally, digital Moire technique is processed on the computer, resulting in slow processing speed and difficult display in real time. Digital Signal Processor (DSP) can be used to implement digital Moire technique and display digital Moire fringes in real time with its powerful processing capacity. In this paper, digital Moire technique is implemented on the TMS320C6455 DSP. The hardware system consists of a DSP module, a CCD camera and a monitor. Finally we experimentally obtain the digital Moire image, and further analyze how to align the PCI theoretically.

  2. An efficient and accurate molecular alignment and docking technique using ab initio quality scoring

    PubMed Central

    Füsti-Molnár, László; Merz, Kenneth M.

    2008-01-01

    An accurate and efficient molecular alignment technique is presented based on first principle electronic structure calculations. This new scheme maximizes quantum similarity matrices in the relative orientation of the molecules and uses Fourier transform techniques for two purposes. First, building up the numerical representation of true ab initio electronic densities and their Coulomb potentials is accelerated by the previously described Fourier transform Coulomb method. Second, the Fourier convolution technique is applied for accelerating optimizations in the translational coordinates. In order to avoid any interpolation error, the necessary analytical formulas are derived for the transformation of the ab initio wavefunctions in rotational coordinates. The results of our first implementation for a small test set are analyzed in detail and compared with published results of the literature. A new way of refinement of existing shape based alignments is also proposed by using Fourier convolutions of ab initio or other approximate electron densities. This new alignment technique is generally applicable for overlap, Coulomb, kinetic energy, etc., quantum similarity measures and can be extended to a genuine docking solution with ab initio scoring. PMID:18624561

  3. Method for auto-alignment of digital optical phase conjugation systems based on digital propagation

    PubMed Central

    Jang, Mooseok; Ruan, Haowen; Zhou, Haojiang; Judkewitz, Benjamin; Yang, Changhuei

    2014-01-01

    Optical phase conjugation (OPC) has enabled many optical applications such as aberration correction and image transmission through fiber. In recent years, implementation of digital optical phase conjugation (DOPC) has opened up the possibility of its use in biomedical optics (e.g. deep-tissue optical focusing) due to its ability to provide greater-than-unity OPC reflectivity (the power ratio of the phase conjugated beam and input beam to the OPC system) and its flexibility to accommodate additional wavefront manipulations. However, the requirement for precise (pixel-to-pixel matching) alignment of the wavefront sensor and the spatial light modulator (SLM) limits the practical usability of DOPC systems. Here, we report a method for auto-alignment of a DOPC system by which the misalignment between the sensor and the SLM is auto-corrected through digital light propagation. With this method, we were able to accomplish OPC playback with a DOPC system with gross sensor-SLM misalignment by an axial displacement of up to~1.5 cm, rotation and tip/tilt of ~5∘, and in-plane displacement of ~5 mm (dependent on the physical size of the sensor and the SLM). Our auto-alignment method robustly achieved a DOPC playback peak-to-background ratio (PBR) corresponding to more than ~30 % of the theoretical maximum. As an additional advantage, the auto-alignment procedure can be easily performed at will and, as such, allows us to correct for small mechanical drifts within the DOPC systems, thus overcoming a previously major DOPC system vulnerability. We believe that this reported method for implementing robust DOPC systems will broaden the practical utility of DOPC systems. PMID:24977504

  4. Metrology optical power budgeting in SIM using statistical analysis techniques

    NASA Astrophysics Data System (ADS)

    Kuan, Gary M.

    2008-07-01

    The Space Interferometry Mission (SIM) is a space-based stellar interferometry instrument, consisting of up to three interferometers, which will be capable of micro-arc second resolution. Alignment knowledge of the three interferometer baselines requires a three-dimensional, 14-leg truss with each leg being monitored by an external metrology gauge. In addition, each of the three interferometers requires an internal metrology gauge to monitor the optical path length differences between the two sides. Both external and internal metrology gauges are interferometry based, operating at a wavelength of 1319 nanometers. Each gauge has fiber inputs delivering measurement and local oscillator (LO) power, split into probe-LO and reference-LO beam pairs. These beams experience power loss due to a variety of mechanisms including, but not restricted to, design efficiency, material attenuation, element misalignment, diffraction, and coupling efficiency. Since the attenuation due to these sources may degrade over time, an accounting of the range of expected attenuation is needed so an optical power margin can be book kept. A method of statistical optical power analysis and budgeting, based on a technique developed for deep space RF telecommunications, is described in this paper and provides a numerical confidence level for having sufficient optical power relative to mission metrology performance requirements.

  5. Metrology Optical Power Budgeting in SIM Using Statistical Analysis Techniques

    NASA Technical Reports Server (NTRS)

    Kuan, Gary M

    2008-01-01

    The Space Interferometry Mission (SIM) is a space-based stellar interferometry instrument, consisting of up to three interferometers, which will be capable of micro-arc second resolution. Alignment knowledge of the three interferometer baselines requires a three-dimensional, 14-leg truss with each leg being monitored by an external metrology gauge. In addition, each of the three interferometers requires an internal metrology gauge to monitor the optical path length differences between the two sides. Both external and internal metrology gauges are interferometry based, operating at a wavelength of 1319 nanometers. Each gauge has fiber inputs delivering measurement and local oscillator (LO) power, split into probe-LO and reference-LO beam pairs. These beams experience power loss due to a variety of mechanisms including, but not restricted to, design efficiency, material attenuation, element misalignment, diffraction, and coupling efficiency. Since the attenuation due to these sources may degrade over time, an accounting of the range of expected attenuation is needed so an optical power margin can be book kept. A method of statistical optical power analysis and budgeting, based on a technique developed for deep space RF telecommunications, is described in this paper and provides a numerical confidence level for having sufficient optical power relative to mission metrology performance requirements.

  6. Diagnostic apparatus and method for use in the alignment of one or more laser means onto a fiber optics interface

    DOEpatents

    Johnson, S.A.; Shannon, R.R.

    1985-01-18

    Diagnostic apparatus for use in determining the proper alignment of a plurality of laser beams onto a fiber optics interface is disclosed. The apparatus includes a lens assembly which serves two functions, first to focus a plurality of laser beams onto the fiber optics interface, and secondly to reflect and image the interface using scattered light to a monitor means. The monitor means permits indirect observation of the alignment or focusing of the laser beams onto the fiber optics interface.

  7. Diagnostic apparatus and method for use in the alignment of one or more laser means onto a fiber optics interface

    DOEpatents

    Johnson, Steve A.; Shannon, Robert R.

    1987-01-01

    Diagnostic apparatus for use in determining the proper alignment of a plurality of laser beams onto a fiber optics interface is disclosed. The apparatus includes a lens assembly which serves two functions, first to focus a plurality of laser beams onto the fiber optics interface, and secondly to reflect and image the interface using scattered light to a monitor means. The monitor means permits indirect observation of the alignment or focusing of the laser beams onto the fiber optics interface.

  8. Surface reformation and electro-optical characteristics of liquid crystal alignment layers using ion beam irradiation

    SciTech Connect

    Oh, Byeong-Yun; Lee, Kang-Min; Kim, Byoung-Yong; Kim, Young-Hwan; Han, Jin-Woo; Han, Jeong-Min; Lee, Sang-Keuk; Seo, Dae-Shik

    2008-09-15

    The surface modification characteristics of liquid crystal (LC) alignment layers irradiated with various argon (Ar) ion beam (IB) energies were investigated as a substitute for rubbing technology. Various pretilt angles were created on the IB-irradiated polyimide (PI) surfaces after IB irradiation, but the Ar ions did not alter the morphology on the PI surface, indicating that the pretilt angle was not due to microgrooves. The chemical bonding states of the IB-irradiated PI surfaces were analyzed in detail by x-ray photoelectron spectroscopy to verify the compositional behavior for the LC alignment. Chemical structure analysis showed that the alignment ability of LCs was due to the preferential reorientation of the carbon network due to the breaking of C=O double bonds in the imide ring parallel to the incident IB direction. The potential of applying nonrubbing technology to display devices was further supported by the superior electro-optical characteristics compared to rubbed PI.

  9. Time-varying gyrocompass alignment for fiber-optic-gyro inertial navigation system with large misalignment angle

    NASA Astrophysics Data System (ADS)

    Ben, Yueyang; Li, Qian; Zhang, Yi; Huo, Liang

    2014-09-01

    Conventional strapdown gyrocompass alignment methods are based on the assumption that the fiber-optic-gyro inertial navigation system has a small azimuth misalignment angle. A large azimuth misalignment angle would lead to an extension of the alignment duration. A time-varying gyrocompass alignment method to solve this problem is provided. An appropriate parameter setting is given for the gyrocompass alignment with a large misalignment angle. Also, a proper protocol for a parametric switch is derived. Simulation and trail results show that the proposed method has better alignment performance than conventional ones, as the system has large misalignment angles.

  10. A MEMS-based device used for alignment and manipulation of MLL x-ray focusing optics

    NASA Astrophysics Data System (ADS)

    Xu, Weihe; Lauer, Kenneth; Yan, Hui; Millanovic, Veljko; Nazaretski, Evgeny; Brookhaven Natl Lab Team; Mirrorcle Technologies, Inc. Team

    2015-03-01

    Multilayer Laue lenses (MLLs) X-ray microscopy is a powerful tool used for materials research. To push the spatial resolution of x-ray microscopy studies below 10 nm the system needs to be compact and rigid. Applications of MEMS based tip-tilt stages used for alignment and manipulation of nanofocusing optics is a promising route to achieve high stability. In this work, we report characterization and stability testing of a MEMS device suitable for manipulation of nanofocusing optics. We developed two closed-loop circuits implemented in a MEMS tip-tilt device utilizing capacitive and laser interferometry techniques. Test results demonstrate better than 10 mille-degree resolution when using capacitive sensors and better than 0.8 mille-degree resolution when using interferometry sensing respectively.

  11. Active alignment and vibration control system for a large airborne optical system

    NASA Astrophysics Data System (ADS)

    Kienholz, David A.

    2000-04-01

    Airborne optical or electro-optical systems may be too large for all elements to be mounted on a single integrating structure, other than the aircraft fuselage itself. An active system must then be used to maintain the required alignment between elements. However the various smaller integrating structures (benches) must still be isolated from high- frequency airframe disturbances that could excite resonances outside the bandwidth of the alignment control system. The combined active alignment and vibration isolation functions must be performed by flight-weight components, which may have to operate in vacuum. A testbed system developed for the Air Force Airborne Laser program is described. The payload, a full-scale 1650-lb simulated bench, is mounted in six degrees- of-freedom to a vibrating platform by a set of isolator- actuators. The mounts utilize a combination of pneumatics and magnetics to perform the dual functions of low-frequency alignment and high-frequency isolation. Test results are given and future directions for development are described.

  12. Magnetic field-aligned electric field acceleration and the characteristics of the optical aurora

    NASA Technical Reports Server (NTRS)

    Christensen, A. B.; Lyons, L. R.; Hecht, J. H.; Sivjee, G. G.; Meier, R. R.

    1987-01-01

    The long-recognized association of brighter aurora with more deeply penetrating, and hence more energetic, electrons is examined. Using the Knight (1973) relation between the magnetic-field-aligned current density and potential drop (derived from the theory of single-particle motion in the presence of a magnetic-field-aligned electric field), an approximate expression relating the energy flux of the precipitating electrons over discrete aurora and the mean particle energy is derived. This expression is used in conjunction with an auroral optical excitation and emission model to specify the dependence of the red/blue ratio of auroral optical emissions on the brightness of the aurora. It is shown that the quantitative predictions of the discrete auroral theory are in accord with observations of the aurora.

  13. Optical control of plasmonic heating effects using reversible photo-alignment of nematic liquid crystals

    NASA Astrophysics Data System (ADS)

    Palermo, Giovanna; Cataldi, Ugo; De Sio, Luciano; Bürgi, Thomas; Tabiryan, Nelson; Umeton, Cesare

    2016-11-01

    We demonstrate and characterize an optical control of the plasmonic heat delivered by a monolayer substrate of gold nanoparticles, obtained by modulating the effective refractive index of the neighboring dielectric medium. The effect, which exploits the dependence of the nematic liquid crystal (NLC) refractive index on the molecular director orientation, is realized by using a polarization dependent, light-induced molecular reorientation of a thin film of photo-alignment layer that the NLC is in contact with. For a suitable alignment, plasmonic pumping intensity values ranging from 0.25 W/cm2 to 6.30 W/cm2 can induce up to 17.4 °C temperature variations in time intervals of the order of seconds. The reversibility of the optically induced NLC molecular director orientation enables an active control of the plasmonic photo-induced heat.

  14. Application of holographic optical techniques to bulk memory.

    NASA Technical Reports Server (NTRS)

    Anderson, L. K.

    1971-01-01

    Current efforts to exploit the spatial redundancy and built-in imaging of holographic optical techniques to provide high information densities without critical alignment and tight mechanical tolerances are reviewed. Read-write-erase in situ operation is possible but is presently impractical because of limitations in available recording media. As these are overcome, it should prove feasible to build holographic bulk memories with mechanically replaceable hologram plates featuring very fast (less than 2 microsec) random access to large (greater than 100 million bit) data blocks and very high throughput (greater than 500 Mbit/sec). Using volume holographic storage it may eventually be possible to realize random-access mass memories which require no mechanical motion and yet provide very high capacity.

  15. Quadrant-division technique for differential sensitivity optical beam measurement

    NASA Astrophysics Data System (ADS)

    Hii, K. U.

    2016-11-01

    A novel method for optical beam collimation measurement is presented. The collimating lens is utilized in four parts of quadrants with the beam aligned onto the first quadrant and configured to pass the subsequent quadrants. This allows the test beam to pass the collimating lens for four times. Subsequently, the test beam is reversed to achieve a total number of eight passes. Hence, for a defocus introduced, the collimation state of the test beam can be evaluated at the amplification of eight. The evaluation of the test beam is performed based on the approach of collimation testing using lateral shearing interferometer. The proposed technique provides a differential collimation sensitivity for accurate setting of a highly collimated beam.

  16. Surface Wear Measurement Using Optical Correlation Technique

    NASA Astrophysics Data System (ADS)

    Acinger, Kresimir

    1983-12-01

    The coherent optical correlation technique was applied for measuring the surface wear of a tappet (part of car engine), worn by friction with the camshaft. It was found that maximum correlation intensity decays exponentially with the number of wear cycles (i.e. camshaft revolutions). Tappets of the same make have an identical rate of correlation decay. Tappets of different makes have different rates of correlation decay which are in agreement with observed long term wear.

  17. Optical development system lab alignment solutions for the ICESat-2 ATLAS instrument

    NASA Astrophysics Data System (ADS)

    Evans, T.

    The ATLAS Instrument for the ICESat-2 mission at NASA's Goddard Space Flight Center requires an alignment test-bed to prove out new concepts. The Optical Development System (ODS) lab was created to test prototype models of individual instrument components to simulate how they will act as a system. The main ICESat-2 instrument is the Advanced Topographic Laser Altimeter System (ATLAS). It measures ice elevation by transmitting laser pulses, and collecting the reflection in a telescope. Because the round trip time is used to calculate distance, alignment between the outgoing transmitter beam and the incoming receiver beams are critical. An automated closed loop monitoring control system is currently being tested at the prototype level to prove out implementation for the final spacecraft. To achieve an error of less than 2 micro-radians, an active deformable mirror was used to correct the lab wave front from the collimated “ ground reflection” beam. The lab includes a focal plane assembly set up, a one meter diameter collimator optic, and a 0.8 meter flight spare telescope for alignment. ATLAS prototypes and engineering models of transmitter and receiver optics and sub-systems are brought in to develop and integrate systems as well as write procedures to be used in integration and testing. By having a fully integrated system with prototypes and engineering units, lessons can be learned before flight designs are finalized.

  18. Imaging techniques with refractive beam shaping optics

    NASA Astrophysics Data System (ADS)

    Laskin, Alexander; Laskin, Vadim

    2012-10-01

    Applying of the refractive beam shapers in real research optical setups as well as in industrial installations requires very often manipulation of a final laser spot size. In many cases this task can be easily solved by using various imaging optical layouts presuming creating an image of a beam shaper output aperture. Due to the unique features of the refractive beam shapers of field mapping type, like flat wave front and low divergence of the collimated resulting beam with flattop or another intensity profile, there is a freedom in building of various imaging systems with using ordinary optical components, including off-the-shelf ones. There will be considered optical layouts providing high, up to 1/200×, de-magnifying factors, combining of refractive beam shapers like πShaper with scanning systems, building of relay imaging systems with extended depth of field. These optical layouts are widely used in such laser technologies like drilling holes in PCB, welding, various micromachining techniques with galvo-mirror scanning, interferometry and holography, various SLM-based applications. Examples of real implementations and experimental results will be presented as well.

  19. Optical and structural properties of amorphous Se x Te100- x aligned nanorods

    NASA Astrophysics Data System (ADS)

    Al-Agel, Faisal A.

    2013-12-01

    In the present work, we report studies on optical and structural phenomenon in as-deposited thin films composed of aligned nanorods of amorphous Se x Te100- x ( x = 3, 6, 9, and 12). In structural studies, field emission scanning electron microscopic (FESEM) images suggest that these thin films contain high yield of aligned nanorods. These nanorods show a completely amorphous nature, which is verified by X-ray diffraction patterns of these thin films. Optical studies include the measurement of spectral dependence of absorption, reflection, and transmission of these thin films, respectively. On the basis of optical absorption data, a direct optical band gap is observed. This observation of a direct optical band gap in these nanorods is interesting as chalcogenides normally show an indirect band gap, and due to this reason, these materials could not become very popular for semiconducting devices. Therefore, this is an important report and will open up new directions for the application of these materials in semiconducting devices. The value of this optical band gap is found to decrease with the increase in selenium (Se) concentration. The reflection and absorption data are employed to estimate the values of optical constants (extinction coefficient ( k) and refractive index ( n)). From the spectral dependence of these optical constants, it is found that the values of refractive index ( n) increase, whereas the values of extinction coefficient ( k) decrease with the increase in photon energy. The real and imaginary parts of dielectric constants calculated with the values of extinction coefficient ( k) and refractive index ( n), are found to vary with photon energy and dopant concentration.

  20. Coherent Fiber Optic Coupling Techniques For Downhole Imaging Camerasl

    NASA Astrophysics Data System (ADS)

    Cameron, George R.

    1987-10-01

    Cameras used to monitor underground nuclear testing experiments are subjected to a variety of harsh conditions which must be accounted for during the design phase. Since experiments are buried several thousand feet below ground, reliability is of foremost concern. Many of the cameras designed at Lawrence Livermore Laboratory contain coherent fiber optic components such as microchannel plate image intensifiers, fiber optic reducers, and diode or CCD imaging arrays. Coupling of these components calls for hardware which will maintain precise contact and alignment in conditions of high vibration, large thermal transition, and high humidity. In addition, the hardware must be easily assembled by untrained technical personnel under less than ideal conditions (windy, dusty, rainy, etc.). A high speed imaging camera based upon a Fairchild CCD array chip was designed at Livermore in 1984. Problems in coupling the array window to a fiber optic reducer were aggravated by mounting of the array chip rigidly to the main video circuit board. A new array chip daughter board, attached by flat ribbon cable and supported by a spring loaded lever combination was designed to overcome the problem. The hardware did not increase the overall size of the existing camera and increased the unit cost by less than 1 K$. The design of this hardware will be discussed along with useful techniques for designers of cameras used in harsh environments.

  1. Study cell invasion by optical techniques

    NASA Astrophysics Data System (ADS)

    Yang, Ying; Hoban, Paul R.; Sule-Suso, Joseph; Holley, Sarah; El Haj, Alicia J.; Bahrami, Fariba; Wang, Ruikang K.

    2006-02-01

    Cancer is a world-wide health problem associated with an increasing death rate. The mechanisms of how normal cells transform into cancer cells are not fully understood. Intensive investigations have been undertaken to identify genes whose unregulated expression are involved in this process. In this study, we have grown, on collagen gel, adherent mouse embryo fibroblasts (MEFs) knocked out for Cyl-1 (MEF Cyl1-/-) which have been transfected with the human proto-oncogene cyclin D1 (CCND1) under the control of an inducible expression system. CCND1 expression can be regulated in the fibroblasts via the presence of an inducer, isopropyl β-D-Thiogalactopyranoside (IPTG). In the absence of IPTG, CCND1 expression is silenced. The migration ability of the resultant cells on the collagen gel has been monitored by complementary optical techniques: the conventional light microscopy; optical coherence tomography and Fourier Transform Infrared Microspcopic Spectroscopy (FTIR) using Synchrotron beam source. It is found that the cells expressing CCND1 exhibited cell invasion morphology and had different matrix compositions near the cell layer in comparison to the cells not expressing CCND1. The results from this study are consistent with published findings that expression of CCND1 has oncogenic potential and is involved in cell invasion in vitro. Application of complementary optical techniques proves to be an efficient way obtaining morphological and composition information of cell invasion.

  2. Optical interconnection for a polymeric PLC device using simple positional alignment.

    PubMed

    Ryu, Jin Hwa; Kim, Po Jin; Cho, Cheon Soo; Lee, El-Hang; Kim, Chang-Seok; Jeong, Myung Yung

    2011-04-25

    This study proposes a simple cost-effective method of optical interconnection between a planar lightwave circuit (PLC) device chip and an optical fiber. It was conducted to minimize and overcome the coupling loss caused by lateral offset which is due to the process tolerance and the dimensional limitation existing between PLC device chips and fiber array blocks with groove structures. A PLC device chip and a fiber array block were simultaneously fabricated in a series of polymer replication processes using the original master. The dimensions (i.e., width and thickness) of the under-clad of the PLC device chip were identical to those of the fiber array block. The PLC device chip and optical fiber were aligned by simple positional control for the vertical direction of the PLC device chip under a particular condition. The insertion loss of the proposed 1 x 2 multimode optical splitter device interconnection was 4.0 dB at 850 nm and the coupling loss was below 0.1 dB compared with single-fiber based active alignment.

  3. Using naturally occurring polysaccharides to align molecules with nonlinear optical activity

    NASA Technical Reports Server (NTRS)

    Prasthofer, Thomas

    1996-01-01

    The Biophysics and Advanced Materials Branch of the Microgravity Science and Applications Division at Marshall Space Flight Center has been investigating polymers with the potential for nonlinear optical (NLO) applications for a number of years. Some of the potential applications for NLO materials include optical communications, computing, and switching. To this point the branch's research has involved polydiacetylenes, phthalocyanins, and other synthetic polymers which have inherent NLO properties. The aim of the present research is to investigate the possibility of using naturally occurring polymers such as polysaccharides or proteins to trap and align small organic molecules with useful NLO properties. Ordering molecules with NLO properties enhances 3rd order nonlinear effects and is required for 2nd order nonlinear effects. Potential advantages of such a system are the flexibility to use different small molecules with varying chemical and optical properties, the stability and cost of the polymers, and the ability to form thin, optically transparent films. Since the quality of any polymer films depends on optimizing ordering and minimizing defects, this work is particularly well suited for microgravity experiments. Polysaccharide and protein polymers form microscopic crystallites which must align to form ordered arrays. The ordered association of crystallites is disrupted by gravity effects and NASA research on protein crystal growth has demonstrated that low gravity conditions can improve crystal quality.

  4. Polishing techniques for MEGARA pupil elements optics

    NASA Astrophysics Data System (ADS)

    Izazaga, R.; Carrasco, E.; Aguirre, D.; Salas, A.; Gil de Paz, A.; Gallego, J.; Iglesias, J.; Arroyo, J. M.; Hernández, M.; López, N.; López, V.; Quechol, J. T.; Salazar, M. F.; Carballo, C.; Cruz, E.; Arriaga, J.; De la Luz, J. A.; Huepa, A.; Jaimes, G. L.; Reyes, J.

    2016-07-01

    MEGARA (Multi-Espectrógrafo en GTC de Alta Resolución para Astronomía) is the new integral-field and multi-object optical spectrograph for the 10.4m Gran Telescopio Canarias.. It will offer RFWHM 6,000, 12,000 and 18,700 for the low- , mid- and high-resolution, respectively in the wavelength range 3650-9700Å. .The dispersive elements are volume phase holographic (VPH) gratings, sandwiched between two flat Fused Silica windows of high optical precision in large apertures. The design, based in VPHs in combination with Ohara PBM2Y prisms allows to keep the collimator and camera angle fixed. Seventy three optical elements are being built in Mexico at INAOE and CIO. For the low resolution modes, the VPHs windows specifications in irregularity is 1 fringe in 210mm x 170mm and 0.5 fringe in 190mm x 160mm. for a window thickness of 25 mm. For the medium and high resolution modes the irregularity specification is 2 fringes in 220mm x 180mm and 1 fringe in 205mm x 160mm, for a window thickness of 20mm. In this work we present a description of the polishing techniques developed at INAOE optical workshop to fabricate the 36 Fused Silica windows and 24 PBM2Y prisms that allows us to achieve such demanding specifications. We include the processes of mounting, cutting, blocking, polishing and testing.

  5. Alignment of 3-D optical coherence tomography scans to correct eye movement using a particle filtering.

    PubMed

    Xu, Juan; Ishikawa, Hiroshi; Wollstein, Gadi; Kagemann, Larry; Schuman, Joel S

    2012-07-01

    Eye movement artifacts occurring during 3-D optical coherence tomography (OCT) scanning is a well-recognized problem that may adversely affect image analysis and interpretation. A particle filtering algorithm is presented in this paper to correct motion in a 3-D dataset by considering eye movement as a target tracking problem in a dynamic system. The proposed particle filtering algorithm is an independent 3-D alignment approach, which does not rely on any reference image. 3-D OCT data is considered as a dynamic system, while the location of each A-scan is represented by the state space. A particle set is used to approximate the probability density of the state in the dynamic system. The state of the system is updated frame by frame to detect A-scan movement. The proposed method was applied on both simulated data for objective evaluation and experimental data for subjective evaluation. The sensitivity and specificity of the x-movement detection were 98.85% and 99.43%, respectively, in the simulated data. For the experimental data (74 3-D OCT images), all the images were improved after z-alignment, while 81.1% images were improved after x-alignment. The proposed algorithm is an efficient way to align 3-D OCT volume data and correct the eye movement without using references.

  6. Information hiding technique using optical correlators

    NASA Astrophysics Data System (ADS)

    Kim, Kyu-Tae; Kim, Jung-Jin; Kim, Eun-Soo

    2001-08-01

    During the past few years a variety of techniques have emerged to hide specific information within multimedia data for copyright protection, tamper-proofing and secret communication. The schemes for information hiding that have been proposed so far used either digital signal processing software or hardware. So they inevitably have a problem in some applications like automatic copyright control system, which need fast data-extracting scheme. In this paper, we show that the newly proposed optical correlator-based information hiding system has an advantage in that sense. In this scheme it is possible to simultaneously extract all the data hidden in one stego image and furthermore it is also possible to simultaneously extract all the data hidden in several stego images using optical correlators such as matched spatial filter and joint transform correlator.

  7. Optical techniques for measurement of high temperatures

    SciTech Connect

    Veligdan, J.T.

    1991-10-25

    The availability of instrumentation to measure the high outlet gas temperature of a particle bed reactor is a topic of some concern. There are a number of possible techniques with advantages and disadvantages. In order to provide some baseline choice of instrumentation, a review has been conducted of these various technologies. This report summarizes the results of this review for a group of technologies loosely defined as optical techniques (excluding optical pyrometry). The review has concentrated on a number of questions for each technology investigated. These are: (1) Description of the technology, (2) Anticipated sensitivity and accuracy, (3) Requirements for implementation, (4) Necessary development time and costs, (5) Advantages and disadvantages of the technology. Each of these areas was considered for a technology and a large number of technologies were considered in a review of the literature. Based upon this review it was found that a large number of methods exist to measure temperatures in excess of 2000 K. None of the methods found were ideal. Four methods, however, appeared to warrant further consideration: opto-mechanical expansion thermometry, surface Raman spectroscopy, gas-phase Raman spectroscopy and coherent anti-Stokes Raman spectroscopy (CARS). These techniques will be discussed further in this document.

  8. Computational chemistry modeling and design of photoswitchable alignment materials for optically addressable liquid crystal devices

    NASA Astrophysics Data System (ADS)

    Marshall, K. L.; Sekera, E. R.; Xiao, K.

    2015-09-01

    Photoalignment technology based on optically switchable "command surfaces" has been receiving increasing interest for liquid crystal optics and photonics device applications. Azobenzene compounds in the form of low-molar-mass, watersoluble salts deposited either directly on the substrate surface or after dispersion in a polymer binder have been almost exclusively employed for these applications, and ongoing research in the area follows a largely empirical materials design and development approach. Recent computational chemistry advances now afford unprecedented opportunities to develop predictive capabilities that will lead to new photoswitchable alignment layer materials with low switching energies, enhanced bistability, write/erase fatigue resistance, and high laser-damage thresholds. In the work described here, computational methods based on the density functional theory and time-dependent density functional theory were employed to study the impact of molecular structure on optical switching properties in photoswitchable methacrylate and acrylamide polymers functionalized with azobenzene and spiropyran pendants.

  9. The stonehenge technique: a new method of crystal alignment for coherent bremsstrahlung experiments

    NASA Astrophysics Data System (ADS)

    Livingston, Kenneth

    2005-08-01

    In the coherent bremsstrahlung technique a thin diamond crystal oriented correctly in an electron beam can produce photons with a high degree of linear polarization.1 The crystal is mounted on a goniometer to control its orientation and it is necessary to measure the angular offsets a) between the crystal axes and the goniometer axes and b) between the goniometer and the electron beam axis. A method for measuring these offsets and aligning the crystal was developed by Lohman et al, and has been used successfully in Mainz.2 However, recent attempts to investigate new crystals have shown that this approach has limitations which become more serious at higher beam energies where more accurate setting of the crystal angles, which scale with l/Ebeam, is required. (Eg. the recent installation of coherent bremsstrahlung facility at Jlab, with Ebeam = 6 GeV ) This paper describes a new, more general alignment technique, which overcomes these limitations. The technique is based on scans where the horizontal and vertical rotation axes of the goniometer are adjusted in a series of steps to make the normal to the crystal describe a cone of a given angle. For each step in the scan, the photon energy spectrum is measured using a tagging spectrometer, and the offsets between the electron beam and the crystal lattice are inferred from the resulting 2D plot. Using this method, it is possible to align the crystal with the beam quickly, and hence to set any desired orientation of the crystal relative to the beam. This is essential for any experiment requiring linearly polarized photons produced via coherent bremsstrahlung, and is also required for a systematic study of the channeling radiation produced by the electron beam incident on the crystal.

  10. Optical multichannel analyzer techniques for high resolution optical spectroscopy

    SciTech Connect

    Chao, J.L.

    1980-06-01

    The development of optical multichannel analyzer techniques for UV/VIS spectroscopy is presented. The research focuses on the development of spectroscopic techniques for measuring high resolution spectral lineshape functions from the exciton phosphorescence in H/sub 2/-1,2,4,5-tetrachlorobenzene. It is found that the temperature dependent frequency shifts and widths confirm a theoretical model based on an exchange theory. The exchange of low energy phonon modes which couple with excited state exciton transitions is shown to display the proper temperature dependent behavior. In addition to the techniques for using the optical multichannel analyzer (OMA) to perform low light level target integration, the use of the OMA for capturing spectral information in transient pulsed laser applications is discussed. An OMP data acquisition system developed for real-time signal processng is described. Both hardware and software interfacing considerations for control and data acquisition by a microcomputer are described. The OMA detector is described in terms of the principles behind its photoelectron detection capabilities and its design is compared with other optoelectronic devices.

  11. Alignment, rotation, and spinning of single plasmonic nanoparticles and nanowires using polarization dependent optical forces.

    PubMed

    Tong, Lianming; Miljković, Vladimir D; Käll, Mikael

    2010-01-01

    We demonstrate optical alignment and rotation of individual plasmonic nanostructures with lengths from tens of nanometers to several micrometers using a single beam of linearly polarized near-infrared laser light. Silver nanorods and dimers of gold nanoparticles align parallel to the laser polarization because of the high long-axis dipole polarizability. Silver nanowires, in contrast, spontaneously turn perpendicular to the incident polarization and predominantly attach at the wire ends, in agreement with electrodynamics simulations. Wires, rods, and dimers all rotate if the incident polarization is turned. In the case of nanowires, we demonstrate spinning at an angular frequency of approximately 1 Hz due to transfer of spin angular momentum from circularly polarized light.

  12. Fabrication of Vertically Aligned Carbon Nanotube or Zinc Oxide Nanorod Arrays for Optical Diffraction Gratings.

    PubMed

    Kim, Jeong; Kim, Sun Il; Cho, Seong-Ho; Hwang, Sungwoo; Lee, Young Hee; Hur, Jaehyun

    2015-11-01

    We report on new fabrication methods for a transparent, hierarchical, and patterned electrode comprised of either carbon nanotubes or zinc oxide nanorods. Vertically aligned carbon nanotubes or zinc oxide nanorod arrays were fabricated by either chemical vapor deposition or hydrothermal growth, in combination with photolithography. A transparent conductive graphene layer or zinc oxide seed layer was employed as the transparent electrode. On the patterned surface defined using photoresist, the vertically grown carbon nanotubes or zinc oxides could produce a concentrated electric field under applied DC voltage. This periodic electric field was used to align liquid crystal molecules in localized areas within the optical cell, effectively modulating the refractive index. Depending on the material and morphology of these patterned electrodes, the diffraction efficiency presented different behavior. From this study, we established the relationship between the hierarchical structure of the different electrodes and their efficiency for modulating the refractive index. We believe that this study will pave a new path for future optoelectronic applications.

  13. Optical test bench for high precision metrology and alignment of zoom sub-assembly components

    NASA Astrophysics Data System (ADS)

    Leprêtre, F.; Levillain, E.; Wattellier, B.; Delage, P.; Brahmi, D.; Gascon, A.

    2013-09-01

    Thales Angénieux (TAGX) designs and manufactures zoom lens assemblies for cinema applications. These objectives are made of mobile lens assemblies. These need to be precisely characterized to detect alignment, polishing or glass index homogeneity errors, which amplitude may range to a few hundreds of nanometers. However these assemblies are highly aberrated with mainly spherical aberration (>30 μm PV). PHASICS and TAGX developed a solution based on the use of a PHASICS SID4HR wave front sensor. This is based on quadri-wave lateral shearing interferometry, a technology known for its high dynamic range. A 100-mm diameter He:Ne source illuminates the lens assembly entrance pupil. The transmitted wave front is then directly measured by the SID4- HR. The measured wave front (WFmeas) is then compared to a simulation from the lens sub-assembly optical design (WFdesign). We obtain a residual wave front error (WFmanufactured), which reveals lens imperfections due to its manufacturing. WFmeas=WFdesign+(WFEradius+WFEglass+WFEpolish)=WF design + WFmanufactured The optical test bench was designed so that this residual wave front is measured with a precision below 100 nm PV. The measurement of fast F-Number lenses (F/2) with aberrations up to 30 μm, with a precision of 100 nm PV was demonstrated. This bench detects mismatches in sub-assemblies before the final integration step in the zoom. Pre-alignment is also performed in order to overpass the mechanical tolerances. This facilitates the completed zoom alignment. In final, productivity gains are expected due to alignment and mounting time savings.

  14. Optical Dichroism in Fibers of Aligned SWNT Inferred from Polarized Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Alldredge, J. W.; Gommans, H. H.; Tashiro, H.; Park, J.; Magnuson, J.; Rinzler, A. G.

    2000-03-01

    To probe the 1D nature of single wall carbon nanotubes (SWNT) in bulk samples we devised a method for generating fibers of aligned SWNT. We measured polarization dependent Raman spectra on the oriented fibers to verify mode assignments appearing in the literature. Surprisingly, ALL the Raman line intensities are observed to decrease in EQUAL amounts for 647.1 nm laser excitation polarized perpendicular to the fiber axis versus that polarized parallel to the fiber axis. We attribute this anisotropy to a consequence of the 1D nature of the nanotubes. The strong Raman signal from SWNT has been ascribed to resonance Raman scattering with optical transitions between van Hove singularities in the 1D density of states. When the excitation is polarized along the nanotube axis it excites transitions between these singularities in the (metallic) nanotubes of the sample. For the polarization perpendicular to the nanotube axis, evidently no such optical transitions (resonant with our laser) are available, yielding the uniformly smaller Raman signal. The fibers thus exhibit optical dichroism. This effect frustrates the use of polarized Raman spectroscopy for identification of vibration mode symmetries, however the Raman polarization ratio provides a convenient measure of the degree of SWNT alignment in the fibers .

  15. Space optical navigation techniques: an overview

    NASA Astrophysics Data System (ADS)

    Rebordão, J. M.

    2013-11-01

    Optical or vision-based navigation is an enabling technology for satellite autonomous navigation associated to different navigation approaches such as cruising, fly-by, terrain relative navigation, landing, rendezvous and docking between spacecrafts, rigidity of multi-satellite constellations. Since 2001, in many different ESA projects, the author and his team (at INETI and currently at FCUL) have been associated to most of the developments of the optical components of autonomous navigation, in cooperation with space primes or GNC subsystems suppliers. A unique experience related to seemingly simple photonic concepts associated to computational vision, photonic noises, camera tradeoffs and system concepts has emerged, and deserves a synthesis especially because some of these concepts are being implemented in the ESA Proba 3 mission and ESA is currently updating the technology in view of forthcoming planetary missions to Jupiter, Jupiter moons and asteroids. It is important to note that the US have already flown several missions relying on autonomous navigation and that NASA experience is at least one decade old. System approaches, sources of difficulty, some tradeoffs in both (and between) hardware and software, critical interface issues between the imaging and GNC (Guidance, Navigation and Control) subsystems, image processing techniques, utilization of apriori or to be estimated information, uncertainties, simulation of the imaging chain and non-cooperative environments will be addressed synthetically for both passive (optical) and active (lidar) systems.

  16. Assembly, Alignment, And Cold Focus Test Methods Utilized On Claes Optics

    NASA Astrophysics Data System (ADS)

    Dawson, Juan C.; Kauer, John F.; Reilly, Charles M.; Steakley, Bruce C.

    1988-04-01

    The CLAES Telescope and Spectrometer were aligned as separate units. The optical interface between the two units is at the intermediate Lyot stop, where close angular and centering tolerances are required, with control by the use of matched machined tooling. In the alignme-L. of the Spectrometer, all optical components were centered to the chief ray using centering targets to align the optical components. The initial assembly was made at room temperature, and tested at 20K. One key reason for this testing is that the refractive indices for ZnS and ZnSe are not known below 90K, and therefore the exact location of the image plane is not known. The tests at 20K established the location of the image plane. A beam of collimated carbon-dioxide laser power illuminates the cryogenically cooled Spectrometer or the CLAES Instrument along the optical axis. The collimation of the beam is adjustable in small increments; the beam is scanned over the edges of the individual detectors creating edge scans that were used to determine where the image plane is located. Given the offset from exact collimation of the input beam, the corrections required to locate the image at the detector plane are computed. To determine "best focus", the inverse of the slopes of the edge-traces are plotted. Data obtained on both sides of best focus is plotted; the curves look like parabolas with upward arms. The minimum of this curve is defined as the location of the image plane. Shims that compensate for the focus errors are cut to the correct thickness, and installed. In addition to setting focus, the cryogenic tests were used to determine stability of the optics over the specified environment, and blur size measurements were performed at operational temperatures.

  17. Passive optically encoded transponder (POET) - An acquisition and alignment target for autonomous robotics

    NASA Astrophysics Data System (ADS)

    White, G. K.

    1987-01-01

    This paper shows that it is possible to produce a three-dimensional target from a two-dimensional transponder that can enhance the capabilities of an optical measurement or alignment system, and that the autonomous operation of such a system is possible. The attitude and position resolution that is possible using such a configuration would allow noncontact coordinate system transfer and tracking capability in a robotic system, enabling a robot to access the physical database of an acquired, known target item and inspect, attach to, or manipulate any external part of the item in a teleoperated or autonomous mode without sophisticated visual capabilities.

  18. TiO₂ nanowire dispersions in viscous polymer matrix: electrophoretic alignment and optical properties.

    PubMed

    Šutka, Andris; Saal, Kristjan; Kisand, Vambola; Lõhmus, Rünno; Joost, Urmas; Timusk, Martin

    2014-10-17

    The changes in optical properties during TiO₂ nanowire orientation in polydimethylsiloxane (PDMS) matrix under the influence of an electric field are strongly influenced by nanowire (NW) diameter. It was demonstrated for the first time that either positive or negative change in transmittance can be induced by NW alignment parallel to the electric field depending on the NW diameter. These effects can be explained by the interplay between scattering and reflectance. Experimental findings reported could be important for smart window applications for the regulation of visible or even infrared transparency, thus reducing the energy consumption by air conditioning systems in buildings and automobiles in the future.

  19. A two-in-one Faraday rotator mirror exempt of active optical alignment.

    PubMed

    Wan, Qiong; Wan, Zhujun; Liu, Hai; Liu, Deming

    2014-02-10

    A two-in-one Faraday rotator mirror was presented, which functions as two independent Faraday rotation mirrors with a single device. With the introduction of a reflection lens as substitution of the mirror in traditional structure, this device is characterized by exemption of active optical alignment for the designers and manufacturers of Faraday rotator mirrors. A sample was fabricated by passive mechanical assembly. The insertion loss was measured as 0.46 dB/0.50 dB for the two independent ports, respectively.

  20. Rethinking Program Assessment through the Use of Program Alignment Mapping Technique

    ERIC Educational Resources Information Center

    Liu, Min; Wrobbel, Duff; Blankson, Isaac

    2010-01-01

    Curriculum mapping is a well-known assessment tool used to articulate and align a curriculum. The authors present an improved method of curriculum alignment that combines the traditional curriculum mapping with what is often called prerequisite mapping. This improved method of curriculum alignment mapping we label Program Alignment Mapping (PAM)…

  1. Optical stimulation of the prostate nerves: A potential diagnostic technique

    NASA Astrophysics Data System (ADS)

    Tozburun, Serhat

    There is wide variability in sexual potency rates (9--86%) after nerve-sparing prostate cancer surgery due to limited knowledge of the location of the cavernous nerves (CN's) on the prostate surface, which are responsible for erectile function. Thus, preservation of the CN's is critical in preserving a man's ability to have spontaneous erections following surgery. Nerve-mapping devices, utilizing conventional Electrical Nerve Stimulation (ENS) techniques, have been used as intra-operative diagnostic tools to assist in preservation of the CN. However, these technologies have proven inconsistent and unreliable in identifying the CN's due to the need for physical contact, the lack of spatial selectivity, and the presence of electrical artifacts in measurements. Optical Nerve Stimulation (ONS), using pulsed infrared laser radiation, is studied as an alternative to ENS. The objective of this study is sevenfold: (1) to develop a laparoscopic laser probe for ONS of the CN's in a rat model, in vivo; (2) to demonstrate faster ONS using continuous-wave infrared laser radiation; (3) to describe and characterize the mechanism of successful ONS using alternative laser wavelengths; (4) to test a compact, inexpensive all-single-mode fiber configuration for optical stimulation of the rat CN studies; (5) to implement fiber optic beam shaping methods for comparison of Gaussian and flat-top spatial beam profiles during ONS; (6) to demonstrate successful ONS of CN's through a thin layer of fascia placed over the nerve and prostate gland; and (7) to verify the experimentally determined therapeutic window for safe and reliable ONS without thermal damage to the CN's by comparison with a computational model for thermal damage. A 5.5-Watt Thulium fiber laser operated at 1870 nm and two pigtailed, single mode, near-IR diode lasers (150-mW, 1455-nm laser and 500-mW, 1550-nm laser) were used for non-contact stimulation of the rat CN's. Successful laser stimulation, as measured by an

  2. Alignment issues, correlation techniques and their assessment for a visible light imaging-based 3D printer quality control system

    NASA Astrophysics Data System (ADS)

    Straub, Jeremy

    2016-05-01

    Quality control is critical to manufacturing. Frequently, techniques are used to define object conformity bounds, based on historical quality data. This paper considers techniques for bespoke and small batch jobs that are not statistical model based. These techniques also serve jobs where 100% validation is needed due to the mission or safety critical nature of particular parts. One issue with this type of system is alignment discrepancies between the generated model and the physical part. This paper discusses and evaluates techniques for characterizing and correcting alignment issues between the projected and perceived data sets to prevent errors attributable to misalignment.

  3. Optimal Parameter Design of Coarse Alignment for Fiber Optic Gyro Inertial Navigation System.

    PubMed

    Lu, Baofeng; Wang, Qiuying; Yu, Chunmei; Gao, Wei

    2015-06-25

    Two different coarse alignment algorithms for Fiber Optic Gyro (FOG) Inertial Navigation System (INS) based on inertial reference frame are discussed in this paper. Both of them are based on gravity vector integration, therefore, the performance of these algorithms is determined by integration time. In previous works, integration time is selected by experience. In order to give a criterion for the selection process, and make the selection of the integration time more accurate, optimal parameter design of these algorithms for FOG INS is performed in this paper. The design process is accomplished based on the analysis of the error characteristics of these two coarse alignment algorithms. Moreover, this analysis and optimal parameter design allow us to make an adequate selection of the most accurate algorithm for FOG INS according to the actual operational conditions. The analysis and simulation results show that the parameter provided by this work is the optimal value, and indicate that in different operational conditions, the coarse alignment algorithms adopted for FOG INS are different in order to achieve better performance. Lastly, the experiment results validate the effectiveness of the proposed algorithm.

  4. Automated alignment system for optical wireless communication systems using image recognition.

    PubMed

    Brandl, Paul; Weiss, Alexander; Zimmermann, Horst

    2014-07-01

    In this Letter, we describe the realization of a tracked line-of-sight optical wireless communication system for indoor data distribution. We built a laser-based transmitter with adaptive focus and ray steering by a microelectromechanical systems mirror. To execute the alignment procedure, we used a CMOS image sensor at the transmitter side and developed an algorithm for image recognition to localize the receiver's position. The receiver is based on a self-developed optoelectronic integrated chip with low requirements on the receiver optics to make the system economically attractive. With this system, we were able to set up the communication link automatically without any back channel and to perform error-free (bit error rate <10⁻⁹) data transmission over a distance of 3.5 m with a data rate of 3 Gbit/s.

  5. Simple integration technique to realize parallel optical interconnects: implementation of a pluggable two-dimensional optical data link

    NASA Astrophysics Data System (ADS)

    Goulet, Alain; Naruse, Makoto; Ishikawa, Masatoshi

    2002-09-01

    An assembly technique is presented to realize pluggable or fully integrated optoelectronic systems based on image relays. A method to visually align and assemble optoelectronic chips or fiber bundles to half of a relay is explained. To validate this technique, two-dimensional arrays of vertical-cavity surface-emitting lasers and photodetectors and a fiber image guide have been integrated to gradient index lenses with simple optomechanical parts. Although the connection of these modules was realized with +/-0.5 mm lateral tolerances, parallel optical interconnects were successfully achieved at 10 MHz. The lateral misalignment between chips was on average 20 μm and at worst 60 μm.

  6. Neural-network-directed alignment of optical systems using the laser-beam spatial filter as an example

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.; Krasowski, Michael J.; Weiland, Kenneth E.

    1993-01-01

    This report describes an effort at NASA Lewis Research Center to use artificial neural networks to automate the alignment and control of optical measurement systems. Specifically, it addresses the use of commercially available neural network software and hardware to direct alignments of the common laser-beam-smoothing spatial filter. The report presents a general approach for designing alignment records and combining these into training sets to teach optical alignment functions to neural networks and discusses the use of these training sets to train several types of neural networks. Neural network configurations used include the adaptive resonance network, the back-propagation-trained network, and the counter-propagation network. This work shows that neural networks can be used to produce robust sequencers. These sequencers can learn by example to execute the step-by-step procedures of optical alignment and also can learn adaptively to correct for environmentally induced misalignment. The long-range objective is to use neural networks to automate the alignment and operation of optical measurement systems in remote, harsh, or dangerous aerospace environments. This work also shows that when neural networks are trained by a human operator, training sets should be recorded, training should be executed, and testing should be done in a manner that does not depend on intellectual judgments of the human operator.

  7. Data veracity checks for the alignment of the JWST optical telescope element

    NASA Astrophysics Data System (ADS)

    Levi, Josh; Glassman, Tiffany; Farey, Mike; Liepmann, Till

    2016-09-01

    Alignment of the James Webb Space Telescope (JWST) Optical Telescope Element (OTE) requires a multitude of demanding and exacting dimensional and positional measurements. Many of the alignment requirements are in the range of hundreds of microns over significant distances (up to 8 m) on a flexible structure, which creates stringent accuracy demands on the alignment measurements. Furthermore, to optimize the performance of the system, the telescope is aligned to a relatively small (<1 m) structure in the center, creating the potential for coordinate system errors. Measurements have been performed using laser trackers (predominantly), photogrammetry, coordinate measurement machine (CMM), and laser radar instruments. Measurements from different instruments/ stations are combined and processed within SpatialAnalyzer (SA) commercial software using the Unified Spatial Metrology Network (USMN) feature. While this approach should yield the best possible accuracies (hopefully in the tens of microns range), our experience has been that there can be significant errors in the data based on the details of how SA is set up and how the measurements are conducted. As a result of our experience, we have developed analytical tools and processes that allow us to test the data veracity in near real time using, for example, Excel spreadsheet calculations. These tools combine measurements made at various levels of assembly, measurements of cross check points, and finite element analysis to determine the correlated and uncorrelated discrepancies in the measured data. This provides a detailed understanding of systematic and random measurement errors and has allowed us to quickly uncover issues with placement, measurement, and modeling, as well as to quantify our measurement performance.

  8. Wave-optical assessment of alignment tolerances in nano-focusing with ellipsoidal mirror

    SciTech Connect

    Yumoto, Hirokatsu Koyama, Takahisa; Ohashi, Haruhiko

    2016-01-28

    High-precision ellipsoidal mirrors, which can efficiently focus X-rays to the nanometer dimension with a mirror, have not been realized because of the difficulties in the fabrication process. The purpose of our study was to develop nano-focusing ellipsoidal mirrors in the hard X-ray region. We developed a wave-optical focusing simulator for investigating alignment tolerances in nano-focusing with a designed ellipsoidal mirror, which produce a diffraction-limited focus size of 30 × 35 nm{sup 2} in full width at half maximum at an X-ray energy of 7 keV. The simulator can calculate focusing intensity distributions around the focal point under conditions of misalignment. The wave-optical simulator enabled the calculation of interference intensity distributions, which cannot be predicted by the conventional ray-trace method. The alignment conditions with a focal length error of ≲ ±10 µm, incident angle error of ≲ ±0.5 µrad, and in-plane rotation angle error of ≲ ±0.25 µrad must be satisfied for nano-focusing.

  9. Wave-optical assessment of alignment tolerances in nano-focusing with ellipsoidal mirror

    NASA Astrophysics Data System (ADS)

    Yumoto, Hirokatsu; Koyama, Takahisa; Matsuyama, Satoshi; Yamauchi, Kazuto; Ohashi, Haruhiko

    2016-01-01

    High-precision ellipsoidal mirrors, which can efficiently focus X-rays to the nanometer dimension with a mirror, have not been realized because of the difficulties in the fabrication process. The purpose of our study was to develop nano-focusing ellipsoidal mirrors in the hard X-ray region. We developed a wave-optical focusing simulator for investigating alignment tolerances in nano-focusing with a designed ellipsoidal mirror, which produce a diffraction-limited focus size of 30 × 35 nm2 in full width at half maximum at an X-ray energy of 7 keV. The simulator can calculate focusing intensity distributions around the focal point under conditions of misalignment. The wave-optical simulator enabled the calculation of interference intensity distributions, which cannot be predicted by the conventional ray-trace method. The alignment conditions with a focal length error of ≲ ±10 µm, incident angle error of ≲ ±0.5 µrad, and in-plane rotation angle error of ≲ ±0.25 µrad must be satisfied for nano-focusing.

  10. Passive Optically Encoded Transponder (POET) An Acquisition And Alignment Target For Autonomous Robotics

    NASA Astrophysics Data System (ADS)

    White, G. K.

    1987-02-01

    Relative position information concerning an object that is to be acquired, attached to, or manipulated in some way by a robotic system is usually supplied by a known database or through vision information of some kind. Vision systems normally require some degree of intelligence to produce complete position information and therefore are relatively sophisticated, slow, or both. Simple "targets" require some amount of pattern recognition in autonomous operations and do not usually lend themselves to precision applications. This paper describes work on a discrete optical element prototype target which when interrogated by a video camera system, will provide noncontact relative position information about all 6 degrees-of-freedom (DOF). This information is available within the active field of view (FOV) of the transponder and could be processed by microprocessor-based, software algorithms with simple pattern recognition capabilities. The interrogation system (camera) is composed of a standard charge injection device (CID) array video camera, a controllable macrozoom lens, a liquid crystal shutter (LCS), and a point-source multispectral illuminator. This allows the transponder to be used where a standard video camera vision system is needed, or already implemented, and results in a relatively fast system (approximately 10 Hz). A passive optically encoded transponder (POET) implemented in a "stick-on" holographic optical element (HOE) is proposed as a next generation target, to supply relative position information in all 6 DOF for acquisition and precision alignment. In applications requiring maximum bandwidth and resolution, the fact that no "pattern recognition" is required in the proposed system results in the ability to interrogate the transponder in real time with a dedicated nonvision, interrogation system, resulting in a multiorder of magnitude increase in speed. The transponder (target) is configured to provide optimum information for the intended use. Being

  11. New metrology techniques improve the production of silicon diffractive optics

    NASA Astrophysics Data System (ADS)

    Brooks, Cynthia B.; Gully-Santiago, Michael; Grigas, Michelle; Jaffe, Daniel T.

    2014-07-01

    Silicon immersion gratings and grisms offer significant advantages in compactness and performance over frontsurface gratings and over grisms made from lower-index materials. At the same time, the high refractive index of Si (3.4) leads to very stringent constraints on the allowable groove position errors, typically rms < 20 nm over 100 mm and repetitive error of <5 nm amplitude. For both types of devices, we produce grooves in silicon using photolithography, plasma etching, and wet etching. To date, producers have used contact photolithography to pattern UV sensitive photoresist as the initial processing step, then transferred this pattern to a layer of silicon nitride that, in turn, serves as a hard mask during the wet etching of grooves into silicon. For each step of the groove production, we have used new and sensitive techniques to determine the contribution of that step to the phase non-uniformity. Armed with an understanding of the errors and their origins, we could then implement process controls for each step. The plasma uniformity was improved for the silicon nitride mask etch process and the phase contribution of the plasma etch step was measured. We then used grayscale lithography, a technique in which the photoresist is deliberately underexposed, to measure large-scale nonuniformities in the UV exposure system to an accuracy of 3-5%, allowing us to make corrections to the optical alignment. Additionally, we used a new multiple-exposure technique combined with laser interferometry to measure the relationship between UV exposure dose and line edge shift. From these data we predict the contribution of the etching and photolithographic steps to phase error of the grating surface. These measurements indicate that the errors introduced during the exposure step dominate the contributions of all the other processing steps. This paper presents the techniques used to quantify individual process contributions to phase errors and steps that were taken to improve

  12. Preparation of aligned porous chitin nanowhisker foams by directional freeze-casting technique.

    PubMed

    Zhou, Yiming; Fu, Shiyu; Pu, Yunqiao; Pan, Shaobo; Ragauskas, Arthur J

    2014-11-04

    Structured biofoams with aligned porous structures were fabricated from nanosized chitin by employing a directional freeze-casting technique. The effects of the freezing conditions and slurry formulation on nanochitin foam morphology were investigated. The morphology of obtained foams was characterized using scanning electron microscopy (SEM). It was found that the pore structure of the obtained foams was a likewise of the ice crystals formed during the directional freezing. The results indicate that directional freeze-casting protocol can significantly influence the morphological features and microstructures of the obtained biofoams which could have numerous applications, including engineered carriers, scaffolds, filters and specifically as a template for potential multi-layered composites after infusion with a second phase.

  13. Optimal sun-alignment techniques of large solar arrays in electric propulsion spacecraft

    NASA Technical Reports Server (NTRS)

    Meissinger, H. F.; Dailey, C. L.; Valgora, M. E.

    1982-01-01

    Optimum sun-alignment of large solar arrays in electric propulsion spacecraft operating in earth orbit requires periodic roll motions around the thrust axis, synchronized with the apparent conical motion of the sun line. This oscillation is sustained effectively with the aid of gravity gradient torques while only a small share of the total torque is being contributed by the attitude control system. Tuning the system for resonance requires an appropriate choice of moment-of-inertia characteristics. To minimize atmospheric drag at low orbital altitudes the solar array is oriented parallel, or nearly parallel, to the flight direction. This can increase the thrust-to-drag ratio by as much as an order of magnitude. Coupled with optimal roll orientation, this feathering technique will permit use of electric propulsion effectively at low altitudes in support of space shuttle or space station activities and in spiral ascent missions.

  14. Spectroelectrochemistry: The Combination of Optical and Electrochemical Techniques.

    ERIC Educational Resources Information Center

    Heineman, William R.

    1983-01-01

    Two different techniques, electrochemistry and spectroscopy, can be combined for studying the redox chemistry of inorganic, organic, and biological molecules. Several commonly used spectroelectrochemical methods and their applications are described. Includes discussions of optically transparent electrodes, optical absorption/fluorescence…

  15. Optics of Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII): delay lines and alignment

    NASA Astrophysics Data System (ADS)

    Dhabal, Arnab; Rinehart, Stephen A.; Rizzo, Maxime J.; Mundy, Lee

    2016-07-01

    We present the optics of Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) as it gets ready for launch. BETTII is an 8-meter baseline far-infrared (30-90 μm) interferometer mission with capabilities of spatially resolved spectroscopy aimed at studying star formation and galaxy evolution. The instrument collects light from its two arms, makes them interfere, divides them into two science channels (30-50 μm and 60-90 μm), and focuses them onto the detectors. It also separates out the NIR light (1-2.5 μm) and uses it for tip-tilt corrections of the telescope pointing. Currently, all the optical elements have been fabricated, heat treated, coated appropriately and are mounted on their respective assemblies. We are presenting the optical design challenges for such a balloon borne spatio- spectral interferometer, and discuss how they have been mitigated. The warm and cold delay lines are an important part of this optics train. The warm delay line corrects for path length differences between the left and the right arm due to balloon pendulation, while the cold delay line is aimed at introducing a systematic path length difference, thereby generating our interferograms from where we can derive information about the spectra. The details of their design and the results of the testing of these opto-mechanical parts are also discussed. The sensitivities of different optical elements on the interferograms produced have been determined with the help of simulations using FRED software package. Accordingly, an alignment plan is drawn up which makes use of a laser tracker, a CMM, theodolites and a LUPI interferometer.

  16. Modulated-alignment dual-axis (MAD) confocal microscopy for deep optical sectioning in tissues

    PubMed Central

    Leigh, Steven Y.; Chen, Ye; Liu, Jonathan T.C.

    2014-01-01

    A strategy is presented to enable optical-sectioning microscopy with improved contrast and imaging depth using low-power (0.5 - 1 mW) diode laser illumination. This technology combines the inherent strengths of focal-modulation microscopy and dual-axis confocal (DAC) microscopy for rejecting out-of-focus and multiply scattered background light in tissues. The DAC architecture is unique in that it utilizes an intersecting pair of illumination and collection beams to improve the spatial-filtering and optical-sectioning performance of confocal microscopy while focal modulation selectively ‘labels’ in-focus signals via amplitude modulation. Simulations indicate that modulating the spatial alignment of dual-axis beams at a frequency f generates signals from the focal volume of the microscope that are modulated at 2f with minimal modulation of background signals, thus providing nearly an order-of-magnitude improvement in optical-sectioning contrast compared to DAC microscopy alone. Experiments show that 2f lock-in detection enhances contrast and imaging depth within scattering phantoms and fresh tissues. PMID:24940534

  17. Note: Non-invasive optical method for rapid determination of alignment degree of oriented nanofibrous layers

    SciTech Connect

    Pokorny, M.; Rebicek, J.; Klemes, J.; Kotzianova, A.; Velebny, V.

    2015-10-15

    This paper presents a rapid non-destructive method that provides information on the anisotropic internal structure of nanofibrous layers. A laser beam of a wavelength of 632.8 nm is directed at and passes through a nanofibrous layer prepared by electrostatic spinning. Information about the structural arrangement of nanofibers in the layer is directly visible in the form of a diffraction image formed on a projection screen or obtained from measured intensities of the laser beam passing through the sample which are determined by the dependency of the angle of the main direction of polarization of the laser beam on the axis of alignment of nanofibers in the sample. Both optical methods were verified on Polyvinyl alcohol (PVA) nanofibrous layers (fiber diameter of 470 nm) with random, single-axis aligned and crossed structures. The obtained results match the results of commonly used methods which apply the analysis of electron microscope images. The presented simple method not only allows samples to be analysed much more rapidly and without damaging them but it also makes possible the analysis of much larger areas, up to several square millimetres, at the same time.

  18. Optical techniques for determining dynamic material properties

    SciTech Connect

    Paisley, D.L.; Stahl, D.B.

    1996-12-31

    Miniature plates are laser-launched with a 10-Joule Nd:YAG for one-dimensional (1-D) impacts on to target materials much like gas gun experiments and explosive plane wave plate launch. By making the experiments small, flyer plates (3 mm diameter x 50 micron thick) and targets (10 mm diameter x 200 micron thick), 1-D impact experiments can be performed in a standard laser-optical laboratory with minimum confinement and collateral damage. The laser-launched plates do not require the traditional sabot on gas guns nor the explosives needed for explosive planewave lenses, and as a result are much more amenable to a wide variety of materials and applications. Because of the small size very high pressure gradients can be generated with relative ease. The high pressure gradients result in very high strains and strain rates that are not easily generated by other experimental methods. The small size and short shock duration (1 - 20 ns) are ideal for dynamically measuring bond strengths of micron-thick coatings. Experimental techniques, equipment, and dynamic material results are reported.

  19. Surface diffusion studies by optical diffraction techniques

    SciTech Connect

    Xiao, X.D.

    1992-11-01

    The newly developed optical techniques have been combined with either second harmonic (SH) diffraction or linear diffraction off a monolayer adsorbate grating for surface diffusion measurement. Anisotropy of surface diffusion of CO on Ni(l10) was used as a demonstration for the second harmonic dim reaction method. The linear diffraction method, which possesses a much higher sensitivity than the SH diffraction method, was employed to study the effect of adsorbate-adsorbate interaction on CO diffusion on Ni(l10) surface. Results showed that only the short range direct CO-CO orbital overlapping interaction influences CO diffusion but not the long range dipole-dipole and CO-NI-CO interactions. Effects of impurities and defects on surface diffusion were further explored by using linear diffraction method on CO/Ni(110) system. It was found that a few percent S impurity can alter the CO diffusion barrier height to a much higher value through changing the Ni(110) surface. The point defects of Ni(l10) surface seem to speed up CO diffusion significantly. A mechanism with long jumps over multiple lattice distance initiated by CO filled vacancy is proposed to explain the observed defect effect.

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

    SciTech Connect

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

    2005-10-27

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

  1. Image Quality of the Evryscope: Method for On-Site Optical Alignment

    NASA Astrophysics Data System (ADS)

    Wulfken, Philip J.; Law, Nicholas M.; Ratzloff, Jeffrey; Fors, Octavi

    2015-01-01

    Previous wide field surveys have been conducted by taking many images each night to cover thousands of square degrees. The Evryscope is a new type of system designed to search for transiting exoplanets around nearby bright stars, M-dwarfs, white dwarfs, and other transients. The Evryscope is an array of 70 mm telescopes that will continuously image 10200 square degrees of the night sky at once. One of the image quality requirements is for the PSFs to be well-sampled at two pixels across and it was found that tilt caused by slight misalignment between the optics and the CCD increased the size of the FWHM towards the edges and corners of the image. Here we describe the image quality of the Evryscope cameras and the alignment procedure to achieve the required 2 pixel FWHM.

  2. Design and prototyping of self-centering optical single-mode fiber alignment structures

    NASA Astrophysics Data System (ADS)

    Ebraert, Evert; Gao, Fei; Beri, Stefano; Watté, Jan; Thienpont, Hugo; Van Erps, Jürgen

    2016-06-01

    The European Commission’s goal of providing each European household with at least a 30 Mb s-1 Internet connection by 2020 would be facilitated by a widespread deployment of fibre-to-the-home, which would in turn be sped up by the development of connector essential components, such as high-precision alignment features. Currently, the performance of state-of-the-art physical contact optical fiber connectors is limited by the tolerance on the cladding of standard telecom-grade single-mode fiber (SMF), which is typically smaller than  ±1 μm. We propose to overcome this limit by developing micro-spring-based self-centering alignment structures (SCAS) for SMF-connectors. We design these alignment structures with robustness and low-cost replication in mind, allowing for large-scale deployment. Both theoretical and finite element analysis (FEA) models are used to determine the optimal dimensions of the beams of which the micro-springs of the SCAS are comprised. Two topologies of the SCAS, consisting of three and four micro-springs respectively, are investigated for two materials: polysulfone (PSU) and polyetherimide (PEI). These materials hold great potential for high-performance fiber connectors while being compatible with low-cost production and with the harsh environmental operation conditions of those connectors. The theory and FEA agree well (<3% difference) for a simple micro-spring. When including a pedestal on the micro-spring (to bring it further away from the fiber) and for shorter spring lengths the agreement worsens. This is due to spring compression effects not being taken into account in our theoretical model. Prototypes are successfully fabricated using deep proton writing and subsequently characterized. The controlled insertion of an SMF in the SCAS is investigated and we determine that a force of 0.11 N is required. The fiber insertion also causes an out-of-plane deformation of the micro-springs in the SCAS of about 7 μm, which is no problem for

  3. Optical Modeling Activities for NASA's James Webb Space Telescope (JWST). 3; Wavefront Aberrations due to Alignment and Figure Compensation

    NASA Technical Reports Server (NTRS)

    Howard, Joseph

    2007-01-01

    This is part three of a series describing the ongoing optical modeling activities for James Webb Space Telescope (JWST). The first two discussed modeling JWST on-orbit performance using wavefront sensitivities to predict line of sight motion induced blur, and stability during thermal transients. The work here investigates the aberrations resulting from alignment and figure compensation of the controllable degrees of freedom (primary and secondary mirrors), which may be encountered during ground alignment and on-orbit commissioning of the observatory. The optical design of the telescope is a three-mirror anastigmat, with an active fold mirror at the exit pupil for fine guiding. The primary mirror is over 6.5 meters in diameter, and is composed of 18 hexagonal segments that can individually positioned on hexapods, as well as compensated for radius of curvature. This effectively gives both alignment and figure control of the primary mirror. The secondary mirror can be moved in rigid body only, giving alignment control of the telescope. The tertiary mirror is fixed, however, as well as the location of the science instrumentation. Simulations are performed of various combinations of active alignment corrections of component figure errors, and of primary mirror figure corrections of alignment errors. Single field point and moderate field knowledge is assumed in the corrections. Aberrations over the field are reported for the varying cases, and examples presented.

  4. Characterisation of Shape Accuracy During Alignment and Integration of Thin Shell Mirrors for Large Modular X-Ray Optics

    NASA Astrophysics Data System (ADS)

    Breunig, Elias; Friedrich, Peter; Proserpio, Laura; Winter, Anita; Baier, Horst

    2014-06-01

    MPE is developing modular x-ray mirrors for the next generation of high-energy astronomy missions. The mirror segments are based on thermally formed (a.k.a. slumped) glass sheets, with a typical thickness of 400μm.One of the major challenges is the alignment and integration of the mirror segments and the associated metrology. The optical performance of the mirror can be significantly compromised by adhesive shrinkage, gravity sag or residual stresses influenced by the properties of the mirror mounting and the integration procedure.In parallel with classic coordinate measurement techniques we utilize a deflectometry based metrology system to characterization shape errors of the mirror surfaces.A typical deflectometry setup uses a TFT display to project a sinusoidal pattern onto a specular test surface (SUT) and a camera that observes the reflected image. This reflected image contains slope information of the SUT in the form of distortions of the original displayed pattern. A phase shifting technique can be used to recover this slope information with only very few exposures and reasonable computational effort. The deflectometry system enables us to characterize bonding interfaces of slumped glass mirrors, as well as influence of temporary mounting points, handling and thermal distortions. It is also well suited to measure transient effects.

  5. Electro-Optical Sensor Fabricated Using a Bulk Cleavage Technique and Its Characteristics for Near-Field Intra-Body Communication

    NASA Astrophysics Data System (ADS)

    Furuya, Akinori; Sasaki, Ai-ichiro; Morimura, Hiroki; Aihara, Kimihisa; Shinagawa, Mitsuru

    2013-09-01

    This paper describes how to obtain a low cost electro-optical (EO) sensor module for the mass production of near-field intra-body communication devices. In this study, we used a bulk cleavage technique to fabricate EO modulators without the need for any optical polishing or washing processes, and clarified the feasibility of assembling optical components using only a passive alignment technique with a compact housing.

  6. Optical addressing technique for a CMOS RAM

    NASA Technical Reports Server (NTRS)

    Wu, W. H.; Bergman, L. A.; Allen, R. A.; Johnston, A. R.

    1988-01-01

    Progress on optically addressing a CMOS RAM for a feasibility demonstration of free space optical interconnection is reported in this paper. The optical RAM chip has been fabricated and functional testing is in progress. Initial results seem promising. New design and SPICE simulation of optical gate cell (OGC) circuits have been carried out to correct the slow fall time of the 'weak pull down' OGC, which has been characterized experimentally. Methods of reducing the response times of the photodiodes and the associated circuits are discussed. Even with the current photodiode, it appears that an OGC can be designed with a performance that is compatible with a CMOS circuit such as the RAM.

  7. Towards an Accurate Alignment of the VLBI Frame and the Future Gaia Optical Frame: Global VLBI Imaging Observations of a Sample of Candidate Sources for this Alignment

    NASA Astrophysics Data System (ADS)

    Bourda, G.; Collioud, A.; Charlot, P.; Porcas, R.; Garrington, S.

    2012-12-01

    The space astrometry mission Gaia will construct a dense optical QSO-based celestial reference frame. For consistency between optical and radio positions, it will be important to align the Gaia and VLBI frames with the highest accuracy. However, the number of quasars that are bright at optical wavelengths (for the best position accuracy with Gaia), that have a compact core (to be detectable on VLBI scales), and that do not exhibit complex structures (to ensure a good astrometric quality) was found to be limited. It was then realized that the densification of the list of such objects was necessary. Therefore, we initiated a multi-step VLBI observational project, dedicated to finding additional suitable radio sources for aligning the two frames. The sample consists of ~450 optically- bright weak extragalactic radio sources, which have been selected by cross-correlating optical and radio catalogs. The initial observations, aimed at checking whether these sources are detectable with VLBI, and conducted with the European VLBI Network (EVN) in 2007, showed an excellent ~90% detection rate. The second step, dedicated to identifying the most point-like sources of the sample, by imaging their VLBI structures, was initiated in 2008. Approximately 25% of the detected targets were observed with the Global VLBI array (EVN+VLBA; Very Long Baseline Array) during a pilot imaging experiment, revealing that approximately 50% of them are point-like sources on VLBI scales. The rest of the sources were observed during three additional imaging experiments in March 2010, November 2010, and March 2011. In this paper, we present the results of these imaging campaigns and report plans for the final stage of the project, which will be dedicated to accurately measuring the VLBI position of the most point-like sources.

  8. Intraocular lens alignment from an en face optical coherence tomography image Purkinje-like method

    NASA Astrophysics Data System (ADS)

    Sun, Mengchan; de Castro, Alberto; Ortiz, Sergio; Perez-Merino, Pablo; Birkenfeld, Judith; Marcos, Susana

    2014-06-01

    Measurement of intraocular lens (IOL) alignment implanted in patients in cataract surgery is important to understand their optical performance. We present a method to estimate tilt and decentration of IOLs based on optical coherence tomography (OCT) images. En face OCT images show Purkinje-like images that correspond to the specular reflections from the corneal and IOL surfaces. Unlike in standard Purkinje-imaging, the tomographic nature of OCT allows unequivocal association of the reflection with the corresponding surface. The locations of the Purkinje-like images are linear combinations of IOL tilt, IOL decentration, and eye rotation. The weighting coefficients depend on the individual anterior segment geometry, obtained from the same OCT datasets. The methodology was demonstrated on an artificial model eye with set amounts of lens tilt and decentration and five pseudophakic eyes. Measured tilt and decentration in the artificial eye differed by 3.7% and 0.9%, respectively, from nominal values. In patients, average IOL tilt and decentration from Purkinje were 3.30±4.68 deg and 0.16±0.16 mm, respectively, and differed on average by 0.5 deg and 0.09 mm, respectively, from direct measurements on distortion-corrected OCT images. Purkinje-based methodology from anterior segment en face OCT imaging provided, therefore, reliable measurements of IOL tilt and decentration.

  9. James Webb Space Telescope optical simulation testbed III: first experimental results with linear-control alignment

    NASA Astrophysics Data System (ADS)

    Egron, Sylvain; Lajoie, Charles-Philippe; Leboulleux, Lucie; N'Diaye, Mamadou; Pueyo, Laurent; Choquet, Élodie; Perrin, Marshall D.; Ygouf, Marie; Michau, Vincent; Bonnefois, Aurélie; Fusco, Thierry; Escolle, Clément; Ferrari, Marc; Hugot, Emmanuel; Soummer, Rémi

    2016-07-01

    The James Webb Space Telescope (JWST) Optical Simulation Testbed (JOST) is a tabletop experiment designed to study wavefront sensing and control for a segmented space telescope, including both commissioning and maintenance activities. JOST is complementary to existing testbeds for JWST (e.g. the Ball Aerospace Testbed Telescope TBT) given its compact scale and flexibility, ease of use, and colocation at the JWST Science and Operations Center. The design of JOST reproduces the physics of JWST's three-mirror anastigmat (TMA) using three custom aspheric lenses. It provides similar quality image as JWST (80% Strehl ratio) over a field equivalent to a NIRCam module, but at 633 nm. An Iris AO segmented mirror stands for the segmented primary mirror of JWST. Actuators allow us to control (1) the 18 segments of the segmented mirror in piston, tip, tilt and (2) the second lens, which stands for the secondary mirror, in tip, tilt and x, y, z positions. We present the full linear control alignment infrastructure developed for JOST, with an emphasis on multi-field wavefront sensing and control. Our implementation of the Wavefront Sensing (WFS) algorithms using phase diversity is experimentally tested. The wavefront control (WFC) algorithms, which rely on a linear model for optical aberrations induced by small misalignments of the three lenses, are tested and validated on simulations.

  10. Antifouling leaching technique for optical lenses

    USGS Publications Warehouse

    Strahle, William J.; Perez, C. L.; Martini, Marinna A.

    1994-01-01

    The effectiveness of optical lenses deployed in water less than 100 m deep is significantly reduced by biofouling caused by the settlement of macrofauna, such as barnacles, hydroids, and tunicates. However, machineable porous plastic rings can be used to dispense antifoulant into the water in front of the lens to retard macrofaunal growth without obstructing the light path. Unlike coatings which can degrade the optical performance, antifouling rings do not interfere with the instrument optics. The authors have designed plastic, reusable cup-like antifouling rings to slip over the optical lenses of a transmissometer. These rings have been used for several deployments on shallow moorings in Massachusetts Bay, MA and have increased the time before fouling degrades optical characteristics

  11. Fabrication, measurement, and alignment uniformity analysis of linear arrays of optical fibers

    SciTech Connect

    Klingsporn, P.E.

    1997-06-01

    Techniques were developed for assembling a linear array of optical fibers between two silicon plates and polishing the fiber ends in a plane perpendicular to the fiber axis. The silicon plates contained etched V-grooves for capturing the fibers. Optical fibers from two sources were evaluated, along with silicon plates supplied by two sources. Most of the arrays were assembled by epoxy bonding, but some effort was made to form a eutectic bond using gold metallized fibers with gold-coated silicon plates. Measurements were made of the uniformity of spacing of the fiber mode field centers in the linear array. The work was performed to develop a multi-fiber linear array connector to couple optical signals to and from optoelectronic devices.

  12. Texture evolution of vertically aligned biaxial tungsten nanorods using RHEED surface pole figure technique.

    PubMed

    Krishnan, R; Liu, Y; Gaire, C; Chen, L; Wang, G-C; Lu, T-M

    2010-08-13

    Vertically aligned biaxial tungsten nanorods with cubic A15 crystal structure were deposited by DC magnetron sputtering on native oxide covered Si(100) substrates with glancing angle flux incidence (theta approximately 85 degrees) and a two-step substrate rotation mode at room temperature. These vertical nanorods were grown to different thicknesses (10, 25, 50 and 100 nm) and analyzed for biaxial texture evolution using a highly surface sensitive reflection high-energy electron diffraction (RHEED) pole figure technique. The initial polycrystalline film begins to show the inception of biaxial texture with a fiber background between 10 and 25 nm. Biaxial texture development is eventually completed between 50 and 100 nm thicknesses of the film. The out-of-plane crystallographic direction is [002] and the in-plane texture is selected so as to obtain maximum capture area. In a comparison with 100 nm thick inclined tungsten nanorods deposited at 85 degrees without substrate rotation, it is found that the selection of in-plane texture does not maintain maximum in-plane capture area. This anomalous behavior is observed when the [002] texture axis is tilted approximately 17 degrees from the substrate normal in the direction towards the glancing incident flux.

  13. Nova laser alignment control system

    SciTech Connect

    Van Arsdall, P.J.; Holloway, F.W.; McGuigan, D.L.; Shelton, R.T.

    1984-03-29

    Alignment of the Nova laser requires control of hundreds of optical components in the ten beam paths. Extensive application of computer technology makes daily alignment practical. The control system is designed in a manner which provides both centralized and local manual operator controls integrated with automatic closed loop alignment. Menudriven operator consoles using high resolution color graphics displays overlaid with transport touch panels allow laser personnel to interact efficiently with the computer system. Automatic alignment is accomplished by using image analysis techniques to determine beam references points from video images acquired along the laser chain. A major goal of the design is to contribute substantially to rapid experimental turnaround and consistent alignment results. This paper describes the computer-based control structure and the software methods developed for aligning this large laser system.

  14. Highly Aligned Poly(vinylidene fluoride-co-hexafluoro propylene) Nanofibers via Electrospinning Technique.

    PubMed

    Han, Tae-Hwan; Nirmala, R; Kim, Tae Woo; Navamathavan, R; Kim, Hak Yong; Park, Soo Jin

    2016-01-01

    We report on the simple way of obtaining aligned poly(vinylidiene fluoride-co-hexafluoropropylene) (PVDF-HFP) nanofibers by electrospinning process. The collector drum rotation speed was adjusted to prepare well aligned PVDF-HFP nanofibers. The degree of alignment and the orientation of PVDF-HFP nanofibers can be significantly altered by varying the speed of collector drum rotation. The resultant PVDF-HFP nanofibers were systematically characterized. From the scanning electron microscopy data, it was found that the electrospun PVDF-HFP nanofibers were formed with well-aligned nature. The X-ray diffraction results revealed that the electrospun PVDF-HFP nanofibers with β-phase can be formed by the increased collector drum rotation speed. Overall, the collector rotation speed during the electrospinning process plays an important role in obtaining well-aligned and improved characteristics of PVDF-HFP nanofibers.

  15. Optical fiber sensor technique for strain measurement

    DOEpatents

    Butler, Michael A.; Ginley, David S.

    1989-01-01

    Laser light from a common source is split and conveyed through two similar optical fibers and emitted at their respective ends to form an interference pattern, one of the optical fibers having a portion thereof subjected to a strain. Changes in the strain cause changes in the optical path length of the strain fiber, and generate corresponding changes in the interference pattern. The interference pattern is received and transduced into signals representative of fringe shifts corresponding to changes in the strain experienced by the strained one of the optical fibers. These signals are then processed to evaluate strain as a function of time, typical examples of the application of the apparatus including electrodeposition of a metallic film on a conductive surface provided on the outside of the optical fiber being strained, so that strains generated in the optical fiber during the course of the electrodeposition are measurable as a function of time. In one aspect of the invention, signals relating to the fringe shift are stored for subsequent processing and analysis, whereas in another aspect of the invention the signals are processed for real-time display of the strain changes under study.

  16. Optical alignment of the Chromospheric Lyman-Alpha Spectro-Polarimeter using sophisticated methods to minimize activities under vacuum

    NASA Astrophysics Data System (ADS)

    Giono, G.; Katsukawa, Y.; Ishikawa, R.; Narukage, N.; Kano, R.; Kubo, M.; Ishikawa, S.; Bando, T.; Hara, H.; Suematsu, Y.; Winebarger, A.; Kobayashi, K.; Auchère, F.; Trujillo Bueno, J.

    2016-07-01

    The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding-rocket instrument developed at the National Astronomical Observatory of Japan (NAOJ) as a part of an international collaboration. The instrument main scientific goal is to achieve polarization measurement of the Lyman-α line at 121.56 nm emitted from the solar upper-chromosphere and transition region with an unprecedented 0.1% accuracy. The optics are composed of a Cassegrain telescope coated with a "cold mirror" coating optimized for UV reflection and a dual-channel spectrograph allowing for simultaneous observation of the two orthogonal states of polarization. Although the polarization sensitivity is the most important aspect of the instrument, the spatial and spectral resolutions of the instrument are also crucial to observe the chromospheric features and resolve the Ly-α profiles. A precise alignment of the optics is required to ensure the resolutions, but experiments under vacuum conditions are needed since Ly-α is absorbed by air, making the alignment experiments difficult. To bypass this issue, we developed methods to align the telescope and the spectrograph separately in visible light. We explain these methods and present the results for the optical alignment of the CLASP telescope and spectrograph. We then discuss the combined performances of both parts to derive the expected resolutions of the instrument, and compare them with the flight observations performed on September 3rd 2015.

  17. Optical Alignment of the Chromospheric Lyman-Alpha SpectroPolarimeter using Sophisticated Methods to Minimize Activities under Vacuum

    NASA Technical Reports Server (NTRS)

    Giono, G.; Katsukawa, Y.; Ishikawa, R.; Narukage, N.; Kano, R.; Kubo, M.; Ishikawa, S.; Bando, T.; Hara, H.; Suematsu, Y.; Winebarger, A.; Kobayashi, K.

    2016-01-01

    The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding-rocket instrument developed at the National Astronomical Observatory of Japan (NAOJ) as a part of an international collaboration. The in- strument main scientific goal is to achieve polarization measurement of the Lyman-alpha line at 121.56 nm emitted from the solar upper-chromosphere and transition region with an unprecedented 0.1% accuracy. For this purpose, the optics are composed of a Cassegrain telescope coated with a "cold mirror" coating optimized for UV reflection and a dual-channel spectrograph allowing for simultaneous observation of the two orthogonal states of polarization. Although the polarization sensitivity is the most important aspect of the instrument, the spatial and spectral resolutions of the instrument are also crucial to observe the chromospheric features and resolve the Ly- pro les. A precise alignment of the optics is required to ensure the resolutions, but experiments under vacuum conditions are needed since Ly-alpha is absorbed by air, making the alignment experiments difficult. To bypass this issue, we developed methods to align the telescope and the spectrograph separately in visible light. We will explain these methods and present the results for the optical alignment of the CLASP telescope and spectrograph. We will then discuss the combined performances of both parts to derive the expected resolutions of the instrument, and compare them with the flight observations performed on September 3rd 2015.

  18. Monolayer alignment on azobenzene surfaces during UV light irradiation: Analysis of optical polarized absorption measurement results and theoretical treatment

    SciTech Connect

    Zakharov, A.V.; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

    2006-01-14

    The influence of the charge separation during the trans-cis conformational change on the surface of azobenzene 6Az10PVA monolayer on the polar liquid-crystal monolayer film, such as 4-n-pentyl-4{sup '}-cyanobiphenyl(5CB), is investigated. The effective anchoring energy (in the Rapini-Papolar form) is phenomenologically described in the framework of the molecular model, which takes into account the interaction between the surface polarization and surface electric field, for number of conformational states of the boundary surface. It is shown, using the experimental data for the voltage across the 6Az10PVA+5CB film, provided by the surface-potential technique, that the charge separation during the conformational changing, caused by the UV irradiation, may lead to changing of the surface alignment of liquid-crystalline molecules. The influence of the photoisomerization process on the orientational order parameter S{sub 2}(t) using the optical polarized absorption measurement is also investigated.

  19. Optical Techniques for Space Environment Management

    NASA Astrophysics Data System (ADS)

    Greene, B.; Bennett, J.; Smith, C.

    2016-09-01

    The Space Environment Research Centre (SERC) is a fully-funded multi-national research collaboration for the management and mitigation of space debris using optical technologies. SERC is tasked with developing mitigation strategies for the many debris objects not amenable to space-based interventions. SERC research leverages very accurate information from a new optical space tracking network to develop viable near-term strategies to manage debris using only ground-based infrastructure. SERC has sufficient resources to conduct full-scale on-orbit testing of candidate approaches. We report on SERC progress in astrodynamics, precision catalogs, conjunction processing, adaptive optics and high power lasers as well as the architecture of the research effort.

  20. A Study of Synchronization Techniques for Optical Communication Systems

    NASA Technical Reports Server (NTRS)

    Gagliardi, R. M.

    1975-01-01

    The study of synchronization techniques and related topics in the design of high data rate, deep space, optical communication systems was reported. Data cover: (1) effects of timing errors in narrow pulsed digital optical systems, (2) accuracy of microwave timing systems operating in low powered optical systems, (3) development of improved tracking systems for the optical channel and determination of their tracking performance, (4) development of usable photodetector mathematical models for application to analysis and performance design in communication receivers, and (5) study application of multi-level block encoding to optical transmission of digital data.

  1. Building blocks for actively-aligned micro-optical systems in rapid prototyping and small series production

    NASA Astrophysics Data System (ADS)

    Böttger, Gunnar; Queisser, Marco; Arndt-Staufenbiel, Norbert; Schröder, Henning; Lang, K.-D.

    2015-03-01

    In recent years there has been considerable progress in utilizing fully automated machines for the assembly of microoptical systems. Such systems integrate laser sources, optical elements and detectors into tight packages, and efficiently couple light to free space beams, waveguides in optical backplanes, or optical fibers for longer reach transmission. The required electrical-optical and optical components are placed and aligned actively in more than one respect. For one, all active components are actually operated in the alignment process, and, more importantly, the placing of all components is controlled actively by camera systems and power detectors with live feedback for an optimal coupling efficiency. The total number of optical components typically is in the range of 5 to 50, whereas the number of actors with gripping tools for the actual handling and aligning is limited, with little flexibility in the gripping width. The assembly process therefore is strictly sequential and, given that an automated tool changing has not been established in this class of machines yet, there are either limitations in the geometries of components that may be used, or time-consuming interaction by human operators is needed. As a solution we propose and present lasered glass building blocks with standardized gripping geometries that enclose optical elements of various shapes and functionalities. These are cut as free form geometries with green short pulse and CO2 lasers. What seems to add cost at first rather increases freedom of design and adds an economical flexibility to create very hybrid assemblies of various micro-optical assemblies also in small numbers.

  2. Real-Time Optical Image Processing Techniques

    DTIC Science & Technology

    1988-10-31

    fgt modulator (LCTV SLMA" multple-focus holographic lens Jeffrey A. Davis. MEMBER SPIE ( hololens ) associative refrievot realtime robotic visWiL...above is used as an electronicallyI addressed SIM. Tswo multiple-focus holographic lenses ( hololenses ).* MHLI and MHL2. are used as space-variant optical

  3. Antares beam-alignment-system performance

    SciTech Connect

    Appert, Q.D.; Bender, S.C.

    1983-01-01

    The beam alignment system for the 24-beam-sector Antares CO/sub 2/ fusion laser automatically aligns more than 200 optical elements. A visible-wavelength alignment technique is employed which uses a telescope/TV system to view point-light sources appropriately located down the beamline. The centroids of the light spots are determined by a video tracker, which generates error signals used by the computer control system to move appropriate mirrors in a closed-loop system. Final touch-up alignment is accomplished by projecting a CO/sub 2/ alignment laser beam through the system and sensing its position at the target location. The techniques and control algorithms employed have resulted in alignment accuracies exceeding design requirements. By employing video processing to determine the centroids of diffraction images and by averaging over multiple TV frames, we achieve alignment accuracies better than 0.1 times system diffraction limits in the presence of air turbulence.

  4. Interference cancellation technique of optical AND gate receiver using optical thyristor.

    PubMed

    Kang, Tae-Gu

    2008-09-01

    We demonstrate an interference cancellation technique of optical AND gate receiver using optical thyristor for fiber-optic code division multiple access (FO-CDMA) systems. In particular, we fabricate the optical thyristor operating as optical hard-limiter and evaluate that the optical AND gate receiver using fabricated optical thyristor excludes the peaks of side-lobe and cross-correlation result in the system performance degradation. It found that the optical AND gate receiver using optical thyristor excludes the intensity of interference signal resulting in that the peaks of side-lobe and cross-correlation can be fully eliminated for any two users. Therefore, the optical AND gate receiver using optical thyristor is shown to be effective to accommodate more simultaneous users.

  5. Optical Techniques for the Remote Detection of Biological Aerosols

    DTIC Science & Technology

    1974-08-01

    enhancement of Raman or fluorescent signals, and multiwavelength differential. absorption. As will be evident from the discussions in subsequent sections of...detection of aerosols, using optical techniques. B. Rationale SRI Proposal ERU 72-62, which led to this project, describes several optical...enhancement of Raman or fluorescent signals, and multiwavelength differential absorption. The optical interactions were reviewed early in the project, with

  6. Sixport technique for phase measurement of guided optical fields

    NASA Astrophysics Data System (ADS)

    Molina-Fernandez, I.; Ortega-Moñux, A.; Halir, R.; Wangüemert-Pérez, J. G.; Perez-Lara, P.

    2010-04-01

    This paper introduces the sixport technique for precise amplitude and phase measurement of guided optical fields. The main theoretical advances in this topic are reviewed and recent experimental measurements of a Silicon on Insulator sixport PLC reflectometer are presented.

  7. (Optical characterization techniques applied to ceramic oxides)

    SciTech Connect

    Abraham, M.M.

    1990-10-15

    The traveler collaborated with M.J.M. Leask, J.M. Baker, B. Bleaney, and others at the Clarendon Laboratory, Oxford University, Oxford, UK, to Study Tetragonal rare-earth phosphates and vanadates by optical and magnetic spectroscopy. This work is related to similar studies that have been performed at ORNL by the Synthesis and Properties of Novel Materials Group in the Solid State Division.

  8. Replication of self-centering optical fiber alignment structures using hot embossing

    NASA Astrophysics Data System (ADS)

    Ebraert, Evert; Wissmann, Markus; Barié, Nicole; Guttmann, Markus; Schneider, Marc; Kolew, Alexander; Worgull, Matthias; Beri, Stefano; Watté, Jan; Thienpont, Hugo; Van Erps, Jürgen

    2016-04-01

    With the demand for broadband connectivity on the rise due to various services like video-on-demand and cloud computing becoming more popular, the need for better connectivity infrastructure is high. The only future- proof option to supply this infrastructure is to deploy "fiber to the home" (FTTH) networks. One of the main difficulties with the deployment of FTTH is the vast amount of single-mode fiber (SMF) connections that need to be made. Hence there is a strong need for components which enable high performance, robust and easy-to- use SMF connectors. Since large-scale deployment is the goal, these components should be mass-producible at low cost. We discuss a rapid prototyping process on the basis of hot embossing replication of a self-centering alignment system (SCAS) based on three micro-springs, which can position a SMF independently of its diameter. This is beneficial since there is a fabrication tolerance of up to +/-1 μm on a standard G.652 SMF's diameter that can lead to losses if the outer diameter is used as a reference for alignment. The SCAS is first prototyped with deep proton writing (DPW) in polymethylmethacrylate (PMMA) after which it is glued to a copper substrate with an adhesive. Using an electroforming process, a nickel block is grown over the PMMA prototype followed by mechanical finishing to fabricate a structured nickel mould insert. Even though the mould insert shows non- ideal and rounded features it is used to create PMMA replicas of the SCAS by means of hot embossing. The SCAS possesses a central opening in which a bare SMF can be clamped, which is designed with a diameter of 121 μm. PMMA replicas are dimensionally characterized using a multisensor coordinate measurement machine and show a central opening diameter of 128.3 +/- 2.8 μm. This should be compared to the central opening diameter of the DPW prototype used for mould formation which was measured to be 120.5 μm. This shows that the electroforming and subsequent replication

  9. Stereoradiogrammetric technique for estimating alignment of the joints in the hand and wrist.

    PubMed

    Runciman, R J; Bryant, J T; Small, C F; Fujita, N; Cooke, T D

    1993-03-01

    A method and apparatus for quantitative measurement of the alignment and motion of the joints of the hand in three dimensions has been developed using stereoradiogrammetric principles. Alignment in planes of flexion-extension and radial-ulnar deviation can be determined to within 2.5 degrees; rotation about the long axis of the metacarpals or phalanges is more difficult to determine, and can be measured to within 7 degrees. Stereo views subtending angles in the range of 40 degrees were found to optimize the total system accuracy.

  10. High-resolution optical spectrum characterization using optical channel estimation and spectrum stitching technique.

    PubMed

    Jin, Chao; Bao, Yuan; Li, Zhaohui; Gui, Tao; Shang, Haiyan; Feng, Xinhuan; Li, Jianping; Yi, Xingwen; Yu, Changyuan; Li, Guifang; Lu, Chao

    2013-07-01

    A technique is proposed to measure the high-resolution and wide-band characterization of amplitude, phase responses, and polarization property of optical components. This technique combines the optical spectrum stitching and optical channel estimation methods. Two kinds of fiber Bragg grating based Fabry-Perot cavities with ultrafine structures have been characterized based on this technique. By using 1024 point fast Fourier transform and a narrow linewidth, wavelength-tunable laser source, a frequency resolution of ~10 MHz is realized with an optical measurement range beyond 250 GHz.

  11. Techniques for optically compressing light intensity ranges

    DOEpatents

    Rushford, M.C.

    1989-03-28

    A pin hole camera assembly for use in viewing an object having a relatively large light intensity range, for example a crucible containing molten uranium in an atomic vapor laser isotope separator (AVLIS) system is disclosed herein. The assembly includes means for optically compressing the light intensity range appearing at its input sufficient to make it receivable and decipherable by a standard video camera. A number of different means for compressing the intensity range are disclosed. These include the use of photogray glass, the use of a pair of interference filters, and the utilization of a new liquid crystal notch filter in combination with an interference filter. 18 figs.

  12. Techniques for optically compressing light intensity ranges

    DOEpatents

    Rushford, Michael C.

    1989-01-01

    A pin hole camera assembly for use in viewing an object having a relatively large light intensity range, for example a crucible containing molten uranium in an atomic vapor laser isotope separator (AVLIS) system is disclosed herein. The assembly includes means for optically compressing the light intensity range appearing at its input sufficient to make it receivable and decipherable by a standard video camera. A number of different means for compressing the intensity range are disclosed. These include the use of photogray glass, the use of a pair of interference filters, and the utilization of a new liquid crystal notch filter in combination with an interference filter.

  13. Optical skin friction measurement technique in hypersonic wind tunnel

    NASA Astrophysics Data System (ADS)

    Chen, Xing; Yao, Dapeng; Wen, Shuai; Pan, Junjie

    2016-10-01

    Shear-sensitive liquid-crystal coatings (SSLCCs) have an optical characteristic that they are sensitive to the applied shear stress. Based on this, a novel technique is developed to measure the applied shear stress of the model surface regarding both its magnitude and direction in hypersonic flow. The system of optical skin friction measurement are built in China Academy of Aerospace Aerodynamics (CAAA). A series of experiments of hypersonic vehicle is performed in wind tunnel of CAAA. Global skin friction distribution of the model which shows complicated flow structures is discussed, and a brief mechanism analysis and an evaluation on optical measurement technique have been made.

  14. Fully passive-alignment pluggable compact parallel optical interconnection modules based on a direct-butt-coupling structure for fiber-optic applications

    NASA Astrophysics Data System (ADS)

    Lim, Kwon-Seob; Park, Hyoung-Jun; Kang, Hyun Seo; Kim, Young Sun; Jang, Jae-Hyung

    2016-02-01

    A low-cost packaging method utilizing a fully passive optical alignment and surface-mounting method is demonstrated for pluggable compact and slim multichannel optical interconnection modules using a VCSEL/PIN-PD chip array. The modules are based on a nonplanar bent right-angle electrical signal path on a silicon platform and direct-butt-optical coupling without a bulky and expensive microlens array. The measured optical direct-butt-coupling efficiencies of each channel without any bulky optics are as high as 33% and 95% for the transmitter and receiver, respectively. Excellent lateral optical alignment tolerance of larger than 60 μm for both the transmitter and receiver module significantly reduces the manufacturing and material costs as well as the packaging time. The clear eye diagrams, extinction ratios higher than 8 dB at 10.3 Gbps for the transmitter module, and receiver sensitivity of better than -13.1 dBm at 10.3 Gbps and a bit error rate of 10-12 for all channels are demonstrated. Considering that the optical output power of the transmitter is greater than 0 dBm, the module has a sufficient power margin of about 13 dB for 10.3 Gbps operations for all channels.

  15. RF Jitter Modulation Alignment Sensing

    NASA Astrophysics Data System (ADS)

    Ortega, L. F.; Fulda, P.; Diaz-Ortiz, M.; Perez Sanchez, G.; Ciani, G.; Voss, D.; Mueller, G.; Tanner, D. B.

    2017-01-01

    We will present the numerical and experimental results of a new alignment sensing scheme which can reduce the complexity of alignment sensing systems currently used, while maintaining the same shot noise limited sensitivity. This scheme relies on the ability of electro-optic beam deflectors to create angular modulation sidebands in radio frequency, and needs only a single-element photodiode and IQ demodulation to generate error signals for tilt and translation degrees of freedom in one dimension. It distances itself from current techniques by eliminating the need for beam centering servo systems, quadrant photodetectors and Gouy phase telescopes. RF Jitter alignment sensing can be used to reduce the complexity in the alignment systems of many laser optical experiments, including LIGO and the ALPS experiment.

  16. Automatic inspection technique for optical surface flaws

    NASA Astrophysics Data System (ADS)

    Yang, GuoGuang; Gao, Wenliang; Cheng, Shangyi

    1991-01-01

    Industrial inspection of optical component surface flaws requires objective, high efficient and fast measurement methods and instruments. In this paper, a novel method, which is practical for on- line inspecting optical component surface flaws in manufacturing industry, is discribed. Laser beam goes through a lean- placed mirror with a slot in center onto the surface of the specimen. The imformation of surface flaws is obtained through analysing the frequency spectrum of reflective light which is detected by a photomultiplier, the specimen scanning control and signal processing are finished by a low - cost and handy single- board microcomputer. The theory that applies the scanning frequency spectrum method , the method for determining flaw size and measuring sensitivity as well as control model for various specimen are analysed in detail .A system has been built according to the idea discribed above. By using the system, several specimen are measured, the comparison and analysis between exprimental results and actual flaw conditions are given. The minimum detectable flaw is 3 micrometer, the measuring error is also given.

  17. Real-time optical image processing techniques

    NASA Technical Reports Server (NTRS)

    Liu, Hua-Kuang

    1988-01-01

    Nonlinear real-time optical processing on spatial pulse frequency modulation has been pursued through the analysis, design, and fabrication of pulse frequency modulated halftone screens and the modification of micro-channel spatial light modulators (MSLMs). Micro-channel spatial light modulators are modified via the Fabry-Perot method to achieve the high gamma operation required for non-linear operation. Real-time nonlinear processing was performed using the halftone screen and MSLM. The experiments showed the effectiveness of the thresholding and also showed the needs of higher SBP for image processing. The Hughes LCLV has been characterized and found to yield high gamma (about 1.7) when operated in low frequency and low bias mode. Cascading of two LCLVs should also provide enough gamma for nonlinear processing. In this case, the SBP of the LCLV is sufficient but the uniformity of the LCLV needs improvement. These include image correlation, computer generation of holograms, pseudo-color image encoding for image enhancement, and associative-retrieval in neural processing. The discovery of the only known optical method for dynamic range compression of an input image in real-time by using GaAs photorefractive crystals is reported. Finally, a new architecture for non-linear multiple sensory, neural processing has been suggested.

  18. Optical techniques for shock visualization and detection

    NASA Technical Reports Server (NTRS)

    Adamovsky, G.; Johnson, D. K.

    1995-01-01

    While the classical methods of shadowgraph and schlieren do yield a shadow in the neighborhood of a shock, they often suffer from low power densities and the need for relatively long distances. Scanning methods may help in solving these problems. The paper describes various scanning techniques, presents experimental data obtained by mechanical scanning, and identifies conditions at which the data were taken.

  19. Gabor-based fusion technique for Optical Coherence Microscopy.

    PubMed

    Rolland, Jannick P; Meemon, Panomsak; Murali, Supraja; Thompson, Kevin P; Lee, Kye-sung

    2010-02-15

    We recently reported on an Optical Coherence Microscopy technique, whose innovation intrinsically builds on a recently reported - 2 microm invariant lateral resolution by design throughout a 2 mm cubic full-field of view - liquid-lens-based dynamic focusing optical probe [Murali et al., Optics Letters 34, 145-147, 2009]. We shall report in this paper on the image acquisition enabled by this optical probe when combined with an automatic data fusion method developed and described here to produce an in-focus high resolution image throughout the imaging depth of the sample. An African frog tadpole (Xenopus laevis) was imaged with the novel probe and the Gabor-based fusion technique, demonstrating subcellular resolution in a 0.5 mm (lateral) x 0.5 mm (axial) without the need, for the first time, for x-y translation stages, depth scanning, high-cost adaptive optics, or manual intervention. In vivo images of human skin are also presented.

  20. The optical manifestation of dispersive field-aligned bursts in auroral breakup arcs

    NASA Astrophysics Data System (ADS)

    Dahlgren, H.; Semeter, J. L.; Marshall, R. A.; Zettergren, M.

    2013-07-01

    High-resolution optical observations of a substorm expansion show dynamic auroral rays with surges of luminosity traveling up the magnetic field lines. Observed in ground-based imagers, this phenomenon has been termed auroral flames, whereas the rocket signatures of the corresponding energy dispersions are more commonly known as field-aligned bursts. In this paper, observations of auroral flames obtained at 50 frames/s with a scientific-grade Complementary Metal Oxide Semiconductor (CMOS) sensor (30° × 30° field of view, 30 m resolution at 120 km) are used to provide insight into the nature of the precipitating electrons similar to high-resolution particle detectors. Thanks to the large field of view and high spatial resolution of this system, it is possible to obtain a first-order estimate of the temporal evolution in altitude of the volume emission rate from a single sensor. The measured volume emission rates are compared with the sum of modeled eigenprofiles obtained for a finite set of electron beams with varying energy provided by the TRANSCAR auroral flux tube model. The energy dispersion signatures within each auroral ray can be analyzed in detail during a fraction of a second. The evolution of energy and flux of the precipitation shows precipitation spanning over a large range of energies, with the characteristic energy dropping from 2.1 keV to 0.87 keV over 0.2 s. Oscillations at 2.4 Hz in the magnetic zenith correspond to the period of the auroral flames, and the acceleration is believed to be due to Alfvenic wave interaction with electrons above the ionosphere.

  1. A Novel Scheme for DVL-Aided SINS In-Motion Alignment Using UKF Techniques

    PubMed Central

    Li, Wanli; Wang, Jinling; Lu, Liangqing; Wu, Wenqi

    2013-01-01

    In-motion alignment of Strapdown Inertial Navigation Systems (SINS) without any geodetic-frame observations is one of the toughest challenges for Autonomous Underwater Vehicles (AUV). This paper presents a novel scheme for Doppler Velocity Log (DVL) aided SINS alignment using Unscented Kalman Filter (UKF) which allows large initial misalignments. With the proposed mechanism, a nonlinear SINS error model is presented and the measurement model is derived under the assumption that large misalignments may exist. Since a priori knowledge of the measurement noise covariance is of great importance to robustness of the UKF, the covariance-matching methods widely used in the Adaptive KF (AKF) are extended for use in Adaptive UKF (AUKF). Experimental results show that the proposed DVL-aided alignment model is effective with any initial heading errors. The performances of the adaptive filtering methods are evaluated with regards to their parameter estimation stability. Furthermore, it is clearly shown that the measurement noise covariance can be estimated reliably by the adaptive UKF methods and hence improve the performance of the alignment. PMID:23322105

  2. Characterization of ultrafast devices using novel optical techniques

    NASA Astrophysics Data System (ADS)

    Ali, Md Ershad

    Optical techniques have been extensively used to examine the high frequency performance of a number of devices including High Electron Mobility Transistors (HEMTs), Heterojunction Bipolar Phototransistors (HPTs) and Low Temperature GaAs (LT-GaAs) Photoconductive Switches. To characterize devices, frequency and time domain techniques, namely optical heterodyning and electro-optic sampling, having measurement bandwidths in excess of 200 GHz, were employed. Optical mixing in three-terminal devices has been extended for the first time to submillimeter wave frequencies. Using a new generation of 50-nm gate pseudomorphic InP-based HEMTs, optically mixed signals were detected to 552 GHz with a signal-to-noise ratio of approximately 5 dB. To the best of our knowledge, this is the highest frequency optical mixing obtained in three- terminal devices to date. A novel harmonic three-wave detection scheme was used for the detection of the optically generated signals. The technique involved downconversion of the signal in the device by the second harmonic of a gate-injected millimeter wave local oscillator. Measurements were also conducted up to 212 GHz using direct optical mixing and up to 382 GHz using a fundamental three-wave detection scheme. New interesting features in the bias dependence of the optically mixed signals have been reported. An exciting novel development from this work is the successful integration of near-field optics with optical heterodyning. The technique, called near-field optical heterodyning (NFOH), allows for extremely localized injection of high-frequency stimulus to any arbitrary point of an ultrafast device or circuit. Scanning the point of injection across the sample provides details of the high frequency operation of the device with high spatial resolution. For the implementation of the technique, fiber-optic probes with 100 nm apertures were fabricated. A feedback controlled positioning system was built for accurate placement and scanning of the

  3. Optical measurement techniques for mobile and large-scale dimensional metrology

    NASA Astrophysics Data System (ADS)

    Cuypers, W.; Van Gestel, N.; Voet, A.; Kruth, J.-P.; Mingneau, J.; Bleys, P.

    2009-03-01

    Dimensional inspection tasks are often carried out on conventional coordinate measuring machines (CMMs). These CMMs can differ in layout and size depending on the application area. They can have measurement volumes up to 100 m 3. However, when measuring large objects it is not always possible to bring a large object to these conventional CMMs. That is why for these applications mobile measuring systems are an ideal solution. These systems often measure the dimensions through optical techniques, like interferometry and optical triangulation. After a short survey of common optical measurement techniques for mobile and large-scale measurements, this paper focuses on two industrial cases where different techniques were used to solve a measurement problem. The first case covers the measurement of a large iron casting with an optical LED-based triangulation system. It was possible to predict problems that would occur with the machining of the part, like unfinished surfaces after milling due to material shortage, and adapt the alignment of the part to prevent these problems. The second case covers the measurement of a double-decker train by means of photogrammetry, as an alternative for the currently used total station. Despite some specific drawbacks of photogrammetry systems it was possible to obtain the same accuracy and to reduce the overall inspection time significantly in comparison with the current situation.

  4. Field results of antifouling techniques for optical instruments

    USGS Publications Warehouse

    Strahle, W.J.; Hotchkiss, F.S.; Martini, M.A.

    1998-01-01

    An anti-fouling technique is developed for the protection of optical instruments from biofouling which leaches a bromide compound into a sample chamber and pumps new water into the chamber prior to measurement. The primary advantage of using bromide is that it is less toxic than the metal-based antifoulants. The drawback of the bromide technique is also discussed.

  5. Improved docking alignment system

    NASA Technical Reports Server (NTRS)

    Monford, Leo G. (Inventor)

    1988-01-01

    Improved techniques are provided for the alignment of two objects. The present invention is particularly suited for 3-D translation and 3-D rotational alignment of objects in outer space. A camera is affixed to one object, such as a remote manipulator arm of the spacecraft, while the planar reflective surface is affixed to the other object, such as a grapple fixture. A monitor displays in real-time images from the camera such that the monitor displays both the reflected image of the camera and visible marking on the planar reflective surface when the objects are in proper alignment. The monitor may thus be viewed by the operator and the arm manipulated so that the reflective surface is perpendicular to the optical axis of the camera, the roll of the reflective surface is at a selected angle with respect to the camera, and the camera is spaced a pre-selected distance from the reflective surface.

  6. Light deviation based optical techniques applied to solid propellant combustion

    NASA Astrophysics Data System (ADS)

    Cauty, F.; Eradès, C.; Desse, J.-M.

    2011-10-01

    The Investigation in Combustion of Energetic Materials (InCoME) program is aimed at validating the numerical simulation of composite propellant combustion using nonintrusive optical techniques. The Focusing Schlieren Technique (FST) was selected; it allows catching light deviation from a thin vertical planar section centered above the propellant combustion surface. The optical system is described in the paper. Significant results are presented showing the capabilities of this technique when applied to solid propellant combustion in terms of studying flame structure, flame propagation, and particle tracking.

  7. Method for accurate optical alignment using diffraction rings from lenses with spherical aberration.

    PubMed

    Gwynn, R B; Christensen, D A

    1993-03-01

    A useful alignment method is presented that exploits the closely spaced concentric fringes that form in the longitudinal spherical aberration region of positive spherical lenses imaging a point source. To align one or more elements to a common axis, spherical lenses are attached precisely to the elements and the resulting diffraction rings are made to coincide. We modeled the spherical aberration of the lenses by calculating the diffraction patterns of converging plane waves passing through concentric narrow annular apertures. The validity of the model is supported by experimental data and is determined to be accurate for a prototype penumbral imaging alignment system developed at Lawrence Livermore National Laboratory.

  8. Tumor margin detection using optical biopsy techniques

    NASA Astrophysics Data System (ADS)

    Zhou, Yan; Liu, Cheng-hui; Li, Jiyou; Li, Zhongwu; Zhou, Lixin; Chen, Ke; Pu, Yang; He, Yong; Zhu, Ke; Li, Qingbo; Alfano, Robert R.

    2014-03-01

    The aim of this study is to use the Resonance Raman (RR) and fluorescence spectroscopic technique for tumor margin detection with high accuracy based on native molecular fingerprints of breast and gastrointestinal (GI) tissues. This tumor margins detection method utilizes advantages of RR spectroscopic technique in situ and in real-time to diagnose tumor changes providing powerful tools for clinical guiding intraoperative margin assessments and postoperative treatments. The tumor margin detection procedures by RR spectroscopy were taken by scanning lesion from center or around tumor region in ex-vivo to find the changes in cancerous tissues with the rim of normal tissues using the native molecular fingerprints. The specimens used to analyze tumor margins include breast and GI carcinoma and normal tissues. The sharp margin of the tumor was found by the changes of RR spectral peaks within 2 mm distance. The result was verified using fluorescence spectra with 300 nm, 320 nm and 340 nm excitation, in a typical specimen of gastric cancerous tissue within a positive margin in comparison with normal gastric tissues. This study demonstrates the potential of RR and fluorescence spectroscopy as new approaches with labeling free to determine the intraoperative margin assessment.

  9. Optical techniques for time and frequency transfer

    NASA Technical Reports Server (NTRS)

    Baumont, Francoise; Gaignebet, Jean

    1994-01-01

    Light has been used as a means for time synchronization for a long time. The flight time was supposed to be negligible. The first scientific determination of the velocity of the light was done by measuring a round trip flight time on a given distance. The well known flying clock experiment leading to Einstein's General Relativity is another example. The advent of lasers, particularly short pulse and modulated ones, as well as the improvements of the timing equipments have led to new concepts for time and frequency transfer. We describe some experiments using different techniques and configurations which have been proposed and tested in this field since the beginning of the space age. Added to that, we set out advantages, drawbacks, and performances achieved in the different cases.

  10. Optical beam forming techniques for phased array antennas

    NASA Astrophysics Data System (ADS)

    Wu, Te-Kao; Chandler, C.

    Conventional phased array antennas using waveguide or coax for signal distribution are impractical for large scale implementation on satellites or spacecraft because they exhibit prohibitively large system size, heavy weight, high attenuation loss, limited bandwidth, sensitivity to electromagnetic interference (EMI) temperature drifts and phase instability. However, optical beam forming systems are smaller, lighter, and more flexible. Three optical beam forming techniques are identified as applicable to large spaceborne phased array antennas. They are (1) the optical fiber replacement of conventional RF phased array distribution and control components, (2) spatial beam forming, and (3) optical beam splitting with integrated quasi-optical components. The optical fiber replacement and the spatial beam forming approaches were pursued by many organizations. Two new optical beam forming architectures are presented. Both architectures involve monolithic integration of the antenna radiating elements with quasi-optical grid detector arrays. The advantages of the grid detector array in the optical process are the higher power handling capability and the dynamic range. One architecture involves a modified version of the original spatial beam forming approach. The basic difference is the spatial light modulator (SLM) device for controlling the aperture field distribution. The original liquid crystal light valve SLM is replaced by an optical shuffling SLM, which was demonstrated for the 'smart pixel' technology. The advantages are the capability of generating the agile beams of a phased array antenna and to provide simultaneous transmit and receive functions. The second architecture considered is the optical beam splitting approach. This architecture involves an alternative amplitude control for each antenna element with an optical beam power divider comprised of mirrors and beam splitters. It also implements the quasi-optical grid phase shifter for phase control and grid

  11. Optical beam forming techniques for phased array antennas

    NASA Technical Reports Server (NTRS)

    Wu, Te-Kao; Chandler, C.

    1993-01-01

    Conventional phased array antennas using waveguide or coax for signal distribution are impractical for large scale implementation on satellites or spacecraft because they exhibit prohibitively large system size, heavy weight, high attenuation loss, limited bandwidth, sensitivity to electromagnetic interference (EMI) temperature drifts and phase instability. However, optical beam forming systems are smaller, lighter, and more flexible. Three optical beam forming techniques are identified as applicable to large spaceborne phased array antennas. They are (1) the optical fiber replacement of conventional RF phased array distribution and control components, (2) spatial beam forming, and (3) optical beam splitting with integrated quasi-optical components. The optical fiber replacement and the spatial beam forming approaches were pursued by many organizations. Two new optical beam forming architectures are presented. Both architectures involve monolithic integration of the antenna radiating elements with quasi-optical grid detector arrays. The advantages of the grid detector array in the optical process are the higher power handling capability and the dynamic range. One architecture involves a modified version of the original spatial beam forming approach. The basic difference is the spatial light modulator (SLM) device for controlling the aperture field distribution. The original liquid crystal light valve SLM is replaced by an optical shuffling SLM, which was demonstrated for the 'smart pixel' technology. The advantages are the capability of generating the agile beams of a phased array antenna and to provide simultaneous transmit and receive functions. The second architecture considered is the optical beam splitting approach. This architecture involves an alternative amplitude control for each antenna element with an optical beam power divider comprised of mirrors and beam splitters. It also implements the quasi-optical grid phase shifter for phase control and grid

  12. Polymer waveguides self-organized by two-photon photochemistry for self-aligned optical couplings with wide misalignment tolerances

    NASA Astrophysics Data System (ADS)

    Yoshimura, Tetsuzo; Takeda, Daisuke; Sato, Takuya; Kinugasa, Yoshihiko; Nawata, Hideyuki

    2016-03-01

    Self-organized optical waveguides formed in a photopolymer using two-photon photochemistry is proposed for self-aligned optical couplings involving nano-scale optical devices with wide tolerances in lateral misalignments. Simulations based on the finite-difference time-domain method revealed that on introducing a 400-nm write beam and a 780-nm write beam into the two-photon photopolymer respectively from two 600-nm-wide waveguides facing each other with 32 μm gap a self-aligned coupling waveguide called a two-photon self-organized lightwave network (SOLNET) is formed between the two waveguides. The lateral misalignment tolerance was found to be 3000 nm, which is five times larger than the misalignment limit of ~600 nm in waveguides formed by conventional one-photon photochemistry. Preliminary experiments demonstrated that the two-photon SOLNETs are formed between multimode optical fibers by introducing a 448-nm write beam and a 780-nm (or 856-nm) write beam from the fibers into a photosensitive organic/inorganic hybrid material, SUNCONNECT®, with doped camphorquinone (or biacetyl).

  13. Nanoscale optical and electrical characterization of horizontally aligned single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Rodriguez, Raul D.; Toader, Marius; Hermann, Sascha; Sheremet, Evgeniya; Müller, Susanne; Gordan, Ovidiu D.; Yu, Haibo; Schulz, Stefan E.; Hietschold, Michael; Zahn, Dietrich RT

    2012-12-01

    During the recent years, a significant amount of research has been performed on single-walled carbon nanotubes (SWCNTs) as a channel material in thin-film transistors (Pham et al. IEEE Trans Nanotechnol 11:44-50, 2012). This has prompted the application of advanced characterization techniques based on combined atomic force microscopy (AFM) and Raman spectroscopy studies (Mureau et al. Electrophoresis 29:2266-2271, 2008). In this context, we use confocal Raman microscopy and current sensing atomic force microscopy (CS-AFM) to study phonons and the electronic transport in semiconducting SWCNTs, which were aligned between palladium electrodes using dielectrophoresis (Kuzyk Electrophoresis 32:2307-2313, 2011). Raman imaging was performed in the region around the electrodes on the suspended CNTs using several laser excitation wavelengths. Analysis of the G+/G- splitting in the Raman spectra (Sgobba and Guldi Chem Soc Rev 38:165-184, 2009) shows CNT diameters of 2.5 ± 0.3 nm. Neither surface modification nor increase in defect density or stress at the CNT-electrode contact could be detected, but rather a shift in G+ and G- peak positions in regions with high CNT density between the electrodes. Simultaneous topographical and electrical characterization of the CNT transistor by CS-AFM confirms the presence of CNT bundles having a stable electrical contact with the transistor electrodes. For a similar load force, reproducible current-voltage ( I/ V) curves for the same CNT regions verify the stability of the electrical contact between the nanotube and the electrodes as well as the nanotube and the AFM tip over different experimental sessions using different AFM tips. Strong variations observed in the I/ V response at different regions of the CNT transistor are discussed.

  14. Nanoscale optical and electrical characterization of horizontally aligned single-walled carbon nanotubes

    PubMed Central

    2012-01-01

    During the recent years, a significant amount of research has been performed on single-walled carbon nanotubes (SWCNTs) as a channel material in thin-film transistors (Pham et al. IEEE Trans Nanotechnol 11:44–50, 2012). This has prompted the application of advanced characterization techniques based on combined atomic force microscopy (AFM) and Raman spectroscopy studies (Mureau et al. Electrophoresis 29:2266–2271, 2008). In this context, we use confocal Raman microscopy and current sensing atomic force microscopy (CS-AFM) to study phonons and the electronic transport in semiconducting SWCNTs, which were aligned between palladium electrodes using dielectrophoresis (Kuzyk Electrophoresis 32:2307–2313, 2011). Raman imaging was performed in the region around the electrodes on the suspended CNTs using several laser excitation wavelengths. Analysis of the G+/G− splitting in the Raman spectra (Sgobba and Guldi Chem Soc Rev 38:165–184, 2009) shows CNT diameters of 2.5 ± 0.3 nm. Neither surface modification nor increase in defect density or stress at the CNT-electrode contact could be detected, but rather a shift in G+ and G− peak positions in regions with high CNT density between the electrodes. Simultaneous topographical and electrical characterization of the CNT transistor by CS-AFM confirms the presence of CNT bundles having a stable electrical contact with the transistor electrodes. For a similar load force, reproducible current–voltage (I/V) curves for the same CNT regions verify the stability of the electrical contact between the nanotube and the electrodes as well as the nanotube and the AFM tip over different experimental sessions using different AFM tips. Strong variations observed in the I/V response at different regions of the CNT transistor are discussed. PMID:23259903

  15. Nanoscale optical and electrical characterization of horizontally aligned single-walled carbon nanotubes.

    PubMed

    Rodriguez, Raul D; Toader, Marius; Hermann, Sascha; Sheremet, Evgeniya; Müller, Susanne; Gordan, Ovidiu D; Yu, Haibo; Schulz, Stefan E; Hietschold, Michael; Zahn, Dietrich Rt

    2012-12-21

    During the recent years, a significant amount of research has been performed on single-walled carbon nanotubes (SWCNTs) as a channel material in thin-film transistors (Pham et al. IEEE Trans Nanotechnol 11:44-50, 2012). This has prompted the application of advanced characterization techniques based on combined atomic force microscopy (AFM) and Raman spectroscopy studies (Mureau et al. Electrophoresis 29:2266-2271, 2008). In this context, we use confocal Raman microscopy and current sensing atomic force microscopy (CS-AFM) to study phonons and the electronic transport in semiconducting SWCNTs, which were aligned between palladium electrodes using dielectrophoresis (Kuzyk Electrophoresis 32:2307-2313, 2011). Raman imaging was performed in the region around the electrodes on the suspended CNTs using several laser excitation wavelengths. Analysis of the G+/G- splitting in the Raman spectra (Sgobba and Guldi Chem Soc Rev 38:165-184, 2009) shows CNT diameters of 2.5 ± 0.3 nm. Neither surface modification nor increase in defect density or stress at the CNT-electrode contact could be detected, but rather a shift in G+ and G- peak positions in regions with high CNT density between the electrodes. Simultaneous topographical and electrical characterization of the CNT transistor by CS-AFM confirms the presence of CNT bundles having a stable electrical contact with the transistor electrodes. For a similar load force, reproducible current-voltage (I/V) curves for the same CNT regions verify the stability of the electrical contact between the nanotube and the electrodes as well as the nanotube and the AFM tip over different experimental sessions using different AFM tips. Strong variations observed in the I/V response at different regions of the CNT transistor are discussed.

  16. High-performance partially aligned semiconductive single-walled carbon nanotube transistors achieved with a parallel technique.

    PubMed

    Wang, Yilei; Pillai, Suresh Kumar Raman; Chan-Park, Mary B

    2013-09-09

    Single-walled carbon nanotubes (SWNTs) are widely thought to be a strong contender for next-generation printed electronic transistor materials. However, large-scale solution-based parallel assembly of SWNTs to obtain high-performance transistor devices is challenging. SWNTs have anisotropic properties and, although partial alignment of the nanotubes has been theoretically predicted to achieve optimum transistor device performance, thus far no parallel solution-based technique can achieve this. Herein a novel solution-based technique, the immersion-cum-shake method, is reported to achieve partially aligned SWNT networks using semiconductive (99% enriched) SWNTs (s-SWNTs). By immersing an aminosilane-treated wafer into a solution of nanotubes placed on a rotary shaker, the repetitive flow of the nanotube solution over the wafer surface during the deposition process orients the nanotubes toward the fluid flow direction. By adjusting the nanotube concentration in the solution, the nanotube density of the partially aligned network can be controlled; linear densities ranging from 5 to 45 SWNTs/μm are observed. Through control of the linear SWNT density and channel length, the optimum SWNT-based field-effect transistor devices achieve outstanding performance metrics (with an on/off ratio of ~3.2 × 10(4) and mobility 46.5 cm(2) /Vs). Atomic force microscopy shows that the partial alignment is uniform over an area of 20 × 20 mm(2) and confirms that the orientation of the nanotubes is mostly along the fluid flow direction, with a narrow orientation scatter characterized by a full width at half maximum (FWHM) of <15° for all but the densest film, which is 35°. This parallel process is large-scale applicable and exploits the anisotropic properties of the SWNTs, presenting a viable path forward for industrial adoption of SWNTs in printed, flexible, and large-area electronics.

  17. Neurovascular coupling: in vivo optical techniques for functional brain imaging

    PubMed Central

    2013-01-01

    Optical imaging techniques reflect different biochemical processes in the brain, which is closely related with neural activity. Scientists and clinicians employ a variety of optical imaging technologies to visualize and study the relationship between neurons, glial cells and blood vessels. In this paper, we present an overview of the current optical approaches used for the in vivo imaging of neurovascular coupling events in small animal models. These techniques include 2-photon microscopy, laser speckle contrast imaging (LSCI), voltage-sensitive dye imaging (VSDi), functional photoacoustic microscopy (fPAM), functional near-infrared spectroscopy imaging (fNIRS) and multimodal imaging techniques. The basic principles of each technique are described in detail, followed by examples of current applications from cutting-edge studies of cerebral neurovascular coupling functions and metabolic. Moreover, we provide a glimpse of the possible ways in which these techniques might be translated to human studies for clinical investigations of pathophysiology and disease. In vivo optical imaging techniques continue to expand and evolve, allowing us to discover fundamental basis of neurovascular coupling roles in cerebral physiology and pathophysiology. PMID:23631798

  18. Neurovascular coupling: in vivo optical techniques for functional brain imaging.

    PubMed

    Liao, Lun-De; Tsytsarev, Vassiliy; Delgado-Martínez, Ignacio; Li, Meng-Lin; Erzurumlu, Reha; Vipin, Ashwati; Orellana, Josue; Lin, Yan-Ren; Lai, Hsin-Yi; Chen, You-Yin; Thakor, Nitish V

    2013-04-30

    Optical imaging techniques reflect different biochemical processes in the brain, which is closely related with neural activity. Scientists and clinicians employ a variety of optical imaging technologies to visualize and study the relationship between neurons, glial cells and blood vessels. In this paper, we present an overview of the current optical approaches used for the in vivo imaging of neurovascular coupling events in small animal models. These techniques include 2-photon microscopy, laser speckle contrast imaging (LSCI), voltage-sensitive dye imaging (VSDi), functional photoacoustic microscopy (fPAM), functional near-infrared spectroscopy imaging (fNIRS) and multimodal imaging techniques. The basic principles of each technique are described in detail, followed by examples of current applications from cutting-edge studies of cerebral neurovascular coupling functions and metabolic. Moreover, we provide a glimpse of the possible ways in which these techniques might be translated to human studies for clinical investigations of pathophysiology and disease. In vivo optical imaging techniques continue to expand and evolve, allowing us to discover fundamental basis of neurovascular coupling roles in cerebral physiology and pathophysiology.

  19. A novel technique for an integrated optical wavelength demultiplexer

    NASA Astrophysics Data System (ADS)

    Lotfy Rabeh, M.; Mohanna, M.; Hosny, Tarek; Gabr, Mohamed I.

    2015-12-01

    In this paper we propose a new technique for optical wavelength demultiplexing (DEMUX) relaying on two phenomena: Goos-Haenchen (GH) shift and continuous refraction at a graded-index medium interface. In the first case, two light beams are totally reflected at a plane interface separating two dielectric lossless media. The reflected beams suffer different lateral shifts (GH shifts) depending on the wavelength; thus accomplishing the required spatial beam separation. In the second case, the two light beams have different "turning points" inside the graded index medium; hence, the "back-refracted" beams are spatially separated. In this paper, we optimized the conditions of operation of such demultiplexing technique. This makes possible the integration of such technique in "planar integrated-optics" structures which can be used reliably in optical fiber communication networks.

  20. Optical Performance Evaluation and Aligning Method for Solid Immersion Lens Assembly with Wedge Plate Lateral Shearing Interferometer

    NASA Astrophysics Data System (ADS)

    Lee, Jin-Eui; Kim, Wan-Chin; Kim, Tae-Seob; Choi, Hyun; Yoon, Yong-Joong; Park, No-Cheol; Park, Young-Pil

    2007-08-01

    We present a simple and stable optical performance evaluation and aligning method for a solid immersion lens (SIL) assembly with a wedge plate lateral shearing interferometer (LSI). There are many advantages in the use of the wedge plate LSI compared with a current SIL measurement method using a Twyman-Green interferometer. We designed the thicknesses, wedge angles, materials, and reflectances of the first and second surfaces of the wedge plate to be 1 mm, 0.02°, fused silica and 21, and 30%, respectively. Simulation and experimental results are well matched in quantitative analyses at shear ratios of 10, 40, and 70%. On the basis of simulation results for an aberrated SIL assembly with many misaligned cases, we suggested the use of the aligning process with the wedge plate LSI.

  1. Shape control of modular x-ray optics during integration and alignment: concepts and recent experiments at MPE

    NASA Astrophysics Data System (ADS)

    Breunig, E.; Friedrich, P.; Winter, A.

    2013-09-01

    Large modular optics made of thousands of mirror segments are a cornerstone of future x-ray mission concepts. In this project we focus on the integration and alignment of slumped glass wolter-1 segments into a mirror module. The two key issues of concern are the handling of a mirror segment during assembly, and the technology to permanently integrate the mirror segments with the supporting mirror module. Both steps can introduce significant shape error to the mirror. Our approach is based on the principle of minimizing distortions to the mirror by using a gravity compliand alignment setup and optimized interfaces. This paper is focused on basic requirements and recent integration experiments, of which analysis and results will be shown and future development discussed.

  2. Active optical alignment of off-axis telescopes based on nodal aberration theory.

    PubMed

    Zhang, Xiaobin; Zhang, Dong; Xu, Shuyan; Ma, Hongcai

    2016-11-14

    Our paper mainly separates the specific aberration contributions of third-order astigmatism and third-order coma from the total aberration fields, on the framework of the modified nodal aberration theory (NAT), for the perturbed off-axis telescope. Based on the derived aberration functions, two alignment models for the same off-axis two-mirror telescope are established and compared. Among them, one is based on third-order NAT, the other is based on fifth-order NAT. By comparison, it is found that the calculated perturbations based on fifth-order NAT are more accurate. It illustrates that third-order astigmatism and third-order coma contributed from fifth-order aberrations can't be neglected in the alignment process. Then the fifth-order NAT is used for the alignment of off-axis three-mirror telescopes. After simulation, it is found that the perturbed off-axis three-mirror telescope can be perfectly aligned as well. To further demonstrate the application of the alignment method based on fifth-order NAT (simplified as NAT method), Monte-Carlo simulations for both off-axis two-mirror telescope and off-axis three-mirror telescope are conducted in the end. Meantime, a comparison between NAT method and sensitivity table method is also conducted. It is proven that the computation accuracy of NAT method is much higher, especially in poor conditions.

  3. Optical frequency upconversion technique for transmission of wireless MIMO-type signals over optical fiber.

    PubMed

    Shaddad, R Q; Mohammad, A B; Al-Gailani, S A; Al-Hetar, A M

    2014-01-01

    The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio-over-fiber (ROF) technique. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as wireless multi-input multi-output (MIMO) signals feeding multiple antennas in the fiber wireless (FiWi) system. A novel optical frequency upconversion (OFU) technique is proposed to solve this problem. In this paper, the novel OFU approach is used to transmit three wireless MIMO signals over a 20 km standard single mode fiber (SMF). The OFU technique exploits one optical source to produce multiple wavelengths by delivering it to a LiNbO3 external optical modulator. The wireless MIMO signals are then modulated by LiNbO3 optical intensity modulators separately using the generated optical carriers from the OFU process. These modulators use the optical single-sideband with carrier (OSSB+C) modulation scheme to optimize the system performance against the fiber dispersion effect. Each wireless MIMO signal is with a 2.4 GHz or 5 GHz carrier frequency, 1 Gb/s data rate, and 16-quadrature amplitude modulation (QAM). The crosstalk between the wireless MIMO signals is highly suppressed, since each wireless MIMO signal is carried on a specific optical wavelength.

  4. Optical Frequency Upconversion Technique for Transmission of Wireless MIMO-Type Signals over Optical Fiber

    PubMed Central

    Shaddad, R. Q.; Mohammad, A. B.; Al-Gailani, S. A.; Al-Hetar, A. M.

    2014-01-01

    The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio-over-fiber (ROF) technique. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as wireless multi-input multi-output (MIMO) signals feeding multiple antennas in the fiber wireless (FiWi) system. A novel optical frequency upconversion (OFU) technique is proposed to solve this problem. In this paper, the novel OFU approach is used to transmit three wireless MIMO signals over a 20 km standard single mode fiber (SMF). The OFU technique exploits one optical source to produce multiple wavelengths by delivering it to a LiNbO3 external optical modulator. The wireless MIMO signals are then modulated by LiNbO3 optical intensity modulators separately using the generated optical carriers from the OFU process. These modulators use the optical single-sideband with carrier (OSSB+C) modulation scheme to optimize the system performance against the fiber dispersion effect. Each wireless MIMO signal is with a 2.4 GHz or 5 GHz carrier frequency, 1 Gb/s data rate, and 16-quadrature amplitude modulation (QAM). The crosstalk between the wireless MIMO signals is highly suppressed, since each wireless MIMO signal is carried on a specific optical wavelength. PMID:24772009

  5. Optical knife-edge technique for nanomechanical displacement detection

    SciTech Connect

    Karabacak, D.; Kouh, T.; Huang, C.C.; Ekinci, K.L.

    2006-05-08

    We describe an optical knife-edge technique for nanomechanical displacement detection. Here, one carefully focuses a laser spot on a moving edge and monitors the reflected power as the edge is displaced sideways. To demonstrate nanomechanical displacement detection using the knife-edge technique, we have measured in-plane resonances of nanometer scale doubly clamped beams. The obtained displacement sensitivity is in the {approx}1 pm/{radical}(Hz) range--in close agreement with a simple analytical model.

  6. Optical strain measuring techniques for high temperature tensile testing

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, John Z.; Hemann, John H.

    1987-01-01

    A number of optical techniques used for the analysis of in-plane displacements or strains are reviewed. The application would be for the high temperature, approximately 1430 C (2600 F), tensile testing of ceramic composites in an oxidizing atmosphere. General descriptions of the various techniques and specifics such as gauge lengths and sensitivities are noted. Also, possible problems with the use of each method in the given application are discussed.

  7. X-ray optics simulation using Gaussian superposition technique.

    PubMed

    Idir, Mourad; Cywiak, Moisés; Morales, Arquímedes; Modi, Mohammed H

    2011-09-26

    We present an efficient method to perform x-ray optics simulation with high or partially coherent x-ray sources using Gaussian superposition technique. In a previous paper, we have demonstrated that full characterization of optical systems, diffractive and geometric, is possible by using the Fresnel Gaussian Shape Invariant (FGSI) previously reported in the literature. The complex amplitude distribution in the object plane is represented by a linear superposition of complex Gaussians wavelets and then propagated through the optical system by means of the referred Gaussian invariant. This allows ray tracing through the optical system and at the same time allows calculating with high precision the complex wave-amplitude distribution at any plane of observation. This technique can be applied in a wide spectral range where the Fresnel diffraction integral applies including visible, x-rays, acoustic waves, etc. We describe the technique and include some computer simulations as illustrative examples for x-ray optical component. We show also that this method can be used to study partial or total coherence illumination problem.

  8. X-ray optics simulation using Gaussian superposition technique

    SciTech Connect

    Idir, M.; Cywiak, M.; Morales, A. and Modi, M.H.

    2011-09-15

    We present an efficient method to perform x-ray optics simulation with high or partially coherent x-ray sources using Gaussian superposition technique. In a previous paper, we have demonstrated that full characterization of optical systems, diffractive and geometric, is possible by using the Fresnel Gaussian Shape Invariant (FGSI) previously reported in the literature. The complex amplitude distribution in the object plane is represented by a linear superposition of complex Gaussians wavelets and then propagated through the optical system by means of the referred Gaussian invariant. This allows ray tracing through the optical system and at the same time allows calculating with high precision the complex wave-amplitude distribution at any plane of observation. This technique can be applied in a wide spectral range where the Fresnel diffraction integral applies including visible, x-rays, acoustic waves, etc. We describe the technique and include some computer simulations as illustrative examples for x-ray optical component. We show also that this method can be used to study partial or total coherence illumination problem.

  9. An Optical Characterization Technique for Parabolic Trough Solar Collectors Using Images of the Absorber Reflection

    NASA Astrophysics Data System (ADS)

    Owkes, Jeanmarie Kathleen

    As the concentrating solar power industry competes to develop a less-expensive parabolic trough collector, assurance is needed that new parabolic trough collectors maintain accurate optical alignment. Previous optical characterization techniques are either too slow, ill-suited for field testing, or do not allow the collector to be tested in realistic orientations. The Observer method presented here enables the rapid optical characterization of parabolic trough collectors in any orientation in the field. The Observer method directly measures the combined optical angular errors in the reflector surface shape and the absorber position, which can be separated into its two components: reflector surface slope and absorber misalignment. The data acquisition requires the placement of photogrammetry targets on and around the collector. Multiple photographs of the absorber and its reflection are taken with a digital camera from different angles with respect to the collector. The images are processed to determine the camera location of each image using photogrammetry bundle analysis. The absorber and its reflection are found in the photographs using image-processing techniques. A Monte Carlo uncertainty model was developed to determine the uncertainty in the Observer measurements. The uncertainty was estimated for a wide array of measurement test scenarios to demonstrate the user's control over the measurement uncertainty. To validate the Observer method, the absorber alignment technique was compared to traditional photogrammetry; the absorber position measured with the two methods compared with a root-mean-square difference of 1.5 mm in the transverse direction and 0.86 mm along the optical axis. The reflector surface slope error measurement was compared to both VSHOT and SOFAST, two well-established optical characterization tools, by measuring a single reflector panel in the laboratory. The VSHOT and SOFAST measurements agreed with the Observer with a root

  10. Optical supervised filtering technique based on Hopfield neural network

    NASA Astrophysics Data System (ADS)

    Bal, Abdullah

    2004-11-01

    Hopfield neural network is commonly preferred for optimization problems. In image segmentation, conventional Hopfield neural networks (HNN) are formulated as a cost-function-minimization problem to perform gray level thresholding on the image histogram or the pixels' gray levels arranged in a one-dimensional array [R. Sammouda, N. Niki, H. Nishitani, Pattern Rec. 30 (1997) 921-927; K.S. Cheng, J.S. Lin, C.W. Mao, IEEE Trans. Med. Imag. 15 (1996) 560-567; C. Chang, P. Chung, Image and Vision comp. 19 (2001) 669-678]. In this paper, a new high speed supervised filtering technique is proposed for image feature extraction and enhancement problems by modifying the conventional HNN. The essential improvement in this technique is to use 2D convolution operation instead of weight-matrix multiplication. Thereby, neural network based a new filtering technique has been obtained that is required just 3 × 3 sized filter mask matrix instead of large size weight coefficient matrix. Optical implementation of the proposed filtering technique is executed easily using the joint transform correlator. The requirement of non-negative data for optical implementation is provided by bias technique to convert the bipolar data to non-negative data. Simulation results of the proposed optical supervised filtering technique are reported for various feature extraction problems such as edge detection, corner detection, horizontal and vertical line extraction, and fingerprint enhancement.

  11. Optical Imaging Techniques for Point-of-care Diagnostics

    PubMed Central

    Zhu, Hongying; Isikman, Serhan O.; Mudanyali, Onur; Greenbaum, Alon; Ozcan, Aydogan

    2012-01-01

    Improving the access to effective and affordable healthcare has long been a global endeavor. In this quest, the development of cost-effective and easy-to-use medical testing equipment that enable rapid and accurate diagnosis is essential to reduce the time and costs associated with healthcare services. To this end, point-of-care (POC) diagnostics plays a crucial role in healthcare delivery in both the developed and developing countries by bringing medical testing to patients, or to sites near patients. As the diagnosis of a wide range of diseases, including various types of cancers and many endemics relies on optical techniques, numerous compact and cost-effective optical imaging platforms have been developed in recent years for use at the POC. Here, we review the state-of-the-art optical imaging techniques that can have significant impact on global health by facilitating effective and affordable POC diagnostics. PMID:23044793

  12. Evaluation of optical reflectance techniques for imaging of alveolar structure

    NASA Astrophysics Data System (ADS)

    Unglert, Carolin I.; Namati, Eman; Warger, William C.; Liu, Linbo; Yoo, Hongki; Kang, DongKyun; Bouma, Brett E.; Tearney, Guillermo J.

    2012-07-01

    Three-dimensional (3-D) visualization of the fine structures within the lung parenchyma could advance our understanding of alveolar physiology and pathophysiology. Current knowledge has been primarily based on histology, but it is a destructive two-dimensional (2-D) technique that is limited by tissue processing artifacts. Micro-CT provides high-resolution three-dimensional (3-D) imaging within a limited sample size, but is not applicable to intact lungs from larger animals or humans. Optical reflectance techniques offer the promise to visualize alveolar regions of the large animal or human lung with sub-cellular resolution in three dimensions. Here, we present the capabilities of three optical reflectance techniques, namely optical frequency domain imaging, spectrally encoded confocal microscopy, and full field optical coherence microscopy, to visualize both gross architecture as well as cellular detail in fixed, phosphate buffered saline-immersed rat lung tissue. Images from all techniques were correlated to each other and then to corresponding histology. Spatial and temporal resolution, imaging depth, and suitability for in vivo probe development were compared to highlight the merits and limitations of each technology for studying respiratory physiology at the alveolar level.

  13. Alignment validation

    SciTech Connect

    ALICE; ATLAS; CMS; LHCb; Golling, Tobias

    2008-09-06

    The four experiments, ALICE, ATLAS, CMS and LHCb are currently under constructionat CERN. They will study the products of proton-proton collisions at the Large Hadron Collider. All experiments are equipped with sophisticated tracking systems, unprecedented in size and complexity. Full exploitation of both the inner detector andthe muon system requires an accurate alignment of all detector elements. Alignmentinformation is deduced from dedicated hardware alignment systems and the reconstruction of charged particles. However, the system is degenerate which means the data is insufficient to constrain all alignment degrees of freedom, so the techniques are prone to converging on wrong geometries. This deficiency necessitates validation and monitoring of the alignment. An exhaustive discussion of means to validate is subject to this document, including examples and plans from all four LHC experiments, as well as other high energy experiments.

  14. An Optical Fiber Displacement Sensor Using RF Interrogation Technique.

    PubMed

    Kim, Hyeon-Ho; Choi, Sang-Jin; Jeon, Keum Soo; Pan, Jae-Kyung

    2016-02-24

    We propose a novel non-contact optical fiber displacement sensor. It uses a radio frequency (RF) interrogation technique which is based on bidirectional modulation of a Mach-Zehnder electro-optical modulator (MZ-EOM). The displacement is measured from the free spectral range (FSR) which is determined by the dip frequencies of the modulated MZ-EOM transfer function. In experiments, the proposed sensor showed a sensitivity of 456 kHz/mm or 1.043 kHz/V in a measurement range of 7 mm. The displacement resolution of the proposed sensor depends on the linewidth and the power of the optical source. Resolution better than 0.05 μm would be achieved if an optical source which has a linewidth narrower than 1.5 nm and a received power larger than -36 dBm is used. Also, the multiplexing characteristic of the proposed sensor was experimentally validated.

  15. An Optical Fiber Displacement Sensor Using RF Interrogation Technique

    PubMed Central

    Kim, Hyeon-Ho; Choi, Sang-Jin; Jeon, Keum Soo; Pan, Jae-Kyung

    2016-01-01

    We propose a novel non-contact optical fiber displacement sensor. It uses a radio frequency (RF) interrogation technique which is based on bidirectional modulation of a Mach-Zehnder electro-optical modulator (MZ-EOM). The displacement is measured from the free spectral range (FSR) which is determined by the dip frequencies of the modulated MZ-EOM transfer function. In experiments, the proposed sensor showed a sensitivity of 456 kHz/mm or 1.043 kHz/V in a measurement range of 7 mm. The displacement resolution of the proposed sensor depends on the linewidth and the power of the optical source. Resolution better than 0.05 μm would be achieved if an optical source which has a linewidth narrower than 1.5 nm and a received power larger than −36 dBm is used. Also, the multiplexing characteristic of the proposed sensor was experimentally validated. PMID:26927098

  16. The Optical Design of a System using a Fresnel Lens that Gathers Light for a Solar Concentrator and that Feeds into Solar Alignment Optics

    NASA Technical Reports Server (NTRS)

    Wilkerson, Gary W.; Huegele, Vinson

    1998-01-01

    The Marshall Space Flight Center (MSFC) has been developing a space deployable, lightweight membrane concentrator to focus solar energy into a solar furnace while remaining aligned to the sun. For an inner surface, this furnace has a cylindrical heat exchanger cavity coaligned to the optical axis; the furnace warms gas to propel the spacecraft. The membrane concentrator is a 1727 mm (68.00 in.) diameter, F/1.7 Fresnel lens. This large membrane is made from polyimide and is 0.076 mm (0.0030 in.) thick; it has the Fresnel grooves cast into it. The solar concentrator system has a super fast paraboloid reflector near the lens focus and immediately adjacent to the cylindrical exchanger cavity. The paraboloid collects the wide bandwidth and some of the solar energy scattered by the Fresnel lens. Finally, the paraboloid feeds the light into the cylinder. The Fresnel lens also possesses a narrow annular zone that focuses a reference beam toward four detectors that keep the optical system aligned to the sun; thus, occurs a refracting lens that focuses two places! The result can be summarized as a composite Fresnel lens for solar concentration and alignment.

  17. Optical design of a system using a Fresnel lens that gathers light for a solar concentrator and that feeds into solar alignment optics

    NASA Astrophysics Data System (ADS)

    Wilkerson, Gary W.; Huegele, Vinson B.

    1998-09-01

    Marshall Space Flight Center has been developing a space deployable, lightweight membrane concentrator to focus energy from the sun into a solar engine while remaining aligned to the sun. For an inner surface, this engine has a cylindrical heat exchanger cavity coaligned to the optical axis; the engine warms gas to propel the spacecraft. The membrane concentrator is a 1727 mm (68.00 in.) diameter, F/1.7 Fresnel lens. This large membrane is made from polyimide and is 0.076 mm (0.0030 in.) thick; it has the Fresnel grooves cast into it. The solar concentrator system has a super fast paraboloid reflector near the lens focus and immediately adjacent to the cylindrical exchanger cavity. The paraboloid collects the wide bandwidth and some of the solar energy scattered by the Fresnel lens. Finally, the paraboloid feeds the light into the cylinder. The Fresnel lens also possesses a narrow annular zone that focuses a reference beam toward four detectors that keep the optical system aligned to the sun; thus, occurs a refracting lens that focuses two places summarized as a composite Fresnel lens for solar concentration and alignment.

  18. Optical Reflection Measurement System Using A Swept Modulation Frequency Technique

    NASA Astrophysics Data System (ADS)

    Braun, David M.; Leyde, Kent W.

    1989-03-01

    A measurement system has been developed capable of mea-suring reflected optical power as low as 0.0025% with a spot size diam-eter of 24 Am. One application for this system is the characterization of small-area photodetectors. The operation of the measurement system is simple, allowing the operator to quickly make multiple reflection measurements, and it does not require a darkroom. The measurement system merges a microscope, for visual alignment and focusing of the laser beam, with a lightwave component analyzer using modulation vec-tor error correction. A measurement comparison between the analyzer-based system and a power-meter-based system showed that each sys-tem can measure reflections as low as 0.0025%. However, the analyzer-based system offers the advantage of identifying the location and magnitude of system reflections. The system operates at a wavelength of 1310 nm.

  19. Optical Alignment and Diffraction Analysis for AIRES: An Airborne Infrared Echelle Spectrometer

    NASA Technical Reports Server (NTRS)

    Haas, Michael R.; Fonda, Mark (Technical Monitor)

    2002-01-01

    The optical design is presented for a long-slit grating spectrometer known as AIRES (Airborne InfraRed Echelle Spectrometer). The instrument employs two gratings in series: a small order sorter and a large steeply blazed echelle. The optical path includes four pupil and four field stops, including two narrow slits. A detailed diffraction analysis is performed using GLAD by Applied Optics Research to evaluate critical trade-offs between optical throughput, spectral resolution, and system weight and volume. The effects of slit width, slit length, oversizing the second slit relative to the first, on- vs off-axis throughput, and clipping at the pupil stops and other optical elements are discussed.

  20. Alignment of optical system components using an ADM beam through a null assembly

    NASA Technical Reports Server (NTRS)

    Hayden, Joseph E. (Inventor); Olczak, Eugene G. (Inventor)

    2010-01-01

    A system for testing an optical surface includes a rangefinder configured to emit a light beam and a null assembly located between the rangefinder and the optical surface. The null assembly is configured to receive and to reflect the emitted light beam toward the optical surface. The light beam reflected from the null assembly is further reflected back from the optical surface toward the null assembly as a return light beam. The rangefinder is configured to measure a distance to the optical surface using the return light beam.

  1. Passively aligned multichannel fiber-pigtailing of planar integrated optical waveguides

    NASA Astrophysics Data System (ADS)

    Kremmel, Johannes; Lamprecht, Tobias; Crameri, Nino; Michler, Markus

    2017-02-01

    A silicon device to simplify the coupling of multiple single-mode fibers to embedded single-mode waveguides has been developed. The silicon device features alignment structures that enable a passive alignment of fibers to integrated waveguides. For passive alignment, precisely machined V-grooves on a silicon device are used and the planar lightwave circuit board features high-precision structures acting as a mechanical stop. The approach has been tested for up to eight fiber-to-waveguide connections. The alignment approach, the design, and the fabrication of the silicon device as well as the assembly process are presented. The characterization of the fiber-to-waveguide link reveals total coupling losses of (0.45±0.20 dB) per coupling interface, which is significantly lower than the values reported in earlier works. Subsequent climate tests reveal that the coupling losses remain stable during thermal cycling but increases significantly during an 85°C/85 Rh-test. All applied fabrication and bonding steps have been performed using standard MOEMS fabrication and packaging processes.

  2. Transmission line resonance technique for eccentric core optical fibers

    NASA Astrophysics Data System (ADS)

    Georgantzos, E.; Boucouvalas, A. C.

    2016-12-01

    In several cases optical fibers in telecommunications have cores of non circular geometry. Fibre optic deformations appear in optical fibres for many reasons. Optical fibre core ellipticity for example where the fibre optic core is not perfectly circular due to fibre optic manufacturing tolerances, is measured and often is a problem. Optical fibre core eccentricity, where the fibre core is not on the axis of the fibre, but it is offset by a small length. This is another issue and very important for ensuring performance low loss splices and connector losses. Both of ellipticity and eccentricity are specified in accordance to international standards for fibre optic manufacturing telecommunications grade fibres. The present paper studies ellipticity and core eccentricity specifically and presents a new method for analysing their effect. We present an extension of the transmission line technique as a means of studying such fibers and deriving necessary parameters. Conformal mapping on the other hand is a simple mathematical tool by which we can generate sets of orthogonal two-dimensional coordinate systems. Shortly a conformal map of Cartesian two-dimensional space is defined by any analytical function W(z) where z, w, are: z = x + jy, W = θ + j φ The function deriving by the conformal mapping transformation h(θ ,φ )=| ∂w/∂z | = 1/|∂z/∂w|, can be used in order to define ∇A → and ∇×A → where A → is the magnetic or electric field in the derived orthogonal coordinate system. Useful conformal maps for fiber optics applications should have the property that the equation θ(x, y) = constant, is forming closed curves in a Cartesian two-dimensional space (x,y). If θ(x, y) = constant represents a set of co-eccentric circles, we obtain the normal case of conventional fibers with circular cores. If θ(x, y) = constant represents a set of eclipses, we are have the formation of elliptic core optical fibers. If θ(x, y) = constant represents a set of

  3. Production of a Self-Aligned Scaffold, Free of Exogenous Material, from Dermal Fibroblasts Using the Self-Assembly Technique

    PubMed Central

    Bolduc, Stéphane

    2016-01-01

    Many pathologies of skin, especially ageing and cancer, involve modifications in the matrix alignment. Such tissue reorganization could have impact on cell behaviour and/or more global biological processes. Tissue engineering provides accurate study model by mimicking the skin and it allows the construction of versatile tridimensional models using human cells. It also avoids the use of animals, which gave sometimes nontranslatable results. Among the various techniques existing, the self-assembly method allows production of a near native skin, free of exogenous material. After cultivating human dermal fibroblasts in the presence of ascorbate during two weeks, a reseeding of these cells takes place after elevation of the resulting stroma on a permeable ring and culture pursued for another two weeks. This protocol induces a clear realignment of matrix fibres and cells parallel to the horizon. The thickness of this stretched reconstructed tissue is reduced compared to the stroma produced by the standard technique. Cell count is also reduced. In conclusion, a new, easy, and inexpensive method to produce aligned tissue free of exogenous material could be used for fundamental research applications in dermatology. PMID:27051415

  4. Precise identification of <1 0 0> directions on Si{0 0 1} wafer using a novel self-aligning pre-etched technique

    NASA Astrophysics Data System (ADS)

    Singh, S. S.; Veerla, S.; Sharma, V.; Pandey, A. K.; Pal, P.

    2016-02-01

    Micromirrors with a tilt angle of 45° are widely used in optical switching and interconnect applications which require 90° out of plane reflection. Silicon wet bulk micromachining based on surfactant added TMAH is usually employed to fabricate 45° slanted walls at the < 1 0 0> direction on Si≤ft\\{0 0 1\\right\\} wafers. These slanted walls are used as 45° micromirrors. However, the appearance of a precise 45° ≤ft\\{0 1 1\\right\\} wall is subject to the accurate identification of the < 1 0 0> direction. In this paper, we present a simple technique based on pre-etched patterns for the identification of < 1 0 0> directions on the Si≤ft\\{0 0 1\\right\\} surface. The proposed pre-etched pattern self-aligns itself at the < 1 0 0> direction while becoming misaligned at other directions. The < 1 0 0> direction is determined by a simple visual inspection of pre-etched patterns and does not need any kind of measurement. To test the accuracy of the proposed method, we fabricated a 32 mm long rectangular opening with its sides aligned along the < 1 0 0> direction, which is determined using the proposed technique. Due to the finite etch rate of the ≤ft\\{1 1 0\\right\\} plane, undercutting occurred, which was measured at 12 different locations along the longer edge of the rectangular strip. The mean of these undercutting lengths, measured perpendicular to the mask edge, is found to be 13.41 μm with a sub-micron standard deviation of 0.38 μm. This level of uniform undercutting indicates that our method of identifying the < 1 0 0> direction is precise and accurate. The developed method will be extremely useful in fabricating arrays of 45° micromirrors.

  5. Electro-optic techniques in electron beam diagnostics

    SciTech Connect

    van Tilborg, Jeroen; Toth, Csaba; Matlis, Nicholas; Plateau, Guillaume; Leemans, Wim

    2011-06-17

    Electron accelerators such as laser wakefield accelerators, linear accelerators driving free electron lasers, or femto-sliced synchrotrons, are capable of producing femtosecond-long electron bunches. Single-shot characterization of the temporal charge profile is crucial for operation, optimization, and application of such accelerators. A variety of electro-optic sampling (EOS) techniques exists for the temporal analysis. In EOS, the field profile from the electron bunch (or the field profile from its coherent radiation) will be transferred onto a laser pulse co-propagating through an electro-optic crystal. This paper will address the most common EOS schemes and will list their advantages and limitations. Strong points that all techniques share are the ultra-short time resolution (tens of femtoseconds) and the single-shot capabilities. Besides introducing the theory behind EOS, data from various research groups is presented for each technique.

  6. Alignment analyses of a galvanometer-based scanner in free-space Fourier domain optical coherence tomography.

    PubMed

    Yuan, Qun; Zhu, Dan; Gao, Zhishan

    2015-11-10

    Free-space Fourier domain optical coherence tomography is adopted for biomedical imaging with ultrahigh resolution, in which the setup consists of an interferometer and a spectrometer. Two-dimensional lateral sampling in the sample arm of the interferometer is achieved by using a galvanometer-based scanner. Optical path difference (OPD) drift in the full scan field of view is observed in the assembly process of the scanner. A galvo mirror mount offset with respect to the rotation axis is demonstrated as the derivation of this OPD drift by both geometric analyses and model building. Then, an iterative assembly process of the scanner is proposed with the OPD drift taken as the alignment criteria.

  7. Detection and alignment of XY skew for dual-polarization optical quadrature amplitude transmitter using reconfigurable interference

    NASA Astrophysics Data System (ADS)

    Yue, Yang; Zhang, Bo; Wang, Qiang; Lofland, Rob; O'Neil, Jason; Anderson, Jon

    2016-02-01

    DP-QAM is one of the feasible paths towards 100Gbps, 400Gbps and 1Tbps optical communications systems. For DPQAM transmitter, the time mismatch between the XY tributary channels is known as the XY skew. Large uncompensated XY skew can significantly degrade the system performance. Sometimes, time-interleaved return-to-zero DP signal is preferred with lower nonlinear polarization scattering induced penalty. In this work, XY skew detection and alignment of dual-polarization optical quadrature amplitude transmitter using reconfigurable interference is experimentally demonstrated with >23-dB dynamic range. ~1.5-dB power change is achieved for 1-ps XY skew. Fast detecting scheme for arbitrary skew measurement is also experimentally verified. The scheme is compatible with different modulation formats, data sequences, and waveforms.

  8. Hot-embossing replication of self-centering optical fiber alignment structures prototyped by deep proton writing

    NASA Astrophysics Data System (ADS)

    Ebraert, Evert; Wissmann, Markus; Guttmann, Markus; Kolew, Alexander; Worgull, Matthias; Barié, Nicole; Schneider, Marc; Hofmann, Andreas; Beri, Stefano; Watté, Jan; Thienpont, Hugo; Van Erps, Jürgen

    2016-07-01

    This paper presents the hot-embossing replication of self-centering fiber alignment structures for high-precision, single-mode optical fiber connectors. To this end, a metal mold insert was fabricated by electroforming a polymer prototype patterned by means of deep proton writing (DPW). To achieve through-hole structures, we developed a postembossing process step to remove the residual layer inherently present in hot-embossed structures. The geometrical characteristics of the hot-embossed replicas are compared, before and after removal of the residual layer, with the DPW prototypes. Initial measurements on the optical performance of the replicas are performed. The successful replication of these components paves the way toward low-cost mass replication of DPW-fabricated prototypes in a variety of high-tech plastics.

  9. Innovative, Inexpensive Etching Technique Developed for Polymer Electro- Optical Structures

    NASA Technical Reports Server (NTRS)

    Nguyen, Hung D.

    1999-01-01

    Electro-optic, polymer-based integrated optic devices for high-speed communication and computing applications offer potentially significant advantages over conventional inorganic electro-optic crystals. One key area of integrated optical technology--primary processing and fabrication--may particularly benefit from the use of polymer materials. However, as efforts concentrate on the miniaturization of electro-integrated circuit pattern geometries, the ability to etch fine features and smoothly sloped sidewalls is essential to make polymers useful for electro-integrated circuit applications. There are many existing processes available to etch polymer materials, but they all yield nearly vertical sidewalls. Vertical sidewalls are too difficult to reliably cover with a metal layer, and incomplete metalization degrades microwave performance, particularly at high frequency. However, obtaining a very sloped sidewall greatly improves the deposition of metal on the sidewall, leading to low-loss characteristics, which are essential to integrating these devices in highspeed electro-optic modulators. The NASA Lewis Research Center has developed in-house an inexpensive etching technique that uses a photolithography method followed by a simple, wet chemical etching process to etch through polymer layers. In addition to being simpler and inexpensive, this process can be used to fabricate smoothly sloped sidewalls by using a commercial none rodible mask: Spin-On-Glass. A commercial transparent material, Spin-On-Glass, uses processes and equipment similar to that for photoresist techniques.

  10. Quantitative optical techniques for dense sprays investigation: A survey

    NASA Astrophysics Data System (ADS)

    Coghe, A.; Cossali, G. E.

    2012-01-01

    The experimental study of dense sprays by optical techniques poses many challenges and no methods have proven to be completely reliable when accurate quantitative data are required, for example to validate breakup models and CFD simulations. The present survey is aimed to a critical analysis of optical techniques capable to provide quantitative and reliable data in dense sprays and to point out the conditions necessary to safely obtain such measurements. A single parameter, the optical depth, is proposed to quantify the concept of dense spray and to indicate when multiple scattering becomes predominant and could make the experimental results questionable. Many available optical techniques are divided into two categories: the "classical" ones, like PDA, LDV, PIV, etc., that work well in dilute sprays but show many limitations in dense sprays, and the "emerging" ones more suitable for dense sprays. Among the last ones, those considered more promising are discussed in detail. A number of significant applications are also presented and discussed to better clarify the nature of such complex problem and the feasibility of the new proposed approaches.

  11. Study of optical techniques for the Ames unitary wind tunnels. Part 1: Schlieren

    NASA Technical Reports Server (NTRS)

    Lee, George

    1992-01-01

    Alignment procedures and conceptual designs for the rapid alignment of the Ames Unitary Wind Tunnel schlieren systems were devised. The schlieren systems can be aligned by translating the light source, the mirrors, and the knife edge equal distances. One design for rapid alignment consists of a manual pin locking scheme. The other is a motorized electronic position scheme. A study of two optical concepts which can be used with the schlieren system was made. These are the 'point diffraction interferometers' and the 'focus schlieren'. Effects of vibrations were studied.

  12. The use of optical imaging techniques in the gastrointestinal tract

    PubMed Central

    Beg, Sabina; Wilson, Ana; Ragunath, Krish

    2016-01-01

    With significant advances in the management of gastrointestinal disease there has been a move from diagnosing advanced pathology, to detecting early lesions that are potentially amenable to curative endoscopic treatment. This has required an improvement in diagnostics, with a focus on identifying and characterising subtle mucosal changes. There is great interest in the use of optical technologies to predict histology and enable the formulation of a real-time in vivo diagnosis, a so-called ‘optical biopsy’. The aim of this review is to explore the evidence for the use of the current commercially available imaging techniques in the gastrointestinal tract. PMID:27429735

  13. The formation of vertically aligned biaxial tungsten nanorods using a novel shadowing growth technique

    NASA Astrophysics Data System (ADS)

    Krishnan, R.; Parker, T.; Lee, S.; Lu, T.-M.

    2009-11-01

    Biaxially textured tungsten nanorods (A15 crystal structure) have been grown by oblique angle DC magnetron sputtering using a novel rotation mode called 'two-step rotation'. In this mode, the substrate is given a fast rotation through 180° at 90 rpm and this is followed by a rest period of 30 s. These nanorods are vertically aligned and have a [100] texture normal to the substrate along with preferential in-plane texture as shown by x-ray pole figure analysis. In contrast, the tungsten nanorods obtained without substrate rotation are slanted at an angle of ~45° and have a [100] texture tilted 16° with respect to the substrate normal. The flux is incident from two diametrically opposite points on the sample at an oblique angle, averaging out the growth into vertical columns that retain the in-plane texture. Scanning electron microscopy shows that the tungsten nanorods have a mixture of {211} and {421} crystal habits; these planes are both minimum surface energy planes for a cubic A15 crystal structure.

  14. Fast and accurate registration techniques for affine and nonrigid alignment of MR brain images.

    PubMed

    Liu, Jia-Xiu; Chen, Yong-Sheng; Chen, Li-Fen

    2010-01-01

    Registration of magnetic resonance brain images is a geometric operation that determines point-wise correspondences between two brains. It remains a difficult task due to the highly convoluted structure of the brain. This paper presents novel methods, Brain Image Registration Tools (BIRT), that can rapidly and accurately register brain images by utilizing the brain structure information estimated from image derivatives. Source and target image spaces are related by affine transformation and non-rigid deformation. The deformation field is modeled by a set of Wendland's radial basis functions hierarchically deployed near the salient brain structures. In general, nonlinear optimization is heavily engaged in the parameter estimation for affine/non-rigid transformation and good initial estimates are thus essential to registration performance. In this work, the affine registration is initialized by a rigid transformation, which can robustly estimate the orientation and position differences of brain images. The parameters of the affine/non-rigid transformation are then hierarchically estimated in a coarse-to-fine manner by maximizing an image similarity measure, the correlation ratio, between the involved images. T1-weighted brain magnetic resonance images were utilized for performance evaluation. Our experimental results using four 3-D image sets demonstrated that BIRT can efficiently align images with high accuracy compared to several other algorithms, and thus is adequate to the applications which apply registration process intensively. Moreover, a voxel-based morphometric study quantitatively indicated that accurate registration can improve both the sensitivity and specificity of the statistical inference results.

  15. Low-temperature growth of aligned ZnO nanorods: effect of annealing gases on the structural and optical properties.

    PubMed

    Umar, Ahmad; Hahn, Yoon-Bong; Al-Hajry, A; Abaker, M

    2014-06-01

    Aligned ZnO nanorods were grown on ZnO/Si substrate via simple aqueous solution process at low-temperature of - 65 degrees C by using zinc nitrate and hexamethylenetetramine (HMTA). The detailed morphological and structural properties measured by FESEM, XRD, EDS and TEM confirmed that the as-grown nanorods are vertically aligned, well-crystalline possessing wurtzite hexagonal phase and grown along the [0001] direction. The room-temperature photoluminescence spectrum of the grown nanorods exhibited a strong and broad green emission and small ultraviolet emission. The as-prepared ZnO nanorods were post-annealed in nitrogen (N2) and oxygen (O2) environments and further characterized in terms of their morphological, structural and optical properties. After annealing the nanorods exhibit well-crystallinity and wurtzite hexagonal phase. Moreover, by annealing the PL spectra show the enhancement in the UV emission and suppression in the green emission. The presented results demonstrate that simply by post-annealing process, the optical properties of ZnO nanostructures can be controlled.

  16. Detection and alignment of dual-polarization optical quadrature amplitude transmitter IQ and XY skews using reconfigurable interference.

    PubMed

    Yue, Yang; Zhang, Bo; Wang, Qiang; Lofland, Rob; O'Neil, Jason; Anderson, Jon

    2016-03-21

    Dual-polarization quadrature amplitude modulation (DP-QAM) is one of the feasible paths towards 100-Gb/s, 400-Gb/s and 1-Tb/s optical fiber communications systems. For DP-QAM transmitter, the time mismatch between the in-phase and quadrature (IQ) or x-polarized and y-polarized (XY) tributary channels is known as the IQ or XY skew. Large uncompensated IQ or XY skew can significantly degrade the optical fiber communications system performance. Sometimes, time-interleaved return-to-zero (RZ) DP signal is preferred with lower nonlinear polarization scattering induced penalty. In this work, detection and alignment of DP-QAM transmitter IQ and XY skews using reconfigurable interference is experimentally demonstrated. For IQ skew detection, a total dynamic range of 26.4 dB is achieved with ~1-dB power change for 0.5-ps skew from well alignment. For XY skew detection, it shows 23.2-dB dynamic range, and ~1.5-dB power change is achieved for 1-ps XY skew. Fast detection algorithm for arbitrary skew is also proposed and experimentally verified. The scheme is compatible with different modulation formats, flexible data sequences, and variable waveforms.

  17. Implementation of Accelerated Beam-Specific Matched-Filter-Based Optical Alignment

    SciTech Connect

    Awwal, A S; Rice, K L; Taha, T M

    2009-01-29

    Accurate automated alignment of laser beams in the National Ignition Facility (NIF) is essential for achieving extreme temperature and pressure required for inertial confinement fusion. The alignment achieved by the integrated control systems relies on algorithms processing video images to determine the position of the laser beam images in real-time. Alignment images that exhibit wide variations in beam quality require a matched-filter algorithm for position detection. One challenge in designing a matched-filter based algorithm is to construct a filter template that is resilient to variations in imaging conditions while guaranteeing accurate position determination. A second challenge is to process the image as fast as possible. This paper describes the development of a new analytical template that captures key recurring features present in the beam image to accurately estimate the beam position under good image quality conditions. Depending on the features present in a particular beam, the analytical template allows us to create a highly tailored template containing only those selected features. The second objective is achieved by exploiting the parallelism inherent in the algorithm to accelerate processing using parallel hardware that provides significant performance improvement over conventional processors. In particular, a Xilinx Virtex II Pro FPGA hardware implementation processing 32 templates provided a speed increase of about 253 times over an optimized software implementation running on a 2.0 GHz AMD Opteron core.

  18. Multi-object Feature Detection and Error Correction for NIF Automatic Optical Alignment

    SciTech Connect

    Awwal, A S

    2006-07-17

    Fiducials imprinted on laser beams are used to perform video image based alignment of the beams in the National Ignition Facility (NIF) of Lawrence Livermore National Laboratory. In any laser beam alignment operation, a beam needs to be aligned to a reference location. Generally, the beam and reference fiducials are composed of separate beams, as a result only a single feature of each beam needs to be identified for determining the position of the beam or reference. However, it is possible to have the same beam image contain both the beam and reference fiducials. In such instances, it is essential to separately identify these features. In the absence of wavefront correction or when image quality is poor, the features of such beams may get distorted making it difficult to distinguish between different fiducials. Error checking and correction mechanism must be implemented to avoid misidentification of one type of feature as the other. This work presents the algorithm for multi-object detection and error correction implemented for such a beam line image in the NIF facility. Additionally, we show how when the original algorithm fails a secondary algorithm takes over and provides required location outputs.

  19. Development of a lidar technique for profiling optical turbulence

    NASA Astrophysics Data System (ADS)

    Gimmestad, Gary; Roberts, David; Stewart, John; Wood, Jack

    2012-10-01

    Many techniques have been proposed for active optical remote sensing of the strength of atmospheric refractive turbulence. The early techniques, based on degradation of laser beams by turbulence, were susceptible to artifacts. In 1999, we began investigating a new idea, based on differential image motion (DIM), which is inherently immune to artifacts. The new lidar technique can be seen as a combination of two astronomical instruments: a laser guide star transmitter/receiver and a DIM monitor. The technique was successfully demonstrated on a horizontal path, with a hard-target analog of a lidar, and then a true lidar was developed. Several investigations were carried out first, including an analysis to predict the system's performance; new hard-target field measurements in the vertical direction; development of a robust inversion technique; and wave optics simulations. A brassboard lidar was then constructed and operated in the field, along with instruments to acquire truth data. The tests revealed many problems and pitfalls that were all solvable with engineering changes, and the results served to verify the new lidar technique for profiling turbulence. The results also enabled accurate performance predictions for future versions of the lidar. A transportable turbulence lidar system is currently being developed to support field tests of high-energy lasers.

  20. Hermetic fiber optic-to-metal connection technique

    DOEpatents

    Kramer, Daniel P.

    1992-09-01

    A glass-to-glass hermetic sealing technique is disclosed which can be used to splice lengths of glass fibers together. A solid glass preform is inserted into the cavity of a metal component which is then heated to melt the glass. An end of an optical fiber is then advanced into the molten glass and the entire structure cooled to solidify the glass in sealing engagement with the optical fiber end and the metal cavity. The surface of the re-solidified glass may be machined for mating engagement with another component to make a spliced fiber optic connection. The resultant structure has a helium leak rate of less than 1.times.10.sup.-8 cm.sup.3 /sec.

  1. Advanced optical techniques for monitoring dosimetric parameters in photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Li, Buhong; Qiu, Zhihai; Huang, Zheng

    2012-12-01

    Photodynamic therapy (PDT) is based on the generation of highly reactive singlet oxygen through interactions of photosensitizer, light and molecular oxygen. PDT has become a clinically approved, minimally invasive therapeutic modality for a wide variety of malignant and nonmalignant diseases. The main dosimetric parameters for predicting the PDT efficacy include the delivered light dose, the quantification and photobleaching of the administrated photosensitizer, the tissue oxygen concentration, the amount of singlet oxygen generation and the resulting biological responses. This review article presents the emerging optical techniques that in use or under development for monitoring dosimetric parameters during PDT treatment. Moreover, the main challenges in developing real-time and noninvasive optical techniques for monitoring dosimetric parameters in PDT will be described.

  2. Optical fiber technique for in-reactor mechanical properties measurement

    SciTech Connect

    Schley, R. S.; Hurley, D. H.; Hua, Z. A.

    2013-01-25

    In-reactor measurement of material properties is required for a better understanding of radiation effects on materials. We present an optical fiber based technique for measuring changes in elastic properties which involves exciting and measuring flexural vibrations in a thin cantilever beam. By exciting the beam and measuring the resonant frequency, changes in the modulus of elasticity can be monitored. The technique is demonstrated by monitoring the elastic property changes of a beam fabricated from copper, as the copper undergoes recrystallization at elevated temperature.

  3. Optical Fiber Technique for In-Reactor Mechanical Properties Measurement

    SciTech Connect

    Robert S. Schley; Zilong Hua; David H. Hurley; Heng Ban

    2012-07-01

    In-reactor measurement of material properties is required for a better understanding of radiation effects on materials. We present an optical fiber based technique for measuring changes in elastic properties which involves exciting and measuring flexural vibrations in a thin cantilever beam. By exciting the beam and measuring the natural frequency, changes in the modulus of elasticity can be monitored. The technique is demonstrated by monitoring the elastic property changes of a beam fabricated from copper, as the copper undergoes recrystallization at elevated temperature.

  4. Optical fiber technique for in-reactor mechanical properties measurement

    NASA Astrophysics Data System (ADS)

    Schley, R. S.; Hurley, D. H.; Hua, Z. A.

    2013-01-01

    In-reactor measurement of material properties is required for a better understanding of radiation effects on materials. We present an optical fiber based technique for measuring changes in elastic properties which involves exciting and measuring flexural vibrations in a thin cantilever beam. By exciting the beam and measuring the resonant frequency, changes in the modulus of elasticity can be monitored. The technique is demonstrated by monitoring the elastic property changes of a beam fabricated from copper, as the copper undergoes recrystallization at elevated temperature.

  5. A patient alignment solution for lung SBRT setups based on a deformable registration technique

    SciTech Connect

    Lu Bo; Mittauer, Kathryn; Li, Jonathan; Samant, Sanjiv; Dagan, Roi; Okunieff, Paul; Kahler, Darren; Liu, Chihray

    2012-12-15

    Purpose: In this work, the authors propose a novel registration strategy for translation-only correction scenarios of lung stereotactic body radiation therapy setups, which can achieve optimal dose coverage for tumors as well as preserve the consistency of registrations with minimal human interference. Methods: The proposed solution (centroid-to-centroidor CTC solution) uses the average four-dimensional CT (A4DCT) as the reference CT. The cone-beam CT (CBCT) is deformed to acquire a new centroid for the internal target volume (ITV) on the CBCT. The registration is then accomplished by simply aligning the centroids of the ITVs between the A4DCT and the CBCT. Sixty-seven cases using 64 patients (each case is associated with separate isocenters) have been investigated with the CTC method and compared with the conventional gray-value (G) mode and bone (B) mode registration methods. Dosimetric effects among the tree methods were demonstrated by 18 selected cases. The uncertainty of the CTC method has also been studied. Results: The registration results demonstrate the superiority of the CTC method over the other two methods. The differences in the D99 and D95 ITV dose coverage between the CTC method and the original plan is small (within 5%) for all of the selected cases except for one for which the tumor presented significant growth during the period between the CT scan and the treatment. Meanwhile, the dose coverage differences between the original plan and the registration results using either the B or G method are significant, as tumor positions varied dramatically, relative to the rib cage, from their positions on the original CT. The largest differences between the D99 and D95 dose coverage of the ITV using the B or G method versus the original plan are as high as 50%. The D20 differences between any of the methods versus the original plan are all less than 2%. Conclusions: The CTC method can generate optimal dose coverage to tumors with much better consistency

  6. A New Technique to Map the Lymphatic Distribution and Alignment of the Penis.

    PubMed

    Long, Liu Yan; Qiang, Pan Fu; Ling, Tao; Wei, Zhang Yan; Long, Zhang Yu; Shan, Meng; Rong, Li Shi; Li, Li Hong

    2015-08-01

    of the penis and folded at the abdominal wall to the outside, and finally merged into the inguinal lymph nodes. The changes in distribution, number and diameter of the lymphatic vessels in the penis were observed by MRI. MIP and MIMICS reconstructions directly revealed the anatomical features of penile lymphatic vessels such as spatial distribution, overall alignment, and the relations to adjacent structures, drainage and reflux. The study will provide the anatomical basis for penile surgery, penile lymphatic reflux disorders caused by trauma or lymphatic vessels obstruction, and lymph node metastasis in penile cancer.

  7. Optical Microscopy Techniques to Inspect for Metallic Whiskers

    NASA Technical Reports Server (NTRS)

    Brusse, Jay A.

    2006-01-01

    Metal surface finishes of tin, zinc and cadmium are often applied to electronic components, mechanical hardware and other structures. These finishes sometimes unpredictably may form metal whiskers over periods that can take from hours to months or even many years. The metal whiskers are crystalline structures commonly having uniform cross sectional area along their entire length. Typical whisker dimensions are nominally on the order of only a few microns (um) across while their lengths can extend from a few microns to several millimeters. Metal whiskers pose a reliability hazard to electronic systems primarily as an electrical shorting hazard. The extremely narrow dimensions of metal whiskers can make observation with optical techniques very challenging. The videos herein were compiled to demonstrate the complexities associated with optical microscope inspection of electronic and mechanical components and assemblies for the presence or absence of metal whiskers. The importance of magnification, light source and angle of illumination play critical roles in being able to detect metal whiskers when present. Furthermore, it is demonstrated how improper techniques can easily obscure detection. It is hoped that these videos will improve the probability of detecting metal whiskers with optical inspection techniques.

  8. Nonlinear Magneto-optical Rotation via Alignment-to-Orientation Conversion

    SciTech Connect

    Budker, D.; Kimball, D.F.; Rochester, S.M.; Yashchuk, V.V.

    2000-03-10

    Nonlinear magneto-optical rotation (NMOR) is investigated at highlight powers where the rotation is significantly modified by AC Stark shifts. These shifts are shown to change the overall sign of rotation for closed F-->F+1 transitions as light power is increased. The effect is demonstrated by measurements in rubidium and density matrix calculations. The results are important for applications of nonlinear optical rotation such as sensitive magnetometry.

  9. Wavefront alignment research of segmented mirror synthetic aperture optical (SAO) system

    NASA Astrophysics Data System (ADS)

    Deng, Jian; An, Xiaoqiang; Tian, Hao

    2010-05-01

    Wavefront control technology and imaging experiment are introduced for a segmented mirror SAO system with deformable sub-mirrors. This system is a RC style with 300mm aperture, 4.5 F#, +/-0.4°FOV, 0.45~0.75μm wave band, and diffraction-limit design MTF. The primary mirror is composed by three sub-mirrors, with parabolic shape, and each deformable sub-mirror has 19 actuators to control and keep the surface shape, and 5 actuators to align sub-mirrors location in 5 degree of freedom. Interferometer is used to feed back and control exit wavefront error, and base on measurement and finite element analysis, location and quanitity of actuators are optimized, making the surface shape and misadjustment errors interact and compensate each other, and the synthetic system exit pupil wavefront error is controlled. The integrated exit pupil wavefront errors are gotten by ZYGO interferometer, and central FOV is 0.077λRMS, and edge FOV is 0.093λRMS. At the end, an imaging experiment is executed, and good results are obtained, which proves, the deformable sub-mirrors have the ability to meliorate alignment and the latter can retroact the former, and this relationship iterate make system exit pupil wavefront error convergence and improve segmented mirror SAO system imaging ability.

  10. Enhanced optical output power of blue light-emitting diodes with quasi-aligned gold nanoparticles

    PubMed Central

    2014-01-01

    The output power of the light from GaN-based light-emitting diodes (LEDs) was enhanced by fabricating gold (Au) nanoparticles on the surface of p-GaN. Quasi-aligned Au nanoparticle arrays were prepared by depositing Au thin film on an aligned suspended carbon nanotube thin film surface and then putting the Au-CNT system on the surface of p-GaN and thermally annealing the sample. The size and position of the Au nanoparticles were confined by the carbon nanotube framework, and no other additional residual Au was distributed on the surface of the p-GaN substrate. The output power of the light from the LEDs with Au nanoparticles was enhanced by 55.3% for an injected current of 100 mA with the electrical property unchanged compared with the conventional planar LEDs. The enhancement may originate from the surface plasmon effect and scattering effect of the Au nanoparticles. PMID:24393473

  11. Liquid sound speeds at pressure from the optical analyzer technique

    SciTech Connect

    Fritz, J.N.; Morris, C.E.; Hixson, R.S.; McQueen, R.G.

    1993-08-01

    The optical analyzer technique has proved to be a useful means of obtaining wave velocities at high pressures. Stepped wedges of the investigated material emit shock, and later, rarefaction waves into a transparent analyzer covering the material. The time interval between shock and rarefaction plotted versus wedge thickness gives a linear plot whose intercept fixes the target/driver thickness ratio for exact wave overtake, and thus gives a relation between the shock velocity and overtaking wave velocity at pressure. The slope of this line is intimately related to the wave velocity at pressure of the analyzer in front of the wedge. This aspect of the technique has not yet been exploited. We present the appropriate analysis, some data on bromoform (one of the analyzers used), and discuss some possible applications of this technique.

  12. Application of optical correlation techniques to particle imaging velocimetry

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.; Edwards, Robert V.

    1988-01-01

    Pulsed laser sheet velocimetry yields nonintrusive measurements of velocity vectors across an extended 2-dimensional region of the flow field. The application of optical correlation techniques to the analysis of multiple exposure laser light sheet photographs can reduce and/or simplify the data reduction time and hardware. Here, Matched Spatial Filters (MSF) are used in a pattern recognition system. Usually MSFs are used to identify the assembly line parts. In this application, the MSFs are used to identify the iso-velocity vector contours in the flow. The patterns to be recognized are the recorded particle images in a pulsed laser light sheet photograph. Measurement of the direction of the partical image displacements between exposures yields the velocity vector. The particle image exposure sequence is designed such that the velocity vector direction is determined unambiguously. A global analysis technique is used in comparison to the more common particle tracking algorithms and Young's fringe analysis technique.

  13. New optical tomographic & topographic techniques for biomedical applications

    NASA Astrophysics Data System (ADS)

    Buytaert, Jan

    The mammalian middle ear contains the eardrum and the three auditory ossicles, and forms an impedance match between sound in air and pressure waves in the fluid of the inner ear. Without this intermediate system, with its unsurpassed efficiency and dynamic range, we would be practically deaf. Physics-based modeling of this extremely complex mechanical system is necessary to help our basic understanding of the functioning of hearing. Highly realistic models will make it possible to predict the outcome of surgical interventions and to optimize design of ossicle prostheses and active middle ear implants. To obtain such models and with realistic output, basic input data is still missing. In this dissertation I developed and used two new optical techniques to obtain two essential sets of data: accurate three-dimensional morphology of the middle ear structures, and elasticity parameters of the eardrum. The first technique is a new method for optical tomography of macroscopic biomedical objects, which makes it possible to measure the three-dimensional geometry of the middle ear ossicles and soft tissues which are connecting and suspending them. I made a new and high-resolution version of this orthogonal-plane fluorescence optical sectioning method, to obtain micrometer resolution in macroscopic specimens. The result is thus a complete 3-D model of the middle (and inner) ear of gerbil in unprecedented quality. On top of high-resolution morphological models of the middle ear structures, I applied the technique in other fields of research as well. The second device works according to a new optical profilometry technique which allows to measure shape and deformations of the eardrum and other membranes or objects. The approach is called projection moire profilometry, and creates moire interference fringes which contain the height information. I developed a setup which uses liquid crystal panels for grid projection and optical demodulation. Hence no moving parts are present and

  14. Nonlinear optical Spectroscopy of Polyimide Surface for homeotropic liquid crystal alignment

    NASA Astrophysics Data System (ADS)

    Oh-E, Masahito; Kim, Doseok

    2005-03-01

    Surface--specific sum--frequency vibrational spectroscopy and second--harmonic generation were used to study the structures of polyimide (PI) surfaces for homeotropic liquid crystal (LC) alignment and the molecular orientation of LC adsobates on these surfaces. The imide ring was perpendicular to the surface with one of CO bonds protruding out of the surface and the other pointing into the bulk rather than flat on the surface. The ester CO bond in the side chain was sticking out of the surface with a tilt angle of about 40--55^o from the surface normal, indicating that the rigid side chain core was, more or less, along the surface normal. The part of alkyl chain on the top of the side chain followed the orientation of the side chain core and protruded out of the surface with some gauche defects. The cyano biphenyl LC molecules were adsorbed on the PI preferentially with the terminal cyano group facing the PI surface.

  15. Mapping molecular conformation and orientation of polyimide surfaces for homeotropicliquid crystal alignment by nonlinear optical spectroscopy

    NASA Astrophysics Data System (ADS)

    Oh-E, Masahito; Yokoyama, Hiroshi; Kim, Doseok

    2004-05-01

    Surface-specific sum-frequency vibrational spectroscopy and second-harmonic generation were used to study the structures of polyimide (PI) surfaces for homeotropic liquid crystal (LC) alignment and the molecular orientation of LC adsobates on these surfaces. The imide ring was perpendicular to the surface with one of CO bonds protruding out of the surface and the other pointing into the bulk rather than flat on the surface. The ester CO bond in the side chain was sticking out of the surface with a tilt angle of about 45° 55° from the surface normal, indicating that the rigid side chain core was, more or less, along the surface normal. The part of alkyl chain on the top of the side chain followed the orientation of the side chain core and protruded out of the surface with some gauche defects. The cyano biphenyl LC molecules were adsorbed on the PI preferentially with the terminal cyano group facing the PI surface.

  16. Experimental Estimation of CLASP Spatial and Spectral Resolutions: Results of the Instrument's Optical Alignment

    NASA Technical Reports Server (NTRS)

    Giono, G.; Katsukawa, Y.; Ishikawa, R.; Narukage, N.; Bando, T.; Kano, R.; Suematsu, Y.; Winebarger, A.; Kobayashi, K.; Auchere, F.

    2015-01-01

    The Chromospheric Lyman-Alpha SpectroPolarimeter is a sounding rocket experiment design to measure for the first time the polarization signal of the Lyman-Alpha line (121.6nm), emitted in the solar upper-chromosphere and transition region. This instrument aims to detect the Hanle effect's signature hidden in the Ly-alpha polarization, as a tool to probe the chromospheric magnetic field. Hence, an unprecedented polarization accuracy is needed ((is) less than 10 (exp -3). Nevertheless, spatial and spectral resolutions are also crucial to observe chhromospheric feature such as spicules, and to have precise measurement of the Ly-alpha line core and wings. Hence, this poster will present how the telescope and the spectrograph were separately aligned, and their combined spatial and spectral resolutions.

  17. Development of Optical Diagnostic Techniques for Microgravity Materials Processing

    NASA Technical Reports Server (NTRS)

    Cha, Soyoung Stephen

    1999-01-01

    Materials processing including crystal growth, either under a gravity environment on ground or a microgravity environment in space, involves complicated phenomena of fluid motions in gas or liquid phases as well as interaction of various species. To obtain important physical insight, it is very necessary to provide gross-field optical diagnostics for monitoring various physical properties. Materials processing inhibits easy access by ordinary instruments and thus characterizing gross-field physical properties is very challenging. Typical properties of importance can be fluid velocity, temperature, and species concentration for fluids, and surface topology and defects for solids. Observing surface grow rate during crystal growth is also important. Material microstructures, i.e., integrity of crystal structures, is strongly influenced by the existence of thermally-induced flow as well as local nucleation of particles during solidification, which may act in many detrimental ways. In both ground-based and microgravity experiments, the nature of product property changes resulting from three-dimensional fluid or particle motions need be characterized. Gross-field diagnostics is thus required to identify their effects on product defects and process deficiencies. The quantitative visualization techniques can also be used for validation of numerical modeling. For optical nonintrusive gross-field diagnostic techniques, two approaches were developed as summer projects. One optical approach allows us to provide information of species concentration and temperature for monitoring in real time. The other approach, that is, the concept which is formulated for detection of surface topography measurement can provide unprecedented spatial resolution during crystal growth.

  18. Fiber optic diagnostic techniques applied to electrical discharge machining sparks

    NASA Astrophysics Data System (ADS)

    Pillans, B. W.; Evensen, M. H.; Taylor, H. F.; Eubank, P. T.; Ma, Lianxi

    2002-02-01

    Plasma sparks from an electrical discharge machining (EDM) process were observed using fiber optics positioned in the dielectric oil. Measurement techniques were developed to observe the spark in the extremely noisy environment. Optical data were used along with current pulse wave forms from the EDM machine to study the temporal characteristics of the spark in both the pulse time and the pause time. During the pause time, extinction of the sparks was longer than previously thought—perhaps due to the remaining infrared radiation after the collapse of the spark. Further, an optical pattern was identified that indicated in advance when an arc was being formed instead of a spark. Spectral data of the plasma spark was obtained by using a scanning grating spectrometer in conjunction with crosscorrelation to maximize the signal-to-noise ratio. Average spark temperatures from the spectral data were found to be significantly higher than those previously predicted from energy balances. The results showed a shift in the optical spectra to longer wavelengths during the spark, showing that the spark temperature decreased with time.

  19. Anti-drift and auto-alignment mechanism for an astigmatic atomic force microscope system based on a digital versatile disk optical head.

    PubMed

    Hwu, E-T; Illers, H; Wang, W-M; Hwang, I-S; Jusko, L; Danzebrink, H-U

    2012-01-01

    In this work, an anti-drift and auto-alignment mechanism is applied to an astigmatic detection system (ADS)-based atomic force microscope (AFM) for drift compensation and cantilever alignment. The optical path of the ADS adopts a commercial digital versatile disc (DVD) optical head using the astigmatic focus error signal. The ADS-based astigmatic AFM is lightweight, compact size, low priced, and easy to use. Furthermore, the optical head is capable of measuring sub-atomic displacements of high-frequency AFM probes with a sub-micron laser spot (~570 nm, FWHM) and a high-working bandwidth (80 MHz). Nevertheless, conventional DVD optical heads suffer from signal drift problems. In a previous setup, signal drifts of even thousands of nanometers had been measured. With the anti-drift and auto-alignment mechanism, the signal drift is compensated by actuating a voice coil motor of the DVD optical head. A nearly zero signal drift was achieved. Additional benefits of this mechanism are automatic cantilever alignment and simplified design.

  20. Bilateral apical vertebral derotation technique by vertebral column manipulation compared with vertebral coplanar alignment technique in the correction of lenke type 1 idiopathic scoliosis

    PubMed Central

    2013-01-01

    Background Widely used rod rotation and translation techniques for idiopathic scoliosis (IS) are effective in correcting spinal coronal deformity. Bilateral apical vertebral derotation technique by vertebral column manipulation (VCM) and vertebral coplanar alignment (VCA) technique are two strategies for three-dimensional (3D) correction for IS. The purpose of this study is to compare the post-surgical results and technical features of the bilateral apical vertebral derotation technique by VCM against the VCA technique in patients with Lenke type 1 IS. Methods Forty-eight patients with Lenke type 1 IS were enrolled in the present prospective clinical assay. They were divided into groups A (bilateral apical vertebral derotation technique by VCM, n=24) and B (VCA technique, n=24). Radiographic parameters measured before and after surgery included the Cobb angle, thoracic kyphosis, and apical vertebral rotation. Scoliosis Research Society (SRS)-22 scores were evaluated during the final follow-up. The differences in the demographics, surgical details, and radiographic measurements between the two groups were determined using a T test. The Mann–Whitney U test was used to evaluate the differences in the SRS-22 scores. A value of P<0.05 was considered statistically significant. Results In the coronal plane, a significant difference was found in the correction rate of the major curve (group A: 84.8%, group B: 78.4%; P=0.045) and in the Cincinnati Correction Index between two groups (group A: 2.21, group B: 1.98; P=0.047). In the sagittal plane, no difference was found in the postoperative thoracic kyphosis between the two groups (P=0.328). In the transverse plane, no difference was found between the two groups in the correction rates of the rotation angle sagittal (P=0.298), rib hump (P=0.934), apical vertebral body-to-rib ratio (P=0.988), or apical rib spread difference (P=0.184). Patients underwent follow up for an average of 21.9 and 22.2 months in groups A and B

  1. Simple technique for integrating compact silicon devices within optical fibers.

    PubMed

    Micco, A; Ricciardi, A; Quero, G; Crescitelli, A; Bock, W J; Cusano, A

    2014-02-15

    In this work, we present a simple fabrication process enabling the integration of a subwavelength amorphous silicon layer inside optical fibers by means of the arc discharge technique. To assess our method, we have fabricated a compact in-line Fabry-Perot interferometer consisting of a thin (<1  μm) a-Si:H layer completely embedded within a standard single-mode optical fiber. The device exhibits low loss (1.3 dB) and high interference fringe visibility (~80%) both in reflection and transmission, due to the high refractive index contrast between silica and a-Si:H. A high linear temperature sensitivity up to 106  pm/°C is demonstrated in the range 120°C-400°C. The proposed interferometer is attractive for point monitoring applications as well as for ultrahigh-temperature sensing in harsh environments.

  2. Feasibility and optical performance of one axis three positions sun-tracking polar-axis aligned CPCs for photovoltaic applications

    SciTech Connect

    Tang, Runsheng; Yu, Yamei

    2010-09-15

    A new design concept, called one axis three positions sun-tracking polar-axis aligned CPCs (3P-CPCs, in short), was proposed and theoretically studied in this work for photovoltaic applications. The proposed trough-like CPC is oriented in the polar-axis direction, and the aperture is daily adjusted eastward, southward, and westward in the morning, noon and afternoon, respectively, by rotating the CPC trough, to ensure efficient collection of beam radiation nearly all day. To investigate the optical performance of such CPCs, an analytical mathematical procedure is developed to estimate daily and annual solar gain captured by such CPCs based on extraterrestrial radiation and monthly horizontal radiation. Results show that the acceptance half-angle of 3P-CPCs is a unique parameter to determine their optical performance according to extraterrestrial radiation, and the annual solar gain stays constant if the acceptance half-angle, {theta}{sub a}, is less than one third of {omega}{sub 0,min}, the sunset hour angle in the winter solstice, otherwise decreases with the increase of {theta}{sub a}. For 3P-CPCs used in China, the annual solar gain, depending on the climatic conditions in site, decreased with the acceptance half-angle, but such decrease was slow for the case of {theta}{sub a}{<=}{omega}{sub 0,min}/3, indicating that the acceptance half-angle should be less than one third of {omega}{sub 0,min} for maximizing annual energy collection. Compared to fixed east-west aligned CPCs (EW-CPCs) with a yearly optimal acceptance half-angle, the fixed south-facing polar-axis aligned CPCs (1P-CPCs) with the same acceptance half-angle as the EW-CPCs annually collected about 65-74% of that EW-CPCs did, whereas 3P-CPCs annually collected 1.26-1.45 times of that EW-CPCs collected, indicating that 3P-CPCs were more efficient for concentrating solar radiation onto their coupling solar cells. (author)

  3. Optical multiple access techniques for on-board routing

    NASA Technical Reports Server (NTRS)

    Mendez, Antonio J.; Park, Eugene; Gagliardi, Robert M.

    1992-01-01

    The purpose of this research contract was to design and analyze an optical multiple access system, based on Code Division Multiple Access (CDMA) techniques, for on board routing applications on a future communication satellite. The optical multiple access system was to effect the functions of a circuit switch under the control of an autonomous network controller and to serve eight (8) concurrent users at a point to point (port to port) data rate of 180 Mb/s. (At the start of this program, the bit error rate requirement (BER) was undefined, so it was treated as a design variable during the contract effort.) CDMA was selected over other multiple access techniques because it lends itself to bursty, asynchronous, concurrent communication and potentially can be implemented with off the shelf, reliable optical transceivers compatible with long term unattended operations. Temporal, temporal/spatial hybrids and single pulse per row (SPR, sometimes termed 'sonar matrices') matrix types of CDMA designs were considered. The design, analysis, and trade offs required by the statement of work selected a temporal/spatial CDMA scheme which has SPR properties as the preferred solution. This selected design can be implemented for feasibility demonstration with off the shelf components (which are identified in the bill of materials of the contract Final Report). The photonic network architecture of the selected design is based on M(8,4,4) matrix codes. The network requires eight multimode laser transmitters with laser pulses of 0.93 ns operating at 180 Mb/s and 9-13 dBm peak power, and 8 PIN diode receivers with sensitivity of -27 dBm for the 0.93 ns pulses. The wavelength is not critical, but 830 nm technology readily meets the requirements. The passive optical components of the photonic network are all multimode and off the shelf. Bit error rate (BER) computations, based on both electronic noise and intercode crosstalk, predict a raw BER of (10 exp -3) when all eight users are

  4. Measuring the In-Process Figure, Final Prescription, and System Alignment of Large Optics and Segmented Mirrors Using Lidar Metrology

    NASA Technical Reports Server (NTRS)

    Ohl, Raymond; Slotwinski, Anthony; Eegholm, Bente; Saif, Babak

    2011-01-01

    The fabrication of large optics is traditionally a slow process, and fabrication capability is often limited by measurement capability. W hile techniques exist to measure mirror figure with nanometer precis ion, measurements of large-mirror prescription are typically limited to submillimeter accuracy. Using a lidar instrument enables one to measure the optical surface rough figure and prescription in virtuall y all phases of fabrication without moving the mirror from its polis hing setup. This technology improves the uncertainty of mirror presc ription measurement to the micron-regime.

  5. Optical modulation techniques for analog signal processing and CMOS compatible electro-optic modulation

    NASA Astrophysics Data System (ADS)

    Gill, Douglas M.; Rasras, Mahmoud; Tu, Kun-Yii; Chen, Young-Kai; White, Alice E.; Patel, Sanjay S.; Carothers, Daniel; Pomerene, Andrew; Kamocsai, Robert; Beattie, James; Kopa, Anthony; Apsel, Alyssa; Beals, Mark; Mitchel, Jurgen; Liu, Jifeng; Kimerling, Lionel C.

    2008-02-01

    Integrating electronic and photonic functions onto a single silicon-based chip using techniques compatible with mass-production CMOS electronics will enable new design paradigms for existing system architectures and open new opportunities for electro-optic applications with the potential to dramatically change the management, cost, footprint, weight, and power consumption of today's communication systems. While broadband analog system applications represent a smaller volume market than that for digital data transmission, there are significant deployments of analog electro-optic systems for commercial and military applications. Broadband linear modulation is a critical building block in optical analog signal processing and also could have significant applications in digital communication systems. Recently, broadband electro-optic modulators on a silicon platform have been demonstrated based on the plasma dispersion effect. The use of the plasma dispersion effect within a CMOS compatible waveguide creates new challenges and opportunities for analog signal processing since the index and propagation loss change within the waveguide during modulation. We will review the current status of silicon-based electrooptic modulators and also linearization techniques for optical modulation.

  6. Modelling of side-wall angle for optical proximity correction for self-aligned double patterning

    NASA Astrophysics Data System (ADS)

    Moulis, Sylvain; Farys, Vincent; Belledent, Jérôme; Foucher, Johann

    2012-03-01

    The pursuit of even smaller transistors has pushed some technological innovations in the field of lithography. In order to continue following the path of Moore's law, several solutions were proposed: EUV, e-beam and double patterning lithography. As EUV and e-beam lithography are still not ready for mass production for 20nm and 14nm nodes, double patterning lithography will play an important role for these nodes. In this work, we had focused on Self- Aligned Double-Patterning processes which consist in depositing a spacer material on each side of a mandrel exposed during a first lithography stepmaking the pitch to be divided by two after transfer into the substrate, the cutting of unwanted patterns being addressed through a second lithography exposure. In the specific case where spacers are deposited directly on the flanks of the resist, it is crucial to control its profiles as it could induce final CD errors or even spacer collapse. In this work, we will first study with a simple model the influence of the resist profile on the post-etch spacer CD. Then we will show that the placement of Sub-Resolution Assist Features (SRAF) can influence the resist profile and finally, we will see how much control of the spacer and inter-spacer CD we can achieve by tuning SRAF placement.

  7. Development of optical systems. [holographic technique for monitoring crystal growth

    NASA Technical Reports Server (NTRS)

    Vikram, Chandra S.

    1995-01-01

    Several key aspects of multi-color holography and laser speckle technique to study holographic reconstructions are considered in the report. Holographic fringe contrast in two-color holography in the presence of a fluid cell in the object beam is discussed in detail. A specific example of triglycine sulfate crystal growth is also considered. A breadboard design using fiber optics and diode lasers for three-color holography for fluid experiments is presented. A possible role of multi-color holography in various new applications is summarized. Finally, the use of a a laser speckle technique is demonstrated for the study of holographic reconstructions. The demonstration is performed using a Spacelab 3 hologram.

  8. Noninvasive detection of cardiovascular pulsations by optical Doppler techniques

    NASA Astrophysics Data System (ADS)

    Hong, HyunDae; Fox, Martin D.

    1997-10-01

    A system has been developed based on the measurement of skin surface vibration that can be used to detect the underlying vascular wall motion of superficial arteries and the chest wall. Data obtained from tissue phantoms suggested that the detected signals were related to intravascular pressure, an important clinical and physiological parameter. Unlike the conventional optical Doppler techniques that have been used to measure blood perfusion in skin layers and blood flow within superficial arteries, the present system was optimized to pick up skin vibrations. An optical interferometer with a 633-nm He:Ne laser was utilized to detect micrometer displacements of the skin surface. Motion velocity profiles of the skin surface near each superficial artery and auscultation points on a chest for the two heart valve sounds exhibited distinctive profiles. The theoretical and experimental results demonstrated that the system detected the velocity of skin movement, which is related to the time derivative of the pressure. The system also reduces the loading effect on the pulsation signals and heart sounds produced by the conventional piezoelectric vibration sensors. The system's sensitivity, which could be optimized further, was 366.2 micrometers /s for the present research. Overall, optical cardiovascular vibrometry has the potential to become a simple noninvasive approach to cardiovascular screening.

  9. Three-dimensional imaging technique using optical diffraction

    NASA Astrophysics Data System (ADS)

    Tan, Sheng; Hart, Douglas P.

    2002-02-01

    This paper presents a novel fast and simple technique to measure three-dimensional (3D) objects. An integrated 3D camera is built, which features a motorized off-axis rotating aperture. A regular spot pattern projection adds texture onto smooth 3D objects. When rotating, the off-axis aperture translates depth information into blurred image diameter. The displacement of each spot between two arbitrary aperture positions reveals depth. A pseudo- correlation algorithm based on optical diffraction is proposed to measure spot displacement fast and accurately. When subtracting two consecutive images of a roughly Gaussian-shaped displaced spot, the normalized subtraction intensity peak height is directly proportional to the spot displacement. The peak height to displacement calibration curve is specifically defined by optical parameters of the imaging system. Proper combination of off-axis aperture location and magnification ratio determines the size of the measurement range. Experiment observations show that the calibration curve is highly smooth and sensitive to the spot displacement at sub-pixel level. Real-time processing is possible with only order of image size arithmetic operations. The proposed technique holds potential for various industrial machine vision applications.

  10. Application of optical spectroscopic techniques for disease diagnosis

    NASA Astrophysics Data System (ADS)

    Saha, Anushree

    Optical spectroscopy, a truly non-invasive tool for remote diagnostics, is capable of providing valuable information on the structure and function of molecules. However, most spectroscopic techniques suffer from drawbacks, which limit their application. As a part of my dissertation work, I have developed theoretical and experimental methods to address the above mentioned issues. I have successfully applied these methods for monitoring the physical, chemical and biochemical parameters of biomolecules involved in some specific life threatening diseases like lead poisoning and age-related macular degeneration (AMD). I presented optical studies of melanosomes, which are one of the vital organelles in the human eye, also known to be responsible for a disease called age-related macular degeneration (AMD), a condition of advanced degeneration which causes progressive blindness. I used Raman spectroscopy, to first chemically identify the composition of melanosome, and then monitor the changes in its functional and chemical behavior due to long term exposure to visible light. The above study, apart from explaining the role of melanosomes in AMD, also sets the threshold power for lasers used in surgeries and other clinical applications. In the second part of my dissertation, a battery of spectroscopic techniques was successfully applied to explore the different binding sites of lead ions with the most abundant carrier protein molecule in our circulatory system, human serum albumin. I applied optical spectroscopic tools for ultrasensitive detection of heavy metal ions in solution which can also be used for lead detection at a very early stage of lead poisoning. Apart from this, I used Raman microspectroscopy to study the chemical alteration occurring inside a prostate cancer cell as a result of a treatment with a low concentrated aqueous extract of a prospective drug, Nerium Oleander. The experimental methods used in this study has tremendous potential for clinical

  11. Room-temperature near-infrared silicon carbide nanocrystalline emitters based on optically aligned spin defects

    SciTech Connect

    Muzha, A.; Fuchs, F.; Simin, D.; Astakhov, G. V.; Tarakina, N. V.; Trupke, M.; Soltamov, V. A.; Mokhov, E. N.; Baranov, P. G.; Dyakonov, V.; and others

    2014-12-15

    Bulk silicon carbide (SiC) is a very promising material system for bio-applications and quantum sensing. However, its optical activity lies beyond the near infrared spectral window for in-vivo imaging and fiber communications due to a large forbidden energy gap. Here, we report the fabrication of SiC nanocrystals and isolation of different nanocrystal fractions ranged from 600 nm down to 60 nm in size. The structural analysis reveals further fragmentation of the smallest nanocrystals into ca. 10-nm-size clusters of high crystalline quality, separated by amorphization areas. We use neutron irradiation to create silicon vacancies, demonstrating near infrared photoluminescence. Finally, we detect room-temperature spin resonances of these silicon vacancies hosted in SiC nanocrystals. This opens intriguing perspectives to use them not only as in-vivo luminescent markers but also as magnetic field and temperature sensors, allowing for monitoring various physical, chemical, and biological processes.

  12. Fringe biasing: A variance reduction technique for optically thick meshes

    SciTech Connect

    Smedley-Stevenson, R. P.

    2013-07-01

    Fringe biasing is a stratified sampling scheme applicable to Monte Carlo thermal radiation transport codes. The thermal emission source in optically thick cells is partitioned into separate contributions from the cell interiors (where the likelihood of the particles escaping the cells is virtually zero) and the 'fringe' regions close to the cell boundaries. Thermal emission in the cell interiors can now be modelled with fewer particles, the remaining particles being concentrated in the fringes so that they are more likely to contribute to the energy exchange between cells. Unlike other techniques for improving the efficiency in optically thick regions (such as random walk and discrete diffusion treatments), fringe biasing has the benefit of simplicity, as the associated changes are restricted to the sourcing routines with the particle tracking routines being unaffected. This paper presents an analysis of the potential for variance reduction achieved from employing the fringe biasing technique. The aim of this analysis is to guide the implementation of this technique in Monte Carlo thermal radiation codes, specifically in order to aid the choice of the fringe width and the proportion of particles allocated to the fringe (which are interrelated) in multi-dimensional simulations, and to confirm that the significant levels of variance reduction achieved in simulations can be understood by studying the behaviour for simple test cases. The variance reduction properties are studied for a single cell in a slab geometry purely absorbing medium, investigating the accuracy of the scalar flux and current tallies on one of the interfaces with the surrounding medium. (authors)

  13. Measurement of wavefront and Wigner distribution function for optics alignment and full beam characterization of FELs

    NASA Astrophysics Data System (ADS)

    Mey, Tobias; Schäfer, Bernd; Mann, Klaus; Keitel, Barbara; Kreis, Svea; Kuhlmann, Marion; Plönjes, Elke; Tiedtke, Kai

    2013-05-01

    Free-electron lasers deliver EUV and soft x-ray pulses with the highest brilliance available and high spatial coherence. Users of such facilities have high demands on the coherence properties of the beam, for instance when working with coherent di ractive imaging (CDI). Experimentally, we are recovering the phase distribition with an EUV Hartmann wavefront sensor. This allows for online adjustment of focusing optics such as ellipsoidal or Kirkpatrick-Baez mirrors minimizing the aberrations in the focused beam. To gain highly resolved spatial coherence information, we have performed a caustic scan at beamline BL2 of the free-electron laser FLASH using the ellipsoidal focusing mirror and a movable EUV sensitized CCD detector. This measurement allows for retrieving the Wigner distribution function, being the two-dimensional Fourier transform of the mutual intensity of the beam. Computing the reconstruction on a four-dimensional grid, this yields the entire Wigner distribution which describes the beam propagation completely. Hence, we are able to provide comprehensive information about spatial coherence properties of the FLASH beam including the global degree of coherence. Additionally, we derive the beam propagation parameters such as Rayleigh length, waist diameter and M2.

  14. Thermocapillary Technique for Shaping and Fabricating Optical Ribbon Waveguides

    NASA Astrophysics Data System (ADS)

    Fiedler, Kevin; Troian, Sandra

    The demand for ever increasing bandwidth and higher speed communication has ushered the next generation optoelectronic integrated circuits which directly incorporate polymer optical waveguide devices. Polymer melts are very versatile materials which have been successfully cast into planar single- and multimode waveguides using techniques such as embossing, photolithography and direct laser writing. In this talk, we describe a novel thermocapillary patterning method for fabricating waveguides in which the free surface of an ultrathin molten polymer film is exposed to a spatially inhomogeneous temperature field via thermal conduction from a nearby cooled mask pattern held in close proximity. The ensuring surface temperature distribution is purposely designed to pool liquid selectively into ribbon shapes suitable for optical waveguiding, but with rounded and not rectangular cross sectional areas due to capillary forces. The solidified waveguide patterns which result from this non-contact one step procedure exhibit ultrasmooth interfaces suitable for demanding optoelectronic applications. To complement these studies, we have also conducted finite element simulations for quantifying the influence of non-rectangular cross-sectional shapes on mode propagation and losses. Kf gratefully acknowledges support from a NASA Space Technology Research Fellowship.

  15. Optical transmission testing based on asynchronous sampling techniques

    NASA Astrophysics Data System (ADS)

    Mrozek, T.; Perlicki, K.; Wilczewski, G.

    2016-09-01

    This paper presents a method of analysis of images obtained with the Asynchronous Delay Tap Sampling technique, which is used for simultaneous monitoring of a number of phenomena in the physical layer of an optical network. This method allows visualization of results in a form of an optical signal's waveform (characteristics depicting phase portraits). Depending on a specific phenomenon being observed (i.e.: chromatic dispersion, polarization mode dispersion and ASE noise), the shape of the waveform changes. Herein presented original waveforms were acquired utilizing the OptSim 4.0 simulation package. After specific simulation testing, the obtained numerical data was transformed into an image form, that was further subjected to the analysis using authors' custom algorithms. These algorithms utilize various pixel operations and creation of reports each image might be characterized with. Each individual report shows the number of black pixels being present in the specific image segment. Afterwards, generated reports are compared with each other, across the original-impaired relationship. The differential report is created which consists of a "binary key" that shows the increase in the number of pixels in each particular segment. The ultimate aim of this work is to find the correlation between the generated binary keys and the analyzed common phenomenon being observed, allowing identification of the type of interference occurring. In the further course of the work it is evitable to determine their respective values. The presented work delivers the first objective - the ability to recognize interference.

  16. Cloud cover estimation optical package: New facility, algorithms and techniques

    NASA Astrophysics Data System (ADS)

    Krinitskiy, Mikhail

    2017-02-01

    Short- and long-wave radiation is an important component of surface heat budget over sea and land. For estimating them accurate observations of the cloud cover are needed. While massively observed visually, for building accurate parameterizations cloud cover needs also to be quantified using precise instrumental measurements. Major disadvantages of the most of existing cloud-cameras are associated with their complicated design and inaccuracy of post-processing algorithms which typically result in the uncertainties of 20% to 30% in the camera-based estimates of cloud cover. The accuracy of these types of algorithm in terms of true scoring compared to human-observed values is typically less than 10%. We developed new generation package for cloud cover estimating, which provides much more accurate results and also allows for measuring additional characteristics. New algorithm, namely SAIL GrIx, based on routine approach, also developed for this package. It uses the synthetic controlling index ("grayness rate index") which allows to suppress the background sunburn effect. This makes it possible to increase the reliability of the detection of the optically thin clouds. The accuracy of this algorithm in terms of true scoring became 30%. One more approach, namely SAIL GrIx ML, we have used to increase the cloud cover estimating accuracy is the algorithm that uses machine learning technique along with some other signal processing techniques. Sun disk condition appears to be a strong feature in this kind of models. Artificial Neural Networks type of model demonstrates the best quality. This model accuracy in terms of true scoring increases up to 95,5%. Application of a new algorithm lets us to modify the design of the optical sensing package and to avoid the use of the solar trackers. This made the design of the cloud camera much more compact. New cloud-camera has already been tested in several missions across Atlantic and Indian oceans on board of IORAS research vessels.

  17. Design of Optical Systems with Extended Depth of Field: An Educational Approach to Wavefront Coding Techniques

    ERIC Educational Resources Information Center

    Ferran, C.; Bosch, S.; Carnicer, A.

    2012-01-01

    A practical activity designed to introduce wavefront coding techniques as a method to extend the depth of field in optical systems is presented. The activity is suitable for advanced undergraduate students since it combines different topics in optical engineering such as optical system design, aberration theory, Fourier optics, and digital image…

  18. Synthesis of "cactus" top-decorated aligned carbon nanotubes and their third-order nonlinear optical properties.

    PubMed

    Li, P H; Qu, Y L; Xu, X J; Zhu, Y W; Yu, T; Chin, K C; Mi, J; Gao, X Y; Lim, C T; Shen, Z X; Wee, A T S; Ji, W; Sow, C H

    2006-04-01

    We report a new morphology of "cactus" top-decorated aligned carbon nanotubes grown by the PECVD method using pure C2H2 gas. Unlike most previous reports, no additional carrier gas is used for pretreatment. Carbon nanotubes can still grow and maintain the tubular structure underneath the "cactus" tops. It is proposed that the H atoms produced by the dissociation of C2H2 activate the catalyst nanoparticles. Scanning electron microscopy (SEM) shows that the top "cactus" morphology is composed of a large quantity of small nanosheets. Transmission electron microscopy (TEM) reveals the amorphous carbon nature of these "cactus" structures. The formation of these "cactus" structures is possibly due to covalent absorption and reconstruction of carbon atoms on the broken graphite layers of nanotubes produced by the strong ion bombardment under plasma. The third-order optical nonlinearities and nonlinear dynamics are also investigated. The third-order nonlinear susceptibility magnitude /chi(3)/ is found to be 2.2 x 10(-11) esu, and the relaxation process takes place in about 1.8 ps.

  19. A novel twisted nematic alignment and its effects on the electro-optical dynamics of nanoscale liquid crystalline films

    NASA Astrophysics Data System (ADS)

    Rauzan, Brittany; Lee, Lay Min; Nuzzo, Ralph

    2015-03-01

    Vibrational spectroscopic studies of a surface induced, twisted alignment of the nematic liquid crystal, 4-n-pentyl-4'-cyanobiphenyl (5CB) and its temperature-dependent electro-optical (EO) dynamics were studied near the crystalline-nematic and nematic-isotropic transition temperatures, and at a median temperature in the nematic phase. A 50 nm thick film of 5CB was confined in nanocavities defined by the dimensions of a gold interdigitated electrode array patterned on a unidirectionally polished ZnSe substrate. The film was assembled between two polished substrates bearing extended nanometer-scaled grooves that are oriented orthogonally to one another. The results show that with this anchoring scheme, the molecular director of the LC film undergoes a ninety-degree twist. Step-scan time resolved spectroscopy (TRS) measurements were made to determine the rate constants for the temperature-dependent EO dynamics of both the electric field-induced orientation and thermal relaxation processes of the LC film. The work rationalizes the impacts of organizational anisotropy and illustrates how it can be exploited as a design principle to effectively influence the electric field-induced dynamics of LC systems.

  20. Tumor functional and molecular imaging utilizing ultrasound and ultrasound-mediated optical techniques.

    PubMed

    Yuan, Baohong; Rychak, Joshua

    2013-02-01

    Tumor functional and molecular imaging has significantly contributed to cancer preclinical research and clinical applications. Among typical imaging modalities, ultrasonic and optical techniques are two commonly used methods; both share several common features such as cost efficiency, absence of ionizing radiation, relatively inexpensive contrast agents, and comparable maximum-imaging depth. Ultrasonic and optical techniques are also complementary in imaging resolution, molecular sensitivity, and imaging space (vascular and extravascular). The marriage between ultrasonic and optical techniques takes advantages of both techniques. This review introduces tumor functional and molecular imaging using microbubble-based ultrasound and ultrasound-mediated optical imaging techniques.

  1. Response Surface Methods for Spatially-Resolved Optical Measurement Techniques

    NASA Technical Reports Server (NTRS)

    Danehy, P. M.; Dorrington, A. A.; Cutler, A. D.; DeLoach, R.

    2003-01-01

    Response surface methods (or methodology), RSM, have been applied to improve data quality for two vastly different spatial ly-re solved optical measurement techniques. In the first application, modern design of experiments (MDOE) methods, including RSM, are employed to map the temperature field in a direct-connect supersonic combustion test facility at NASA Langley Research Center. The laser-based measurement technique known as coherent anti-Stokes Raman spectroscopy (CARS) is used to measure temperature at various locations in the combustor. RSM is then used to develop temperature maps of the flow. Even though the temperature fluctuations at a single point in the flowfield have a standard deviation on the order of 300 K, RSM provides analytic fits to the data having 95% confidence interval half width uncertainties in the fit as low as +/-30 K. Methods of optimizing future CARS experiments are explored. The second application of RSM is to quantify the shape of a 5-meter diameter, ultra-light, inflatable space antenna at NASA Langley Research Center.

  2. Fine-Tunable Absorption of Uniformly Aligned Polyurea Thin Films for Optical Filters Using Sequentially Self-Limited Molecular Layer Deposition.

    PubMed

    Park, Yi-Seul; Choi, Sung-Eun; Kim, Hyein; Lee, Jin Seok

    2016-05-11

    Development of methods enabling the preparation of uniformly aligned polymer thin films at the molecular level is a prerequisite for realizing their optoelectronic characteristics as innovative materials; however, these methods often involve a compromise between scalability and accuracy. In this study, we have grown uniformly aligned polyurea thin films on a SiO2 substrate using molecular layer deposition (MLD) based on sequential and self-limiting surface reactions. By integrating plane-polarized Fourier-transform infrared, Raman spectroscopic tools, and density functional theory calculations, we demonstrated the uniform alignment of polyurea MLD films. Furthermore, the selective-wavelength absorption characteristics of thickness-controlled MLD films were investigated by integrating optical measurements and finite-difference time-domain simulations of reflection spectra, resulting from their thickness-dependent fine resonance with photons, which could be used as color filters in optoelectronics.

  3. Optical characterization of hydrogenated silicon thin films using interference technique

    NASA Astrophysics Data System (ADS)

    Globus, Tatiana; Ganguly, Gautam; Roca i Cabarrocas, Pere

    2000-08-01

    This work introduces an application of an "interference spectroscopy technique" (IST) for determination of absorption coefficient and refractive index spectra of amorphous silicon (a-Si:H) and related thin film materials. The technique is based on computer analysis of measurements of optical transmission and specular reflection (T & R) of thin films (including the films on substrates) over a wide range of the incident photon energies (0.5-2.8 eV) using carefully controlled spectrometer conditions. IST is used to investigate the absorption spectrum in the sub-gap energy range (0.8-1.6 eV) of intrinsic and phosphorous-doped a-Si:H, "polymorphous-Si:H," and microcrystalline silicon films. The enhanced sensitivity of the technique over conventional analysis of T & R data results from utilization of interference to obtain absorption coefficient values at the maxima of transmission. The factors limiting the accuracy of the calculated absorption coefficient are discussed in detail. Measurement on films of thickness ranging from 0.1 to 5 μm identifies that the sub-gap absorption in these films arises from the bulk rather than the surface. A set of samples prepared under widely different conditions that appear to have overlapping (α=20 cm-1) sub-gap absorption spectra measured using photo-thermal deflection spectroscopy (PDS), reveal significant differences (α=10 to 100 cm-1) using IST. Changes (factor of 2) in sub-gap absorption spectra due to light soaking are also clearly observable using IST.

  4. Pulse-to-pulse alignment based on interference fringes and the second-order temporal coherence function of optical frequency combs for distance measurement.

    PubMed

    Zhu, Jigui; Cui, Pengfei; Guo, Yin; Yang, Linghui; Lin, Jiarui

    2015-05-18

    A pulse-to-pulse alignment method based on interference fringes and the second-order temporal coherence function of optical frequency combs is proposed for absolute distance measurement. The second-order temporal coherence function of the pulse train emitted from optical frequency combs is studied. A numerical model of the function is developed with an assumption of Gaussian pulse and has good agreement with experimental measurements taken by an ordinary Michelson interferometer. The experimental results show an improvement of standard deviation of peak finding results from 27.3 nm to 8.5 nm by the method in ordinary laboratory conditions. The absolute distance measurement with the pulse-to-pulse alignment method is also proposed and experimentally proved.

  5. Application of Fiber-Optical Techniques in the Access Transmission and Backbone Transport of Mobile Networks

    NASA Astrophysics Data System (ADS)

    Hilt, Attila; Pozsonyi, László

    2012-09-01

    Fixed access networks widely employ fiber-optical techniques due to the extremely wide bandwidth offered to subscribers. In the last decade, there has also been an enormous increase of user data visible in mobile systems. The importance of fiber-optical techniques within the fixed transmission/transport networks of mobile systems is therefore inevitably increasing. This article summarizes a few reasons and gives examples why and how fiber-optic techniques are employed efficiently in second-generation networks.

  6. Precision alignment device

    DOEpatents

    Jones, N.E.

    1988-03-10

    Apparatus for providing automatic alignment of beam devices having an associated structure for directing, collimating, focusing, reflecting, or otherwise modifying the main beam. A reference laser is attached to the structure enclosing the main beam producing apparatus and produces a reference beam substantially parallel to the main beam. Detector modules containing optical switching devices and optical detectors are positioned in the path of the reference beam and are effective to produce an electrical output indicative of the alignment of the main beam. This electrical output drives servomotor operated adjustment screws to adjust the position of elements of the structure associated with the main beam to maintain alignment of the main beam. 5 figs.

  7. Precision alignment device

    DOEpatents

    Jones, Nelson E.

    1990-01-01

    Apparatus for providing automatic alignment of beam devices having an associated structure for directing, collimating, focusing, reflecting, or otherwise modifying the main beam. A reference laser is attached to the structure enclosing the main beam producing apparatus and produces a reference beam substantially parallel to the main beam. Detector modules containing optical switching devices and optical detectors are positioned in the path of the reference beam and are effective to produce an electrical output indicative of the alignment of the main beam. This electrical output drives servomotor operated adjustment screws to adjust the position of elements of the structure associated with the main beam to maintain alignment of the main beam.

  8. Absorber Alignment Measurement Tool for Solar Parabolic Trough Collectors: Preprint

    SciTech Connect

    Stynes, J. K.; Ihas, B.

    2012-04-01

    As we pursue efforts to lower the capital and installation costs of parabolic trough solar collectors, it is essential to maintain high optical performance. While there are many optical tools available to measure the reflector slope errors of parabolic trough solar collectors, there are few tools to measure the absorber alignment. A new method is presented here to measure the absorber alignment in two dimensions to within 0.5 cm. The absorber alignment is measured using a digital camera and four photogrammetric targets. Physical contact with the receiver absorber or glass is not necessary. The alignment of the absorber is measured along its full length so that sagging of the absorber can be quantified with this technique. The resulting absorber alignment measurement provides critical information required to accurately determine the intercept factor of a collector.

  9. Laser-Based Acousto-Optic Uplink Communications Technique

    DTIC Science & Technology

    2003-08-18

    An apparatus for enabling acousto - optic communication comprising an in-water platform comprising means for emitting an acoustic signal to an acousto ...portion of the first interrogation beam and a second laser beam formed from the reflection of the first interrogation beam off of the acousto - optic interaction... optic interaction zone, an in-air platform comprising the ability for transmitting a first optical interrogation beam, the ability for receiving a

  10. Response Surface Methods For Spatially-Resolved Optical Measurement Techniques

    NASA Technical Reports Server (NTRS)

    Danehy, P. M.; Dorrington, A. A.; Cutler, A. D.; DeLoach, R.

    2003-01-01

    Response surface methods (or methodology), RSM, have been applied to improve data quality for two vastly different spatially-resolved optical measurement techniques. In the first application, modern design of experiments (MDOE) methods, including RSM, are employed to map the temperature field in a direct-connect supersonic combustion test facility at NASA Langley Research Center. The laser-based measurement technique known as coherent anti-Stokes Raman spectroscopy (CARS) is used to measure temperature at various locations in the combustor. RSM is then used to develop temperature maps of the flow. Even though the temperature fluctuations at a single point in the flowfield have a standard deviation on the order of 300 K, RSM provides analytic fits to the data having 95% confidence interval half width uncertainties in the fit as low as +/- 30 K. Methods of optimizing future CARS experiments are explored. The second application of RSM is to quantify the shape of a 5-meter diameter, ultra-lightweight, inflatable space antenna at NASA Langley Research Center. Photogrammetry is used to simultaneously measure the shape of the antenna at approximately 500 discrete spatial locations. RSM allows an analytic model to be developed that describes the shape of the majority of the antenna with an uncertainty of 0.4 mm, with 95% confidence. This model would allow a quantitative comparison between the actual shape of the antenna and the original design shape. Accurately determining this shape also allows confident interpolation between the measured points. Such a model could, for example, be used for ray tracing of radio-frequency waves up to 95 GHz. to predict the performance of the antenna.

  11. Online technique for detecting state of onboard fiber optic gyroscope.

    PubMed

    Miao, Zhiyong; Xu, Dingjie; He, Kunpeng; Pang, Shuwan; Tian, Chunmiao

    2015-02-01

    Although angle random walk (ARW) of fiber optic gyroscope (FOG) has been well modeled and identified before being integrated into the high-accuracy attitude control system of satellite, aging and unexpected failures can affect the performance of FOG after launch, resulting in the variation of ARW coefficient. Therefore, the ARW coefficient can be regarded as an indicator of "state of health" for FOG diagnosis in some sense. The Allan variance method can be used to estimate ARW coefficient of FOG, however, it requires a large amount of data to be stored. Moreover, the procedure of drawing slope lines for estimation is painful. To overcome the barriers, a weighted state-space model that directly models the ARW to obtain a nonlinear state-space model was established for FOG. Then, a neural extended-Kalman filter algorithm was implemented to estimate and track the variation of ARW in real time. The results of experiment show that the proposed approach is valid to detect the state of FOG. Moreover, the proposed technique effectively avoids the storage of data.

  12. Remote sensing of stress using electro-optics imaging technique

    NASA Astrophysics Data System (ADS)

    Chen, Tong; Yuen, Peter; Hong, Kan; Tsitiridis, Aristeidis; Kam, Firmin; Jackman, James; James, David; Richardson, Mark; Oxford, William; Piper, Jonathan; Thomas, Francis; Lightman, Stafford

    2009-09-01

    Emotional or physical stresses induce a surge of adrenaline in the blood stream under the command of the sympathetic nerve system, which, cannot be suppressed by training. The onset of this alleviated level of adrenaline triggers a number of physiological chain reactions in the body, such as dilation of pupil and an increased feed of blood to muscles etc. This paper reports for the first time how Electro-Optics (EO) technologies such as hyperspectral [1,2] and thermal imaging[3] methods can be used for the detection of stress remotely. Preliminary result using hyperspectral imaging technique has shown a positive identification of stress through an elevation of haemoglobin oxygenation saturation level in the facial region, and the effect is seen more prominently for the physical stressor than the emotional one. However, all results presented so far in this work have been interpreted together with the base line information as the reference point, and that really has limited the overall usefulness of the developing technology. The present result has highlighted this drawback and it prompts for the need of a quantitative assessment of the oxygenation saturation and to correlate it directly with the stress level as the top priority of the next stage of research.

  13. Online technique for detecting state of onboard fiber optic gyroscope

    SciTech Connect

    Miao, Zhiyong; He, Kunpeng Pang, Shuwan; Xu, Dingjie; Tian, Chunmiao

    2015-02-15

    Although angle random walk (ARW) of fiber optic gyroscope (FOG) has been well modeled and identified before being integrated into the high-accuracy attitude control system of satellite, aging and unexpected failures can affect the performance of FOG after launch, resulting in the variation of ARW coefficient. Therefore, the ARW coefficient can be regarded as an indicator of “state of health” for FOG diagnosis in some sense. The Allan variance method can be used to estimate ARW coefficient of FOG, however, it requires a large amount of data to be stored. Moreover, the procedure of drawing slope lines for estimation is painful. To overcome the barriers, a weighted state-space model that directly models the ARW to obtain a nonlinear state-space model was established for FOG. Then, a neural extended-Kalman filter algorithm was implemented to estimate and track the variation of ARW in real time. The results of experiment show that the proposed approach is valid to detect the state of FOG. Moreover, the proposed technique effectively avoids the storage of data.

  14. Spatial-temporal demodulation technique for heterodyne optical scanning holography

    NASA Astrophysics Data System (ADS)

    Liu, Jung-Ping; Luo, Dao-Zheng; Lu, Sheng-Hua

    2015-05-01

    In optical scanning holography (OSH), the object is raster scanned by a heterodyne fringe pattern. The light scattered from the object is detected by a photodetector. Traditionally, the photo-electric signal is demodulated by a dual-channel lock-in amplifier (LIA) to extract a complex hologram. The use of LIA complicates the detection module of the system and increases the cost, especially when the heterodyne frequency is high. In this paper, an alternative demodulation method called a spatial-temporal demodulation technique (STDT) is studied. In STDT, the photo-electric temporal signal is directly digitized as scanning lines. The spectrum of each scanning line is band-pass filtered to remove the zeroth-order term and the complex conjugate term. Finally, a complex hologram is obtained from the filtered spectrum. The first merit of STDT is that the phase of the demodulated complex hologram is insensitive to the modulation error. Thus it is easily applied to the applications of particle holography. Besides, the bandwidth of the zeroth-order term in STDT is narrow, which allows the system to be operated in a wide range of heterodyne frequency. This feature enables STDT-based OSH to be applied in low-cost and high-speed dynamic holographic imaging.

  15. Alignment and Integration of Lightweight Mirror Segments

    NASA Technical Reports Server (NTRS)

    Evans, Tyler; Biskach, Michael; Mazzarella, Jim; McClelland, Ryan; Saha, Timo; Zhang, Will; Chan, Kai-Wing

    2011-01-01

    The optics for the International X-Ray Observatory (IXO) require alignment and integration of about fourteen thousand thin mirror segments to achieve the mission goal of 3.0 square meters of effective area at 1.25 keV with an angular resolution of five arc-seconds. These mirror segments are 0.4 mm thick, and 200 to 400 mm in size, which makes it difficult not to impart distortion at the sub-arc-second level. This paper outlines the precise alignment, permanent bonding, and verification testing techniques developed at NASA's Goddard Space Flight Center (GSFC). Improvements in alignment include new hardware and automation software. Improvements in bonding include two module new simulators to bond mirrors into, a glass housing for proving single pair bonding, and a Kovar module for bonding multiple pairs of mirrors. Three separate bonding trials were x-ray tested producing results meeting the requirement of sub ten arc-second alignment. This paper will highlight these recent advances in alignment, testing, and bonding techniques and the exciting developments in thin x-ray optic technology development.

  16. Wave-Coupled Millimeter-Wave Electro-Optic Techniques

    DTIC Science & Technology

    2001-03-01

    This report details results on two antenna-coupled millimeter-wave electro - optic modulators, the slot-vee antenna-coupled modulator and a 94 GHz...study of the effects of velocity mismatch on linearized electro - optic modulators was made and the results published. A key result was that directional...drift in electro - optic modulators was made and protons were determined to be the cause. Several inventions were made to reduce or eliminate proton-caused bias drift.

  17. Analysis of an Optical Channelization Technique for Microwave Applications

    DTIC Science & Technology

    2007-06-27

    based on what portion of that optical spectrum reaches a given photodetector. We model the MZM as an ideal, balanced device and apply a complex...L M N O B P Q Fig. 2. Several of the most significant optical field components resulting from two-tone modulation on a balanced Mach-Zehnder...channelizer is not an issue since it is assumed that optical local oscillators will be added to the channelizer outputs prior to photodetection . The

  18. Study of optical techniques for the Ames unitary wind tunnel, part 7

    NASA Technical Reports Server (NTRS)

    Lee, George

    1993-01-01

    A summary of optical techniques for the Ames Unitary Plan wind tunnels are discussed. Six optical techniques were studied: Schlieren, light sheet and laser vapor screen, angle of attack, model deformation, infrared imagery, and digital image processing. The study includes surveys and reviews of wind tunnel optical techniques, some conceptual designs, and recommendations for use of optical methods in the Ames Unitary Plan wind tunnels. Particular emphasis was placed on searching for systems developed for wind tunnel use and on commercial systems which could be readily adapted for wind tunnels. This final report is to summarize the major results and recommendations.

  19. Axial Phase-Darkfield-Contrast (APDC), a new technique for variable optical contrasting in light microscopy.

    PubMed

    Piper, T; Piper, J

    2012-09-01

    Axial phase-darkfield-contrast (APDC) has been developed as an illumination technique in light microscopy which promises significant improvements and a higher variability in imaging of several transparent 'problem specimens'. With this method, a phase contrast image is optically superimposed on an axial darkfield image so that a partial image based on the principal zeroth order maximum (phase contrast) interferes with an image, which is based on the secondary maxima (axial darkfield). The background brightness and character of the resulting image can be continuously modulated from a phase contrast-dominated to a darkfield-dominated character. In order to achieve this illumination mode, normal objectives for phase contrast have to be fitted with an additional central light stopper needed for axial (central) darkfield illumination. In corresponding condenser light masks, a small perforation has to be added in the centre of the phase contrast providing light annulus. These light modulating elements are properly aligned when the central perforation is congruent with the objective's light stop and the light annulus is conjugate with the phase ring. The breadth of the condenser light annulus and thus the intensity of the phase contrast partial image can be regulated with the aperture diaphragm. Additional contrast effects can be achieved when both illuminating light components are filtered at different colours. In this technique, the axial resolution (depth of field) is significantly enhanced and the specimen's three-dimensional appearance is accentuated with improved clarity as well as fine details at the given resolution limit. Typical artefacts associated with phase contrast and darkfield illumination are reduced in our methods.

  20. Differential Deposition Technique for Figure Corrections in Grazing Incidence X-ray Optics

    NASA Technical Reports Server (NTRS)

    Kilaru, Kiranmayee; Ramsey, Brian D.; Gubarev, Mikhail

    2009-01-01

    A differential deposition technique is being developed to correct the low- and mid-spatial-frequency deviations in the axial figure profile of Wolter type grazing incidence X-ray optics. These deviations arise due to various factors in the fabrication process and they degrade the performance of the optics by limiting the achievable angular resolution. In the differential deposition technique, material of varying thickness is selectively deposited along the length of the optic to minimize these deviations, thereby improving the overall figure. High resolution focusing optics being developed at MSFC for small animal radionuclide imaging are being coated to test the differential deposition technique. The required spatial resolution for these optics is 100 m. This base resolution is achievable with the regular electroform-nickel-replication fabrication technique used at MSFC. However, by improving the figure quality of the optics through differential deposition, we aim at significantly improving the resolution beyond this value.

  1. Transferring vertically aligned carbon nanotubes onto a polymeric substrate using a hot embossing technique for microfluidic applications

    PubMed Central

    Mathur, A.; Roy, S. S.; McLaughlin, J. A.

    2010-01-01

    We explored the hot embossing method for transferring vertically aligned carbon nanotubes (CNTs) into microfluidic channels, fabricated on poly-methyl-methacrylate (PMMA). Patterned and unpatterned CNTs were synthesized by microwave plasma-enhanced chemical vapour deposition on silicon to work as a stamp. For hot embossing, 115°C and 1 kN force for 2 min were found to be the most suitable parameters for the complete transfer of aligned CNTs on the PMMA microchannel. Raman and SEM studies were used to analyse the microstructure of CNTs before and after hot embossing. The PMMA microparticles with dimensions (approx. 10 µm in diameter) similar to red blood cells were successfully filtered using laminar flow through these microfluidic channels. Finally, a microfluidic-based point-of-care device for blood filtration and detection of bio-molecules is drawn schematically. PMID:20147316

  2. In situ growth of aligned CdS nanowire arrays on Cd foil and their optical and electron field emission properties

    SciTech Connect

    Qian, G. X.; Hung, T. F.; Chu, Paul K.; Huo, K. F.; Fu, J. J.

    2008-07-01

    Aligned CdS nanowire arrays have been fabricated directly on a Cd foil via a simple solvothermal method. The metal Cd foil serves as both the Cd source and substrate during fabrication of the aligned CdS nanowire arrays. The morphology, structure, and composition of the samples are characterized by x-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, energy-dispersive x-ray spectroscopy, and selected-area electron diffraction, and the results reveal the formation of aligned single-crystalline CdS nanowires with uniform diameters of 20-40 nm. The photoluminescence and Raman spectra disclose the optical properties of the products and the possible growth mechanism is suggested. The electron field emission properties are also investigated and analyzed. The screening effect is observed to play a vital role in the electron field emission properties due to the coalescent ends of the nanowires. The simple synthesis methodology in conjunction with the good field emission and optical properties makes the materials both scientifically and technologically interesting.

  3. Optical See-Through Head Mounted Display Direct Linear Transformation Calibration Robustness in the Presence of User Alignment Noise

    NASA Technical Reports Server (NTRS)

    Axholt, Magnus; Skoglund, Martin; Peterson, Stephen D.; Cooper, Matthew D.; Schoen, Thomas B.; Gustafsson, Fredrik; Ynnerman, Anders; Ellis, Stephen R.

    2010-01-01

    Augmented Reality (AR) is a technique by which computer generated signals synthesize impressions that are made to coexist with the surrounding real world as perceived by the user. Human smell, taste, touch and hearing can all be augmented, but most commonly AR refers to the human vision being overlaid with information otherwise not readily available to the user. A correct calibration is important on an application level, ensuring that e.g. data labels are presented at correct locations, but also on a system level to enable display techniques such as stereoscopy to function properly [SOURCE]. Thus, vital to AR, calibration methodology is an important research area. While great achievements already have been made, there are some properties in current calibration methods for augmenting vision which do not translate from its traditional use in automated cameras calibration to its use with a human operator. This paper uses a Monte Carlo simulation of a standard direct linear transformation camera calibration to investigate how user introduced head orientation noise affects the parameter estimation during a calibration procedure of an optical see-through head mounted display.

  4. Surface properties of hard protective coatings studied by optical techniques

    NASA Astrophysics Data System (ADS)

    Jaglarz, Janusz; Wolska, N.; Mitura, K.; Duraj, R.; Marszalek, K. W.; El Kouari, Y.

    2016-06-01

    The paper describes optical study of SiC, C and NiC layers deposited on Si substrates by double beam ion sputtering (DBIS) method. The following optical methods: ellipsometry, bidirectional reflection distribution function (BRDF) and total integrated scattering (TIS) studies have been applied. The obtained results allowed us to determine the refractive indices, extinction coefficients and the roughness parameters of DBIS films. Also surface profiles of optical constants determined from scanning ellipsometric measurements have been presented. The power spectral density functions (PSD) of surface roughness for studied samples have been determined. The influence of the deposition technology on film topography has been discussed.

  5. Advanced materials and techniques for fibre-optic sensing

    NASA Astrophysics Data System (ADS)

    Henderson, Philip J.

    2014-06-01

    Fibre-optic monitoring systems came of age in about 1999 upon the emergence of the world's first significant commercialising company - a spin-out from the UK's collaborative MAST project. By using embedded fibre-optic technology, the MAST project successfully measured transient strain within high-performance composite yacht masts. Since then, applications have extended from smart composites into civil engineering, energy, military, aerospace, medicine and other sectors. Fibre-optic sensors come in various forms, and may be subject to embedment, retrofitting, and remote interrogation. The unique challenges presented by each implementation require careful scrutiny before widespread adoption can take place. Accordingly, various aspects of design and reliability are discussed spanning a range of representative technologies that include resonant microsilicon structures, MEMS, Bragg gratings, advanced forms of spectroscopy, and modern trends in nanotechnology. Keywords: Fibre-optic sensors, fibre Bragg gratings, MEMS, MOEMS, nanotechnology, plasmon.

  6. An Approach to Identifying the Effect of Technique Asymmetries on Body Alignment in Swimming Exemplified by a Case Study of a Breaststroke Swimmer

    PubMed Central

    Sanders, Ross H.; Fairweather, Malcolm M.; Alcock, Alison; McCabe, Carla B.

    2015-01-01

    Despite the importance of maintaining good alignment to minimize resistive drag in swimming there is a paucity of literature relating to the effect of technique asymmetries on rotations of the body about a vertical axis (yaw). The purpose of this paper was to present an approach to analyzing the effect of technique asymmetries on rotations in swimming, exemplifying the process with a case study of a breaststroke swimmer. The kinematics and angular kinetics of an elite female international breaststroke swimmer performing a ‘fatigue set’ of four 100m swims were derived from digitized three-dimensional video data using a 13 segment body model. Personalised anthropometric data required to quantify accurately segment and whole body centres of mass and segmental angular momentum were obtained by the elliptical zone method. Five episodes of torques producing yaw occurred in the stroke cycle sampled for each 100m swim of this swimmer. These torques were linked to bilateral differences in upper limb kinematics during 1) out-sweep; 2) in-sweep; 3) upper limb recovery; and lower limb kinematics during 4) Lower limb recovery and 5) the kick. It has been shown that by quantifying whole body torques, in conjunction with the kinematic movement patterns, the effect of technique asymmetries on body alignment can be assessed. Assessment of individual swimmers in this manner provides a solid foundation for planning interventions in strength, flexibility, and technique to improve alignment and performance. Key points A unique (not been attempted previously) study of yaw in breaststroke swimming that yields new knowledge of how technique and strength asymmetries affects body alignment. Establishes an approach to investigation of yaw in swimming using 3D videography and inverse dynamics. Exemplifies the approach with a case study. The case study illustrated the potential of the approach to enable detailed assessment of yaw and to explain how the yaw is produced in terms of the

  7. An approach to identifying the effect of technique asymmetries on body alignment in swimming exemplified by a case study of a breaststroke swimmer.

    PubMed

    Sanders, Ross H; Fairweather, Malcolm M; Alcock, Alison; McCabe, Carla B

    2015-06-01

    Despite the importance of maintaining good alignment to minimize resistive drag in swimming there is a paucity of literature relating to the effect of technique asymmetries on rotations of the body about a vertical axis (yaw). The purpose of this paper was to present an approach to analyzing the effect of technique asymmetries on rotations in swimming, exemplifying the process with a case study of a breaststroke swimmer. The kinematics and angular kinetics of an elite female international breaststroke swimmer performing a 'fatigue set' of four 100m swims were derived from digitized three-dimensional video data using a 13 segment body model. Personalised anthropometric data required to quantify accurately segment and whole body centres of mass and segmental angular momentum were obtained by the elliptical zone method. Five episodes of torques producing yaw occurred in the stroke cycle sampled for each 100m swim of this swimmer. These torques were linked to bilateral differences in upper limb kinematics during 1) out-sweep; 2) in-sweep; 3) upper limb recovery; and lower limb kinematics during 4) Lower limb recovery and 5) the kick. It has been shown that by quantifying whole body torques, in conjunction with the kinematic movement patterns, the effect of technique asymmetries on body alignment can be assessed. Assessment of individual swimmers in this manner provides a solid foundation for planning interventions in strength, flexibility, and technique to improve alignment and performance. Key pointsA unique (not been attempted previously) study of yaw in breaststroke swimming that yields new knowledge of how technique and strength asymmetries affects body alignment.Establishes an approach to investigation of yaw in swimming using 3D videography and inverse dynamics.Exemplifies the approach with a case study. The case study illustrated the potential of the approach to enable detailed assessment of yaw and to explain how the yaw is produced in terms of the asymmetries

  8. Development of differential deposition technique for figure corrections in grazing incidence x-ray optics

    NASA Astrophysics Data System (ADS)

    Kilaru, Kiranmayee; Ramsey, Brian D.; Gubarev, Mikhail V.

    2009-08-01

    A differential deposition technique is being developed to correct the low- and mid-spatial-frequency deviations in the axial figure profile of Wolter-type grazing-incidence X-ray optics. These deviations arise due to various factors in the fabrication process and they degrade the performance of optics by limiting the achievable angular resolution. In the differential deposition technique, material is selectively deposited in varying thickness along the length of the optic to minimize these deviations, thereby improving the overall figure. The process is being tested on focusing X-ray optics being developed at MSFC for small-animal radionuclide imaging. The required spatial resolution for these optics is 100 μm (30 arc secs), which can be achieved with the electroformnickel- replication fabrication technique regularly employed at MSFC. However, by improving the figure quality of the optics through differential deposition, we aim to significantly improve the resolution beyond this value.

  9. Centrally controlled self-healing wavelength division multiplexing passive optical network based on optical carrier suppression technique

    NASA Astrophysics Data System (ADS)

    Zhu, Min; Zhang, Jiao; Sun, Xiaohan

    2015-12-01

    We proposed and demonstrated a centrally controlled and self-healing wavelength division multiplexing passive optical network with colorless optical network units (ONUs) based on optical carrier suppression technique. By switching the affected data in the OCS signal sideband to an alternate protection path, only one optical switch is provisioned at the optical line terminal, which is controlled by a logic control circuit upon monitoring of power outage on the working path. The proposed scheme can reliably protect against both distribution and feeder fiber failures. Moreover, gain-saturated reflective semiconductor optical amplifiers are used as colorless transmitters in ONUs. The protection scheme feasibility and system performances are experimentally verified with 10 Gb/s downstream and 1.25 Gb/s upstream data in both working and protection modes. The protection switching time was measured to be around 1 ms.

  10. Treatment outcome and efficacy of an aligner technique – regarding incisor torque, premolar derotation and molar distalization

    PubMed Central

    2014-01-01

    Background The aim of this study was to investigate the efficacy of orthodontic treatment using the Invisalign® system. Particularly, we analyzed the influence of auxiliaries (Attachment/Power Ridge) as well as the staging (movement per aligner) on treatment efficacy. Methods We reviewed the tooth movements of 30 consecutive patients who required orthodontic treatment with Invisalign®. In all patients, one of the following tooth movements was performed: (1) Incisor Torque >10°, (2) Premolar derotation >10° (3) Molar distalization >1.5 mm. The groups (1)-(3) were subdivided: in the first subgroup (a) the movements were supported with the use of an attachment, while in the subgroup (b) no auxiliaries were used (except incisor torque, in which Power Ridges were used). All tooth movements were performed in a split-mouth design. To analyze the clinical efficacy, pre-treatment and final plaster cast models were laser-scanned and the achieved tooth movement was determined by way of a surface/surface matching algorithm. The results were compared with the amount of tooth movement predicted by ClinCheck®. Results The overall mean efficacy was 59% (SD = 0.2). The mean accuracy for upper incisor torque was 42% (SD = 0.2). Premolar derotation showed the lowest accuracy with approximately 40% (SD = 0.3). Distalization of an upper molar was the most effective movement, with efficacy approximately 87% (SD = 0.2). Conclusion Incisor torque, premolar derotation and molar distalization can be performed using Invisalign® aligners. The staging (movement/aligner) and the total amount of planned movement have an significant impact on treatment efficacy. PMID:24923279

  11. Micro/nanoscale self-aligned optical couplings of the self-organized lightwave network (SOLNET) formed by excitation lights from outside

    NASA Astrophysics Data System (ADS)

    Yoshimura, Tetsuzo; Nawata, Hideyuki

    2017-01-01

    The self-organized lightwave network (SOLNET) provides "optical solder," which enables self-aligned optical couplings between misaligned optical devices with different core sizes. We propose a low-cost SOLNET formation method, in which write beams are generated within optical devices by excitation lights from outside. Simulations based on the finite-difference time-domain method reveal that the two-photon processes enhance optical-solder capabilities. In couplings between 600-nm-wide waveguides opposed with 32-μm distance a wide lateral misalignment tolerance of 2 μm to maintain <1 dB loss at 650 nm in wavelength is obtained. The coupling loss at 1-μm lateral misalignment is 0.4 dB. In couplings between 3-μm-wide and 600-nm-wide waveguides, losses at 650 nm are 0.1 dB for no misalignments and 0.9 dB for 1-μm misalignment. These results suggest that SOLNETs provide optical solder with mode size converting functions.

  12. Dark Field Technology - A Practical Approach To Local Alignment

    NASA Astrophysics Data System (ADS)

    Beaulieu, David R.; Hellebrekers, Paul P.

    1987-01-01

    A fully automated direct reticle reference alignment system for use in step and repeat camera systems is described. The technique, first outlined by Janus S. Wilczynski, ("Optical Step and Repeat Camera with Dark Field Alignment", J. Vac. Technol., 16(6), Nov./Dec. 1979), has been implemented on GCA Corporation's DSW Wafer Stepper. Results from various process levels covering the typical CMOS process have shown that better than ±0.2μm alignment accuracy can be obtained with minimal process sensitivity. The technique employs fixed illumination and microscope optics to achieve excellent registration stability and maintenance-free operation. Latent image techniques can be exploited for intra-field, grid and focus characterization.

  13. Fine optical alignment correction of astronomical spectrographs via in-situ full-field moment-based wavefront sensing

    NASA Astrophysics Data System (ADS)

    Lee, Hanshin; Hill, Gary J.; Tuttle, Sarah E.; Vattiat, Brian L.

    2012-09-01

    The image moment-based wavefront sensing (IWFS) utilizes moments of focus-modulated focal plane images to determine modal wavefront aberrations. This permits fast, easy, and accurate measurement of wavefront error (WFE) on any available finite-sized isolated targets across the entire focal plane (FP) of an imaging system, thereby allowing not only in-situ full-field image quality assessment, but also deterministic fine alignment correction of the imaging system. We present an experimental demonstration where fine alignment correction of a fast camera system in a fiber-fed astronomical spectrograph, called VIRUS, is accomplished by using IWFS.

  14. MP-Align: alignment of metabolic pathways

    PubMed Central

    2014-01-01

    Background Comparing the metabolic pathways of different species is useful for understanding metabolic functions and can help in studying diseases and engineering drugs. Several comparison techniques for metabolic pathways have been introduced in the literature as a first attempt in this direction. The approaches are based on some simplified representation of metabolic pathways and on a related definition of a similarity score (or distance measure) between two pathways. More recent comparative research focuses on alignment techniques that can identify similar parts between pathways. Results We propose a methodology for the pairwise comparison and alignment of metabolic pathways that aims at providing the largest conserved substructure of the pathways under consideration. The proposed methodology has been implemented in a tool called MP-Align, which has been used to perform several validation tests. The results showed that our similarity score makes it possible to discriminate between different domains and to reconstruct a meaningful phylogeny from metabolic data. The results further demonstrate that our alignment algorithm correctly identifies subpathways sharing a common biological function. Conclusion The results of the validation tests performed with MP-Align are encouraging. A comparison with another proposal in the literature showed that our alignment algorithm is particularly well-suited to finding the largest conserved subpathway of the pathways under examination. PMID:24886436

  15. Characterization of optical components using contact and non-contact interferometry techniques: advanced metrology for optical components

    NASA Astrophysics Data System (ADS)

    Yu, Yang; Conroy, Mike; Smith, Richard

    2012-10-01

    Advanced metrology plays an important role in the research, production and quality control of optical components. With surface finish, form error and other parameter specifications becoming more stringent, precision measurements are increasingly demanded by optics manufacturers and users. The modern metrologist now has both contact and noncontact measurement solutions available and a combination of these techniques now provides a more detailed understanding of optical components. Phase Grating Interferometry (PGI) with sub-nanometre vertical resolution and sub-micron lateral resolution can provide detailed characterization of a wide range of components including shallow and steep-sided optics. PGI is ideal for precision form measurement of a comprehensive range of lenses, moulds and other spherical or aspheric products. Because of the complex nature of these components, especially precision aspheric and asphero-diffractive optics, control of the form is vital to ensure they perform correctly. Recent hardware and software developments now make it possible to gain a better understanding and control of the form and function of this optics. Another change is the use of high speed 3D non-contact measurement of optics which is becoming more popular. Often scanning interferometric techniques such as coherence correlation interferometry (CCI) can be used to study components not suited to 2D contact analysis, including fragile surfaces and structured surfaces. Scanning interferometry can also be used to measure film thickness and uniformity of any coating present. In this paper the use of both PGI and CCI to measure optical lenses and coatings is discussed.

  16. Beaconless adaptive-optics technique for HEL beam control

    NASA Astrophysics Data System (ADS)

    Khizhnyak, Anatoliy; Markov, Vladimir

    2016-05-01

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

  17. Image Correlation Method for DNA Sequence Alignment

    PubMed Central

    Curilem Saldías, Millaray; Villarroel Sassarini, Felipe; Muñoz Poblete, Carlos; Vargas Vásquez, Asticio; Maureira Butler, Iván

    2012-01-01

    The complexity of searches and the volume of genomic data make sequence alignment one of bioinformatics most active research areas. New alignment approaches have incorporated digital signal processing techniques. Among these, correlation methods are highly sensitive. This paper proposes a novel sequence alignment method based on 2-dimensional images, where each nucleic acid base is represented as a fixed gray intensity pixel. Query and known database sequences are coded to their pixel representation and sequence alignment is handled as object recognition in a scene problem. Query and database become object and scene, respectively. An image correlation process is carried out in order to search for the best match between them. Given that this procedure can be implemented in an optical correlator, the correlation could eventually be accomplished at light speed. This paper shows an initial research stage where results were “digitally” obtained by simulating an optical correlation of DNA sequences represented as images. A total of 303 queries (variable lengths from 50 to 4500 base pairs) and 100 scenes represented by 100 x 100 images each (in total, one million base pair database) were considered for the image correlation analysis. The results showed that correlations reached very high sensitivity (99.01%), specificity (98.99%) and outperformed BLAST when mutation numbers increased. However, digital correlation processes were hundred times slower than BLAST. We are currently starting an initiative to evaluate the correlation speed process of a real experimental optical correlator. By doing this, we expect to fully exploit optical correlation light properties. As the optical correlator works jointly with the computer, digital algorithms should also be optimized. The results presented in this paper are encouraging and support the study of image correlation methods on sequence alignment. PMID:22761742

  18. Image correlation method for DNA sequence alignment.

    PubMed

    Curilem Saldías, Millaray; Villarroel Sassarini, Felipe; Muñoz Poblete, Carlos; Vargas Vásquez, Asticio; Maureira Butler, Iván

    2012-01-01

    The complexity of searches and the volume of genomic data make sequence alignment one of bioinformatics most active research areas. New alignment approaches have incorporated digital signal processing techniques. Among these, correlation methods are highly sensitive. This paper proposes a novel sequence alignment method based on 2-dimensional images, where each nucleic acid base is represented as a fixed gray intensity pixel. Query and known database sequences are coded to their pixel representation and sequence alignment is handled as object recognition in a scene problem. Query and database become object and scene, respectively. An image correlation process is carried out in order to search for the best match between them. Given that this procedure can be implemented in an optical correlator, the correlation could eventually be accomplished at light speed. This paper shows an initial research stage where results were "digitally" obtained by simulating an optical correlation of DNA sequences represented as images. A total of 303 queries (variable lengths from 50 to 4500 base pairs) and 100 scenes represented by 100 x 100 images each (in total, one million base pair database) were considered for the image correlation analysis. The results showed that correlations reached very high sensitivity (99.01%), specificity (98.99%) and outperformed BLAST when mutation numbers increased. However, digital correlation processes were hundred times slower than BLAST. We are currently starting an initiative to evaluate the correlation speed process of a real experimental optical correlator. By doing this, we expect to fully exploit optical correlation light properties. As the optical correlator works jointly with the computer, digital algorithms should also be optimized. The results presented in this paper are encouraging and support the study of image correlation methods on sequence alignment.

  19. Ultrafast optical technique for the characterization of altered materials

    DOEpatents

    Maris, Humphrey J.

    1998-01-01

    Disclosed herein is a method and a system for non-destructively examining a semiconductor sample (30) having at least one localized region underlying a surface (30a) through into which a selected chemical species has been implanted or diffused. A first step induces at least one transient time-varying change in optical constants of the sample at a location at or near to a surface of the sample. A second step measures a response of the sample to an optical probe beam, either pulsed or continuous wave, at least during a time that the optical constants are varying. A third step associates the measured response with at least one of chemical species concentration, chemical species type, implant energy, a presence or absence of an introduced chemical species region at the location, and a presence or absence of implant-related damage. The method and apparatus in accordance with this invention can be employed in conjunction with a measurement of one or more of the following effects arising from a time-dependent change in the optical constants of the sample due to the application of at least one pump pulse: (a) a change in reflected intensity; (b) a change in transmitted intensity; (c) a change in a polarization state of the reflected and/or transmitted light; (d) a change in the optical phase of the reflected and/or transmitted light; (e) a change in direction of the reflected and/or transmitted light; and (f) a change in optical path length between the sample's surface and a detector.

  20. Detection and Alignment of 3D Domain Swapping Proteins Using Angle-Distance Image-Based Secondary Structural Matching Techniques

    PubMed Central

    Wang, Hsin-Wei; Hsu, Yen-Chu; Hwang, Jenn-Kang; Lyu, Ping-Chiang; Pai, Tun-Wen; Tang, Chuan Yi

    2010-01-01

    This work presents a novel detection method for three-dimensional domain swapping (DS), a mechanism for forming protein quaternary structures that can be visualized as if monomers had “opened” their “closed” structures and exchanged the opened portion to form intertwined oligomers. Since the first report of DS in the mid 1990s, an increasing number of identified cases has led to the postulation that DS might occur in a protein with an unconstrained terminus under appropriate conditions. DS may play important roles in the molecular evolution and functional regulation of proteins and the formation of depositions in Alzheimer's and prion diseases. Moreover, it is promising for designing auto-assembling biomaterials. Despite the increasing interest in DS, related bioinformatics methods are rarely available. Owing to a dramatic conformational difference between the monomeric/closed and oligomeric/open forms, conventional structural comparison methods are inadequate for detecting DS. Hence, there is also a lack of comprehensive datasets for studying DS. Based on angle-distance (A-D) image transformations of secondary structural elements (SSEs), specific patterns within A-D images can be recognized and classified for structural similarities. In this work, a matching algorithm to extract corresponding SSE pairs from A-D images and a novel DS score have been designed and demonstrated to be applicable to the detection of DS relationships. The Matthews correlation coefficient (MCC) and sensitivity of the proposed DS-detecting method were higher than 0.81 even when the sequence identities of the proteins examined were lower than 10%. On average, the alignment percentage and root-mean-square distance (RMSD) computed by the proposed method were 90% and 1.8Å for a set of 1,211 DS-related pairs of proteins. The performances of structural alignments remain high and stable for DS-related homologs with less than 10% sequence identities. In addition, the quality of its hinge

  1. Fiber optic sensor having dual simultaneous sensitivities employing mode ring technique

    NASA Astrophysics Data System (ADS)

    Dekate, Sachin Narahari

    Fiber optic interferometric sensors have an extremely high maximum sensitivity when compared to fiber optic intensity based sensors. Their disadvantage is the complex and expensive signal demodulation techniques that are employed due to their multi-valued output signal in addition to zero-sensitivity at some measurand values. Employing two interferometric sensors of different sensitivity allows an extended range of operation with relatively high sensitivity, however; the two sensors can never be placed at the same exact spatial location. This dissertation documents the dual-sensitivity fiber optic strain sensor which provides two simultaneous outputs of different sensitivity enabling the unambiguous use of interferometric sensors over an extended range. The dual-sensitivity fiber optic strain sensor has one sensing region and therefore the measurand is sensed at one location. The dual-sensitivity fiber optic strain sensor combines two fiber optic sensor architectures: Two-Mode fiber optic interferometric strain sensor (low sensitivity) and the Mach-Zehnder fiber optic interferometric strain sensor (high sensitivity). The dual-sensitivity fiber optic strain sensor also employs the end-etched fiber technique that enables the separation of modes. This technique allows the separated modes to be recombined in inter-mode (different mode order interference yielding low sensitivity output) and intra-mode (same mode order interference yielding high sensitivity output) interference configurations. One sensing region, dual simultaneous sensitivities and the use of end-etched fiber for sensing applications are some of the unique features of the dual-sensitivity fiber optic strain sensor.

  2. Validation and qualification of surface-applied fibre optic strain sensors using application-independent optical techniques

    NASA Astrophysics Data System (ADS)

    Schukar, Vivien G.; Kadoke, Daniel; Kusche, Nadine; Münzenberger, Sven; Gründer, Klaus-Peter; Habel, Wolfgang R.

    2012-08-01

    Surface-applied fibre optic strain sensors were investigated using a unique validation facility equipped with application-independent optical reference systems. First, different adhesives for the sensor's application were analysed regarding their material properties. Measurements resulting from conventional measurement techniques, such as thermo-mechanical analysis and dynamic mechanical analysis, were compared with measurements resulting from digital image correlation, which has the advantage of being a non-contact technique. Second, fibre optic strain sensors were applied to test specimens with the selected adhesives. Their strain-transfer mechanism was analysed in comparison with conventional strain gauges. Relative movements between the applied sensor and the test specimen were visualized easily using optical reference methods, digital image correlation and electronic speckle pattern interferometry. Conventional strain gauges showed limited opportunities for an objective strain-transfer analysis because they are also affected by application conditions.

  3. Correction of Phase Distortion by Nonlinear Optical Techniques

    DTIC Science & Technology

    1979-03-01

    experimentally that the fraction of nonconju- gato return when using SBS for correction is below measurement limits. • Developed systems applications...saturation 2 properties at optical power densities of less than 500 mW/cm" at 488 nm + 2 (Ar laser) and at slightly higher powers (^ 2 W/cm ) at SOI nm

  4. Optical microphone with fiber Bragg grating and signal processing techniques

    NASA Astrophysics Data System (ADS)

    Tosi, Daniele; Olivero, Massimo; Perrone, Guido

    2008-06-01

    In this paper, we discuss the realization of an optical microphone array using fiber Bragg gratings as sensing elements. The wavelength shift induced by acoustic waves perturbing the sensing Bragg grating is transduced into an intensity modulation. The interrogation unit is based on a fixed-wavelength laser source and - as receiver - a photodetector with proper amplification; the system has been implemented using devices for standard optical communications, achieving a low-cost interrogator. One of the advantages of the proposed approach is that no voltage-to-strain calibration is required for tracking dynamic shifts. The optical sensor is complemented by signal processing tools, including a data-dependent frequency estimator and adaptive filters, in order to improve the frequency-domain analysis and mitigate the effects of disturbances. Feasibility and performances of the optical system have been tested measuring the output of a loudspeaker. With this configuration, the sensor is capable of correctly detecting sounds up to 3 kHz, with a frequency response that exhibits a top sensitivity within the range 200-500 Hz; single-frequency input sounds inducing an axial strain higher than ~10nɛ are correctly detected. The repeatability range is ~0.1%. The sensor has also been applied for the detection of pulsed stimuli generated from a metronome.

  5. On the alignment for precession electron diffraction

    PubMed Central

    Liao, Yifeng; Marks, Laurence D.

    2013-01-01

    Precession electron diffraction has seen a fast increase in its adoption as a technique for solving crystallographic structures as well as an alternative to conventional selected-area and converged-beam diffraction methods. One of the key issues of precession is the pivot point alignment, as a stationary apparent beam does not guarantee a fixed pivot point. A large precession tilt angle, along with pre-field and post-field misalignment, induces shift in the image plane. We point out here that the beam should be aligned to the pre-field optic axis to keep the electron illumination stationary during the rocking process. A practical alignment procedure is suggested with the focus placed on minimizing the beam wandering on the specimen, and is demonstrated for a (110)-oriented silicon single crystal and for a carbide phase (~20 nm in size) within a cast cobalt–chromium–molybdenum alloy. PMID:22634134

  6. Slow Light: Novel Techniques for Optical Signal Processing Based on Stationary Pulses Of Light

    DTIC Science & Technology

    2010-11-21

    confinement of optical fields near metallic nanostructures. When a single CdSe quantum dot is optically excited in close proximity to a silver nanowire ...developed a new all-electrical surface plasmon (SPP) detection technique based on the near-field coupling between guided plasmons and a nanowire field...and a nanowire field-effect transistor and realized a new quantum optical medium based on buffer-gas cooled Rb vapor cell

  7. Passive demodulation of miniature fiber-optic-based interferometric sensors using a time-multiplexing technique.

    PubMed

    Santos, J L; Jackson, D A

    1991-08-01

    A passive demodulation technique suitable for interferometric interrogation of short optical cavities is described. It is based on time multiplexing of two low-finesse Fabry-Perot interferometers subject to the same measurand and with a differential optical phase of pi/2 (modulo 2pi). Independently of the cavity length, two optical outputs in quadrature are generated, which permits signal reading free of fading. The concept is demonstrated for the measurement of vibration using a simple processing scheme.

  8. A technique for detecting and locating polarisation nonuniformities in an anisotropic optical fibre

    SciTech Connect

    Burdin, V V; Konstantinov, Yurii A; Pervadchuk, Vladimir P; Smirnov, A S

    2013-06-30

    One of the most important requirements for optical fibres as waveguiding media is uniformity. Polarisation-maintaining anisotropic fibres contain a special type of nonuniformity, which leads to polarisation cross-talk: optical power is transferred from one polarisation mode to the orthogonal mode. In this paper, we report a technique for detecting and locating such nonuniformities in a PANDA anisotropic single-mode fibre using polarised reflectometry. (fiber optics)

  9. A technique for computation of star magnitudes relative to an optical sensor

    NASA Technical Reports Server (NTRS)

    Rhoads, J. W.

    1972-01-01

    The theory and techniques used to compute star magnitudes relative to any optical detector (such as the Mariner Mars 1971 Canopus star tracker) are described. Results are given relative to various star detectors.

  10. Spatially-resolved spectroscopic technique for measuring optical properties of food

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quantification of optical properties is important to understand light interaction with biological materials, and to develop effective optical sensing techniques for property characterization and quality measurement of food products. This chapter reviews spatially-resolved method, with the focus on f...

  11. Improved optical performance monitoring technique based on nonlinear optics for high-speed WDM Nyquist systems

    NASA Astrophysics Data System (ADS)

    Guesmi, Latifa; Menif, Mourad

    2016-04-01

    The field of fiber optics nonlinearity is more discussed last years due to such remarkable enhancement in the nonlinear processes efficiency. In this paper, and for optical performance monitoring (OPM), a new achievement of nonlinear effects has been investigated. The use of cross-phase modulation (XPM) and four-wave mixing (FWM) effects between input optical signal and inserted continuous-wave probe has proposed for impairments monitoring. Indeed, transmitting a multi-channels phase modulated signal at high data rate (1 Tbps WDM Nyquist NRZ- DP-QPSK) improves the sensitivity and the dynamic range monitoring. It was observed by simulation results that various optical parameters including optical power, wavelength, chromatic dispersion (CD), polarization mode dispersion (PMD), optical signal-to-noise ratio (OSNR), Q-factor and so on, can be monitored. Also, the effect of increasing the channel spacing between WDM signals is studied and proved its use for FWM power monitoring.

  12. A comparison of flat-field measurement techniques for optical streak cameras

    SciTech Connect

    Montgomery, D.S.; Wiedwald, J.D.

    1988-08-01

    A technique for calibrating the flat-field response and geometric distortion of optical steak cameras using high-power lasers and electro-optic pulse shaping hardware was reported previously. The laser hardware provides a temporally-flat light pulse that can be used to calibrate streak cameras operating with sweep durations of 3- 10 ns. Although this technique is successful, the hardware involved is expensive and the process is complex. Based on the analysis of calibrations made at these fast sweep rates, we developed a new technique to measure the flat-field response of an optical streak camera using an array of visible light emitting diodes (LED) and a slow (/approximately/10..mu..s) sweep generator. We will discuss the new slow technique, and will present a comparison between calibration measurements made using the two techniques. 6 refs., 5 figs.

  13. Multiple Fan-Beam Optical Tomography: Modelling Techniques

    PubMed Central

    Rahim, Ruzairi Abdul; Chen, Leong Lai; San, Chan Kok; Rahiman, Mohd Hafiz Fazalul; Fea, Pang Jon

    2009-01-01

    This paper explains in detail the solution to the forward and inverse problem faced in this research. In the forward problem section, the projection geometry and the sensor modelling are discussed. The dimensions, distributions and arrangements of the optical fibre sensors are determined based on the real hardware constructed and these are explained in the projection geometry section. The general idea in sensor modelling is to simulate an artificial environment, but with similar system properties, to predict the actual sensor values for various flow models in the hardware system. The sensitivity maps produced from the solution of the forward problems are important in reconstructing the tomographic image. PMID:22291523

  14. Antenna pointing compensation based on precision optical measurement techniques

    NASA Technical Reports Server (NTRS)

    Schumacher, L. L.; Vivian, H. C.

    1988-01-01

    The pointing control loops of the Deep Space Network 70 meter antennas extend only to the Intermediate Reference Structure (IRS). Thus, distortion of the structure forward of the IRS due to unpredictable environmental loads can result in uncompensated boresight shifts which degrade blind pointing accuracy. A system is described which can provide real time bias commands to the pointing control system to compensate for environmental effects on blind pointing performance. The bias commands are computed in real time based on optical ranging measurements of the structure from the IRS to a number of selected points on the primary and secondary reflectors.

  15. Correction of Phase Distortion by Nonlinear Optical Techniques

    DTIC Science & Technology

    1981-05-01

    ward wave oscillators and distributed feedback lasers, occur even in the presence of pump attenuation. It is obvious that pump depletion effects...a*. Efl v* Z* ^iCVb^^f-V VEfl> (4-3-2) Ik -VE +^ V,2 E - n— p p 2k T p 2nc W {M[(I +1 )En - (E -E*) t...offset techniques. (1) Since the pumps may be arranged to be non-counterpropagating with angle offset techniques, feedback of the pump into the

  16. Integration of infrared and optical imaging techniques for the nondestructive inspection of aeronautic parts

    NASA Astrophysics Data System (ADS)

    López, F.; Sfarra, S.; Ibarra-Castanedo, C.; Paoletti, D.; Maldague, X.

    2015-05-01

    This work focuses in the implementation of infrared and optical imaging techniques for the inspection of aeronautics parts. To this aim, a helicopter blade with known defects is inspected with four different techniques: long pulse thermography, pulsed thermography, digital speckle photography (DSP) and holographic interferometry (HI). The first two techniques belongs to the group of infrared imaging techniques, which are based on the analysis of the infrared thermal patterns in order to detect internal anomalies in the material; whilst the last two (DSP and HI) corresponds to the optical imaging techniques which make use of visible light to measure the material response to an applied stress. Both techniques were applied using the active approach, i.e. an external stimulation is applied in order to produce a gradient in either, the thermal and/or displacement field of the material. The results are then compared in order to evaluate the advantages and limitations of each technique.

  17. Study on metal nanoparticles induced third-order optical nonlinearity in phenylhydrazone derivatives with DFWM technique

    NASA Astrophysics Data System (ADS)

    Sudheesh, P.; Rao, D. Mallikharjuna; Chandrasekharan, K.

    2014-01-01

    The third-order nonlinear optical properties of newly synthesized phenylhydrazone derivatives and the influence of noble metal nanoparticles (Ag & Au) on their nonlinear optical responses were investigated by employing Degenerate Four wave Mixing (DFWM) technique with a 7 nanosecond, 10Hz Nd: YAG laser pulses at 532nm. Metal nanoparticles were prepared by laser ablation and the particle formation was confirmed using UV-Visible spectroscopy, Transmission Electron Microscopy (TEM). The nonlinear optical susceptibility were measured and found to be of the order 10-13esu. The results are encouraging and conclude that the materials are promising candidate for future optical device applications.

  18. Study on metal nanoparticles induced third-order optical nonlinearity in phenylhydrazone derivatives with DFWM technique

    SciTech Connect

    Sudheesh, P.; Chandrasekharan, K.; Rao, D. Mallikharjuna

    2014-01-28

    The third-order nonlinear optical properties of newly synthesized phenylhydrazone derivatives and the influence of noble metal nanoparticles (Ag and Au) on their nonlinear optical responses were investigated by employing Degenerate Four wave Mixing (DFWM) technique with a 7 nanosecond, 10Hz Nd: YAG laser pulses at 532nm. Metal nanoparticles were prepared by laser ablation and the particle formation was confirmed using UV-Visible spectroscopy, Transmission Electron Microscopy (TEM). The nonlinear optical susceptibility were measured and found to be of the order 10{sup −13}esu. The results are encouraging and conclude that the materials are promising candidate for future optical device applications.

  19. Electro-Optical Techniques for Diesel Engine Research

    DTIC Science & Technology

    1977-05-01

    NOTES Available in DDC KEY WORDS (Continue on reverse aide I f necessary and identify by block number) electrooptics Raman spectroscopy mass...spectrometry lasers infrared spectroscopy combustion interferometry mass spectroscopy diagnostic equipment holography resonance absorption diesel engines...fringe techniques (laser anemometry and particle sizing), mass spectroscopy , and resonance absorption. A conventional Army TACOM diesel engine and a

  20. [Optical colonoscopy and virtual colonoscopy: the current role of each technique].

    PubMed

    Bouzas Sierra, R

    2015-01-01

    The importance of optical or conventional colonoscopy in diagnosing colon disease is undisputed. In this context, optical colonoscopy is the gold standard against which other techniques must be validated. Apart from enabling direct inspection of the colonic mucosa, optical colonoscopy enables biopsies and techniques to treat and prevent colorectal cancer. Virtual colonoscopy or CT colonography has been validated in multicenter studies; virtual colonoscopy is as sensitive as optical colonoscopy for the detection of polyps and colon cancer. It is currently the only valid alternative to optical colonoscopy. Its role in patients with medium or high risk of colon cancer is in the process of being defined as multidisciplinary teams gain experience. This article aims to discuss the usefulness of virtual colonoscopy in different clinical situations, emphasizing the situations in which there is enough scientific evidence, and to discuss the controversies surrounding its possible use for population-based screening.

  1. Optical monitoring of anchoring change in vertically aligned thin liquid crystal film for chemical and biological sensor.

    PubMed

    Zou, Yang; Namkung, Jun; Lin, Yongbin; Lindquist, Robert

    2010-04-01

    A significant advance in sensitivity of liquid-crystal (LC)-based chemical and biological sensors can be achieved by actively monitoring anchoring energy change. We simulate the deformation of a LC director with different anchoring energies using the finite element method and the optical properties of the LC film using the finite-difference time-domain method. Polarizing micrographs are collected and compared with simulated textures. Measurement of optical transmission is used to monitor the anchoring change. Experimental and simulation results both demonstrate the optical method can effectively monitor the surface anchoring change due to the presence of targeted analytes.

  2. Z-scan: A simple technique for determination of third-order optical nonlinearity

    SciTech Connect

    Singh, Vijender; Aghamkar, Praveen

    2015-08-28

    Z-scan is a simple experimental technique to measure intensity dependent nonlinear susceptibilities of third-order nonlinear optical materials. This technique is used to measure the sign and magnitude of both real and imaginary part of the third order nonlinear susceptibility (χ{sup (3)}) of nonlinear optical materials. In this paper, we investigate third-order nonlinear optical properties of Ag-polymer composite film by using single beam z-scan technique with Q-switched, frequency doubled Nd: YAG laser (λ=532 nm) at 5 ns pulse. The values of nonlinear absorption coefficient (β), nonlinear refractive index (n{sub 2}) and third-order nonlinear optical susceptibility (χ{sup (3)}) of permethylazine were found to be 9.64 × 10{sup −7} cm/W, 8.55 × 10{sup −12} cm{sup 2}/W and 5.48 × 10{sup −10} esu, respectively.

  3. Digital signal processing techniques for coherent optical communication

    NASA Astrophysics Data System (ADS)

    Goldfarb, Gilad

    Coherent detection with subsequent digital signal processing (DSP) is developed, analyzed theoretically and numerically and experimentally demonstrated in various fiber-optic transmission scenarios. The use of DSP in conjunction with coherent detection unleashes the benefits of coherent detection which rely on the preservaton of full information of the incoming field. These benefits include high receiver sensitivity, the ability to achieve high spectral-efficiency and the use of advanced modulation formats. With the immense advancements in DSP speeds, many of the problems hindering the use of coherent detection in optical transmission systems have been eliminated. Most notably, DSP alleviates the need for hardware phase-locking and polarization tracking, which can now be achieved in the digital domain. The complexity previously associated with coherent detection is hence significantly diminished and coherent detection is once gain considered a feasible detection alternative. In this thesis, several aspects of coherent detection (with or without subsequent DSP) are addressed. Coherent detection is presented as a means to extend the dispersion limit of a duobinary signal using an analog decision-directed phase-lock loop. Analytical bit-error ratio estimation for quadrature phase-shift keying signals is derived. To validate the promise for high spectral efficiency, the orthogonal-wavelength-division multiplexing scheme is suggested. In this scheme the WDM channels are spaced at the symbol rate, thus achieving the spectral efficiency limit. Theory, simulation and experimental results demonstrate the feasibility of this approach. Infinite impulse response filtering is shown to be an efficient alternative to finite impulse response filtering for chromatic dispersion compensation. Theory, design considerations, simulation and experimental results relating to this topic are presented. Interaction between fiber dispersion and nonlinearity remains the last major challenge

  4. Integration and alignment through mechanical measurements: the example of the ESPRESSO front-end units

    NASA Astrophysics Data System (ADS)

    Aliverti, Matteo; Pariani, Giorgio; Moschetti, Manuele; Riva, Marco

    2016-08-01

    Traditional techniques usually rely on optical feedback to align optical elements over all the degrees of freedom needed. This strongly iterative process implies the use of bulky and/or flexible adjustable mountings. Another solution under study consists in the characterization of every optomechanical elements and the integration of the parts without any optical feedback. The characterization can be performed using different 3D Coordinate Measuring Machines (like Laser Tracker, Articulated Arms and Cartesian ones) and referencing different parts like the optomechanical mounts or the optical surfaces. The alignment of the system is done adjusting the six degrees of freedom of every element with metallic shims. Those calibrated elements are used to correct the interfaces position of the semikinematic system composed by 3 screws and 3 pins. In this paper, the integration and alignment of the ESPRESSO Front End Units (FEUs) will be used as pathfinder to test different alignment methods and evaluate their performances.

  5. Develop techniques for ion implantation of PLZT for adaptive optics

    NASA Astrophysics Data System (ADS)

    Craig, R. A.; Batishko, C. R.; Brimhall, J. L.; Pawlewicz, W. T.; Stahl, K. A.

    1989-11-01

    Battelle Pacific Northwest Laboratory (PNL) conducted research into the preparation and characterization of ion-implanted adaptive optic elements based on lead-lanthanum-zirconate-titanate (PLZT). Over the 4-yr effort beginning FY 1985, the ability to increase the photosensitivity of PLZT and extend it to longer wavelengths was developed. The emphasis during the last two years was to develop a model to provide a basis for choosing implantation species and parameters. Experiments which probe the electronic structure were performed on virgin and implanted PLZT samples. Also performed were experiments designed to connect the developing conceptual model with the experimental results. The emphasis in FY 1988 was to extend the photosensitivity out to diode laser wavelengths. The experiments and modelling effort indicate that manganese will form appropriate intermediate energy states to achieve the longer wavelength photosensitivity. Preliminary experiments were also conducted to deposit thin film PLZT.

  6. Optical technique for measurement of random water wave surfaces

    NASA Technical Reports Server (NTRS)

    Sorrell, F. Y.; Withers, A. L.

    1976-01-01

    An optical system using the refraction of a vertical light ray has been developed for measuring the slope of random wind-generated water waves. The basic elements of the system are photovoltaic cells which are connected to individual amplifiers so that when the refracted light beam is incident on a cell, the output of the cell is amplified and then supplied as input to a comparator. The comparator then provides a specified voltage output, independent of the incident light intensity, as long as it is above a designated background value. The comparators are designed to give output voltages comparable with standard TTL. This arrangement provides a high signal from the cell when it experiences incident light, and a low signal when there is only background light, with the high and low signals at TTL voltage levels.

  7. Optical image encryption technique based on deterministic phase masks

    NASA Astrophysics Data System (ADS)

    Zamrani, Wiam; Ahouzi, Esmail; Lizana, Angel; Campos, Juan; Yzuel, María J.

    2016-10-01

    The double-random phase encoding (DRPE) scheme, which is based on a 4f optical correlator system, is considered as a reference for the optical encryption field. We propose a modification of the classical DRPE scheme based on the use of a class of structured phase masks, the deterministic phase masks. In particular, we propose to conduct the encryption process by using two deterministic phase masks, which are built from linear combinations of several subkeys. For the decryption step, the input image is retrieved by using the complex conjugate of the deterministic phase masks, which were set in the encryption process. This concept of structured masks gives rise to encryption-decryption keys which are smaller and more compact than those required in the classical DRPE. In addition, we show that our method significantly improves the tolerance of the DRPE method to shifts of the decrypting phase mask-when no shift is applied, it provides similar performance to the DRPE scheme in terms of encryption-decryption results. This enhanced tolerance to the shift, which is proven by providing numerical simulation results for grayscale and binary images, may relax the rigidity of an encryption-decryption experimental implementation setup. To evaluate the effectiveness of the described method, the mean-square-error and the peak signal-to-noise ratio between the input images and the recovered images are calculated. Different studies based on simulated data are also provided to highlight the suitability and robustness of the method when applied to the image encryption-decryption processes.

  8. Cleaning Verification Monitor Technique Based on Infrared Optical Methods

    DTIC Science & Technology

    2004-10-01

    Cleaning Verification Techniques.” Real-time methods to provide both qualitative and quantitative assessments of surface cleanliness are needed for a...detection VCPI method offer a wide range of complementary capabilities in real-time surface cleanliness verification. Introduction Currently...also has great potential to reduce or eliminate premature failures of surface coatings caused by a lack of surface cleanliness . Additional

  9. Orbit IMU alignment: Error analysis

    NASA Technical Reports Server (NTRS)

    Corson, R. W.

    1980-01-01

    A comprehensive accuracy analysis of orbit inertial measurement unit (IMU) alignments using the shuttle star trackers was completed and the results are presented. Monte Carlo techniques were used in a computer simulation of the IMU alignment hardware and software systems to: (1) determine the expected Space Transportation System 1 Flight (STS-1) manual mode IMU alignment accuracy; (2) investigate the accuracy of alignments in later shuttle flights when the automatic mode of star acquisition may be used; and (3) verify that an analytical model previously used for estimating the alignment error is a valid model. The analysis results do not differ significantly from expectations. The standard deviation in the IMU alignment error for STS-1 alignments was determined to the 68 arc seconds per axis. This corresponds to a 99.7% probability that the magnitude of the total alignment error is less than 258 arc seconds.

  10. Code division multiple-access techniques in optical fiber networks. II - Systems performance analysis

    NASA Astrophysics Data System (ADS)

    Salehi, Jawad A.; Brackett, Charles A.

    1989-08-01

    A technique based on optical orthogonal codes was presented by Salehi (1989) to establish a fiber-optic code-division multiple-access (FO-CDMA) communications system. The results are used to derive the bit error rate of the proposed FO-CDMA system as a function of data rate, code length, code weight, number of users, and receiver threshold. The performance characteristics for a variety of system parameters are discussed. A means of reducing the effective multiple-access interference signal by placing an optical hard-limiter at the front end of the desired optical correlator is presented. Performance calculations are shown for the FO-CDMA with an ideal optical hard-limiter, and it is shown that using a optical hard-limiter would, in general, improve system performance.

  11. Low voltage integrated optics electro-optical modulator applied to optical voltage transformer based on WLI technique

    NASA Astrophysics Data System (ADS)

    Santos, J. C.; Rubini, J.; Silva, L. P. C.; Caetano, R. E.

    2015-09-01

    The use of two electro-optical modulators linked in series, one for sensing and one for recovering signals, was formerly presented by some of the authors as a solution for interrogation of optical fiber sensor systems based on WLI method. A key feature required from such systems is that half-wave voltage (Vπ) of recovering modulator must be as small as possible. Aiming at meeting this requirement, in this paper it is presented the use of an unbalanced Michelson Interferometer implemented using an integrated optics component as recover interferometer in an optical voltage transformer intended for high voltage measurements.

  12. An optical technique to measure ion engine grid distortion due to differential thermal expansion

    NASA Technical Reports Server (NTRS)

    Trava-Airoldi, V. J.; Garner, C. E.; Pivirotto, T. J.; Brophy, J. R.

    1990-01-01

    This paper describes an optical technique developed for measuring small differential grid displacements due to thermal expansion of an ion thruster accelerator system. The technique is based on confocal scanning optical microscope type II. For the measurements of small displacements where there are distances on the order of a meter or more between the lens plane and the sample, some of the optical components are moved while the sample is kept fixed. The feasibility of applying this technique to measure the thermally induced ion thruster grid displacements was demonstrated in a bench-top simulation. It is noted that this technique can also provide information on grid movement resulting from thermal transients such as the start-up.

  13. A comparison of signal processing techniques for Intrinsic Optical Signal imaging in mice.

    PubMed

    Turley, Jordan A; Nilsson, Michael; Walker, Frederick Rohan; Johnson, Sarah J

    2015-01-01

    Intrinsic Optical Signal imaging is a technique which allows the visualisation and mapping of activity related changes within the brain with excellent spatial and temporal resolution. We analysed a variety of signal and image processing techniques applied to real mouse imaging data. The results were compared in an attempt to overcome the unique issues faced when performing the technique on mice and improve the understanding of post processing options available.

  14. MSE spectrograph optical design: a novel pupil slicing technique

    NASA Astrophysics Data System (ADS)

    Spanò, P.

    2014-07-01

    The Maunakea Spectroscopic Explorer shall be mainly devoted to perform deep, wide-field, spectroscopic surveys at spectral resolutions from ~2000 to ~20000, at visible and near-infrared wavelengths. Simultaneous spectral coverage at low resolution is required, while at high resolution only selected windows can be covered. Moreover, very high multiplexing (3200 objects) must be obtained at low resolution. At higher resolutions a decreased number of objects (~800) can be observed. To meet such high demanding requirements, a fiber-fed multi-object spectrograph concept has been designed by pupil-slicing the collimated beam, followed by multiple dispersive and camera optics. Different resolution modes are obtained by introducing anamorphic lenslets in front of the fiber arrays. The spectrograph is able to switch between three resolution modes (2000, 6500, 20000) by removing the anamorphic lenses and exchanging gratings. Camera lenses are fixed in place to increase stability. To enhance throughput, VPH first-order gratings has been preferred over echelle gratings. Moreover, throughput is kept high over all wavelength ranges by splitting light into more arms by dichroic beamsplitters and optimizing efficiency for each channel by proper selection of glass materials, coatings, and grating parameters.

  15. Comparative study of optical coherence tomography, photoacoustic technique, and time-of-flight technique in phantom measurements

    NASA Astrophysics Data System (ADS)

    Kinnunen, Matti; Myllylä, Risto

    2006-08-01

    of biomedical imaging techniques, the optical coherence tomography (OCT), photoacoustic (PA) and time-of-flight (TOF) techniques are among the most researched and, consequently, increasingly broadly applied. This article reviews their basic principles, compares their technical aspects and discusses their ability to determine optical parameters. Also studied is their applicability to non-invasive glucose monitoring in Intralipid TM phantom measurements, followed by a discussion of some detected problems. Although suffering from a limited probing depth, OCT was found to have the best capacity for detecting changes in the light scattering properties of Intralipid TM. Photon migration studies with the TOF technique showed changes in pulse amplitude, pulse width and arrival time of the pulse maximum as a function of changes in Intralipid TM concentration, whereas the sensitivity of the PA technique for detecting changes in scattering was less pronounced. However, each technique showed changes in the registered signals when measuring large glucose concentrations in Intralipid TM phantoms. Measurement results were also affected by the varying measurement geometries and the photon energies of the light sources.

  16. Novel x-ray optics for medical diagnostic techniques

    NASA Astrophysics Data System (ADS)

    Kuyumchyan, A.; Arvanian, V.; Kuyumchyan, D.; Aristov, V.; Shulakov, E.

    2009-08-01

    A new hard X - ray hologram with using crystal Fresnel zone plates (ZP) has been described. An image of Fourier hologram for hard X- ray is presented. X-ray phase contrast methods for medical diagnostics techniques are presented. We have developed an X-ray microscope, based on micro focus source which is capable of high resolution phasecontrast imaging and holograms. We propose a new imaging technique with the x-ray energy 8 keV. The method is expected to have wide applications in imaging of low absorbing samples such as biological and medical tissue. We used FIB to reproduction three dimension structures of damaged spinal cord of rat before and after combined treatment with NT3 and NR2D. PUBLISHER'S NOTE 12/16/09: This SPIE Proceedings paper has been updated with an erratum correcting several issues throughout the paper. The corrected paper was published in place of the earlier version on 9/1/2009. If you purchased the original version of the paper and no longer have access, please contact SPIE Digital Library Customer Service at CustomerService@SPIEDigitalLibrary.org for assistance.

  17. Alignment test results of the JWST Pathfinder Telescope mirrors in the cryogenic environment

    NASA Astrophysics Data System (ADS)

    Whitman, Tony L.; Wells, Conrad; Hadaway, James B.; Knight, J. Scott; Lunt, Sharon

    2016-07-01

    After integration of the Optical Telescope Element (OTE) to the Integrated Science Instrument Module (ISIM) to become the OTIS, the James Webb Space Telescope OTIS is tested at NASA's Johnson Space Center (JSC) in the cryogenic vacuum Chamber A for alignment and optical performance. The alignment of the mirrors comprises a sequence of steps as follows: The mirrors are coarsely aligned using photogrammetry cameras with reflective targets attached to the sides of the mirrors. Then a multi-wavelength interferometer is aligned to the 18-segment primary mirror using cameras at the center of curvature to align reflected light from the segments and using fiducials at the edge of the primary mirror. Once the interferometer is aligned, the 18 primary mirror segments are then adjusted to optimize wavefront error of the aggregate mirror. This process phases the piston and tilt positions of all the mirror segments. An optical fiber placed at the Cassegrain focus of the telescope then emits light towards the secondary mirror to create a collimated beam emitting from the primary mirror. Portions of the collimated beam are retro-reflected from flat mirrors at the top of the chamber to pass through the telescope to the Science Instrument (SI) detector. The image on the detector is used for fine alignment of the secondary mirror and a check of the primary mirror alignment using many of the same analysis techniques used in the on-orbit alignment. The entire process was practiced and evaluated in 2015 at cryogenic temperature with the Pathfinder telescope.

  18. Alignment Test Results of the JWST Pathfinder Telescope Mirrors in the Cryogenic Environment

    NASA Technical Reports Server (NTRS)

    Whitman, Tony L.; Wells, Conrad; Hadaway, James; Knight, J. Scott; Lunt, Sharon

    2016-01-01

    After integration of the Optical Telescope Element (OTE) to the Integrated Science Instrument Module (ISIM) to become the OTIS, the James Webb Space Telescope OTIS is tested at NASAs Johnson Space Center (JSC) in the cryogenic vacuum Chamber A for alignment and optical performance. The alignment of the mirrors comprises a sequence of steps as follows: The mirrors are coarsely aligned using photogrammetry cameras with reflective targets attached to the sides of the mirrors. Then a multi-wavelength interferometer is aligned to the 18-segment primary mirror using cameras at the center of curvature to align reflected light from the segments and using fiducials at the edge of the primary mirror. Once the interferometer is aligned, the 18 primary mirror segments are then adjusted to optimize wavefront error of the aggregate mirror. This process phases the piston and tilt positions of all the mirror segments. An optical fiber placed at the Cassegrain focus of the telescope then emits light towards the secondary mirror to create a collimated beam emitting from the primary mirror. Portions of the collimated beam are retro-reflected from flat mirrors at the top of the chamber to pass through the telescope to the SI detector. The image on the detector is used for fine alignment of the secondary mirror and a check of the primary mirror alignment using many of the same analysis techniques used in the on-orbit alignment. The entire process was practiced and evaluated in 2015 at cryogenic temperature with the Pathfinder telescope.

  19. Pupil Alignment Considerations for Large, Deployable Space Telescopes

    NASA Technical Reports Server (NTRS)

    Bos, Brent J.; Ohl, Raymond G.; Kubalak, Daivd A.

    2011-01-01

    For many optical systems the properties and alignment of the internal apertures and pupils are not critical or controlled with high precision during optical system design, fabrication or assembly. In wide angle imaging systems, for instance, the entrance pupil position and orientation is typically unconstrained and varies over the system s field of view in order to optimize image quality. Aperture tolerances usually do not receive the same amount of scrutiny as optical surface aberrations or throughput characteristics because performance degradation is typically graceful with misalignment, generally only causing a slight reduction in system sensitivity due to vignetting. But for a large deployable space-based observatory like the James Webb Space Telescope (JWST), we have found that pupil alignment is a key parameter. For in addition to vignetting, JWST pupil errors cause uncertainty in the wavefront sensing process that is used to construct the observatory on-orbit. Furthermore they also open stray light paths that degrade the science return from some of the telescope s instrument channels. In response to these consequences, we have developed several pupil measurement techniques for the cryogenic vacuum test where JWST science instrument pupil alignment is verified. These approaches use pupil alignment references within the JWST science instruments; pupil imaging lenses in three science instrument channels; and unique pupil characterization features in the optical test equipment. This will allow us to verify and crosscheck the lateral pupil alignment of the JWST science instruments to approximately 1-2% of their pupil diameters.

  20. Simple, generalizable route to highly aligned block copolymer thin films

    NASA Astrophysics Data System (ADS)

    Qiang, Zhe; Cavicchi, Kevin; Vogt, Bryan; University of Akron Team

    Macroscopic alignment of block copolymer domains in thin films is desired for many applications, such as cell responsive surfaces or optical polarizers. Alignment generally requires specialized tools that apply external fields, shear force gradient, or produce topological patterned substrates. This requirement limits the broad academic application of aligned BCPs. Here, we describe a simple modification of commonly utilized solvent vapor annealing (SVA) process for macroscopic alignment of BCPs. Adhering a flat, crosslinked elastomer pad to the BCP film leads to differential swelling between the elastomer pad and BCP to produce a shear force that aligns the ordered BCP domains. The role of elastomer properties, solvent quality, drying rate and degree of segregation of the block copolymer will be discussed to provide generalized rules for alignment with this technique. Cylindrical nanostructures formed in polystyrene-block-polydimethylsiloxane can be transformed into arrays of silica lines and increasing the thickness from a monolayer to bilayer can effectively halve the spacing of the lines. These results illustrate a generalized method for BCP alignment and a potential route for the generation of complex hierarchical assembled structures. A generalized method for block copolymer thin film alignment: solvent vapor annealing with shear.

  1. Interferometric and nonlinear-optical spectral-imaging techniques for outer space and live cells

    NASA Astrophysics Data System (ADS)

    Itoh, Kazuyoshi

    2015-12-01

    Multidimensional signals such as the spectral images allow us to have deeper insights into the natures of objects. In this paper the spectral imaging techniques that are based on optical interferometry and nonlinear optics are presented. The interferometric imaging technique is based on the unified theory of Van Cittert-Zernike and Wiener-Khintchine theorems and allows us to retrieve a spectral image of an object in the far zone from the 3D spatial coherence function. The retrieval principle is explained using a very simple object. The promising applications to space interferometers for astronomy that are currently in progress will also be briefly touched on. An interesting extension of interferometric spectral imaging is a 3D and spectral imaging technique that records 4D information of objects where the 3D and spectral information is retrieved from the cross-spectral density function of optical field. The 3D imaging is realized via the numerical inverse propagation of the cross-spectral density. A few techniques suggested recently are introduced. The nonlinear optical technique that utilizes stimulated Raman scattering (SRS) for spectral imaging of biomedical targets is presented lastly. The strong signals of SRS permit us to get vibrational information of molecules in the live cell or tissue in real time. The vibrational information of unstained or unlabeled molecules is crucial especially for medical applications. The 3D information due to the optical nonlinearity is also the attractive feature of SRS spectral microscopy.

  2. Differential deposition technique for figure corrections in grazing-incidence x-ray optics

    NASA Astrophysics Data System (ADS)

    Kilaru, Kiranmayee; Ramsey, Brian D.; Gubarev, Mikhail V.; Gregory, Don A.

    2011-10-01

    A differential deposition technique was investigated as a way to minimize axial figure errors in full-shell, grazing-incidence, reflective x-ray optics. These types of optics use a combination of off-axis conic segments--hyperbolic, parabolic, and/or elliptical, to reflect and image x-rays. Several such mirrors or ``shells'' of decreasing diameter are typically concentrically nested to form a single focusing unit. Individual mirrors are currently produced at Marshall Space Flight Center using an electroforming technique, in which the shells are replicated off figured and superpolished mandrels. Several factors in this fabrication process lead to low- and mid-spatial frequency deviations in the surface profile of the shell that degrade the imaging quality of the optics. A differential deposition technique, discussed in this paper, seeks to improve the achievable resolution of the optics by correcting the surface profile deviations of the shells after fabrication. As a proof of concept, the technique was implemented on small-animal radionuclide-imaging x-ray optics being considered for medical applications. This paper discusses the deposition technique, its implementation, and the experimental results obtained to date.

  3. Two-Wavelength Optical-Path-Difference Mapping

    NASA Technical Reports Server (NTRS)

    Manhart, Paul K.

    1990-01-01

    Proposed technique for measuring shapes and alignments of reflectors based on use of two-wavelength absolute-distance interferometer to generate optical-path-difference maps of reflecting or refracting surfaces. Facilitates such tasks as determining manufacturing and alignment errors of off-axis segment of large-aperture paraboloidal telescope mirror, or aligning all segments of such mirror. Suitable for use where reflecting surfaces highly aspherical, initial misalignments large, and/or surface errors exceed optical wavelengths.

  4. Direct evaluation of anisotropic carrier mobility in uniaxially aligned polymer semiconductor film by time-resolved microscopic optical second-harmonic generation measurement

    NASA Astrophysics Data System (ADS)

    Abe, Kentaro; Manaka, Takaaki; Iwamoto, Mitsumasa

    2017-01-01

    Mobility anisotropy in uniaxially-aligned fluorene co-polymer thin film was directly observed by using time-resolved microscopic optical second-harmonic generation (TRM-SHG) imaging. Main-chain orientation of fluorene co-polymer was determined by polarized absorption measurement, and the mobilities in the direction parallel and perpendicular to the main-chain were respectively estimated as 4.8× {{10}-3} cm2 Vs-1 and 1.2× {{10}-3} cm2 Vs-1 from the visualized carrier motion starting from a round-shape electrode. These results indicate that the mobility anisotropy of this sample was 4.0. Activation energy for each direction was also evaluated by the temperature dependence measurement as 117 and 94 meV, respectively. The TRM-SHG method enables us to estimate mobility and activation energy of the oriented polymer film in all directions at once.

  5. Optical techniques for industrial inspection; Proceedings of the Meeting, Quebec, Canada, June 4-6, 1986

    SciTech Connect

    Cielo, P.G.

    1986-01-01

    Papers on optical inspection in industry; hot-slab surface inspection by the laser scanning method; surface inspection based on stochastic modeling; a semiconductor processing technique based on Faraday rotation measurements using a CO/sub 2/ laser; an intelligent vision controller for circuits card lead inspection; and noncontacting optical measurement and inspection systems are presented. Topics discussed include optical sensing techniques for three-dimensional machine vision; the performance analysis of a three-dimensional sensor based on time-of-flight measurements; triangulation with large dynamical range; and recognition for three-dimensional surface shape using multiple distance features. Consideration is given to Raman spectroscopy applied to polymer analysis; an optical approach to the measurement of the lignin content of kraft pulps and of delignification in kraft pulping; diagnostics from imaging inside gas turbine combustors; and environmental-noise analysis in active-vision systems for adaptive welding.

  6. Nonconventional optical techniques for optical-wavefront processing. Final report, June 1985-July 1986

    SciTech Connect

    Salour, M.M.

    1987-06-01

    This report describes the design and construction of an optically pumped semiconductor laser oscillator with the following specifications: 1) Operating wavelengths, 414 nm and 680nm, interchangeable (i.e., requires a change in optical setup and the pump source, but no change in the cavity design); 2) CW power, nominal 30 mW each line; and 3) Tuning range of + or - 30 nm. The laser includes all external ring-cavity components, cooling (nonliquid N2), and provisions were made for mounting line narrowing and tuning elements. Ancillary equipment list, operating and instruction manuals were also provided.

  7. Burst-mode gain switched technique for high peak and average optical energy extraction.

    PubMed

    Nikumb, S K; Seguin, H J; Seguin, V A; Willis, R J; Cheng, Z; Reshef, H

    1989-05-01

    The optical performance of a cw PIE CO(2) laser has been substantially improved through the adoption of a burst-mode gain switching technique. The approach has provided a doubling of the average beam power extractable from the device. With appropriate optimization, the process could possibly permit the attainment of pulsed energy extraction in the kilohertz range, and with average optical powers within the several tens of kilowatt category.

  8. Comment on: Computation of the optical trapping force using an FDTD based technique.

    PubMed

    Zhou, Fei; Gan, Xiaosong; Xu, Wendong; Gan, Fuxi

    2006-12-11

    In this comment, problems associated with an oversimplified FDTD based model used for trapping force calculation in recent papers "Computation of the optical trapping force using an FDTD based technique" [Opt. Express 13, 3707 (2005)], and "Rigorous time domain simulation of momentum transfer between light and microscopic particles in optical trapping" [Opt. Express 12, 2220 (2004)] are discussed. A more rigorous model using in Poynting vector is also presented.

  9. Optical and imaging techniques for in-vivo sunscreens investigation

    NASA Astrophysics Data System (ADS)

    Utz, Sergei R.; Knuschke, Peter; Sinichkin, Yuri P.

    1996-01-01

    The methods available for testing the efficacy of topical sunscreens have improved considerably in recent years. Nevertheless, so far no simple and rapid test has been proposed to measure in vivo transmission spectra of sunscreens in the UVA region. Spectral changes that occur after sunscreen application were measured with a fluorescence spectrometer (LS 50B, Perkin Elmer, UK) equipped with a Y-shape quartz guide for in vivo measurements. Three sunscreens with different protection factors in the UVA range were tested. The excitation-emission maps of human collagen, skin, and sunscreens were analyzed. Visual demonstrations of the protective effects of sunscreens were also performed with photo- and video imaging techniques. As a consequence of the human skin and sunscreen's fluorescence map analysis, the optimal spectral regions (both for direct and indirect fluorescence measurements) were detected. In vivo fluorescence and remittance spectroscopy were used to investigate the time dependence in transmission spectra of epidermis with applied sunscreens. We also evaluate the feasibility of in vivo fluorescence measurements for the investigation of the sunscreen's water-resistance. The procedure is simple, and values obtained can be used to predict UVA protection on the basis of the mathematical algorithms.

  10. Computation of the optical trapping force using an FDTD based technique.

    PubMed

    Gauthier, Robert

    2005-05-16

    The computation details related to computing the optical radiation pressure force on various objects using a 2-D grid FDTD algorithm are presented. The technique is based on propagating the electric and magnetic fields through the grid and determining the changes in the optical energy flow with and without the trap object(s) in the system. Traces displayed indicate that the optical forces and FDTD predicted object behavior are in agreement with published experiments and also determined through other computation techniques. We show computation results for a high and low dielectric disc and thin walled shell. The FDTD technique for computing the light-particle force interaction may be employed in all regimes relating particle dimensions to source wavelength. The algorithm presented here can be easily extended to 3-D and include torque computation algorithms, thus providing a highly flexible and universally useable computation engine.

  11. Magneto-optical imaging technique for hostile environments: The ghost imaging approach

    SciTech Connect

    Meda, A.; Caprile, A.; Avella, A.; Ruo Berchera, I.; Degiovanni, I. P.; Magni, A.; Genovese, M.

    2015-06-29

    In this paper, we develop an approach to magneto optical imaging (MOI), applying a ghost imaging (GI) protocol to perform Faraday microscopy. MOI is of the utmost importance for the investigation of magnetic properties of material samples, through Weiss domains shape, dimension and dynamics analysis. Nevertheless, in some extreme conditions such as cryogenic temperatures or high magnetic field applications, there exists a lack of domain images due to the difficulty in creating an efficient imaging system in such environments. Here, we present an innovative MOI technique that separates the imaging optical path from the one illuminating the object. The technique is based on thermal light GI and exploits correlations between light beams to retrieve the image of magnetic domains. As a proof of principle, the proposed technique is applied to the Faraday magneto-optical observation of the remanence domain structure of an yttrium iron garnet sample.

  12. Magneto-optical imaging technique for hostile environments: The ghost imaging approach

    NASA Astrophysics Data System (ADS)

    Meda, A.; Caprile, A.; Avella, A.; Ruo Berchera, I.; Degiovanni, I. P.; Magni, A.; Genovese, M.

    2015-06-01

    In this paper, we develop an approach to magneto optical imaging (MOI), applying a ghost imaging (GI) protocol to perform Faraday microscopy. MOI is of the utmost importance for the investigation of magnetic properties of material samples, through Weiss domains shape, dimension and dynamics analysis. Nevertheless, in some extreme conditions such as cryogenic temperatures or high magnetic field applications, there exists a lack of domain images due to the difficulty in creating an efficient imaging system in such environments. Here, we present an innovative MOI technique that separates the imaging optical path from the one illuminating the object. The technique is based on thermal light GI and exploits correlations between light beams to retrieve the image of magnetic domains. As a proof of principle, the proposed technique is applied to the Faraday magneto-optical observation of the remanence domain structure of an yttrium iron garnet sample.

  13. New optical gating technique for detection of electric field waveforms with subpicosecond resolution

    NASA Astrophysics Data System (ADS)

    Muraviev, Andrey; Gutin, Alexey; Rupper, Greg; Rudin, Sergey; Shen, Xiaohan; Yamaguchi, Masashi; Aizin, Gregory; Shur, Michael

    2016-06-01

    We report on the new optical gating technique used for the direct photoconductive detection of short pulses of terahertz radiation with the resolution up to 250 femtoseconds. The femtosecond optical laser pulse time delayed with respect to the THz pulse generated a large concentration of the electron hole pairs in the AlGaAs/InGaAs High Electron Mobility Transistor (HEMT) drastically increasing the conductivity on the femtosecond scale and effectively shorting the source and drain. This optical gating quenched the response of the plasma waves launched by the THz pulse and allowed us to reproduce the waveform of the THz pulse by varying the time delay between the THz and quenching optical pulses. The results are in excellent agreement with the electro-optic effect measurements and with our hydrodynamic model that predicts the ultra-fast transistor plasmonic response at the time scale much shorter than the electron transit time, in full agreement with the measured data.

  14. From superresolution to nanodetection: overview of far field optical nanoscopy techniques for nanostructures

    NASA Astrophysics Data System (ADS)

    Montgomery, P. C.; Leong-Hoi, A.; Anstotz, F.; Mitev, D.; Pramatarova, L.; Haeberlé, O.

    2016-02-01

    Far field optical nanoscopy has been brought to the forefront with the 2014 Nobel Prize for chemistry in fluorescent nanoscopy for revealing intra-cellular details of tens of nm. In this review, we present an improved classification scheme that summarizes the many optical nanoscopy techniques that exist. We place particular emphasis on unlabelledsuperresolution techniques that provide real improved resolving power and unlabellednanodetection techniques for characterizing unresolved nanostructures. Superresolution is illustrated with sub-100 nm imaging of diatoms with tomographic diffractive microscopyand adenoviruseswith submerged microsphere optical nanoscopy. Three sub-categories of nanodetectionare then presented. Contrast enhancement is illustrated with surface enhanced ellipsometric contrast microscopy for the study of bacterial motility and strobed phase contrast microscopy for measuring the mechanical properties of vesicle membranes. High sensitivity phase measurement using interference microscopy demonstrates how nanostructured surfaces and structures can be characterized in biomaterials, laser textured stainless steel and defects within thin polymer films. Finally, deconvolution is illustrated with the use of through-focus scanning optical microscopy in critical dimension measurement and characterization of 40 nm linewidths in microelectronic devices. In this way we show how new far field optical nanoscopy techniques are being developed for unlabelled characterization of nano and biomaterials.

  15. Strategies for active alignment of lenses

    NASA Astrophysics Data System (ADS)

    Langehanenberg, Patrik; Heinisch, Josef; Wilde, Chrisitan; Hahne, Felix; Lüerß, Bernd

    2015-10-01

    Today's optical systems require up-to-date assembly and joining technology. The trend of keeping dimensions as small as possible while maintaining or increasing optical imaging performance leaves little to no room for mechanical lens adjustment equipment that may remain in the final product. In this context active alignment of optical elements opens up possibilities for the fast and cost-economic manufacturing of lenses and lens assemblies with highest optical performance. Active alignment for lens manufacturing is the precise alignment of the optical axis of a lens with respect to an optical or mechanical reference axis (e.g. housing) including subsequent fixation by glue. In this contribution we will describe different approaches for active alignment and outline strengths and limitations of the different methods. Using the SmartAlign principle, highest quality cemented lenses can be manufactured without the need for high precision prealignment, while the reduction to a single alignment step greatly reduces the cycle time. The same strategies can also be applied to bonding processes. Lenses and lens groups can be aligned to both mechanical and optical axes to maximize the optical performance of a given assembly. In hybrid assemblies using both mechanical tolerances and active alignment, SmartAlign can be used to align critical lens elements anywhere inside the system for optimized total performance. Since all geometrical parameters are re-measured before each alignment, this process is especially suited for complex and time-consuming production processes where the stability of the reference axis would otherwise be critical. For highest performance, lenses can be actively aligned using up to five degrees of freedom. In this way, SmartAlign enables the production of ultra-precise mounted lenses with an alignment precision below 1 μm.

  16. Film fabrication of Fe or Fe3O4 nanoparticles mixed with palmitic acid for vertically aligned carbon nanotube growth using Langmuir-Blodgett technique

    NASA Astrophysics Data System (ADS)

    Nakamura, Kentaro; Kuriyama, Naoki; Takagiwa, Shota; Sato, Taiga; Kushida, Masahito

    2016-03-01

    Vertically aligned carbon nanotubes (VA-CNTs) were studied as a new catalyst support for polymer electrolyte fuel cells (PEFCs). Controlling the number density and the diameter of VA-CNTs may be necessary to optimize PEFC performance. As the catalyst for CNT growth, we fabricated Fe or Fe3O4 nanoparticle (NP) films by the Langmuir-Blodgett (LB) technique. The catalyst Fe or Fe3O4 NPs were widely separated by mixing with filler molecules [palmitic acid (C16)]. The number density of VA-CNTs was controlled by varying the ratio of catalyst NPs to C16 filler molecules. The VA-CNTs were synthesized from the catalyst NP-C16 LB films by thermal chemical vapor deposition (CVD) using acetylene gas as the carbon source. The developing solvents used in the LB technique and the hydrogen reduction conditions of CVD were optimized to improve the VA-CNT growth rate. We demonstrate that the proposed method can independently control both the density and the diameter of VA-CNTs.

  17. Cerebral blood flow and autoregulation: current measurement techniques and prospects for noninvasive optical methods.

    PubMed

    Fantini, Sergio; Sassaroli, Angelo; Tgavalekos, Kristen T; Kornbluth, Joshua

    2016-07-01

    Cerebral blood flow (CBF) and cerebral autoregulation (CA) are critically important to maintain proper brain perfusion and supply the brain with the necessary oxygen and energy substrates. Adequate brain perfusion is required to support normal brain function, to achieve successful aging, and to navigate acute and chronic medical conditions. We review the general principles of CBF measurements and the current techniques to measure CBF based on direct intravascular measurements, nuclear medicine, X-ray imaging, magnetic resonance imaging, ultrasound techniques, thermal diffusion, and optical methods. We also review techniques for arterial blood pressure measurements as well as theoretical and experimental methods for the assessment of CA, including recent approaches based on optical techniques. The assessment of cerebral perfusion in the clinical practice is also presented. The comprehensive description of principles, methods, and clinical requirements of CBF and CA measurements highlights the potentially important role that noninvasive optical methods can play in the assessment of neurovascular health. In fact, optical techniques have the ability to provide a noninvasive, quantitative, and continuous monitor of CBF and autoregulation.

  18. Onorbit IMU alignment error budget

    NASA Technical Reports Server (NTRS)

    Corson, R. W.

    1980-01-01

    The Star Tracker, Crew Optical Alignment Sight (COAS), and Inertial Measurement Unit (IMU) from a complex navigation system with a multitude of error sources were combined. A complete list of the system errors is presented. The errors were combined in a rational way to yield an estimate of the IMU alignment accuracy for STS-1. The expected standard deviation in the IMU alignment error for STS-1 type alignments was determined to be 72 arc seconds per axis for star tracker alignments and 188 arc seconds per axis for COAS alignments. These estimates are based on current knowledge of the star tracker, COAS, IMU, and navigation base error specifications, and were partially verified by preliminary Monte Carlo analysis.

  19. Optical upconversion techniques for high-sensitivity millimetre-wave detection

    NASA Astrophysics Data System (ADS)

    Schuetz, Christopher A.; Prather, Dennis W.

    2004-12-01

    Millimeter-wave radiation has the unique ability to penetrate atmospheric obscurations such as smoke, fog, and light rain while maintaining the capability for high-resolution imaging. However, suitable technologies for creating high-sensitivity, large pixel-count detectors are a limiting factor in the implementation of such systems. To this end, we present a technique for detecting millimeter-wave radiation based on optical upconversion that promises both high sensitivity and scalability to large pixel arrays. High-speed optical modulation is used to transfer millimeter-wave radiation onto the sidebands of a near-infrared optical carrier frequency. Optical filtering techniques are subsequently used to suppress light at the carrier frequency. The resultant signal is passed to a low-frequency photodetector, which converts the remaining sideband energy to a photocurrent proportional to the incident millimeter wave energy at the modulator input. Utilizing the low noise powers of such photodetectors, high sensitivities may be obtained even accounting for the relatively high signal losses associated with optical upconversion. Since optical upconversion inherently preserves both phase and amplitude information and fiber optics may readily be used for low-loss routing of the modulated signal, such an approach offers promise for high-resolution synthetic aperture imaging. Alternatively, since each of the required components may be fabricated in III-V materials using planar semiconductor processing techniques, integration of multi-pixel arrays is feasible. Herein, we present experimental results obtained using a baseline detector assembled from commercially available fiber-optic components as well as efforts to integrate the desired functionality into a single GaAs substrate. An initial noise equivalent power (NEP) of the proposed detector has been demonstrated at sub-nanowatt levels, with improvements to sub-picowatt NEP's anticipated as the setup is optimized.

  20. Alignment mechanism of liquid crystal in a stretched porous polymer film

    NASA Astrophysics Data System (ADS)

    Fujikake, Hideo; Kuboki, Masashi; Murashige, Takeshi; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro

    2003-09-01

    This article discusses the mechanism of nematic liquid crystal alignment in stretched porous polymer films. The polymer films were formed by extreme stretching of an isotropic porous polyolefin, such that the draw ratio was 12:1. A 6-μm-thick porous film with a high porosity coefficient of 92% revealed fine string-shaped areas that exhibited optical anisotropy due to their possessing a high degree of molecular alignment. The porous film was filled with nematic liquid crystal and then the composite film was sandwiched between transparent electrodes coated onto glass substrates, without the use of conventional alignment layers. From polarizing microscopy observations it was found that the string-like polymer areas induce liquid crystal molecular alignment. The liquid crystal cells can exhibit an electrically controlled birefringence effect. This alignment technique enables us to realize three-dimensional control of liquid crystal alignment.

  1. Surface alignment, anchoring transitions, optical properties, and topological defects in the nematic phase of thermotropic bent-core liquid crystal A131

    NASA Astrophysics Data System (ADS)

    Senyuk, B.; Wonderly, H.; Mathews, M.; Li, Q.; Shiyanovskii, S. V.; Lavrentovich, O. D.

    2010-10-01

    We study optical, structural, and surface anchoring properties of thermotropic nematic bent-core material A131. The focus is on the features associated with orientational order as the material has been reported to exhibit not only the usual uniaxial nematic but also the biaxial nematic phase. We demonstrate that A131 experiences a surface anchoring transition from a perpendicular to tilted alignment when the temperature decreases. The features of the tilted state are consistent with surface-induced birefringence associated with smectic layering near the surface and a molecular tilt that changes along the normal to the substrates. The surface-induced birefringence is reduced to zero by a modest electric field that establishes a uniform uniaxial nematic state. Both refractive and absorptive optical properties of A131 are consistent with the uniaxial order. We found no evidence of the “polycrystalline” biaxial behavior in the cells placed in crossed electric and magnetic fields. We observe stable topological point defects (boojums and hedgehogs) and nonsingular “escaped” disclinations pertinent only to the uniaxial order. Finally, freely suspended films of A131 show uniaxial nematic and smectic textures; a decrease in the film thickness expands the temperature range of stability of smectic textures, supporting the idea of surface-induced smectic layering. Our conclusion is that A131 features only a uniaxial nematic phase and that the apparent biaxiality is caused by subtle surface effects rather than by the bulk biaxial phase.

  2. Combined laser calorimetry and photothermal technique for absorption measurement of optical coatings

    SciTech Connect

    Li Bincheng; Blaschke, Holger; Ristau, Detlev

    2006-08-10

    To the best of our knowledge, a combined sensitive technique employing both laser calorimetry and a surface thermal lens scheme for measuring absorption values of optical coatings is presented for the first time. Laser calorimetric and pulsed surface thermal lens signals are simultaneously obtained with a highly reflecting UV coating sample irradiated at 193 nm. The advantages and potential applications of the combined technique and the experimental factors limiting the measurement sensitivity are discussed.

  3. Combined laser calorimetry and photothermal technique for absorption measurement of optical coatings.

    PubMed

    Li, Bincheng; Blaschke, Holger; Ristau, Detlev

    2006-08-10

    To the best of our knowledge, a combined sensitive technique employing both laser calorimetry and a surface thermal lens scheme for measuring absorption values of optical coatings is presented for the first time. Laser calorimetric and pulsed surface thermal lens signals are simultaneously obtained with a highly reflecting UV coating sample irradiated at 193 nm. The advantages and potential applications of the combined technique and the experimental factors limiting the measurement sensitivity are discussed.

  4. Pairwise Sequence Alignment Library

    SciTech Connect

    Jeff Daily, PNNL

    2015-05-20

    Vector extensions, such as SSE, have been part of the x86 CPU since the 1990s, with applications in graphics, signal processing, and scientific applications. Although many algorithms and applications can naturally benefit from automatic vectorization techniques, there are still many that are difficult to vectorize due to their dependence on irregular data structures, dense branch operations, or data dependencies. Sequence alignment, one of the most widely used operations in bioinformatics workflows, has a computational footprint that features complex data dependencies. The trend of widening vector registers adversely affects the state-of-the-art sequence alignment algorithm based on striped data layouts. Therefore, a novel SIMD implementation of a parallel scan-based sequence alignment algorithm that can better exploit wider SIMD units was implemented as part of the Parallel Sequence Alignment Library (parasail). Parasail features: Reference implementations of all known vectorized sequence alignment approaches. Implementations of Smith Waterman (SW), semi-global (SG), and Needleman Wunsch (NW) sequence alignment algorithms. Implementations across all modern CPU instruction sets including AVX2 and KNC. Language interfaces for C/C++ and Python.

  5. In situ Optical Monitoring of Vertically-Aligned Multiwall Carbon Nanotube Array Growth During Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Puretzky, Alex A.; Geohegan, David B.; Howe, Jane; Ivanov, Ilia N.; Jesse, Stephen; Eres, Gyula

    2004-03-01

    A detailed experimental study of vertically aligned arrays of multi-wall carbon nanotubes (VAA-MWNT) growth by chemical vapor deposition (CVD) based on time-resolved reflectivity (TRR) as a diagnostic to measure and control the length of VAA-MWNTs in situ is performed. Attenuation of a reflected HeNe laser beam and Fabry-Perot fringes are used to measure the length of VAA-MWNT arrays throughout the first 10 microns of growth, providing in situ growth rates and permitting the kinetics and termination of growth to be studied. VAA-MWNT growth was investigated between 530 C and 900 C on Si substrates with evaporated Al/Fe/Mo multiplayer catalysts and acetylene feedstock. It was demonstrated that the growth terminates rapidly at a relatively low (535-600 C) and high (800-900 C) temperatures, showing a relatively narrow temperature window for optimal growth of long VAA-MWNTs (up to 2-4 mm) around 700 C, at a growth rate of about 0.2 - 0.3 microns/s. Nanotube lengths were controlled by rapid evacuation of the chamber. The extinction coefficients of the VAA-MWNTs were studied and correlated with nanotube wall structures. It was demonstrated that decreasing the partial pressure of the C2H2 gas could increase the growth termination length. A simple kinetic model was considered to explain the observed growth kinetics and to discuss the main processes responsible for the growth of VAA-MWNTs. The authors gratefully acknowledge the funding support from DARPA-DSO, NASA-Langley Research Center, and the U.S. Department of Energy under contract DE-AC05-00OR22725 with the Oak Ridge National Laboratory, managed by UT-Battelle, LLC and the Laboratory-Directed Research and Development Program at ORNL.

  6. Application of diffusion and photosensitizing techniques in PMMA to optical interconnects

    NASA Astrophysics Data System (ADS)

    Brenner, Karl-Heinz; Kufner, Maria; Kufner, Stefan; Sinzinger, Stefan; Testorf, Markus E.

    1990-07-01

    A new technique for the three dimensional integration of optical components is presented. It is based on diffusion techniques and photoinitiated polymerization. Initial experimental results demonstrate the feasibility and efficiency. DIFFUSION jQ PHOTOINITIATED POLYMERISA11ON We want to combine diffusion with photoinitiated polymerization in order to form passive elements which are necessary for three dimensional integration of optical components for microoptical systems1''2. The production of optical elements by photopolymerization consists of two main steps. First the PMMA is sensitized to ultraviolet light by diffusing a photoinitiator into the substrat. Then the exposure by UV light causes an increase in the thickness and in the refractive index. The structuring can be achieved either by local diffusion and global exposure for stabilization or by global diffusion and local exposure. In the first case metal-masks for the diffusion process are necessary whereas in the second case photo-masks can be used. OPTICAL INTERCONNECFION For realizing a flexible optical interconnection plate3''4 the necessary functions are: light collimation light deflection and beam splitting. Collimation can be achieved by microlenses. For deflection we use a miniaturized prism. For beam splitting an index grating can be used. The components are integrated within a planar PMMA plate. EXPERIMENTAL RESULTS By measuring the phase profile of diffused lenses and prisms we demonstrated that phase shifts of several wavelengths can be achieved by polymerization and diffusion techniques. The main effect results from the

  7. Optical techniques for signal distribution and control in advanced radar and communication systems

    NASA Astrophysics Data System (ADS)

    Forrest, J. R.

    1985-03-01

    It is concluded that optical techniques offer some advantages for signal distribution and control in advanced radar and communication systems. They are clearly ideal for transporting microwave signals over considerable distances, as in remote positioning of radar receivers, provided high dynamic range is not required and an enclosed transmission path is essential. They are an elegant means of distributing low level r.f. or i.f. signals around an active phased array where these signals are of relatively constant amplitude (as in mixer local oscillator applications). However, there is currently a rather restrictive limit on the size of distribution network possible. Optical techniques are obviously suitable for distributing digital control signals to phased array modules and confer considerable immunity to interference. They are less suitable for high dynamic range signals, such as the received radar returns, either at r.f. or when downcovered to i.f. Future developments in coherent optics or in fast optical A/D technology could, however, influence this conclusion. Currently, the optimum applications for optical techniques appear to be i.f. beamformers for multibeam communication satellite systems and in calibration/monitoring systems for phased arrays.

  8. Overview of label-free far field optical nanoscopy techniques for nanometrology

    NASA Astrophysics Data System (ADS)

    Montgomery, Paul; Leong-Hoï, Audrey; Anstotz, Freddy; Liu, Hui; Simon, Bertrand; Debailleul, Matthieu; Haeberlé, Olivier

    2016-04-01

    The development of new nanomaterials, devices and systems is very much dependent on the availability of new techniques for nanometrology. There now exists many advanced optical imaging techniques capable of subwavelength resolution and detection, recently brought to the forefront through the 2014 Nobel Prize for chemistry for fluorescent STED and single molecule microscopy. Label-free nanoscopy techniques are particularly interesting for nanometrology since they have the advantages of being less intrusive and open to a wider number of structures that can be observed compared with fluorescent techniques. In view of the existence of many nanoscopy techniques, we present a practical classification scheme to help in their understanding. An important distinction is made between superresolution techniques that provide resolutions better than the classical λ/2 limit of diffraction and nanodetection techniques that are used to detect or characterize unresolved nanostructures or as nanoprobes to image sub-diffraction nanostructures. We then highlight some of the more important label-free techniques that can be used for nanometrology. Superresolution techniques displaying sub-100 nm resolution are demonstrated with tomographic diffractive microscopy (TDM) and submerged microsphere optical nanoscopy (SMON). Nanodetection techniques are separated into three categories depending on whether they use contrast, phase or deconvolution. The use of increased contrast is illustrated with ellipsometric contrast microscopy (SEEC) for measuring nanostructures. Very high sensitivity phase measurement using interference microscopy is then shown for characterizing nanometric surface roughness or internal structures. Finally, the use of through-focus scanning optical microscopy (TSOM) demonstrates the measurement and characterization of 60 nm linewidths in microelectronic devices.

  9. Preparation and characterization WDM technique for linear disturbance localization in fibre optical sensor

    NASA Astrophysics Data System (ADS)

    Życzkowski, M.; Ciurapinski, W.; Szustakowski, M.

    2007-10-01

    Ordinary perimeter security systems consist of many individual sensors with detection range 200-300 meters. These limitations are connected with physical phenomena that are used in microwave and infrared barriers as well as in ground and fence cable sensors. On the contrary, fiber optic perimeter sensors can be applied in the range of many kilometers and zone length 200-300 meters is degradation of their possibilities. This paper presents investigation results of a new generation of the fiber optic perimeter sensor using WDM technique. These systems can detect a potential intruder and determine its position along a protected zone. The work presents a method of linear localization of disturbance point in the two-interferometer and modalmertic fiber optic sensors in one optical fiber. These sensors are in one fiber optic cable with two- interferometers (Sagnac) and in transmissive configuration. Using WDM technique makes it possible to obtain new technical properties that can broaden effectiveness and scope of application. Arrangement of a laboratory model of the sensors and its signal processing scheme is presented. During research of a laboratory model, it was possible to detect the position of the disturbance in one optical fiber with resolution of about 50m along a 10-km long sensor.

  10. Ultrabroadband phased-array radio frequency (RF) receivers based on optical techniques

    NASA Astrophysics Data System (ADS)

    Overmiller, Brock M.; Schuetz, Christopher A.; Schneider, Garrett; Murakowski, Janusz; Prather, Dennis W.

    2014-03-01

    Military operations require the ability to locate and identify electronic emissions in the battlefield environment. However, recent developments in radio detection and ranging (RADAR) and communications technology are making it harder to effectively identify such emissions. Phased array systems aid in discriminating emitters in the scene by virtue of their relatively high-gain beam steering and nulling capabilities. For the purpose of locating emitters, we present an approach realize a broadband receiver based on optical processing techniques applied to the response of detectors in conformal antenna arrays. This approach utilizes photonic techniques that enable us to capture, route, and process the incoming signals. Optical modulators convert the incoming signals up to and exceeding 110 GHz with appreciable conversion efficiency and route these signals via fiber optics to a central processing location. This central processor consists of a closed loop phase control system which compensates for phase fluctuations induced on the fibers due to thermal or acoustic vibrations as well as an optical heterodyne approach for signal conversion down to baseband. Our optical heterodyne approach uses injection-locked paired optical sources to perform heterodyne downconversion/frequency identification of the detected emission. Preliminary geolocation and frequency identification testing of electronic emissions has been performed demonstrating the capabilities of our RF receiver.

  11. Iterative deconvolution technique for measurements of diffraction-limited images on optical microscopes.

    PubMed

    Lu, Wenlong; Chang, Ming; Chen, Po-Cheng; Luo, Wun-Mao

    2014-12-12

    Diffraction limit is usually a thorny problem in an optical inspection system. In this investigation, a model-based deconvolution technique was developed to recover diffraction-limited images, where images with sizes smaller than the diffraction limit could be recognized. Experiments were carried out with a traditional microscope at 200× magnification coupled with a halogen light source for a series of line width samples. The point spread function of the imaging optics was first obtained from an estimated model and then combined with a nonlinear deconvolution algorithm to calculate the full width at half maximum and reconstruct the line widths. Experimental results indicate that a measurement error below one pixel size of the measurement system is achievable. Accordingly, the target of nanoscale line width inspection based on a low cost and real-time image processing technique can be fulfilled, which greatly increases the ability of nanoscaling on optical microscopes.

  12. Reconstruction of elongated bubbles fusing the information from multiple optical probes through a Bayesian inference technique

    NASA Astrophysics Data System (ADS)

    Chakraborty, Shubhankar; Roy Chaudhuri, Partha; Das, Prasanta Kr.

    2016-07-01

    In this communication, a novel optical technique has been proposed for the reconstruction of the shape of a Taylor bubble using measurements from multiple arrays of optical sensors. The deviation of an optical beam passing through the bubble depends on the contour of bubble surface. A theoretical model of the deviation of a beam during the traverse of a Taylor bubble through it has been developed. Using this model and the time history of the deviation captured by the sensor array, the bubble shape has been reconstructed. The reconstruction has been performed using an inverse algorithm based on Bayesian inference technique and Markov chain Monte Carlo sampling algorithm. The reconstructed nose shape has been compared with the true shape, extracted through image processing of high speed images. Finally, an error analysis has been performed to pinpoint the sources of the errors.

  13. An optical fiber sensing technique for temperature distribution measurements in microwave heating

    NASA Astrophysics Data System (ADS)

    Wada, Daichi; Sugiyama, Jun-ichi; Zushi, Hiroaki; Murayama, Hideaki

    2015-08-01

    We introduce an optical fiber sensing technique that can measure the temperature distributions along a fiber during microwave heating. We used a long-length fiber Bragg grating (FBG) as an electromagnetic-immune sensor and interrogated temperature distributions along the FBG by an optical frequency domain reflectometry. Water in a glass tube with a length of 820 mm was heated in a microwave oven, and its temperature distribution along the glass tube was measured using the sensing system. The temperature distribution was obtained in 5 mm intervals. Infrared radiometry was also used to compare the temperature measurement results. Time and spatial variations of the temperature distribution profiles were monitored for several microwave input powers. The results clearly depict inhomogeneous temperature profiles. The applicability and effectiveness of the optical fiber distributed measurement technique in microwave heating are demonstrated.

  14. Molecular alignment enhancement phenomenon of polymer formed from a liquid crystal monomer in a liquid crystal solvent

    NASA Astrophysics Data System (ADS)

    Fujikake, Hideo; Murashige, Takeshi; Sato, Hiroto; Kawakita, Masahiro; Kikuchi, Hiroshi

    2003-03-01

    We report an abnormal alignment enhancement phenomenon of polymer molecules. The alignment order of a rigid-skeleton polymer made from a liquid crystalline monomer in a low-molecular-weight liquid crystal solvent was drastically enhanced with increasing temperature, even though the alignment order of the solution of the liquid crystal and monomer decreased. From polymer molecular alignment observations using polarizing Raman scattering microscopy, it was found that the polymer alignment order was three times greater than that of the original aligned monomer and polymer. This super alignment technique of polymer using a molecular-scaled self-assembly mechanism is applicable to the formation of electrically and/or optically functional nanopolymer wires.

  15. Novel failure analysis techniques using photon probing with a scanning optical microscope

    SciTech Connect

    Cole, E.I. Jr.; Soden, J.M.; Rife, J.L.; Barton, D.L.; Henderson, C.L.

    1993-12-31

    Three new failure analysis techniques for integrated circuits (ICs) have been developed using localized photon probing with a scanning optical microscope (SOM). The first two are light-induced voltage alteration (LIVA) imaging techniques that (1) localize open-circuited and damaged junctions and (2) image transistor logic states. The third technique uses the SOM to control logic states optically from the IC backside. LIVA images are produced by monitoring the voltage fluctuations of a constant current power supply as a laser beam is scanned over the IC. High selectivity for localizing defects has been demonstrated using the LIVA approach. Logic state mapping results, similar to previous work using biased optical beam induced current (OBIC) and laser probing approaches have also been produced using LIVA. Application of the two LIVA based techniques to backside failure analysis has been demonstrated using an infrared laser source. Optical logic state control is based upon earlier work examining transistor response to photon injection. The physics of each method and their applications for failure analysis are described.

  16. Novel VCSEL driving technique with virtual back termination for high-speed optical interconnection

    NASA Astrophysics Data System (ADS)

    Sugawara, Mariko; Tsunoda, Yukito; Oku, Hideki; Ide, Satoshi; Tanaka, Kazuhiro

    2012-01-01

    In this work, we develop a simple and high-speed VCSEL driving technique with "virtual back termination" for optical interconnect applications. For achieving compact and high-speed optical interconnects, an optical module with the flipchip bonding structure is effective. To realize flip-chip mounting, the development of the VCSEL driving technique, which can perform impedance matching with the transmission line, is a critical issue. Back termination has to be implemented to reduce signal reflection via the transmission line. Additionally, back termination must have a simple dc coupling. Introducing a virtual GND to the circuit ensures that these requirements are met. The virtual GND is made by a dummy load connected to a complementary output and dc-coupled 50-Ω resisters between output and complementary output. The dummy load has characteristics similar to the load VCSEL. As a result of the virtual GND, the resisters act as the back termination. When we drove the VCSEL with this technique, clear eye opening without the reflectance effects was obtained up to 28-Gb/s despite using a 10-cm transmission These results show that our driving technique is suitable for high-speed optical interconnect applications.

  17. Hardware Implementation of Multiple Fan Beam Projection Technique in Optical Fibre Process Tomography

    PubMed Central

    Rahim, Ruzairi Abdul; Fazalul Rahiman, Mohd Hafiz; Leong, Lai Chen; Chan, Kok San; Pang, Jon Fea

    2008-01-01

    The main objective of this project is to implement the multiple fan beam projection technique using optical fibre sensors with the aim to achieve a high data acquisition rate. Multiple fan beam projection technique here is defined as allowing more than one emitter to transmit light at the same time using the switch-mode fan beam method. For the thirty-two pairs of sensors used, the 2-projection technique and 4-projection technique are being investigated. Sixteen sets of projections will complete one frame of light emission for the 2-projection technique while eight sets of projection will complete one frame of light emission for the 4-projection technique. In order to facilitate data acquisition process, PIC microcontroller and the sample and hold circuit are being used. This paper summarizes the hardware configuration and design for this project. PMID:27879885

  18. Current achievements of nanoparticle applications in developing optical sensing and imaging techniques

    NASA Astrophysics Data System (ADS)

    Choi, Jong-ryul; Shin, Dong-Myeong; Song, Hyerin; Lee, Donghoon; Kim, Kyujung

    2016-11-01

    Metallic nanostructures have recently been demonstrated to improve the performance of optical sensing and imaging techniques due to their remarkable localization capability of electromagnetic fields. Particularly, the zero-dimensional nanostructure, commonly called a nanoparticle, is a promising component for optical measurement systems due to its attractive features, e.g., ease of fabrication, capability of surface modification and relatively high biocompatibility. This review summarizes the work to date on metallic nanoparticles for optical sensing and imaging applications, starting with the theoretical backgrounds of plasmonic effects in nanoparticles and moving through the applications in Raman spectroscopy and fluorescence biosensors. Various efforts for enhancing the sensitivity, selectivity and biocompatibility are summarized, and the future outlooks for this field are discussed. Convergent studies in optical sensing and imaging have been emerging field for the development of medical applications, including clinical diagnosis and therapeutic applications.

  19. Simple, generalizable route to highly aligned block copolymer thin films

    NASA Astrophysics Data System (ADS)

    Qiang, Zhe; Cavicchi, Kevin; Vogt, Bryan

    2015-03-01

    Macroscopic alignment of block copolymer domains in thin films is desired for many applications, such as cell responsive surfaces or optical polarizers. Alignment generally requires specialized tools that apply external fields, shear force gradient, or produce topological patterned substrates. This requirement limits the broad academic application of aligned BCPs. Here, we describe a simple modification of commonly utilized solvent vapor annealing (SVA) process for macroscopic alignment of BCPs. Adhering a flat, crosslinked elastomer pad to the BCP film leads to differential swelling between the elastomer pad and BCP to produce a shear force that aligns the ordered BCP domains. The role of elastomer properties, solvent quality, drying rate and degree of segregation of the block copolymer will be discussed to provide generalized rules for alignment with this technique. Cylindrical nanostructures formed in polystyrene-block-polydimethylsiloxane can be transformed into arrays of silica lines and increasing the thickness from a monolayer to bilayer can effectively halve the spacing of the lines. These results illustrate a generalized method for BCP alignment and a potential route for the generation of complex hierarchical assembled structures.

  20. 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.

  1. Precoding techniques for PAPR reduction in asymmetrically clipped OFDM based optical wireless system

    NASA Astrophysics Data System (ADS)

    Ranjha, Bilal; Kavehrad, Mohsen

    2013-01-01

    In this paper, we have analyzed different precoding based Peak-to-Average-Power (PAPR) reduction techniques for asymmetrically-clipped Orthogonal Frequency Division Multiplexing (OFDM) optical wireless communication systems. Intensity Modulated Direct Detection (IM/DD) technique is among the popular techniques for optical wireless communication systems. OFDM cannot be directly applied to IM systems because of the bipolar nature of the output signal. Therefore some variants of OFDM systems have been proposed for (IM/DD) optical wireless systems. Among them are DC-biased-OFDM, Asymmetrically-Clipped Optical OFDM (ACO-OFDM) [2] and Pulse Amplitude Modulated Discrete Multitone (PAM-DMT) [3]. Both ACO-OFDM and PAM-DMT require low average power and thus are very attractive for optical wireless systems. OFDM systems suffer from high PAPR problem that can limit its performance due to non-linear characteristics of LED. Therefore PAPR reduction techniques have to be employed. This paper analyzes precoding based PAPR reduction methods for ACO-OFDM and PAM-DMT. We have used Discrete Fourier Transform (DFT) coding, Zadoff-Chu Transform (ZCT) [8] and Discrete Cosine Transform (DCT) for ACOOFDM and only DCT for PAM-DMT since the modulating symbols are real. We have compared the performance of these precoding techniques using different QAM modulation schemes. Simulation results have shown that both DFT and ZCT offer more PAPR reduction than DCT in ACO-OFDM. For PAM-DMT, DCT precoding yields significant PAPR reduction compared to conventional PAM-DMT signal. These precoding schemes also offer the advantage of zero signaling overhead.

  2. RECAT - Redundant Channel Alignment Technique

    DTIC Science & Technology

    2016-06-07

    NAVAL UNDERWATER SYSTEMS CENTER NEW LONDON LABORATORY NEW LONDON, CONNECTICUT 06320 Techn1cal Memorandum TM No . 861118 RECAT - REDUNDANT...PROJECT NUMBER B69025 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Naval Underwater Systems Center, New ...London Laboratory, New London,CT,06320 8. PERFORMING ORGANIZATION REPORT NUMBER TM No. 861118 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10

  3. VIRUS spectrograph assembly and alignment procedures

    NASA Astrophysics Data System (ADS)

    Prochaska, Travis; Allen, Richard D.; Boster, Emily; DePoy, D. L.; Herbig, Benjamin; Hill, Gary J.; Lee, Hanshin; Marshall, Jennifer L.; Martin, Emily C.; Meador, William; Rheault, Jean-Philippe; Tuttle, Sarah E.; Vattiat, Brian L.

    2012-09-01

    We describe the mechanical assembly and optical alignment processes used to construct the Visual Integral-Field Replicable Unit Spectrograph (VIRUS) instrument. VIRUS is a set of 150+ optical spectrographs designed to support observations for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). To meet the instrument's manufacturing constraints, a production line will be set up to build subassemblies in parallel. To aid in the instrument's assembly and alignment, specialized fixtures and adjustment apparatuses have been developed. We describe the design and operations of the various optics alignment apparatuses, as well as the mirrors' alignment and bonding fixtures.

  4. Neutron, fluorescence, and optical imaging: An in situ combination of complementary techniques

    SciTech Connect

    Wagner, D.; Egelhaaf, S. U.; Hermes, H. E.; Börgardts, M.; Müller, T. J. J.; Grünzweig, C.; Lehmann, E.

    2015-09-15

    An apparatus which enables the simultaneous combination of three complementary imaging techniques, optical imaging, fluorescence imaging, and neutron radiography, is presented. While each individual technique can provide information on certain aspects of the sample and their time evolution, a combination of the three techniques in one setup provides a more complete and consistent data set. The setup can be used in transmission and reflection modes and thus with optically transparent as well as opaque samples. Its capabilities are illustrated with two examples. A polymer hydrogel represents a transparent sample and the diffusion of fluorescent particles into and through this polymer matrix is followed. In reflection mode, the absorption of solvent by a nile red-functionalized mesoporous silica powder and the corresponding change in fluorescent signal are studied.

  5. Molecular imaging with optics: primer and case for near-infrared fluorescence techniques in personalized medicine.

    PubMed

    Sevick-Muraca, Eva M; Rasmussen, John C

    2008-01-01

    We compare and contrast the development of optical molecular imaging techniques with nuclear medicine with a didactic emphasis for initiating readers into the field of molecular imaging. The nuclear imaging techniques of gamma scintigraphy, single-photon emission computed tomography, and positron emission tomography are first briefly reviewed. The molecular optical imaging techniques of bioluminescence and fluorescence using gene reporter/probes and gene reporters are described prior to introducing the governing factors of autofluorescence and excitation light leakage. The use of dual-labeled, near-infrared excitable and radio-labeled agents are described with comparative measurements between planar fluorescence and nuclear molecular imaging. The concept of time-independent and -dependent measurements is described with emphasis on integrating time-dependent measurements made in the frequency domain for 3-D tomography. Finally, we comment on the challenges and progress for translating near-infrared (NIR) molecular imaging agents for personalized medicine.

  6. Techniques for generation of control and guidance signals derived from optical fields, part 2

    NASA Technical Reports Server (NTRS)

    Hemami, H.; Mcghee, R. B.; Gardner, S. R.

    1971-01-01

    The development is reported of a high resolution technique for the detection and identification of landmarks from spacecraft optical fields. By making use of nonlinear regression analysis, a method is presented whereby a sequence of synthetic images produced by a digital computer can be automatically adjusted to provide a least squares approximation to a real image. The convergence of the method is demonstrated by means of a computer simulation for both elliptical and rectangular patterns. Statistical simulation studies with elliptical and rectangular patterns show that the computational techniques developed are able to at least match human pattern recognition capabilities, even in the presence of large amounts of noise. Unlike most pattern recognition techniques, this ability is unaffected by arbitrary pattern rotation, translation, and scale change. Further development of the basic approach may eventually allow a spacecraft or robot vehicle to be provided with an ability to very accurately determine its spatial relationship to arbitrary known objects within its optical field of view.

  7. Finite-difference time-domain-based optical microscopy simulation of dispersive media facilitates the development of optical imaging techniques

    NASA Astrophysics Data System (ADS)

    Zhang, Di; Capoglu, Ilker; Li, Yue; Cherkezyan, Lusik; Chandler, John; Spicer, Graham; Subramanian, Hariharan; Taflove, Allen; Backman, Vadim

    2016-06-01

    Combining finite-difference time-domain (FDTD) methods and modeling of optical microscopy modalities, we previously developed an open-source software package called Angora, which is essentially a "microscope in a computer." However, the samples being simulated were limited to nondispersive media. Since media dispersions are common in biological samples (such as cells with staining and metallic biomarkers), we have further developed a module in Angora to simulate samples having complicated dispersion properties, thereby allowing the synthesis of microscope images of most biological samples. We first describe a method to integrate media dispersion into FDTD, and we validate the corresponding Angora dispersion module by applying Mie theory, as well as by experimentally imaging gold microspheres. Then, we demonstrate how Angora can facilitate the development of optical imaging techniques with a case study.

  8. Optical brain imaging in vivo: techniques and applications from animal to man

    PubMed Central

    Hillman, Elizabeth M. C.

    2008-01-01

    Optical brain imaging has seen 30 years of intense development, and has grown into a rich and diverse field. In-vivo imaging using light provides unprecedented sensitivity to functional changes through intrinsic contrast, and is rapidly exploiting the growing availability of exogenous optical contrast agents. Light can be used to image microscopic structure and function in vivo in exposed animal brain, while also allowing noninvasive imaging of hemodynamics and metabolism in a clinical setting. This work presents an overview of the wide range of approaches currently being applied to in-vivo optical brain imaging, from animal to man. Techniques include multispectral optical imaging, voltage sensitive dye imaging and speckle-flow imaging of exposed cortex, in-vivo two-photon microscopy of the living brain, and the broad range of noninvasive topography and tomography approaches to near-infrared imaging of the human brain. The basic principles of each technique are described, followed by examples of current applications to cutting-edge neuroscience research. In summary, it is shown that optical brain imaging continues to grow and evolve, embracing new technologies and advancing to address ever more complex and important neuroscience questions. PMID:17994863

  9. Optical brain imaging in vivo: techniques and applications from animal to man.

    PubMed

    Hillman, Elizabeth M C

    2007-01-01

    Optical brain imaging has seen 30 years of intense development, and has grown into a rich and diverse field. In-vivo imaging using light provides unprecedented sensitivity to functional changes through intrinsic contrast, and is rapidly exploiting the growing availability of exogenous optical contrast agents. Light can be used to image microscopic structure and function in vivo in exposed animal brain, while also allowing noninvasive imaging of hemodynamics and metabolism in a clinical setting. This work presents an overview of the wide range of approaches currently being applied to in-vivo optical brain imaging, from animal to man. Techniques include multispectral optical imaging, voltage sensitive dye imaging and speckle-flow imaging of exposed cortex, in-vivo two-photon microscopy of the living brain, and the broad range of noninvasive topography and tomography approaches to near-infrared imaging of the human brain. The basic principles of each technique are described, followed by examples of current applications to cutting-edge neuroscience research. In summary, it is shown that optical brain imaging continues to grow and evolve, embracing new technologies and advancing to address ever more complex and important neuroscience questions.

  10. Parallel aligned liquid crystal on silicon display based optical set-up for the generation of polarization spatial distributions

    NASA Astrophysics Data System (ADS)

    Estévez, Irene; Lizana, Angel; Zheng, Xuejie; Peinado, Alba; Ramírez, Claudio; Martínez, Jose Luis; Márquez, Andrés.; Moreno, Ignacio; Campos, Juan

    2015-06-01

    Liquid Crystals on Silicon (LCOS) displays are a type of LCDs that work in reflection. Such devices, due to the double pass that the light beam performs through the LC cells, lead to larger phase modulation than transmissive LCDs with the same thickness. By taking advantage of this modulation capability exhibited by LCOS displays, we propose a new experimental set-up which is able to provide customized state of polarization spatial distributions just by means of a single LCOS display. To this aim, a double reflection on different halves of the display is properly performed. This fact is achieved by including a compact optical system that steers the light and performs a proper polarization plane rotation. The set-up has been experimentally implemented and some experimental concerns are discussed. The suitability of the system is provided by generating different experimental spatial distributions of polarization. In this regard, well-known polarization distributions, as axial, azimuthal or spiral linear polarization patterns are here provided. Based on the excellent results obtained, the suitability of the system to generate different spatially variant distributions of polarization is validated.

  11. New optical gating technique for detection of electric field waveforms with subpicosecond resolution.

    PubMed

    Muraviev, Andrey; Gutin, Alexey; Rupper, Greg; Rudin, Sergey; Shen, Xiaohan; Yamaguchi, Masashi; Aizin, Gregory; Shur, Michael

    2016-06-13

    The new optical gating technique uses a femtosecond optical laser pulses for the photoconductive detection of short pulses of terahertz (THz) radiation. This technique reproduces the shape of the THz pulse and after pulse plasmonic response of the two-dimensional electron gas in a short channel high electron mobility transistor (HEMT). The results are in excellent agreement with the electro-optic effect measurements and with the simulation results obtained in the frame of a two-dimensional hydrodynamic model. The femtosecond optical laser pulse time is delayed with respect to the THz pulse and generates a large concentration of the electron-hole pairs in the AlGaAs/InGaAs HEMT. This drastically increases the channel conductivity on the femtosecond scale and effectively shorts the device quenching the transistor response. The achieved time resolution is better than 250 femtoseconds and could be improved using shorter femtosecond laser pulses. The spatial resolution of this technique is on the order of tens of nanometers or even smaller. It could be applied for studying the electron transport in a variety of electronic devices ranging from silicon MOSFETs to heterostructure bipolar transistors.

  12. A fiber-optic diagnostic technique for mechanical detection of the laser-metal interaction underwater

    NASA Astrophysics Data System (ADS)

    Xu, R. Q.; Chen, X.; Shen, Z. H.; Lu, J.; Ni, X. W.

    2004-03-01

    A new fiber-optic force sensor based on optical beam deflection for the investigation of the mechanical effects during laser-metal interaction underwater is developed. This sensor is applied to detect the laser-induced plasma ablation force and liquid-jet impact during the cavitation bubble collapse near a solid boundary when a Q-switched laser is focused on a metal in water. The experimental results indicate the liquid-jet effect outweighs the well-known laser-induced plasma ablation force. This technique has the advantages of high-frequency response, simple structure, and nondestructive examination.

  13. Optical Deflection Technique for Investigation of Laser-Induced Oscillating Bubble on Metal Surface

    NASA Astrophysics Data System (ADS)

    Xu, Rong-Qing; Chen, Xiao; Shen, Zhong-Hua; Lu, Jian; Ni, Xiao-Wu

    2004-08-01

    The oscillation of a laser-generated single cavitation bubble on a metal surface is investigated by a fiber-optic diagnostic technique based on an optical beam deflection (OBD). The sequence of waveforms induced by the bubble pulsation is obtained with respect to detection distance. The maximum and minimum bubble radii for each oscillation cycle are determined from the experimental results. Furthermore, by tracking the arrival time of a bubble wall during its expanding and collapsing stages, the temporal development of a cavitation bubble on the metal surface is obtained.

  14. Thirteen new BL Lacertae objects discovered by an efficient x ray/radio/optical technique

    NASA Technical Reports Server (NTRS)

    Schachter, Jonathan F.; Stocke, John T.; Perlman, Eric; Elvis, Martin S.; Luu, Jane; Huchra, John P.; Humphreys, Roberta; Remillard, Ron; Wallin, John

    1992-01-01

    The discovery of 13 serendipitous BL Lac objects in the Einstein IPC Slew Survey by means of x ray/radio vs. x ray/optical color-color diagrams and confirmation by optical spectroscopy are reported. These 13 BL Lacs were discovered using a technique which exploits the characteristic broad band spectra of BL Lacs. New VLA detections provide accurate fluxes (f(6 cm) is approximately 0.5 mJy) and 2 in. positions, facilitating the determination of an optical counterpart. All 13 new BL Lacs show essentially featureless optical spectra. Nine of these lie within the range of colors of known x ray selected BL Lacs. Of the remaining four, one is apparently x ray louder (by a factor of 1.5) or optically quieter (by 0.8 mags); and three are optically louder (by 1-1.3 mags) than x ray selected BL Lacs. Approximately 50 new BL Lacs in total are expected from VLA work and upcoming Australia Telescope observations, yielding a complete Slew Survey sample of approximately 90 BL Lacs.

  15. Prism coupling technique investigation of elasto-optical properties of thin polymer films

    NASA Astrophysics Data System (ADS)

    Ay, Feridun; Kocabas, Askin; Kocabas, Coskun; Aydinli, Atilla; Agan, Sedat

    2004-12-01

    The use of thin polymer films in optical planar integrated optical circuits is rapidly increasing. Much interest, therefore, has been devoted to characterizing the optical and mechanical properties of thin polymer films. This study focuses on measuring the elasto-optical properties of three different polymers; polystyrene, polymethyl-methacrylate, and benzocyclobutane. The out-of-plane elastic modulus, refractive index, film thickness, and birefringence of thin polymer films were determined by means of the prism coupling technique. The effect of the applied stress on the refractive index and birefringence of the films was investigated. Three-dimensional finite element method analysis was used so as to obtain the principal stresses for each polymer system, and combining them with the stress dependent refractive index measurements, the elasto-optic coefficients of the polymer films were determined. It was found that the applied stress in the out-of-plane direction of the thin films investigated leads to negative elasto-optic coefficients, as observed for all the three thin polymer films.

  16. ALIGNING JIG

    DOEpatents

    Culver, J.S.; Tunnell, W.C.

    1958-08-01

    A jig or device is described for setting or aligning an opening in one member relative to another member or structure, with a predetermined offset, or it may be used for measuring the amount of offset with which the parts have previously been sct. This jig comprises two blocks rabbeted to each other, with means for securing thc upper block to the lower block. The upper block has fingers for contacting one of the members to be a1igmed, the lower block is designed to ride in grooves within the reference member, and calibration marks are provided to determine the amount of offset. This jig is specially designed to align the collimating slits of a mass spectrometer.

  17. Radio frequency phototube and optical clock: High resolution, high rate and highly stable single photon timing technique

    SciTech Connect

    Margaryan, Amur

    2011-10-01

    A new timing technique for single photons based on the radio frequency phototube and optical clock or femtosecond optical frequency comb generator is proposed. The technique has a 20 ps resolution for single photons, is capable of operating with MHz frequencies and achieving 10 fs instability level.

  18. The Optical Flow Technique on the Research of Solar Non-potentiality

    NASA Astrophysics Data System (ADS)

    Liu, Ji-hong; Zhang, Hong-qi

    2010-06-01

    Several optical flow techniques, which have being applied to the researches of solar magnetic non-potentiality recently, have been summarized here. And a few new non-potential parameters which can be derived from them have been discussed, too. The main components of the work are presented as follows: (1) The optical flow techniques refers to a series of new image analyzing techniques arisen recently on the researches of solar magnetic non-potentiality. They mainly include LCT (local correlation tracking), ILCT (inductive equation combining with LCT), MEF (minimum energy effect), DAVE (differential affine velocity estimator) and NAVE (nonlinear affine velocity estimator). Their calculating and applying conditions, merits and deficiencies, all have been discussed detailedly in this work. (2) Benefit from the optical flow techniques, the transverse velocity fields of the magnetic features on the solar surface may be determined by a time sequence of high-quality images currently produced by high-resolution observations either from the ground or in space. Consequently, several new non-potential parameters may be acquired, such as the magnetic helicity flux, the induced electric field in the photosphere, the non-potential magnetic stress (whose area integration is the Lorentz force), etc. Then we can determine the energy flux across the photosphere, and subsequently evaluate the energy budget. Former works on them by small or special samples have shown that they are probably related closely to the erupting events, such as flare, filament eruptions and coronal mass ejections.

  19. Using Complementary Acoustic and Optical Techniques for Quantitative Monitoring of Biomolecular Adsorption at Interfaces

    PubMed Central

    Konradi, Rupert; Textor, Marcus; Reimhult, Erik

    2012-01-01

    The great wealth of different surface sensitive techniques used in biosensing, most of which claim to measure adsorbed mass, can at first glance look unnecessary. However, with each technique relying on a different transducer principle there is something to be gained from a comparison. In this tutorial review, different optical and acoustic evanescent techniques are used to illustrate how an understanding of the transducer principle of each technique can be exploited for further interpretation of hydrated and extended polymer and biological films. Some of the most commonly used surface sensitive biosensor techniques (quartz crystal microbalance, optical waveguide spectroscopy and surface plasmon resonance) are briefly described and five case studies are presented to illustrate how different biosensing techniques can and often should be combined. The case studies deal with representative examples of adsorption of protein films, polymer brushes and lipid membranes, and describe e.g., how to deal with strongly vs. weakly hydrated films, large conformational changes and ordered layers of biomolecules. The presented systems and methods are compared to other representative examples from the increasing literature on the subject. PMID:25586027

  20. Image alignment

    DOEpatents

    Dowell, Larry Jonathan

    2014-04-22

    Disclosed is a method and device for aligning at least two digital images. An embodiment may use frequency-domain transforms of small tiles created from each image to identify substantially similar, "distinguishing" features within each of the images, and then align the images together based on the location of the distinguishing features. To accomplish this, an embodiment may create equal sized tile sub-images for each image. A "key" for each tile may be created by performing a frequency-domain transform calculation on each tile. A information-distance difference between each possible pair of tiles on each image may be calculated to identify distinguishing features. From analysis of the information-distance differences of the pairs of tiles, a subset of tiles with high discrimination metrics in relation to other tiles may be located for each image. The subset of distinguishing tiles for each image may then be compared to locate tiles with substantially similar keys and/or information-distance metrics to other tiles of other images. Once similar tiles are located for each image, the images may be aligned in relation to the identified similar tiles.

  1. The Optics and Alignment of the Divergent Beam Laboratory X-ray Powder Diffractometer and its Calibration Using NIST Standard Reference Materials

    PubMed Central

    Cline, James P.; Mendenhall, Marcus H.; Black, David; Windover, Donald; Henins, Albert

    2015-01-01

    The laboratory X-ray powder diffractometer is one of the primary analytical tools in materials science. It is applicable to nearly any crystalline material, and with advanced data analysis methods, it can provide a wealth of information concerning sample character. Data from these machines, however, are beset by a complex aberration function that can be addressed through calibration with the use of NIST Standard Reference Materials (SRMs). Laboratory diffractometers can be set up in a range of optical geometries; considered herein are those of Bragg-Brentano divergent beam configuration using both incident and diffracted beam monochromators. We review the origin of the various aberrations affecting instruments of this geometry and the methods developed at NIST to align these machines in a first principles context. Data analysis methods are considered as being in two distinct categories: those that use empirical methods to parameterize the nature of the data for subsequent analysis, and those that use model functions to link the observation directly to a specific aspect of the experiment. We consider a multifaceted approach to instrument calibration using both the empirical and model based data analysis methods. The particular benefits of the fundamental parameters approach are reviewed. PMID:26958446

  2. The Optics and Alignment of the Divergent Beam Laboratory X-ray Powder Diffractometer and its Calibration Using NIST Standard Reference Materials.

    PubMed

    Cline, James P; Mendenhall, Marcus H; Black, David; Windover, Donald; Henins, Albert

    2015-01-01

    The laboratory X-ray powder diffractometer is one of the primary analytical tools in materials science. It is applicable to nearly any crystalline material, and with advanced data analysis methods, it can provide a wealth of information concerning sample character. Data from these machines, however, are beset by a complex aberration function that can be addressed through calibration with the use of NIST Standard Reference Materials (SRMs). Laboratory diffractometers can be set up in a range of optical geometries; considered herein are those of Bragg-Brentano divergent beam configuration using both incident and diffracted beam monochromators. We review the origin of the various aberrations affecting instruments of this geometry and the methods developed at NIST to align these machines in a first principles context. Data analysis methods are considered as being in two distinct categories: those that use empirical methods to parameterize the nature of the data for subsequent analysis, and those that use model functions to link the observation directly to a specific aspect of the experiment. We consider a multifaceted approach to instrument calibration using both the empirical and model based data analysis methods. The particular benefits of the fundamental parameters approach are reviewed.

  3. Alignment of the MINOS FD

    SciTech Connect

    Becker, B.; Boehnlein, D.; /Fermilab

    2004-11-01

    The results and procedure of the alignment of the MINOS Far Detector are presented. The far detector has independent alignments of SM1 and SM2. The misalignments have an estimated uncertainty of {approx}850 {micro}m for SM1 and {approx}750 {micro}m for SM2. The alignment has as inputs the average rotations of U and V as determined by optical survey and strip positions within modules measured from the module mapper. The output of this is a module-module correction for transverse mis-alignments. These results were verified by examining an independent set of data. These alignment constants on average contribute much less then 1% to the total uncertainty in the transverse strip position.

  4. Dynamic interferometer alignment and its utility in UV Fourier transform spectrometer systems

    NASA Technical Reports Server (NTRS)

    Dorval, Rick K.; Engel, James R.; Wyntjes, Geert J.

    1993-01-01

    Dynamic alignment has been demonstrated as a practical approach to alignment maintenance for systems in the infrared region of the spectrum. On the basis of work done by OPTRA, this technique was introduced in commercial Fourier transform spectrometer systems in 1982 and in various forms is now available from a number of manufacturers. This paper reports on work by OPTRA to extend the basic technique to systems operating in the ultraviolet. In addition, this paper reports the preliminary results of the development of an alignment system using a laser diode in place of a gas laser normally found in dynamic alignment systems. A unique optical system and spatial heterodyne technique allows for achievement of a metrology system with characteristics that fully satisfy the requirements of an ultraviolet spectrometer system.

  5. Methodology for optimal in situ alignment and setting of bendable optics for nearly diffraction-limited focusing of soft x-rays

    NASA Astrophysics Data System (ADS)

    Merthe, Daniel J.; Yashchuk, Valeriy V.; Goldberg, Kenneth A.; Kunz, Martin; Tamura, Nobumichi; McKinney, Wayne R.; Artemiev, Nikolay A.; Celestre, Richard S.; Morrison, Gregory Y.; Anderson, Erik H.; Smith, Brian V.; Domning, Edward E.; Rekawa, Senajith B.; Padmore, Howard A.

    2013-03-01

    We demonstrate a comprehensive and broadly applicable methodology for the optimal in situ configuration of bendable soft x-ray Kirkpatrick-Baez mirrors. The mirrors used for this application are preset at the Advanced Light Source Optical Metrology Laboratory prior to beamline installation. The in situ methodology consists of a new technique for simultaneously setting the height and pitch angle of each mirror. The benders of both mirrors were then optimally tuned in order to minimize ray aberrations to a level below the diffraction-limited beam waist size of 200 nm (horizontal)×100 nm (vertical). After applying this methodology, we measured a beam waist size of 290 nm (horizontal)×130 nm (vertical) with 1 nm light using the Foucault knife-edge test. We also discuss the utility of using a grating-based lateral shearing interferometer with quantitative wavefront feedback for further improvement of bendable optics.

  6. Methodology for optimal in situ alignment and setting of bendable optics for diffraction-limited focusing of soft x-rays

    NASA Astrophysics Data System (ADS)

    Merthe, Daniel J.; Yashchuk, Valeriy V.; Goldberg, Kenneth A.; Kunz, Martin; Tamura, Nobumichi; McKinney, Wayne R.; Artemiev, Nikolay A.; Celestre, Richard S.; Morrison, Gregory Y.; Anderson, Erik; Smith, Brian V.; Domning, Edward E.; Rekawa, Senajith B.; Padmore, Howard A.

    2012-09-01

    We demonstrate a comprehensive and broadly applicable methodology for the optimal in situ configuration of bendable soft x-ray Kirkpatrick-Baez mirrors. The mirrors used for this application are preset at the ALS Optical Metrology Laboratory prior to beamline installation. The in situ methodology consists of a new technique for simultaneously setting the height and pitch angle of each mirror. The benders of both mirrors were then optimally tuned in order to minimize ray aberrations to a level below the diffraction-limited beam waist size of 200 nm (horizontal) × 100 nm (vertical). After applying this methodology, we measured a beam waist size of 290 nm (horizontal) × 130 nm (vertical) with 1 nm light using the Foucault knife-edge test. We also discuss the utility of using a grating-based lateral shearing interferometer with quantitative wavefront feedback for further improvement of bendable optics.

  7. Optical burst add-drop multiplexing technique for sub-wavelength granularity in wavelength multiplexed ring networks.

    PubMed

    Cho, Jeong Sik; Seo, Young Kwang; Yoo, Hark; Park, Paul K; Rhee, June-Koo; Won, Yong Hyub; Kang, Min Ho

    2007-10-01

    We demonstrate optical burst add-drop multiplexing as a practical application of the optical burst switching technology in a wavelength-division-multiplexed ring network. To control optical bursts in the network, a burst identifier (BI) for delivering control information, and a BI processor for handling the BI, were designed. Optical bursts of 10- to 100-mus in length were optically multiplexed or demultiplexed in an intermediate node of the ring network. The demonstration shows that the optical burst add-drop multiplexing technique provides sub-wavelength granularity to a ring network.

  8. MUSE alignment onto VLT

    NASA Astrophysics Data System (ADS)

    Laurent, Florence; Renault, Edgard; Boudon, Didier; Caillier, Patrick; Daguisé, Eric; Dupuy, Christophe; Jarno, Aurélien; Lizon, Jean-Louis; Migniau, Jean-Emmanuel; Nicklas, Harald; Piqueras, Laure

    2014-07-01

    MUSE (Multi Unit Spectroscopic Explorer) is a second generation Very Large Telescope (VLT) integral field spectrograph developed for the European Southern Observatory (ESO). It combines a 1' x 1' field of view sampled at 0.2 arcsec for its Wide Field Mode (WFM) and a 7.5"x7.5" field of view for its Narrow Field Mode (NFM). Both modes will operate with the improved spatial resolution provided by GALACSI (Ground Atmospheric Layer Adaptive Optics for Spectroscopic Imaging), that will use the VLT deformable secondary mirror and 4 Laser Guide Stars (LGS) foreseen in 2015. MUSE operates in the visible wavelength range (0.465-0.93 μm). A consortium of seven institutes is currently commissioning MUSE in the Very Large Telescope for the Preliminary Acceptance in Chile, scheduled for September, 2014. MUSE is composed of several subsystems which are under the responsibility of each institute. The Fore Optics derotates and anamorphoses the image at the focal plane. A Splitting and Relay Optics feed the 24 identical Integral Field Units (IFU), that are mounted within a large monolithic structure. Each IFU incorporates an image slicer, a fully refractive spectrograph with VPH-grating and a detector system connected to a global vacuum and cryogenic system. During 2012 and 2013, all MUSE subsystems were integrated, aligned and tested to the P.I. institute at Lyon. After successful PAE in September 2013, MUSE instrument was shipped to the Very Large Telescope in Chile where that was aligned and tested in ESO integration hall at Paranal. After, MUSE was directly transported, fully aligned and without any optomechanical dismounting, onto VLT telescope where the first light was overcame the 7th of February, 2014. This paper describes the alignment procedure of the whole MUSE instrument with respect to the Very Large Telescope (VLT). It describes how 6 tons could be move with accuracy better than 0.025mm and less than 0.25 arcmin in order to reach alignment requirements. The success

  9. Image reconstruction using wavelet multi-resolution technique for time-domain diffuse optical tomography

    NASA Astrophysics Data System (ADS)

    Yang, Fang; Gao, Feng; Jiao, Yuting; Zhao, Huijuan

    2010-02-01

    It is generally believed that the inverse problem in diffuse optical tomography (DOT) is highly ill-posed and its solution is always under-determined and sensitive to noise, which is the main problem in the application of DOT. In this paper, we propose a method on image reconstruction for time-domain diffuse optical tomography based on panel detection and Finite-Difference Method, and introduce an approach to reduce the number of unknown parameters in the reconstruction process. We propose a multi-level scheme to reduce the number of unknowns by parameterizing the spatial distribution of optical properties via wavelet transform and then reconstruct the coefficients of this transform. Compared with previous traditional uni-level full spatial domain algorithm, this method can efficiently improve the reconstruction quality. Numerical simulations show that wavelet-based multi-level inversion is superior to the uni-level algebraic reconstruction technique.

  10. Fusion bonding and alignment fixture

    DOEpatents

    Ackler, Harold D.; Swierkowski, Stefan P.; Tarte, Lisa A.; Hicks, Randall K.

    2000-01-01

    An improved vacuum fusion bonding structure and process for aligned bonding of large area glass plates, patterned with microchannels and access holes and slots, for elevated glass fusion temperatures. Vacuum pumpout of all the components is through the bottom platform which yields an untouched, defect free top surface which greatly improves optical access through this smooth surface. Also, a completely non-adherent interlayer, such as graphite, with alignment and location features is located between the main steel platform and the glass plate pair, which makes large improvements in quality, yield, and ease of use, and enables aligned bonding of very large glass structures.

  11. Development of surface thermal lensing technique in absorption and defect analyses of optical coatings

    NASA Astrophysics Data System (ADS)

    He, Hongbo; Li, Xia; Fan, Shuhai; Shao, Jianda; Zhao, Yuanan; Fan, Zhengxiu

    2005-12-01

    Absorption is one of the main factors which cause damage to optical coatings, under the radiation of high power lasers. Surface thermal lensing (STL) technique was developed into a practical high-sensitivity apparatus for the weak absorption analysis of optical coatings. A 20 W continuous-wave 1064 nm Nd:YAG laser and a 30 mW He-Ne laser were employed as pump source and probe source, respectively. Low noise photoelectrical components and an SR830 DSP lock-in amplifier were used for photo-thermal deformation signal detection. In order to improve sensitivity, the configuration of the apparatus was optimized through choosing appropriate parameters, that including pump beam spot size, chopper frequency, detection distance, waist radius and position of probe beam. Coating samples were mounted on an x-y stage which was driven by high precision stepper motors. Different processes of absorption measurements, including single spot, linear scan and 2-dimension area scan, could be performed manually or automatically under the control of PC program. Various optical coatings were prepared by both electron beam evaporation and ion beam sputtering deposition. High sensitivity was obtained and low to 10 ppb absorption could be measured by surface thermal lensing technique. And a spatial resolution of 25 micron was proved according to the area scanning which traced out the profile of photo-thermal defects inside optical coatings. The system was employed in the analyses of optical absorption, absorption uniformity and defect distribution, and revealed the relationship between laser-induced damage and absorption of optical coatings.

  12. An approximate numerical technique for characterizing optical pulse propagation in inhomogeneous biological tissue.

    PubMed

    Handapangoda, Chintha C; Premaratne, Malin

    2008-01-01

    An approximate numerical technique for modeling optical pulse propagation through weakly scattering biological tissue is developed by solving the photon transport equation in biological tissue that includes varying refractive index and varying scattering/absorption coefficients. The proposed technique involves first tracing the ray paths defined by the refractive index profile of the medium by solving the eikonal equation using a Runge-Kutta integration algorithm. The photon transport equation is solved only along these ray paths, minimizing the overall computational burden of the resulting algorithm. The main advantage of the current algorithm is that it enables to discretise the pulse propagation space adaptively by taking optical depth into account. Therefore, computational efficiency can be increased without compromising the accuracy of the algorithm.

  13. A novel technique for estimating aerosol optical thickness trends using meteorological parameters

    NASA Astrophysics Data System (ADS)

    Emetere, Moses E.; Akinyemi, M. L.; Akin-Ojo, O.

    2016-02-01

    Estimating aerosol optical thickness (AOT) over regions can be tasking if satellite data set over such region is very scanty. Therefore a technique whose application captures real-time events is most appropriate for adequate monitoring of risk indicators. A new technique i.e. arithmetic translation of pictorial model (ATOPM) was developed. The ATOPM deals with the use mathematical expression to compute other meteorological parameters obtained from satellite or ground data set. Six locations within 335 × 230 Km2 area of a selected portion of Nigeria were chosen and analyzed -using the meteorological data set (1999-2012) and MATLAB. The research affirms the use of some parameters (e.g. minimum temperature, cloud cover, relative humidity and rainfall) to estimate the aerosol optical thickness. The objective of the paper was satisfied via the use of other meteorological parameters to estimate AOT when the satellite data set over an area is scanty.

  14. Vibration measurement based on the optical cross-correlation technique with femtosecond pulsed laser

    NASA Astrophysics Data System (ADS)

    Han, Jibo; Wu, Tengfei; Zhao, Chunbo; Li, Shuyi

    2016-10-01

    Two vibration measurement methods with femtosecond pulsed laser based on the optical cross-correlation technique are presented independently in this paper. The balanced optical cross-correlation technique can reflect the time jitter between the reference pluses and measurement pluses by detecting second harmonic signals using type II phase-matched nonlinear crystal and balanced amplified photo-detectors. In the first method, with the purpose of attaining the vibration displacement, the time difference of the reference pulses relative to the measurement pluses can be measured using single femtosecond pulsed laser. In the second method, there are a couple of femtosecond pulsed lasers with high pulse repetition frequency. Vibration displacement associated with cavity length can be calculated by means of precisely measuring the pulse repetition frequency. The results show that the range of measurement attains ±150μm for a 500fs pulse. These methods will be suited for vibration displacement measurement, including laboratory use, field testing and industrial application.

  15. An optical authentication system based on encryption technique and multimodal biometrics

    NASA Astrophysics Data System (ADS)

    Yuan, Sheng; Zhang, Tong; Zhou, Xin; Liu, Xuemei; Liu, Mingtang

    2013-12-01

    A major concern nowadays for a biometric credential management system is its potential vulnerability to protect its information sources. To prevent a genuine user's templates from both internal and external threats, a novel and simple method combined optical encryption with multimodal biometric authentication technique is proposed. In this method, the standard biometric templates are generated real-timely by the verification keys owned by legal user so that they are unnecessary to be stored in a database. Compared with the traditional recognition algorithms, storage space and matching time are greatly saved. In addition, the verification keys are difficult to be forged due to the utilization of optical encryption technique. Although the verification keys are lost or stolen, they are useless for others in absence of the legal owner's biometric. A series of numerical simulations are performed to demonstrate the feasibility and performance of this method.

  16. Multimodal imaging of vascular network and blood microcirculation by optical diagnostic techniques

    SciTech Connect

    Kuznetsov, Yu L; Kalchenko, V V; Meglinski, I V

    2011-04-30

    We present a multimodal optical diagnostic approach for simultaneous non-invasive in vivo imaging of blood and lymphatic microvessels, utilising a combined use of fluorescence intravital microscopy and a method of dynamic light scattering. This approach makes it possible to renounce the use of fluorescent markers for visualisation of blood vessels and, therefore, significantly (tenfold) reduce the toxicity of the technique and minimise side effects caused by the use of contrast fluorescent markers. We demonstrate that along with the ability to obtain images of lymph and blood microvessels with a high spatial resolution, current multimodal approach allows one to observe in real time permeability of blood vessels. This technique appears to be promising in physiology studies of blood vessels, and especially in the study of peripheral cardiovascular system in vivo. (optical technologies in biophysics and medicine)

  17. A novel noninvasive all optical technique to monitor physiology of an exercising muscle

    NASA Astrophysics Data System (ADS)

    Saxena, Vishal; Marcu, Laura; Karunasiri, Gamani

    2008-11-01

    An all optical technique based on near-infrared spectroscopy and mid-infrared imaging (MIRI) is applied as a noninvasive, in vivo tool to monitor the vascular status of skeletal muscle and the physiological changes that occur during exercise. A near-infrared spectroscopy (NIRS) technique, namely, steady state diffuse optical spectroscopy (SSDOS) along with MIRI is applied for monitoring the changes in the values of tissue oxygenation and thermometry of an exercising muscle. The NIRS measurements are performed at five discrete wavelengths in a spectral window of 650-850 nm and MIRI is performed in a spectral window of 8-12 µm. The understanding of tissue oxygenation status and the behavior of the physiological parameters derived from thermometry may provide a useful insight into muscle physiology, therapeutic response and treatment.

  18. Optical sensing of peroxide using ceria nanoparticles via fluorescence quenching technique

    NASA Astrophysics Data System (ADS)

    Shehata, N.; Samir, E.; Gaballah, S.

    2016-04-01

    This study introduces the application of small ceria nanoparticles (NPs) as optical sensor for peroxide using fluorescence quenching technique. Our synthesized ceria nanoparticles have the ability to adsorb peroxides via its oxygen vacancies. Ceria nanoparticles (NPs) solution with added variable concentrations of hydrogen peroxides is exposed through near UV excitation and the detected visible fluorescent emission is found to be at 520nm, with reduced peak intensity peaks with increasing the peroxide concentrations due to static fluorescence quenching technique. The relative intensity change of the visible fluorescent emission has been reduced to more than 50% at added peroxide concentrations up to 10 wt.%. This research work could be applied further in optical sensors of radicals in biomedical engineering and environmental monitoring.

  19. Optical sensing of peroxide using ceria nanoparticles via fluorescence quenching technique

    NASA Astrophysics Data System (ADS)

    Shehata, Nader; Samir, Effat; Gaballah, Soha; Salah, Mohammed

    2016-07-01

    This study introduces the application of ceria nanoparticles (NPs) as an optical sensor for peroxide using fluorescence quenching technique. Our synthesized ceria NPs have the ability to adsorb peroxides via its oxygen vacancies. Ceria NPs solution with added variable concentrations of hydrogen peroxides is exposed through near-UV excitation and the detected visible fluorescent emission is found to be at ˜520 nm. The fluorescent intensity peak is found to be reduced with increasing the peroxide concentrations due to static fluorescence quenching technique. The relative intensity change of the visible fluorescent emission has been reduced to more than 50% at added peroxide concentrations up to 10 wt. %. In order to increase ceria peroxides sensing sensitivity, lanthanide elements such as samarium (Sm) are used as ceria NPs dopant. This research work could be applied further in optical sensors of radicals in biomedical engineering and environmental monitoring.

  20. Optical Fourier techniques for medical image processing and phase contrast imaging

    PubMed Central

    Yelleswarapu, Chandra S.; Kothapalli, Sri-Rajasekhar; Rao, D.V.G.L.N.

    2008-01-01

    This paper briefly reviews the basics of optical Fourier techniques (OFT) and applications for medical image processing as well as phase contrast imaging of live biological specimens. Enhancement of microcalcifications in a mammogram for early diagnosis of breast cancer is the main focus. Various spatial filtering techniques such as conventional 4f filtering using a spatial mask, photoinduced polarization rotation in photosensitive materials, Fourier holography, and nonlinear transmission characteristics of optical materials are discussed for processing mammograms. We also reviewed how the intensity dependent refractive index can be exploited as a phase filter for phase contrast imaging with a coherent source. This novel approach represents a significant advance in phase contrast microscopy. PMID:18458764